High Strain Rate Superplasticity and Microstructure Evolution in a Coarse-Grained Mg-Gd-Y-Zr Rolled Sheet

2014 ◽  
Vol 900 ◽  
pp. 719-724
Author(s):  
Ying Zheng ◽  
Chang Ping Tang ◽  
Yun Lai Deng
Keyword(s):  
Electron Microscopy ◽  
Dynamic Recrystallization ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Microstructural Analysis ◽  
Alloy Sheet ◽  
Coarse Grained ◽  
Dislocation Slip ◽  
Rolled Sheet

Superplasticity at high deformation rates is desirable in order to make superplastic forming more practical. High strain rate superplastic behavior and microstructure of the rolled Mg-Gd-Y-Zr alloy sheet were investigated. For the purposes, tensile tests at the strain rate of 0.01 s-1were conducted, which revealed that the sheet exhibited elongations of 180%~266%. Post-deforming microstructures were characterized by optical microscopy, scanning electron microscopy and transmission electron microscopy, while crystallographic orientation information was obtained from macro-texture analysis. The results show that the high strain rate superplasticity was attributed to class-I creep accommodated by dynamic recrystallization. It is suggested from microstructural analysis results that the interaction between second phases and dislocation facilitated dynamic recrystallization. The macro-texture at the strain of 0.8 still exhibited some characteristics of the crystal rotation arising from dislocation slip despite the occurrence of DRX.

Tensile Ductility of Ultra-Fine Grained Copper at High Strain Rate

2010 ◽  
Vol 160-162 ◽  
pp. 260-266 ◽  
Author(s):  
Tao Suo ◽  
Kui Xie ◽  
Yu Long Li ◽  
Feng Zhao ◽  
Qiong Deng
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Testing Machine ◽  
Coarse Grained ◽  
Dislocation Dynamic ◽  
Pressing Method ◽  
Fine Grained ◽  
Angular Pressing ◽  
Split Hopkinson

In this paper, ultra-fine grained copper fabricated by equal channel angular pressing method and annealed coarse grained copper were tensioned under both quasi-static and dynamic loading conditions using an electronic universal testing machine and the split Hopkinson tension bar respectively. The rapture surface of specimen was also observed via a Scanning Electron Microscope (SEM). The experimental results show that the ductility of polycrystalline copper decreases remarkably due to the grain refinement. However, with the increase of applied strain rate, ductility of the UFG-Cu is enhanced. The fracture morphologies also give the evidence of enhanced ductility of UFG-Cu at high strain rate. It is believed the enhanced ductility of UFG materials at high strain rate can be attributed to the restrained dislocation dynamic recovery.

scholarly journals Dynamic Recrystallization During High-Strain-Rate Tension of Copper

2016 ◽  
Vol 47 (6) ◽  
pp. 2555-2559 ◽  
Author(s):  
Nooshin Mortazavi ◽  
Nicola Bonora ◽  
Andrew Ruggiero ◽  
Magnus Hörnqvist Colliander
Keyword(s):  
Dynamic Recrystallization ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain

scholarly journals Study of the Dynamic Recrystallization Process of the Inconel625 Alloy at a High Strain Rate

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 510 ◽  
Author(s):  
Zhi Jia ◽  
Zexi Gao ◽  
Jinjin Ji ◽  
Dexue Liu ◽  
Tingbiao Guo ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Volume Fraction ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
True Strain ◽  
Recrystallization Process ◽  
Compression Process

High-temperature compression and electron backscatter diffraction (EBSD) techniques were used in a systematic investigation of the dynamic recrystallization (DRX) behavior and texture evolution of the Inconel625 alloy. The true stress–true strain curves and the constitutive equation of Inconel625 were obtained at temperatures ranging from 900 to 1200 °C and strain rates of 10, 1, 0.1, and 0.01 s−1. The adiabatic heating effect was observed during the hot compression process. At a high strain rate, as the temperature increased, the grains initially refined and then grew, and the proportion of high-angle grain boundaries increased. The volume fraction of the dynamic recrystallization increased. Most of the grains were randomly distributed and the proportion of recrystallized texture components first increased and then decreased. Complete dynamic recrystallization occurred at 1100 °C, where the recrystallized volume fraction and the random distribution ratios of grains reached a maximum. This study indicated that the dynamic recrystallization mechanism of the Inconel625 alloy at a high strain rate included continuous dynamic recrystallization with subgrain merging and rotation, and discontinuous dynamic recrystallization with bulging grain boundary induced by twinning. The latter mechanism was less dominant.

Research on Flow Stress of Magnesium Alloy Sheet under Warm and High Strain Rate Forming Condition

2011 ◽  
Vol 189-193 ◽  
pp. 2522-2525
Author(s):  
Zheng Hua Meng ◽  
Shang Yu Huang ◽  
Jian Hua Hu
Keyword(s):  
Flow Stress ◽  
Magnesium Alloy ◽  
High Strain Rate ◽  
Strain Rate ◽  
Process Simulation ◽  
High Strain ◽  
Alloy Sheet ◽  
Az31 Magnesium Alloy ◽  
Rate Condition ◽  
Magnesium Alloy Sheet

Process simulation is a powerful tool to predict material behaviors under specified deformation conditions, so as to optimize the processing parameters. The equation for flow stress is important to numerically analyze. However, the reported constitutive equations of magnesium alloy are only suitable for processing simulation with strain rate between 0.001-1s-1. In this paper, the strain-stress behavior of AZ31 under warm and high strain rate (>103s-1) condition has been investigated by split Hopkinson pressure bar experiments at elevated temperature. The results show that the influence of the temperature on flow stress is more obvious than that of strain rate; the flow stress decreases with the rise of temperature at a certain strain rate. Based on Johnson-Cook model, the constitutive equation of AZ31 magnesium alloy under warm and high strain rate condition has been given out by fitting the experimental data, which can be applied in process simulation of AZ31 magnesium alloy sheet forming.

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