Rozprawy doktorskie na temat „Steel alloys – Corrosion”
Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Steel alloys – Corrosion.
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Steel alloys – Corrosion”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
1
Harty, Brian Dudley. "Corrosion fatigue of engineering alloys in aqueous environments". Doctoral thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/18215.
Pełny tekst źródłaStreszczenie:
A comparative study of the fatigue crack growth rate (FCGR) behaviour of five alloys in air and in aqueous environments has been performed. The alloys tested include: mild steel as a reference material, a corrosion resistant dual phase steel, 3CR12, a proprietary martensitic stainless steel, AISI 431, a newly developed 8% Cr martensitic steel, Alloy 825, and a newly developed corrosion-abrasion resistant metastable austenitic alloy, 1210. Tests were conducted in laboratory air, distilled water at rest potential, 500 ppm chloride solution at rest potential, 1000 ppm chloride solution at rest potential, and 1000 ppm chloride solution at -1200 m V see; solution temperatures were maintained at 25⁰ C. Crack growth rate tests were performed using sinusoidal loading at a load ratio R = 0.1, a frequency of 3Hz in the laboratory air, and a frequency of 1 Hz in the aqueous environments. At the completion of testing, fracture surfaces were studied using a scanning electron microscope. In air, the mild steel and 3CR12 display comparable rates of cracking and exhibit a greater resistance to fatigue crack propagation than the martensitic AISI 431 and Alloy 825; Alloy 825 shows the least resistance to fatigue crack propagation. The deformation induced transformation in 1210 gives this alloy the greatest resistance to fatigue crack propagation in air. Fatigue crack growth rates were all enhanced in the aqueous environments. The greatest overall rate of environmentally assisted cracking was shown by alloy 825 while the lowest was shown by the mild steel. Although the rate of cracking of 1210 in the aqueous environments was less than that of Alloy 825, 1210 was influenced the most by the aqueous environments. An environmentally assisted cracking index shows that the rate of fatigue crack propagation in 1210 is increased by 32 times in the 500 ppm chloride solution at low stress intensities. The fatigue crack growth rates of mild steel and AISI 431 were significantly influenced by the cathodically polarised conditions in the 1000 ppm chloride solution, compared to the rest potential conditions. In these cases hydrogen was seen to be evolved from the specimen surfaces. Changes in the fatigue crack growth rate behaviour were accompanied by changes in the fracture surface morphologies. The observed changes varied for each alloy and for each environment, and were manifest by the degree of intergranular cracking, cleavage, quasi cleavage, and increased coarseness of the transgranular cracking. The fracture surface morphologies are reported and discussed in detail. In general, the fracture surface morphologies could be directly related to the relative degrees of environmental influence on the rate of cracking; results are explained in terms of existing hypotheses. It is suggested that the environmentally assisted cracking of mild steel and AISI 431 at cathodic potentials in the 1000 ppm chloride solution could only be attributed to hydrogen assisted cracking. Similarly, it is suggested that the large crack growth rate acceleration of 1210 in the aqueous environments could also be attributed to hydrogen. The similar fracture surface morphologies observed on the other specimens after tests in the aqueous environments suggests-that hydrogen could be responsible for the environmentally assisted cracking of all the steels in aqueous environments.
2
Morrissey, Francis H. J. "A study of fracture and segregation in corrosion resistant alloys : 316ss, Alloy 600 and Alloy 690". Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284840.
Pełny tekst źródła
3
Kim, Yeong Ho. "Chromium-free consumable for welding stainless steel corrosion perspective /". Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1133285376.
Pełny tekst źródła
4
Kear, Gareth. "Electrochemical corrosion of marine alloys under flowing conditions". Thesis, University of Portsmouth, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369433.
Pełny tekst źródła
5
Kish, Joseph J. "Active-passive corrosion of Fe-Cr-Ni alloys in hot concentrated sulphuric acid solutions /". *McMaster only, 1999.
Znajdź pełny tekst źródła
6
Armstrong, Derek C. "Influence of segregated impurities on the corrosion and oxidation of ferrous alloys". Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239600.
Pełny tekst źródła
7
Sneddon, A. D. "Macrofouling and corrosion of steels and copper-nickel alloys in seawater". Thesis, Robert Gordon University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378071.
Pełny tekst źródła
8
Cotterrell, M. H. "The influence of water composition on the pitting behaviour of newly developed corrosion resistant steels". Master's thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/21134.
Pełny tekst źródłaStreszczenie:
Bibliography: pages 96-103.The mechanisation of the working stapes in South African gold mines has required the introduction of a fundamentally new technology, hydro-power, in which machines are powered hydraulically using mine water fed from above ground. Mine water is aggressive and has a variable acidity and pH, and contains high concentrations of sulphate, chloride and nitrate ions. In order to minimise the pitting corrosion of piping and stoping machinery a compromise between selecting a suitable corrosion resistant material and treating the mine water to an acceptable level of corrosiveness is being sought.
9
Yin, Maggie Huaying Materials Science & Engineering Faculty of Science UNSW. "Metal dusting of iron and low alloy steel". Awarded by:University of New South Wales. School of Materials Science and Engineering, 2006. http://handle.unsw.edu.au/1959.4/25188.
Pełny tekst źródłaStreszczenie:
Metal dusting is a kind of catastrophic corrosion phenomenon that can be observed in several of petrochemical processes. It occurs on iron-, nickel- and cobalt-base metals in carbonaceous atmospheres at high temperature when gaseous carbon activity is higher than one. The process is particularly rapid for ferritic alloys The aim of this project was to compare the dusting kinetics of pure iron and a 2.25Cr-1Mo alloy steel under CO-H2-H2O atmosphere at 650??C. Polished (3??m) samples of iron and the steel were exposed to flowing CO-H2-H2O gas atmospheres at 650??C, when the gases were supersaturated with respect to graphite. The partial pressure of CO was varied between 0.25 and 0.9 atm, and the carbon activity was varied from 2.35 to 16, in order to obtain a series of experimental conditions. In most experiments, pO2 was less than 7.37E-24 atm, and no iron oxide could form. However, Cr2O3 would always have been stable. When exposed to these gases, both iron and steel developed a surface scale of Fe3C which was buried beneath a deposit of carbon, containing iron-rich nanoparticles (the dust). Examination by Scanning Electron Microscopy allowed the observation of fine and coarse carbon nanotubes, and also spiral filaments. However, the morphology of the graphitic carbon was not sensitive to pCO and aC. Moreover, the carbon deposit was gas permeable, allowing continuing gas access to the underlying metal. At a fixed=4.5, the carburizing rate clearly increased with CO content from 0.25 to 0.68 atm. However, increasing the CO content to higher value led to decreased rates, indicating that carburizing rate reaches a maximum value at pCO=0.68 atm. When pCO was fixed at 0.25 atm and 0.68 atm, and carbon activity was varied. The induction period was extended by the formation of protective oxide layers at low values of carbon activity (aC= 2.35 and 2.55) where pO2 exceed the iron oxide formation value. For other reaction conditions, the carbon uptake rate for iron and steel did not increase with aC. The present work showed that the carbon deposition rates were not proportional to pCO or pCOpH2. Instead, the rate was affected by the partial pressure of all three reaction gases, and the carbon uptake rate for both materials could be expressed at r=k1pCOpH2+k2pCO2+k3pH22 and the rate constant k3 has a negative value, corresponding to coke gasification. From XRD analyses, it was found that cementite was the only iron-containing phase in the dusting product. The cementite particles acted as catalysts for carbon deposition from the gas. The same deposition process at the surface of the cementite layer led to its disintegration, thereby producing the particles. This disintegration process was faster on the steel than on pure iron. Consequently, the rates of both metal wastage and coke accumulation were faster for the steel. It is concluded that chromium and molybdenum do not stabilize the carbide but accelerate its disintegration process. It is suggested that Cr2O3 fine particles in the cementite layers provide more nucleation sites in the cementite layer on steel, explaining its more rapid dusting kinetics. However, appropriate methods of proving this assumption, such as TEM and FIB, are required.
10
Mohorich, Michael E. "Electrochemical corrosion behavior of AISI 4340 steel in multi-ionic solutions". abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1459436.
Pełny tekst źródła
11
Hays, Richard A. "Surface residual stress effects on stress corrosion cracking/hydrogen embrittlement behavior of AISI 4340 steel". Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/80148.
Pełny tekst źródłaStreszczenie:
A series of experiments was performed in an attempt to measure the effects of surface residual stresses on the stress corrosion cracking/hydrogen embrittlement (SCC/HE) behavior of AISI 4340 steel. Stress corrosion tests were performed under load control on cylindrical and notched tensile specimens in acidified 3.5% NaCl solution. The electrochemical potential of the specimens was maintained at -0.7 V versus a saturated calomel reference electrode. Time to failure for specimens tested at various applied and residual stress levels was measured. Stress relieved specimens as well as specimens containing mechanically induced residual stresses were tested. Residual stresses were estimated using Neuber's rule and were measured using an x-ray diffraction technique. In all cases, the sum of the applied and residual stresses was greater than zero.
