Hot Deformation of 304 Type Austenitic Stainless Steel at High Strain Rates

摘要

The present results lead to the following conclusions: (1) Stress-strain curves at strain rates higher than 50 s~(-1) can be obtained from simple experiments employing mechanical testing such as torsion by adopting a suitable sample radius to length ratio. In the case of type 304 stainless steels, for the maximum strains of 2.0 employed in this work, the prevailing dynamic softening mechanism changed from dynamic recrystallization at strain rates lower than 10 s~(-1) to incipient dynamic recrystallization at 50 s~(-1) to dynamic recovery at 100 s~(-1), for most test temperatures. Nonetheless, a plot of the maximum stress versus Z was fitted by a hyperbolic sine function over the entire range of strain rates used in this work. (2) In spite of change in the prevailing dynamic softening mechanism during the experiments reported in this paper, a suitable correlation was obtained for the maximum stress versus Z for the entire range of strain rates tested. This suggests that an extrapolation of maximum stress values to higher strain rates is feasible, even if the original data were obtained from relatively low strain rate experiments. The implication of this finding is that the present results can be used to obtain values of maximum stresses at rates even higher than 100 s~(-1) as, for instance, those occurring during wire rod finishing rolling.