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Artigos de revistas sobre o assunto "The finest steel"
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Rusanescu, Carmen Otilia, Marin Rusanescu, Florina Violeta Anghelina e Ileana Nicoleta Popescu. "Study Deformability Ecological Steel (41Cr4)". Materiale Plastice 55, n.º 3 (30 de setembro de 2018): 357–60. http://dx.doi.org/10.37358/mp.18.3.5029.
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In this paper is studied the hot plastic deformability (plasticity and resistance to deformation) for the low-alloyed steel of heat treatment for mechanical engineering in two ways: compression and tension. Groups of low alloy steels is very important in terms of quality and quantity, the products of these steels have developed internal and external market. The plasticity variation were plotted with the temperature and it was established that the plasticity of the steel increases in the range 700-12000C, then decreases as a result of the firing of the grain boundaries, for the bars obtained from ingot and continuous cast blown it was noticed that the plasticity values are very close. Deformation resistance decreases as the temperature increases. The finest granulation was obtained for a final plastic deformation temperature of 8000C and a minimum degree of deformation of 45%.
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Wang, Yong, Chengyi Zhu, Guangqiang Li, Yulong Liu e Yu Liu. "Influence of Nb Content on Precipitation, Grain Microstructure, Texture and Magnetic Properties of Grain-Oriented Silicon Steel". Materials 13, n.º 23 (7 de dezembro de 2020): 5581. http://dx.doi.org/10.3390/ma13235581.
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The effects of Nb content on precipitation, microstructure, texture and magnetic properties of primary recrystallized grain-oriented silicon steel were investigated by various methods. The results show that the precipitates in primary recrystallized sheets are mainly MnS, Nb(C,N), composite precipitates of MnS and AlN, and composite precipitates of Nb(C,N) and AlN. Adding niobium could refine the primary recrystallized microstructure. The steel with 0.009 wt% Nb possesses the finest and the most dispersed precipitates, which contributes to the finest primary recrystallized microstructure due to the strong pinning force. Adding niobium is beneficial to obtain large volume fraction favorable texture for grain-oriented silicon steel, and the effect of Nb addition is not obvious when the content is higher than 0.009 wt%. After final annealing, the steel with 0.009 wt% Nb shows the best magnetic properties, B800 = 1.872 T, P1.7/50 = 1.25 W/kg.
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Wang, Tie Bao, Chun Xiang Cui, Lin Fang e Shao Jing Bu. "Fracture Behavior and Microstructure of 60Si2MnA Spring Steels Modified by V-Nb Inoculants". Advanced Materials Research 415-417 (dezembro de 2011): 1085–89. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.1085.
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The microstructure of V-Nb inoculants after melt spinning was investigated by performing TEM examination and to the sample steels, the prior austenite grain sizes and fracture morphology were investigated by SEM observation. The results show that the V-Nb inoculants obtained is amorphous and the sample steel modified by V-Nb inoculants which make it possible to be a large amount of nucleation centers existing in the form of (V, Nb)C and achieve the effect of grain refinement in the solidification stages of liquid steel has been found to have the finest prior austenite grain sizes and the average prior austenite grain sizes of steel without addition of V and Nb(Steel A), steel microalloyed with V and Nb(Steel B) and steel modified by V-Nb inoculants(Steel C) are respectively 30μm, 20μm and 10μm. Tensile behavior of samples was studied under tempering at 400°C for 30 min after quenching, tensile results show that the fracture of steel modified by V-Nb inoculants appears dimples which represent ductile fracture. However the tensile fracture of V-Nb microalloyed steel is mixture of quasi-cleavages and dimples. Under tempering at 550°C for 30 min, Steel B and Steel C both show a fractograph with cleavage fracture.
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Rezaei, SRJ, CW Siyayisa, Z. Tang e J. Moema. "The influence of austenitization time and temperature on the austenite grain growth in high Ti-V HSLA steels". Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 40, n.º 1 (24 de janeiro de 2022): 142–49. http://dx.doi.org/10.36303/satnt.2021cosaami.28.
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Generally, in high titanium-containing high strength low alloy (HSLA) steels, the challenge is to ensure that an adequate amount of Ti dissolves during soaking for precipitate strengthening during cooling or hot working. Therefore, this work focused on the effect of soaking time and temperature on the austenite grain growth kinetics of HSLA steels, of the three alloys containing 0.1 %Ti, and 0 to 0.12 %V. The samples were austenitized at 1150 and 1280 °C for 1, 2 and 3 hrs and quenched in a 10% NaCl brine. Thereafter, the samples were tempered at 490 °C for 72 hrs in order to reveal the prior austenite grain boundaries. The grain size was analysed by the linear intercept method. The precipitation behaviour was predicted by Thermo-Calc software and confirmed by SEM-EDS. At 1150 °C austenitizing temperature, all three steel grades exhibited the Ti (C, N) (Type 1), (Mn-Ti) (C, S) (Type 2), MnS (Type 3 (Ti4C2S2) (Type 4) and TiC (Type 5) precipitates. After escalating the temperature to 1280 °C, only the TiC dissolved. Type 4 and 5 precipitates were the finest and possibly responsible for the grain size refinement. Consequently, alloy 1 with the highest S content of 140 ppm exhibited the finest grain size at both temperatures.
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Maubane, Dannis Rorisang Nkarapa, Charles Witness Siyasiya, Kevin Mark Banks e Waldo Edmund Stumpf. "Critical Strain for Complete Austenite Recrystallisation during Rough Rolling of C-Mn Steel and Nb-Ti-V Microalloyed Steel". Materials Science Forum 941 (dezembro de 2018): 46–51. http://dx.doi.org/10.4028/www.scientific.net/msf.941.46.
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The influence of roughing strain on the extent of austenite recrystallisation in plain carbon steel and Nb-Ti-V microalloyed steel was investigated. Reheating and roughing simulations were conducted on a deformation dilatometer using industrial heating, soaking times, strain and strain rates. The roughing schedules comprised of varying the pass strain magnitude within a typical roughing temperature range. The double stroke method was used to determine the austenite softening fraction. The austenite grain size, prior to and after rolling, was measured on quenched specimens. Grain refinement was achieved in both steels after all rolling schedules. An applied pass strain of 0.15 was sufficient to completely soften the austenite after the first pass and produced the finest recrystallised grain size. This was attributed to sufficient nucleation sites and driving force for recrystallisation compared to lower strains. Partial recrystallisation occurred after the first pass due to the relatively coarse initial grain size. The steel chemistry played an insignificant role in controlling the recrystallisation kinetics at high roughing temperatures. The through-thickness strain distribution calculated from FEM simulations showed that, for a given applied strain, a similar magnitude of deformation is achieved at the centre of a hot-rolled plate.
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Xu, Jing, e Yi Tao Yang. "Comprehensive Influence of Cr and Si on Hardness and Wear Resistance of Cold Roll Steel". Advanced Materials Research 476-478 (fevereiro de 2012): 334–39. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.334.
