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1
Stradomski, Z., S. Stachura, and G. Stradomski. "Fracture Mechanisms in Steel Castings." Archives of Foundry Engineering 13, no. 3 (September 1, 2013): 88–91. http://dx.doi.org/10.2478/afe-2013-0066.
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Abstract The investigations were inspired with the problem of cracking of steel castings during the production process. A single mechanism of decohesion - the intergranular one - occurs in the case of hot cracking, while a variety of structural factors is decisive for hot cracking initiation, depending on chemical composition of the cast steel. The low-carbon and low-alloyed steel castings crack due to the presence of the type II sulphides, the cause of cracking of the high-carbon tool cast steels is the net of secondary cementite and/or ledeburite precipitated along the boundaries of solidified grains. Also the brittle phosphor and carbide eutectics precipitated in the final stage solidification are responsible for cracking of castings made of Hadfield steel. The examination of mechanical properties at 1050°C revealed low or very low strength of high-carbon cast steels.
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Wang, Wenbin, Li Xiong, Dan Wang, Qin Ma, Yan Hu, Guanzhi Hu, and Yucheng Lei. "A New Test Method for Evaluation of Solidification Cracking Susceptibility of Stainless Steel during Laser Welding." Materials 13, no. 14 (July 16, 2020): 3178. http://dx.doi.org/10.3390/ma13143178.
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A new test method named “Trapezoidal hot” cracking test was developed to evaluate solidification cracking susceptibility of stainless steel during laser welding. The new test method was used to obtain the solidification cracking directly, and the solidification cracking susceptibility could be evaluated by the solidification cracking rate, defined as the ratio of the solidification cracking length to the weld bead length under certain conditions. The results show that with the increase in the solidification cracking rate, the solidification cracking susceptibility of SUS310 stainless steel was much higher than that of SUS316 and SUS304 stainless steels during laser welding (at a welding speed of 1.0 m/min) because a fully austenite structure appeared in the weld joint of the former steel, while the others were ferrite and austenitic mixed structures during solidification. Besides, with an increase in welding speed from 1.0 to 2.0 m/min during laser welding, the solidification cracking susceptibility of SUS310 stainless steel decreased slightly; however, there was a tendency towards an increase in the solidification cracking susceptibility of SUS304 stainless steel due to the decrease in the amount of ferrite under a higher cooling rate.
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Stradomski, G. "The Cracking Mechanism of Ferritic-Austenitic Cast Steel." Archives of Foundry Engineering 16, no. 4 (December 1, 2016): 153–56. http://dx.doi.org/10.1515/afe-2016-0101.
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Abstract In the high-alloy, ferritic - austenitic (duplex) stainless steels high tendency to cracking, mainly hot-is induced by micro segregation processes and change of crystallization mechanism in its final stage. The article is a continuation of the problems presented in earlier papers [1 - 4]. In the range of high temperature cracking appear one mechanism a decohesion - intergranular however, depending on the chemical composition of the steel, various structural factors decide of the occurrence of hot cracking. The low-carbon and low-alloy cast steel casting hot cracking cause are type II sulphide, in high carbon tool cast steel secondary cementite mesh and / or ledeburite segregated at the grain solidified grains boundaries, in the case of Hadfield steel phosphorus - carbide eutectic, which carrier is iron-manganese and low solubility of phosphorus in high manganese matrix. In duplex cast steel the additional factor increasing the risk of cracking it is very “rich” chemical composition and related with it processes of precipitation of many secondary phases.
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TUMULURU, MURALI. "Effect of Silicon and Retained Austenite on the Liquid Metal Embrittlement Cracking Behavior of GEN3 and High-Strength Automotive Steels." Welding Journal 98, no. 12 (December 1, 2019): 351s—364s. http://dx.doi.org/10.29391/2019.98.029.
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GEN3 steels are a new family of automotive sheet steels developed and commercialized in the last three years, specifically for body-in-white applications. The high ductility in GEN3 steels is typically achieved through the transformation-induced plasticity (TRIP) effect by the addition of silicon or aluminum. When these steels are formed into parts, the TRIP effect of austenite to martensite transformation provides enhanced ductility. Typically, 10 to 12 micrometers of zinc coating (known as galvanized coating) is applied to automotive steel sheets for corrosion protection. Liquid metal embrittlement (LME) cracking can occur during resistance spot welding (RSW) of galvanized steels. LME cracking occurs when molten zinc penetrates prior austenite grain boundaries of the steel substrate. The precise role of silicon in the LME cracking behavior in TRIP and GEN3 steels is unknown. Therefore, a study was undertaken to examine the role of silicon in LME cracking behavior of GEN3 steels. The purpose was also to examine if the presence of retained austenite is required for LME cracking to occur. In this study, laboratory heats were prepared using three silicon levels. Samples cut from galvanized panels were welded using a resistance spot welding machine, and weld areas were examined metallographically for the presence of LME cracks. Gleeble® simulations were done to study the LME behavior of the three steels prepared. Base materials were examined with a scanning electron microscope using the electron back-scattered diffraction (EBSD) method to examine the nature of grain boundaries found. The effect of retained austenite in LME cracking was studied using the Gleeble®. Both RSW and Gleeble® results showed silicon promotes LME cracking in steels, predominantly in the weld heat-affected zones(HAZs). More low-energy, low-coincidence site lattice (CSL) boundaries were found as the silicon content of the steel was decreased. These boundaries do not host cracks. Higher silicon appeared to shrink the safe temperature range over which LME cracks could be avoided, thus indicating heat in-put control to limit cracks has limited windows as the silicon in steel goes up. It was shown that the presence of retained austenite in steel is not a prerequisite for LME cracking to occur.
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Terasaki, F., H. Ohtani, A. Ikeda, and M. Nakanishi. "Steel Plates for Pressure Vessels in Sour Environment Applications." Proceedings of the Institution of Mechanical Engineers, Part A: Power and Process Engineering 200, no. 3 (August 1986): 141–58. http://dx.doi.org/10.1243/pime_proc_1986_200_021_02.
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It is well known that wet hydrogen sulphide (H2S) can cause embrittlement of steels, hydrogen induced cracking (HIC) and sulphide stress corrosion cracking (SSCC). Several fractures of pipelines handling sour crude oil or gas led to vigorous researches on these problems. As similar failures have also been experienced in petroleum refinery equipment, degradation of steel by hydrogen sulphide is now recognized as a serious environmental problem. The paper considers the mechanism and factors involved in HIC. This type of cracking occurs mainly in the parent steels. The susceptibility of steels to cracking is influenced strongly by inhomogeneities such as the shape and distribution of non-metallic inclusions, and segregation of alloying elements. These have a significant effect on HIC because they modify the microstructures in the segregated regions. With reference to environmental factors, these mainly concern the influence of H2S partial pressures, pH of the solutions and other phenomena relevant to the absorption of hydrogen by the steel. SSCC poses problems in weld zones. It can occur especially in heat affected zones (HAZ) with high hardnesses. Such cracking can be prevented by the control of hardness by a suitable selection of the chemical composition of the steel and the welding conditions. Nevertheless, countermeasures similar to those described for the prevention of HIC are necessary to prevent SSCC in HAZ even with relatively low hardness. Research on factors influencing HIC and SSCC has resulted in the development of steels which are highly resistant to wet H2S cracking. These steels have been supplied in plate form for pressure vessels. Experience has confirmed the good performance of welded constructions in aggressive service environments.