Test results showed the initiation of SCC/HE cracks to be insensitive to the effects of surface residual stresses under the conditions evaluated. This is probably a result of the total time to failure criterion used to evaluate the SCC/HE tests. The extremely aggressive environment used in these experiments apparently led to rapid crack initiation, even in specimens containing compressive residual stresses. Another possible explanation of the insensitivity of this series of tests is crack initiation in the interior of the specimens below the depth of the mechanically induced residual stresses.Master of Science
12
Saire, Yanez Julio J. "Morphology and Detection of Corrosion on Stainless Steel Reinforcement in Concrete". Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7922.
Pełny tekst źródłaStreszczenie:
Stainless steel (SS) has emerged as an alternative corrosion-resistant reinforcement in concrete instead of the commonly used carbon steel (CS). The biggest advantage of SS is that it takes more time for corrosion to initiate than for CS. An additional benefit from the use of SS in concrete may be derived from the period after the corrosion started until the concrete structure reaches a limit state. This period is called corrosion propagation stage (CPS) and it has been hardly studied in SS reinforced structures. The duration of this period could be related, among other factors, to the morphology of corrosion of stainless steel in concrete. In some instances, the corrosion detection methods for CS have been used on SS reinforced structures to estimate the corrosion condition. However, there is uncertainty if these methods can detect corrosion in SS reinforced structures properly. This investigation was organized in two parts: literature review and experimental work.
The literature review indicated among other findings that the duration of the CPS of SS’s embedded in concrete may be estimated to be in the order of several decades. High-grade SS’s would have a longer duration of the CPS. The review also indicated that even localized corrosion of SS reinforcement may induce concrete cracking. The literature also suggested that the corrosion detection on SS reinforced concrete may require a combination of conventional methods (half-cell potential) and advanced electrochemical techniques such as Electrochemical Impedance Spectroscopy, Electrochemical noise, etc.
The experimental work focused on further determining whether corrosion of SS in concrete can be detected by methods traditionally used for CS reinforcement, and to what extent localization of corrosion of SS compares with that of CS in concrete. The experiments consisted in accelerated corrosion testing of controlled anodic regions along concrete beams, for which tests were designed and initiated.
Martensitic UNS S41000 SS bars were partially embedded in chloride contaminated concrete (5.84% by weight of cement) to cause active corrosion. AISI 1018 CS was also used for comparison purposes. Traditional half-cell potential measurements on the reinforced concrete specimens were evaluated in comparison to that of advanced electrochemical impedance spectroscopy. Additional concrete resistivity monitoring gave an indication of the degree of the pore structure formation.
The traditional half-cell potential measurements on AISI 1018 CS reinforced concrete specimens appeared to be suitable to estimate the corrosion state of the reinforcement. However, there was uncertainty on the interpretation of the half-cell potential results and thus the corrosion state of UNS S41000 SS reinforced concrete specimens.
Low-dispersion corrosion rates values were found over large areas on SS and CS bars in concrete, but that SS embedded in concrete also seemed to develop instances of corrosion rate peaks. Among other findings, the duration of CPS of CS in concrete was estimated to be in the interval [6-59] years. Assuming that the CPS had been reached, SS specimens in concrete appeared to have a much longer duration of CPS than CS, with an interval [57-253] years. However, this assumption is likely not valid and more work is required to assess the CPS of SS reinforced concrete.
13
Athasniya, Mohit. "Extrinsic Influence of Environment on Tensile Response, Impact Toughness and Fracture Behavior of Four Metals: Ferrous Versus Non Ferrous". University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1444242002.
Pełny tekst źródła
14
Xu, Nan Materials Science & Engineering Faculty of Science UNSW. "Corrosion behaviour of aluminised steel and conventional alloys in simulated aluminium smelting cell environments". Awarded by:University of New South Wales. School of Materials Science & Engineering, 2002. http://handle.unsw.edu.au/1959.4/18760.
Pełny tekst źródłaStreszczenie:
Aluminium smelting is a high temperature electrometallurgical process, which suffers considerable inefficiencies in power utilization and equipment maintenance. Aluminium smelting cell works in the extreme environments that contain extraordinarily aggressive gases, such as HF, CO and SO2. Mild steel used as a structural material in the aluminium industry, can be catastrophically corroded or oxidized in these conditions. This project was mainly concerned with extending the lifetime of metal structures installed immediately above the aluminium smelting cells. An aluminium-rich coating was developed on low carbon steel A06 using pack cementation technique. Yttria (Y2O3) was also used to improve the corrosion resistance of coating. Kinetics of the coating formation were studied. XRD, FESEM and FIB were employed to investigate the phase constitution and the surface morphology. Together with other potentially competitive materials, aluminium-rich coating was evaluated in simulated plant environments. Results from the long time (up to 2500h) isothermal oxidation of materials at high temperature (800??C) in air showed that the oxidation resistance of coated A06 is close to that of stainless steel 304 and even better than SS304 in cyclic oxidation tests. Coated A06 was also found to have the best sulfidation resistance among the materials tested in the gas mixture contains SO2 at 800??C. Related kinetics and mechanisms were also studied. The superior corrosion resistance of the coated A06 is attributed to the slow growing alpha-Al2O3 formed. Low temperature corrosion tests were undertaken in the gas mixtures containing air, H2O, HCl and SO2 at 400??C. Together with SS304 and 253MA, coated A06 showed excellent corrosion resistance in all the conditions. The ranking of the top three materials for corrosion resistance is: 253MA, coated A06 and SS304. It is believed that aluminised A06 is an ideal and economical replacement material in the severe corrosive aluminium smelting cell environment.
15
Coimbatore, Dhandayuth Venkatesh. "Cerium chloride inhibition for high strength low alloy steel exposed to sulphide polluted seawater". University of Western Australia. School of Mechanical Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0134.
Pełny tekst źródłaStreszczenie:
[Truncated abstract] Corrosion of steel structures caused by sulphide is a common engineering problem encountered by many industries, such as the petroleum, chemical processing, mining and mineral processing industries. The control of sulphide corrosion is still a controversial topic among corrosion engineers. There is an absence of guideline for a reliable acceptable limit of sulphide level in service and each processing industry has its own empirical values. Selection of inhibitors in the sulphide environment depends on laboratory testing before its actual application in pipelines and reaction vessels. Many investigators have postulated the corrosion mechanisms due to sulphide based on operating envelopes such as pH, chloride, manganese, hydrogen sulphide, sulphate reducing bacteria levels and inhibitor concentration. It is recommended in the literature that the batch dosing of inhibitor and biocide needs to be evaluated in regards to sulphide reducing bacteria (SRB) level, which may produce sulphide concentrations up to 2000 ppm. Although sulphide scale formation may protect the base metal by providing a physical barrier, the detrimental effects of sulphide are often inevitable, such as stress corrosion cracking, hydrogen embrittlement, etc. Currently, there are many chemicals that are used as inhibitors to prevent corrosion by scavenging the sulphide from the environment. Cerium, a rare-earth element, is not used as inhibitor in the sulphide environment. Also, there are no previous research findings on the effects of compounds of rare-earth metals, such as cerium chloride (CeCl3), in sulphide environment. This research examines the corrosion behaviour of 0.4Mo-0.8Cr steel, a High Strength Low Alloy (HSLA) steel, in sulphide-polluted artificial seawater with the addition of CeCl3 and glutaraldehyde. ... It is postulated that the moderate inhibiting effect of CeCl3 is due to the scavenging effect thereby forming Ce2S3 complex. Further reaction of sulphide with steel resulted in ferrous sulphide, leading to an increased corrosion rate. It is also concluded that the CeCl3 interferes with both anodic and cathodic reactions in deaerated conditions. Addition of glutaraldehyde in the sulphide-polluted seawater was found to decrease the corrosion rate. According to the electrochemical measurements conducted, the concurrent addition of glutaraldehyde and CeCl3 appeared to have an added effect on reducing the corrosion of the steel, as evidenced by the increase of the open circuit potential during the short-term testing. From the weight loss measurements after 60 days, sulphide pollution in deaerated seawater was found to increase corrosion rate. This is attributed to the increase of sulphide activity whereby continual dissolution of steel was encountered. From the weight loss tests, it was found that the addition of CeCl3 and glutaraldehyde reduced the corrosion rate of the steel in the solutions containing 0-10 ppm sulphide. There is no noticeable corrosion rate decrease for the solution containing 100 ppm sulphide. The added effect of CeCl3 and glutaraldehyde to the SRB medium has resulted in lower corrosion rates. Further detailed experimentation is required to elucidate the corrosion reduction mechanism in glutaraldehyde-containing environments.
16
Jones, Franziska Anna. "The Effect of a High-Temperature High-Pressure Nitrogen Environment with Carbonaceous Impurities on the Performance of Three Austenitic Alloys". Thesis, University of Canterbury. Mechanical Engineering, 2007. http://hdl.handle.net/10092/3268.