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To improve the service performance of Cr-series steel for cold roller, the combined effects of chromium and silicon on hardness and wear resistance of cold roll steel had been studied in this paper on the basis of MC5 cold roll steel. The results showed that, with increasing Si content the hardness tended to decrease when Cr content was about the same. The hardness was the highest and the wear resistance was the best when Cr content was about 6.7% and Si content about 0.6%. The reason for this found by microscopic analysis was that the carbide size was the finest and carbides were the most dispersively distributed. Meanwhile, the amount of carbides was also the largest.
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Li, An Ming, Xiang Jie Wang e Li Juan Huang. "The Austenite Inverse Phase Transformation Quenching in Zero Time Holding of 20MnV Steel". Materials Science Forum 575-578 (abril de 2008): 1177–83. http://dx.doi.org/10.4028/www.scientific.net/msf.575-578.1177.
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The effect of second quenching temperature in zero time holding on 20MnV steel's strength and hardness was studied by the orthogonal regressive principle. The microstructure and property of the steel after austenite inverse phase transformation quenching in zero time holding were analyzed. Experiment results showed that the fine lath martensite of 20MnV steel was obtained through austenite inverse phase transformation quenching in zero time holding at 830°C-930°C. Within the range of Experiment's temperature, the structure of this steel quenched at 830°C is the finest. The microstructure will become coarse and the strength and hardness will become lower if the temperature goes up. The property of this steel can be increased remarkably by austenite inverse phase transformation quenching in zero time holding at lower temperature.
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Li, Xin Cheng, Yu Ting Luo, Wei Xing Zhu, Xiao Li Wang e Yi Chen. "Effect of Finish Rolling Process on Improvement of Lamellar Tearing Resistance of High-Rise Building Steel". Advanced Materials Research 1049-1050 (outubro de 2014): 460–63. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.460.
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A process of finish rolling was researched to enhance lamellar tearing resistant of the high-rise building steel EH36. Experimental results indicate that gain size decreased with the decrease of finish temperature. When the finishing temperature on 840/810/780/750°C respectively, microstructure is finest with the size of 11.4μm. Moreover, the size of TiC precipitation turned ideal as the coiling temperature decreased. When coiling temperature is 550°C, the average size of TiC precipitation is only 0.09μm, refined by 40% relative to the conventional process. The microstructure and precipitation phase size of test steel are both effectively controlled because of the improved process. Therefore, high-rise building steel EH36 is finally prepared, and the lamellar tearing resistance reaches up to 78.2%.
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Maubane, Rorisang, Kevin Banks, Waldo Stumpf, Charles Siyasiya e Alison Tuling. "The Influence of Initial Grain Size and Strain Sequence of Slab Hot Rolling on the Austenite Evolution of Peritectic Microalloyed Plate Steels". Advanced Materials Research 1019 (outubro de 2014): 339–46. http://dx.doi.org/10.4028/www.scientific.net/amr.1019.339.
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The influence of the strain sequence during slab hot rolling (also known as “roughing”) on the evolution of austenite in plain carbon, C-Mn-V and C-Mn-Nb-Ti-V steels was investigated. Reheating and roughing simulations were conducted in a Bähr deformation dilatometer using a constant austenitising temperature, constant soaking time and various heating rates and roughing strain sequences. Stress analysis was used to quantify the austenite softening behaviour and the prior austenite grain size was measured from quenched specimens. The austenite grains of the plain carbon steel were coarser than those of both microalloyed steels, with the C-Mn-Nb-Ti-V grade being the finest due to effective pinning of the grain boundaries. Pass strains greater than 0.2 were sufficient for initiation of dynamic recrystallisation (DRX) for the C-Mn and C-Mn-V steels and led to uniform austenite microstructure with austenite grain sizes less than 40µm after the roughing stage.
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Mohammadjafar Hadad. "Some Experimental Aspects of Grinding Soft Steel Under Different Machining Conditions". Engineering Science & Technology 1, n.º 1 (30 de setembro de 2019): 8–16. http://dx.doi.org/10.37256/est.11202040.
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In this study, the effects of dressing parameters, wheel topography and machining environment on grinding performance of soft steel are investigated. To generate different grinding wheel topographies, dressing speed and depth have been changed during dressing of vitrified Al2O3 wheels using single point diamond dresser. After dressing of grinding wheels, machining tests have been conducted to study the influence of the wheel topography and coolant-lubricant types on the performance of grinding operation. The results suggest that MQL is more suited to grinding of soft material in the finishing step (shallow cut) with the finest dressing than wet and dry grinding.
Teses / dissertações sobre o assunto "The finest steel"
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Jesic, James John. "The utilisation of reclaimed asphalt and steel slag fines". Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403088.
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Thiele, Jeffery D. "An investigation of surface generation mechanisms for finish hard turning of AISI 52100 steel". Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17642.
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Dhulipalla, Ajay Krishna. "Effect of surface finish and hard coatings on scuffing of steel discs". Thesis, Cardiff University, 2006. http://orca.cf.ac.uk/56106/.
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The principal purpose of the work described in this thesis was to develop an insight into the scuffing performance of steel discs used to simulate gear tooth contacts under severe conditions of load, sliding and high temperature. Different surface conditions of the discs such as ground, superfinished, ground/hard-coated, and superfinished/ hard-coated were investigated in various combinations and at sliding speeds of up to 16 m/s in order to obtain an understanding of the possible beneficial effect of improved surface finish and the application of hard coatings on scuffing performance under the severe conditions experienced in an aerospace transmission such as a helicopter main rotor gearbox. The lubricant used in all tests was an oil commonly used in aerospace transmissions. It was found that the diamond-like coating (DLC) investigated in this work had the effect of markedly improving the scuffing resistance of the hardened steel substrate. In tests using the ground/coated samples, for example, it was not found possible to produce scuffing within the load and temperature limits of the test rig used (2.0 GPa maximum Hertzian contact pressure or 300 C maximum disc bulk temperature) even at the high sliding speed of 16 m/s. In addition to improving scuffing resistance it was found that the effect of the hard coating was to reduce friction and operating temperatures for a given load/speed combination. Superfinishing of the steel discs also led to a reduction in friction, but did not produce a significant improvement in scuffing resistance. It was found that the combination of ground/hard-coated discs running against ground/uncoated discs produced a remarkable behaviour of the discs' bulk temperatures, which suggests that the hard coating acts as a thermal barrier. Micro-elastohydrodynamic lubrication (micro-EHL) analyses were conducted using surface profiles of discs used in the experimental work. These theoretical simulations demonstrated the very severe lubrication conditions which are present in the experiments. Pressure ripples far in excess of the calculated Hertzian pressure are predicted, and the films generated by hydrodynamic action are extremely thin. Under the most severe conditions transitory direct "dry" contact is predicted.
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Al-Shahrani, Saeed. "Effect of surface finish on fatigue of austenitic stainless steels". Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/effect-of-surface-finish-on-fatigue-ofaustenitic-stainless-steels(6acdedf2-4211-433b-b37a-2846dc6138d2).html.
