To see the other types of publications on this topic, follow the link: Austenite formation.
Journal articles on the topic 'Austenite formation'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Austenite formation.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Ravi Kumar, B. "Progress of Recrystallisation in Cold Rolled Austenitic Stainless Steel during Cyclic Thermal Process." Materials Science Forum 702-703 (December 2011): 627–30. http://dx.doi.org/10.4028/www.scientific.net/msf.702-703.627.
Full textAbstract:
The present study aims to understand the evolution of microstructure leading to nano/ultrafine grain formation during cyclic thermal process. A commercial grade of AISI 304L austenitic SS was cold rolled which resulted in a creation of a dual microstructure having strain induced martensite (43%) and heavily deformed retained austenite. The dual phase microstructure was subjected to cyclic thermal annealing process at 825 °C. The events occurring in; a) retained austenite and b) reverted austenite formed by phase reversion of strain induced martensite, during annealing treatment, were studied by the Electron backscattered diffraction (EBSD). The study revealed recrystallisation process of the two austenite grains, which resulted into ultrafine grain formation during cyclic thermal process.
2
Ryś, Janusz, and Wiktoria Ratuszek. "Rolling Texture Formation in Super-Duplex Stainless Steel." Solid State Phenomena 163 (June 2010): 145–50. http://dx.doi.org/10.4028/www.scientific.net/ssp.163.145.
Full textAbstract:
The present research is a part of project which concerns a deformation behavior of duplex type ferritic-austenitic stainless steels. This paper focuses on the examination of ferrite and austenite textures formed upon thermo-mechanical treatment and deformation textures developed during cold-rolling of super-duplex stainless steel sheet. The character and stability of the textures observed in both phases over a wide deformation range are the result of two-phase morphology formed upon hot- and subsequent cold-rolling. The specific band-like morphology of the ferrite-austenite structure creates different conditions for plastic deformation due to the interaction of both phases and considerably constrained lattice rotations. That is why the processes governing the texture formation in duplex steels are supposed to change in comparison to single phase steels affecting final rolling textures of ferrite and austenite.
3
Savran, V. I., Y. van Leeuwen, Dave N. Hanlon, and Jilt Sietsma. "Austenite Formation in C35 and C45 Alloys." Materials Science Forum 539-543 (March 2007): 4637–42. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.4637.
Full textAbstract:
The first step in the heat-treatment processes for a vast majority of commercial steels is austenitization. There is much less research put in this field comparing to the cooling transformation, but the interest is continuously increasing especially in view of the development of TRIP and Dual-phase steels. The microstructural evolution during continuous heating experiments has been studied for a series of C-Mn steels with carbon contents in the range 0.35-0.45 wt. % using optical and scanning electron (SEM) microscopy. It is shown that the formation of the austenitic phase is possible in pearlitic as well as in ferritic regions, although in the former it proceeds at a much faster rate due to the shorter diffusion distances. Thus a considerable overlap in time of the ferriteto- austenite and the pearlite-to-austenite transformations is likely to occur. Another observation that was made during the experiments is that depending on the heating rate, the pearlite-to-austenite transformation can proceed in either one or two steps. At low heating rates (0.05 °C/s) ferrite and cementite plates transform simultaneously. At higher heating rates (20 °C/s) it is a two-step process: first ferrite transforms to austenite within pearlite grains and then the dissolution of the cementite lamellae takes place.
4
Odnobokova, Marina, Andrey Belyakov, Alla Kipelova, and Rustam Kaibyshev. "Formation of Ultrafine-Grained Structures in 304L and 316L Stainless Steels by Recrystallization and Reverse Phase Transformation." Materials Science Forum 838-839 (January 2016): 410–15. http://dx.doi.org/10.4028/www.scientific.net/msf.838-839.410.
Full textAbstract:
The microstructure evolution and mechanical properties of 316L and 304L austenitic stainless steels subjected to large strain cold bar rolling and subsequent annealing were studied. The cold working was accompanied by mechanical twinning and strain-induced martensitic transformation. The latter was readily developed in 304L stainless steel. The uniform microstructures consisting of elongated austenite and martensite nanocrystallites evolved at large total strains, resulting in tensile strength above 2000 MPa in the both steels. The subsequent annealing at temperatures above 700°C was accompanied by the martensite-austenite reversion followed by recrystallization, leading to ultrafine grained austenite.
5
Cizek, Pavel. "Microstructure Evolution and Softening Processes in Hot Deformed Austenitic and Duplex Stainless Steels." Materials Science Forum 753 (March 2013): 66–71. http://dx.doi.org/10.4028/www.scientific.net/msf.753.66.
Full textAbstract:
The microstructure evolution and softening processes occurring in 22Cr-19Ni-3Mo austenitic and 21Cr-10Ni-3Mo duplex stainless steels deformed in torsion at 900 and 1200 °C were studied in the present work. Austenite was observed to soften in both steels via dynamic recovery (DRV) and dynamic recrystallisation (DRX) for the low and high deformation temperatures, respectively. At 900 °C, an “organised”, self-screening austenite deformation substructure largely comprising microbands, locally accompanied by micro-shear bands, was formed. By contrast, a “random”, accommodating austenite deformation substructure composed of equiaxed subgrains formed at 1200 °C. In the single-phase steel, DRX of austenite largely occurred through strain-induced grain boundary migration accompanied by (multiple) twinning. In the duplex steel, this softening mechanism was complemented by the formation of DRX grains through subgrain growth in the austenite/ferrite interface regions and by large-scale subgrain coalescence. At 900 °C, the duplex steel displayed limited stress-assisted phase transformations between austenite and ferrite, characterised by the dissolution of the primary austenite, formation of Widmanstätten secondary austenite and gradual globularisation of the transformed regions with strain. The softening process within ferrite was classified as “extended DRV”, characterised by a continuous increase in misorientations across the sub-boundaries with strain, for both deformation temperatures.
6
Tkacz-Śmiech, Katarzyna, Bartek Wierzba, Bogdan Bożek, and M. Danielewski. "Nitrogen Diffusion and Stresses during Expanded Austenite Formation in Nitriding." Defect and Diffusion Forum 371 (February 2017): 49–58. http://dx.doi.org/10.4028/www.scientific.net/ddf.371.49.
Full textAbstract:
Low-temperature nitriding of austenitic stainless steels or chromium containing alloys can produce expanded austenite, known as S-phase, with combined improvement in wear and corrosion resistance. In the paper a critical review of various models for nitrogen diffusion during nitriding is presented. A special attention is paid to the expanded austenite growth. A new model based on bi-velocity method and including stresses is presented. Basic equations and boundary conditions are discussed. Composition dependent nitrogen diffusion coefficient is assumed. Numerical solutions are obtained for the growth of the S-phase layer in steel. The results are compared with previous experiment and calculations.
7
Werner, K. V., H. L. Che, M. K. Lei, T. L. Christiansen, and M. A. J. Somers. "Low Temperature Carburizing of Stainless Steels and the Development of Carbon Expanded Austenite*." HTM Journal of Heat Treatment and Materials 77, no. 1 (February 1, 2022): 3–15. http://dx.doi.org/10.1515/htm-2022-0001.
Full textAbstract:
Abstract Low-temperature carburizing dramatically enhances the inherently low wear resistance of austenitic stainless steels due to the formation of a carbon-supersaturated solid solution, i.e. expanded austenite. The formation of expanded austenite from low-temperature carburizing has been intensively investigated. However, the influence of chemical composition of the stainless steel on the carburizing response has not received the same interest. This contribution addresses the effect of the chemical composition on low-temperature carburizing in terms of carbon solubility, decomposition of expanded austenite upon exceeding the solubility limit and the elasto-plastic accommodation of the carbon-induced lattice expansion. The results demonstrate that the carbon solubility increases with an increasing Cr-equivalent and that higher Cr- and Ni-equivalents favor the formation of Cr-based M7C3 over Fe-based Hägg (M5C2) carbide.
