scholarly journals Grain Rotation Accommodated GBS Mechanism for the Ti-6Al-4V Alloy during Superplastic Deformation

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 991
Author(s):  
Junzhou Yang ◽  
Jianjun Wu
Keyword(s):  
Deformation Mechanism ◽  
Superplastic Deformation ◽  
Texture Evolution ◽  
Flow Behavior ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Grain Boundary Sliding ◽  
Grain Rotation ◽  
Boundary Sliding

An investigation of flow behavior and the deformation mechanism for Ti-6Al-4V alloy during the superplastic deformation process is presented in this paper. Constant strain rate tensile tests were performed at 890–950 °C and strain rates of 10−2, 10−3, and 10−4/s. Then, surface observation by Optical Microscope (OM), Scanning Electron Microscopy (SEM), and Electron Back-scattered Diffraction (EBSD) was applied to obtain the microstructure mechanism. With pole figure maps (PF) for α-phase, obvious texture gradually changed in the main deformation direction. For the titanium alloy, the evolution of texture in deformed samples was attributed to grain rotation (GR). Significant grain rearrangement occurred between grains after deformation. A complete grain rotation accommodated grain boundary sliding (GBS) deformation mechanism is proposed, which can explain texture evolution without grain deformation.

Texture Change during Superplastic Deformation in Fine-Grained Magnesium Alloys

2016 ◽  
Vol 838-839 ◽  
pp. 59-65 ◽  
Author(s):  
Hiroyuki Watanabe ◽  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Grain Boundary ◽  
Magnesium Alloys ◽  
Superplastic Deformation ◽  
Longitudinal Direction ◽  
Grain Boundary Sliding ◽  
Dislocation Slip ◽  
Grain Rotation ◽  
Fine Grained ◽  
Texture Change ◽  
Boundary Sliding

Texture change during superplastic deformation was examined and compared in two magnesium alloys with different chemical composition. These alloys were extruded to refine the microstructure. The pre-existing basal texture of both alloys became slightly more random within the bulk probably owing to grain boundary sliding and the accompanying grain rotation. However, the texture changes differed between tensile and compressive deformation along the extrusion (longitudinal) direction. This fact suggests that dislocation slip is important in superplastic deformation. It was concluded that dislocation slip acts primarily as an accommodation mechanism for grain boundary sliding.

scholarly journals Superplastic Tensile Deformation Behavior and Microstructural Evolution of Al–Zn–Mg–Cu Alloy

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 941
Author(s):  
Guangyu Li ◽  
Hua Ding ◽  
Jian Wang ◽  
Ning Zhang ◽  
Hongliang Hou
Keyword(s):  
Grain Boundary ◽  
Microstructural Evolution ◽  
Superplastic Deformation ◽  
Tensile Deformation ◽  
Grain Boundary Sliding ◽  
Recrystallization Process ◽  
Grain Rotation ◽  
Texture Intensity ◽  
Cu Alloy ◽  
Boundary Sliding

The microstructural evolution of the Al–Zn–Mg–Cu alloy during the superplastic deformation process has been studied by high temperature tensile experiment. The superplastic deformation behaviors are investigated under different temperatures of 470 °C, 485 °C, 500 °C, 515 °C and 530 °C, and different strain rates of 3 × 10−4 s−1, 1 × 10−3 s−1, 3 × 10−2 s−1 and 1 × 10−2 s−1. The microstructure observation shows that uniform and equiaxed grains can be obtained by dynamic recrystallization in the initial stage of superplastic deformation. Once the recrystallization process has been finished, the variations of the fraction of high angle boundary, the grain aspect ratio and the Schmid factor are negligible during the superplastic deformation, which shows that the grain boundary sliding and grain rotation are the main deformation mechanisms. The maximum texture intensity decreases compared with the initial microstructure, indicating that grain boundary sliding and grain rotation can weaken the texture, however, the texture intensity increases in the final stage of superplastic deformation, which may be resulted from the stress concentration.

scholarly journals Superplastic Deformation and Dynamic Recrystallization of a Novel Disc Superalloy GH4151

