Effect of Niobium and Titanium on the Dynamic Recrystallization during Hot Deformation of Stabilized Ferritic Stainless Steels

2004 ◽  
Vol 467-470 ◽  
pp. 1229-1236 ◽  
Author(s):  
Tarcisio R. Oliveira ◽  
Frank Montheillet
Keyword(s):  
Dynamic Recrystallization ◽  
Stainless Steels ◽  
Hot Deformation ◽  
Boundary Migration ◽  
Solute Drag ◽  
Shear Direction ◽  
Ferritic Stainless Steels ◽  
Solid Solution Strengthening ◽  
Continuous Dynamic Recrystallization ◽  
Continuous Dynamic

The study was carried out to understand the mechanisms occurring during dynamic recrystallization of hot deformed 11% chromium stabilized ferritic stainless steels and to compare the behaviour induced by various types of stabilization. It was observed that continuous dynamic recrystallization (CDRX) operates in all materials starting at the onset of straining. Niobium has a more pronounced influence on hardening than titanium during hot deformation, which is due to solid solution strengthening and also to the reduction or stopping of grain boundary migration by solute drag effect. The D2 component, { 2 1 1 }<111>, was found as the major texture component at the steady state for the torsion tests carried along the negative shear direction. It was likely to be formed by the combination of straining and growth of the grains exhibiting both low stored energy and low rotation rate of the crystallographic axes.

scholarly journals Review on Dynamic Recrystallization of Martensitic Stainless Steels during Hot Deformation: Part I—Experimental Study

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 572
Author(s):  
Hamed Aghajani Derazkola ◽  
Eduardo García Gil ◽  
Alberto Murillo-Marrodán ◽  
Damien Méresse
Keyword(s):  
Dynamic Recrystallization ◽  
Stainless Steels ◽  
Hot Deformation ◽  
Large Strains ◽  
Microstructural Changes ◽  
Ultrafine Grains ◽  
Microstructure Changes ◽  
Continuous Dynamic Recrystallization ◽  
Martensitic Stainless Steels ◽  
Continuous Dynamic

The evolution of the microstructure changes during hot deformation of high-chromium content of stainless steels (martensitic stainless steels) is reviewed. The microstructural changes taking place under high-temperature conditions and the associated mechanical behaviors are presented. During the continuous dynamic recrystallization (cDRX), the new grains nucleate and growth in materials with high stacking fault energies (SFE). On the other hand, new ultrafine grains could be produced in stainless steel material irrespective of the SFE employing high deformation and temperatures. The gradual transformation results from the dislocation of sub-boundaries created at low strains into ultrafine grains with high angle boundaries at large strains. There is limited information about flow stress and monitoring microstructure changes during the hot forming of martensitic stainless steels. For this reason, continuous dynamic recrystallization (cDRX) is still not entirely understood for these types of metals. Recent studies of the deformation behavior of martensitic stainless steels under thermomechanical conditions investigated the relationship between the microstructural changes and mechanical properties. In this review, grain formation under thermomechanical conditions and dynamic recrystallization behavior of this type of steel during the deformation phase is discussed.

Analysis of Large Strain Hot Torsion Textures Associated With “Continuous” Dynamic Recrystallization

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
S. M. Lim ◽  
C. Desrayaud ◽  
F. Montheillet
Keyword(s):  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Large Strain ◽  
Texture Evolution ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Shear Direction ◽  
Continuous Dynamic Recrystallization ◽  
Hot Torsion ◽  
Continuous Dynamic

The development of ideal orientations within the steady-state region of hot torsion flow curves of fcc and bcc metals undergoing “continuous” dynamic recrystallization is analyzed. It is well known that in fcc metals, e.g., Al deformed at 400°C and above, the experimentally observed end texture consists of the twin-symmetric B(112¯)[11¯0]/B¯(1¯1¯2)[1¯10] component, whereby the (hkl)[uvw] indices correspond to the shear plane z and the shear direction θ, respectively. In bcc iron however, only one of the self-symmetric D1(112¯)[111] and D2(1¯1¯2)[111] components dominates (the former in the case of positive shear or clockwise rotation about the r-axis, and the latter during negative shear). The tendency toward a single end orientation imposes certain limitations on grain refinement, as this would ultimately imply the coalescence of subgrains of or close to this orientation, and therefore the disappearance of existing high angle boundaries (≥15 deg). It is believed that the preference of D1 over D2, or vice versa, could be related to phenomena other than glide-induced rotations, e.g., grain boundary migration resulting from differences in work hardening rates. In this paper, the standard Taylor model is first used to predict the texture evolution in simple shear under the full-constraint rate-sensitive scheme. This is then coupled with an approach that takes into account grain boundary migration resulting from differences in dislocation densities within grains of varying orientations. The preliminary results are in agreement with experimental findings, i.e., grains with initial orientations close to D2 grow at the expense of neighboring grains during negative shear and vice versa.

