Norio Furushiro1, Yoshimasa Takayama2, Tatsumi Tozawa2, Hajime Kato2 and Kazuto Ono2
1Department of Materials Science and Engineering, Faculty of Engineering, Osaka University, Suita
In order to evaluate the basic characteristics of superplastic materials, an R-type specimen has been proposed, which has no ordinary gauge part of a uniform cross section.
First, the fundamental problems of a conventional evaluation method have been pointed out. Then, the superplastic characteristics of a Zn--Al eutectoid superplastic alloy have been examined to investigate the possibility of the new evaluation method using the R-type specimen.
As a result, it is found that the R-type specimen has the excellent possibility. In particular, the extremely high elongation can be estimated from a peak value of strain distribution after fracture. Moreover, true stress versus true strain rate relation and m-value in a wide range of strain rate can be derived from the results for a pair of R-type specimens.
(Received July 6, 1992)
superplasticity, evaluation, R-type specimen, tensile test, zinc--aluminum eutectoid alloy
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