scholarly journals Effects of Temperature and Time of Isothermal Holding on Retained Austenite Stability in Medium-Mn Steels

2018 ◽  
Vol 8 (11) ◽  
pp. 2156 ◽  
Author(s):  
Adam Grajcar ◽  
Paweł Skrzypczyk ◽  
Aleksandra Kozłowska
Keyword(s):  
Retained Austenite ◽  
Thermomechanical Processing ◽  
Isothermal Holding ◽  
Optimal Time ◽  
X Ray Diffraction ◽  
Noticeable Effect ◽  
Austenite Stability ◽  
Bainitic Steels ◽  
The Stability ◽  
Microscopy Techniques

Effects of isothermal holding time and temperature on the stability of retained austenite in medium manganese bainitic steels with and without Nb microaddition were investigated. The amount of retained austenite for various variants of thermomechanical processing was determined by X-ray diffraction. Relationships between processing conditions and microstructure were revealed using light microscopy and scanning electron microscopy techniques. The isothermal holding temperatures changed from 500 to 300 °C and the time was from 60 to 1800 s. The optimal time and temperature of isothermal holding for all the investigated steels were 400 °C and 300 s, respectively. The relationships between the Mn content, amount of retained austenite, and carbon enrichment of the retained austenite (RA) were observed. The noticeable effect of Nb microaddition on the amount of retained austenite was not observed. In general, the carbon content in RA was slightly lower for the steels containing Nb. The optimum gamma phase amount was up to 18% for the 3% Mn steels, whereas it was c.a. 13% for the steels with 5% Mn. It was found that the morphology of blocky/interlath retained austenite depends substantially on the isothermal holding temperature.

Effect of Thermomechanical Processing on the Microstructure and Retained Austenite Stability during In Situ Tensile Testing Using Synchrotron X-Ray Diffraction of NbMoAl TRIP Steel

2011 ◽  
Vol 172-174 ◽  
pp. 741-746 ◽  
Author(s):  
Elena V. Pereloma ◽  
Lai Chang Zhang ◽  
Klaus Dieter Liss ◽  
Ulf Garbe ◽  
Jonathan Almer ◽  
...  
Keyword(s):  
Tensile Testing ◽  
Retained Austenite ◽  
Thermomechanical Processing ◽  
Critical Role ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Stability

In this work we compare and contrast the stability of retained austenite during tensile testing of Nb-Mo-Al transformation-induced plasticity steel subjected to different thermomechanical processing schedules. The obtained microstructures were characterised using optical metallography, transmission electron microscopy and X-ray diffraction. The transformation of retained austenite to martensite under tensile loading was observed by in-situ high energy X-ray diffraction at 1ID / APS. It has been shown that the variations in the microstructure of the steel, such as volume fractions of present phases, their morphology and dimensions, play a critical role in the strain-induced transition of retained austenite to martensite.

scholarly journals Laboratory- and Semi-Industrial-Scale Thermomechanical Processing of TRIP-Aided Steel with Acicular Ferrite

2021 ◽  
Vol 11 (20) ◽  
pp. 9512
Author(s):  
Adam Skowronek ◽  
Adam Grajcar
Keyword(s):  
Mechanical Properties ◽  
Acicular Ferrite ◽  
Retained Austenite ◽  
Thermomechanical Processing ◽  
Isothermal Holding ◽  
Industrial Process ◽  
Tensile Tests ◽  
Slow Cooling ◽  
Multiphase Microstructure ◽  
The Stability

The modification of the deformation and cooling methods resulting in the obtainment of acicular ferrite promotes an increase in the proportion of retained austenite (RA) and a corresponding increase in mechanical properties in Si-Al TRIP-aided steel. The effect of controlled thermomechanical processing in laboratory- and semi-industrial scales on the possibility of obtaining acicular ferrite and a high fraction of retained austenite was investigated. The steel was hot deformed in three steps: at 1050, 900 and 750 ˚C to introduce dislocations into the hot-deformed pancake austenite. Next, slow cooling in a ferritic transformation region was performed, followed by isothermal holding of steel at 450 ˚C. The interrupted tensile tests at the strain levels of 5, 10 and 15% were performed to investigate the mechanical properties response and the stability of the obtained retained austenite. Light and scanning electron microscopy, XRD and EBSD analyses were performed to assess microstructural features. The produced material showed a multiphase microstructure containing acicular ferrite and 10% of retained austenite. The microstructures obtained in both production methods were slightly different due to high temperature inertia in the semi-industrial process.