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The effect of surface finish on fatigue limit of two types of austenitic stainless steels (AISI 304L and AISI 316L) has been investigated. Fatigue specimens having two different surface conditions were obtained by changing the final cutting condition; annealing was performed to separate the residual stress effects from surface roughness. Electropolished samples were tested as a reference for each material. A generic mechanistic model for short fatigue crack propagation proposed by Navarroand Rios (N-R model) was implemented to assess its suitability for predicting the fatigue behaviour of specimens with various controlled surface conditions, obtained by machining. The surface/material properties required to implement this model were obtained by electron backscatter diffraction (EBSD), surface profilometry, hardness testing and X-ray diffraction residual stress measurement. The fatigue limits were determined using rotating-bending by means of the staircase method. The fatigue limits predicted by the N-R fatigue model were compared with the results of the fatigue tests. There was no agreement between the prediction and observations, indicating that the original form of the N-R model is not appropriate for austenitic stainless steels. In AISI 304L, the surface residual stresses are the dominant parameter, allowing prediction of the effects of machining on fatigue resistance while, the surface roughness developed by machining has no significant effect. In AISI 316L, the effect of surface roughness is found to be negligible, with a weaker effect of surface residual stress than has been observed for AISI 304L. Crack nuclei in run-out (>107 cycles) fatigue tests were observed to arrest at twins and martensite packets, developed by fatigue in AISI 316L and AISI 304L, respectively. Good agreement with experiments was achieved by using a modification to the fatigue model, which takes account of the observed effect of the plastic deformation on the microstructure.
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McKelvey, Sean Ambrose. "Influence of Surface Finish on Bending Fatigue of Forged Steel Including Heating Method, Hardness, and Shot Cleaning Effects". University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1302110057.
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Næss, Monika. "EFFECT OF MICROSTRUCTURE AND SURFACE FINISH ON LOCALIZED CORROSION PERFORMANCE OF SUPER DUPLEX STAINLESS STEEL IN SEAWATER". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for produksjons- og kvalitetsteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25741.
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Corrosion resistant alloys (CRAs) used in subsea pressure-retaining components must be compatible with production fluids and resistant to pitting and crevice corrosion in seawater. Whereas materials selection in production environments is governed by well-established international standards such as ISO 15156, much debate still exists as of how to determine the seawater localized corrosion resistance of higher grade CRAs such as duplex super duplex stainless steels (DSS and SDSS, respectively). While most industry specifications rely on the ASTM G48 standard to determine localized corrosion resistance, for duplex and super-duplex stainless steels there is no consensus on surface finish prior testing (e.g. polishing or pickling) and test temperature (e.g. 50 °C in NORSOK 630 versus 40 °C in ASTM A923). Moreover, it is unclear whether existing procedures are sensitive enough to determine the onset of deleterious phases such as σ-phase and chromium nitrides. The objective of this investigation was to quantify the seawater pitting corrosion resistance of a type 25Cr SDSS (UNS S32750) and its correlation with microstructure and surface finish before testing. Cyclic potentiodynamic polarization (CPP) testing was used to determine the effect σ-phase on the corrosion response of the system. CPP results were then compared against industry standard practices based on the ASTM G48 Method A test. In addition, CPP tests were conducted at various temperatures, ranging from 25 to 90°C, to determine the effect of deleterious phases on critical pitting temperature (CPT) and overall localized corrosion resistance.The results from this project indicate that the Critical Pitting temperature for standard solution annealed Super Duplex Stainless Steel is 60-70°C. It is also shown that the corrosion resistance is reduced for material that contains sigma phase showing a Critical Pitting Temperature of 40-50°C. The surface treatments seem to have less effect on the values, but pickled surfaces gave a more repeatable result.
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Tudball, A. "Mathematical modelling of work piece heat transfer during rough and finish processing in a steel hot strip mill". Thesis, Swansea University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639265.
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Temperature control is a key requirement for the production of quality steel strip. During hot rolling, various processes are carried out which improve surface and rolling characteristics but which also increase heat extraction from the slab or bar. Moreover, different hot mill configurations at different sites will give rise to different overall thermal behaviour. Temperature control is required to enable the basic properties of the steel strip to be achieved. Rather than concentrate on individual sections of the hot strip mill a custom-written thermal finite element model has been developed for Corus to stimulate the evolving temperature field in the slab and subsequent thinner bar over the entire hot rolling process. Localised cooling effects caused by hydraulic descale sprays, roll coolant, contact conduction, local atmospheric conditions, heat generation due to adiabatic heating of deformed material and rolling friction, constitute the main features of the model. Modelling of the temperature effects occurring throughout processing can then be used in the optimisation of process operations. This work describes both the practical approach and the numerical method used to develop the model and provides examples of simulations of different hot mill configurations.
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Massé, Thomas. "Study and optimization of a high carbon steel flat wires". Paris, ENMP, 2010. http://www.theses.fr/2010ENMP1672.
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Cette thèse porte sur la modélisation par éléments finis des procédés de mises en forme à froid, que sont le tréfilage et le laminage. Tout d'abord le comportement mécanique des aciers haut carbone a été mesuré grâce à une large campagne d'essais expérimentaux tout au long de cette gamme de mise en forme et une progressive anisotropie mécanique a été observée au cours du tréfilage. Puis, la simulation numérique du tréfilage et du laminage a été réalisée à l'aide de FORGE2005®. Le résultat principal concerne la prédiction de l'élargissement en fin de laminage qui est très imprécise avec une loi isotrope (sous estimation de la largeur de 10%). Cette sous-estimation passe à 5% avec une loi de comportement anisotrope. Ensuite, une troisième partie a porté sur l'étude microstructurale couplée à une analyse des mécanismes d'endommagement des aciers perlitiques au cours du tréfilage et du laminage. L'anisotropie mécanique provient de l'alignement des colonies de perlite au tréfilage et par l'apparition d'une orientation cristallographique préférentielle. Trois mécanismes d'endommagement ont pu être identifiés au cours du tréfilage. Lors du passage au laminage, les cinétiques de propagation de l'endommagement sont modifiées. La simulation a permis d'apporter des informations supplémentaires et de valider les observations expérimentales. Enfin, des calculs d'optimisation du tréfilage ont été effectués et ont permis d'étudier la sensibilité des fonctions objectifs (endommagement et force de tréfilage) aux paramètres d'optimisation (géométrie de filière). De plus, cette étude a mis en évidence que les solutions optimales diffèrent en fonction du choix de la fonction coût et qu'il est possible de diminuer l'endommagement sans trop augmenter la force de tréfilage et le risque de ruptureThis thesis deals with the numerical simulation of cold forming processes, i. E. Wire drawing and rolling. First, high carbon steel mechanical behaviour was measured from experiments throughout this range of steel forming and a progressive mechanical anisotropy has been observed during drawing. Secondly, numerical simulations, with FORGE2005®, have been run to simulate the material behaviour during wire drawing and rolling. The main results show that the widening prediction, with an isotropic behaviour law, is not accurate with an underestimation of 10% on the total width. This underestimation is only 5% when an anisotropic behaviour is used. Then, a microstructural study coupled with an analysis of damage mechanisms was done on high carbon pearlitic steels during wire drawing and rolling. The mechanical anisotropy comes from the orientation of the pearlitic colonies in the drawing, and by the emergence of a preferential crystallographic texture. Three damage mechanisms have been identified during drawing. During rolling, damage expansion kinetics are changed because of heterogeneous strain. Simulation enabled to bring further information and to validate previous experimental observations. Finally, drawing optimization calculations have been performed and enabled to study the sensitivity of the cost functions (damage and drawing force) to optimization parameters (drawing die geometry). Moreover this study highlighted that optimal solution depends on the choice of the cost function and identified an opportunity to reduce damage by reducing the die angle without increasing the axial stresses and the fracture risk
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Daltro, Adnauer Tarquínio. "Soldagem a arco elétrico com proteção gasosa em juntas de chapas finas de aço". Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-16092016-160549/.