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Jones, R., and S. C. Forth. "Cracking in D6ac steel." Theoretical and Applied Fracture Mechanics 53, no. 1 (February 2010): 61–64. http://dx.doi.org/10.1016/j.tafmec.2009.12.005.
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Fydrych, Dariusz, Jerzy Łabanowski, and Grzegorz Rogalski. "Weldability of high strength steels in wet welding conditions." Polish Maritime Research 20, no. 2 (April 1, 2013): 67–73. http://dx.doi.org/10.2478/pomr-2013-0018.
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Abstract In this paper are characterized problems of high strength steel weldability in underwater wet welding conditions. Water as a welding environment intensifies action of unfavourable factors which influence susceptibility to cold cracking of welded steel joints. The susceptibility to cold cracking of S355J2G3 steel and S500M steel in wet conditions was experimentally estimated (by using Tekken test). It was concluded that the steels in question are characterized by a high susceptibility to formation of cracks in welds. Usefulness of the proposed Temper Bead Welding technique (TBW) was experimentally verified as a method for improving weldability of the steels in the analyzed conditions.
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Kong, Fan Yu. "Research on Test about Stress Corrosion Cracking of SPV50Q Spherical Tank." Advanced Materials Research 284-286 (July 2011): 2437–41. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.2437.
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SPV50Q steel belongs to high-alloyed steel that is widely used to fabricate storage tank for liquefied petroleum gas. However, it has a great tendency to the problem of environmental cracking under the service condition of LPG containing wet sulfide hydrogen surpassing the lowest allowance for steels. In order to quantitatively evaluate the cracking susceptibility on this steel in the wet H2S environment, the pre-fatigue crack M-WOL specimen stress corrosion cracking tests in three H2S concentrations were performed under the different welding conditions, and in safety performance analysis of equipment, and preventing countermeasure had been proposed. The method could be extended forecasting accident in LPG SCC.
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Joseline, Dyana, Radhakrishna G. Pillai, and Lakshman Neelakantan. "Initiation of Stress Corrosion Cracking in Cold-Drawn Prestressing Steel in Hardened Cement Mortar Exposed to Chlorides." Corrosion 77, no. 8 (May 28, 2021): 906–22. http://dx.doi.org/10.5006/3730.
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Cold-drawn, high-strength, prestressing (PS) steel strands are widely used in pretensioned concrete (PTC) structures. This paper discusses the stress corrosion cracking (SCC) of PS steel embedded in cement mortar and gradually exposed to chlorides. Various stages of the passive to active (P-to-A) transition, which marks the onset of SCC, were investigated using the electrochemical impedance spectroscopy technique. The key mechanisms were identified and confirmed using scanning electron microscopy/energy dispersive x-ray analysis, x-ray diffarction, and confocal Raman spectroscopy. It was found that the passive film on unstressed PS steel has better electrochemical characteristics than that on conventional steel rebars. However, the residual tensile stress at the surface of PS steels can assist passive film cracking after chloride attack—contrary to the pitting corrosion without cracking of passive film in conventional steels. Further, tests indicated that the concentration of chlorides required to crack the passive film in PS steels can reduce by about 50% when prestressed—as in field structures. Chemical composition, stress state, and microstructural features at the PS steel surface were identified as possible factors influencing the initiation of SCC in PTC structures.
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Cheng, Xiao Ying, Hong Yuan Chen, Wen Qing Liu, and Zhi Juan Zhang. "Influence of Mooring Chain Steel Strength on Stress Corrosion Cracking." Applied Mechanics and Materials 404 (September 2013): 32–39. http://dx.doi.org/10.4028/www.scientific.net/amm.404.32.
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Two strength mooring chain steels were used to investigate the stress corrosion cracking (SCC) in synthetic seawater. The resistance of both strength steels to SCC was similar in neutral synthetic seawater. But the failure mechanism was different. For lower strength steel, it is mainly induced by anodic dissolution, while for higher strength steel, by hydrogen embrittlement. The reason was elucidated from their microstructures and corrosion characteristics.
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Kunishige, Kazutoshi, and Masaharu Hatano. "Surface Hot-Shortness of Steels Induced by a Small Amount of Copper and Tin from Scrap Steels and its Suppression Methods." Materials Science Forum 539-543 (March 2007): 4113–18. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.4113.
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The recycling of scrap steels can be difficult due to the tramp elements that they can contain. During the steelmaking process, tramp elements such as Cu and Sn are difficult to be removed; and it is these elements that cause surface cracking of steels during hot rolling process (i.e. Cu and Sn liquid embrittlement).The paper consists of three different experiments into the suppression of surface cracking during the hot rolling process. For the oxidation in air, the surface cracking most severely occurred in the specimens which were oxidized around 1100°C in the tested range of 950-1200°C after a 1250°C heating. For the change in oxidation atmosphere from air to water vapor, the surface cracking occurred more severely although the mass gains were smaller in water vapor than in air oxidation. For the addition of Si and Ni in the water vapor conditions of 0%-30%H2O, the surface cracking was found to be suppressed effectively when the mass gain increased. The Cu and Sn enriched alloys at the scale/steel interface were closely observed by optical microscopy and scanning electron microscopy. The mechanism for suppression of the surface cracking was explained in terms of back diffusion of Cu and Sn into the steel and/or occlusion of Cu and Sn into the scale through the development of a rugged scale/steel interface.
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Naumenko, V. V., G. A. Filippov, A. P. Shlyamnev, and I. P. Shabalov. "Corrosion cracking of alloy steel." Steel in Translation 41, no. 12 (December 2011): 1033–39. http://dx.doi.org/10.3103/s0967091211120102.
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Topolska, S., and J. Łabanowski. "Environmental Degradation of Dissimilar Austenitic 316L and Duplex 2205 Stainless Steels Welded Joints." Archives of Metallurgy and Materials 62, no. 4 (December 1, 2017): 2107–12. http://dx.doi.org/10.1515/amm-2017-0312.
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AbstractThe paper describes structure and properties of dissimilar stainless steels welded joints between duplex 2205 and austenitic 316L steels. Investigations were focused on environmentally assisted cracking of welded joints. The susceptibility to stress corrosion cracking (SCC) and hydrogen embrittlement was determined in slow strain rate tests (SSRT) with the strain rate of 2.2 × 10−6s−1. Chloride-inducted SCC was determined in the 35% boiling water solution of MgCl2environment at 125°C. Hydrogen assisted SCC tests were performed in synthetic sea water under cathodic polarization condition. It was shown that place of the lowest resistance to chloride stress corrosion cracking is heat affected zone at duplex steel side of dissimilar joins. That phenomenon was connected with undesirable structure of HAZ comprising of large fractions of ferrite grains with acicular austenite phase. Hydrogen assisted SCC tests showed significant reduction in ductility of duplex 2205 steel while austenitic 316L steel remains almost immune to degradation processes. SSR tests of dissimilar welded joints revealed a fracture in the area of austenitic steel.