Texture Evolution during Direct and Reversed Hot Torsion Tests of Stabilized Ferritic Stainless Steels

2005 ◽  
Vol 495-497 ◽  
pp. 477-482 ◽  
Author(s):  
Tarcisio R. Oliveira ◽  
Frank Montheillet
Keyword(s):  
Texture Component ◽  
Stainless Steels ◽  
Volume Fraction ◽  
Texture Evolution ◽  
Boundary Migration ◽  
Solute Drag ◽  
Shear Direction ◽  
Ferritic Stainless Steels ◽  
Simplified Approach ◽  
Hot Torsion

The study was carried out to understand the mechanisms occurring during the direct (negative shear direction) and reversed (positive shear direction) hot torsion of 11% chromium stabilized ferritic stainless steels. The behaviours induced by various types of stabilization, i.e., when either niobium, or titanium, or both niobium and titanium are used were compared. It was observed that continuous dynamic recrystallization (CDRX) operates in all materials starting at the onset of straining. Niobium has a more pronounced influence on hardening than titanium during hot deformation, which is due to solid solution strengthening and also to the reduction or stopping of grain boundary migration by solute drag effect. The D2 component, {112} < 111 > , was the major texture component at the steady state for the torsion tests carried along the negative shear direction. It was likely to be formed by a combination of strain and the growth of grains exhibiting both low stored energy and low rotation rate of the crystallographic axes. After reversion of the shear direction, i.e. during positive shear, the above major texture component is gradually changed into the D1 component, {112} < 111 > . Using the CMTP method (Continuum Mechanics of Textured Polycrystals), the stress evolution is explained by the volume fraction changes of each component at various strains, associated with their respective Taylor factors. Such simplified approach leads to a good agreement with experimental results.

scholarly journals Investigation on Sub-Solvus Recrystallization Mechanisms in an Advanced γ-γ’ Nickel-Based Superalloy GH4151

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4553
Author(s):  
Shaomin Lv ◽  
Jinbin Chen ◽  
Xinbo He ◽  
Chonglin Jia ◽  
Kang Wei ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Energy Surface ◽  
Electron Backscatter Diffraction ◽  
True Strain ◽  
Continuous Dynamic Recrystallization ◽  
Nickel Based Superalloy ◽  
Transmission Electron ◽  
Continuous Dynamic ◽  
Backscatter Diffraction

Sub-solvus dynamic recrystallization (DRX) mechanisms in an advanced γ-γ’ nickel-based superalloy GH4151 were investigated by isothermal compression experiments at 1040 °C with a strain rate of 0.1 s−1 and various true strain of 0.1, 0.3, 0.5, and 0.7, respectively. This has not been reported in literature before. The electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) technology were used for the observation of microstructure evolution and the confirmation of DRX mechanisms. The results indicate that a new dynamic recrystallization mechanism occurs during hot deformation of the hot-extruded GH4151 alloy. The nucleation mechanism can be described as such a feature, that is a primary γ’ (Ni3(Al, Ti, Nb)) precipitate embedded in a recrystallized grain existed the same crystallographic orientation, which is defined as heteroepitaxial dynamic recrystallization (HDRX). Meanwhile, the conventional DRX mechanisms, such as the discontinuous dynamic recrystallization (DDRX) characterized by bulging grain boundary and continuous dynamic recrystallization (CDRX) operated through progressive sub-grain merging and rotation, also take place during the hot deformation of the hot-extruded GH4151 alloy. In addition, the step-shaped structures can be observed at grain boundaries, which ensure the low-energy surface state during the DRX process.

