scholarly journals Characterization and Calculation of the Dynamic Recrystallization Texture in Fe-3.0 Wt.% Si Alloy

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 517
Author(s):  
Guangshuai Shao ◽  
Yuhui Sha ◽  
Xi Chen ◽  
Songtao Chang ◽  
Fang Zhang ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Recrystallization Texture ◽  
Boundary Migration ◽  
Quantitative Relationship ◽  
Deformation Texture ◽  
Taylor Factor ◽  
Compression Tests ◽  
Electron Backscattered Diffraction ◽  
Initial Texture ◽  
Orientation Boundary

High-temperature plane-strain compression tests were performed on Fe-3.0 wt.% Si alloy from 900 °C to 1150 °C at strain rates of 5 s−1 to 1 s−1, and the texture development from different initial textures was investigated by means of electron backscattered diffraction. Dynamic recrystallization occurs by strain-induced boundary migration, and the evolutions of the microstructure and different texture components vary with the initial texture. The critical orientation boundary separating the weakened and enhanced texture components moves with the initial texture, and a quantitative relationship is established to represent the dependence of the critical Taylor factor on the instantaneous texture. A model is proposed to describe the dynamic recrystallization texture by incorporating the oriented nucleation probability with a variable critical Taylor factor. The present work could improve the accuracy of hot deformation texture prediction based on strain-induced boundary migration.

scholarly journals Effect of Trace Magnesium Additions on the Dynamic Recrystallization in Cast Alloy 825 after One-Hit Hot-Deformation

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 36
Author(s):  
Munir Al-Saadi ◽  
Wangzhong Mu ◽  
Christopher N. Hulme-Smith ◽  
Fredrik Sandberg ◽  
Pär G. Jönsson
Keyword(s):  
Service Life ◽  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Cast Alloy ◽  
True Strain ◽  
Peak Strain ◽  
Compression Tests ◽  
Electron Backscattered Diffraction ◽  
Hollomon Parameter ◽  
Test Conditions

Alloy 825 is widely used in several industries, but its useful service life is limited by both mechanical properties and corrosion resistance. The current work explores the effect of the addition of magnesium on the recrystallization and mechanical behavior of alloy 825 under hot compression. Compression tests were performed under conditions representative of typical forming processes: temperatures between 1100 and 1250 °C and at strain rates of 0.1–10 s−1 to a true strain of 0.7. Microstructural evolution was characterized by electron backscattered diffraction. Dynamic recrystallization was found to be more prevalent under all test conditions in samples containing magnesium, but not in all cases of conventional alloy 825. The texture direction ⟨101⟩ was the dominant orientation parallel to the longitudinal direction of casting (also the direction in which the samples were compressed) in samples that contained magnesium under all test conditions, but not in any sample that did not contain magnesium. For all deformation conditions, the peak stress was approximately 10% lower in material with the addition of magnesium. Furthermore, the differences in the peak strain between different temperatures are approximately 85% smaller if magnesium is present. The average activation energy for hot deformation was calculated to be 430 kJ mol−1 with the addition of magnesium and 450 kJ mol−1 without magnesium. The average size of dynamically recrystallized grains in both alloys showed a power law relation with the Zener–Hollomon parameter, DD~Z−n, and the exponent of value, n, is found to be 0.12. These results can be used to design optimized compositions and thermomechanical treatments of alloy 825 to maximize the useful service life under current service conditions. No experiments were conducted to investigate the effects of such changes on the service life and such experiments should now be performed.

Hot Deformation and Dynamic Recrystallization in Titanium Aluminide

2018 ◽  
Vol 941 ◽  
pp. 1391-1396 ◽  
Author(s):  
Nitish Bibhanshu ◽  
Satyam Suwas
Keyword(s):  
Shear Band ◽  
Dynamic Recrystallization ◽  
Titanium Aluminide ◽  
Volume Fraction ◽  
Shear Bands ◽  
Hot Workability ◽  
Compression Tests ◽  
Electron Backscattered Diffraction ◽  
Gamma Titanium Aluminide ◽  
Z Contrast

The hot workability of gamma titanium aluminide alloy, Ti-48Al-2V-2Nb, was assessed in the cast condition through a series of compression tests conducted over a range of temperatures (1000 to 1175 °C) and at the strain rate of 10 S-1. The mechanism of dynamics recrystallization has been investigated from SEM Z-contrast images and from the Electron backscattered diffraction EBSD as well. It has been observed that volume fraction of the recrystallized grains increases with increasing the deformation temperature. The major volume fraction of the recrystallized grains was observed in the shear band which was forming at an angle 45 ̊ with respect to the compression direction. The mechanism of breaking of the laths and the region of the dynamic recrystallization were also investigated from the SEM Z-contrast image and EBSD. The dynamic recrystallization occurred in the region of the broken laths and shear bands. The breaking of the laths was because of the kinking of the lamellae. The shear band, kinked lamellae and dynamic recrystallized region where all investigated simultaneously.

