Journal articles: 'Austenite residua'

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Hedström, Peter, Jonathan Almer, Ulrich Lienert, and Magnus Odén. "Evolution of Residual Strains in Metastable Austenitic Stainless Steels and the Accompanying Strain Induced Martensitic Transformation." Materials Science Forum 524-525 (September 2006): 821–26. http://dx.doi.org/10.4028/www.scientific.net/msf.524-525.821.

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The deformation behavior of metastable austenitic stainless steel AISI 301, suffering different initial cold rolling reduction, has been investigated during uniaxial tensile loading. In situ highenergy x-ray diffraction was employed to characterize the residual strain evolution and the strain induced martensitic transformation. Moreover, the 3DXRD technique was employed to characterize the deformation behavior of individual austenite grains during elastic and early plastic deformation. The cold rolling reduction was found to induce compressive residual strains in the austenite along rolling direction and balancing tensile residual strains in the ά-martensite. The opposite residual strain state was found in the transverse direction. The residual strain states of five individual austenite grains in the bulk of a sample suffering 2% cold rolling reduction was found to be divergent. The difference among the grains, considering both the residual strains and the evolution of these, could not be solely explained by elastic and plastic anisotropy. The strain states of the five austenite grains are also a consequence of the local neighborhood.

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Shiekhelsouk, M. N., Véronique Favier, Karim Inal, Sebastien Allain, Olivier Bouaziz, and M. Cherkaoui. "Residual and Internal Stress States in Duplex Steel with TWIP Effect." Materials Science Forum 524-525 (September 2006): 833–38. http://dx.doi.org/10.4028/www.scientific.net/msf.524-525.833.

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A new variety of duplex steels with superior mechanical properties has been studied. They exhibit a very interesting combination of strength (tensile strength of 680 MPa) and ductility values (more than 45% total elongation) due to the competition between different plasticity mechanisms. These steels contain two phases: austenite and ferrite and are characterized by low stacking fault energy at room temperature. In this work, four duplex steels with different chemical composition and phase volume fraction are studied. Residual and internal stresses in each phase were determined using the classical X-ray diffraction sin²ψ method. In the as-received state, both longitudinal and transverse residual stresses are in compression (until -350 MPa) for the ferrite and in tension (until +410 MPa) for the austenite. However, residual stresses in the austenitic phase decrease when its volume fraction increases. Moreover, internal stress distribution in one alloy was determined by X-ray diffraction during an in situ tensile test. The austenitic phase stress along the loading direction is higher than the macroscopic applied one, which is higher than the ferritic stress state, verifying a mixture rule and consistent with the initial residual stresses. For an applied macroscopic strain of about 1%, the austenite phase is subjected to a stress of about 600 MPa whereas the stress in the ferritic phase is about 300 MPa. It was also observed that as macroscopic strain increases, stress difference between the austenite and the ferrite decreases.

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Stone, H. J., M. J. Peet, H. K. D. H. Bhadeshia, P. J. Withers, S. S. Babu, and E. D. Specht. "Synchrotron X-ray studies of austenite and bainitic ferrite." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 464, no. 2092 (January 29, 2008): 1009–27. http://dx.doi.org/10.1098/rspa.2007.0201.

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High-resolution synchrotron X-ray diffraction has been used to conduct in situ studies of the temporal evolution of phases during the isothermal growth of bainite. Two populations of austenitic material were identified: one corresponding to the initial austenite and the other to the carbon-enriched austenite associated with the bainitic ferrite. The observed lattice parameters and the asymmetry of the peaks from the residual austenite have been interpreted in terms of the carbon partitioning due to the transformation. The results are contrasted with an earlier study in which the austenite unit cell appeared to split into two distinct densities prior to the onset of transformation.

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Katemi, Richard J., and Jeremy Epp. "Influence of carbonitriding conditions on phase composition and residual stresses for 20MnCr5 low alloy steel." Tanzania Journal of Science 47, no. 2 (May 26, 2021): 790–99. http://dx.doi.org/10.4314/tjs.v47i2.34.

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This paper reports an investigation of the influence of carbonitriding conditions for 20MnCr5 low alloy steel. Three gaseous carbonitriding conditions were investigated based on different carbon and nitrogen potentials to attain varying levels of carbon between 0.62 and 0.93% mass, whereas for nitrogen between 0.19 and 0.26% mass at the surface. Analysis of retained austenite and residual stress distributions was conducted using X-ray diffraction technique. The effective case depth varied between 900 and 1200 µm. The case microstructures were characterized by varying proportions of retained austenite and martensite, while the core contained essentially bainitic microstructures. The maximum amount of retained austenite which occurred at a depth of 50 µm from the subsurface ranged between 30 and 70% mass and significantly influenced the level of surface micro-hardness whereas the core hardness remaining relatively constant at 450 HV1. High values of residual stresses in martensite phase were observed. The signs, magnitudes, distributions and location of maximum compressive residual stresses were highly influenced by the maximum fraction of retained austenite. Retained austenite of 30%, 50% and 70% mass at the surface lead to peak compressive residue stresses of -280, -227, and -202 MPa at depths of 555, 704, and 890 μm, respectively. Keywords: Carbonitriding, retained austenite, martensite, residual stress, XRD.

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Tsuchida, Noriyuki, Kenzo Fukaura, Yo Tomota, Atsushi Moriai, and Hiroshi Suzuki. "Tensile Deformation Behaviors of Metastable Austenitic Stainless Steels Studied by Neutron Diffraction." Materials Science Forum 652 (May 2010): 233–37. http://dx.doi.org/10.4028/www.scientific.net/msf.652.233.

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Tensile deformation behaviors of three austenitic stainless steels, JIS-SUS310S, 304 and 301L, were studied by static tensile tests and in situ neutron diffraction. In the mechanical properties obtained by the static tensile tests, the 304 and 301L steels showed better balance of tensile strength and uniform elongation than the 310S one because of TRIP effect. The angular dispersion neutron diffractions with a wavelength of 0.16 or 0.182 nm were performed during stepwise tensile testing by using a neutron diffractometer for residual stress analysis (RESA) at the Japan Atomic Energy Agency. The lattice plane strain, stress-induced martensite volume fraction, dislocation density and so on were estimated by the profile analysis as a function of applied stress. The change in lattice plane spacing for austenite indicated four deformation stages. In the comparison of lattice plane strain among the tested steels, a phase stress caused by the stress-induced martensite seems to overlap the intergranular stress of austenite phase. Judging from the results of profile analysis, the strain partitioning of austenite phase in metastable austenitic steels became larger with increasing of the volume fraction of stress-induced martensite during tensile deformation.

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Prokoshkin, Sergey, Andrey Korotitskiy, Vladimir Brailovski, and K. E. Inaekyan. "Effect of Nanocrystalline Structure and Polygonized Dislocation Substructure on Ti-Ni Martensite Lattice Parameters and Transformation Lattice Strain." Materials Science Forum 584-586 (June 2008): 475–80. http://dx.doi.org/10.4028/www.scientific.net/msf.584-586.475.

