J. Phys. IV France 10 (2000) Pr9-137-Pr9-142
Flow stress equation with effect of strain-rate and temperature histories under processingT. Shirakashi1 and M. Yoshino2
1 Department of Precision Machinery Engineering, Tokyo Denki University, 2-2 Kandanishiki-cho, Chiyoda-ku, Tokyo 101-8457, Japan
2 Department of Mechano-Aerospace Engineering, Tokyo Institute of Technology, 2-2 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
The effects of strain, strain-rate, temperature on the flow stress variation of some metals are experimentally discussed by using the modified Hopkinson bar type impact testing machine. It is found through the test that flow stress is greatly affected by both histories of temperature and strain rate. In order to obtain a flow stress including the both effects under deformation, a reference stress is proposed. The reference stress is defined as the yield stress under the reference condition. The reference stress is defined by only generalized deformation energy, which is accumulated by plastic deformation and annihilated by annealing. The new practically useful flow-stress equation is proposed, in which the reference stress, strain-rate and temperature but total strain are included. The proposed flow-stress equation is applied to deformation process with varying condition and compared with experimental results.
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