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O uso de chapas finas de aço, revestidas ou não, tem sido crescente nos últimos anos, principalmente aquelas que tem revestimento à base de zinco. Isto ocorre tanto na indústria automobilística e mecânica como na construção civil, que geralmente fabricam suas peças e estruturas utilizando um procedimento de soldagem. O objetivo deste trabalho é estabelecer procedimentos de soldagem à arco elétrico com proteção gasosa - GMAW - com transferência por curto circuito, para elementos de chapa fina de aço carbono não revestido e aço zincado, de modo a se obter junções de qualidade aceitável e diminuição das distorções decorrentes dos ciclos térmicos presentes durante a soldagem e, consequentemente a redução das tensões residuais. Em termos de qualidade da solda, propões-se uma combinação de consumíveis disponíveis no mercado, de modo a reduzir os defeitos como: porosidade, respingos, trincas e perda de revestimento. No caso das chapas finas de aço zincado, a melhor combinação de consumíveis encontrada foi: arame com baixo teor de desoxidantes, ER70S-3, e como gás de proteção a mistura 8% CO2 + 92% Ar. Quanto à redução e controle das distorções, três técnicas são utilizadas. A técnica que utiliza em escoadouro dinâmico de calor, formado por um jato de gás refrigerador aplicado logo após o arco de solda durante a soldagem, apresentou maior eficiência na redução das distorções, provenientes do ciclo térmico.The thin sheet steels, coated or not, has been widely used nowadays, mainly the hot dip galvanized steel sheets. It\'s observed as in the mechanic and automobilist industry as in the civil construction that in manufacturing of pieces and structures employ welding procedures. The aim of this work is to establish procedures to gas metal are welding with short circuit transfer of thin sheet steel elements, not coated and zinc-coated steel, in order to get junctions of acceptance quality and reduction of welding stress and distortion. This distortion arise of the thermal cycles that occur during the welding. In terms of the weld quality is defined the best consumables combination available in the market, in such a way to reduce the weld defects like porosities, spatters, cracks and loss of covering. To galvanized steel sheets, the combination: wire ER70S-3 and mixture 8%CO2 + 92% Ar showed the best performance. Three techniques were employed for control and reduce the welding distortion. One that using a spot heat sink following the arc, in this case the cooling jet, was more efficient that others techniques.
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Geslain, Edouard. "Soudage par résistance des tôles fines revêtues : formation du noyau dans un assemblage de trois tôles". Thesis, Lorient, 2018. http://www.theses.fr/2018LORIS481/document.
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Dans l’industrie automobile, les exigences en matière d’émissions polluantes conduisent à alléger les véhicules, notamment en réduisant l’épaisseur des tôles. Ce travail en partenariat avec ArcelorMittal porte sur le soudage par résistance par point de tôles fines d’acier. L’objectif est d’identifier les phénomènes qui induisent les difficultés de soudabilité opératoire rencontrées avec une combinaison dissymétrique de trois tôles revêtues, incluant une tôle très mince galvanisée de moins de 0,6 mm, une tôle de DP600 et une tôle en Usibor® emboutie à chaud. Des observations par caméra infrarouge montrent que les échauffements initiaux se produisent principalement au niveau des interfaces avec la tôle d’Usibor®1500, et que le noyau se forme du côté de cette tôle, loin de la tôle mince. Les valeurs très élevées des résistances de contact électrique et thermique, mesurées aux interfaces avec la tôle d’Usibor®, sont imputables au revêtement Alusi® et sont à l’origine des forts échauffements initiaux observés à ces interfaces. Un modèle numérique, limité aux aspects électrothermiques et développé sur COMSOL Multiphysics®, a permis de montrer que la zone fondue s’initie très rapidement dans la tôle d’Usibor® 1500 sous l’effet des fortes résistances de contact adjacentes, et que son développement en épaisseur et diamètre est piloté par les évolutions des rayons de contact électrode-tôle. Les résistances de contact entre électrode et tôle mince, le profil du courant de soudage et les rayons de courbure des faces actives des électrodes sont les paramètres prépondérants à optimiser pour améliorer la pénétration du noyau dans la tôle minceIn the automotive industry, the requirements for polluting emissions lead to light vehicles, especially in decreasing the steel sheet thickness. This work in partnership with ArcelorMittal focuses on resistance spot welding of steel sheets. The aim is to identify the phenomena that induce operating weldability difficulties encountered with an asymmetrical stack of three coated steel sheets, including a very thin galvanized sheet of less than 0.6 mm, a sheet of DP600, and a hot stamped Usibor® sheet. Infrared camera observations show that the initial heating takes placeat the interfaces with the Usibor®1500 sheet, and that the nugget appears inside this sheet, away from the thin sheet. The very high values of the electrical and thermal contact resistances, measured at the interfaces with the Usibor®1500 sheet, are due to the Alusi® coating and are at the origin of the strong initial heating at these interfaces. A numerical model, limited to the electro- thermal aspects and developed with COMSOL Multiphysics®, shows that the nugget is initiated very quickly in Usibor®1500 sheet under the effect of adjacent contact resistances, and that its development is driven by the evolutions of the electrode-sheet contact areas. The contact resistances between the electrode and the thin sheet, the welding current evolution, and the curvature radius of electrode tips are the most efficient parameters to be optimized to improve the penetration of the nugget in the thin sheet
Livros sobre o assunto "The finest steel"
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Melton, Gil. Steel sculpture: From vision to fine art : forty years of my finest steels. Bloomington, IN]: Xlibris Corporation, 2012.
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Holder, Edison. Desperadoes Musical Conquerors: History of Trinidad and Tobago's Finest Steel Orchestra. Outskirts Press, Incorporated, 2020.
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Steel Connection Analysis. Wiley & Sons, Incorporated, John, 2018.
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Rugarli, Paolo. Steel Connection Analysis. Wiley & Sons, Limited, John, 2018.
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Rugarli, Paolo. Steel Connection Analysis. Wiley & Sons, Limited, John, 2018.
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Ellobody, Ehab. Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges. Elsevier Science & Technology Books, 2023.
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Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges. Elsevier Science & Technology Books, 2014.
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Ellobody, Ehab. Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges. Elsevier Science & Technology Books, 2014.
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Ellobody, Ehab. Finite Element Analysis and Design of Steel and Steel-Concrete Composite Bridges. Elsevier Science & Technology, 2023.
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Naiqian, Feng. Multifunctional Concrete Technology. Materials Research Forum LLC, 2022. http://dx.doi.org/10.21741/9781644901991.
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The book reviews production and applications of high- and ultrahigh strength multifunctional concrete. The use of various coarse and fine aggregates are covered, as well as ultrafine powders, new superplasticizers, anti-rust agents for steel bars and electrochemical protection technology.