Pełny tekst źródłaStreszczenie:
WhisperGenTM heater head components are currently machined from the austenitic stainless steel Sandvik 253MA. The inner surface of the heater heads is subjected to the working gas of the engine, which is a high-pressure, high-temperature nitrogen-based environment with carbonaceous impurities. As a result of this exposure, a scale forms during operation and eventually spalls. This spalled scale causes abrasive damage to piston seals and guides, which leads to pressure loss and eventual failure of the engine. The aim of the present work was to compare the performance of the austenitic alloy 253MA with two alternative alloys, Incoloy 800H and AISI 310, thereby enabling a material recommendation. A literature review provided information about many general aspects of high temperature corrosion in similar alloys. However, little was found about the application of these alloys in environments similar to those experienced by a WhisperGenTM heater head. Therefore, laboratory experiments were conducted to indicate the relative performance characteristics of the three potential alloys (253MA, Incoloy 800H and AISI 310). To overcome the difficulties with testing at high temperatures and pressures, Thermo-Calc™ was used to calculate gas mixtures at 1 bar that approximated the chemical potentials of carbon and nitrogen in the working gas at 24 bar. Comparisons of the different materials were made via weight loss/gain measurements and metallographic analysis, which included optical microscopy, scanning electron microscopy, X-ray mapping and electron back scatter diffraction (EBSD). The laboratory test sample results were also compared with results from heater heads of the same materials that were run in an actual WhisperGenTM engine. The experimental results taken in total indicate that 253MA is the least suitable alloy for the heater head application because it exhibited poor spalling performance, internal oxidation and formation of a large amount of Cr23C6. AISI 310 was shown in all cases to develop the detrimental sigma phase, although this alloy was the least susceptible to internal oxidation. Incoloy 800H was the most resistant alloy to all forms of degradation and is thus recommended for the heater head application.
17
Azzi, Marwan. "Role of synergy between wear and corrosion in degradation of materials". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115871.
Pełny tekst źródłaStreszczenie:
Tribocorrosion is a term used to describe the material degradation due to the combination of electrochemical and tribological processes. Due to a synergetic effect, the material loss can be larger than the sum of the losses due to wear and corrosion acting separately. In this thesis, the synergy of wear and corrosion was investigated for different types of material, namely the Ti-6Al-4V alloy, the SS316L stainless steel coated with a thin film of Diamond Like Carbon (DLC), and the SS301 stainless steel coated with a thin film of chromium silicon nitride (CrSiN).A tribocorrosion apparatus was designed and constructed to conduct wear experiments in corrosive media. Sliding ball-on-plate configuration was used in this design, where the contact between the ball and the specimen is totally immersed in the test electrolyte. The specimen was connected to a potentiostat to control its electrochemical parameters, namely the potential and the current. Electrochemical techniques were used to control the kinetics of corrosion reactions, and therefore it was possible to assess separately the role of corrosion and wear in the total degradation of material, and to evaluate the synergy between them.
For Ti-6Al-4V, it was found that the corrosion and tribocorrosion depend strongly on the structure of the material. The alpha-equiaxed microstructure with fine dispersed beta-phase exhibited the best corrosion resistance. The corrosion resistance was found to decrease when the basal plane was preferentially aligned parallel to the surface, which is attributed to a low resistance to charge transfer in the oxide films formed on this plane. On the other hand, when wear and corrosion were involved simultaneously, the oxide layer protecting the substrate against dissolution was mechanically destroyed leading to a high corrosion rate. It was found that the hardness was the most important factor determining the tribocorrosion behavior of the Ti-6Al-4V alloy; samples with high hardness exhibited less mechanical wear, less wear-enhanced corrosion, and less corrosion-enhanced wear.
For DLC coatings, it was found that interface engineering plays a crucial role in the tribocorrosion behavior of DLC films. DLC films with nitrided interface layer (SS\N3h\DLC) were shown to have very poor tribocorrosion resistance; the DLC film delaminated from the substrate after 50 cycles of sliding wear at 9 N load in Ringer's solution. It should be mentioned that a previous study performed at Ecole Polytechnique de Montreal [4] has shown that the same coating resisted 1800 cycles of dry wear at 22 N without delamination. This demonstrates clearly the effect of corrosion on the wear resistance of DLC films. The use of a-SiN:H bond layer between the SS316L substrate and the DLC film improved significantly the tribocorrosion behavior of the coating. This layer acts as a barrier against corrosion reaction; the polarization resistance was 5.76 GO.cm2 compared to 27.5 MO.cm2 and 1.81 MO.cm2 for the DLC-coated SS316L with nitrided interface layer and the bare substrate, respectively.
For CrSiN coatings, it was also shown that nitriding treatment of the substrate prior to deposition reduces significantly the tribocorosion resistance of the CrSiN-coated SS301 substrates. This is attributed to the peculiar morphology of the nitrided surface prior to deposition. The high relives at the grain boundaries of the substrate may be the reason for the generation, during sliding wear, of defects in the film, which makes the infiltration of the liquid easier, and consequently leads to the destruction of the CrSiN film.
18
Evin, Harold. "Low Cr alloys with an improved high temperature corrosion resistance". Thesis, Dijon, 2010. http://www.theses.fr/2010DIJOS082/document.
Pełny tekst źródłaStreszczenie:
Les aciers ferritiques à faible teneur en chrome tel que le T/P91 sont largement utilisés dans les centrales de productions d’électricité pour leurs bonnes propriétés mécaniques et leur faible coefficient d’expansion thermique. Cependant, la demande croissante en énergie alliée à la nécessité de réduire les émissions de gaz à effet de serre, conduisent à envisager l’augmentation des conditions d’utilisation (température et pression) de ces matériaux. Des études ont montré qu’en modifiant la température de fonctionnement et la pression de vapeur d’eau de 538°C/18.5 MPa à 650°C/30 MPa, le rendement des centrales thermiques progressait d’environ 8%. Se pose alors la question de la tenue à la corrosion à haute température des aciers à 9% de chrome. Au cours de ces travaux, le comportement d’un acier ferritique/ martensitique à 9% de chrome a été étudié à 650°C sous air sec et sous vapeur d’eau de matière isotherme et en conditions de cyclage thermique. La prise de masse des échantillons renseigne sur la cinétique de la réaction d’oxydation et l’adhérence des couches d’oxydes formées. Les produits de corrosion ont été caractérisés par plusieurs techniques d’analyses dans l’optique de clairement identifiés les oxydes en présences et leurs mécanismes de formation. Des oxydes mixtes de fer et de chrome (Cr,Fe)2O3 sont dans un premier temps formés et assurent s’avèrent être temporairement protecteur. Pour des longs temps d’oxydation ou des températures supérieures à 650°C, la magnétite Fe3O4 et l’hématite Fe2O3 sont les principaux oxydes formés, montrant ainsi l’inadéquation des nuances à faible teneur en chrome pour une utilisation dans des conditions aussi drastiques. Dans l’optique d’augmenter la résistance à la corrosion à haute température de cet alliage, diverses solutions ont été envisagées tel que l’aluminisation par cémentation en caisse, les revêtements d’oxydes de terre rare par MOCVD, ou encore l’ajout d’éléments d’addition. Ces solutions ont été également testées à 650°C sous air sec et sous vapeur d’eauThe improvement of high temperature oxidation resistance of low chromium content steels, such as T/P91, is of great interest in regards with their application in thermal power generating plants. Indeed, they possess good creep properties, and low thermal expansion coefficient. Important needs in energy together with environmental issues place power generation plants under constraints which lead to develop high efficiency systems. A usual way to increase the efficiency consists in increasing temperature and pressure parameters of the power generating plant. Studies has shown that the total efficiency of a plant increases by nearly 8 % when changing the steam parameters from 538°C/18.5 MPa to 650°C/30 MPa. Then, the problem of corrosion resistance of 9% chromium steel in those conditions is asked. In this work, the behavior of a ferritic / martensitic 9% chromium steel has been studied at 650°C in dry air and in water vapor containing environment in both isothermal and thermal cyclic conditions. The weight gain of samples provides information on the kinetics of the oxidation reaction and the adhesion of formed oxide scale. Corrosion products were characterized by several analytical techniques in order to identify oxides with accuracy and to understand their formation mechanisms. Mixed iron and chromium oxides (Cr, Fe) 2O3 are initially formed and provide temporary protection to the substrate. For long time exposure or temperatures above 650°C, magnetite, Fe3O4 and hematite Fe2O3 are the main oxides formed, highlighting the fact that low chromium steel are inappropriate for applications in such drastic conditions. In order to increase the high temperature corrosion resistance of this alloy, various solutions have been proposed as aluminizing by pack cementation, reactive element oxides coatings of by MOCVD, or addition of alloying elements in the steel composition. These solutions were then tested at 650 ° C in dry air and in water vapor environments
19
Wang, Xiaolan. "The effects of rust on the gas carburization of AISI 8620 steel". Worcester, Mass. : Worcester Polytechnic Institute, 2008. http://www.wpi.edu/Pubs/ETD/Available/etd-073108-094449/.
Pełny tekst źródła
20
Zawai, Khaled Al. "Understanding the role of erosion/corrosion interactions in degredation of steel and stainless steel alloys in systems containing sand and oil". Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.550334.