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The Ti-50.26 and 50.61at.%Ni alloys were cold-rolled with true strains from e=0.3 to 2.1. Post-deformation annealing in the 200 to 500°C temperature range after a moderate deformation (e=0.3) produced a polygonized dislocation substructure with various dislocation density and subgrain size, while after severe plastic deformation (e=1.7-1.9), a nanocrystalline structure with various grain size was formed in the B2-austenite. An X-ray diffraction study shows that lattice parameters of B19'-martensite formed from (a) partially recovered and polygonized or (b) nanocrystalline austenites differ from the corresponding parameters of the martensite formed from quenched (recrystallized) austenite. This difference increases with nanocrystalline grain refinement and with an increase in residual dislocation density and subgrain refinement. The maximum martensitic transformation strain has the highest value for the martensite formed in recrystallized austenite, and this value decreases with nanograin refinement and with an increase in dislocation density and subgrain refinement.

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Shen, Li Juan, Yong Lin Ma, and Shu Qing Xing. "The Morphology and Content of δ Ferrite in Non-Equilibrium Solidified 0Cr18Ni9 Austenitic Stainless Steel." Advanced Materials Research 535-537 (June 2012): 666–69. http://dx.doi.org/10.4028/www.scientific.net/amr.535-537.666.

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The microsructural and content of δ ferrite in non-equilibrium solidified 0Cr18Ni9 austenitic stainless steel is studied by the coin with the circulating water. The solidified microstructure of the residual δ ferrite in different cooling rate is that during the course of solid-state transformation, austenite grows into ferrite gradually; corresponding to the increase of cooling rate, the microsructural of ferrite is skeletal, network, strip and block. The experiment demonstrates that the content of the residual δ ferrite is increase under the increase of the cooling rate.

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Dankwort, Torben, Julian Strobel, Christoph Chluba, Wenwei Ge, Viola Duppel, Manfred Wuttig, Eckhard Quandt, and Lorenz Kienle. "Martensite adaption through epitaxial nano transition layers in TiNiCu shape memory alloys." Journal of Applied Crystallography 49, no. 3 (May 27, 2016): 1009–15. http://dx.doi.org/10.1107/s160057671600710x.

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Titanium-rich TiNiCu shape memory thin films with ultralow fatigue have been analysed for their structural features by transmission electron microscopy. The stabilization of austenite (B2) and orthorhombic martensite (B19) variants epitaxially connected to Ti2Cu-type precipitates has been observed and found responsible for the supreme mechanical cycling capability of these compounds. Comprehensiveex situandin situcooling/heating experiments have demonstrated the presence of an austenitic nanoscale region in between B19 and Ti2Cu, in which the structure shows a gradual transition from B19 to B2 which is then coupled to the Ti2Cu precipitate. It is proposed that this residual and epitaxial austenite acts as a template for the temperature-induced B2↔B19 phase transition and is also responsible for the high repeatability of the stress-induced transformation. This scenario poses an antithesis to residual martensite found in common high-fatigue shape memory alloys.

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Lin, Shao Pin, Ge Ping Yu, J. Y. Huang, H. J. Chen, R. C. Kuo, E. Wen Huang, and Jia Hong Huang. "The Effect of Shielded Metal Arc and Gas Tungsten Arc Welding Methods on 308L Stainless Steel Weldments." Materials Science Forum 783-786 (May 2014): 2753–57. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.2753.

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Shielded metal arc (SMA) and gas tungsten arc (GTA) weldments were investigated to study the welding effects on the mechanical behavior of 308L austenitic stainless steel weldments, respectively. Both SMA and GTA weldments showed dendritic microstructure. The observed austenitic stainless steel welds solidified to give primary ferrite and secondary austenite as the ferritic-austenitic solidification mode (FA-mode) solidification. However, the lower heat input with larger Cr-versus-Ni ratio in SMA weld process led to lathy ferrite morphology and more residual ferrite in the SMA welds, while vermicular ferrite morphology was shown in GTA weldments. The yield strength of the welds significantly increased with decreasing elongation, which was mainly due to the dual phase strengthening effect after rapid solidification during welding

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He, Jinshan, Shiguang Xu, Wenxin Ti, Yaolei Han, Jinna Mei, and Xitao Wang. "The Pitting Corrosion Behavior of the Austenitic Stainless Steel 308L-316L Welded Joint." Metals 10, no. 9 (September 18, 2020): 1258. http://dx.doi.org/10.3390/met10091258.

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The pitting corrosion resistance of the austenitic stainless steel 308L-316L welded joint was investigated by electrochemical tests. It is found that the weld zone was the most critical for pits to initiate in the welded joint due to relatively instable passive film with few Mo and inhomogeneous passive film induced by multiple (Mn, Al, and Si) oxides and continuous network of 13.94 vol.% δ ferrites. By statistical analysis, 53.8% pits initiated at (Mn, Al, and Si) oxides, 23.0% in austenite, and 23.2% at interface between ferrite and austenite. In addition, heat-affected zone was prone to have pitting corrosion compared with the base metal since residual strain was much higher in the region.

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Berrahmoune, M. Reda, Sophie Berveiller, Karim Inal, and Etienne Patoor. "Residual Stress State at Different Scales in Deep Drawn Cup of Unstable Austenitic Steel." Materials Science Forum 524-525 (September 2006): 95–100. http://dx.doi.org/10.4028/www.scientific.net/msf.524-525.95.

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In this study, residual stresses state at different scales in the 301LN unstable austenitic steel after deep drawing was determined. The first part of the work deals with the characterization of the martensitic transformation during uniaxial loading. The austenite/martensite content which was determined by X-Ray Diffraction increases until a maximum of 0.6 for 30% strain. Internal stress distribution was determined by coupling in-situ tensile tests with sin²ψ method. As soon as martensite appears, the magnitudes of the internal stresses in this phase were found to be 400 MPa higher than in the austenite. To establish a relation between the complex loading path effect and the phase stress state, deep drawing tests were carried out for different drawing ratios. Both macroscopic tangential residual stresses and residual stresses in the martensite were determined. It appears that the macroscopic tangential residual stresses are positive and increase with increasing drawing ratios and the maximum value is located at middle height of the cup. It is about 850MPa for the Drawing Ratio (DR)=2.00. The tangential residual stresses in the martensite were found to be positive in the external face and have a same evolution as the macroscopic ones.

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Peng, Ru Lin, Yan Dong Wang, Guo Cai Chai, Nan Jia, Sten Johansson, and Gang Wang. "On the Development of Grain-Orientation-Dependent and Inter-Phase Stresses in a Super Duplex Stainless Steel under Uniaxial Loading." Materials Science Forum 524-525 (September 2006): 917–22. http://dx.doi.org/10.4028/www.scientific.net/msf.524-525.917.

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Microstresses due to intergranular and inter-phase interactions in an austenitic-ferritic super duplex steel (SAF 2507) under uniaxial compressive deformation have been studied by in-situ neutron diffraction experiments. Lattice strains of several hkl planes of austenite respective ferrite were mapped as a function of sample direction at a number of load levels during loading into the plastic regime and unloading. The analysis of the experimental results has shown that during loading both grain-orientation-dependent and inter-phase stresses were generated under plastic deformation that was inhomogeneous at the microstructural level. Residual stresses depending on the grain-orientation and phase have been found after unloading. The results also indicate stronger intergranular interactions among the studied hkl planes of austenite than those of ferrite.