Microstructure and Texture Development in Alpha-Brass Using Repetitive Thermomechanical Processing

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Khaled Al-Fadhalah
Keyword(s):  
Thermomechanical Processing ◽  
Boundary Migration ◽  
Small Strain ◽  
Texture Development ◽  
Grain Boundary Migration ◽  
Compression Tests ◽  
Brass Alloy ◽  
Electron Backscattered Diffraction ◽  
Compression Strain ◽  
Alpha Brass

Repetitive thermomechanical processing (TMP) has been applied to evaluate the effect of compression strain and temperature on microstructure and texture development in an alpha-brass alloy. Two TMP schemes were employed using four cycles of low-strain compression (ε = 0.15) and annealing, and two cycles of medium-strain compression (ε = 0.3) and annealing. Compression tests were conducted at 25, 250, and −100 °C, while annealing was made at 670 °C for 10 min. Examination by electron backscattered diffraction (EBSD) indicated that the low-strain scheme was capable to increase the fraction of Σ3n boundaries (n = 1, 2, and 3) with increasing cycles, producing maximum fraction of 68%. For medium-strain scheme, a drop in the fraction of Σ3n boundaries occurred in cycle 2. Reducing compression temperature lowered the fraction of Σ3n boundaries for low-strain scheme, while it enhanced the formation of Σ3n boundaries for medium-strain scheme. Annealing textures showed that 〈101〉 compression fiber was strongly retained for samples processed by small-strain scheme, while weakening of 〈101〉 fiber accompanied by the formation of 〈111〉 recrystallization fiber occurred for the medium-strain scheme. The results indicate that the increase in strain energy stored during compression, via increasing strain and/or decreasing deformation temperature, is responsible to favor recrystallization twinning over strain-induced grain boundary migration (SIBM). Both mechanisms are important for the formation of Σ3n boundaries. Yet, SIBM is thought to strongly promote regeneration of Σ3n boundaries at higher TMP cycles. This is consistent with the development of microstructure and texture using small-strain scheme.

Microstructure and Texture of Dynamically Recrystallized Copper and Copper – Tin Alloys

2007 ◽  
Vol 550 ◽  
pp. 393-398 ◽  
Author(s):  
D.T. McDonald ◽  
John F. Humphreys ◽  
Pete S. Bate
Keyword(s):  
Dynamic Recrystallization ◽  
Electron Backscatter Diffraction ◽  
Boundary Migration ◽  
Cube Texture ◽  
Solute Drag ◽  
Deformation Texture ◽  
Tin Alloys ◽  
Resolution Electron ◽  
Recrystallized Grain Size ◽  
Backscatter Diffraction

The microstructure and texture in dynamically recrystallized copper and two copper – tin alloys (2wt% and 4.5wt% tin) has been investigated. Specimens were deformed in channel-die plane strain compression to true strains from 0.1 to 1.22 within the temperature range 200°C to 700°C, and the resulting microstructures were investigated with the use of high resolution electron backscatter diffraction (EBSD). Dynamic recrystallization was initiated by the bulging of preexisting high angle grain boundaries (HAGB), and occurred primarily by strain induced boundary migration (SIBM) and twinning. The addition of tin led to an increase in the temperature at which dynamic recrystallization initiated, and furthermore to a smaller dynamically recrystallized grain size. This was attributed to the effects of solute drag causing lower HAGB mobility. Dynamic recrystallization was observed to weaken the deformation texture components of brass and Goss, as well as introduce a cube texture component which generally tended to strengthen with temperature but weaken with increasing tin additions.