Pełny tekst źródłaStreszczenie:
Erosion and corrosion of piping and 'equlpments continues to be a problem for the oil and gas sector. This primarily occurs where water and entrained sand are present in produced water. The pipelines used to transport these products are often subjected to multiphase flow regimes, which can result in severe degradation of the internal surfaces with the presence of solid particles and an oil phase in the flow system, and the erosion-corrosion mechanisms become more complicated when compared with those seen in single-phase systems. Therefore, it is essential to understand the degradation mechanisms involved to enable effective material selection to be achieved. In this project, a study on sand mobility was conducted, which focused on the effect of the corrosion inhibitor and oil phase adsorption on the sand particles and the effect of the mobility of sand particles in a flow system. A flow loop coupled with a high-speed camera was designed to enable the sand transport to be visualised. With such a system, the consequence of the corrosion inhibitor and hydrocarbon phase, ISOPAR M, on the adsorption process of the sand particles, and the effect of adsorption on reducing the kinetic energy of sand particles were studied. Zeta potential, which is a function of the mobility of an electrical charge at the slip plane beyond which the electrical charges form a stable entity with the solid particle, was also introduced in this work to confirm the result of the sand transport and to define the condition at which adsorption is possible. The results of zeta potential were in good agreement with the results of the sand mobility obtained by the designed flow loop and adjusted jet impingement rig. The results showed that the adsorption of corrosion inhibitor on the surface of sand particles is only possible if the corrosion inhibitor acquires an opposite charge to the sand particles dispersed in solution (the attraction force is dominant). In the study, the erosion-corrosion of a carbon steel (API-5L-X65), 13Cr martensitic stainless steel and duplex/superduplex stainless steel (22Cr and 25Cr) were assessed by jet impingement using a combination of electrochemical tests and metal loss analysis. The assessments were conducted under a simulated CO2 erosive-corrosive oil and gas surface pipeline with the presence of hydrocarbon and corrosion inhibitor to understand the material degradation mechanisms under different testing media to enable supportive information to be provided for the mitigation of erosion-corrosion in the oil and gas industry. In-situ electrochemistry, LPR, was conducted in order to assess the contribution of the corrosion process on the total degradation of materials. Despite the significant effect of the solution containing 5 vol% ISOPAR M on the total weight loss (TWL), the addition of 5% ISOPAR M did not show a clear reduction in the corrosion rate (higher slope of I'1E/l'1i plot). It was proved in this project that the presence of 5 vol% ISOPAR M not only has an important role in reducing the impact velocity of sand particles, but using CFD simulation it was also proved that the particles had a lower impact angle, and, hence, reduced the overall damage to the mechanical component (erosion-corrosion). The other interesting feature identified in this study is the interaction between the corrosion inhibitor and oil phase, which resulted in enhancing the stability of the emulsion flow and the change in the wettability of the metal surface. Unlike other testing media, the measured contact angles of water droplets on API-5L-X65 surfaces, pre-exposed to the solution containing 100 ppm of corrosion inhibitor and 5 vol% hydrocarbon, led some sites on the surface to change to an oil wet, hydrophobic surface, thereby increasing the corrosion resistance. A three-level experimental design with full replication was developed for the purpose of developing a statistical model (using the commercial package Minitab™) relating to the total weight loss of API-5L-X65. Such a model will enhance the understanding of the performance of a material in a multiphase flow environment. This methodology allows the interaction between the most significant parameters on erosion corrosion to be studied. Finally, this thesis has added to the understanding of erosion-corrosion in conditions containing a hydrocarbon phase and sand particles.
21
Olander, Andrew F. "Effects of passivation treatments on corrosion behavior and passive film composition for 316L stainless steel and alloy MP 35N". Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/19912.
Pełny tekst źródła
22
Barke, Derek Woolrich 1975. "An in situ test for stress corrosion damage and tension in bolts". Monash University, Dept. of Mechanical Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/7686.
Pełny tekst źródła
23
Zhang, Xian. "Atmospheric corrosion of zinc-aluminum and copper-based alloys in chloride-rich environments : Microstructure, corrosion initiation, patina evolution and metal release". Doctoral thesis, KTH, Yt- och korrosionsvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-151180.
Pełny tekst źródłaStreszczenie:
Fundamental understanding of atmospheric corrosion mechanisms requires an in-depth understanding on the dynamic interaction between corrosive constituents and metal/alloy surfaces. This doctoral study comprises field and laboratory investigations that assess atmospheric corrosion and metal release processes for two different groups of alloys exposed in chloride-rich environments. These groups comprise two commercial Zn-Al alloy coatings on steel, Galfan™ (Zn5Al) and Galvalume™ (Zn55Al), and four copper-based alloys (Cu4Sn, Cu15Zn, Cu40Zn and Cu5Zn5Al). In-depth laboratory investigations were conducted to assess the role of chloride deposition and alloy microstructure on the initial corrosion mechanisms and subsequent corrosion product formation. Comparisons were made with long-term field exposures at unsheltered marine conditions in Brest, France. A multitude of surface sensitive and non-destructive analytical methods were adopted for detailed in-situ and ex-situ analysis to assess corrosion product evolution scenarios for the Zn-Al and the Cu-based alloys. Scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS) were employed for morphological investigations and scanning Kelvin probe force microscopy (SKPFM) for nobility distribution measurements and to gain microstructural information. SEM/EDS, infrared reflection-absorption spectroscopy (IRAS), confocal Raman micro-spectroscopy (CRM) and grazing incidence x-ray diffraction (GIXRD) were utilized to gain information on corrosion product formation and possibly their lateral distribution upon field and laboratory exposures. The multi-analytical approach enabled the exploration of the interplay between the microstructure and corrosion initiation and corrosion product evolution. A clear influence of the microstructure on the initial corrosion product formation was preferentially observed in the zinc-rich phase for both the Zn-Al and the Cu-Zn alloys, processes being triggered by microgalvanic effects. Similar corrosion products were identified upon laboratory exposures with chlorides for both the Zn-Al and the Cu-based alloys as observed after short and long term marine exposures at field conditions. For the Zn-Al alloys the sequence includes the initial formation of ZnO, ZnAl2O4 and/or Al2O3 and subsequent formation of Zn6Al2(OH)16CO3·4H2O, and Zn2Al(OH)6Cl·2H2O and/or Zn5(OH)8Cl2·H2O. The patina of Cu sheet consists of two main layers with Cu2O predominating in the inner layer and Cu2(OH)3Cl in the outer layer, and with a discontinuous presence of CuCl in-between. Additional patina constituents of the Cu-based alloys include SnO2, Zn5(OH)6(CO3)2, Zn6Al2(OH)16CO3·4H2O and Al2O3. General scenarios for the evolution of corrosion products are proposed as well as a corrosion product flaking mechanism for some of the Cu-based alloys upon exposure in chloride-rich atmospheres. The tendency for corrosion product flaking was considerably more pronounced on Cu sheet and Cu4Sn compared with Cu15Zn and Cu5Al5Zn. This difference is explained by the initial formation of zinc- and zinc-aluminum hydroxycarbonates Zn5(OH)6(CO3)2 and Zn6Al2(OH)16CO3·4H2O on Cu15Zn and Cu5Al5Zn, corrosion products that delay the formation of CuCl, a precursor of Cu2(OH)3Cl. As a result, the observed volume expansion during transformation of CuCl to Cu2(OH)3Cl, and the concomitant flaking process of corrosion products, was less severe on Cu15Zn and Cu5Al5Zn compared with Cu and Cu4Sn in chloride-rich environments. The results confirm the barrier effect of poorly soluble zinc and zinc-aluminum hydroxycarbonates Zn5(OH)6(CO3)2 and Zn6Al2(OH)16CO3·4H2O, which results in a reduced interaction between chlorides and surfaces of Cu-based alloys, and thereby reduced formation rates of easily flaked off corrosion products. From this process also follows reduced metal release rates from the Zn-Al alloys.Bättre molekylär förståelse för metallers atmosfäriska korrosion kräver en fördjupad kunskap i det dynamiska samspelet mellan atmosfärens korrosiva beståndsdelar och metallytan. Denna doktorsavhandling omfattar laboratorie- och fältundersökningar av korrosions- och metallfrigöringsprocesser av två grupper av legeringar som exponerats i kloridrika atmosfärsmiljöer: två kommersiella Zn-Al beläggningar på stål, Galfan™ (Zn med 5% Al, förkortat Zn5Al) och Galvalume™ (Zn55Al), samt fyra kopparbaserade legeringar (Cu4Sn, Cu15Zn, Cu40Zn och Cu5Zn5Al). Undersökningar har genomförts i renodlade laboratorie-miljöer med för-deponerade NaCl-partiklar i en atmosfär av varierande relativ fuktighet. Syftet har varit att utvärdera betydelsen av kloriders deposition och legeringarnas mikrostruktur på korrosionsmekanismen samt bildandet av korrosionsprodukter. Jämförelser av korrosionsmekanismer har även gjorts efter flerårsexponeringar av samma legeringar i en marin fältmiljö i Brest, Frankrike. Undersökningarna har baserats på ett brett spektrum av analysmetoder för detaljerade studier dels under pågående atmosfärisk korrosion (in-situ), och dels efter avslutad korrosion (ex-situ). Legeringarnas mikrostruktur och tillhörande variation i ädelhet hos olika faser har undersökts med svepelektronmikroskopi och energidispersiv röntgenmikroanalys (SEM/EDS) samt med en variant av atomkraftsmikroskopi (engelska: scanning Kelvin probe force microscopy, SKPFM). Korrosionsprodukternas tillväxt har analyserats in-situ med infraröd reflektions-absorptionsspektroskopi (IRAS), samt morfologi och sammansättning av bildade korrosionsprodukter ex-situ med SEM/EDS, konfokal Raman mikro-spektroskopi (CRM) samt röntgendiffraktion vid strykande ifall (GIXRD). Det multi-analytiska tillvägagångssättet har medfört att det komplexa samspelet mellan de skilda legeringarnas mikrostruktur, korrosionsinitiering och bildandet av korrosionsprodukter kunnat studeras i detalj. En tydlig påverkan av mikrostruktur på det initiala korrosionsförloppet har kunnat påvisas. Korrosionsinitieringen sker företrädesvis i mer zinkrika faser för såväl Zn-Al- som Cu-Zn-legeringar och orsakas av mikro-galvaniska effekter mellan de mer zinkrika, mindre ädla, faserna och omgivande faser. Deponerade NaCl-partiklar påskyndar den lokala korrosionen oberoende av mikrostruktur. Snarlika sekvenser av korrosionsprodukter har kunnat påvisas såväl efter laboratorie- som fältexponeringar. För Zn-Al-legeringar bildas först ZnO, ZnAl2O4 och/eller Al2O3, därefter Zn6Al2(OH)16CO3·4H2O och Zn2Al(OH)6Cl·2H2O och/eller Zn5(OH)8Cl2·H2O. På ren koppar bildas ett inre skikt dominerat av Cu2O, ett mellanskikt av CuCl och ett yttre skikt med i huvudsak Cu2(OH)3Cl. Beroende på legeringstillsats har även SnO2 och Zn5(OH)6(CO3)2 kunnat identifieras. En mekanism för flagning av korrosionsprodukter på kopparbaserade legeringar i kloridrika atmosfärer har utvecklats. Tendensen för flagning har visat sig vara mycket mer uttalad på ren Cu och Cu4Sn än på Cu15Zn och Cu5Al5Zn. Skillnaden kan förklaras med hjälp av det tidiga bildandet av Zn5(OH)6(CO3)2 och Zn6Al2(OH)16CO3·4H2O på Cu15Zn och Cu5Al5Zn som fördröjer bildandet av CuCl, en föregångare till Cu2(OH)3Cl. Därigenom hämmas även den observerade volymexpansionen som sker när CuCl omvandlas till Cu2(OH)3Cl, en process som visar sig vara den egentliga orsaken till att korrosionsprodukterna flagar. Resultaten bekräftar barriäreffekten hos de mer svårlösliga faserna Zn5(OH)6(CO3)2 och Zn6Al2(OH)16CO3·4H2O, vilken dels resulterar i en minskad växelverkan mellan klorider och de legeringsytor där dessa faser kan bildas, och dels i en reducerad metallfrigöringshastighet.
