scholarly journals Structural Transformations and Mechanical Properties of Metastable Austenitic Steel under High Temperature Thermomechanical Treatment

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 645
Author(s):  
Igor Litovchenko ◽  
Sergey Akkuzin ◽  
Nadezhda Polekhina ◽  
Kseniya Almaeva ◽  
Evgeny Moskvichev
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Temperature ◽  
Austenitic Steel ◽  
Structural Transformations ◽  
Initial State ◽  
Twin Boundaries ◽  
Metastable Austenitic Steel ◽  
Average Grain Size ◽  
Heating Up

The effect of high-temperature thermomechanical treatment on the structural transformations and mechanical properties of metastable austenitic steel of the AISI 321 type is investigated. The features of the grain and defect microstructure of steel were studied by scanning electron microscopy with electron back-scatter diffraction (SEM EBSD) and transmission electron microscopy (TEM). It is shown that in the initial state after solution treatment the average grain size is 18 μm. A high (≈50%) fraction of twin boundaries (annealing twins) was found. In the course of hot (with heating up to 1100 °C) plastic deformation by rolling to moderate strain (e = 1.6, where e is true strain) the grain structure undergoes fragmentation, which gives rise to grain refining (the average grain size is 8 μm). Partial recovery and recrystallization also occur. The fraction of low-angle misorientation boundaries increases up to ≈46%, and that of twin boundaries decreases to ≈25%, compared to the initial state. The yield strength after this treatment reaches up to 477 MPa with elongation-to-failure of 26%. The combination of plastic deformation with heating up to 1100 °C (e = 0.8) and subsequent deformation with heating up to 600 °C (e = 0.7) reduces the average grain size to 1.4 μm and forms submicrocrystalline fragments. The fraction of low-angle misorientation boundaries is ≈60%, and that of twin boundaries is ≈3%. The structural states formed after this treatment provide an increase in the strength properties of steel (yield strength reaches up to 677 MPa) with ductility values of 12%. The mechanisms of plastic deformation and strengthening of metastable austenitic steel under the above high-temperature thermomechanical treatments are discussed.

Critical grain size to limit the hydrogen-induced ductility drop in a metastable austenitic steel

2015 ◽  
Vol 40 (33) ◽  
pp. 10697-10703 ◽  
Author(s):  
Arnaud Macadre ◽  
Nobuo Nakada ◽  
Toshihiro Tsuchiyama ◽  
Setsuo Takaki
Keyword(s):  
Grain Size ◽  
Austenitic Steel ◽  
Metastable Austenitic Steel ◽  
Critical Grain Size

scholarly journals Microstructure and Mechanical Properties of 4Al Alumina-Forming Austenitic Steel after Cold-Rolling Deformation and Annealing

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2767 ◽  
Author(s):  
Chenchen Jiang ◽  
Qiuzhi Gao ◽  
Hailian Zhang ◽  
Ziyun Liu ◽  
Huijun Li
Keyword(s):  
Grain Size ◽  
Cold Rolling ◽  
Grain Boundaries ◽  
Austenitic Steel ◽  
Rolling Reduction ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Cold Rolling Reduction ◽  
Average Grain Size ◽  
Cold Rolled

Microstructural evolutions of the 4Al alumina-forming austenitic steel after cold rolling with different reductions from 5% to 30% and then annealing were investigated using electron backscattering diffraction (EBSD), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile properties and hardness were also measured. The results show that the average grain size gradually decreases with an increase in the cold-rolling reduction. The low angle grain boundaries (LAGBs) are dominant in the cold-rolled samples, but high angle grain boundaries (HAGBs) form in the annealed samples, indicating that the grains are refined under the action of dislocations. During cold rolling, high-density dislocations are initially introduced in the samples, which contributes to a large number of dislocations remaining after annealing. With the sustaining increase in cold-rolled deformation, the samples exhibit more excellent tensile strength and hardness due to the decrease in grain size and increase in dislocation density, especially for the samples subjected to 30% cold-rolling reduction. The contribution of dislocations on yield strength is more than 60%.

