Flow stress equation with effect of strain-rate and temperature histories under processing

The effects of strain, strain-rate, temperature on the now stress variation of some metals are experimentally discussed by using the modified Hopkinso n bar type impact testing machine. It is found through the test that now st ress is greatly affected by both histories of temperature and strain rate. In order to obtain a now stress including the both effects under deformatio n, a reference stress is proposed. The reference stress is defined as the y ield stress under the reference condition. The reference stress is defined by only generalized deformation energy, which is accumulated by plastic def ormation and annihilated by annealing. The new practically useful now-stres s equation is proposed, in which the reference sti ess, strain-rate and tem perature but total strain are included. The proposed now-stress equation is applied to deformation process with varying condition and compared with ex perimental results.