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Huang, Weishan, Jing-Li Luo, Hani Henein, and Josiah Jordan. "Sulfide stress cracking assessment of low-alloy L80 casing steel in H2S environment." Anti-Corrosion Methods and Materials 66, no. 4 (July 1, 2019): 379–87. http://dx.doi.org/10.1108/acmm-08-2018-1984.
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Purpose This paper aims to evaluate the sulfide stress cracking (SSC) resistance of L80 casing steels with different alloying chemistries (e.g. Ti-B and Mn-Cr-Mo) by correlating the reduction in area ratio with the mechanical property, inclusion and carbide. Design/methodology/approach SSC tests were conducted in 5.0 Wt.% sodium chloride and 0.5 Wt.% acetic acid solution saturated with H2S using constant load tensile method. The microstructure and fracture morphology of the steel were observed using scanning electron microscope. The inclusion and carbide were identified by energy dispersive spectroscopy and auger electron microscope. Findings Among all the testing steels, electric resistance welding (ERW) L80-0.5Mo steel demonstrates the highest SSC resistance because of its appropriate mechanical properties, uniform microstructure and low inclusion content. The SSC resistance of L80 steels generally decreases with the rising yield strength. The fracture mode of steel with low SSC resistance is jointly dominated by transgranular and intergranular cracking, whereas that with high SSC resistance is mainly transgranular cracking. SSC is more sensitive to inclusions than carbides because the cracks are easier to be initiated from the elongated inclusions and oversized oxide inclusions, especially the inclusion clusters. Unlike the elongated carbide, globular carbide in the steel can reduce the negative effect on the SSC resistance. Especially, a uniform microstructure with fine globular carbides favors a significant improvement in SSC resistance through precluding the cracking propagation. Originality/value The paper provides the new insights into the improvement in SSC resistance of L80 casing steel for its application in H2S environment through optimizing its alloying compositions and microstructure.
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Negi, B. S. "Case Studies on Field Repairs of Stainless Steel Components in Refinery." Advanced Materials Research 794 (September 2013): 375–79. http://dx.doi.org/10.4028/www.scientific.net/amr.794.375.
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Stainless steels (SS) possess excellent corrosion, creep and high temperature oxidation resistance and are invariably used in refinery for construction of heater tubes, tube supports, Heat exchanger bundles, piping and internal lining of pressure vessels. Ferritic stainless steel type 405 is used for column strip-lining, martensitic stainless steel type 410 is used for column trays and heater tubes and austenitic stainless steel family is used very extensively for lining, piping, heat exchanger, heater tubes and tube supports. On-stream and turnaround condition monitoring of plant and equipment are carried out for health assessment and mitigation of premature failure. However, catastrophic failures of stainless steel due to stress corrosion cracking, thermal fatigue and stress relaxation cracking are encountered in addition to bulging and cracking of strip-lining. Field repairs of these components are required to be done. Stainless steels are difficult to weld due to low thermal conductivity, higher coefficient of thermal expansion, fissuring and solidification cracking problem during welding. Lower heat input and fast cooling facilitate the welding process. Welding of service exposed stainless steels is more challenging, as it has already undergone metallurgical degradation. Welding of stainless steels is carried out using TIG and SMAW process with matching electrode after establishing the welding specification procedures and welders qualification. Field repairs of stainless steels components are also attempted with original procedures and in case of difficulties, a buttering layer of inconel (ERNiCr3) or ER 309Mo is provided on the welding surface before using matching electrodes. Quality assurance of weld joint is ensured by stage-wise inspection and non-destructive testing. Dye penetrant test of root run and radiographic examination of final weld joint are most common. Post weld heat treatment is done as per code requirement. This Paper highlights three case studies on field repairs of stainless steel components in refinery. 1. Welding procedure followed for repair of bulged and cracked SS 316 strip-lining and cladding on carbon steel backing material. It is a dissimilar welding of SS 316L with degraded carbon steel. 2. Field welding of SS 347 Piping components, which has undergone thermal relaxation cracking at fillet joints. 3. Welding repair of SS 310 cast heater tube support conforming to A 297 Gr HK 40. The Paper also presents brief failure analysis with reasons and remedies.
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Kong, Fan Yu, Guo Jian Hu, and Xu Li. "Stress Corrosion Cracking of SPV50Q Steel in H2S-Containing Sour Environment." Advanced Materials Research 314-316 (August 2011): 1087–91. http://dx.doi.org/10.4028/www.scientific.net/amr.314-316.1087.
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It has a great tendency to the problem of environmental cracking under the service condition of LPG containing wet H2S surpassing the lowest allowance for steels. In order to quantitatively evaluate the cracking susceptibility on this steel in the wet H2S environment, the pre-fatigue crack M-WOL specimen stress corrosion cracking tests in three H2S concentrations were performed under the different welding conditions, and in safety performance analysis of equipment, and preventing countermeasure had been proposed. The results show that the presence of H2S considerably influences the corrosion process of SPV50Q steel and its corrosion rate increases with increasing H2S contents. With decreasing pH and increasing in temperature of the testing solution, the corrosion of this steel is also enhanced. Although the semicircular diameter of capacitive loop increases with immersion time, its variation amplitude is not obviously great and begins to diminish after certain periodic time, suggesting that the sulfide film formed on the surface can not effectively prevent SPV50Q steel for avoiding the further corrosion.
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Lin, Shu Xian, Yu Hui Huang, Fu Zhen Xuan, and Shan Tung Tu. "Study on Stress Corrosion Cracking Sensitivity of CrNiMoV Steam Turbine Rotor Steels." Key Engineering Materials 795 (March 2019): 102–8. http://dx.doi.org/10.4028/www.scientific.net/kem.795.102.
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The stress corrosion sensitivities of 25Cr2Ni2MoV, 26NiCrMoV10-10 and 30Cr2Ni4MoV low-pressure rotor steels in simulated nuclear steam turbine operation condition were investigated by slow strain rate test (SSRT), and the stress corrosion cracking (SCC) mechanisms were studied by optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Results revealed that the SCC sensitivity of 25Cr2Ni2MoV steel was highest in 3.5wt.%NaCl solution at 180°C, while the SCC sensitivity of 26NiCrMoV10-10 steel and 30Cr2Ni4MoV steel are similar. The SCC sensitivity of CrNiMoV steam turbine rotor steels could be decreased by the increase of Ni element and the decline of mechanical intensity. Cracks initiate from metal surface and then propagate to the inner metal, which showed a form of transgranular cracking.
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Rao, Si Xian, Su Ping Yang, Ji Bin Tong, and Jing Ru Wang. "Cracking Behavior of Oxide Films under Applied Stress." Advanced Materials Research 284-286 (July 2011): 671–75. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.671.
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Cracking behaviors of oxide films on A3, 30CrMnSiA steel under applied stress were investigated in this paper. Theoretical deductions confirmed that critical cracking conditions for oxide films on A3 and 30CrMnSiA steel did exist. Electrochemical tensile experiments in 3%NaCl aqueous solution showed that the critical cracking stress for oxide film on A3 steel is about 220MPa,the critical cracking stress for oxide film on 30CrMnSiA steel is about 80MPa.In-situ dynamic tensile experiments verified the correctness of the experiments results in the electrochemical tensile experiments.