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Skakov, Маzhyn, Sherzod Kurbanbekov, and Almira Zhilkаshinova. "Research of Electrolytic-Plasma Carbonitriding and Nitriding Influence on Phase Composition of the Stainless Steel." Applied Mechanics and Materials 404 (September 2013): 40–43. http://dx.doi.org/10.4028/www.scientific.net/amm.404.40.

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In the present work we have studied the phase structure of surface modified layer of austenitic steel 12Cr18Ni10Ti after electrolytic-plasma carbonitriding and nitriding. It was determined that the carbonitriding and nitriding with the subsequent hardening formed carbide and nitride phase. Also it is revealed that steel 12Cr18Ni10Ti after the electrolyte-plasma processing has high hardness. The microstructure of samples surface is presented by martensite and residual austenite. Optimum modes of steel 12Cr18Ni10Ti carbonitriding and nitriding by electrolytic-plasma way have been identified.

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Fernandes, Frederico A. P., Thomas L. Christiansen, Grethe Winther, and Marcel A. J. Somers. "Measurement and tailoring of residual stress in expanded austenite on austenitic stainless steel." Materials Science and Engineering: A 701 (July 2017): 167–73. http://dx.doi.org/10.1016/j.msea.2017.06.082.

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Berrahmoune, M. Reda, Sophie Berveiller, Karim Inal, Etienne Patoor, Christian R. Simon, and Jean-Christophe Glez. "Determination of Residual Stresses after Tensile Tests and Deep Drawing of Unstable Austenitic Steel." Materials Science Forum 490-491 (July 2005): 690–95. http://dx.doi.org/10.4028/www.scientific.net/msf.490-491.690.

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The main objective of this work is to contribute to the study of the 301LN unstable austenitic stainless steel by determining the distribution of residual stresses after deep drawing, taking into account the phase transformation. In the first part, kinetics of martensitic transformation are determined for uniaxial loading. Tensile tests are performed at different pre-strains at room temperature for two different strain rates. The austenite/martensite content is measured by X-ray diffraction and is coupled with the determination of residual stresses distribution. In addition, to establish a relation between the complex loading path effect and the residual stresses state, deep drawing are done for different drawing ratios for two different temperatures. Macroscopic tangential residual stresses are determined by the separation technique. It appears that the residual stresses increase with increasing drawing ratios and the maximum value is located at middle height of the cup.

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Bobir, S. V., I. Yu Prikhodko, D. V. Loshkarev, S. S. Zakharchuk, and P. V. Krot. "Analysis of the amount of retained austenite in the structure of steel rolls for sheet rolling." Fundamental and applied problems of ferrous metallurgy, no. 34 (2020): 256–64. http://dx.doi.org/10.52150/2522-9117-2020-34-256-264.

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The amount of residual austenite in martensitic roll steels is an important technological parameter of heat treatment, which affects the performance properties of the rolls. But determining its amount in roll steels is a complex and not fully solved scientific and technical problem. The aim of the work was to comparatively analyze the amount of residual austenite in the structure of alloy steel rolls by X-ray diffraction, ultrasonic methods and metallography analysis. However, the qualitative difference of microstructures in the content of the light phase - austenite, confirms the results of X-ray diffraction analysis. No correlation was found between the austenite content in the samples and their hardness. It was found that the X-ray method, based on the comparison of the intensities of the α- and γ-phase lines of iron, overestimates the value of the amount of residual austenite in some samples of roll steels. The results of the analysis of residual austenite by ultrasound rate showed better convergence. The amounts of residual austenite, calculated on the sample of stainless steel (100% γ-Fe), had reduced values (2.6-4.5%). The most accurate results on the amount of residual austenite gave the use of the established regression dependence with the selected standard (2.7-7.8%). This dependence is obtained at the speed of sound in austenite ~ 4000 m / s. It is determined that the application of the ultrasonic method allows to determine the content of residual austenite in the samples of roll steels quite quickly and accurately.

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Piesova, Marianna, Andrej Czan, Michal Sajgalik, Tatiana Czanova, and Robert Cep. "Experimental Analysis of the Austenitic Phase in Steels by the Application of X-Ray Diffractometry." Technological Engineering 13, no. 2 (December 1, 2016): 34–36. http://dx.doi.org/10.2478/teen-2016-0020.

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Abstract Uniform austenite remaining in the microstructure of the martensitic transformation is called the residual austenite. It is undesirable structure in components, due to its slow decay causes dimensional instability in these components and reducing the hardness. There is a change in volume and it generate internal stress which often appear as cracks. The residual austenite is highly undesirable component in the molded parts, as well as the production of gears and bearing components. The article deals with quantification of residual austenite in steels by using the Average peak method by X-ray diffraction. This method applies four separate peaks to determine the amount of austenite.

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Northwood, Derek O., Lily He, Erin Boyle, and Randy J. Bowers. "Retained Austenite - Residual Stress - Distortion Relationships in Carburized SAE 6820 Steel." Materials Science Forum 539-543 (March 2007): 4464–69. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.4464.

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SAE 8620 steel is typically used in the carburized condition for powertrain applications in the automotive industry, e.g. gears, roller bearings, camshafts. Such steels always contain retained austenite to varying degrees in the as-hardened and also in the tempered microstructures. As well as retained austenite, heat treatment can produce residual stresses, which lead to distortion (size and shape). The intent of this study was to investigate the effect of heat treatment parameters on the amount of retained austenite, residual stress and distortion in carburized SAE 8620 steel. A specially designed specimen, the Navy C-ring, was used for this study. The steel was first normalized prior to machining the Navy C-ring specimens. The specimens were then heat treated by carburizing at 927°C or 954°C (1700°F or 1750°F) at four levels of carbon potential (0.9, 1.0, 1.1, 1.2) followed by oil quenching and tempering at either 149°C or 177°C (300°F or 350°F). The distortion of the C-ring was evaluated by dimensional measurements of the inner diameter, outer diameter, gap width and thickness for size distortion, as well as flatness, cylindricity and roundness for shape distortion. X-ray diffraction (XRD) techniques were used to determine the residual stress and the amount of retained austenite. The amount of retained austenite was also measured by optical metallography. The amount of retained austenite and the residual stress increased with increasing carburizing temperature and carbon potential and decreased upon tempering. There was not a significant further reduction in the amount of retained austenite and residual stress when the tempering temperature was increased from 149°C to 177°C. Distortion was influenced by both the amount of retained austenite and the magnitude of the residual stress. With increasing retained austenite/residual stress, the distortion became more serious. Based on the distortion data for 3 parameters (OD, gap width and flatness) for the quenched and tempered specimens, the amount of retained austenite for minimum distortion was approximately 25%.

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Bassani, Paola, Marco Breda, Katya Brunelli, Istvan Mészáros, Francesca Passaretti, Michela Zanellato, and Irene Calliari. "Characterization of a Cold-Rolled 2101 Lean Duplex Stainless Steel." Microscopy and Microanalysis 19, no. 4 (May 31, 2013): 988–95. http://dx.doi.org/10.1017/s1431927613001426.