8
Ravi Kumar, B., J. K. Sahu, and S. K. Das. "Influence of Annealing Process on Recrystallisation Behaviour of a Heavily Cold Rolled AISI 304L Stainless Steel on Ultrafine Grain Formation." Materials Science Forum 715-716 (April 2012): 334–39. http://dx.doi.org/10.4028/www.scientific.net/msf.715-716.334.
Full textAbstract:
AISI 304L austenitic stainless steel was cold rolled to 90% with and no inter-pass cooling to produced 89% and 43% of deformation induced martensite respectively. The cold rolled specimens were annealed by isothermal and cyclic thermal process. The microstructures of the cold rolled and annealed specimens were studied by the electron microscope. The observed microstructural changes were correlated with the reversion mechanism of martensite to austenite and strain heterogeneity of the microstructure. The results indicated possibility of ultrafine austenite grain formation by cyclic thermal process for austenitic stainless steels those do not readily undergo deformation induced martensite. Keywords: Austenitic stainless steel, Grain refinement, Cyclic thermal process, Ultrafine grain
9
Lopata, V., M. Chernovol, E. Solovuch, and O. Dudan. "Use of structural anomalies in steel gas-thermal coatings during increased wear-out." Problems of tribology 102, no. 4 (December 24, 2021): 61–67. http://dx.doi.org/10.31891/2079-1372-2021-102-4-61-67.
Full textAbstract:
The structure of gas-thermal coatings made of wire materials has been studied by determining the most efficient methods of controlling the process of structure formation to achieve the highest physical and mechanical properties of renewable surfaces of vehicle parts. The effect of formation of anomaly amount of residual austenite in sprayed steel coatings was established. Technologies of application of the “austenitic effect” is suggested here to increase a coating wear-resistance. It is determined that the main factors influencing the content of residual austenite in hardened steel are the cooling rate of steel, the concentration of alloying elements in the austenitic phase, as well as thermal stabilization of austenite during self-tempering. It is shown that to ensure the formation in the structure of sprayed coatings of alloy structural, tool and corrosion-resistant steels of metastable austenite, which has a low flow temperature of deformation gamma-alpha transformation, which corresponds to the operating temperatures of sliding friction units, it is necessary to achieve certain coating conditions. wire spraying, cooling rate of molten particles and the degree of their oxidation). One of the most probable reasons for the appearance of the "austenitic effect" in coatings is the heating of the surface layer to a temperature that promotes thermal stabilization of austenite, as well as saturation of melt droplets with alloying elements (primarily chromium) and impurities (carbon, nitrogen) in flames. The relatively low flight speed of molten steel particles and the high concentration of propane containing carbon in the combustion products contribute to the deep saturation of the melt droplets with carbon. It is likely that these circumstances are associated with a high content of residual austenite in the coatings obtained by gas-flame spraying. An additional factor that increases the resistance of austenite in the sprayed coating may be the saturation of the droplets of the melt with carbon during melting and spraying using a propane flame. The studies under discussion have suggested that both for the method of gas-flame spraying and for the method of electric arc spraying, there are modes and steels for spraying that allow the formation of large amounts of metastable austenite in coatings, which in the process of tribocoupling will turn into martensite.On the basis of the carried-out researches technologies of restoration of details of vehicles by drawing multipurpose coverings in which the choice of a method of heating of a wire at spraying is carried out depending on temperature of the beginning of martensitic transformation of a wire material are offered.
10
Cota Araujo, Mahira A., Jean-Marc Olive, Gilles Pecastaings, Ahmed Addad, Jérémie Bouquerel, and Jean-Bernard Vogt. "Compelling Evidence for the Role of Retained Austenite in the Formation of Low Cycle Fatigue Extrusions in a 9Ni Steel." Metals 13, no. 3 (March 8, 2023): 546. http://dx.doi.org/10.3390/met13030546.
Full textAbstract:
The 9Ni martensitic steels have a martensitic microstructure which contains retained austenite after solution heat treatment and water quenching. Under low cycle fatigue, extrusions formed at the surface of the material and were very close to martensite lath boundaries. The presence of retained austenite at martensite laths has been highly suspected to impact the cyclic plasticity. However, the nano-size of the austenitic phase makes it difficult to obtain clear evidence of its role. The paper focuses on the precise determination of these extrusions and the link with the retained austenite. The paper also emphasizes the innovative and promising use of magnetic force microscopy (MFM) to document cyclic plasticity of a 9Ni steel. It is shown that electron microscopies, even the most advanced ones, may be unsuccessful in reaching this goal, while magnetic force microscopy (MFM) overcame the difficulty. This technique has allowed imaging of both the extrusion and the retained austenite. These analyses confirm that the fatigue extrusions originated from a local displacement of martensite lath. The proposed mechanism, in which the retained austenitic film acts as a lubricant film or greasy film promoting a flowing of martensite along the interfaces, is unambiguously demonstrated.
11
Pinedo, Carlos Eduardo, and André Paulo Tschiptschin. "Low temperature plasma carburizing of AISI 316L austenitic stainless steel and AISI F51 duplex stainless steel." Rem: Revista Escola de Minas 66, no. 2 (June 2013): 209–14. http://dx.doi.org/10.1590/s0370-44672013000200011.
Full textAbstract:
In this work an austenitic AISI 316L and a duplex AISI F51 (EN 1.4462) stainless steel were DC-Plasma carburized at 480ºC, using CH4 as carbon carrier gas. For the austenitic AISI 316L stainless steel, low temperature plasma carburizing induced a strong carbon supersaturation in the austenitic lattice and the formation of carbon expanded austenite (γC) without any precipitation of carbides. The hardness of the carburized AISI 316L steel reached a maximum of 1000 HV due to ∼13 at% carbon supersaturation and expansion of the FCC lattice. For the duplex stainless steel AISI F51, the austenitic grains transformed to carbon expanded austenite (γC), the ferritic grains transformed to carbon expanded ferrite (αC) and M23C6 type carbides precipitated in the nitrided case. Hardness of the carburized case of the F51 duplex steel reached 1600 HV due to the combined effects of austenite and ferrite lattice expansion with a fine and dispersed precipitation of M23C6 carbides.
12
Militzer, Matthias, and Hamid Azizi-Alizamini. "Phase Field Modelling of Austenite Formation in Low Carbon Steels." Solid State Phenomena 172-174 (June 2011): 1050–59. http://dx.doi.org/10.4028/www.scientific.net/ssp.172-174.1050.
Full textAbstract:
There is renewed interest in the investigation of austenite formation due to the development and increased use of advanced high strength steels for automotive applications. Intercritical annealing is an essential processing step for cold rolled and coated steel products with multi-phase microstructures. During intercritical annealing the initial ferrite-pearlite microstructure transforms partially to austenite. Models for the austenite formation are critical to predict the austenite fraction as a function of the thermal cycle thereby facilitating the design and control of robust processing paths. Modelling the austenite formation is challenging because of the morphological complexity of this transformation. Phase field models are a powerful tool to describe the evolution of microstructures with complex morphologies, e.g. formation of finger-type features during austenite formation. The present paper gives an overview of model approaches for the austenite formation. Phase field simulations are presented for two scenarios: (i) austenite formation from a fully pearlitic structure with a lamellar arrangement of carbide aggregates and (ii) austenite formation from ferrite-pearlite microstructures. Simulation results are compared with experimental observations for pearlitic steels. The challenges are delineated for the development of austenite formation models with predictive capabilities.
13
Fukumaru, T., T. Inoue, Toshihiro Tsuchiyama, and Setsuo Takaki. "Formation of Ultra Fine Grained Structure during Annealing of Heavily Drawn Metastable Austenitic Steel Wire." Materials Science Forum 558-559 (October 2007): 1309–12. http://dx.doi.org/10.4028/www.scientific.net/msf.558-559.1309.
