DEVELOPMENT OF MULTILEVEL MODELS BASED ON CRYSTAL PLASTICITY: DESCRIPTION OF GRAIN BOUNDARY SLIDING AND EVOLUTION OF GRAIN STRUCTURE

2015 ◽  
Vol 6 (4) ◽  
pp. 281-298 ◽  
Author(s):  
A. I. Shveykin ◽  
E. R. Sharifullina
Keyword(s):  
Grain Boundary ◽  
Crystal Plasticity ◽  
Multilevel Models ◽  
Grain Boundary Sliding ◽  
Grain Structure ◽  
Boundary Sliding

Direct Observation of Two-Dimensional Grain Boundary Sliding and Switching in ODS Ferritic Steel

2016 ◽  
Vol 838-839 ◽  
pp. 43-50
Author(s):  
Eiichi Sato ◽  
Hiroshi Masuda ◽  
Yoshito Sugino ◽  
Shigeharu Ukai
Keyword(s):  
Grain Boundary ◽  
Ferritic Steel ◽  
Tensile Deformation ◽  
Grain Boundary Sliding ◽  
Grain Structure ◽  
Two Dimensional ◽  
Kernel Average Misorientation ◽  
Boundary Sliding ◽  
High Temperature Tensile ◽  
Region Ii

High-temperature tensile deformation was performed using an oxide-dispersionstrengthened (ODS) ferritic steel,, which has grain structure largely elongated and aligned in one direction, in the perpendicular direction. In the superplastic region II, two-dimensional grain boundary sliding (GBS) was achieved, in which the material did not shrink in the grain-axis direction and grain-boundary steps appeared only in the surface perpendicular to the grain axis. In this condition, a classical grain switching event was observed. Using kernel average misorientation maps drawn with SEM/EBSD, dominant deformation mechanisms and accommodation processes for GBS were examined in the different regions. Cooperative grain boundary sliding, in which only some of grain boundaries slide, was also observed.

scholarly journals Statistical Crystal Plasticity Model Advanced for Grain Boundary Sliding Description

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 822
Author(s):  
Alexey Shveykin ◽  
Peter Trusov ◽  
Elvira Sharifullina
Keyword(s):  
Grain Boundary ◽  
Constitutive Model ◽  
Grain Boundaries ◽  
Crystal Plasticity ◽  
Inelastic Deformation ◽  
Grain Boundary Sliding ◽  
Lattice Rotation ◽  
Mutual Arrangement ◽  
Structural Level ◽  
Boundary Sliding

Grain boundary sliding is an important deformation mechanism, and therefore its description is essential for modeling different technological processes of thermomechanical treatment, in particular the superplasticity forming of metallic materials. For this purpose, we have developed a three-level statistical crystal plasticity constitutive model of polycrystalline metals and alloys, which takes into account intragranular dislocation sliding, crystallite lattice rotation and grain boundary sliding. A key advantage of our model over the classical Taylor-type models is that it also includes a consideration of grain boundaries and possible changes in their mutual arrangement. The constitutive relations are defined in rate form and in current configuration, which makes it possible to use additive contributions of intragranular sliding and grain boundary sliding to the strain rate at the macrolevel. In describing grain boundary sliding, displacements along the grain boundaries are considered explicitly, and changes in the neighboring grains are taken into account. In addition, the transition from displacements to deformation (shear) characteristics is done for the macrolevel representative volume via averaging, and the grain boundary sliding submodel is attributed to a separate structural level. We have also analyzed the interaction between grain boundary sliding and intragranular inelastic deformation. The influx of intragranular dislocations into the boundary increases the number of defects in it and the boundary energy, and promotes grain boundary sliding. The constitutive equation for grain boundary sliding describes boundary smoothing caused by diffusion effects. The results of the numerical experiments are in good agreement with the known experimental data. The numerical simulation demonstrates that analysis of grain boundary sliding has a significant impact on the results, and the multilevel constitutive model proposed in this study can be used to describe different inelastic deformation regimes, including superplasticity and transitions between conventional plasticity and superplasticity.

scholarly journals Using High-Pressure Torsion to Achieve Superplasticity in an AZ91 Magnesium Alloy

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 681 ◽  
Author(s):  
Roberto B. Figueiredo ◽  
Terence G. Langdon
Keyword(s):  
High Pressure ◽  
Magnesium Alloy ◽  
Grain Boundary ◽  
High Pressure Torsion ◽  
Grain Boundary Sliding ◽  
Grain Structure ◽  
Strain Rates ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium ◽  
Boundary Sliding

An AZ91 magnesium alloy (Mg-9%, Al-1% Zn) was processed by high-pressure torsion (HPT) after solution-heat treatment. Tensile tests were carried out at 423, 523, and 623 K in the strain rate range of 10−5−10−1 s−1 to evaluate the occurrence of superplasticity. Results showed that HPT processing refined the grain structure in the alloy, and grain sizes smaller than 10 µm were retained up to 623 K. Superplastic elongations were observed at low strain rates at 423 K and at all strain rates at 523 K. An examination of the experiment data showed good agreement with the theoretical prediction for grain-boundary sliding, the rate-controlling mechanism for superplasticity. Elongations in the range of 300–400% were observed at 623 K, attributed to a combination of grain-boundary-sliding and dislocation-climb mechanisms.

scholarly journals Crystal plasticity based modeling of grain boundary sliding in magnesium alloy AZ31B sheet

2021 ◽  
Vol 31 (1) ◽  
pp. 138-155
Author(s):  
Zi-han LI ◽  
Guo-wei ZHOU ◽  
Da-yong LI ◽  
Hua-miao WANG ◽  
Wei-qin TANG ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Grain Boundary ◽  
Crystal Plasticity ◽  
Grain Boundary Sliding ◽  
Magnesium Alloy Az31b ◽  
Boundary Sliding

Effect of Rare Earth Yttrium on the Hot Ductility of Fe-36Ni Invar Alloy

2014 ◽  
Vol 33 (6) ◽  
pp. 531-537 ◽  
Author(s):  
Y. C. Yu ◽  
H. T. Liu ◽  
W. Q. Chen ◽  
H. G. Zheng
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Testing Temperature ◽  
Grain Boundary Sliding ◽  
Substantial Improvement ◽  
Grain Structure ◽  
Invar Alloy ◽  
Hot Ductility ◽  
Temperature Range ◽  
Boundary Sliding

AbstractThe hot ductility of Fe-36Ni invar alloy doped with and without yttrium was investigated using a Gleeble-3800 thermal-mechanical simulator over the temperature range 850–1050 °C and the improvement mechanism of the hot ductility was analysed with a combination of SEM, EDS and OM. The results showed that Fe-36Ni invar alloy had a poor hot ductility below 1050 °C, which was mainly attributed to the presence of the grain boundary sliding and weak grain boundaries. The addition of 0.048% yttrium had a substantial improvement in the hot ductility of Fe-36Ni invar alloy over the whole testing temperature range especially at 950–1000 °C. At 850–900 °C, the improvement of the hot ductility was mainly associated with the grain boundary strengthening and the restriction of the grain boundary sliding because the addition of yttrium could reduce the segregation of sulfur at grain boundaries and refine the grain structure. At 950–1000 °C, the hot ductility was highly improved, which was owed to the acceleration and occurrence of dynamic recrystallization as a result of the refinement of the grain structure by addition of yttrium.

Sign in / Sign up

Export Citation Format

Share Document