Effect of Microstructure on Activation Energy for High Temperature Deformation of SUS316L Austenitic Stainless Steel

The high temperature deformation behavior of SUS316L austenitic stainless steel with a homogeneous and a harmonic structure (HS) was investigated by a compression test. The HS is a heterostructure having a coarse grain structure (Core) embedded in a fine grain network structure (Shell). In the tensile test at room temperature, the HS materials exhibit high strength with high ductility due to the hetero- deformation-induced (HDI) strengthening, i.e., enhanced strain hardening. However, the high temperature deformation behavior of HS and homogeneous specimens is not clear, especially under different strain rates. In the present study, the high temperature deformation behavior of the HS and homogeneous structure SUS316L stainless steel specimens was investigated from the activation energy point of view of the high temperature deformation. As a result, the activation energy mainly depends on the grain size of the specimens under high temperature deformation.