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Truschner, Mathias, Jacqueline Deutsch, Gregor Mori, and Andreas Keplinger. "Cathodic and Anodic Stress Corrosion Cracking of a New High-Strength CrNiMnMoN Austenitic Stainless Steel." Metals 10, no. 11 (November 19, 2020): 1541. http://dx.doi.org/10.3390/met10111541.
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A new high-nitrogen austenitic stainless steel with excellent mechanical properties was tested for its resistance to stress corrosion cracking. The new conventional produced hybrid CrNiMnMoN stainless steel combines the excellent mechanical properties of CrMnN stainless steels with the good corrosion properties of CrNiMo stainless steels. Possible applications of such a high-strength material are wires in maritime environments. In principle, the material can come into direct contact with high chloride solutions as well as low pH containing media. The resistance against chloride-induced stress corrosion cracking was determined by slow strain rate tests and constant load tests in different chloride-containing solutions at elevated temperatures. Resistance to hydrogen-induced stress corrosion cracking was investigated by precharging and ongoing in-situ hydrogen charging in both slow strain rate test and constant load test. The hydrogen charging was carried out by cathodic charging in 3.5 wt.% NaCl solution with addition of 1 g/L thiourea as corrosion inhibitor and recombination inhibitor to ensure hydrogen absorption with negligible corrosive attack. Slow strain rate tests only lead to hydrogen induced stress corrosion cracking by in-situ charging, which leads to total hydrogen contents of more than 10 wt.-ppm and not by precharging alone. Excellent resistance to chloride-induced stress corrosion cracking in 43 wt.% CaCl2 at 120 °C and in 5 wt.% NaCl buffered pH 3.5 solution at 80 °C is obtained for the investigated austenitic stainless steel.
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Yao, Xiao Fei, Fa Qin Xie, Xiang Qing Wu, and Yi Fei Wang. "Effects of pH Value on the Stress Corrosion Cracking of Super 13Cr Tubing Steel." Advanced Materials Research 557-559 (July 2012): 127–30. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.127.
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Effects of pH value on the stress corrosion cracking (SCC) of super 13Cr tubing steel were investigated in 3.5% NaCl solution, that mechanics properties and fracture morphology and SCC resistance and stress corrosion cracking susceptibility index (kscc) were analyzed by slow strain rate tensile (SSRT) stress corrosion cracking experiment method and σ-ε curve and SEM. the results Effects of pH value on the stress corrosion cracking (SCC) of super 13Cr tubing steel were investigated in 3.5% NaCl solution, that mechanics properties and fracture morphology and SCC resistance and stress corrosion cracking susceptibility index (kscc) were analyzed by slow strain rate tensile (SSRT) stress corrosion cracking experiment method and σ-ε curve and SEM. the results showed that super 13Cr tubing steel has good properties of resistance stress corrosion cracking in acidic medium, effects of pH value on super13Cr tubing steel resistance stress corrosion was not very obviously in the acidic medium, with pH value decreased, super 13Cr tubing steel tensile strength decreased, elongation rate decreased, fracture area contraction ratio decreased, break time reduced, the tendency of the stress corrosion cracking increased. the stress corrosion cracking susceptibility index kσ and kε were all increasing, that increased degree of kε were obviously than kσ, effects of pH value on the plastic deformation of super 13Cr tubing steel were greater than tensile strength.
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Tomków, J., D. Fydrych, G. Rogalski, and J. Łabanowski. "Temper Bead Welding of S460N Steel in Wet Welding Conditions." Advances in Materials Science 18, no. 3 (September 1, 2018): 5–14. http://dx.doi.org/10.1515/adms-2017-0036.
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AbstractWet welding is the most common method of welding in water environment. It is most often used for repairing of underwater parts of offshore structures. However, the water as a welding environment causes an increase of susceptibility of steels to cold cracking. For underwater constructions high strength low alloy (HSLA) steel are widely used. In wet welding condition a HSLA steel is characterized by high susceptibility to cold cracking. Temper Bead Welding (TBW) was chosen as a method to improve the weldability of S460N steel. The studies showed that TBW technique causes significant decrease of maximum hardness of heat affected zone (HAZ). The largest decrease in hardness occurred in specimens with the pitches in range 66-100%.
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Jonsta, Petr, Zdenek Jonsta, Irena Vlckova, and Jaroslav Sojka. "Influence of Physical-Metallurgical Factors on Resistance of API Carbon Steels to Sulphide Stress Cracking." Communications - Scientific letters of the University of Zilina 20, no. 4 (December 31, 2018): 41–46. http://dx.doi.org/10.26552/com.c.2018.4.41-46.
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The paper deals with the influence of physical-metallurgical factors on resistance of the X52 and X70 steels in accordance with API 5L to sulphide stress cracking. The resistance against this kind of damage is relatively clearly claimed by usually used approach in this field by the tensile strength of steel, its hardness level, respectively. However, the experimental results had shown that the microstructural parameters are also the significant factors, which affect the resistance of steels to sulphide stress cracking. It was found that the quenching and tempering can significantly increase the resistance to sulphide cracking as in the case of hydrogen induced cracking. It would be appropriate to re-evaluate the material selection process that recommends to use the steels not exceeding approved strength limit in a case of the sulfane environments where the risk of the sulphide stress cracking exists.
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Serna, Sergio, Julio C. Villalobos, Osvaldo Flores, Horacio Martínez, Edgar López, and Bernardo Campillo. "Efecto del H2S en la Susceptibilidad al Agrietamiento de Dos Aceros Microaleados para Tubería." KnE Engineering 3, no. 1 (February 11, 2018): 424. http://dx.doi.org/10.18502/keg.v3i1.1447.
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Cracking in sour media modes were observed, and these were related mainly to the microstructure produced during the thermomechanical process of two microalloyed steels grade API X 52. Through the use of linear elastic fracture mechanics modified specimens. Steels loaded at similar initial stress intensity factors showed different cracking modes that were related directly to their different microstructures. Steels microstructures indicate different fabrication routes. Testing temperature played an important role on switching the cracking characteristics being remarkable by the ferrite-pearlite steel microstructure. A banded microstructure is susceptible to the effects of hydrogen at room T. While, an acicular ferrite microstructure with carbides patches at grain boundaries is susceptible to anodic dissolution in front of the crack tip, no matter the temperature being tested. Key words: microalloyed steels, sour service, cracking modes, microstructure.
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Cao, Fu Bo, Hong Gang Wei, and Zhi Hui Cheng. "The Experimental Study on Steel Crane-Girder before and after Reinforcement." Applied Mechanics and Materials 351-352 (August 2013): 1364–67. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.1364.
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This article focuses on a cracking steel crane girder of one factory, on the basis of extensive investigation and research on the fatigue damage of cracking steel crane girder at home and abroad. Sectional stress is redistribution and the stress concentration phenomenon of the crack tip has been alleviated. After reinforcement, the local stiffness of the upper flange and web greatly increases, The results show that it can extend the fatigue remaining service life of fatigue cracking of the steel crane girder by increasing the effective cross section area and stiffness, and it is a good guide on reinforcement and maintenance of actual industrial plant cracking steel crane girder.
