Dynamic Recrystallization under Warm and Hot Deformation of a 304 Stainless Steel

摘要

Deformation behaviour and structure evolution of 304 type austenitic stainless steel were studied by multiple compression tests at temperatures of 873 to 1223K ( 0.5 - 0.7 T_m). The deformation behaviour in the region of flow stresses less than around 400 MPa is typical for hot working accompanied with conventional dynamic recrystallization. In contrast, the deformation behaviour under higher stresses above 400 MPa is characterised by weak strain rate and temperature dependence and so may be in an athermal deformation region. The multiple deformation even in the athermal region results in the evolution of fine grained structures at severe cumulative strains. The dynamic grain size evolved can be expressed by a power law equation with a grain size exponent of about -0.4, which is different from that of -0.7 for hot deformation. It is concluded that new grains can be developed by continuous dynamic recrystallization under warm deformation.