Effect of Initial Grain Size on Deformation Behavior and Dynamic Recrystallization of Magnesium Alloy AZ31

2005 ◽  
Vol 488-489 ◽  
pp. 223-226 ◽  
Author(s):  
Xu Yue Yang ◽  
Masayoshi Sanada ◽  
Hiromi Miura ◽  
Taku Sakai
Keyword(s):  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Grain Refinement ◽  
Hot Deformation ◽  
Structural Changes ◽  
Kink Bands ◽  
Alloy Az31 ◽  
Continuous Dynamic Recrystallization ◽  
Magnesium Alloy Az31 ◽  
Continuous Dynamic

Hot deformation and associated structural changes were studied in compression of a magnesium alloy AZ31 with initial grain sizes (D0) of 22 µm and 90 µm at a temperature of 573K. D0 influences significantly the flow curve and the kinetics of grain refinement during hot deformation. For D0 = 22 µm, grain fragmentation takes place due to frequent formation of kink bands initially at corrugated grain boundaries and then in grain interiors in low strain, followed by full development of new fine grains in high strain. For D0 = 90 µm, in contrast, twinning takes place in coarser original grains, and then kink bands and new fine grains are formed mainly in finer ones at low strains. Then new grains are formed in necklace along the boundaries of coarse original grains, followed by their development into the grain interiors. Grain refinement in the Mg alloy can be concluded to result from a series of deformation-induced continuous reactions, they are essentially similar to continuous dynamic recrystallization (cDRX).

Continuous Dynamic Recrystallization during Warm Deformation of Tempered Lath Martensite in a Medium Carbon Steel

2012 ◽  
Vol 508 ◽  
pp. 124-127 ◽  
Author(s):  
Un Hae Lee ◽  
Naoya Kamikawa ◽  
Goro Miyamoto ◽  
Tadashi Furuhara
Keyword(s):  
Dynamic Recrystallization ◽  
Microstructural Evolution ◽  
Boundary Migration ◽  
Lath Martensite ◽  
Medium Carbon Steel ◽  
Warm Deformation ◽  
Continuous Dynamic Recrystallization ◽  
Dynamic Recrystallization Behavior ◽  
Fine Grained Structure ◽  
Continuous Dynamic

To Understand the Mechanisms of Accelerated Dynamic Recrystallization Behavior during the Warm Deformation of Martensites, the Tempered Lath Martensite of 0.4C Steel (Fe-0.399%C-1.96%Mn in Mass %) Was Deformed at 650 °C in Compression to Different Reductions, and Microstructural Evolution Was Investigated. During the Deformation, an Initial Lath Martensite Structure with a Complicated Morphology Was Gradually Changed into More Equiaxed Structure. After 50% Reduction and above, an Equiaxed, Fine Grained Structure Mainly Surrounded by High-Angle Boundaries Was Uniformly Formed with Dislocation Substructures, where the Dislocation Density in the Grains Is Relatively Low. Since there Was No Significant Boundary Migration during this Process, this Microstructural Evolution Can Be Termed as Continuous Dynamic Recrystallization.

scholarly journals A Physically Based Constitutive Model and Continuous Dynamic Recrystallization Behavior Analysis of 2219 Aluminum Alloy during Hot Deformation Process

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1443 ◽  
Author(s):  
Lei Liu ◽  
Yunxin Wu ◽  
Hai Gong ◽  
Shuang Li ◽  
A. S. Ahmad
Keyword(s):  
Constitutive Model ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Flow Behavior ◽  
Large Strains ◽  
Al Alloy ◽  
Continuous Dynamic Recrystallization ◽  
Physically Based ◽  
Continuous Dynamic

The isothermal compression tests of the 2219 Al alloy were conducted at the temperature and the strain rate ranges of 623–773 K and 0.01–10 s−1, respectively, and the deformed microstructures were observed. The flow curves of the 2219 Al alloy obtained show that flow stress decreases with the increase in temperature and/or the decrease in strain rate. The physically based constitutive model is applied to describe the flow behavior during hot deformation. In this model, Young’s modulus and lattice diffusion coefficient are temperature-dependent, and the creep exponent is regarded as a variable. The predicted values calculated by the constitutive model are in good agreement with the experimental results. In addition, it is confirmed that the main softening mechanism of the 2219 Al alloy during hot deformation is dynamic recovery and incomplete continuous dynamic recrystallization (CDRX) by the analysis of electron backscattered diffraction (EBSD) micrographs. Moreover, CDRX can readily occur under the condition of high temperatures, low strain rates, and large strains. Meanwhile, the recrystallization grain size will also be larger.

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