Reliability of Experimental Values for Work-Hardening and Recovery Rates in Pure Aluminum during High Temperature Deformation

In order to clarify the origin of considerable discrepancies among the reports on the work-hardening rate without dynamic restoring effect, h, and the softening rate without work-hardening effect, r, the two parameters have been measured by three different techniques; stress change, strain rate change and stress relaxation tests. These techniques have been applied to high-temperature steady-state deformation of pure aluminum specimens with the same production history, and it has been examined whether the discrepancies come from the difference in production history or the difference in experimental technique.It is found that h values for the same deformation state agree with one another within 30 per cent and r values within 20 per cent. The differences are much smaller than those found among the reports.It is concluded that the disagreements found in the previous reports are caused not by the difference in test technique but by the difference in production history of specimens.