Full textAbstract:
It is well known that the ultra grain refinement can be achieved by sever cold rolling, followed by reversion treatment in metastable austenitic stainless steel plate. In this study, the cold rolling was replaced by cold drawing. This procedure was applied to a metastable austenitic steel (Fe-16Cr-10Ni alloy) thin wire, and then the microstructure development during cold drawing and annealing was investigated. The austenite phase transformed to martensite during the drawing. Vickers hardness of the wire markedly increased with increasing the drawing strain. When the drawing strain reached about 4.5, the wire exhibited martensite single structure and had high hardness of Hv4.4GPa. Annealing of the heavily drawn wire at around 900K for 0.6ks leads to the formation of reversed austenite with the diffusional reversion mechanism. As a result, ultra fine-grained austenitic single structure with the grain size of about 0.6μm was obtained. It was also found that the wire has an excellent combination of a strength and ductility.
14
Bandi, Bharath, Joost Van Krevel, and Prakash Srirangam. "Interaction Between Ferrite Recrystallization and Austenite Formation in Dual-Phase Steel Manufacture." Metallurgical and Materials Transactions A 53, no. 4 (February 4, 2022): 1379–93. http://dx.doi.org/10.1007/s11661-022-06597-2.
Full textAbstract:
AbstractIn this publication, the effect of heating rate on microstructural evolution of manganese segregated cold reduced dual phase steels is systematically studied for different inter-critical temperatures and holding times. At slow heating rate, completion of ferrite recrystallization before austenite formation led to the preferential formation of austenite on the ferrite grain boundaries leading to a necklace austenite (now martensite) morphology. The slower austenite formation kinetics has been attributed to longer diffusion paths dictated by larger ferrite grain sizes. In medium heating rate condition, microstructure before austenite formation had partially recrystallized ferrite and partially spheroidized cementite. Rapid austenite growth occurred along the rolling direction in carbon-rich cementite regions and dislocation-rich recovered ferrite regions. The presence of partially recrystallized ferrite grains restricted the austenite growth in the normal direction and therefore enabled the formation of thin martensite bands parallel to the rolling direction. At fast heating rate, the microstructure before austenite formation predominately contained un-recrystallized ferrite and un-spheroidized cementite and therefore enabled faster austenite formation kinetics. Thicker martensite bands are formed at fast heating rates due to the absence of recrystallized grains, thereby, enabling the growth of austenite in all directions with a higher preference to the rolling direction.
15
Fonseca, Solange T., Amilton Sinatora, Antonio J. Ramirez, Domingos J. Minicucci, Conrado R. Afonso, and Paulo Roberto Mei. "Effects of Vanadium on the Continuous Cooling Transformation of 0.7 %C Steel for Railway Wheels." Defect and Diffusion Forum 367 (April 2016): 60–67. http://dx.doi.org/10.4028/www.scientific.net/ddf.367.60.
Full textAbstract:
To understand the effect of vanadium on the austenite decomposition of a 0.7 %C steel used in railway wheels the Continuous Cooling Transformation (CCT) diagrams were obtained and the microstructures analyzed with optical, SEM, TEM and XRD techniques. Vanadium refined the austenitic grain (12 and 6 μm for 7C and 7V, respectively), what can be explain by the presence of fine (10 nm in diameter) V4C3 precipitates, which restricts the austenitic grain growth. In addition, vanadium, in solid solution, reduced the pearlite interlamelar spacing (0.13 and 0.11 μm for 7C and 7V, respectively) by depressing the initial temperature pearlite formation (644 and 639 °C for 7C and 7V, respectively). He increased the ferrite volume fraction from 1 to 3 % at cooling rate of 1 oC/s, due the fact that vanadium is a ferrite stabilizer. Vanadium addition did not affect the initial temperature for martensite formation, but increased the hardenability with martensite formation at slower cooling rates (10 and 5 oC/s for 7C and 7V, respectively). For higher cooling rates (20 to 100 oC/s), the austenite transformation to martensite at room temperature was incomplete and all steels presented martensite and retained austenite, which volumetric fraction was near the same for both steels varying from 20 to 40 %.
16
Landesberger, Martin, Robert Koos, Michael Hofmann, Xiaohu Li, Torben Boll, Winfried Petry, and Wolfram Volk. "Phase Transition Kinetics in Austempered Ductile Iron (ADI) with Regard to Mo Content." Materials 13, no. 22 (November 21, 2020): 5266. http://dx.doi.org/10.3390/ma13225266.
Full textAbstract:
The phase transformation to ausferrite during austempered ductile iron (ADI) heat treatment can be significantly influenced by the alloying element Mo. Utilizing neutron diffraction, the phase transformation from austenite to ausferrite was monitored in-situ during the heat treatment. In addition to the phase volume fractions, the carbon enrichment of retained austenite was investigated. The results from neutron diffraction were compared to the macroscopic length change from dilatometer measurements. They show that the dilatometer data are only of limited use for the investigation of ausferrite formation. However, they allow deriving the time of maximum carbon accumulation in the retained austenite. In addition, the transformation of austenite during ausferritization was investigated using metallographic methods. Finally, the distribution of the alloying elements in the vicinity of the austenite/ferrite interface zone was shown by atom probe tomography (APT) measurements. C and Mn were enriched within the interface, while Si concentration was reduced. The Mo concentration in ferrite, interface and austentite stayed at the same level. The delay of austenite decay during Stage II reaction caused by Mo was studied in detail at 400 °C for the initial material as well as for 0.25 mass % and 0.50 mass % Mo additions.
17
Malet, Loic, Chad W. Sinclair, Pascal Jacques, and Stéphane Godet. "Grain Scale Analysis of Variant Selection during the Gamma-Epsilon-Alpha' Phase Transformation in Austenitic Steels." Solid State Phenomena 172-174 (June 2011): 84–89. http://dx.doi.org/10.4028/www.scientific.net/ssp.172-174.84.
Full textAbstract:
Austenitic steels can exhibit a complex transformation sequence during deformation. Indeed, the austenitic phase transforms first into bands of ε (HCP) martensite. This transformation is then followed by the formation of α’ (BCC) martensite. In this study, the crystallography of the transformation together with the occurrence of variant selection is studied at the scale of individual austenite grains. About ten prior austenite grains deformed at different strain levels in uniaxial tension were analysed by means of EBSD techniques. One of the classical approaches to predict the variant selection phenomenon is based on the calculation of the interaction energy between the macroscopic stress and the shape deformation associated with the formation of the product phase. The formation of the α’ variants was observed to lead to a very strong variant selection that cannot be fully explained by energetic criterion. It is suggested that the crystallography of the transformation sequence can account for the unexpected variants.
18
Brollo, Gabriela Lujan, and Paulo Roberto Mei. "Formation and reversion of strain induced martensite on Fe-Cr-Ni alloys." Rem: Revista Escola de Minas 66, no. 2 (June 2013): 221–25. http://dx.doi.org/10.1590/s0370-44672013000200013.
Full textAbstract:
Austenitic stainless steels represent a significant portion of the alloys used in the aeronautical, chemical, shipbuilding, food processing and biomechanical industries. They combine good mechanical properties with high corrosion resistance. When subjected to cold deformation, these steels exhibit a metastable phase called: strain induced martensite (ferromagnetic), whose formation increases mechanical strength and formability, allowing for a wide range of applications. Heated from room temperature, the strain induced martensite transforms to austenite (non-magnetic). It is easy to find information in literature about the strain induced martensite for 18Cr/8Ni austenitic steels, but there is no data for high nickel alloys like A286 (26Ni, 15Cr), Incoloy 800 (30-40 Ni, 21Cr) and Inconel (50Ni, 19Cr). Therefore, this study aimed to verify the formation of strain induced martensite after cold working in Fe-18Cr base alloys with the addition of up to 60 %Ni. The reversion of this phase to austenite after annealing up to 600 ºC was also studied. Optical microscopy, magnetic characterization tests, and x-ray diffraction were used to analyze the transformations.
19
Hu, Xiaodong, Lu Qin, Huanqing Wang, Lu Zhang, and Xuefang Xie. "Microstructure Formation and Its Effect on Mechanical Properties for Duplex Stainless Steel 2205 Plasma Arc Welded Joint." Metals 14, no. 1 (January 6, 2024): 68. http://dx.doi.org/10.3390/met14010068.