QC 20140915
Autocorr, RFSR-CT-2009-00015 Corrosion of heterogeneous metal-metal assemblies in the automotive industry
Atmospheric corrosion and environmental metal dispersion from outdoor construction materials
24
Moser, Robert David. "High-strength stainless steels for corrosion mitigation in prestressed concrete: development and evaluation". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41083.
Pełny tekst źródłaStreszczenie:
The use of stainless steel alloys in reinforced concrete structures has shown great success in mitigating corrosion in even the most severe of exposures. However, the use of high-strength stainless steels (HSSSs) for corrosion mitigation in prestressed concrete (PSC) structures has received limited attention. To address these deficiencies in knowledge, an experimental study was conducted to investigate the feasibility of using HSSSs for corrosion mitigation in PSC. The study examined mechanical behavior, corrosion resistance, and techniques for the production of HSSS prestressing strands. Stainless steel grades 304, 316, 2101, 2205, 2304, and 17-7 along with a 1080 prestressing steel control were included in the study. Tensile strengths of 1250 to 1550 MPa (181 to 225 ksi) were achieved in the cold-drawn HSSSs. 1000 hr stress relaxation of all candidate HSSSs was predicted to be between 6 and 8 % based on the results of 200 hr tests conducted at 70 % of the ultimate tensile strength. Residual stresses due to the cold drawing had a significant influence on stress vs. strain behavior and stress relaxation. Electrochemical corrosion testing found that in solutions simulating alkaline concrete, all HSSSs showed exceptional corrosion resistance at chloride (Cl-) concentrations from zero to 0.25 M. However, when exposed to solutions simulating carbonated concrete, corrosion resistance was reduced and the only HSSSs with acceptable corrosion resistance were duplex grades 2205 and 2304, with 2205 resistant to corrosion initiation at Cl- concentrations up to 1.0 M (twice that in seawater). Based on these results, duplex grades 2205 and 2304 were identified as optimal HSSSs and were included in additional studies which found that: (1) 2304 is susceptible to corrosion when tested in a stranded geometry, (2) 2205 and 2304 are not susceptible to stress corrosion cracking, and (3) 2205 and 2304 are susceptible to hydrogen embrittlement. Efforts focused on the production of 2205 and 2304 prestressing strands showed that they could be produced as strands using existing ASTM A416 prestressing strand production facilities. Due to the ferromagnetic properties of 2205 and 2304, a low-relaxation heat treatment was found to be a viable option to reduce stress relaxation and improve mechanical properties. The overall conclusion of the study was that HSSSs, especially duplex grades 2205 and 2304, show excellent promise to mitigate corrosion if utilized as prestressing reinforcement in PSC structures exposed to severe marine environments.
25
Claudel, Florian. "Development of anticorrosive Zn-based alloy coatings for cold formed steel body parts". Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0264.
Pełny tekst źródłaStreszczenie:
De nombreux revêtements sont utilisés par les constructeurs automobiles pour la protection contre la corrosion de pièces de carrosserie embouties à froid. D’après la littérature, diverses solutions et approches ont été suggérées au cours des dernières décennies. Cependant, seulement quelques systèmes ont pu aboutir à une production en série. L’objectif de la thèse de doctorat présentée ici est de développer et caractériser de nouveaux revêtements anticorrosifs à base d’alliages de zinc pour la protection contre la corrosion de composants en acier mis en forme à froid. Sur la base d’une revue de la littérature détaillée, deux approches d’intérêt ont été considérées, consistant en l’électrodéposition impulsionnelle de dépôts de ZnMn et de ZnMn-Al2O3. Les revêtements ont été caractérisés en termes de composition chimique, microstructure et cristallographie. L’aptitude des revêtements à une application dans l’industrie a été évaluée sur la base du comportement en corrosion, de la formabilité à froid et l’aptitude aux opérations de peintures. L’utilisation de l’électrodéposition impulsionnelle a permis d’obtenir des revêtements de ZnMn monophasés, absent de porosités et compacts, présentant une teneur en Mn avoisinant les 15 m.% avec un fort rendement. L’électrodéposition sur des substrats variés a révélé un procédé de déposition stable et reproductible. Des mesures électrochimiques et des tests de corrosion accélérés ont révélé une performance anticorrosive des alliages de ZnMn intéressante. Une amélioration du temps d’apparition de la rouille rouge et qu’une diminution de la vitesse de corrosion ont été observées en comparaison avec les revêtements traditionnels. Des analyses de la mise en forme à froid ont montré un comportement prometteur des dépôts de ZnMn. Des premiers tests de phosphatation et peinture ont démontré la bonne aptitude des revêtements pour ces procédés. Cependant, certaines limitations ont été identifiées avec notamment des propriétés insatisfaisantes des revêtements lors d’une immersion en milieu chloré. De plus, des porosités ont pu être observées à proximité de l’interface entre le dépôt et le substrat. Dans le but de résoudre ces problèmes, l’électrodéposition de revêtements composites ZnMn-Al2O3 a été considérée. L’impact des particules et des paramètres électriques sur la distribution des particules dans la matrice métallique a été étudié. Avec des paramètres optimisés, des dépôts composites homogènes, compacts et monophasiques contenant jusqu’à 15 m.% de Mn ont pu être obtenus avec de forts rendements. Des analyses poussées ont aussi révélé la présence de particules sur la surface ainsi qu’à l’interface substrat - film. Des premiers essais mécaniques ont montré une augmentation de la dureté des dépôts composites. Des mesures électrochimiques ont également donné un aperçu très prometteur sur le comportement anticorrosif des revêtements ZnMn-Al2O3Numerous coating systems are used by the automotive manufacturers for the corrosion protection of cold formed steel body parts. According to the literature, various approaches and solutions were suggested over the past decades. However, only a few systems were able to go into serial production. The objective of the present doctorate thesis is to develop and characterize alternative anticorrosive coatings based on Zn-alloys for the corrosion protection of cold formed steel components used for automotive body parts. Based on a thorough literature review, two interesting approaches were considered, consisting in the pulse electrodeposition of Zn-Mn and ZnMn-Al2O3 coatings. The deposits were characterized in order to determine their composition, microstructure as well as their crystallographic properties. The suitability of these new deposits was then assessed based on their anticorrosive behaviour, cold formability and paintability. Using pulse electrodeposition permitted to deposit monophasic, pore-free and compact Zn-Mn alloys containing about 15 wt.% Mn at high current efficiencies. Electrodeposition on various substrates exposed a stable and reproducible deposition process. Electrochemical experiments and accelerated corrosion tests revealed a promising anticorrosive performance of the Zn-Mn alloys. A substantial improvement in the time before red rust appearance and a significant decrease of the corrosion rate were observed in comparison to the traditional Zn deposits. While a slight increase of the hardness was observed in comparison to the Zn coatings, a lower crack density was observed on the Zn-Mn deposits after tensile experiments. Preliminary phosphating and painting tests revealed the good suitability of the Zn-Mn alloys for those processes with the formation of a dense and homogeneous phosphate crystals network and the successful deposition of a homogeneous and pore-free electrophoretic paint layer. However, some challenges were identified with Zn-Mn deposits presenting some unsatisfactory properties when immersed in chloride-containing environments. With the aim to solve these issues, the deposition of ZnMn-Al2O3 composite coatings was considered. The impact of the particles and electric parameters were investigated with a particular attention given to the distribution of the particles in the metallic matrix. Using optimized deposition parameters, homogeneous, compact and monophasic composite coatings containing about 15 wt.% Mn were obtained at high efficiencies. Further analyses revealed the presence of particles on the surface as well as at the substrate – deposit interface. First mechanical tests revealed interesting properties of the composite coatings with a substantial increase of the coating hardness. Electrochemical experiments also revealed some promising insights on the corrosion behaviour of the ZnMn-Al2O3 deposits
26
Wei, Zheng. "Metal release from stainless steel and CoCrMo alloys in protein-rich environments – effects of protein aggregation, friction, and irradiation". Licentiate thesis, KTH, Yt- och korrosionsvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-281787.