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Sergeev, N. N., V. V. Izvol'skiy, A. N. Sergeev, S. N. Kutepov, A. E. Gvozdev, E. V. Ageev, and D. S. Klement'yev. "THE INFLUENCE OF MICROSTRUCTURAL FACTORS AND HEAT TREATMENT ON THE CORROSION RESISTANCE OF REINFORCING STEEL CLASS A 600." Proceedings of the Southwest State University 22, no. 2 (April 28, 2018): 52–63. http://dx.doi.org/10.21869/2223-1560-2018-22-2-52-63.
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Currently, hot rolled bar reinforcement class A600 of low-alloy steels in the delivery condition has a high tendency to this very specific kind of destruction as stress corrosion cracking under tension (SCC). However, there are cases of collapse of pre-stressed concrete structures, in most cases initiated corrosion cracking under stress, put the problem this type of fracture is particularly acute. In stress corrosion cracking cracks occur, the occurrence of which depends not only on the structural state of the material, the type and level of stress, but also on the degree of aggressiveness of the environment in which the operation occurs. In this regard, it is very important to establish how the corrosion resistance of class A600 reinforcing steel varies depending on the change in the chemical composition, microstructure, the level of applied and residual micro-stresses, and various modes of heat treatment. The purpose of this paper is to study the effect of the above factors on the resistance of low-alloyed reinforcing steel class A600 stress corrosion cracking It is shown that the sensitivity of the reinforcement to stress corrosion cracking is largely determined by the chemical composition (mainly carbon content), the type of microstructure and the level of residual micro-stresses. The influence of heat treatment regimes on the corrosion resistance of A600-grade reinforcing steel in nitrates solutions is investigated. It is shown that the use of additional heat treatment (normalization and improvement) increases the corrosion resistance of steel. High corrosion resistance steel reinforcement has only a carbon content at the lower limit of the vintage composition, which is provided by the structure of homogeneous bainite with mechanical properties at the level of strength class A600. With higher mechanical properties, the steel reinforcement has lower corrosion resistance.
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Chaudhri, M. M. "Compression cracking of steel ball bearings." Philosophical Magazine A 71, no. 5 (May 1995): 1069–82. http://dx.doi.org/10.1080/01418619508236237.
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Agarwal, Gautam, He Gao, Murugaiyan Amirthalingam, and Marcel Hermans. "Study of Solidification Cracking Susceptibility during Laser Welding in an Advanced High Strength Automotive Steel." Metals 8, no. 9 (August 28, 2018): 673. http://dx.doi.org/10.3390/met8090673.
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Susceptibility to weld solidification cracking in transformation-induced plasticity steel sheets was studied using a modified standard hot cracking test used in the automotive industry. To vary the amount of self-restraint, bead-on-plate laser welding was carried out on a single-sided clamped specimen at increasing distances from the free edge. Solidification cracking was observed when welding was carried out close to the free edge. With increasing amount of restraint, the crack length showed a decreasing trend, and at a certain distance, no cracking was observed. With the aid of a finite element-based model, dynamic thermal and mechanical conditions that prevail along the transverse direction of the mushy zone are used to explain the cracking susceptibility obtained experimentally. The results indicate that the transverse strain close to the fusion boundary can be used as a criterion to predict the cracking behavior. The outcome of the study shows that optimum processing parameters can be used to weld steels closer to the free edge without solidification cracking.
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Zhang, Shi Ping, and Xiang Dong. "Effect of Steel Fiber on the Performance of Concrete Materials." Applied Mechanics and Materials 193-194 (August 2012): 337–40. http://dx.doi.org/10.4028/www.scientific.net/amm.193-194.337.
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This paper presents the results of testing performed to evaluate the influence of steel fiber on the performance of concrete materials. The performance of concrete materials was studied through frost resistance, carbonation testing and restraint cracking testing. Experimental results show that the steel fibers can improve the frost resistance and carbonation of concrete, compared with plain concrete. Steel fibers can also reduce cracking, and improve the cracking resistance of concrete materials.
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Bashir, Alyona, Włodzimierz Dudziński, Marek Dudziński, and Teresa Ptak. "Corrosion Fatigue Crack Propagation Rates for Steam Turbine Blade 13% Cr Steels." Solid State Phenomena 227 (January 2015): 7–10. http://dx.doi.org/10.4028/www.scientific.net/ssp.227.7.
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Studies of stress corrosion in X12Cr13 and X20Cr13 steels used for rotor blades of steam turbines have been conducted for determining the average rate of corrosion cracking development da / dt. Specimens were exposed to the salt mist environment of 1,2 ppm NaCl concentration in temperature of 60° C. The research environment represents the initial condensate of humidity from 3÷4%. Average rate of corrosion cracking development for specimens of the X12Cr13 is by 0,005 µm/h higher from specimens of the X20Cr13 steel. Course of the corrosion cracking initiation depends to a high degree on metal structure, and probably the close value of cracking propagation rate depends on the similar structure of those steels – high-tempered martensite with carbides at grain boundaries.
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Guo, Shengshan, Hui Liang, Yunrui Deng, Nan Wu, Deyu Li, Houqun Chen, and Aijing Zhang. "The Effect of Steel Reinforcement on Seismic Damage to Concrete Gravity Dams Based on Distributed-Steel Model." Journal of Earthquake and Tsunami 14, no. 02 (December 20, 2019): 2050010. http://dx.doi.org/10.1142/s1793431120500104.
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Tensile cracking at the position where geometry changes is a typical failure mode of gravity dams under strong earthquakes. Steel reinforcement has been proposed to reduce the degree of dam cracking. In this paper, a nonlinear model is presented to consider the interaction effect between the steel reinforcement and the dam concrete in a combined concrete damage model and distributed-steel model. In the model, a composite constitutive model of a steel reinforcement-concrete element is proposed. The approach can model the process of gradual degradation of the concrete loading capacity and load transfer to the steel reinforcement by establishing the concrete and steel models separately. Taking a typical gravity dam with positions where geometry changes upstream and downstream as a case study, the influence of steel reinforcement on seismic damage of the gravity dam is investigated. The analytical results show that the steel reinforcement strengthening prevents cracks thoroughly around the elevation of the downstream slope change. However, the cracking around the elevation of the upstream slope change extends to the downstream direction. This reflects the transfer of fracture energy release during the cracking process.
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Mohrbacher, Hardy. "Martensitic Automotive Steel Sheet - Fundamentals and Metallurgical Optimization Strategies." Advanced Materials Research 1063 (December 2014): 130–42. http://dx.doi.org/10.4028/www.scientific.net/amr.1063.130.
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Martensitic sheet steel is increasingly being used in advanced car body construction, especially in areas where high crash loads are expected. Using such steels appropriately the weight of individual components can be reduced by up to 20 percent. Martensitic steel sheet is commercially available in the strength range of 1200 to 1900 MPa, either as cold forming or hot stamping grade. Whereas the strength of such martensitic steels is practically only a function of the carbon content, other properties such as ductility, toughness, bendability and delayed cracking resistance are severely influenced by other alloying elements and the particular thermal processing route. The paper discusses the influence of various key-alloying elements such as Nb, Mo and B on these properties and suggests routes to optimize the steel’s behavior with respect to the manufacturing and application related aspects.Keywords Martensite, prior austenite grain size, delayed cracking, grain boundary segregation, hydrogen trapping, niobium, molybdenum
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Wang, Chuan, Li Li Sui, Qing Duo Hao, and Qi Yu Lu. "Experimental Research on the Cracking Behavior of GFRP/Steel Wire Composite Rebar Reinforced Concrete Beam Based on Cracking Mechanics." Applied Mechanics and Materials 252 (December 2012): 17–22. http://dx.doi.org/10.4028/www.scientific.net/amm.252.17.