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AbstractDuplex stainless steels (DSS) may be defined as a category of steels with a two-phase ferritic–austenitic microstructure, which combines good mechanical and corrosion properties. However, these steels can undergo significant microstructural modification as a consequence of either thermo-mechanical treatments (ferrite decomposition, which causes σ- and χ-phase formation and nitride precipitation) or plastic deformation at room temperature [austenite transformation into strain-induced martensite (SIM)]. These secondary phases noticeably affect the properties of DSS, and therefore are of huge industrial interest. In the present work, SIM formation was investigated in a 2101 lean DSS. The material was subjected to cold rolling at various degrees of deformation (from 10 to 80% thickness reduction) and the microstructure developed after plastic deformation was investigated by electron backscattered diffraction, X-ray diffraction measurements, and hardness and magnetic tests. It was observed that SIM formed as a consequence of deformations higher than ~20% and residual austenite was still observed at 80% of thickness reduction. Furthermore, a direct relationship was found between microstructure and magnetic properties.

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Katemi, Richard J., and Jeremy Epp. "Influence of Tempering and Cryogenic Treatment on Retained Austenite and Residual Stresses in Carbonitrided 18CrNiMo7-6 Low Alloy Steel." Tanzania Journal of Engineering and Technology 38, no. 1 (June 30, 2019): 71–82. http://dx.doi.org/10.52339/tjet.v38i1.497.

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This work investigated the influence of tempering conditions coupled with cryogenic treatment on thermal stabilization of retained austenite and residual stress distributions in carbonitrided 18CrNiMo76 low alloy steel samples. The carbonitriding conditions were set to enable attaining surface carbon and nitrogen content of 0.87 and 0.34 mass.-percent respectively. After carbonitriding, some of the samples were subjected to varying tempering conditions followed by cryogenic treatment at -120 °C using nitrogen gas. Analysis of both retained austenite and residual stresses was conducted using X-ray diffraction. In the as-quenched state, carbonitrided samples contained 52 mass.-percent. Samples that were directly subjected to the cryogenic treatment after quenching retained only about 20 mass.-percent of austenite. Samples subjected to variant tempering conditions coupled with cryogenic treatment retained at least 30 masses.-percent of austenite. A thermal stabilization of retained austenite which increases with increasing temperature was identified. On tempering at 240°C for 14 hours retained austenite becomes unstable and decomposes to bainite leading to the low initial amount of retained austenite before cryogenic treatment. It can be concluded that the tempering process coupled with cryogenic treatment leads to an increasing hardness, to higher compressive residual stresses as well as to a shift of the location of maximum compressive residual stress toward the surface.

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Hajavifard, Ramin, Fawad Maqbool, Anke Schmiedt-Kalenborn, Johannes Buhl, Markus Bambach, and Frank Walther. "Integrated Forming and Surface Engineering of Disc Springs by Inducing Residual Stresses by Incremental Sheet Forming." Materials 12, no. 10 (May 20, 2019): 1646. http://dx.doi.org/10.3390/ma12101646.

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Disc springs are conical annular discs, which are characterized by a high spring force with a small spring travel and good space utilization. In operation, they must meet high demands on the stability of the spring characteristic and the fatigue strength. Under loading, tensile stresses occur which limit the possible applications of disc springs. Compressive stresses can be generated in the stressed areas by means of shot-peening in order to extend the operating limits for a given yield and fatigue strength. Since the spring geometry and characteristics change during shot-peening, the design of the shot-peening treatment is iterative and cumbersome. The present research proposes an incremental forming process for forming and integrated targeted adjustment of residual stresses in disc springs from metastable austenitic stainless steel (MASS), to achieve improved spring properties and high cyclic strength. The main mechanism of residual stress generation is the transformation of metastable austenite into martensite under the action of the forming tool. Different experimental characterization techniques like the hole drilling method, X-ray diffraction, disc compression tests, optical microscopy and cyclic tests are used to correlate the residual stresses and disc spring properties. A numerical model is developed for simulating the martensite transformation in disc springs manufacturing. The results prove that incremental forming enables process-integrated engineering of the desired compressive residual stresses, entailing a higher spring force of metastable austenitic disc springs in comparison to conventional disc springs. Due to martensite formation, the generated residual stresses are stable under cyclic loading, which is not the case for conventionally manufactured springs.

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Clark, Andrew, Randy J. Bowers, and Derek O. Northwood. "Heat Treatment Effects on Distortion, Residual Stress, and Retained Austenite in Carburized 4320 Steel." Materials Science Forum 783-786 (May 2014): 692–97. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.692.

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The effects of heat treatment on distortion, residual stress, and retained austenite were compared for case-carburized 4320 steel, in both the austempered and quench-and-tempered condition. Navy C-ring samples were used to quantify both size and shape distortions, as well as residual stress. The austempering heat treatment produced less distortion and a higher surface residual stress. Both hoop and axial stresses were measured; the difference between them was less than seven percent in all cases. Depth profiles were obtained for residual stress and retained austenite from representative C-ring samples for the austempered and quench-and-tempered heat treatment conditions. Austempering maintained a compressive residual stress to greater depths than quench-and-tempering. Quench-and-tempering also resulted in lower retained austenite amounts immediately beneath the surface. However, for both heat treatments, the retained austenite content was approximately one percent at depths greater than 0.5 mm.

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Franceschi, Mattia, Luca Pezzato, Alessio Giorgio Settimi, Claudio Gennari, Mirko Pigato, Marina Polyakova, Dmitry Konstantinov, Katya Brunelli, and Manuele Dabalà. "Effect of Different Austempering Heat Treatments on Corrosion Properties of High Silicon Steel." Materials 14, no. 2 (January 8, 2021): 288. http://dx.doi.org/10.3390/ma14020288.

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A novel high silicon austempered (AHS) steel has been studied in this work. The effect of different austenitizing temperatures, in full austenitic and biphasic regime, on the final microstructure was investigated. Specimens were austenitized at 780 °C, 830 °C, 850 °C and 900 °C for 30 min and held isothermally at 350 °C for 30 min. A second heat treatment route was performed which consisted of austenitizing at 900 °C for 30 min and austempering at 300 °C, 350 °C and 400 °C for 30 min. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been used to evaluate the microstructural evolution. These techniques revealed that the microstructures were composed of carbide-free bainite, ferrite, martensite and retained austenite (RA) in different volume fractions (Vγ). An aqueous borate buffer solution with 0.3 M H3BO3 and 0.075 M Na2B4O7∂10H2O (pH = 8.4) was used for corrosion tests in order to evaluate the influence of the different volume fractions of retained austenite on the corrosion properties of the specimens. The results showed that when increasing the austenitization temperatures, the volume fractions of retained austenite reached a maximum value at 850 °C, and decrease at higher temperatures. The corrosion properties were investigated after 30 min and 24 h immersion by means of potentiodynamic polarization (after 30 min) and electrochemical impedance spectroscopy (after both 30 min and 24 h) tests. The corrosion resistance of the samples increased with increases in the volume fraction of retained austenite due to lower amounts of residual stresses.

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Franceschi, Mattia, Luca Pezzato, Alessio Giorgio Settimi, Claudio Gennari, Mirko Pigato, Marina Polyakova, Dmitry Konstantinov, Katya Brunelli, and Manuele Dabalà. "Effect of Different Austempering Heat Treatments on Corrosion Properties of High Silicon Steel." Materials 14, no. 2 (January 8, 2021): 288. http://dx.doi.org/10.3390/ma14020288.