Pełny tekst źródłaStreszczenie:
Highly corrosion-resistant alloys are used in sensitive environments such as the human body and food environments. However, even tiny amounts of released metals from these surfaces could potentially cause adverse effects. It is hence important to study the biointerface between corrosion-resistant alloys and protein-rich environments. This licentiate thesis focused on the metal release processes for stainless steels and cobalt-chromium-molybdenum (CoCrMo) alloys in different protein-rich environments. It aimed at investigating the effect of protein displacement (Vroman effect), gamma irradiation, and friction on the metal release processes. Trace metal analysis was the main tool, combined with other solution analytical tools, electrochemical methods, and surface sensitive techniques. The effect of gamma irradiation, of relevance for cancer radiotherapy, on metal release from CoCrMo and stainless steel 316L was investigated in Paper I. The effect was minor, however the released amount of metals increased after irradiation causing an enhanced surface passivation effect. Whether the displacement of surface proteins (Vroman effect) was playing a role on the metal release and corrosion processes of stainless steels 316L and 303, and of CoCrMo, was investigated in Papers II and III. A Vroman effect influencing the metal release could be observed for stainless steel 316L, but not for CoCrMo and stainless steel grade 303. However, the displacement of the smaller protein bovine serum albumin (BSA) from the surface by the larger protein fibrinogen (Fbn) was observed for both stainless steel grades. The Vroman effect also caused a higher corrosion susceptibility of stainless steel 303, probably due to a thicker layer or patches of adsorbed Fbn. Most probably, protein aggregation and precipitation caused an underestimation of the extent of metal release, especially in the case of CoCrMo. Protein aggregation and precipitation were significantly observed in all studies, especially for solutions with high protein concentrations (Papers II-IV). The effect of friction, by using different setups (stirring with physical contact and sliding in a pin-on-disk machine), on metal release from stainless steel 316L and CoCrMo was investigated in Papers II and IV. Friction induced an increased extent of metal release, increased protein aggregation and precipitation, and enhanced metal precipitation. A combined friction and complexation effect was observed for stainless steel 316L, resulting in an etching effect and relatively high amounts of released metals. Due to enhanced precipitation effects and the experimental setup, it is recommended to strongly consider protein aggregation and metal precipitation events in systems where this could be expected and where friction is present. Otherwise, there is a risk to strongly underestimate the extent of metal release in these protein-rich environments.QC 2020-09-28
27
Squires, Lile P. "Friction Bit Joining of Dissimilar Combinations of Advanced High-Strength Steel and Aluminum Alloys". BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4104.
Pełny tekst źródłaStreszczenie:
Friction bit joining (FBJ) is a new method that enables lightweight metal to be joined to advanced high-strength steels. Weight reduction through the use of advanced high-strength materials is necessary in the automotive industry, as well as other markets, where weight savings are increasingly emphasized in pursuit of fuel efficiency. The purpose of this research is twofold: (1) to understand the influence that process parameters such as bit design, material type and machine commands have on the consistency and strength of friction bit joints in dissimilar metal alloys; and (2) to pioneer machine and bit configurations that would aid commercial, automated application of the system. Rotary broaching was established as an effective bit production method, pointing towards cold heading and other forming methods in commercial production. Bit hardness equal to the base material was found to be highly critical for strong welds. Bit geometry was found to contribute significantly as well, with weld strength increasing with larger bit shaft diameter. Solid bit heads are also desirable from both a metallurgical and industry standpoint. Cutting features are necessary for flat welds and allow multiple material types to be joined to advanced high-strength steel. Parameters for driving the bit were established and relationships identified. Greater surface area of contact between the bit and the driver was shown to aid in weld consistency. Microstructure changes resulting from the weld process were characterized and showed a transition zone between the bit head and the bit shaft where bit hardness was significantly increased. This zone is frequently the location of fracture modes. Fatigue testing showed the ability of FBJ to resist constant stress cycles, with the joined aluminum failing prior to the FBJ fusion bond in all cases. Corrosion testing established the use of adhesive to be an effective method for reducing galvanic corrosion and also for protecting the weld from oxidation reactions.
28
Clark, Tad Dee. "An Analysis of Microstructure and Corrosion Resistance in Underwater Friction Stir Welded 304L Stainless Steel". Diss., BYU ScholarsArchive, 2005. http://contentdm.lib.byu.edu/ETD/image/etd872.pdf.
Pełny tekst źródła
29
Le, Breton Jean-Marie. "Etude par spectrométrie Mössbauer de la corrosion d'alliages métalliques : aimants permanents Nd-Fe-B ; acier faiblement allié en eau de mer naturelle". Rouen, 1992. http://www.theses.fr/1992ROUES050.
Pełny tekst źródłaStreszczenie:
La spectrométrie Mössbauer du fer 57 a été utilisée en relation avec d'autres techniques (diffractions de rayons X, microscopie électronique à balayage, microsonde électronique) pour étudier la corrosion d'aimants permanents industriels Nd-Fe-B entre 90°C (avec humidité) et 400°C, et d'un acier faiblement allié (42CD4) en eau de mer naturelle en fonction de la pression hydrostatique. Dans les aimants Nd-Fe-B, l'évolution de la phase Nd2Fe1#4B a été plus particulièrement suivie. Cette phase semble disparaître sous l'effet de l'oxydation du Nd, en formant principalement du fer alpha. Un net ralentissement de ce processus a été mis en évidence dans les aimants avec Co et V préparés par décrépitation par l'hydrogène. La composition de la couche de rouille formée sur des plaques d'acier 42CD4 immergées en eau de mer naturelle pendant 15 jours ne varie pas pour des pressions supérieures à 3MPa. L'akaganéite n'est observée qu'aux pressions inferieures a 3MPa
30
Donohoe, C. J. "Corrosion fatigue of a high strength low alloy steel". Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322985.
Pełny tekst źródła
31
Hu, Xinming. "The corrosion and erosion-corrosion behaviour of high alloy stainless steels". Thesis, Heriot-Watt University, 2003. http://hdl.handle.net/10399/1160.
Pełny tekst źródła
32
TERADA, MAYSA. "Corrosão de aços inoxidáveis avançados em meios fisiológicos". reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11663.
Pełny tekst źródłaStreszczenie:
Made available in DSpace on 2014-10-09T12:54:28Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:07:42Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP
33
Walker, Nigel Stuart. "Type IV creep cavitation in low alloy ferritic steel weldments". Thesis, University of Bristol, 1997. http://hdl.handle.net/1983/efa6973c-9a3d-4a95-8297-61f12cbde92d.
Pełny tekst źródła
34
Evins, Joseph Lee. "Dependence of Strength on Corrosion-Fatigue Resistance of AISI 4130 Steel". Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5265.
Pełny tekst źródłaStreszczenie:
Automobile components are often exposed to aggressive environments as a result of aqueous salts from the road coming into contact with unprotected steel. This situation greatly reduces both the life and the appearance of the affected parts. Ultra-high strength steel parts are suspected to exhibit poor corrosion-fatigue properties and be more susceptible to corrosion in general.
In this study, the effect of strength level on the decrease in fatigue life of AISI 4130 steel when exposed to an aqueous salt solution is quantified. The observed mechanical properties including corrosion-fatigue behavior are examined with consideration to different microstructural characteristics resulting from heat treatments to the steel. The hardness and tensile properties of the test material were characterized before fatigue testing. Fatigue tests were completed in both air and salt solution to determine the effect on fatigue life of the latter environment. Following fatigue testing, the fracture surface was examined using a scanning electron microscope (SEM) to determine the failure mode.
