Superplastic Deformation of Ultrafine Grained Al Alloy Processed by ECAP and Post-Rolling

2006 ◽  
Vol 503-504 ◽  
pp. 119-124 ◽  
Author(s):  
Kyung Tae Park ◽  
Chong Soo Lee ◽  
Yong Suk Kim ◽  
Dong Hyuk Shin
Keyword(s):  
Cold Rolling ◽  
Strain Rate ◽  
High Strain ◽  
Grain Boundary Sliding ◽  
Strain Rate Range ◽  
Al Alloy ◽  
Superplastic Behavior ◽  
Ultrafine Grained ◽  
Boundary Sliding ◽  
Main Deformation

Superplastic behavior of an ultrafine grained (UFG) 5154 Al alloy processed by ECAP and cold rolling (ECAP+CR sample) was investigated and compared with that of the alloy processed by only ECAP without rolling (ECAP sample) in the strain rate range of 10-4~5×10-1 s-1 at 723 K. Processing of the ECAP+CR sample consisted of ECAP of 4 passes, which was less than that showing the optimum microstructure for high strain rate superplasticity of UFG Al alloys (i.e. 8 passes), with route Bc and subsequent cold rolling (70% thickness reduction). The superplastic elongation was remarkably enhanced by post-rolling. An analysis of the mechanical data revealed that deformation of the ECAP+CR sample was dominated by grain boundary sliding, but dislocation viscous glide was the main deformation mechanism for the ECAP sample. In addition, cavitation in the ECAP+CR sample was insignificant up to ∼300% elongation.

Tensile Properties and Microstructure of ZK60 Magnesium Alloys at High Temperature

2011 ◽  
Vol 117-119 ◽  
pp. 1113-1116
Author(s):  
Wen Jie Cheng ◽  
Fu Xiao Chen
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
Flow Behavior ◽  
Rate Sensitivity ◽  
Grain Boundary Sliding ◽  
Maximum Elongation ◽  
Superplastic Behavior ◽  
Boundary Sliding ◽  
Zk60 Magnesium Alloy ◽  
Main Deformation

Using tensile test of ZK60 magnesium alloy, the superplastic flow behavior was studied. The deformation temperature was set as 280°C, 310°C,340°C, 370°C and 400°C while strain rate was 1×10-1s-1, 1×10-2s-1, 1×10-3s-1 and 1×10-4s-1. The results showed that the perfect superplastic behavior was presented at 370°C and =1×10-4s-1 and the maximum elongation could be 133.7%. The biggest factor of strain rate sensitivity was 0.62. The microstructure of the fracture was analyzed used SEM and the results showed that the main deformation mechanism of ZK60 magnesium alloy was grain boundary sliding.

Influence of Strain Rate and Strain on the Surface Properties in Superplastically Boronized Duplex Stainless Steel (DSS)

2009 ◽  
Vol 283-286 ◽  
pp. 458-463 ◽  
Author(s):  
N.H. Abd Aziz ◽  
Iswadi Jauhari ◽  
H.A. Mohd Yusof ◽  
Nor Wahida Ahamad
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
Duplex Stainless Steel ◽  
High Strain ◽  
Grain Boundary Sliding ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Compression Strain ◽  
Short Period ◽  
Boundary Sliding

It was reported that superplastic boronizing process (SPB) provides a much faster boronizing rate than the conventional boronizing process (CB). This process was conducted on duplex stainless steel (DSS) which exhibit superplasticity. The study concentrated on the effect of strain rate and compression strain on SPB. The process was conducted under four different strain rates and three diferent strains condition. Boronizing was successfully conducted with the best result obtained under the high strain rate range of 5 x 10-5 s-1 to 1 x 10-3 s-1 which is associated with the superplastic region. Through SPB, movement of atoms into the specimen was highly accelerated by the grain boundary sliding process leading to a formation of thick and hard boronized layer in extraordinarily short period of time.

Superplastic Behavior of As-Equal Channel Angular Pressed 5083 Al and 5083 Al-0.2 Sc Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 2937-2940 ◽  
Author(s):  
Kyung Tae Park ◽  
Chong Soo Lee ◽  
Dong Hyuk Shin
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Al Alloy ◽  
Superplastic Behavior ◽  
Angular Pressing ◽  
Rate Region ◽  
Ultrafine Grained ◽  
Order Of Magnitude ◽  
5083 Al Alloy

An ultrafine grained structure was obtained in the two grades of a 5083 Al alloy with or without scandium by using equal channel angular pressing and its superplastic behavior was characterized. For the alloy without scandium, low temperature superplasticity was obtained but high strain rate superplasticity was unlikely to occur. By contrast, the alloy containing a small amount of scandium exhibited high strain rate superplasticity. It was found that, in both cases, the strain rate region showing superplasticity was very limited, i.e. one order of magnitude. From the mechanical data, the deformation mechanisms were examined.