Full textAbstract:
The control of phase balance has always been a tough challenge for the welding of duplex stainless steel, which heavily restricts its optimal serving performance in engineering. The microstructure development and mechanical characteristics of SAF2205 plasma arc welded joints were thoroughly examined in this paper. It was proven that the phase balance can be well controlled by plasma arc welding, and the austenite content of the welded joints was about 60%. Despite successful phase control, there was still grain coarsening and distortion; i.e., at the center of the welded zone, the gain size was about eight times that of the base metal, and the austenite was mainly in the form of grain boundary austenite and intragranular austenite, while more Widmanstatten austenites were found in the heat-affected zone. In addition, a transition region between the heat affected zone and the center exhibited columnar ferritic grains. Furthermore, the plasticity and toughness of the welded joints were significantly decreased, especially the elongation in the longitudinal direction, which is about 10% lower than that of the base metal, and transversal tensile strength remained comparable to the base metal, with only a slight reduction in longitudinal tensile strength. Lastly, the formation mechanism of microstructure and its correlation with mechanical properties were revealed. This investigation offers valuable insights into the structural integrity of duplex stainless steel welded joints in engineering applications.
20
Ryś, J., and A. Zielińska-Lipiec. "Deformation of Ferrite-Austenite Banded Structure in Cold-Rolled Duplex Steel / Odkształcenie Pasmowej Struktury Ferrytu I Austenitu W Walcowanej Na Zimno Stali Duplex." Archives of Metallurgy and Materials 57, no. 4 (December 1, 2012): 1041–53. http://dx.doi.org/10.2478/v10172-012-0116-2.
Full textAbstract:
Duplex type ferritic-austenitic stainless steels develop a specific two-phase banded structure upon thermo-mechanical pre-treatment and subsequent cold-rolling. The band-like morphology of ferrite and austenite imposes different conditions on plastic deformation of both constituent phases in comparison to one-phase ferritic and austenitic steels. In the present research the ingot of a model ferritic-austenitic steel of duplex type, produced by laboratory melt, was subjected to preliminary thermo-mechanical treatment including forging and solution annealing. Afterwards cold-rolling was conducted over a wide deformation range. The investigations comprised examination of ferrite and austenite microstructures by means of optical and transmission electron microscopy and texture measurements after selected rolling reductions. The presented results indicate that deformation mechanisms operating within the bands of both constituent phases are essentially the same as compared to one-phase steels, however their appearance and contribution are changed upon deformation of two-phase banded structure. Different deformation behavior within ferrite-austenite bands in duplex steels, visible especially at higher strains, considerably affects microstructure evolution and in consequence texture formation in both phases.
21
Kubler, R., M. Berveiller, M. Cherkaoui, and K. Inal. "Transformation Textures in Unstable Austenitic Steel." Journal of Engineering Materials and Technology 125, no. 1 (December 31, 2002): 12–17. http://dx.doi.org/10.1115/1.1525249.
Full textAbstract:
During the martensitic transformation in elastic-plastic materials, the local transformation strain as well as the plastic flow inside austenite are strongly related with the crystallographic orientation of the austenitic lattice. Two mechanisms involved in these materials, i.e., plasticity by dislocation motion and martensitic phase formation are coupled through kinematical constraints so that the lattice spin of the austenitic grains is different from the one due to classical slip. In this work, the lattice spin ω˙eA of the austenitic grains is related with the slip rate on the slip systems of the two phases, γ˙A and γ˙M, the evolution of the martensite volume fraction f˙ and the overall rotation rate Ω˙ of the grains. This new relation is integrated in a micromechanical model developed for unstable austenite in order to predict the evolution of the austenite texture during TRansformation Induced Plasticity (TRIP). Results for the evolution of the lattice orientation during martensitic transformation are compared with experimental data obtained by X-ray diffraction on a 304 AISI steel.
22
Berezovskaya, Vera V., Eugeny A. Merkushkin, and Yu A. Raskovalova. "Structure Formation in High-Nitrogen Steel during Heat Treatment." Solid State Phenomena 284 (October 2018): 447–54. http://dx.doi.org/10.4028/www.scientific.net/ssp.284.447.
Full textAbstract:
Steel 06Cr18Mn19Mo2N (P900N + Mo) was chosen to study the phase composition and structural transformations occurring in high-nitrogen nickel-free austenitic steels as a result of heat treatments to which they are exposed during production or operation. The methods of light and electron microscopy, X-ray diffraction and dilatometric analysis were used in the work. The heat treatment scheme included hot plastic deformation, quenching and aging over a wide temperature range. It is shown that after the hot plastic deformation and quenching from 1050-1150 °С, and also after quenching with subsequent aging at 300 and 500 °С, the structure consists of austenite and isostructural matrix of nanoscale nitrides CrN. Thermal aging of steel at 700-750 °C causes the formation of Mo2N nitrides along the grain boundaries, and at 800 °C the decomposition of austenite is accompanied by a discontinuous reaction γγdepleted + σ with the formation of the χ-phase at prolonged exposures.
23
Pyshmintsev, I. Yu, S. M. Bityukov, and A. A. Gusev. "Effect of retained austenite on mechanical properties of steel with 15 % Cr." Izvestiya. Ferrous Metallurgy 66, no. 5 (November 11, 2023): 571–79. http://dx.doi.org/10.17073/0368-0797-2023-5-571-579.
Full textAbstract:
The paper considers the study of influence of retained austenite on the mechanical properties of steel of the austenite-martensitic class based on 15 % Cr after various heat treatment. Significant amount of retained austenite remains in the steel microstructure after quenching and subsequent tempering or heating in the intercritical temperature range that makes difficult to achieve a high yield strength. Destabilization of retained austenite with subsequent transformation into newly formed martensite is provided by multi-stage heat treatment which includes quenching, heating in the intercritical temperature range or above the AC3 point and final tempering. It was established that retained austenite remains in the microstructure of two-phase steel and has the form of blocks and thin layers located in the inter-lath space. Tensile testing of steel based on 15 % Cr showed that multi-stage heat treatment provides a high-strength condition corresponding to strength groups Q125 and Q135. A comparative analysis of deformation behavior of semi-austenitic steel in various states indicates that the beginning of the martensitic transformation after the final tempering shifts into the elastic region during tension and leads to the formation of stress-assisted martensite. It was determined that block-shaped retained austenite in steel with 15 % Cr predominantly undergoes martensitic transformation during tensile and impact tests at a subzero temperature. This is supposed to be the reason for the noticeably lower impact toughness of semi-austenitic steel with 15 % Cr compared to martensitic steel with 13 % Cr at equal strength.
24
Martin, Stefan, Christiane Ullrich, Daniel Šimek, Ulrich Martin, and David Rafaja. "Stacking fault model of ∊-martensite and itsDIFFaXimplementation." Journal of Applied Crystallography 44, no. 4 (June 28, 2011): 779–87. http://dx.doi.org/10.1107/s0021889811019558.
Full textAbstract:
Plastic deformation of highly alloyed austenitic transformation-induced plasticity (TRIP) steels with low stacking fault energy leads typically to the formation of ∊-martensite within the original austenite. The ∊-martensite is often described as a phase having a hexagonal close-packed crystal structure. In this contribution, an alternative structure model is presented that describes ∊-martensite embedded in the austenitic matrixviaclustering of stacking faults in austenite. The applicability of the model was tested on experimental X-ray diffraction data measured on a CrMnNi TRIP steel after 15% compression. The model of clustered stacking faults was implemented in theDIFFaXroutine; the faulted austenite and ∊-martensite were represented by different stacking fault arrangements. The probabilities of the respective stacking fault arrangements were obtained from fitting the simulated X-ray diffraction patterns to the experimental data. The reliability of the model was proven by scanning and transmission electron microscopy. For visualization of the clusters of stacking faults, the scanning electron microscopy employed electron channelling contrast imaging and electron backscatter diffraction.