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A novel high silicon austempered (AHS) steel has been studied in this work. The effect of different austenitizing temperatures, in full austenitic and biphasic regime, on the final microstructure was investigated. Specimens were austenitized at 780 °C, 830 °C, 850 °C and 900 °C for 30 min and held isothermally at 350 °C for 30 min. A second heat treatment route was performed which consisted of austenitizing at 900 °C for 30 min and austempering at 300 °C, 350 °C and 400 °C for 30 min. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been used to evaluate the microstructural evolution. These techniques revealed that the microstructures were composed of carbide-free bainite, ferrite, martensite and retained austenite (RA) in different volume fractions (Vγ). An aqueous borate buffer solution with 0.3 M H3BO3 and 0.075 M Na2B4O7∂10H2O (pH = 8.4) was used for corrosion tests in order to evaluate the influence of the different volume fractions of retained austenite on the corrosion properties of the specimens. The results showed that when increasing the austenitization temperatures, the volume fractions of retained austenite reached a maximum value at 850 °C, and decrease at higher temperatures. The corrosion properties were investigated after 30 min and 24 h immersion by means of potentiodynamic polarization (after 30 min) and electrochemical impedance spectroscopy (after both 30 min and 24 h) tests. The corrosion resistance of the samples increased with increases in the volume fraction of retained austenite due to lower amounts of residual stresses.

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25

Sukhikh, A. A., V. B. Dementiev, and T. M. Makhneva. "Properties of Austenite in Maraging Steel." Solid State Phenomena 284 (October 2018): 386–91. http://dx.doi.org/10.4028/www.scientific.net/ssp.284.386.

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The reasons of high strength of residual and reverted austenite in the maraging steel H18K9M5T are discussed. It has been shown that the high value of the residual austenite yield strength is due to the dispersity of its crystals and phase hardening; a significant increase in the strength properties of the reverted austenite is caused by the presence of intermetallide particles with high dispersity in it.

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26

Liu, H. S., M. H. Wang, X. Y. Ge, and H. S. Luo. "Effects of Different Heat Treatments on Transformation of Residual Austenite in Bearing Steel." Applied Mechanics and Materials 670-671 (October 2014): 56–60. http://dx.doi.org/10.4028/www.scientific.net/amm.670-671.56.

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The effect of heat treatment on transformation of residual austenite in bearing steel is studied, by adding the cryogenic treatment into the normal heat treatment process. The results indicate that the residual austenite content is decreased and the hardness is improved obviously, when putting the cryogenic treatment at -70°C or lower directly behind the quenching process. While when the tempering is added between quench and cryogenic treatment, the temperature of cryogenic treatment must be much lower than -70°C to offset the thermal stability of residual austenite, which is given by tempering.

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27

Djebaïli, H. "Comportement au revenu d'un acier du type Z80CDSV8.2.1.1 pour cylindres de laminoirs à chaud." Matériaux & Techniques 84 (1996): 3–12. http://dx.doi.org/10.1051/mattech/199684060003s.

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Transformations in Cr-Mo-Si steels with a specific addition of Vanadium have been characterized precisely as well as their effect on the hardness of the materials. A preliminary treatment in the austenitic field leads to a limited enrichment of the matrix as well as temperature is less than 1050°C : only M3C and M23C6 carbides may then be dissolved. On the contrary, the dissolution of M7C3 and MC carbides is observed over 1100°C but is only partial even after treatment at 1150°C. After quenching from three distinct temperatures (1050-1100 and 1150°C), the microstructure consists of martensite, residual austenite and primary carbides (mainly M7C3 and MC type) ; different tempering treatments have been performed (isochronal, isothermal or on continuous heating) using various physical methods (dilatometry, DTA and magnetic measurements, TEM observations and hot hardness testing). According to the maximum θR temperature reached, the following structural evolutions were observed :•ε carbide precipitates at θR < 250° C in the a’ matrix, then M3C carbide forms between 250 and 350°C which transforms in M7C3 carbide from 450 to 500°C. At the same time (300- 500°C) a secondary hardening occurs linked to the formation of very fine V4C3 carbides : a progressive increase in hot hardness is observed while holding isothermally at 300-450°C.•From 450 to 600°C, the residual austenite is destabilized owing to the precipitation of small carbides in α'/γ interfaces and may be transformed on cooling either in bainite or secondary martensite. On the other hand that impoverished austenite may be transformed in (α + carbides) between 600-700°C. Besides in the same temperature range, M6C and M23C6 may be formed at the expense of fine M7C3 carbides previously formed.

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Van Wijk, S., Manuel François, E. Sura, and M. Frabolot. "Retained Austenite and Residual Stress Evolution in Carbonitrided Shot-Peened Steel." Materials Science Forum 681 (March 2011): 374–80. http://dx.doi.org/10.4028/www.scientific.net/msf.681.374.

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Carbonitriding followed by shot peening is an important industrial process to improve the mechanical properties of components, especially by producing compressive residual stresses. In addition, a high hardness and strength produced by this process enhances the surface properties and leads also a high resistance to fatigue. In this study, shot peening with different parameters have been employed to treat the carbonitrided specimens. The measurements of residual stress and residual austenite were performed by X-ray diffraction. It is shown, with a simple eigenstrain model, that residual austenite transformation under shot impact contributes to a significant fraction of residual stresses. When the material (750 HV) is peened with 800 HV shot, it represents about 50%, the remaining is due to plasticity. When it is peened with 640HV shot, 100% of residual stresses can be explained by austenite transformation.

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29

Wilson, Brent M., and Matthew G. Dick. "Development of a predictive life tool for tapered roller bearings using measured residual stress and retained austenite data." Powder Diffraction 23, no. 2 (June 2008): 118–20. http://dx.doi.org/10.1154/1.2912443.

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The development of a tool called the Service Load Factor (SLF) for railway tapered roller bearings using residual stress and retained austenite data is presented. Case-carburized tapered roller bearings used in the railroad industry are manufactured with a dual-phase microstructure that consists primarily of tempered martensite and retained austenite. The retained austenite phase is metastable, and will transform to martensite with sufficient thermal or mechanical energy during service. The increase in surface volume because of transformation, and the subsequent increase in compressive residual stress could indicate the onset of certain failure modes, including fatigue spalling. In addition, retained austenite transformation can lead to an increase in bore diameter, which could result in a loss of fit on the axle journal. Several bearing inner races with various service histories were measured with a Siemens X-ray diffractometer using chromium radiation. Results indicated that the transformation of retained austenite and resultant increase in compressive residual stress are interrelated with load and rolling cycles. Results indicate that the SLF is a useful tool that correlates well with current Association of American Railroads failure criteria.

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30

Filep, Adám, Márton Benke, and Valéria Mertinger. "Spatial Residual Stress Distribution in Multi-Phase Steel." Materials Science Forum 885 (February 2017): 135–40. http://dx.doi.org/10.4028/www.scientific.net/msf.885.135.

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Residual stress measurements were carried out on duplex steel samples using X-ray diffraction technique. Directional residual stress was investigated on the surface of the heat effected zone of joints. Spatial residual stress distribution were examined in the ferrite and austenite phases separately, using different radiation-ray source. The different mechanical properties of each phases were taken into account during the stress calculations. Noticeable stress gradient was observed between ferrite and austenite phases.