Influence of high-temperature plastic deformation on the heat resistance of austenitic steel 3Kh19N9MVBT

1967 ◽  
Vol 9 (1) ◽  
pp. 52-55
Author(s):  
N. V. Tikhomirov ◽  
S. A. Skorodumov ◽  
I. G. Generson ◽  
M. N. Snitko ◽  
S. A. Zinov'eva ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Temperature ◽  
Heat Resistance ◽  
Austenitic Steel

Reversible Martensitic Transformation Produced by Severe Plastic Deformation of Metastable Austenitic Steel

2013 ◽  
Vol 738-739 ◽  
pp. 491-495 ◽  
Author(s):  
Igor Litovchenko ◽  
Alexander Tyumentsev ◽  
Alexander V. Korznikov
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Martensitic Transformation ◽  
Severe Plastic Deformation ◽  
Dynamic Recrystallization ◽  
Austenitic Steel ◽  
High Pressure Torsion ◽  
Martensitic Transformations ◽  
Metastable Austenitic Steel ◽  
Nanostructured States

The peculiarities of martensitic transformations and formation of nanostructured states in metastable austenitic steel (Fe-18Cr-8Ni-Ti) after severe plastic deformation by high pressure torsion are investigated. It is shown that during severe plastic deformation with increased strain rate not only direct (γ→α΄) but also reverse (α΄→γ) martensitic transformations occur, which is revealed by the changes in the volume content of α΄ - martensite during deformation. The fragments thought to be formed by direct and reverse martensitic transformations and those of dynamic recrystallization of austenite are observed.

scholarly journals Studying Grain Boundary Strengthening by Dislocation-Based Strain Gradient Crystal Plasticity Coupled with a Multi-Phase-Field Model

2019 ◽  
Author(s):  
Waseem Amin ◽  
Muhammad Adil Ali ◽  
Napat Vajragupta ◽  
Alexander Hartmaier
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Microstructural Evolution ◽  
Crystal Plasticity ◽  
Phase Field ◽  
Strain Gradient ◽  
Mechanical Response ◽  
Functional Dependence ◽  
Initial State ◽  
Computational Materials

One ambitious objective of Integrated Computational Materials Engineering (ICME) is to shorten the materials development cycle by using computational materials simulation techniques at different length scales. In this regard, the most important aspects are the prediction of the microstructural evolution during material processing and the understanding of the contributions of microstructural features to the mechanical response of the materials. One possible solution to such a challenge is to apply the Phase Field (PF) method because it can predict the microstructural evolution under the influence of different internal or external stimuli, including deformation. To accomplish this, it is necessary to take into account plasticity or, specifically, non-homogeneous plastic deformation, which is particularly important for investigating the size effects in materials emerging at the micron length scale. In this work, we present quasi-2D simulations of plastic deformation in a face centred cubic system in a finite strain formulation. Our model consists of dislocation-based strain gradient crystal plasticity implemented into a PF code. We apply this model to study the influence of grain size on the mechanical behavior of polycrystals, which includes dislocation storage and annihilation. Furthermore, the initial state of the material before deformation is also considered. The results show that a dislocation-based strain gradient crystal plasticity model can capture the Hall-Petch effect in many aspects. The model reproduced the correct functional dependence of the flow stress of the polycrystal on grain size without assigning any special properties to the grain boundaries. However, the predicted Hall-Petch coefficients are significantly smaller than those found typically in experiments. In any case, we found a good qualitative agreement between our findings and experimental results.

scholarly journals DIFFUSIVE AND DISPLACIVE PHASE TRANSFORMATIONS UNDER HIGH PRESSURE TORSION

2019 ◽  
Vol 25 (4) ◽  
pp. 230 ◽  
Author(s):  
Boris Straumal ◽  
Askar Kilmametov ◽  
Andrey Mazilkin ◽  
Olga Kogtenkova ◽  
Brigitte Baretzky ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
Phase Composition ◽  
Steady State ◽  
Phase Transformations ◽  
High Pressure Torsion ◽  
Dynamic Equilibrium ◽  
Initial State