Extraordinary High Strain Rate Superplasticity of an Al-Mg-Sc-Zr Alloy Subjected to Equal Channel Angular Pressing

2012 ◽  
Vol 735 ◽  
pp. 295-300
Author(s):  
Elena Avtokratova ◽  
Oleg Sitdikov ◽  
Michael Markushev ◽  
Radik R. Mulyukov
Keyword(s):  
Strain Rate ◽  
Equal Channel Angular Pressing ◽  
High Strain ◽  
Strain Rate Range ◽  
Rate Range ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Excess Phases ◽  
Ultrafine Grained Microstructure ◽  
Zr Alloy

Unique superplastic elongations up to 4100% were achieved at 450°C in the strain rate range of 10-2-10-1s-1for Al-Mg-Sc-Zr alloy with a grain size ~1 μm processed by warm-to-hot equal channel angular pressing. Such a behavior is attributed to the synergy of complementary factors resulted in high homogeneity and stability of ultrafine-grained microstructure and superplastic flow, involving large proportion of high-angle grain boundaries, presence of dispersoids of aluminides of transition metals and negligible amount of coarse excess phases.

A Model for the Effects of Strain Rate and Temperature on the Deformation Behavior of Ultrafine-Grained Metals

2011 ◽  
Vol 291-294 ◽  
pp. 1173-1177
Author(s):  
Zi Ling Xie ◽  
Lin Zhu Sun ◽  
Fang Yang
Keyword(s):  
Grain Boundary ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Boundary Diffusion ◽  
Rate Sensitivity ◽  
Grain Boundary Sliding ◽  
Dislocation Slip ◽  
Deformation Response ◽  
Ultrafine Grained ◽  
Boundary Sliding

A theoretical model is developed to account for the effects of strain rate and temperature on the deformation behavior of ultrafine-grained fcc Cu. Three mechanisms, including dislocation slip, grain boundary diffusion, and grain boundary sliding are considered to contribute to the deformation response simultaneously. Numerical simulations show that the strain rate sensitivity increases with decreasing grain size and strain rate, and that the flow stress and tensile ductility increase with either increasing strain rate or decreasing deformation temperature.

Effect of Rolling on Superplastic Behavior of an Al-Mg-Sc Alloy with Ultrafine-Grained Structure

2016 ◽  
Vol 838-839 ◽  
pp. 416-421 ◽  
Author(s):  
Andrii Dubyna ◽  
Sergey Malopheyev ◽  
Rustam Kaibyshev
Keyword(s):  
Cold Rolling ◽  
Strain Rate ◽  
Rolling Direction ◽  
Initial Strain Rate ◽  
Warm Rolling ◽  
Initial Strain ◽  
Superplastic Behavior ◽  
Ultrafine Grained ◽  
Elongation To Failure ◽  
Superplastic Properties

The superplastic behavior of a commercial aluminum alloy denoted as 1570 Al with a chemical composition of Al-6%Mg-0.5%Mn-0.2%Sc-0.07%Zr (in wt. %) and ultrafine-grained (UFG) structure produced by equal channel angular pressing at 300°C to a true strain ~12 was studied after final cold or warm rolling. The tensile specimens were machined along rolling direction and pulled up to failure in the temperature range of 250 to 500°C at strain rates ranging from 10-4 s-1 to 10-1 s-1. The specimens produced by warm or cold rolling exhibit different superplastic behavior. The material subjected to warm rolling exhibits excellent superplastic properties; the highest elongation-to-failure of ~1970% was recorded at a temperature of ~450°C and an initial strain rate of 1.4×10-1 s-1. On the other hand, the material subjected to cold rolling demonstrates moderate superplastic properties; the highest elongation-to-failure of ~755% appears at a temperature of ~300°C and an initial strain rate of 1.4×10-2 s-1.

Strain-Rate Sensitivity Enhanced by Grain-Boundary Sliding in Creep Condition for AZ31 Magnesium Alloy at Room Temperature

2016 ◽  
Vol 838-839 ◽  
pp. 106-109 ◽  
Author(s):  
Tetsuya Matsunaga ◽  
Hidetoshi Somekawa ◽  
Hiromichi Hongo ◽  
Masaaki Tabuchi
Keyword(s):  
Grain Boundary ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
High Strain ◽  
Rate Sensitivity ◽  
Grain Boundary Sliding ◽  
Strain Rates ◽  
High Strain Rates ◽  
Boundary Sliding

This study investigated strain-rate sensitivity (SRS) in an as-extruded AZ31 magnesium (Mg) alloy with grain size of about 10 mm. Although the alloy shows negligible SRS at strain rates of >10-5 s-1 at room temperature, the exponent increased by one order from 0.008 to 0.06 with decrease of the strain rate down to 10-8 s-1. The activation volume (V) was evaluated as approximately 100b3 at high strain rates and as about 15b3 at low strain rates (where b is the Burgers vector). In addition, deformation twin was observed only at high strain rates. Because the twin nucleates at the grain boundary, stress concentration is necessary to be accommodated by dislocation absorption into the grain boundary at low strain rates. Extrinsic grain boundary dislocations move and engender grain boundary sliding (GBS) with low thermal assistance. Therefore, GBS enhances and engenders SRS in AZ31 Mg alloy at room temperature.

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