Six strength levels of AISI 4130 steel were investigated ranging from 837 to 1846 MPa (121 268 ksi). The frequency of loading used for corrosion-fatigue tests was 1 Hz and the stress ratio for each test was constant at R = 0.1. The corrosion-fatigue tests consisted of the specimen being submerged in an aqueous solution of sodium chloride, calcium chloride, and sodium bicarbonate and fatigued until failure. The solution was maintained at room temperature with constant aeration to ensure constant oxygen levels. The parameters of interest were the applied loads and the cycles to failure.
There were four primary findings of the study. First, decreases in fatigue life of the material caused by the corrosive environment ranged from 100% in the lowest strength level to 190% in the higher strength levels. This result showed that higher strength in this steel corresponds to increasing detriment to fatigue life when the material is exposed to an aqueous salt environment. Second, evidence was found that the salt solution lowered the fatigue limit for each strength level studied in this material. All specimens that were tested in the corrosive environment failed in less than 150,000 cycles, while some specimens fatigued in the air environment experienced run-outs at over 106 cycles. Third, the decrease in fatigue life was attributed to the presence of martensite in the structure of the steel. It was noted that the higher the martensite content, the larger the decrease in fatigue life when exposed to the corrosive environment. Finally, the fracture surfaces of fatigued specimens revealed that a similar cracking mode was present for each strength level in both environments. Enhanced crack initiation was, therefore, assumed to be the cause of the decrease in fatigue life between the air and aqueous salt environments.
35
Anyanwu, Ezechukwu John. "Low Alloy Steel Susceptibility to Stress Corrosion Cracking in Hydraulic Fracturing Environment". University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1398948610.
Pełny tekst źródła
36
Ozcan, Emre. "Corrosion Behaviors Of Stainless Steels In Molten Zinc Aluminum Alloy". Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614565/index.pdf.
Pełny tekst źródłaStreszczenie:
High grade galvanized steel in large amounts is needed to match the increasing
demand of automotive industry both in our country and in the world. Stainless steels,
used in fabrication of zinc bath hardware of continuous galvanizing lines, lose their
corrosion resistance due to various mechanisms in such mediums containing molten
metals like zinc and aluminum. Consequently they corrode to the levels where they
should be taken to maintenance or replaced. In this study, corrosion performance and
the effect of typical galvanizing and age treating heat treatments to mechanical
properties of 4 newly developed austenitic stainless steels and AISI 316L grade
stainless steel were investigated and compared with each other. Experimental studies
involved immersion corrosion tests for 168 and 504 hours followed by weight loss
determinations and comparisons of corrosion performances of age treated and
solution annealed stainless steels. Parallel with corrosion testing, delta ferrite content
v
determinations with 3 different methods, tensile tests and v-notch impact tests at 4
different heat exposure conditions were carried out and discussed. 2 new stainless
steel compositions were selected to be used in fabrication of galvanizing hardware
based on the comparisons of corrosion &mechanical performances of candidate steels.
37
Sapiro, David O. "The Effects of Alloy Chemistry on Localized Corrosion of Austenitic Stainless Steels". Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1087.
Pełny tekst źródłaStreszczenie:
This study investigated localized corrosion behavior of austenitic stainless steels under stressed and unstressed conditions, as well as corrosion of metallic thin films. While austenitic stainless steels are widely used in corrosive environments, they are vulnerable to pitting and stress corrosion cracking (SCC), particularly in chloride-containing environments. The corrosion resistance of austenitic stainless steels is closely tied to the alloying elements chromium, nickel, and molybdenum. Polarization curves were measured for five commercially available austenitic stainless steels of varying chromium, nickel, and molybdenum content in 3.5 wt.% and 25 wt.% NaCl solutions. The alloys were also tested in tension at slow strain rates in air and in a chloride environment under different polarization conditions to explore the relationship between the extent of pitting corrosion and SCC over a range of alloy content and environment. The influence of alloy composition on corrosion resistance was found to be consistent with the pitting resistance equivalent number (PREN) under some conditions, but there were also conditions under which the model did not hold for certain commercial alloy compositions. Monotonic loading was used to generate SCC in in 300 series stainless steels, and it was possible to control the failure mode through adjusting environmental and polarization conditions. Metallic thin film systems of thickness 10-200 nm are being investigated for use as corrosion sensors and protective coatings, however the corrosion properties of ferrous thin films have not been widely studied. The effects of film thickness and substrate conductivity were examined using potentiodynamic polarization and scanning vibrating electrode technique (SVET) on iron thin films. Thicker films undergo more corrosion than thinner films in the same environment, though the corrosion mechanism is the same. Conductive substrates encourage general corrosion, similar to that of bulk iron, while insulating substrates supported only localized corrosion.
38
Boerstler, Joshua Trevitt. "Corrosion Degradation of Coated Aluminum Alloy Systems through Galvanic Interactions". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524185375873158.
Pełny tekst źródła
39
Stratulat, Alisa. "Micromechanics of stress corrosion cracking in 304 stainless steel and Ni Alloy 600". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:3c150765-b2b1-4f54-95aa-36d294a99acc.
Pełny tekst źródłaStreszczenie:
The current thesis takes a step forward into understanding the intergranular stress corrosion cracking (IGSCC) by applying a relatively new micro-mechanical technique to look at the crack growth rate of individual grain boundaries in 304 stainless steel (SS) and to measure fracture toughness for different grain boundaries in Ni Alloy 600. In addition, a model is tested and proposed that could predict crack initiation in 304 SS. Pentagonal cross-section cantilevers 5 μm wide by 25 μm long were milled at individual grain boundaries in both 304 SS and Ni Alloy 600. The cantilevers milled in 304 SS were tested in-situ in a customised stage, using the nanoindenter. Crack growth rate was measured for two different cantilevers to be approximately 40 μm/s (K = 1.1 MPa(m)^(1/2)) and 120 μm/s (K = 1.7 MPa(m)^(1/2)). Cantilevers were milled in Ni Alloy 600 for three different samples: samples that were exposed to simulated pressurized water reactors (PWR) environment for 4500 h, for 1500 h and un-oxidised samples. The fracture toughness calculated for the fractured cantilevers in samples that were exposed for 4500 h was measured to be between 0.73 and 1.82 MPa(m)^(1/2). No intergranular fracture occurred in the samples that were exposed for 1500 h and in the un-oxidised samples. The grain boundary misorientation was measured for the tested cantilevers but no direct correlation was observed between the misorientation angle and the fracture toughness. A Schmid-modified grain boundary stress (SMGBS) model previously used to study the intergranular behaviour of irradiated 316L steel in supercritical water was applied to predict crack initiation in 304 stainless steel. The model was successfully applied and accurately predicted crack initiation. To extend the model, sensitisation was also included. In addition, different areas of the specimen, including the initiation site were analysed using High resolution electron backscatter diffraction (HR-EBSD) technique to measure the geometrically necessary dislocations (GNDs) density. It was observed that the boundary average GNDs is lower for the intact boundaries and higher for the cracked grain boundaries.
40
Feng, Zhicao. "Galvanic Corrosion of Coated Al Alloy Panels with More Noble Fasteners". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1436781873.
Pełny tekst źródła
41
Wilson, Peter. "Remanent creep life prediction in low-alloy ferritic steel power plant components". Thesis, University of Cambridge, 1991. https://www.repository.cam.ac.uk/handle/1810/221887.
Pełny tekst źródła
42
Ioannou, John. "Mechanical behaviour and corrosion of interstitial-free steel-aluminium alloy self-piercing riveted joints". Thesis, University of Hertfordshire, 2010. http://hdl.handle.net/2299/4611.
Pełny tekst źródłaStreszczenie:
The overall aim of the project is to examine the rivetability of new steels and to investigate the mechanical behaviour of self-piercing riveted (SPR) aluminium-steel hybrid structures for automotive applications. Interstitial Free Steel (I.F.) of 1.2 mm thickness was joined to Aluminium 5754 of 2 mm thickness and Aluminium 5182 (coated and uncoated) of 1.5 mm thickness. The work began by initially conducting a quality assessment of the various joints that were produced in order to establish the optimum conditions for joining the various sample combinations to be investigated. A relationship was established between the head height and the interlock distance on the one hand and between the interlock distance and the lap shear strength of samples. It was also established that for higher lap shear strength, it is preferable to use the stronger material (I.F. steel) as the pierced sheet and the weaker material (5182) as the locked sheet. However, the results showed that this rule could not be applied for predicting the fatigue behaviour of SPR joints between I.F. steel and 5182. An investigation of the fatigue failure mechanisms was undertaken and possible reasons for this behaviour are discussed. The influence of fretting was also investigated by using scanning electron microscopy and reported. The fatigue behaviour of Dual Phase (DP600 + 5182) SPR joints was investigated. It was observed that the position of fatigue crack initiation differed with the maximum applied load. An explanation for this observation was provided by considering the failure mechanism of the samples under different load levels. The study also showed how fretting led to the initiation of fatigue cracks. The corrosion behaviour of (I.F. steel + 5182) samples was investigated by conducting tests in a salt spray according to the ASTM B117-97 standard. Three types of corrosion were observed; galvanic corrosion, differential aeration corrosion, uniform corrosion and are discussed. The weight change with time was monitored and was used to describe the corrosion behaviour. The lap shear strength was measured as a function of corrosion time. The presence of the corrosion product within the overlap was observed to greatly influence the lap shear strength behaviour. A further study was carried out in order to examine the influence of the individual alloys on the corrosion of the SPR samples. In this part the potential influence of pulse current treatment on corrosion was also investigated and was observed to increase greatly the corrosion resistance of the I.F. steel. Principal findings for this observation are also provided.