Temperature-Dependent Mechanical Stability of Retained Austenite in Thermomechanically Processed 3Mn Steel

2021 ◽  
Vol 1016 ◽  
pp. 762-767
Author(s):  
Aleksandra Kozłowska ◽  
Adam Grajcar ◽  
Aleksandra Janik ◽  
Krzysztof Radwański
Keyword(s):  
Retained Austenite ◽  
Mechanical Stability ◽  
Electron Backscatter Diffraction ◽  
Tensile Tests ◽  
Trip Effect ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Static Tensile ◽  
The Stability ◽  
Backscatter Diffraction

The temperature-dependent mechanical stability of retained austenite in medium-Mn transformation induced plasticity 0.17C-3.3Mn-1.6Al-1.7Al-0.22Si-0.23Mo thermomechanically processed steel was investigated using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) methods. Specimens were deformed up to rupture in static tensile tests in a temperature range 20–200°C. It was found that deformation temperature affects significantly the intensity of TRIP effect. In case of specimens deformed at temperatures higher than 60°C, a gradual temperature-related decrease in the stability of γ phase was noted. It indicates a progressive decrease of the significance of the TRIP effect and at the same time the growing importance of the thermally activated processes affecting a thermal stability of retained austenite.

Effect of Retained Austenite Stability on Mechanical Properties of Bainitic Rail Steel

2014 ◽  
Vol 1004-1005 ◽  
pp. 198-202 ◽  
Author(s):  
Kai Kai Wang ◽  
Zhun Li Tan ◽  
Gu Hui Gao ◽  
Xiao Lu Gui ◽  
Bing Zhe Bai
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Retained Austenite ◽  
Rail Steel ◽  
High Impact ◽  
Good Thermal Stability ◽  
Austenite Stability ◽  
Retained Austenite Stability ◽  
Close Relationship ◽  
The Stability

Retained austenite has an important effect on strength and toughness of 20Mn2SiCrMo bainitic rail steel. In this work, the stability of retained austenite and mechanical properties have been studied. The results show that impact toughness of experimental steel has close relationship with the stability of retained austenite. When tempered at lower than 350°C, retained austenite owns good thermal stability, corresponding to relatively high impact toughness.

The effect of retained austenite stability on impact-abrasion wear resistance in carbide-free bainitic steels

Wear ◽  
2019 ◽  
Vol 428-429 ◽  
pp. 127-136 ◽  
Author(s):  
Binggang Liu ◽  
Wei Li ◽  
Xianwen Lu ◽  
Xiaoshuai Jia ◽  
Xuejun Jin
Keyword(s):  
Wear Resistance ◽  
Retained Austenite ◽  
Austenite Stability ◽  
Retained Austenite Stability ◽  
Abrasion Wear ◽  
Bainitic Steels

Effect of Aluminum and Vanadium on Retained Austenite Stability and Work Hardening in Silicon Free TRIP Steel

2020 ◽  
Vol 835 ◽  
pp. 347-352
Author(s):  
Ahmed El-Sherbiny ◽  
Mohamed Kamal El-Fawkhry ◽  
Ahmed Y. Shash ◽  
Tarek M. El-Hossainy ◽  
Ayman Mohamed Fathy ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Trip Steel ◽  
Retained Austenite ◽  
X Ray Diffraction ◽  
Alloying Element ◽  
Etching Technique ◽  
Complete Replacement ◽  
Austenite Stability ◽  
Retained Austenite Stability ◽  
Strong Candidate

Despite that the conventional CSiMn TRIP steel has a promissing mechanical attributes, it has a limitations on the galvanizability of such grades of steel due to Silicon. Thus, aluminum as a strong candidate for substituting silicon has been introduced in this study accompanied by vanadium as a microalloying element. Microstructure of the studied steel was observed by using OM, and SEM. X-ray diffraction analysis, and tent-etching technique carried out on the studied steel to identify the fractions of the retained Austenite after thermal mechanical process, as well as its morphology. In addition, the mechanical properties in term of strength, ductility, strain hardening, and the rate of strain hardening were studied to define the influenced parameters throughout this alteration. The results refer to the possibility of complete replacement of silicon in TRIP steel with aluminum at the presence of vanadium as a micro alloying element.