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The different mechanical property determines the difference on cracking behavior between GFRP/steel wire composite rebar reinforced concrete beams and steel rebar reinforced concrete beams according to cracking mechanics. In order to study the cracking behavior of concrete beams reinforced with GFRP/ steel wire composite rebar, five simply-supported beams were tested under three-point static load. The test variables were beam section size and concrete cover depth. Based on analysis on the test results, the calculation methods of cracking capacity and maximum crack width were proposed, and the limit value of crack width was suggested.
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Troiano, E., A. P. Parker, and J. H. Underwood. "Mechanisms and Modeling Comparing HB7 and A723 High Strength Pressure Vessel Steels." Journal of Pressure Vessel Technology 126, no. 4 (November 1, 2004): 473–77. http://dx.doi.org/10.1115/1.1811108.
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HB7, an ultra-clean, high strength pressure vessel steel manufactured in France, is compared to A723 steel. This steel, suggested as an improved pressure vessel material is currently being proposed for critical applications, and will likely be used more frequently as design engineers discover its capabilities. This paper includes comparisons of strength, fracture toughness, fatigue properties and composition of the two steels, followed by an in-depth comparison and modeling of environmental cracking resistance, Bauschinger-modified residual stresses and fatigue lives. Results indicate that in all critical areas, with the exception of Bauschinger-reduced residual stress, the HB7 is superior to the A723 steel. Particularly for small amounts of autofrettage, near-bore residual stresses are reduced for HB7 steel compared to those for A723 steel at the same strength level. The greatest improvement of the HB7 over the A723 is in environmental cracking resistance. The HB7, when tested in concentrated sulfuric acid, exhibits five orders of magnitude longer crack incubation times and three orders of magnitude slower crack growth rates, when compared to A723 steel at the same strength level.
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Persaud, S. Y., K. Arioka, K. Farquharson, C. Dixon, and C. D. Judge. "A Mechanistic Study of Carbon Steel Cracking in 360°C Air and Hydrogen Environments." CORROSION 75, no. 11 (September 24, 2019): 1354–70. http://dx.doi.org/10.5006/3294.
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Thirty percent cold-worked (CW) carbon steel tensile specimens were exposed to 360°C air and hydrogen environments (2 MPa H2 and 20 MPa H2) under an applied load to produce intergranular creep cracking. In this study, cutting-edge microscopy techniques were applied to characterize cracking on multiple length scales and in three dimensions. The objective was to develop a better mechanistic understanding of creep cracking in carbon steel, and the known deleterious effect of hydrogen (attack) at the micro-to-nanoscale. Amorphous carbon along the fracture path was observed in all experiments, with evidence for nanoscale cavities/methane bubbles in hydrogen exposures, particularly at cementite-ferrite boundaries. Results suggested that creep or residual stress led to breakdown of cementite to amorphous carbon, cavitation, and/or formation of methane (depending on H2 content); it is suggested that the combination of deleterious mechanisms leads to initiation and/or acceleration of creep cracking in CW carbon steel. Comparisons are made between the morphology of creep cracking in these laboratory experiments and recent results from characterization of creep cracking in ex-service carbon steel piping from a CANDU nuclear power plant. Although more subtle, similar morphology and chemistry at crack tips in laboratory and ex-service CW carbon steel suggests that the mechanism(s) of creep cracking is similar.
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Haddad, Rami H., and Ahmed M. Ashteyate. "Role of synthetic fibers in delaying steel corrosion cracks and improving bond with concrete." Canadian Journal of Civil Engineering 28, no. 5 (October 1, 2001): 787–93. http://dx.doi.org/10.1139/l01-037.
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An experimental study was conducted to investigate the bond behavior between corroding reinforcing steel and surrounding synthetic fiber reinforced concrete. Pullout concrete and fiber reinforced concrete specimens were prepared at concrete cover to steel bar diameter ratios of 3.1 and 3.7 with three embedded lengths of 100, 200, and 300 mm. Fiber reinforced concrete was prepared using polypropylene at 0.15% and 0.30% or nylon fibers at 0.3% by mix volume. After moist curing for 90 days, pullout specimens, originally contaminated by up to 11 kg/m3 NaCl, were subjected to a special treatment to accelerate corrosion in steel. The bond stressslippage relationship was evaluated at different corrosion levels. The findings indicated that the use of fibers delayed initiation of cracking, due to steel corrosion, and improved the ultimate bond strength at cracking and post-cracking stages. The percentage improvement in ultimate bond strength at the latter stages reached as high as 52% and 87%, respectively. It was noticed that, prior to cracking, corrosion of steel bars resulted in an increase in bond strength, regardless of the concrete cover to bar diameter ratio used, or whether fibers were used or not. After cracking (due to steel corrosion), pullout specimens prepared with polypropylene fibers showed better resistance than that of corresponding ones with nylon fibers.Key words: fibers, reinforced concrete, corrosion, cracking, bond strength, slippage.
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Hansson, Per, and Magnus Areskoug. "Possibilities with Use of Electron Beam Welding of Very High Strength Steel." Materials Science Forum 941 (December 2018): 443–52. http://dx.doi.org/10.4028/www.scientific.net/msf.941.443.
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Welding of very high strength quenched and tempered steel, Rp0.2≥ 900 MPa, put high demands on choice of welding process, consumables and also on the heat input. Such steels commonly have a quite narrow tolerance box for a suitable weld heat input to control the cooling time, Δt8/5, pertaining to minimize the risk for generating weld defects such as undercut, a too soft weld heat affected zone, delayed cracking etc. When welding very high strength steel is the risk for cold cracking in the weld metal not negligible due to the high alloy content of such high strength filler wires used. Furthermore, filler metal wires having equal strength levels to very high strength steel are hard to find which, together with the above described drawbacks, favour use of under-matching filler wires.
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Cao, Luo Wei, Chen Yang Du, and Guo Shan Xie. "Effects of Sensitization and Hydrogen on Stress Corrosion Cracking of 18-8 Type Stainless Steel." Applied Mechanics and Materials 853 (September 2016): 168–72. http://dx.doi.org/10.4028/www.scientific.net/amm.853.168.
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Austenitic stainless steels always failure in intergranular corrosion, stress corrosion cracking and their synthesis. Moreover, hydrogen also plays an important role in SCC. Effects of sensitization and hydrogen on stress corrosion cracking of 18-8 type stainless steel (304 and 304L) were investigated in this paper. Three states of specimens, including as-received, sensitization and hydrogen precharged, were prepared for this study. Two kinds of environment, involving air and 0.5mol H2SO4 +0.01mol KSCN solution, were selected to compare the SCC sensitivity of different condition of 304 and 304L by the slow strain rate tensile test (SSRT). Fracture morphology was observed by scanning electron microscope (SEM) to check the SCC fracture characteristic. In SEM, evident secondary cracks were found on the fracture surface of 304. Results showed that: 1) hydrogen precharged 304L has high SCC sensitivity (85.7% ) compared with low SCC sensitivity in solution (14.5%), which reveal that SCC of 304L is hydrogen-induced cracking type; 2) 304 stainless steel has high SCC sensitivity (60.8%); 3) sensitization increases the SCC sensitivity of 304 stainless steel (from 60.8% to 71.4%).