43
Needham, William Donald. "Stress corrosion cracking and hydrogen embrittlement of thick section high strength low alloy steel". Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/10945/22123.
Pełny tekst źródłaStreszczenie:
An experimental study was conducted to evaluate the corrosion performance of weldments of a high strength low alloy(HSLA) steel in a simulated seawater environment. This steel, designated HSLA80, was developed by the United States Navy for use in ship structural applications. Stress corrosion CRACKING(SCC) and hydrogen embrittlement(HEM) were investigated by conducting 42 Wedge-Opening load(WOL) tests as a function of stress intensity and corrosion potential and 33 Slow Strain Rate(SSR) tests as a function of strain rate and corrosion potential. The corrosion potentials were chosen to simulate the environmental conditions of free corrosion, cathodic protection and hydrogen generation. The results from this investigation indicated that HSLA 80 base metal and weldments were susceptible to hydrogen assisted cracking(HAC) in a seawater environment under conditions of continuous plastic deformation and triaxial stress in the presence of hydrogen. The heat-affected zone of the weldment was found to be the most susceptible portion of the weld joint. A lower bound was established for the critical stress intensity for stress corrosion cracking for HSLA 80 base metal and weldments.(Theses)
44
Holden, Nicholas John. "The improvement of weld quality in medium frequency direct current resistance spot welding". Thesis, Birmingham City University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312224.
Pełny tekst źródłaStreszczenie:
Zinc coated steels are widely used in the automotive industry, because of the improved protection against corrosion. Their use has consequences for the resistance welding process, which is the most widely used method of joining body panels. The zinc coating alloys with the copper electrode, resulting in increased electrode wear, and a reduction in electrode life. The welding current must be increased, because of the reduced contact resistance and thus heavier cables and power sources are required. A novel form of power source, the Medium Frequency Direct Current inverter, offers advantages over the traditional AC transformer. The higher operating frequency results in a lighter transformer, and a smaller welding current may be used, because the DC welding current generates heat at a constant rate, and is thus more effective than an AC power source. A potential advantage of this technology is that the increased frequency allows improved resolution in monitoring and control. Novel signal conditioning circuitry was developed, allowing significant improvement in the time resolution of the voltage and resistance signals. A series of welding trials was conducted, while monitoring the welding process. The correlation between weld quality and various process variables was assessed, and a control algorithm to compensate for electrode wear was proposed. This algorithm, based on a constant voltage principle, was implemented on a bespoke welding timer. A significant improvement in electrode life was obtained using this technique. The control algorithm was shown effective experimentally, but practical limitations do not permit testing under all possible conditions. A numerical model of the spot welding process, using Finite Difference technique, was developed. Following successful validation, the model was used to predict the performance of the control algorithm under various conditions of electrode wear. The results indicate that a constant voltage algorithm can compensate for an increase in electrode tip diameter, but that a change in contact resistance may result in unsatisfactory welds.
45
Challis, M. R. "Improved corrosion resistance in zinc and zinc aluminium alloy galvanised strip steels". Thesis, Swansea University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636221.
Pełny tekst źródłaStreszczenie:
The research detailed in this thesis addresses two major challenges facing the performance of organically coated galvanised steels (OCS); namely, improving corrosion and environmental performance. The project aimed to address the viability of chromium free inhibitor chemistries and new metallic coating chemistries with a view to producing organic coated steel products for construction with superior performance. The future of OCS materials depends on the removal of hexavalent chromium from conversion coatings and inhibitor systems. Scanning electrochemical techniques have been developed to provide spatially resolved current intensity measurement and by a series of mathematical treatments semi-quantitative estimates of corrosion. The studies have shown that whilst anodic inhibitors (Cr2O42-, MoO42-, PO42-) can elevate corrosion intensity on zinc galvanised steel they appear far more efficient on the more corrosion resistant Galfan (4.2% Al). By contrast cathodic inhibitors based on REM cations (Ce3+, Y3+, La3+) are efficient on both substrates. The difference is related to the heterogeneous microstructure of the Galfan coating. Despite improved corrosion performance the heterogeneous microstructure of the Galfan coating leads to corrosion localisation at zinc rich dendrites. Galfan samples (2.4% Al) differing only in the spelter addition of trace magnesium levels (0.01% to 0.05%) were studied using the SVET. For the bare substrate reduced surface cracking and dendrite breakthrough reduced surface corrosion activity as magnesium levels increased. By contrast increasingly large sub surface dendrites caused a rapid increase in cut edge corrosion intensity. Chromium free OCS samples were prepared using novel primer pigments based on clay minerals ion exchanged with REM cations incorporated into a PVC plastisol primer and applied to a Galfan substrate pre-treated with a phosphate coating. The REM exchanged clay materials performed equivalent to or better than the best available chrome free pigment, calcium exchanged silica. In combination with improved metallic coating chemistry these materials are likely to provide the high performance coated products of tomorrow.
46
Sapiro, David O. "The Effects of Alloy Chemistry on Localized Corrosion of Austenitic Stainless Steels". Thesis, Carnegie Mellon University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10639516.
Pełny tekst źródłaStreszczenie:
This study investigated localized corrosion behavior of austenitic stainless steels under stressed and unstressed conditions, as well as corrosion of metallic thin films. While austenitic stainless steels are widely used in corrosive environments, they are vulnerable to pitting and stress corrosion cracking (SCC), particularly in chloride-containing environments. The corrosion resistance of austenitic stainless steels is closely tied to the alloying elements chromium, nickel, and molybdenum. Polarization curves were measured for five commercially available austenitic stainless steels of varying chromium, nickel, and molybdenum content in 3.5 wt.% and 25 wt.% NaCl solutions. The alloys were also tested in tension at slow strain rates in air and in a chloride environment under different polarization conditions to explore the relationship between the extent of pitting corrosion and SCC over a range of alloy content and environment. The influence of alloy composition on corrosion resistance was found to be consistent with the pitting resistance equivalent number (PREN) under some conditions, but there were also conditions under which the model did not hold for certain commercial alloy compositions. Monotonic loading was used to generate SCC in in 300 series stainless steels, and it was possible to control the failure mode through adjusting environmental and polarization conditions. Metallic thin film systems of thickness 10-200 nm are being investigated for use as corrosion sensors and protective coatings, however the corrosion properties of ferrous thin films have not been widely studied. The effects of film thickness and substrate conductivity were examined using potentiodynamic polarization and scanning vibrating electrode technique (SVET) on iron thin films. Thicker films undergo more corrosion than thinner films in the same environment, though the corrosion mechanism is the same. Conductive substrates encourage general corrosion, similar to that of bulk iron, while insulating substrates supported only localized corrosion.
47
Mohamed, Abdul Aziz Bin. "Creep life prediction of low alloy steel using neural network analysis of NDT". Thesis, Cranfield University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266946.
Pełny tekst źródła
48
Davies, David Phillip. "Fatigue behaviour of gas-carburised, temper-resistant, low-alloy steels". Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321168.
Pełny tekst źródła
49
Millar, Peter G. "Corrosion fatigue crack propagation behaviour of a high strength low alloy steel in a synthetic sea water environment". Thesis, Cranfield University, 1986. http://dspace.lib.cranfield.ac.uk/handle/1826/4443.
Pełny tekst źródłaStreszczenie:
The corrosion fatigue crack propagation behaviour of a high strength low alloy steel, N-A-XTRA 70, in a synthetic sea water solution was tested using S. E. N. specimens subjected to a loading frequency of 0.1 Hz and a load ratio of 0.6. In order to simulate the conditions encountered by a thumbnail type crack several specimens from each of the microstructural types tested, namely parent plate, heat affected zone and heat treated material, had their crack sides covered by transparent plastic covers. Severe overprotection and slight underprotection conditions were produced using cathodic protection potentials of -1400, -1300, -1200 and -700 mV (S. C. E. ). The Paris relationship da/dN = CLKm was found to be a useful tool in describing the crack propagation rate data. Results obtained, presented in the form of plots of log da/dN against log AK, show that for parent plate, H. A. Z. and heat treated material, covering the crack sides of specimens produces enhanced corrosion fatigue crack propagation rates, at cathodic protection potentials of -1400 and -1300 mV (S. C. E. ), when compared to non covered specimens. This trend was also true for H. A. Z. specimens at a potential of -700 mV (S. C. E. ). For parent plate specimens, however, covering the crack sides at a potential of -700 mV (S. C. E. ) produced reduced crack propagation rates over non covered specimens. It is believed restriced oxygen access may account for these results. Plots of the Paris exponent m and constant C for the three microstructures tested produced three lines of the form m= alnC +b where a and b were found to be dependent upon material parameters. Comparison of results with BS 4360: 50D revealed that N-A-XTRA 70 exhibited superior fatigue performance when tested in air but behaved worse under conditions of free corrosion.
50
Laws, Paul. "Corrosion fatigue performance of welded high strength low alloy steels for use offshore". Thesis, Cranfield University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359541.
Pełny tekst źródła