Growth, Crystal Structure and Stability of Ag-Ni/Cu Films

2006 ◽  
Vol 514-516 ◽  
pp. 1166-1170 ◽  
Author(s):  
Igor K. Bdikin ◽  
Galina K. Strukova ◽  
G.V. Strukov ◽  
V.V. Kedrov ◽  
D.V. Matveev ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
X Ray Diffraction ◽  
Pure Silver ◽  
X Ray ◽  
Cu Films ◽  
Grain Sizes ◽  
Cu Substrates ◽  
The Stability ◽  
Microscopy Techniques

AgxNi1-x (x=0.0-1.0) films were grown on Cu substrates by electrodeposition method. The films were found to be a nanocrystalline mixture of pure silver and nickel. The grain sizes were determined by X-ray diffraction and electron microscopy techniques. The minimal value was 3.3 m for the alloy with 70 wt% concentration of Ni. The stability of the grown films upon heating in ir and in vacuum was examined. An increase in the grain size was found to begin at 150°C.

scholarly journals Microstructural Control of the Austenite Stability in Low-Alloyed TRIP Steels

2011 ◽  
Vol 172-174 ◽  
pp. 196-201 ◽  
Author(s):  
Romain Blondé ◽  
Enrique Jimenez-Melero ◽  
Niels H. van Dijk ◽  
Ekkes Brück ◽  
Lie Zhao ◽  
...  
Keyword(s):  
Retained Austenite ◽  
Room Temperature ◽  
High Energy ◽  
X Ray Diffraction ◽  
Trip Steels ◽  
Austenite Stability ◽  
Treatment Conditions ◽  
Holding Temperature ◽  
Initial Fraction

We have performed in-situ magnetization and high-energy X-ray diffraction measurements on two aluminum-based TRIP steels from room temperature down to 100 K in order to evaluate amount and stability of the retained austenite for different heat treatment conditions. We have found that the bainitic holding temperature affects the initial fraction of retained austenite at room temperature but does not to influence significantly the rate of transformation upon cooling.

Effect of Retained Austenite Stability on Mechanical Properties of 590MPa Grade TRIP Sheet Steels

2010 ◽  
Vol 638-642 ◽  
pp. 3374-3379 ◽  
Author(s):  
Hiroshi Matsuda ◽  
Hisata Noro ◽  
Yasunobu Nagataki ◽  
Yoshihiro Hosoya
Keyword(s):  
Mechanical Properties ◽  
Carbon Content ◽  
Retained Austenite ◽  
High Strain ◽  
Sheet Steels ◽  
Trip Steels ◽  
Austenite Stability ◽  
Retained Austenite Stability ◽  
The Stability ◽  
High Work

Industrial low alloy TRIP sheet steels contain blocky and lath-shaped retained austenite. In the present study, transformation behaviour of blocky and lath-shaped retained austenite during straining was investigated to clarify its effect on mechanical properties. Two types of TRIP steels containing almost the same amount but the different morphology of retained austenite were used. A steel containing large amount of lath-shaped retained austenite exhibits superior ductility, and sustains high work-hardenability in a high strain region. On the contrast, a steel containing large amount of blocky retained austenite exhibits low ductility. 　The work-hardenability increased steeply to the maximum at a low strain region, and then reduced in a high strain region. The stability of the blocky austenite has been found to be poor with respected to martensite transformation. The lath-shaped retained austenite remains until a high strain region whereas the blocky retained austenite transformed into martensite in a low strain region. Carbon content was higher in the lath-shaped retained austenite than in the blocky retained austenite. Stability of retained austenite is, however, inexplicable only by the carbon content, and would be affected by the different morphology and the resulting restraint conditions.

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