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31

FENG, QIANG, JIA SHE, YONG XIANG, XIANYUN WU, CHENGXI WANG, and CHUANHAI JIANG. "INFLUENCE OF ANNEALING ON THE DEPTH MICROSTRUCTURE OF THE SHOT PEENED DUPLEX STAINLESS STEEL AT ELEVATED TEMPERATURE." Surface Review and Letters 25, no. 02 (February 2018): 1850059. http://dx.doi.org/10.1142/s0218625x18500592.

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The depth profiles of residual stresses and lattice parameters in the surface layers of shot peened duplex stainless steel at elevated temperature were investigated utilizing X-ray diffraction analysis. At each deformation depth, residual stress distributions in both ferrite and austenite were studied by X-ray diffraction stress analysis which is performed on the basis of the sin[Formula: see text] method and the lattice parameters were explored by Rietveld method. The results reveal that difference changes of depth residual compressive stress profiles between ferrite and austenite under the same annealing condition are resulted from the diverse coefficient of thermal expansion, dislocation density, etc. for different phases in duplex stainless steel. The relaxations of depth residual stresses in austenite are more obvious than those in ferrite. The lattice parameters decrease in the surface layer with the extending of annealing time, however, they increase along the depth after annealing for 16[Formula: see text]min. The change of the depth lattice parameters can be ascribed to both thermal expansion and the relaxation of residual stress. The different changes of microstructure at elevated temperature between ferrite and austenite are discussed.

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32

Christiansen, T. L., T. S. Hummelshøj, and M. A. J. Somers. "Expanded austenite, crystallography and residual stress." Surface Engineering 26, no. 4 (May 2010): 242–47. http://dx.doi.org/10.1179/026708410x12506870724316.

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33

Narkevich, Natalia, Yevgeny Deryugin, and Yury Mironov. "Effect of the γ→ε Phase Transition on Transformation-Induced Plasticity (TRIP) of Nickel-Free High Nitrogen Steel at Low Temperatures." Metals 11, no. 5 (April 26, 2021): 710. http://dx.doi.org/10.3390/met11050710.

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The deformation behavior, mechanical properties, and microstructure of Fe-Cr-Mn-0.53%N austenitic stainless steel were studied at a temperature range of 77 up to 293 K. The dynamics of the steel elongation were non-monotonic with a maximum at 240–273 K, when peaks of both static atom displacements from their equilibrium positions in austenite and residual stresses in the tensile load direction were observed. The results of X-ray diffraction analysis confirmed that the only stress-induced γ→ε-martensite transformation occurred upon deformation (no traces of the γ→α′ one was found). In this case, the volume fraction of ε-martensite was about 2–3%. These transformation-induced plasticity (TRIP) patterns were discussed in terms of changes in the phase composition of steel as the root cause.

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34

Maisuradze, Mikhail V., Aleksandra A. Kuklina, and Dmitriy I. Lebedev. "Isothermal Heat Treatment of the Low-Carbon Martensitic Steel." Solid State Phenomena 316 (April 2021): 264–68. http://dx.doi.org/10.4028/www.scientific.net/ssp.316.264.

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A study of the low-carbon steel with high hardenability was carried out. The steel contained the following alloying elements, wt. %: C – 0.20; Cr – 2.0; Mn – 2.0; Si – 1.04 Ni – 1.0; Mo – 0.3. The quenching – partitioning treatment of the studied steel was implemented. The microstructure of the steel consisted of the tempered martensite laths, bainite and martensite-austenite regions. The amount of the residual austenite and the carbon concentration in the residual austenite were estimated. The possibility of the quenching – partitioning treatment of the carburized steel was shown.

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35

Пустовойт, В. Н., Ю. В. Долгачев, and В. П. Караваев. "Распад остаточного аустенита в стали У12 при обработке в магнитном поле." ТЕНДЕНЦИИ РАЗВИТИЯ НАУКИ И ОБРАЗОВАНИЯ 70, no. 2 (2021): 71–73. http://dx.doi.org/10.18411/lj-02-2021-57.

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In article the analysis of influence of magnetic field on process of disintegration of austenite at release of U12 steel is carried out. The influence of the magnetic field leads to an intensification of the decay process of residual austenite and more intense isolation of the carbide phase from austenite.

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36

Nguyen, Phuoc Quy Phong. "Research on Fabrication of TRIP Steel with High Durability." European Journal of Engineering Research and Science 4, no. 2 (February 22, 2019): 33–36. http://dx.doi.org/10.24018/ejers.2019.4.2.1141.

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Many weapons and mechanical parts such as bullet shells, jet engine covers, bulletproof armor shells operated in harsh conditions require durability when used and good flexibility when forming. Many countries have used steel with phase transition effects due to plastic deformation - TRIP effect (Transformation Induced Plasticity) to replace low carbon steel, high-strength low-alloy steel fabricating them. The paper presents research on the technology of metallurgy of a CMnSiAl steel grade from sponge iron materials and application of mechanical-thermal technology to create small particles and organize three phases: Ferrite, Bainite, residual Austenite to stabilize and increase plasticity. The results show that the impurity content is low, S% is less than 0.025%; magnitude of small ferrite particles below 20μm, ratio of residual austenitic fγ = 6.39%. Mechanical properties: durable limit σb on 590 MPa, yield limit σc over 390 MPa, ratio σb/σc> 1.5 and relative elongation δ50 over 28%. Research results for the prospect of applying this steel grade in the manufacture of some defense products, instead imported materials.

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37

Di Schino, Andrea, and Maria Richetta. "Effect of micro-alloying on quenching behaviour of steels for back-up rolls." Acta Metallurgica Slovaca 23, no. 2 (June 30, 2017): 105. http://dx.doi.org/10.12776/ams.v23i2.898.

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<p>The use of micro-alloyed steels for back-up rolls manufacturing gives the possibility to obtain advantages associated with the benefit of the application of micro-alloying elements and thermo-mechanical treatments. In this paper the effect of alloying elements has been evaluated aimed to improve steel hardenability and at the same time to reduce the fabrication cost. 3% Cr and 5% Cr steels are considered with a reduced Mo content. Analysis of alloying on hardenability is performed by means of metallurgical models and on laboratory scale. Results show a higher hardenability in the case of 5% Cr steels. Moreover, such family of steels also show a dependence on prior austenitic grain size. In both the steel families no warnings are detected in terms of residual austenite presence after quenching.</p>

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38

Borzabadi Farahani, E., B. Sobhani Aragh, and WJ Mansur. "Three-dimensional finite element modelling of welding residual stresses of medium carbon steel pipes with consideration of solid-state austenite-martensite transformation and post-weld heat treatment." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 233, no. 11 (May 19, 2019): 2352–64. http://dx.doi.org/10.1177/1464420719850205.

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In the present work, three-dimensional finite element modelling is presented to simulate welding of the medium carbon steel pipes by considering both the solid-state austenite-martensite transformation and the post-weld heat treatment. Thermo-elasto-plastic and metallurgical analyses are carried out by developing two user-defined subroutines: one for applying the heat flux and the another one for considering phase transformation effects on welding residual stresses. The applied heat flux is simulated by a double ellipsoid model. Furthermore, the effects of volumetric change due to the solid-state austenite-martensite transformation are taken into account. The results obtained have revealed that volumetric change owing to the solid-state austenite-martensite transformation has a significant effect on the magnitude and distribution of welding residual stresses. The main contribution of the present work is providing helpful knowledge about welding residual stresses evolution after and before the post-weld heat treatment by considering the solid-state austenite-martensite transformation. In addition to reference to the time–temperature–transformation diagram, this study can result in safe selection of post-weld heat treatment parameters, which not only prevents sensitization to stress corrosion cracking and intergranular corrosion but also provides enough and more importantly controlled relaxation of welding residual stresses.