25
Yang, Yue Hui, Jing Li, Shao Qiang Yuan, and Guo Li Liang. "Investigation on the Formation of Reversed Austenite in QT Treatment." Advanced Materials Research 1081 (December 2014): 219–23. http://dx.doi.org/10.4028/www.scientific.net/amr.1081.219.
Full textAbstract:
Microstructures of 9Ni steel quenched at different temperatures were obtained, and a simulated tempering at different temperature was implemented with the DIL850A dilatometer, then the effect of initial microstructure before tempering on the formation of reversed austenite was studied. Results show that the formation of reversed austenite during tempering becomes easier with the decrease of quenching temperature and the increasing of tempering temperature, but the stability may deteriorates with the rapid increasing of reversed austenite in content. Overall, the amount of reversed austenite mainly depends on the tempering temperature, and its formation rate is affected by the quenching temperature because refined quenching microstructure can promote the formation of reversed austenite observably.
26
Onuki, Yusuke, Kazuki Umemura, Kazuki Fujiwara, Yasuaki Tanaka, Toshiro Tomida, Kaori Kawano, and Shigeo Sato. "Microstructure Formation and Carbon Partitioning with Austenite Decomposition during Isothermal Heating Process in Fe-Si-Mn-C Steel Monitored by In Situ Time-of-Flight Neutron Diffraction." Metals 12, no. 6 (June 2, 2022): 957. http://dx.doi.org/10.3390/met12060957.
Full textAbstract:
Retained austenite is a key feature used to realize the transformation-induced plasticity in bainitic high strength steels. In this study, the authors focused on the formation of metastable austenite in Fe-0.61C-1.9Si-0.98Mn (mass%) during isothermal heating processes using in situ neutron diffraction techniques. Quantitative discussion of carbon partitioning processes is enabled by applying an in situ phase fraction analysis considering crystallographic textures, in addition to the carbon concentration estimation based on the lattice parameter of austenite. The carbon partitioning behavior is inhomogeneous, resulting in a bimodal carbon concentration distribution in austenite. The carbon enriched, high carbon austenite is stable during isothermal heating at 673 K and is retained even after cooling to room temperature. The remainder is low carbon austenite, which is gradually consumed by bainite transformation. Above 723 K, the high carbon austenite also decomposes to ferrite and cementite due to the fast diffusion of Si. Conversely, below 623 K, cementite is stabilized even without the diffusion of Si. These cementite formation mechanisms prevent the formation and retention of high carbon austenite. The inhomogeneous carbon distribution and cementite formation must be carefully considered to precisely predict the microstructure formation in Si-added bainitic steels.
27
Setargew, Nega, and Daniel J. Parker. "Zinc diffusion induced precipitation of σ-phase in austenitic stainless steel." Metallurgical Research & Technology 116, no. 6 (2019): 618. http://dx.doi.org/10.1051/metal/2019040.
Full textAbstract:
Zinc diffusion-induced degradation of AISI 316LN austenitic stainless steel pot equipment used in 55%Al-Zn and Zn-Al-Mg coating metal baths is described. SEM/EDS analyses results showed that the diffused zinc reacts with nickel from the austenite matrix and results in the formation of Ni-Zn intermetallic compounds. The Ni-Zn intermetallic phase and the nickel depleted zones form a periodic and alternating layered structure and a mechanism for its formation is proposed. The role of cavities and interconnected porosity in zinc vapour diffusion-induced degradation and formation of Ni-Zn intermediate phases is also discussed. The formation of Ni-Zn intermediate phases and the depletion of nickel in the austenite matrix results in the precipitation of σ-phase and α-ferrite in the nickel depleted regions of the matrix. This reaction will lead to increased susceptibility to intergranular cracking and accelerated corrosion of immersed pot equipment in the coating bath. Zinc diffusion induced precipitation of σ-phase in austenitic stainless steels that we are reporting in this work is a new insight with important implications for the performance of austenitic stainless steels in zinc containing metal coating baths and other process industries. This new insight will further lead to improved understanding of the role of substitutional diffusion and the redistribution of alloying elements in the precipitation of σ-phase in austenitic stainless steels.
28
Celada Casero, Carola, and David San Martín. "Austenite Formation in a Cold-Rolled Semi-austenitic Stainless Steel." Metallurgical and Materials Transactions A 45, no. 4 (October 31, 2013): 1767–77. http://dx.doi.org/10.1007/s11661-013-2077-0.
Full text
29
Zhang, Xianguang, Goro Miyamoto, Yuki Toji, and Tadashi Furuhara. "Effects of Heating Rate on Formation of Globular and Acicular Austenite during Reversion from Martensite." Metals 9, no. 2 (February 24, 2019): 266. http://dx.doi.org/10.3390/met9020266.
Full textAbstract:
The effects of heating rate on the formation of acicular and globular austenite during reversion from martensite in Fe–2Mn–1.5Si–0.3C alloy have been investigated. It was found that a low heating rate enhanced the formation of acicular austenite, while a high heating rate favored the formation of globular austenite. The growth of acicular γ was accompanied by the partitioning of Mn and Si, while the growth of globular γ was partitionless. DICTRA simulation revealed that there was a transition in growth mode from partitioning to partitionless for the globular austenite with an increase in temperature at high heating rate. High heating rates promoted a reversion that occurred at high temperatures, which made the partitionless growth of globular austenite occur more easily. On the other hand, the severer Mn enrichment into austenite at low heating rate caused Mn depletion in the martensite matrix, which decelerated the reversion kinetics in the later stage and suppressed the formation of globular austenite.
30
HINTZE CESARO, ALEJANDRO, and PATRICIO F. MENDEZ. "Effect of the Heating Rate on Austenite Formation." Welding Journal 100, no. 10 (October 1, 2021): 338–47. http://dx.doi.org/10.29391/2021.100.030.
Full textAbstract:
The extent of the heat-affected zone (HAZ) in welding is typically estimated from thermodynamic considerations of austenization; however, thermodynamics are a poor predictor of the HAZ location in microalloyed steels. This work addresses the problem through the study of austenite formation during continuous heating on a grade X80 pipeline steel with an initial ferritic and bainitic microstructure. The methodology involved dilatometry, electron microscopy, and thermodynamic calculations. A continuous heating transformation diagram was developed for heating rates varying from 1˚ to 500˚C/s. For the slower heating rates, austenite start-transformation temperature was higher than the one dictated by the equilibrium, while for the faster heating rates, start-transformation temperature gradually approached the theoretically calculated temperature at which the ferrite can transform (possibly through a massive transformation) without a long-range diffusion into austenite. Partial-transformation experiments suggested that austenite formation occurs in the following two stages: 1) the transformation of bainitic zones into austenite, and later, 2) the transformation of polygonal ferritic grains.
31
Safonov, E. N., and M. V. Mironova. "Surface Electric Arc Hardening of Low-Carbon Steels." Materials Science Forum 989 (May 2020): 318–23. http://dx.doi.org/10.4028/www.scientific.net/msf.989.318.
Full textAbstract:
Examined geometric characteristics, microhardness and features of structure formation in the heat affected zone of steels 09G2, 20L, 20FL. These studies were carried out after surface quenching by a magnetically controlled (scanning) DC electric arc in a protective argon atmosphere. It is shown that electric arc hardening forms on the treated surface of the steel a thin layer of martensitic-austenitic structure with varying composition and hardness. A ferrite-austenitic structure is formed in the region of transition from the base metal to the heat-strengthened metal. This structure contains crushed ferrite grain and winding boundaries between the structural components. On the periphery of austenitic grains martensitic layer is observed. Repeated heating, occurring during heat treatment of the adjacent surface area, is accompanied by a partial decay of martensite and austenite of a pre-hardened structure with the formation of bainite-and sorbitol-like tempering structures. On the surface, experienced repeated heating, the volume fraction of austenite increases. The dependences allowing to control the structural state and depth of the hardening zone are established.