<p class="AMSmaintext"><span lang="EN-GB">Severe plastic deformation (SPD) can induce various phase transformations. After a certain strain, the dynamic equilibrium establishes between defects production by an external force and their relaxation (annihilation). The grain size, hardness, phase composition etc. in this steady-state does not depend on the initial state of a material and is, therefore, equifinal. In this review we discuss the competition between precipitation and dissolution of precipitates, amorphization and (nano)crystallization, SPD-induced accelerated mass-transfer, allotropic and martensitic transitions and formation of grain boundary phases.</span></p>

scholarly journals Studying Grain Boundary Strengthening by Dislocation-Based Strain Gradient Crystal Plasticity Coupled with a Multi-Phase-Field Model

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2977 ◽  
Author(s):  
Waseem Amin ◽  
Muhammad Adil Ali ◽  
Napat Vajragupta ◽  
Alexander Hartmaier
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Microstructural Evolution ◽  
Crystal Plasticity ◽  
Phase Field ◽  
Strain Gradient ◽  
Mechanical Response ◽  
Functional Dependence ◽  
Initial State ◽  
Computational Materials

One ambitious objective of Integrated Computational Materials Engineering (ICME) is to shorten the materials development cycle by using computational materials simulation techniques at different length scales. In this regard, the most important aspects are the prediction of the microstructural evolution during material processing and the understanding of the contributions of microstructural features to the mechanical response of the materials. One possible solution to such a challenge is to apply the Phase Field (PF) method because it can predict the microstructural evolution under the influence of different internal or external stimuli, including deformation. To accomplish this, it is necessary to take into account plasticity or, specifically, non-homogeneous plastic deformation, which is particularly important for investigating the size effects in materials emerging at the micron length scale. In this work, we present quasi-2D simulations of plastic deformation in a face centred cubic system using a finite strain formulation. Our model consists of dislocation-based strain gradient crystal plasticity implemented into a PF code. We apply this model to study the influence of grain size on the mechanical behavior of polycrystals, which includes dislocation storage and annihilation. Furthermore, the initial state of the material before deformation is also considered. The results show that a dislocation-based strain gradient crystal plasticity model can capture the Hall-Petch effect in many aspects. The model reproduced the correct functional dependence of the flow stress of the polycrystal on grain size without assigning any special properties to the grain boundaries. However, the predicted Hall-Petch coefficients are significantly smaller than those found typically in experiments. In any case, we found a good qualitative agreement between our findings and experimental results.

Structural Characterization of FeAl28Cr5 Alloy Deformed in the Hot Torsion Process

2016 ◽  
Vol 246 ◽  
pp. 43-46 ◽  
Author(s):  
Iwona Bednarczyk ◽  
Magdalena Jabłońska
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Structural Changes ◽  
Al Alloys ◽  
Dynamic Processes ◽  
Fine Grained ◽  
Average Grain Size ◽  
Fine Grained Structure ◽  
Hot Torsion

Current research in the field of iron aluminides are directed towards to understand the structural phenomena occurring during plastic deformation of these alloys. The obtained results of the study and collected informations will be used to determine the description of the structural changes taking place during hot deformation of Fe ̶Al alloys. The article presents the results of the study of the alloy FeAl28Cr5 deformed by hot torsion in temperature range of 800÷1100°C and a strain rate of 0.1 s-1. The analysis of the structure of the alloy FeAl28Cr5 allowed to reveal changes caused by dynamic processes of deformation. The results of torsion tests show the possibility to obtain a fine-grained structure with of parameters of the processes (T=1000°C, 1100°C) and strain of ε=40. After deformation at strain of (ε=40) the structure consists of fine grains with a misorientation angle higher than 15°, and the average grain size diameter D=28.5 micrometers. Deformation at a temperature of T=1000°C and 1100°C is accompanied by superplastic flow effect.

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