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39

Gibmeier, Jens, Esther Obelode, Jens Altenkirch, Arne Kromm, and Thomas Kannengiesser. "Residual Stress in Steel Fusion Welds Joined Using Low Transformation Temperature (LTT) Filler Material." Materials Science Forum 768-769 (September 2013): 620–27. http://dx.doi.org/10.4028/www.scientific.net/msf.768-769.620.

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Welding residual stress is of major concern for structural integrity assessment in industrial components. Shear and volume strains resulting from the austenite-martensite-transformation affect the development of residual stress during welding. Controlling the phase transformation allows adjustment of the welding residual stress. Low transformation temperature (LTT) weld filler materials exhibiting reduced MS-temperatures allow postponing the phase transformation. The associated strain arising from the delayed transformation compensates for the thermal contraction strains and as such may reduce tensile or even introduce compressive residual stress. In this article we discuss the tri-axial residual stress distribution in 15 mm S690Q steel plates joined with LTT filler materials with 10 wt% Cr and a Ni-content that varies from 8 to 12 wt%. Using complementary synchrotron X-ray and neutron diffraction stress analysis the macroscopic residual stress was derived from the phase specific lattice strain and phase fraction of martensite and retained austenite, respectively. The local phase specific unstrained lattice parameters were determined using stress relieved combs. The investigation revealed increasing phase fraction of retained austenite with increasing Ni-content. Further, independent of the Ni-content in each weld in the fusion zone, significant compressive residual stresses were found in the longitudinal direction, which are balanced by tensile residual stresses in the heat affected zone (HAZ). In the weld transverse and normal direction the stress distribution is qualitatively similar but less in magnitude. The increased amount of retained austenite reduces the compressive stress arising from shear and volume strains during the delayed phase transformation and therefore no significant increase in compression was observed for decreasing MS-temperatures.

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40

Sueyoshi, Hitoshi, Nobuyuki Ishikawa, Hiroshige Inoue, Kazuo Hiraoka, Tadashi Kasuya, Ke An, and Harley Skorpenske. "Analysis of Retained Austenite and Residual Stress Distribution in Ni-Cr Type High Strength Steel Weld by Neutron Diffraction." Materials Science Forum 783-786 (May 2014): 2115–19. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.2115.

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Prevention of weld cracking is necessary for ensuring the reliability of high strength steel structures. Tensile residual stress in the weld metal is one of the major factors causing the weld cracking, therefore, it is important to clarify the residual stress distribution in the weld metal. Conventional stress measurement, the stress relief method using strain gauges and the X-ray diffraction technique, can only provide the stress information in the surface region of the steel weld. The neutron diffraction is the only non-destructive method that can measure the residual stress distribution inside the steel weld [1-3]. The neutron stress measurement was applied for the 980MPa class high strength steel weld and it was revealed that high level of tensile residual stress can affect the weld cracking to a significant degree [4-5]. Recently, it was reported that Ni-Cr type steel weld exhibit higher resistance to the weld cracking compared with conventional low alloy type weld. Increase of tensile residual stress is prevented by lower transformation temperature of the Ni-Cr type weld metal and retained austenite phase is dispersed in the martensite microstructure. It is considered that lower level of tensile residual stress and the existence of retained austenite may prevent hydrogen accumulation in the weld metal [6]. However, retained austenite and the residual stress conditions in the Ni-Cr type high strength steel weld is not well understood. In this study, neutron diffraction analysis was conducted on the Ni-Cr type steel weld joint with the tensile strength level of 980MPa in order to investigate the effect of the retained austenite and the residual stress distribution on the weld cracking.

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41

El-Shenawy, Eman, Hoda Refaiy, and Hoda Nasr El-Din. "Thermal Stability of Retained Austenite in Advanced TRIP Steel with Bainitic Ferrite Matrix for Automotive Industries." Materials Science Forum 1016 (January 2021): 429–34. http://dx.doi.org/10.4028/www.scientific.net/msf.1016.429.

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Multiphase steels consisting of retained austenite and martensite/bainite microstructures such as TRIP, low-temperature-bainite, and Q&P steels are attractive candidates for the new-generation of AHSS. These steels exhibit a remarkable combination of strength and toughness which is essential to meet the objective of weight reduction of engineering-components, while maintaining the compromise of tough-safety requirements. Such good mechanical properties are due to the enhanced work hardening rate caused by austenite-to-martensite transformation during deformation and the strengthening contribution of martensite/bainite. The retained austenite can thermally decompose into more thermodynamically stable phases as a consequence of temperature changes, which is referred to as the thermal stability of retained austenite. TRIP-aided steel is an effective candidate for automotive parts because of safety and weight reduction requirements. The strength–ductility balance of high strength steel sheets can be remarkably improved by using transformation induced plasticity behavior of retained austenite. In manufacturing hot rolled TRIP-aided sheet steels, austenite transforms into bainite during the coiling process. Because black hot coils cool slowly after the coiling process, they are exposed at about 350–450°C for a few hours or days. Therefore, the metastable residual austenite can be decomposed into other phases. This decomposition of residual austenite can produce serious deteriorate of mechanical properties in hot rolled TRIP-aided sheet steels. The present work identified the decomposition behavior and study the thermal stability of retained austenite in the TRIP-aided steel with bainitic/ferrite matrix depending on coiling temperatures and holding times by means of DSC and XRD analysis.

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42

Pigatti, Gabriel Mombrini, Viviane Azambuja Favre Nicolin, and Felipe Fardin Grillo. "Evaluating the impact of titanium or equivalent carbon on the hot ductility of medium carbon steels." Rem: Revista Escola de Minas 66, no. 4 (December 2013): 455–60. http://dx.doi.org/10.1590/s0370-44672013000400008.

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In this work were evaluated the titanium and carbon effects on the hot ductility of medium carbon steels. In order to achieve this, used were the thermomechanical simulator Gleeble® 3500, for the hot tensile tests, and Scanning Electron Microscope (SEM) to analyze the aspect of the fracture. Microstructure analysis was done by an optical microscope. Five types of steel were studied. Two of them contained 0.02% of titanium and the others contained only residual amounts of this element. The results indicated that the Ti/N ratio between 3 and 5 regards lower loss of ductility at temperatures between 700ºC and 800ºC and at these temperatures the fractures are non-ductile. Steels containing titanium also show lower austenitic grain size at temperatures near to the austenite to ferrite transformation (Ar3). Moreover, the low ductility temperature was found to be inversely proportional to the equivalent carbon content.

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43

Zhang, Baozhuo, and Marcus L. Young. "High-energy synchrotron X-ray diffraction measurements of simple bending of pseudoelastic NiTi shape memory alloy wires." Powder Diffraction 31, no. 2 (May 23, 2016): 104–9. http://dx.doi.org/10.1017/s0885715616000154.