32
Moskvina, V. A., E. V. Melnikov, and E. A. Zagibalova. "CHARACTERISTICS OF A GRADIENT MATERIAL BASED ON NI-CR STAINLESS STEEL AND H20N80 ALLOY PRODUCED BY ELECTRON-BEAM 3D-PRINTING." Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta, no. 3 (2021): 57–66. http://dx.doi.org/10.18323/2073-5073-2021-3-57-66.
Full textAbstract:
The main problem of additively manufactured chromium-nickel austenitic stainless steels is the formation of a two-phase γ-austenite/δ-ferrite dendritic microstructure, which complicates their use and distinguishes them from cast single-phase analogs. The reasons for the formation of a two-phase structure are nonequilibrium solidification conditions, complex thermal history, and melt depletion by austenite-forming elements (nickel and manganese). Therefore, additional nickel alloying under the additive manufacturing of steels can stabilize the austenitic structure in them. In this work, the authors used electron-beam additive production with simultaneous feeding of two wires from austenitic stainless steel Fe-18.2Cr-9.5Ni-1.1Mn-0.7Ti-0.5Si-0.08C wt.% (SS, Cr18Ni10Ti) and alloy 77.7Ni-19.6Cr-1.8Si-0.5Fe-0.4Zr wt.% (Ni-Cr alloy, Cr20Ni80) to obtain two gradient billets. The authors used two wire-feeding strategies (the first one is four layers of SS/one layer of Cr20Ni80; the second one is one layer of SS/one layer of a mixture 80 % SS + 20 % Cr20Ni80). The study identified that the Ni-Cr alloying in the process of electron-beam additive production of SS billets suppressed δ-ferrite formation and contributes to the stabilization of the austenite phase. The deposition of Ni-Cr alloy next to the four layers of SS leads to inhomogeneity of the structure and chemical composition in the billet, low plasticity, and premature failure of these specimens during tensile tests. The sequential alternation of pure SS layers with those of a mixture of wires (80 % SS + 20 % Cr20Ni80) promotes the uniform mixing of two wires components and the formation of a more homogeneous structure in the gradient billet, which leads to an increase in the ductility of the specimens during mechanical tests.
33
Vodárek, Vlastimil, Carl Peter Reip, and Anastasia Volodarskaja. "Microstructure Evolution in Belt-Casted Strip of Grain Oriented Electrical Steel." Key Engineering Materials 810 (July 2019): 82–88. http://dx.doi.org/10.4028/www.scientific.net/kem.810.82.
Full textAbstract:
This paper deals with the formation and decomposition of Widmanstätten austenite during solidification of the thin belt-casted strip made of a grain oriented electrical steel (GOES). Solidification of liquid steel starts with the formation of d-ferrite. Cooling in the delta + gama phase field results in the formation of a small fraction of Widmanstätten austenite by displacive transformation accompanied by carbon partition. Widmanstätten austenite laths have an orientation relationship with the ferrite grain into which they grow. Furthermore, they form a flat low energy interface along the ferrite grain boundary. In order to minimize the interfacial energy, ferrite grain boundaries in the vicinity of flat austenite/ferrite interface facets are forced to migrate which results in straightening of these grain boundaries. If parallel Widmanstätten austenite laths form in two adjacent ferrite grains, zig–zag ferrite grain boundaries arise. Precipitation of sulphides along ferrite/austenite interfaces make it possible to study the early stages of austenite decomposition under the delta + gama phase field. It starts with the formation of epitaxial ferrite accompanied by further partitioning of carbon into remaining austenite. The growth of epitaxial ferrite into the flat ferrite/austenite interface facets along ferrite grain boundaries results in a wavy shape of these ferrite grain boundaries. Finally austenite transforms either to pearlite or to plate martensite.
34
Huang, J., W. J. Poole, and M. Militzer. "Austenite formation during intercritical annealing." Metallurgical and Materials Transactions A 35, no. 11 (November 2004): 3363–75. http://dx.doi.org/10.1007/s11661-004-0173-x.
Full text
35
Gallegos-Pérez, Alexis Iván, Octavio Vázquez-Gómez, Martín Herrejón-Escutia, Héctor Javier Vergara-Hernández, Sixtos Antonio Arreola-Villa, Pedro Garnica-González, and Edgar López-Martínez. "Application of a Non-Isothermal Numerical-Analytical Model to Determine the Kinetics of Austenite Formation in a Silicon Alloyed Steel." Materials 15, no. 4 (February 13, 2022): 1376. http://dx.doi.org/10.3390/ma15041376.
Full textAbstract:
A non-isothermal transformation model was proposed to determine the austenite formation kinetics in a steel alloyed with 2.6% wt. Si by dilatometric analysis, considering that the nucleation mechanism does not change with the heating rate. From the dilatometric analysis, it was observed that the austenite formation occurs in two stages; critical temperatures, degree and austenite formation rate were determined. The activation energies associated with each of the stages were obtained employing the Kissinger method (226.67 and 198.37 kJ·mol−1 for the first and second stage) which was used in concert with the austenite formation rate in the non-isothermal model as a first approximation, with acceptable results in the second stage, but not in the first due to the activation energies magnitude. Then, the activation energies were adjusted by minimizing the minimal squares error between estimated and experimental austenite formation degree, obtaining values of 158.50 kJ·mol−1 for the first and 165.50 kJ·mol−1 for the second stage. These values are consistent with those reported for the diffusion of carbon in austenite-FCC in silicon steels. With these activation energies it was possible to predict the austenite formation degree with a better level of convergence when implementing the non-isothermal model.
36
ADACHI, Y., M. WAKITA, H. BELADI, and P. D. HODGSON. "THE FORMATION OF ULTRAFINE FERRITE THROUGH STATIC TRANSFORMATION IN LOW CARBON STEELS." International Journal of Modern Physics B 22, no. 18n19 (July 30, 2008): 2804–13. http://dx.doi.org/10.1142/s0217979208047626.
Full textAbstract:
A novel approach was used to produce an ultrafine grain structure in low carbon steels with a wide range of hardenability. This included warm deformation of supercooled austenite followed by reheating in the austenite region and cooling (RHA). The ultrafine ferrite structure was independent of steel composition. However, the mechanism of ferrite refinement changed with the steel quench hardenability. In a relatively low hardenable steel, the ultrafine structure was produced through dynamic strain induced transformation, whereas the ferrite refinement was formed by static transformation in steels with high quench hardenability. The use of a model Ni -30 Fe austenitic alloy revealed that the deformation temperature has a strong effect on the nature of the intragranular defects. There was a transition temperature below which the cell dislocation structure changed to laminar microbands. It appears that the extreme refinement of ferrite is due to the formation of extensive high angle intragranular defects at these low deformation temperature that then act as sites for static transformation.
37
Hell, Jean Christophe, Moukrane Dehmas, Guillaume Geandier, Nathalie Gey, Sebastien Allain, Alain Hazotte, and Jean Philippe Chateau. "Influence of the Austempering Temperature on the Microstructure and Crystallography of a Carbide-Free Bainitic Steel." Solid State Phenomena 172-174 (June 2011): 797–802. http://dx.doi.org/10.4028/www.scientific.net/ssp.172-174.797.
Full textAbstract:
We elaborated two carbide-free bainitic steels with different microstructures through specific heat treatments and alloy design. EBSD analysis was used to point out major differences in these microstructures. In-situ characterizations of the bainitic transformation were performed by high energy synchrotron diffraction to go further into the study of each phase characteristics. The elaborated microstructures exhibited various phase fractions of bainitic ferrite, retained austenite and blocks of martensite and retained austenite. Moreover, the volume fraction of retained austenite increased with higher austempering temperatures. On the other hand, the austempering temperatures showed a strong influence on the kinetics of the bainitic transformation. Isothermal transformation under Ms showed a two stage transformation which led first to the formation of self-tempered martensite and then to bainitic ferrite. Furthermore, the evolution of the austenitic cell parameter showed enrichment in carbon ruled by diffusional mechanisms.