Texture Developments during Ferrite Refinement through Deformation-Enhanced Ferrite Transformation and Dynamic Recrystallization in Low Carbon Steel

2005 ◽  
Vol 475-479 ◽  
pp. 165-168 ◽  
Author(s):  
Ping Yang ◽  
Wang Yue Yang ◽  
Zu Qing Sun
Keyword(s):  
Grain Size ◽  
Carbon Steel ◽  
Dynamic Recrystallization ◽  
Recrystallization Texture ◽  
Low Carbon Steel ◽  
Deformation Texture ◽  
Low Carbon ◽  
Ferrite Transformation ◽  
Transformation Texture ◽  
Ferrite Grain Size

Texture evolutions are determined by XRD and EBSD techniques during ferrite refinement through deformation-enhanced ferrite transformation (DEFT) and dynamic recrystallization (DREX). Evidences of transformation texture, deformation texture and recrystallization texture during DEFT are provided and compared with the texture during DREX. The influence of pass-interval during DEFT on texture is illustrated. Results are discussed in terms of the influences of ferrite grain size and deforming temperature.

Deformation Behavior of Mg-7Gd-5Y-1Nd-0.5Zr Alloy during Hot Compression

2014 ◽  
Vol 633-634 ◽  
pp. 108-115
Author(s):  
Ting Li ◽  
Kui Zhang ◽  
Zhi Wei Du ◽  
Jia Wei Yuan ◽  
Xing Gang Li
Keyword(s):  
Activation Energy ◽  
Regression Analysis ◽  
Dynamic Recrystallization ◽  
Apparent Activation Energy ◽  
Deformation Behavior ◽  
Optical Microscope ◽  
Hot Compression ◽  
Avrami Equation ◽  
Compression Tests ◽  
Electron Backscattered Diffraction

The hot deformation behavior of Mg-7Gd-5Y-1Nd-0.5Zr alloy was investigated by compression tests at temperatures of 673 K, 713 K, 753 K, and 793 K and strain rates of 0.001 s-1, 0.01 s-1, 0.1 s-1, and 1s-1. The stress-strain curves exhibit typical dynamic recrystallization behavior with a single peak stress followed by a gradual fall toward a steady-state stress. The apparent activation energy of deformation and constitutive equations for the alloy were determined through regression analysis for conventional hyperbolic sine equation. The apparent activation energy of DRX and dynamic kinetics model for alloy were determined using the regression analysis for Avrami equation. Optical microscope and electron backscattered diffraction were employed to investigate the microstructure evolution of Mg-7Gd-5Y-1Nd-0.5Zr alloy during hot compression. The results suggested that the grain boundary is the main nucleation sites of dynamic recrystallization, and (0001) basal fiber texture has formed during hot compression.

scholarly journals Effect of Ultrasonic-Assisted Casting on Hot Deformation Mechanism and Microstructure of 35CrMo Steel Ingot

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 146
Author(s):  
Qiumei Yang ◽  
Yajun Zhou ◽  
Wei Zhang ◽  
Xun Zhang ◽  
Mengfei Xu
Keyword(s):  
Activation Energy ◽  
Dynamic Recrystallization ◽  
Steel Ingot ◽  
Flow Behavior ◽  
Strain Rates ◽  
Compression Tests ◽  
Electron Backscattered Diffraction ◽  
35Crmo Steel ◽  
Ultrasonic Assisted ◽  
Softening Process

Hot compression tests were performed with strain rates (0.01–10 s−1) and temperatures (850–1150 °C). The power law relationship between the critical stress and critical strain and Zener–Hollomon parameters was determined by θ-σ curves. Microstructure was investigated by electron backscattered diffraction. The results showed that the flow behavior and microstructure of 35CrMo steel was affected by ultrasonic-assisted casting. The activation energy of non-ultrasonic and ultrasonic-assisted 35CrMo steel were 410 ± 9.9 and 386 ± 9.4 kJ/mol, respectively, and the activation energy of ultrasonic-assisted specimens was reduced by 6%. In addition, the ultrasonic-assisted treatment refines the grains to some extent and makes the softening process of ultrasonic-assisted samples progress faster, which promoted the development of dynamic recrystallization and the production of Σ3 boundaries. The discontinuous dynamic recrystallization was the main DRX nucleation mechanism of the 35CrMo steel.