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Fydrych, D., J. Łabanowski, J. Tomków, and G. Rogalski. "Cold Cracking Of Underwater Wet Welded S355G10+N High Strength Steel." Advances in Materials Science 15, no. 3 (September 1, 2015): 48–56. http://dx.doi.org/10.1515/adms-2015-0015.
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Abstract Water as the welding environment determines some essential problems influencing steel weldability. Underwater welding of high strength steel joints causes increase susceptibility to cold cracking, which is an effect of much faster heat transfer from the weld area and presence of diffusible hydrogen causing increased metal fragility. The paper evaluates the susceptibility to cold cracking of the high strength S355G10+N steel used, among others, for ocean engineering and hydrotechnical structures, which require underwater welding. It has been found from the CTS test results that the investigated steel is susceptible to cold cracking in the wet welding process.
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Zhao, Xuehui, Wei Huang, Guoping Li, Yaorong Feng, and Jianxun Zhang. "Effect of CO2/H2S and Applied Stress on Corrosion Behavior of 15Cr Tubing in Oil Field Environment." Metals 10, no. 3 (March 23, 2020): 409. http://dx.doi.org/10.3390/met10030409.
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The corrosion behavior of a 15Cr-6Ni-2Mo martensitic stainless steel (15Cr stainless steel) in a CO2/H2S environment was investigated by conducting high-temperature/high-pressure immersion tests combined with scanning electron microscopy and metallographic microscopy. The presence of H2S decreased the corrosion resistance of the 15Cr tubing steel. The critical H2S partial pressure (PH2S) for stress corrosion cracking in the 15Cr tubing steel in the simulated oil field environment with a CO2 partial pressure of 4 MPa and an applied stress of 80% σs was identified. The 15Cr tubing steel mainly suffered uniform corrosion with no pitting and cracking when the PH2S was below 0.5 MPa. When the PH2S increased to 1 MPa and the test temperature was 150 °C, the pitting and cracking sensitivity increased. The stress corrosion cracking at a higher PH2S is attributed to the sulfide-induced brittle fracture.
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Tang, Zheng Lian, and Xin Ping Zhang. "Effect of Rare Earth on 30CrMnSi Steel Investment Castings Cracking." Advanced Materials Research 160-162 (November 2010): 692–97. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.692.
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Through adding different amounts of rare earth into the crack sensitive 30CrMnSi steel samples used in investment casting, the cracking tendency of the steel was evaluated and the optimum amount of rare earth addition was obtained. The results show that the cracking susceptibility decreases with the increase of the amount of rare earth added. The cracking susceptibility was lowest at the addition amount of rare earth ferrosilicon alloy being 450g per 50kg of 30CrMnSi steel, while increasing again thereafter with the addition amount up to 600g. It was revealed that the addition of rare earth with an appropriate amount can refine grains, reduce sulfur content, change the volume fraction and size of inclusions as well as improve their distribution, reduce or eliminate ferrite network in castings, and improve the hardness of the matrix, thus finally reduce the cracking susceptibility of the steel.
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Feng, Chai, Cai Fu Yang, Su Hang, Yong Quan Zhang, and Xu Zhou. "Cracking Resistance of Cu-Bearing Age-Hardening Steel." Key Engineering Materials 353-358 (September 2007): 2015–20. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.2015.
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In this paper, the weldablity of a low-carbon Cu-bearing age-hardening steel was evaluated using Y-groove cracking evaluation test. The results show that the steel has a low hardenability characteristic and cold-cracking susceptibility. It is also indicated that a crack-free weldment can be obtained during welding of this type of steel even at an ambient temperature as low as -5°C as well as in an absolute humidity lower than 4000Pa without any preheat treatment. A slight preheat treatment can prevent the joint from cracking when welding is carried out at lower ambient temperature or in higher absolute humidity.
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Yoo, Y. R., H. Y. Chang, Yong Bum Park, Y. S. Park, Tai Joo Chung, and Young Sik Kim. "Influence of Thermal Treatment on the Caustic SCC of Super Austenitic Stainless Steel." Materials Science Forum 475-479 (January 2005): 4227–30. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.4227.
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In general, thermal treatment at 500oC ~ 900oC ranges depending upon alloy composition of stainless steels can sensitize the steels and promote the intergranular cracking, and their intergranular corrosion resistance is decreased. These behaviors seem to be related to the change of microstructures. So, heat treatment at that temperature range should be avoided in fabrication, especially welding of stainless steels. In this work, it is focused on the effect of thermal treatment on caustic stress corrosion cracking of super austenitic stainless steel - S32050 The low temperature thermal treatment increased greatly the resistance to caustic SCC than those of annealed specimen. This enhancement might be closely related to the reduction of residual stress and slightly large grain, but its resistance was not affected by the anodic polarization behavior.
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Gabelchenko, N. I., E. Y. Karpova, A. I. Gabelchenko, and A. P. Ryshko. "RESEARCH OF THE METAL WORKING IN THE ENVIRONMENTS CAUSING SODIUM HYDROGEN CRACKING." IZVESTIA VOLGOGRAD STATE TECHNICAL UNIVERSITY, no. 7(242) (July 29, 2020): 28–33. http://dx.doi.org/10.35211/1990-5297-2020-7-242-28-33.
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The results of a study of a metal working in environments causing hydrogen sulfide cracking are presented. The previously studied steels were induced in a hydrogen sulfide-containing medium under the action of tensile stresses in the metal of the samples. It has been established that characteristic defects in the form of bubbles and blisters are formed on the surface of metals. A study of microstructures showed that cracks originate at the boundary between pearlite and ferrite grains and on the streaked sulfide phase of the FeS · MnS type. Disclosure of the boundary of pearlitic and ferrite grains is due to their surface contamination with microimpurities. The results of the analysis for inclusions show that 20YuCH steel is much cleaner in inclusions than American steel of the type steel 20, and sulfides are more dispersed and coagulated, while a significant part of the sulfur is bound by cerium. This explains the best resistance of steel 20YUCH against hydrogen sulfide cracking.
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Kytinou, Violetta K., Constantin E. Chalioris, and Chris G. Karayannis. "Analysis of Residual Flexural Stiffness of Steel Fiber-Reinforced Concrete Beams with Steel Reinforcement." Materials 13, no. 12 (June 13, 2020): 2698. http://dx.doi.org/10.3390/ma13122698.