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3667 ◽  
Author(s):  
Shaomin Lv ◽  
Chonglin Jia ◽  
Xinbo He ◽  
Zhipeng Wan ◽  
Xinxu Li ◽  
...  
Keyword(s):  
Activation Energy ◽  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Superplastic Deformation ◽  
Optical Microscope ◽  
Grain Boundary Sliding ◽  
Experimental Conditions ◽  
Average Activation Energy ◽  
Boundary Sliding

The superplastic deformation of a hot-extruded GH4151 billet was investigated by means of tensile tests with the strain rates of 10−4 s−1, 5 × 10−4 s−1 and 10−3 s−1 and at temperatures at 1060 °C, 1080 °C and 1100 °C. The superplastic deformation of the GH4151 alloy was reported here for the first time. The results reveal that the uniform fine-grained GH4151 alloy exhibited an excellent superplasticity and high strain rate sensitivity (exceeded 0.5) under all experimental conditions. It was found that the increase of strain rate resulted in an increased average activation energy for superplastic deformation. A maximum elongation of 760.4% was determined at a temperature of 1080 °C and strain rate of 10−3 s−1. The average activation energy under different conditions suggested that the superplastic deformation with 1 × 10−4 s−1 in this experiment is mainly deemed as the grain boundary sliding controlled by grain boundary diffusion. However, with a higher stain rate of 5 × 10−4 s−1 and 1 × 10−3 s−1, the superplastic deformation is considered to be grain boundary sliding controlled by lattice diffusion. Based on the systematically microstructural examination using optical microscope (OM), SEM, electron backscatter diffraction (EBSD) and TEM techniques, the failure and dynamic recrystallization (DRX) nucleation mechanisms were proposed. The dominant nucleation mechanism of dynamic recrystallization (DRX) is the bulging of original grain boundaries, which is the typical feature of discontinuous dynamic recrystallization (DDRX), and continuous dynamic recrystallization (CDRX) is merely an assistant mechanism of DRX. The main contributions of DRX on superplasticity elongation were derived from its grain refinement process.

Accommodation mechanisms for grain boundary sliding as inferred from texture evolution during superplastic deformation

2013 ◽  
Vol 93 (22) ◽  
pp. 2913-2931 ◽  
Author(s):  
Hiroyuki Watanabe ◽  
Kouhei Kurimoto ◽  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Grain Boundary ◽  
Superplastic Deformation ◽  
Texture Evolution ◽  
Grain Boundary Sliding ◽  
Boundary Sliding

scholarly journals Superplastic Deformation of Al–Cu Alloys after Grain Refinement by Extrusion Combined with Reversible Torsion

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5803
Author(s):  
Kinga Rodak ◽  
Dariusz Kuc ◽  
Tomasz Mikuszewski
Keyword(s):  
Superplastic Deformation ◽  
Intermetallic Phase ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Microstructural Study ◽  
Cu Alloys ◽  
Al2cu Phase ◽  
Phase Size ◽  
Boundary Sliding ◽  
Superplastic Properties

The binary as-cast Al–Cu alloys Al-5%Cu, Al-25%Cu, and Al-33%Cu (in wt %), composed of the intermetallic θ-Al2Cu and α-Al phases, were prepared from pure components and were subsequently severely plastically deformed by extrusion combined with reversible torsion (KoBo) to refinement of α-Al and Al2Cu phases. The extrusion combined with reversible torsion was carried out using extrusion coefficients of λ = 30 and λ = 98. KoBo applied to the Al–Cu alloys with different initial structures (differences in fraction and phase size) allowed us to obtain for alloys (Al-25%Cu and Al-33%Cu), with higher value of intermetallic phase, large elongations in the range of 830–1100% after tensile tests at the temperature of 400 °C with the strain rate of 10−4 s−1. The value of elongation depended on extrusion coefficient and increase, with λ increasing as a result of α-Al and Al2Cu phase refinement to about 200–400 nm. Deformation at the temperature of 300 °C, independently of the extrusion coefficient (λ), did not ensure superplastic properties of the analyzed alloys. A microstructural study showed that the mechanism of grain boundary sliding was responsible for superplastic deformation.