38
Tarraste, Marek, Jakob Kübarsepp, Kristjan Juhani, Märt Kolnes, Mart Viljus, and Arvo Mere. "Sintering of High Mn Cemented Carbides in Mn-Rich Environment." Defect and Diffusion Forum 405 (November 2020): 402–7. http://dx.doi.org/10.4028/www.scientific.net/ddf.405.402.
Full textAbstract:
The economic, environmental and healthcare aspects are pushing cemented carbide industry to reduce or even avoid the usage of conventional binder metals – nickel and cobalt. Commonly, austenitic Fe-Ni alloys have been preferred choice for substituting Co. Similar to Ni, manganese acts as austenite stabilizer and studies have shown that Fe-Mn alloys offer alternative binder metal to Co and Ni in cemented tungsten carbides. In addition, Fe-Mn as a binder potentially offers improved wear resistance due to the well-known wear properties of Fe-Mn-C steels. Addition of chromium to the binder composition increases corrosion performance of composite. Cemented carbides bonded with austenitic FeCrNi binder have demonstrated promising performance. In present work the possibility of achieving austenitic binder phase through substitution of nickel by manganese as an austenite stabilizer is investigated. Structure formation, phase composition and mechanical performance of WC-FeMn and WC-FeCrMn cemented carbides are discussed.
39
Barbé, L., K. Conlon, and B. C. De Cooman. "Characterization of the metastable austenite in low-alloy FeCMnSi TRIP-aided steel by neutron diffraction." International Journal of Materials Research 93, no. 12 (December 1, 2002): 1217–27. http://dx.doi.org/10.1515/ijmr-2002-0210.
Full textAbstract:
Abstract The detailed analysis of X-ray diffraction data obtained from intercritically annealed and isothermally transformed low-alloy FeCMnSi TRIP-aided steels reveals that the microstructure contains athermal plate martensite and Fe2C η carbide in addition to ferrite, bainite and residual austenite. Neutron diffraction shows that athermal plate martensite can be formed at room temperature in the isolated austenite phase. Whereas the formation of athermal martensite leads to compressive strains in the austenite, the formation of strain-induced martensite results in tensile straining of the austenite. The strain-induced transformation leads to the formation of a martensite of low tetragonality. Low-temperature annealing leads to the formation of η carbide in both the athermal and strain-induced martensite.
40
Zhou, Rui, Xuan Wang, Cheng Liu, and Derek O. Northwood. "Self-organized Formation of Multilayer Structure in a High Nitrogen Stainless Steel during Solution Treatment." MRS Advances 4, no. 5-6 (2019): 271–76. http://dx.doi.org/10.1557/adv.2019.42.
Full textAbstract:
ABSTRACTCompared with traditional stainless steels, high nitrogen stainless steels (HNSS), have been widely used due to their high strength, toughness along with excellent corrosion resistance and low cost, formed by partial replacement of Ni (austenite-forming element) by N. The evolution of the microstructure of a Cr19Mn19Mo2N0.7 stainless steel is investigated after solution treatment at 1010, 1060, 1200 or 1250°C for 30min. A complex multilayer structure has been found under a negative pressure vacuum. A white ferritic layer at the surface is formed, and a subsurface layer with full austenitic structure and a bulk microstructure comprising of austenite and ferrite are detected. With increasing solution temperature, the surface layer thickness increases. The formation of the multilayer structure is attributed to an outward diffusion, a diffusive retardation and an abnormal accumulation of nitrogen during solution treatment.
41
Gołębiowski, Bartosz, and Wiesław Świątnicki. "Microstructural Changes Induced during Hydrogen Charging Process in Stainless Steels with and without Nitrided Layers." Solid State Phenomena 186 (March 2012): 305–10. http://dx.doi.org/10.4028/www.scientific.net/ssp.186.305.
Full textAbstract:
The purpose of this study is to analyze the effect of glow discharge nitriding on hydrogen degradation of two types of steels: two-phase austenitic-ferritic and single-phase austenitic. The nitriding process resulted in formation of surface layers composed of expanded austenite (S phase), and in the case of two-phase steel of expanded austenite and expanded ferrite. Microstructural changes occurring under the influence of hydrogen on steels without and with nitrided layers were investigated with the use of scanning (SEM) and transmission (TEM) electron microscopy techniques. It was shown that the density of cracks formed during cathodic hydrogen charging is higher on the surface of the non-nitrided steels compared to the nitrided steels after identical hydrogen charging process. Moreover in non nitrided steel hydrogenation leads to considerable increase of dislocation density, which results from the high concentration of hydrogen absorbed to the steel during its cathodic charging. This leads in turn to high stress concentration and local embrittlement giving rise to cracks formation. Conversely nitriding reduces the absorption of hydrogen and prevents structural changes resulting in hydrogen embrittlement. The conducted studies show that glow discharge nitriding can be used to increase resistance to hydrogen embrittlement of austenitic and austenitic ferritic stainless steels.
42
Mohanty, R. R., and O. A. Girina. "Effect of Coiling Temperature on Kinetics of Austenite Formation in Cold Rolled Advanced High Strength Steels." Materials Science Forum 706-709 (January 2012): 2112–17. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.2112.
Full textAbstract:
A systematic experimental investigation was conducted using lab processed low carbon 0.08C-2.0Mn-Cr-Mo steel microalloyed with Ti/Nb to evaluate the influence of initial hot-rolled microstructures on the kinetics of austenite formation and decomposition after cold-rolling and subsequent annealing. Coiling temperature as a major hot rolling parameter was used to obtain different types of hot-rolled microstructures. Dilatometer and continuous annealing simulator were employed for austenite formation studies and annealing simulations, respectively. It was found that the coiling temperature affects the processes occurring during heat treatment in continuous annealing lines of full hard material: ferrite recrystallization, austenite formation during continuous heating and austenite decomposition during cooling. A decrease in coiling temperature accelerates the recrystallization of ferrite and nucleation of austenite, which results in formation of refined ferrite-martensite structure. The effect of initial hot rolled structure on final mechanical properties after continuous annealing was also investigated.
43
Ramesh, Aditya, Vishal Kumar, Anuj, and Pradeep Khanna. "Weldability of duplex stainless steels- A review." E3S Web of Conferences 309 (2021): 01076. http://dx.doi.org/10.1051/e3sconf/202130901076.
Full textAbstract:
Duplex stainless steel finds widespread use in various sectors of manufacturing and related fields. It has many advantages due to its distinctive structural combination of austenite and ferrite grains. It is the need of the current generation due to its better corrosive resistance over high production austenitic stainless steels. This paper reviews the weldability of duplex stainless steels, mentions the reason behind the need for duplex stainless steels and describes how it came into existence. The transformations in the heat-affected zones during the welding of duplex stainless steels have also been covered in this paper. The formation, microstructure and changes in high temperature and low temperature heat-affected zones have been reviewed in extensive detail. The effects of cooling rate on austenite formation has been briefly discussed. A comparison of weldability between austenitic and duplex stainless steel is also given. Finally, the paper reviews the applications of the various grades of duplex stainless steel in a variety of industries like chemical, paper and power generation and discusses the future scope of duplex stainless steel in various industrial sectors.
44
Ryś, Janusz, Wiktoria Ratuszek, and Małgorzata Witkowska. "The Effect of Initial Orientation and Rolling Schedule on Texture Development in Duplex Steel." Materials Science Forum 495-497 (September 2005): 375–80. http://dx.doi.org/10.4028/www.scientific.net/msf.495-497.375.
Full textAbstract:
A development of deformation textures was examined in ferritic-austenitic duplex type steel subjected to cold-rolling within the range up to 90% of reduction by applying different rolling schedules. The investigations included X-ray phase analysis, texture measurements and microstructure observations by means of light microscopy. The experimental results indicate at the occurrence of strong initial textures in both component phases after preliminary thermo-mechanical treatment. Formation of the ferrite-austenite banded structure in the course of rolling along with the stability of major texture components, related by Bain orientation relationship, exert considerable effect on the development of the ferrite and austenite rolling textures.