Capítulos de livros sobre o assunto "The finest steel"
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Weiser, Ingo Felix, Tim Herrig e Thomas Bergs. "A Model Calculation of CO2 Emissions Saving Potential for Fine Blanking of Inductively Heated Sheet Metal with Comparison of the Product Variants". In Lecture Notes in Mechanical Engineering, 685–93. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-28839-5_77.
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AbstractThe steel processing industry must increasingly question itself with regard to environmental aspects, especially for automobile production. As a consequence of the resulting lightweight construction requirements in the automotive sector, manufacturing processes of industrial relevance must deal with high-strength steels. In case of fine blanking, the process faces its limits already when processing medium-high tensile strength steels because of high tool wear or failure. A promising approach to overcome these process limits is the introduction of heat into the processed metal sheet in order to lower the flow stress of the steel. In order to estimate the sustainability of a fine blanking process with inductively heated sheets, the energy input during heating is investigated in this work. An energy balance is drawn for fine blanking of inductively heated sheets. A further component of the work is the subsequent use phase of the components produced in this way. A consideration of the greenhouse gas emissions savings potential by fine blanking in the German automotive production shows possible future perspectives for manufacturing. It could be found that by substituting standard fine blanking process by inductively heated fine blanking of higher strength steels greenhouse gas emissions can be decreased.
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Weng, Yuqing. "Overview". In Ultra-Fine Grained Steels, 1–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-77230-9_1.
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Tian, Zhiling, e Yun Peng. "Welding of Ultra-Fine Grained Steels". In Ultra-Fine Grained Steels, 494–566. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-77230-9_10.
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Yang, Zhongmin. "Refinement of Austenitic Microstructure and Its Influence on γ→α Transformation". In Ultra-Fine Grained Steels, 53–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-77230-9_2.
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Dong, Han, e Xinjun Sun. "Deformation Induced Ferrite Transformation". In Ultra-Fine Grained Steels, 86–136. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-77230-9_3.
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Kang, Yonglin, e Delu Liu. "Microstructure Refinement of Steels by TSCR Technology". In Ultra-Fine Grained Steels, 137–234. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-77230-9_4.
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He, Xinlai, e Chengjia Shang. "Microstructure Fining Theory of Low- carbon Bainitic Steel". In Ultra-Fine Grained Steels, 235–99. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-77230-9_5.
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Hui, Weijun. "Microstructure Refining and Strengthening of Martensitic Steel". In Ultra-Fine Grained Steels, 300–349. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-77230-9_6.
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Bai, Bingzhe. "Carbide-free Bainite/Martensite (CFB/M) Duplex Phase Steel". In Ultra-Fine Grained Steels, 350–430. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-77230-9_7.
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Wang, Xinhua. "Extra Low Sulfur and Non-metallic Inclusions Control for Ultra Fine Grain High Strength Steels". In Ultra-Fine Grained Steels, 431–72. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-77230-9_8.
Texto completo da fonteTrabalhos de conferências sobre o assunto "The finest steel"
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Bobzin, K., L. Zhao, M. Öte e T. Königstein. "Highly Economical Fe-Based Protective Coating System by Novel Material Design and Full Utilization of the Atomized Powder". In ITSC 2016, editado por A. Agarwal, G. Bolelli, A. Concustell, Y. C. Lau, A. McDonald, F. L. Toma, E. Turunen e C. A. Widener. DVS Media GmbH, 2016. http://dx.doi.org/10.31399/asm.cp.itsc2016p0700.
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Abstract In this work, the aim is to develop a cost-effective coating to protect cast iron and carbon steel from corrosion and wear. An alloy with a composition of FeCr25Mn10BC was designed that could be readily converted to powder form by gas atomization. Different sized powders were produced, characterized, and subsequently sprayed using a three-cathode air plasma generator. It was found that fine powders with fractions of -25 +10 μm and -10 μm had a much higher affinity to oxidation than coarser ones. Nevertheless, using suitable parameters, dense coatings with low oxide content could be realized even with the finest powder. The results show that full utilization of the powder is achievable due to the wide parameter window of three-cathode plasma spraying and that the average deposition efficiency is more than 70%. In addition to savings in material and processing costs, the new alloy system provides greater wear resistance than stainless steel coatings and exhibits significantly higher corrosion resistance than unprotected cast iron and carbon steel.
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Gaudet, Michael J., e Warren J. Poole. "Tensile and Fracture Properties of X80 Steel Microstructures Relevant to the HAZ". In 2012 9th International Pipeline Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ipc2012-90485.
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The girth welding of steel pipelines creates a substantial heat affected zone (HAZ) within the base pipeline steel. The HAZ can be considered to be a complex graded microstructure. While there is significant concern as to the fracture and mechanical properties of the HAZ as whole, detailed knowledge about the mechanical properties of the individual microstructures is lacking. For this study, X80 is heat treated in a Gleeble simulator to create samples of bulk microstructures with differing amounts and morphologies of bainite, ferrite and martensite-retained austenite (MA) with a total of 8 microstructures being investigated. The heat treatments were selected specifically to control the level of niobium in solid solution; that is to control whether niobium was fully in solution or contained mainly in niobium carbonitride precipitates. From the heat treated samples a matching tensile and fracture specimens were made. The strongest microstructure proved to be the finest bainitic microstructure, while the lowest strength microstructure was the coarsest bainite sample containing a significant amount of martensite-retained austenite connected along grain boundaries. The fracture behaviour at ambient temperature was studied using the Kahn tear test. The Kahn tear test is a machine notched, thin-sheet, slow strain rate fracture test which has the advantage of being a simple test to conduct. All Kahn tests failed in a ductile manner and it showed that the sample with the coarse bainite, with a connected martensite-retained austenite phase had the lowest unit propagation energy and tear strength while the fine, fully bainitic sample had the highest unit propagation energy and tear strength. Further investigation using SEM measurements of the final fracture surface from the tensile test to determine the tensile toughness. A comparison of the tensile toughness and unit propagation energies showed that there was a complex relationship between the two measurements. However, the samples which had the highest content of MA gave the in lowest unit propagation energy.
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Nagai, Yoshihide, Hidenori Fukami, Hajime Inoue, Takao Nakashima, Akihiko Kojima, Toshiyuki Kajitani, Toshihiko Adachi e Yuzuru Yoshida. "Production of High-Strength and High-Toughness Steel for Offshore Structures". In ASME 2003 22nd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2003. http://dx.doi.org/10.1115/omae2003-37436.
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By the utilization of new fine particles, steels refining the heat affected zone (HAZ) structure have been developed. This has made possible the mass-production of offshore structural steels which have high-strength of 460–500N/mm2 in yield strength (YS) and excellent crack-tip opening displacement (CTOD) properties. These newly developed steels for offshore structures have been mass-production to over 45,000 tons. The new particles are dispersed finely in the developed steels and show a strong pinning effect. The newly developed steels also use the intragranular ferrite (IGF) like titanium oxide bearing steel (TiO steel). In mass-production heats, γ grain size is restricted below 200 μm under conditions of 1400°C for 60 seconds. The improvement of HAZ toughness and the utilization of the thermo-mechanical control process (TMCP) has restrained the increase in carbon equivalent (Ceq,PCM) far as possible. By application of these technologies, it has been possible to mass-produce steels with high-strength, excellent CTOD properties and good weldability. As for steel plates of YS500N/mm2, the production of steel plates up to 70mm in thickness was carried out. The properties of welded joints for the 70mm-thick plates of YS500N/mm2 steel have been evaluated under heat input in 0.7kJ/mm of flux-cored are welding (FCAW) and 3.5kJ/mm of sub-merged arc welding (SAW). They have shown excellent CTOD and Charpy impact properties at welded joints; and have moreover indicated good weldability when PCM has been restricted to 0.22% or lower.