Effect of Hot Rolling Deformation on Superplastic Deformation Behavior of TiNP/2014Al Composite

2011 ◽  
Vol 264-265 ◽  
pp. 90-95
Author(s):  
Hui E Hu ◽  
Liang Zhen
Keyword(s):  
Strain Rate ◽  
Hot Rolling ◽  
Deformation Mechanism ◽  
Deformation Behavior ◽  
Superplastic Deformation ◽  
Grain Boundary Sliding ◽  
Composite Sheet ◽  
Boundary Sliding ◽  
Effect Of Hot Rolling ◽  
Rolling Deformation

1.5 mm, 0.7 mm and 0.3 mm thicknesses TiNP/2014Al composite sheets were obtained by hot rolling deformation carried out on as-extruded TiNP/2014Al composite rod. The effect of hot rolling deformation on high strain rate superplastic deformation behavior of the composite was researched by tensile experiment, OM, and SEM. Results show that 0.7mm thickness TiNP/2014Al composite sheet can gain the maximum elongation of 351% at 818 K and 3.3×10-1 s-1, and the m value is 0.43. The optimum strain rate increases with decreasing thickness of the TiNP/2014Al composite sheets. Flow stress and work hardening ability show contrary change tendency to optimum strain rate. The 0.7 mm thickness TiNP/2014Al composite sheet has medium flow resistance stress and shows excellent stability of plastic flow. Fracture surfaces show that the main superplastic deformation mechanism of the TiNP/2014Al composite includes in grain boundary sliding. Subgrain boundary sliding maybe another superplastic deformation mechanism.

The Effect of Grain Size on Superplastic Deformation of Ti-6Al-4V Alloy

2007 ◽  
Vol 551-552 ◽  
pp. 387-392 ◽  
Author(s):  
Wen Juan Zhao ◽  
Hua Ding ◽  
D. Song ◽  
F.R. Cao ◽  
Hong Liang Hou
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Superplastic Deformation ◽  
Initial Strain Rate ◽  
Deformation Mode ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Transmission Electron ◽  
Grain Growth Model

In this study, superplastic tensile tests were carried out for Ti-6Al-4V alloy using different initial grain sizes (2.6 μm, 6.5μm and 16.2 μm) at a temperature of 920°C with an initial strain rate of 1×10-3 s-1. To get an insight into the effect of grain size on the superplastic deformation mechanisms, the microstructures of deformed alloy were investigated by using an optical microscope and transmission electron microscope (TEM). The results indicate that there is dramatic difference in the superplastic deformation mode of fine and coarse grained Ti-6Al-4V alloy. Meanwhile, grain growth induced by superplastic deformation has also been clearly observed during deformation process, and the grain growth model including the static and strain induced part during superplastic deformation was utilized to analyze the data of Ti-6Al-4V alloy.

An Experimental Study of Cavity Nucleation During Superplastic Deformation

1990 ◽  
Vol 196 ◽  
Author(s):  
Jiang Xinggang ◽  
Cui Jianzhong ◽  
Ma Longxiang
Keyword(s):  
Grain Boundary ◽  
Superplastic Deformation ◽  
Thermomechanical Processing ◽  
High Stress ◽  
High Strength ◽  
Optical Microscope ◽  
Grain Boundary Sliding ◽  
Cavity Nucleation ◽  
High Stress Concentration ◽  
Voltage Electron

ABSTRACTCavity nucleation during superplastic deformation of a high strength aluminium alloy has been studied using a high voltage electron microscope and an optical microscope. The results show that cavities nucleation is due only to superplastic deformation and not to pre-existing microvoids which may be introduced during thermomechanical processing. The main reason for cavity nucleation is the high stress concentration at discontinuties in the plane of the grain boundary due to grain boundary sliding.

Viscous grain-boundary sliding and grain rotation accommodated by grain-boundary diffusion

2005 ◽  
Vol 53 (6) ◽  
pp. 1791-1798 ◽  
Author(s):  
B.-N. Kim ◽  
K. Hiraga ◽  
K. Morita
Keyword(s):  
Grain Boundary ◽  
Boundary Diffusion ◽  
Grain Boundary Sliding ◽  
Grain Boundary Diffusion ◽  
Grain Rotation ◽  
Boundary Sliding
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