Mechanisms of Dynamic Recrystallization in Coarse Columnar-Grained Cu-Sn-P Alloy

2012 ◽  
Vol 715-716 ◽  
pp. 586-592
Author(s):  
Hiromi Miura ◽  
Masato Watanabe ◽  
Takashi Shirai ◽  
Akihiko Ishibashi
Keyword(s):  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Boundary Migration ◽  
True Strain ◽  
Compression Tests ◽  
Model Sample ◽  
Annealing Twins ◽  
Preferential Nucleation ◽  
Increasing Temperature

Dynamic recrystallization (DRX) behavior in a coarse columnar-grained Cu-0.65Sn-0.025P and Cu-0.025P (mass%) alloys were systematically investigated by compression tests at temperatures between 1073 K and 1253 K and at true strain rates from 2 x 10-4s-1to 2 x 10-1s-1in vacuum. As a model sample, an orientation-controlled bicrystal having [0 1 twist 18oboundary was prepared and also hot deformed. Appearance of the peaks stress, where DRX onsets, was much delayed in Cu-Sn-P alloy compared with that in Cu-0.025P alloy. The onset of DRX was, therefore, obviously impeded by the small addition of Sn to Cu-P. While nucleation of new grains took place almost at random in Cu-Sn-P when strain rate was high enough, it tended to appear more preferentially at grain boundary with decreasing strain rate and with increasing temperature. The most of new grains were annealing twins formed behind the migrating grain boundary. Because grain boundary migration took place more extensively with increasing temperature and with decreasing strain rate, the preferential nucleation at grain boundary became more significant.

Nucleation and Texture Development during Dynamic Recrystallization of Copper

2005 ◽  
Vol 495-497 ◽  
pp. 1195-1200 ◽  
Author(s):  
D.T. McDonald ◽  
John F. Humphreys ◽  
Pete S. Bate
Keyword(s):  
Dynamic Recrystallization ◽  
Electron Backscatter Diffraction ◽  
Boundary Migration ◽  
Deformation Texture ◽  
Texture Development ◽  
Polycrystalline Copper ◽  
High Angle ◽  
Resolution Electron ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Dynamic recrystallization and texture development in polycrystalline copper have been investigated. Specimens were deformed in channel-die plane strain compression to true strains from 0.1 to 0.7 within the temperature range 200°C to 600°C, and the resulting microstructures were investigated with the use of high resolution electron backscatter diffraction (EBSD). Dynamic recrystallization in copper was initiated by the bulging of pre-existing high angle grain boundaries (HAGB), and occurred primarily by strain induced boundary migration (SIBM). Increasing misorientations from parent to dynamically recrystallizing grains indicated the occurrence of lattice rotations within the bulges, leading, in some cases to the formation of a HAGB behind the bulge. Discrimination between recrystallized and deformed components in material which had partially undergone dynamic recrystallization was carried out, followed by texture analysis. This revealed most of the recrystallized material to have orientations close to that of the deformed material, however, some remote orientations were observed which could not be related to the deformation texture by twin or 40° <111> relationships.

scholarly journals Microstructural Evolution and Refinement Mechanism of a Beta–Gamma TiAl-Based Alloy during Multidirectional Isothermal Forging

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2496 ◽  
Author(s):  
Kai Zhu ◽  
Shoujiang Qu ◽  
Aihan Feng ◽  
Jingli Sun ◽  
Jun Shen
Keyword(s):  
Dynamic Recrystallization ◽  
Microstructural Evolution ◽  
Lamellar Microstructure ◽  
Phase Region ◽  
Second Step ◽  
Electron Backscattered Diffraction ◽  
Isothermal Forging ◽  
Continuous Dynamic Recrystallization ◽  
Mixture Phase ◽  
Refinement Mechanism

Multidirectional isothermal forging (MDIF) was used on a Ti-44Al-4Nb-1.5Cr-0.5Mo-0.2B (at. %) alloy to obtain a crack-free pancake. The microstructural evolution, such as dynamic recovery and recrystallization behavior, were investigated using electron backscattered diffraction and transmission electron microscopy methods. The MDIF broke down the initial near-lamellar microstructure and produced a refined and homogeneous duplex microstructure. γ grains were effectively refined from 3.6 μm to 1.6 μm after the second step of isothermal forging. The ultimate tensile strength at ambient temperature and the elongation at 800 °C increased significantly after isothermal forging. β/B2→α2 transition occurred during intermediate annealing, and α2 + γ→β/B2 transition occurred during the second step of isothermal forging. The refinement mechanism of the first-step isothermal forging process involved the conversion of the lamellar structure and discontinuous dynamic recrystallization (DDRX) of γ grains in the original mixture-phase region. The lamellar conversion included continuous dynamic recrystallization and DDRX of the γ laths and bugling of the γ phase. DDRX behavior of γ grains dominated the refinement mechanism of the second step of isothermal forging.

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