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Fukuta, Yuichi, Hiroshi Kanasaki, Seiji Asada e Takehiko Sera. "Proposal of Surface Finish Factor on Fatigue Strength in Design Fatigue Curve". In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28601.
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The published papers related to the effects of surface finish on fatigue strength are reviewed in order to formulate its factor in the design fatigue curve in air environment. Firstly, some of regulations and literatures were examined to verify the surface finish effect on fatigue strength and formulation of that in design fatigue curve. The fatigue strength of carbon and low alloy steels is decreased with an increase of its surface roughness and tensile strength but that of stainless steel is not decreased except for special conditions. After screening the data of carbon and low alloy steels, a surface finish factor is formulated with these data which is a function of tensile strength, surface roughness and mean stress.
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Thomas, Arpit, e Anant Kumar Singh. "Magnetorheological Nano-Surface-Finishing of Tapered Cavity of Chrome Steel Punch". In ASME 2019 14th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/msec2019-2851.
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Abstract The need for finishing chrome steel punch has drastically increased in order to obtain products with high quality and productivity. Chrome steel finds its application in manufacturing of punch and dies because of its higher hardness as varies up to 62 HRC. The paper is focused on improving the productivity of chrome steel punch through improving the surface finish using magnetorheological finishing process with a solid rotating tool core. The traditional method used for finishing of the chrome steel punch involves diamond lapping where machining marks and surface micro cracks are observed. In punching operation, the punch undergoes adhesive wear which can be controlled if the surface finish of the punch is improved. The surface finish obtained after diamond lapping process is up to 408 nm range. In present work, the further finishing of the tapered cavity of chrome steel punch is carried out. The chrome steel punch workpiece is rotated in a direction opposite to the rotation of the tapered tool tip surface in order to efficiently perform the finishing operation. The final surface roughness value of the flat surface of circular tapered punch is obtained as 26 nm from 420nm while the roughness value of the tapered surface is obtained as 22 nm from 408 nm in 90 minutes of finishing.
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Shih, Hua-Chu. "Galling and Die Build-Up in Forming Uncoated, Cold-Rolled Advanced High-Strength Steels (AHSS)". In ASME 2015 International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/msec2015-9237.
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Uncoated advanced high strength steels (AHSS) are being used for non-exposed automotive applications where high strength is required. Due to higher contact pressures and friction forces between the tooling and sheet steel, increased die wear, die build-up and sheet steel surface galling have been observed. Although various countermeasures have been adopted in production to address these issues, the stamping die tryout process has not been revised accordingly. Proper heat treatment of uncoated tryout dies is required to prevent wear in stamping uncoated, cold-rolled AHSS. Whether die build-up and sheet steel surface galling occur depends on the steel surface condition. The intent of this study is to investigate the effects of steel surface topography on die build-up, sheet steel surface galling and friction in forming uncoated cold-rolled AHSS. DP590 and DP980 with different thickness and different finish rolled textures were tested with the bending under tension (BUT) tester to study these effects. A reciprocal cyclic bend test system (CBTS) of modifying bending under tension test was used to investigate wear and build-up between different surface texture steels in a production condition. Results indicate that the finish roll surface texture is found to be the root cause for the die build-up and steel surface galling that occurs during forming with uncoated dies. The ground-roll surface is the worst in terms of galling and build-up while the Electro-Discharge Textured (EDT) surface is the best. The surface parameters Skewness (Rsk) and Kurtosis (Rku) are found to be able to assess steel galling and die build-up behaviors for uncoated cold rolled AHSS using the uncoated D2 die. A surface with Rsk larger than −0.5 and Rku less than 3 can prevent galling and die build-up in the die tryout process, which is recommended to finish roll the uncoated cold rolled AHSS.
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Ramesh, Anand, Jeffrey D. Thiele e Shreyes N. Melkote. "Residual Stress and Sub-Surface Flow in Finish Hard Turned AISI 4340 and 52100 Steels: A Comparative Study". In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0747.
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Abstract This paper presents the results of an experimental study intended to compare the surface integrity of finish hard turned AISI 4340 and 52100 steels (57 Rc). Specifically, the paper addresses residual stresses, white layer formation and workpiece sub-surface plastic flow in hard turning of AISI 4340 by varying the feed rate and the tool cutting edge geometry. The results are compared with those obtained for AISI 52100 steel under identical conditions in a previous study (Thiele and Melkote, 1999a-b). In contrast to AISI 52100, no white layers were produced in AISI 4340 when cutting at low feed rates with a chamfered tool. Also, unlike AISI 52100, no clear evidence of an over-tempered layer was found in AISI 4340 steel under all conditions studied. Surface residual stresses in AISI 4340 steel were more compressive than AISI 52100 steel, whereas the magnitude and depth of the peak compressive residual stress tended to be greater for AISI 52100 steel. These observations are attributed to the different mechanical, thermal, and metallurgical responses of the two hardened steel alloys to machining, and are in part due to the significant difference in the carbon content of the two alloys.
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Grubb, D. G., S. C. Jagupilla e M. Wazne. "Immobilization of Cadmium (Cd) and Zinc (Zn) Using Steel Slag Fines". In Geo-Chicago 2016. Reston, VA: American Society of Civil Engineers, 2016. http://dx.doi.org/10.1061/9780784480168.051.
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Jagupilla, S. C., D. G. Grubb e M. Wazne. "Immobilization of Sb(III) and Sb(V) Using Steel Slag Fines". In GeoCongress 2012. Reston, VA: American Society of Civil Engineers, 2012. http://dx.doi.org/10.1061/9780784412121.409.
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Shinozaki, Ippei, e Yasushi Hasegawa. "Precipitation Strengthening by the Nitrides in High Cr Containing Ferritic Creep Resistant Steels". In AM-EPRI 2013, editado por D. Gandy e J. Shingledecker. ASM International, 2013. http://dx.doi.org/10.31399/asm.cp.am-epri-2013p1071.
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Abstract High nitrogen steel was manufactured by solid state nitriding and Laminate- rolling at laboratory to study the nitride morphology and creep properties through the TEM, EPMA and creep strain test. Nitriding made the nitride dispersing steels possible. Solid state nitriding of thin plates and those laminate rolling enabled the high nitrogen containing thick plate steel. Precipitated coarse nitrides during the nitriding resolved by normalizing and re-precipitated by tempering finely. Needle type VN was detected in V containing high nitrogen steels. Its coherency seems to affect the creep strength significantly. V precipitated steels indicated the higher creep strength than the steels without VN precipitation. Thermodynamically stable precipitates like VN increases the creep rupture strength. Ti and Zr containing high nitrogen steels also will be evaluated and discussed by the presentation.