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This paper investigates the ability of steel fibers to enhance the short-term behavior and flexural performance of realistic steel fiber-reinforced concrete (SFRC) structural members with steel reinforcing bars and stirrups using nonlinear 3D finite element (FE) analysis. Test results of 17 large-scale beam specimens tested under monotonic flexural four-point loading from the literature are used as an experimental database to validate the developed nonlinear 3D FE analysis and to study the contributions of steel fibers on the initial stiffness, strength, deformation capacity, cracking behavior, and residual stress. The examined SFRC beams include various ratios of longitudinal reinforcement (0.3%, 0.6%, and 1.0%) and steel fiber volume fractions (from 0.3% to 1.5%). The proposed FE analysis employs the nonlinearities of the materials with new and established constitutive relationships for the SFRC under compression and tension based on experimental data. Especially for the tensional response of SFRC, an efficient smeared crack approach is proposed that utilizes the fracture properties of the material utilizing special stress versus crack width relations with tension softening for the post-cracking SFRC tensile response instead of stress–strain laws. The post-cracking tensile behavior of the SFRC near the reinforcing bars is modeled by a tension stiffening model that considers the SFRC fracture properties, the steel fiber interaction in cracked concrete, and the bond behavior of steel bars. The model validation is carried out comparing the computed key overall and local responses and responses measured in the tests. Extensive comparisons between numerical and experimental results reveal that a reliable and computationally-efficient model captures well the key aspects of the response, such as the SFRC tension softening, the tension stiffening effect, the bending moment–curvature envelope, and the favorable contribution of the steel fibers on the residual response. The results of this study reveal the favorable influence of steel fibers on the flexural behavior, the cracking performance, and the post-cracking residual stress.
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Stopyra, Michał, and Janusz Adamiec. "Cracking of 7CrMoVTiB10-10 (T24) Steel Weld Joints." Solid State Phenomena 226 (January 2015): 87–90. http://dx.doi.org/10.4028/www.scientific.net/ssp.226.87.
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7CrMoVTiB10-10 (T24) steel was designed for high temperature applications, especially for water wall panels in modern supercritical coal-fired boilers. However, welding of T24 steel caused many problems due to its cracking susceptibility. In the present paper the causes of T24 steel weld joints cracking have been discussed. Microstructural and fractographic analysis of weld joint were conducted and hardness was measured. It was found that the main causes of crack’s formation in weld metal are hot cracking susceptibility of T24, high deformation during welding process and weld metals’ hardenability. The mechanism of cracking was determined. It was concluded that cracks had been initiated in high temperature brittleness range, then propagated through the weld metal in transverse direction as the cold cracks. The reduction of weld metal’s ductility was due to too high cooling rate and excessive hardening of weld metal in relation to base metal.
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Dey, Swapna, Seetharaman Sivaprasad, Nityananda Das, and Indranil Chattoraj. "Study of Electrochemical Behavior, Hydrogen Permeation and Diffusion in Pipeline Steel." Materials Science Forum 1019 (January 2021): 145–56. http://dx.doi.org/10.4028/www.scientific.net/msf.1019.145.
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The pipeline steels which are used for transportation of natural gas and crude oil suffer from hydrogen damage at their internal as well as external surfaces. The internal surfaces of pipelines are generally affected due to hydrogen induced cracking and the external surfaces due to the soil environmental conditions which cause stress corrosion cracking. In the present investigation, the electrochemical corrosion behavior of X70 pipeline steel was studied in sour environment and near neutral soil environment. To assess the mechanism of hydrogen damage in steel, electrochemical hydrogen charging and permeation techniques were used to characterize the hydrogen distribution, trapping and its diffusion in X70 pipeline steel. It has been found that corrosion behavior of pipeline steel in the sour environment is higher than the near neutral soil solution. From the hydrogen permeation study it is established that the hydrogen permeation rate increases with the square root of the charging current density, and the increase of hydrogen flux is directly proportional to the subsurface hydrogen concentration.
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Franklin, M. J., S. W. Huang, Tara Chandra, and A. Kiet Tieu. "Microstructural Features of Plasma Nitrided Molybdenum Alloy Steel." Materials Science Forum 539-543 (March 2007): 1282–87. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.1282.
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This research is part of a larger project to investigate the wear and friction of the centre bearing of a rail freight truck. Existing centre bearing surfaces include flame hardened AISI 1030 steel and AISI 1053 cast steel top centres mating against un-greased and/or greased Hadfield steel centre bowl liners, and polyethylene centre bowl liners. The wear life of the unlubricated steels against Hadfield steel is short, greasing the bearings is costly, and industry reports some failures of polyethylene centre bowl liners due to excessive plastic flow and cracking of the rim wall.
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Li, Zhuang, Di Wu, and Jian Xun Liu. "Analysis of Cracking Phenomenon Occurring during Cold Forging of ML25Mn Steel." Key Engineering Materials 324-325 (November 2006): 643–46. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.643.
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Cold forging has various advantages compared to other forming processing. Cracking phenomenon was taken place during cold forging of ML25Mn steel. In this study, microstructural analyses were made on the cracked regions of the steel. The reason of cracking phenomenon occurring during cold forging for ML25Mn steel was investigated based on SEM observation in detail. The results have shown that ML25Mn steel presents lower strength and toughness. A larger amount of inclusions which are composed of MnS and complex oxides containing Mg, Al, Mn, Fe, S, Ca and O are found, and the complex inclusion might be brought during the deoxidation and the solidification in smelting and casting. Non-metallic inclusions result in significant stress concentration, which cause cracking phenomenon occurring during cold forging of ML25Mn steel.
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Niu, Jian Gang, Bin Wu, and Jian Bao. "Experimental Study on the Flexural Impact Properties of Fiber Reinforced Lightweight Aggregate Concrete." Applied Mechanics and Materials 488-489 (January 2014): 696–99. http://dx.doi.org/10.4028/www.scientific.net/amm.488-489.696.
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Through experimental study on the flexural impact properties of different dosage of plastic-steel fiber and steel fiber reinforced lightweight aggregate concrete, the results show that energy dissipation of cracking and damaging of steel fiber reinforced lightweight aggregate concrete increase with the increase of fiber ratio. However, energy dissipation of cracking and damaging of plastic-steel fiber concrete increases in early stage and decreases later with the increase of plastic-steel fibers. Enhancement effect of energy dissipation of damaging of plastic-steel fiber is higher than steel fibers.
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Jonsta, Petr, Irena Vlckova, Zdenek Jonsta, Vladimir Tomasek, and Tatana Fenclova. "Resistance of High-Strength Steels to Stress Corrosion Cracking Depending on External Environment pH Factor." Communications - Scientific letters of the University of Zilina 20, no. 3 (September 30, 2018): 19–23. http://dx.doi.org/10.26552/com.c.2018.3.19-23.
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The paper deals with the study of stress corrosion cracking of high-strength steels in an aqueous environment with a varying pH factor ranging from 5.5 to 12.0. Steels were studied after quenching and tempering, one of the steels was prone to temper embrittlement.
Single-edge notched pre-cracked specimens were used for the experiments. Changes in the pH factor at the crack tip were measured using an antimony electrode. The pH factor values at the crack tip dropped to 2.0. Steel prone to temper embrittlement showed significantly shorter incubation period and more accelerated development of corrosion process compared to the optimized heat treatment of the second steel. Proneness to intergranular fracture was observed close to the fatigue crack tip. The obtained results expand the existing knowledge about localized corrosion processes leading to the refinement of the stress corrosion cracking model when changing the pH factor on the crack tip.