Improvement of high strain rate and room temperature superplasticity in Zn–22Al alloy by two-step equal-channel angular pressing

2015 ◽  
Vol 620 ◽  
pp. 233-240 ◽  
Author(s):  
M. Demirtas ◽  
G. Purcek ◽  
H. Yanar ◽  
Z.J. Zhang ◽  
Z.F. Zhang
2015 ◽  
Vol 830-831 ◽  
pp. 345-349 ◽  
Author(s):  
Elena Avtokratova ◽  
Oleg Sitdikov ◽  
Oksana Mukhametdinova ◽  
Michael Markushev ◽  
S.V.S. Narayana Murty ◽  
...  

The feasibility has been demonstrated for achieving high-strain-rate superplasticity with elongations beyond 2000% in Al-Mg-Sc-Zr alloy with the partially recrystallized structure, produced by warm equal-channel angular pressing to strain of e~3 only. Subsequent alloy ambient temperature rolling up to e~1.6 enhanced the superplastic elongations and moved the optimum of superplasticity toward the higher strain rates.


2008 ◽  
Author(s):  
P. J. Flater ◽  
J. W. House ◽  
J. M. O'Brien ◽  
W. F. Hosford ◽  
Mark Elert ◽  
...  

2010 ◽  
Vol 667-669 ◽  
pp. 891-896
Author(s):  
Yue Cheng Dong ◽  
Igor V. Alexandrov ◽  
Jing Tao Wang

The high-strain-rate response of ultra-fine-grained (UFG) copper fabricated by equal channel angular pressing (ECAP) has been characterized by Split Hopkinson Pressure Bar (SHPB) test and quasi-static compression test has also been performed for comparison here. In the result of quasi-static tests a maximum yield stress equal to 432 MPa has been reached, at the same time the corresponding value turned out to be 995 MPa after a dynamic loading with the strain rate equal to 1700 s-1. It has been demonstrated that the strain rate sensitivity coefficient (m) has enhanced from 0.026 (coarse-grained copper) to 0.037 (UFG copper). Microstructure has indicated a high dislocation density and deformation twins inside the grains formed after a high-strain-rate deformation, which resulted in a high flow stress. The occurrence of a dynamic recrystallization has also been observed in the UFG copper subjected to high-strain-rate deformation. This has become apparent as an accelerated thermal softening and inherent instability typical for the UFG structure. Absence of adiabatic shear bands pointed out that UFG copper can be subjected to a dynamic impact without any fracture.


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