Relatórios de organizações sobre o assunto "The finest steel"
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Williams, D., e W. Maxey. NR198506 Evaluation of an X70 Low-Carbon Bainitic-Steel Pipe. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), outubro de 1985. http://dx.doi.org/10.55274/r0011411.
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A 24-inch-diameter x 0.75-inch-wall X70 low-carbon bainitic-steel pipe was evaluated to obtain an independent measurement of pipe properties and to examine metallurgical characteristics that may affect behavior in gas-transmission service. The steel from which the pipe was produced was processed using advanced steelmaking methods to insure cleanliness but apparently was not treated for sulfide shape control since no sour gas exposure in service was anticipated. Primary microalloying additions in this high manganese steel, other than columbium, were titanium and boron. Titanium was added to form a TiN dispersion during continuous casting to aid in the control of austenite grain size during slab rolling. Boron was added to suppress the transformation of austenite to ferrite or pearlite during and following controlled rolling, so as to promote formation of bainite. Heavy controlled rolling at temperatures below the austenite recrystallization temperature, and finish rolling at temperatures perhaps as low as 1290 F were used to develop a very fine grain size in the bainite.
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Hill, N. F. Report of ``Time Saver`` surface finish tests on Czech steel samples. Office of Scientific and Technical Information (OSTI), novembro de 1995. http://dx.doi.org/10.2172/132726.
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Patchett, B. M., e A. C. Bicknell. L51706 Higher-Strength SMAW Filler Metals. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), dezembro de 1993. http://dx.doi.org/10.55274/r0010418.
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The welding of high strength steels in general, and for pipeline fabrication in particular, has shown that cracking due to hydrogen absorption during welding is more complex in these steels than in older, lower strength steels. In older steels, primary strengthening was accomplished with carbon, which caused hydrogen cracking in the base metal HAZ under reasonably predictable conditions involving microstructure, residual stress and hydrogen level. Pipeline steels were and are in the vanguard of change in strengthening philosophy. The change involves two areas of steel making, chemical composition and deformation processing. Pipeline steels now contain low carbon levels, in many cases less than 0.10%, and the resulting lack of strength is reclaimed by adding higher alloy levels to promote solution hardening (e.g. Mn), precipitation hardening (e.g. Cb, Cu) or transformation hardening (e.g. MO). In addition, alloy elements are added to improve toughness at high strength levels (e.g. Ni). At the same time, improvements have been made in reducing impurity and residual element levels, notably for S, P and O and N. Limitations on the effects of alloying additions on strength and toughness encouraged the use of deformation processing, primarily during rolling, to promote fine-grained microstructures to increase strength andtoughness simultaneously. Electrodes for the SMAW process have been developed for welding high-strength pipeline steels by using core wires made from high-strength microalloyed skelp extruded with cellulosic (Exx10) and low hydrogen (Exx16) flux coatings. The required alloy elements for high-strength deposits were therefore obtained from the core wire and not ferroalloy powders added to the flux, as is standard industrial practice. The idea behind this change was two fold: to avoid the possibility of introducing impurities from the varying sources of ferro alloy powders, including oxygen from the oxidized powder surfaces, and also to provide a closer match of the microalloy level to modern pipeline steel chemistries. The unknowns in this work were the effects of lower impurities/similar alloy content on the mechanical properties in the cast microstructure of a weld, compared to a pipe, and of the effect on electrode welding behaviour of a flux containing no ferro powders other than FeSi.
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Rahman, M. M., e K. N. Strafford. USA09-01 Appraisal and Assessment of Factors Involved in the Maintenance of the Integrity of Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), setembro de 1992. http://dx.doi.org/10.55274/r0011770.
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The experimental work reported in this thesis was aimed at investigating the relative importance of surface-finish and condition on: (1) susceptibility to stress corrosion cracking, and (2) FBE coating performance for X-65 pipeline steel.
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Waisel, Yoav, Bobbie McMichael e Amram Eshel. Decision Making within Plant Root Systems. United States Department of Agriculture, março de 1996. http://dx.doi.org/10.32747/1996.7613030.bard.
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Architecture of a root system is the expression of the potential of various root types to branch, to grow and to coordinate with other plant organs, under the specific limitations of the environmental conditions. The present investigation has proven the following points. 1) Genotypes with different types of root systems were identified. The growth patterns of their roots and the distribution of laterals along their main axes were recorded. 2) The patterns of development of the root systems of four cotton genotypes, throughout the entire life cycle of the plants, were described, even at such a late stage of development when the total length of the roots exceeded two kilometers. To the best of our knowledge, this is the first time that an analysis of this type is accomplished. 3) The development of root systems under restrictive soil conditions were compared with those that have developed under the non-restrictive conditions of aeroponics. Results indicate that in the absence of the mechanical impedance of the soil, cotton plants develop single roots that reach the length of 6 m, and have a total root length of 2000 m. Thus, root growth is strongly inhibited by the soil, with some root types being inhibited more than others. 4) One of the important decisions, in constructing an operational root system architecture of mature plants, is the shift of the balance between various root fractions in favor of the very fine roots. 5) Root system architecture is determined, in part, by the sites of initiation of the lateral roots. This is determined genetically by the number of xylem archs and by the totuosity of the stele. Selection for such traits should be sought.
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Dodd, Hope, David Bowles, John Cribbs, Jeffrey Williams, Cameron Cheri e Tani Hubbard. Aquatic community monitoring at Herbert Hoover National Historic Site, 2008?2017. National Park Service, 2024. http://dx.doi.org/10.36967/2303263.
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Land use changes that degrade water quality and stream habitat can negatively impact aquatic communities. Monitoring trends in aquatic community composition and habitat conditions is a robust way to assess stream integrity and health. Herbert Hoover National Historic Site (NHS) is in eastern Iowa where dominant land use consists of row-crop and grassland agriculture. A portion of an unnamed tributary of the West Branch of Wapsinonoc Creek, known as Hoover Creek, flows through the park. In 2008, the Heartland Inventory and Monitoring Network (Heartland Network) of the National Park Service (NPS) began monitoring aquatic communities (fish and invertebrates), physical habitat, and water quality at Hoover Creek within the park. This report summarizes four years of data to assess the baseline conditions of Hoover Creek within Herbert Hoover NHS. Aquatic invertebrate taxa richness ranged from 21 to 32 among all years monitored. Three of these taxa are sensitive to poor water quality and habitat conditions. The invertebrate community was dominated by true flies in the Chironomidae family, Oligochaete worms, and mayflies in the Baetidae family. These taxa are all tolerant of poor water quality and habitat conditions. However, in 2011, the sensitive caddisfly Ceratopsyche was also abundant. Mean Hilsenhoff Biotic Index values indicated the invertebrate community fluctuated over time, ranging from fairly poor in 2017 to good condition in 2011. Ten fish species were collected at Hoover Creek across the four years sampled with seven of those species found in all years. All fish species collected were either moderately tolerant or tolerant to poor habitat and water quality conditions; the community was dominated by johnny darter (Etheostoma nigrum), creek chub (Semotilus atromaculatus), and blacknose dace (Rhinichthys atratulus). Based on the Index of Biotic Integrity developed for Iowa streams, the fish community ranged from fair condition in 2008, 2014, and 2017 to good condition in 2011. Hoover Creek was found to have predominately fine to medium gravel substrate with high embeddedness, and banks were steep and tall and consisted of fine silt substrate. With the exception of turbidity after a rain event in 2008, water quality parameters were within state standards. The four years of stream biota data coupled with habitat data should form a good baseline for assessing changes or trends in the aquatic community and overall stream health of Hoover Creek.