45
Zhang, Fang. "Modeling of Non-Isothermal Austenite Formation in Cr5 Roller Steel." Advanced Materials Research 712-715 (June 2013): 34–37. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.34.
Full textAbstract:
A modified model describing the austenite reaction was developed that took into account the effect of heating rate. The model considered the variation of activation energy during non-isothermal heating and one set of model parameter was adequate to predict the formation of austenite. To verify the theoretical model, the process of austenite formation during continuous heating in Cr5 roller steel with pearlite and ferrite mixed initial microstructure was analyzed by dilatation experiment. The results show that a strong logarithmic relationship between apparent activation energy and heating rate. Experimental kinetic transformations as well as critical temperatures of austenite reaction are in good agreement with the calculations. The model can be used to describe the transformation kinetics at an intermediate heating rate.
46
Redjaïmia, Abdelkrim, and Antonio Manuel Mateo Garcia. "On the M23C6-Carbide in 2205 Duplex Stainless Steel: An Unexpected (M23C6/Austenite)—Eutectoid in the δ-Ferritic Matrix." Metals 11, no. 9 (August 25, 2021): 1340. http://dx.doi.org/10.3390/met11091340.
Full textAbstract:
This study is focused on isothermal and anisothermal precipitation of M23C6 carbides from the fully ferritic structure of the (γ + δ) austenitic-ferritic duplex stainless steel X2CrNiMo2253, (2205). During isothermal heat treatments, small particles of K-M23C6 carbide precipitates at the δ/δ grain-boundaries. Their formation precedes γ and σ-phases, by acting as highly potential nucleation sites, confirming the undertaken TEM investigations. Furthermore, anisothermal heat treatment leads to the formation of very fine islands dispersed throughout the fully δ-ferritic matrix. TEM characterization of these islands reveals a particular eutectoid, reminiscent of the well-known (γ-σ)—eutectoid, usually encountered in this kind of steel. TEM and electron microdiffraction techniques were used to determine the crystal structure of the eutectoid constituents: γ-Austenite and K-M23C6 carbides. Based on this characterization, orientation relationships between the two latter phases and the ferritic matrix were derived: cube-on-cube, on one hand, between K-M23C6 and γ-Austenite and Kurdjumov-Sachs, on the other hand, between γ-Austenite and the δ-ferritic matrix. Based on these rational orientation relationships and using group theory (symmetry analysis), the morphology and the only one variant number of K-M23C6 in γ-Austenite have been elucidated and explained. Thermodynamic calculations, based on the commercial software ThermoCalq® (Thermo-Calc Software, Stockholm, Sweden), were carried out to explain the K-M23C6 precipitation and its effect on the other decomposition products of the ferritic matrix, namely γ-Austenite and σ-Sigma phase. For this purpose, the mole fraction evolution of K-M23C6 and σ-phase and the mass percent of all components entering in their composition, have been drawn. A geometrical model, based on the corrugated compact layers instead of lattice planes with the conservation of the site density at the interface plane, has been proposed to explain the transition δ-ferrite ⇒ {γ-Austenite ⇔ K-M23C6}.
47
Jiang, Wen, and Kunyu Zhao. "Effect of Cu on the Formation of Reversed Austenite in Super Martensitic Stainless Steel." Materials 16, no. 3 (February 3, 2023): 1302. http://dx.doi.org/10.3390/ma16031302.
Full textAbstract:
We investigated the effect of Cu on the formation of reversed austenite in super martensitic stainless steel by using X-ray diffraction (XRD), a transmission electron microscope (TEM) and an energy-dispersive spectrometer (EDS). Our results showed that the microstructure of the steels comprised tempered martensite and diffused reversed austenite after the steels were quenched at 1050 °C and tempered at 550–750 °C. The volume fraction of reversed austenite in the steel with 3 wt.% of Cu (3Cu) was more than that with 1.5 wt.% of Cu (1.5Cu). The transmission electron microscope results revealed that the reversed austenite in 1.5Cu steel mainly had the shape of a thin strip, while that in 3Cu steel had a block shape. The nucleation points and degree of Ni enrichment of reversed austenite in 3Cu steel were higher than those in 1.5Cu steel. The reversed austenite was more likely to grow in ε-Cu enriched regions. Therefore, Cu can promote reversed austenite nucleation and growth. The mechanical properties of 3 Cu steel are obviously better than those of 1.5Cu steel when tempered at 550–650 °C.
48
Cheng, Wei Chun, Kun Hsien Lee, Shu Mao Lin, and Shao Yu Chien. "The Observation of Austenite to Ferrite Martensitic Transformation in an Fe-Mn-Al Austenitic Steel after Cooling from High Temperature." Materials Science Forum 879 (November 2016): 335–38. http://dx.doi.org/10.4028/www.scientific.net/msf.879.335.
Full textAbstract:
Fe-Mn-Al steels with low density have the potential to substitute for TRIP (transformation induced plasticity) steels. For the development of Fe-Mn-Al TRIP steels, phase transformations play an important role. Our methods of studying the phase transformations of the Fe-16.7 Mn-3.4 Al (wt%) austenitic steel include heating and cooling. We have studied the martensitic transformation of the ternary Fe-Mn-Al steel. Single austenite phase is the equilibrium phase at 1373 K, and dual phases of ferrite and austenite are stable at low temperatures. It is noteworthy that lath martensite forms in the prior austenite grains after cooling from 1373 K via quenching, air-cooling, and/or furnace-cooling. The crystal structure of the martensite belongs to body-centered cubic. The formation mechanism of the ferritic martensite is different from the traditional martensite in steels. Ferrite is the stable phase at low temperature.
49
San Martin, D., E. Jiménez-Melero, J. A. Duffy, V. Honkimäki, S. van der Zwaag, and N. H. van Dijk. "Real-time synchrotron X-ray diffraction study on the isothermal martensite transformation of maraging steel in high magnetic fields." Journal of Applied Crystallography 45, no. 4 (July 4, 2012): 748–57. http://dx.doi.org/10.1107/s0021889812024892.
Full textAbstract:
The isothermal austenite-to-martensite transformation kinetics in a maraging steel have been studied by time-dependent microbeam diffraction measurements with high-energy X-rays. The transformation kinetics are shown to be accelerated significantly when a magnetic field of 8 T is applied. The average phase behaviour, obtained from a Rietveld refinement of the powder-averaged diffraction data, demonstrates that the martensite formation does not lead to a macroscopic strain in the austenite and martensite phases. An analysis of individual austenite reflections in the microbeam diffraction patterns, however, indicates that within the transforming austenite grains a transformation strain develops as a result of the formed martensite. The development of elastic strains during the transformation is explained by a partial strain confinement within the untransformed part of the austenite grain. The strain relaxation to the surrounding austenite grains is found to be dependent on the austenite volume. For a set of individual austenite grains the martensite nucleation is correlated with the initial austenite volume and the strain developed prior to the transformation as a result of martensite formation in the neighbouring grains.
50
Niessen, Frank, Flemming Bjerg Grumsen, John Hald, and Marcel Adrianius Johannes Somers. "Formation and stabilization of reverted austenite in supermartensitic stainless steel." Metallurgical Research & Technology 115, no. 4 (2018): 402. http://dx.doi.org/10.1051/metal/2018051.
Full textAbstract:
The formation and stabilization of reverted austenite upon inter-critical annealing was investigated in a X4CrNiMo16-5-1 (EN 1.4418) supermartensitic stainless steel by means of scanning electron microscopy, electron backscatter-diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy and dilatometry. The results were supported by thermodynamics and kinetics models, and hardness measurements. Isothermal annealing for 2 h in the temperature range of 475 to 650 °C led to gradual softening of the material which was related to tempering of martensite and the steady increase of the reverted austenite phase fraction. Annealing at higher temperatures led to a gradual increase in hardness which was caused by formation of fresh martensite from reverted austenite. It was demonstrated that stabilization of reverted austenite is primarily based on chemical stabilization by partitioning, consistent with modeling results.