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Many technological applications of austenitic shape memory alloys (SMAs) involve cyclical mechanical loading and unloading in order to take advantage of pseudoelasticity. In this paper, we investigated the effect of mechanical bending of pseudoelastic NiTi SMA wires using high-energy synchrotron radiation X-ray diffraction (SR-XRD). Differential scanning calorimetry was performed to identify the phase transformation temperatures. Scanning electron microscopy images show that micro-cracks in compressive regions of the wire propagate with increasing bend angle, while tensile regions tend not to exhibit crack propagation. SR-XRD patterns were analyzed to study the phase transformation and investigate micromechanical properties. By observing the various diffraction peaks such as the austenite (200) and the martensite (${\bar 1}12$), (${\bar 1}03$), (${\bar 1}11$), and (101) planes, intensities and residual strain values exhibit strong anisotropy, depending upon whether the sample is in compression or tension during bending.

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44

Stavrev, Dimitar, and Tsanka D. Dikova. "Structure Features of Martensite and Residual Austenite during Treatment with Concentrated Energy Fluxes." Advanced Materials Research 83-86 (December 2009): 889–95. http://dx.doi.org/10.4028/www.scientific.net/amr.83-86.889.

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The paper deals with the structure features of Fe-C alloys quenched by means of laser, electron beam and plasma arc. The martensite and residual austenite obtained are highly inhomogeneous. Their morphology and distribution depend both on the initial state before quenching and on the kinetics of the temperature changes. Four different structures of martensite are observed – package, lamellar isothermal, lamellar thermo-kinetic and “feathery nest-like”. The new martensite structure observed, called by us “feathery nest-like”, is a result of explosive austenite-martensite transformation in pearlitic irons. It differs from the classic modification in its specific morphology. Low-carbon package martensite occupies the regions of the former ferrite grains. Its hardness reaches 1050-1150 HV0.1. In the regions of microstructure with increased carbon concentration lamellar martensite is observed. The residual austenite is with different proportion in relation to the martensite. In particular regions its quantity could reach 100%. It is characterized by a high quantity of imperfections and high mechanical properties. Its hardness reaches 450-500 HV0.1. The higher the power density and the lower the energy density of the concentrated energy flux, the higher the residual austenite quantity.

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45

Millot, R., P. Archambault, E. Gautier, J. P. Houin, A. Badard, J. Bellus, C. Hunter, Y. Desalos, and F. Ruckstuhl. "Transformation of residual austenite under thermomechanical variations." Le Journal de Physique IV 09, PR9 (September 1999): Pr9–361—Pr9–370. http://dx.doi.org/10.1051/jp4:1999937.

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46

Andreev, Yu G. "Residual austenite in martensitically aging H18K9M5T steel." Steel in Translation 37, no. 9 (September 2007): 743–49. http://dx.doi.org/10.3103/s0967091207090069.

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47

Basu, Ritwik, Lokendra Jain, Bikas Maji, Madangopal Krishnan, Karri V. Mani Krishna, Indradev Samajdar, and Prita Pant. "Microstructural Irreversibilities under Thermal Cycling in Ni-Ti-Fe Shape Memory Alloys." Materials Science Forum 702-703 (December 2011): 888–91. http://dx.doi.org/10.4028/www.scientific.net/msf.702-703.888.

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The thermal cycling (quenching in liquid nitrogen and reverting back to room temperature: austenite martensite reversible transformation) response of Ni-Ti-Fe shape memory alloys has been investigated. It was clearly noted that residual deformation, estimated in terms of noticeable differences in austenite grain size, depend on the relative clustering of fine grains. During repeated thermal cycling, the residual deformation, in-grain misorientation developments and retained martensite content scaled together: bringing out a clear picture of microstructural irreversibility.

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48

Skrzypek, S. J., M. Goły, Wiktoria Ratuszek, and Mieczyslaw Kowalski. "Non-Destructive Quantitative Phase and Residual Stress Analysis Versus Depth Using Grazing X-Ray Diffraction." Solid State Phenomena 130 (December 2007): 47–52. http://dx.doi.org/10.4028/www.scientific.net/ssp.130.47.

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The non-destructive structure characterisation of surface layers for various kinds of ball bearings can be a powerful method in surface characterization and in quality control. The ball bearings were made of 100Cr6 steel and they were superfinished and mechanically burnished. An application of classical X-ray diffraction sin2ψ method and classical Bragg-Brentano diffraction geometry in these kinds of surface examinations make some problems in term of X-ray real depth of penetration. An application of methods based on grazing angle X-ray diffraction geometry, made possible to get real value of residual macro-stresses, retained austenite and additionally could be suitable in estimation of their gradient-like distribution versus depth under surface. An application of this geometry to X-ray diffraction phase analysis enabled to get phase contents versus thickness under surface in non-destructive way as well. The results are not infected by gradient-like distribution. The X-ray quantitative phase analysis was used to establish volume fraction of transformed retained austenite. Theoretical calculation of residual macro-stresses due to volume fraction of transformed austenite in ball bearings and following measurements of residual stresses were curried out as well. The mechanical burnishing of ball bearings caused big compressive residual stresses about – 1000 MPa and phase transformation of austenite in thin surface layer. These factors can influence on properties of following exploitation and durability.

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Hu, Jun, Wen Quan Cao, Jie Shi, and Han Dong. "Study on the Mechanical Stability of Retained Austenite in Cold-Rolled Medium-Mn Steel." Advanced Materials Research 936 (June 2014): 1283–89. http://dx.doi.org/10.4028/www.scientific.net/amr.936.1283.

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The mechanical stability of the retained austenite in the cold-rolled medium-Mn steel was studied. Tensile tests were carried out to measure the mechanical properties of the annealed steel. Scanning electron microscopy was applied to characterize the microstructure evolution during the tensile process; X-ray diffraction analysis was used to determine the residual austenite content in the deformed steel. It was found that the volume fraction of retained austenite gradually decreases with strain .The value of the stability coefficient of retained austenite k was small in the test steel, which indicated high mechanical stability of retained austenite. Due to TRIP effect, the high mechanical stability of the retained austenite strongly delays the onset of necking, which resulted in good comprehensive mechanical properties with ultrahigh strength and plasticity.

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van de Putte, Tom, Zinedine Zermout, Didier Loison, Serge Claessens, and Jan Penning. "Selective Oxidation during the Austenitic Annealing of a CMnSi Steel." Advanced Materials Research 15-17 (February 2006): 129–34. http://dx.doi.org/10.4028/www.scientific.net/amr.15-17.129.

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High strength multiphase CMnSi steel is increasingly used in passenger cars. Si and Mn alloying levels are typically in the range of 1-2% in mass. While Si improves the mechanical properties, it considerably deteriorates the galvanisability of steel. Residual water vapour in the reducing gas atmosphere during the intercritical or austenitic annealing results in the selective oxidation of Si and Mn at the steel surface. Besides Mn and Si, C is oxidized as well at the steel surface, leading to the formation of CO gas and decarburisation of the steel surface. This decarburisation has a major influence on the phase composition in the steel surface region: it shifts the ferrite to austenite transformation to higher annealing temperatures, leading to differences in surface and bulk microstructure. The phase composition influences the solubility and diffusivity of all alloying elements near the surface. The evolution with temperature of the selective oxidation at the steel surface has been studied by interrupted annealing in a protective atmosphere containing residual water vapour. The influence of the annealing temperature on the selective oxidation of Mn and Si is characterized by XPS (X-ray Photo-electron Spectroscopy) analysis.

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Journal articles on the topic 'Austenite residua'

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