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Rosse, Anine. Stream channel monitoring for Wind Cave National Park 2021 Data report. National Park Service, janeiro de 2023. http://dx.doi.org/10.36967/2296623.
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The Northern Great Plains Inventory and Monitoring Network (NGPN) began stream channel monitoring in Highland Creek at Wind Cave National Park (WICA) in 2021. This data report summarizes the data collected during the 2021 season pertaining to watershed, reach, and physical habitat. After data are collected for at least four cycles, trends may be reported. This report covers three main areas: 1) Reporting on upland channel characteristics data that may affect habitat such as: land cover, drainage area, and total stream length; 2) Reporting of geomorphic dimensions such as: channel widths, bank angles, vegetative cover, reach slope, measures of bank stability; and 3) Determining physical habitat characteristics such as: size and distribution of bed sediment, large woody debris, and canopy cover. Indices, benchmarks, and other studies are provided in the table for informational purposes to help put Highland Creek’s measurements in context but should not be considered as a reference condition. Upland characteristics of the watershed indicate high natural land use cover (forest, grassland, and shrubland) with little development in the area. Reach characteristics include bank cover, heights, bank stability index, and vegetative cover. In addition to animal-induced erosion of the banks, bank sloughing and widening are occurring. Angles are steep, and there are some sandy banks that are unstable. When plots are revisited in three years, there will be greater understanding of the processes at play and the condition of the stream. Physical characteristics include median particle size, percentage fine substrate, geomorphic units, and canopy cover. Gravel substrate still covers much of the stream; there are wide meanders in the stream bed; and a variety of geomorphic channel units (pool, riffle, run) occur in the creek all of which are indicators of healthy habitat. While there is an absence of large woody debris and canopy cover is low, many grassland streams in good condition can have similar characteristics. More data are needed to fully assess those components and determine a suitable reference condition that can be used to later assess the status and trends of Highland Creek. The reach data contained in this report are specific to a short 150-m segment of Highland Creek and cannot be extrapolated to conditions elsewhere in the creek or to the park in general. Bank erosion and bank instability were observed along the majority of transects at site WICA SCM 001.
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STABILITY PERFORMANCE AND WIND TUNNEL TEST OF STEEL HYPERBOLIC COOLING TOWER CONSIDERING SKINNED EFFECT. The Hong Kong Institute of Steel Construction, setembro de 2023. http://dx.doi.org/10.18057/ijasc.2023.19.3.10.
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With the development of industry, cooling towers play a very important role in thermal power generation, and steel cooling towers are being used more widely. The surface of cooling towers is covered with profiled panels, and the skinned effect on the mechanical performance and stability of the structure should be considered. At present, most studies on steel cooling towers have not considered the skinned effect. In steel cooling towers, the skin panels are usually connected to members by self-tapping screws., the shearing test of self-tapping screw connection is carried out considering different screw diameters and plate thicknesses to obtain the shear stiffness of the screws. Then, three FE models of steel hyperbolic cooling towers are established and compared: in Mode–1, the skin panel is not considered; in Model–2, the panel and the member node are rigidly connected; in Model–3, the spring elements are established to simulate the shearing and tension stiffness of self-tapping screws connecting skin panel and members. Based on the finest Model–3, a parametric analysis is done to investigate the effect of the skinned effect on the overall structural stability. Considering different landform types and the roughness of the inner and outer surfaces, a total of 18 measurement conditions are tested in the wind tunnel to study the outer and internal wind pressure coefficients. Furthermore, based on the wind tunnel test, the wind-induced response analysis of steel hyperbolic cooling towers is performed.
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APPLICATION RESEARCH OF V CONTAINING HIGH STRENGTH WEATHERING STEEL IN STEEL STRUCTURE BUILDING. The Hong Kong Institute of Steel Construction, agosto de 2022. http://dx.doi.org/10.18057/icass2020.p.090.
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Application research of V containing high strength weathering steel in steel structure building was conducted. The research shows that: adding 0.04% V into weathering steel can lead to grain refinement of ferrite, thereby improving steel performance. Fine polygonal ferrite can make for obvious yield platform, and front cooling method can make V(C, N) precipitation in ferrite fine and dispersive to enhance dislocation pinning, which can further enhance yield effect. In this research V containing weathering steel can realize 500MPa of strength grade, 0.84 of yield ratio, 26.0% of elongation, 3.0% of yield point elongation, 225J of -20℃ impact value (three quarters size). The combination property can satisfy earthquake resistant behavior requirement of steel structure building, and realize replacement of low strength steel for steel structure building, thereby reducing material thickness and weight to realize purchase cost reduction. Cyclical soaking corrosion experiment was conducted, when atmosphere corrosion index of tested steel is around 6.0, the relative corrosion ratio comparing to Q355B is around 40%, which indicates good atmosphere corrosion resistance. In cyclical soaking corrosion experiment, v containing weathering steel for steel structure can realize 5.9g/(m2·h) of 72h average weight loss and 43.4% of relative corrosion ratio, the atmosphere corrosion resistance is good, exposed application of v containing weathering steel for steel structure in industrial atmosphere can obviously reduce rust protection and reduction cost of steel structure building
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LOW-CYCLE FATIGUE PROPERTIES OF AUSTENITIC STAINLESS STEEL S30408 UNDER LARGE PLASTIC STRAIN AMPLITUDE. The Hong Kong Institute of Steel Construction, março de 2022. http://dx.doi.org/10.18057/ijasc.2022.18.1.10.
Texto completo da fonteResumo:
The application of stainless steel materials in civil structures for seismic protection lies in its low-cycle fatigue characteristic. However, the data of existing research are mainly based on the low-cycle fatigue in small strain amplitudes. To this end, we perform low-cycle fatigue testing of Austenitic stainless steel S30408, which has low yield point and good elongation performance, under the cyclic load with a maximum strain amplitude reaching up to 5%, to fill the gap. The stress-strain response characteristics of the stainless steel material under the cyclic load are analyzed; then, the parameters of the strain-fatigue life relationship and the cyclic-plastic constitutive model used for FEA simulation are extracted. Results show that the stainless steel’s stress-strain curve is nonlinear without a yield plateau, thus presenting a high strength yield ratio and ductility. The hysteresis loops of the material are plump with a shuttle shape and are symmetric to the origin, indicating a fine energy dissipation capacity. The skeleton curve under cyclic loading with cyclic hardening can be significantly reflected by the Ramberg Osgood model, which is affected by the strain amplitude and loading history; it is also different from the monotonic tensile skeleton curve. The strain-fatigue life curve fitted by the Baqusin Manson Coffin model can predict the materials’ fatigue life under different strain amplitudes. The mixed hardening model, including isotropic and kinematic hardening, based on the Chaboche model, is able to simulate the cyclic stress-strain relationship. Further, its parameters can provide basic data information for the seismic design of civil structures when Austenitic stainless steel S30408 is used.