On the low temperature deformation behavior of a warm rolled 304L-type stainless steel

Abstract

The deformation behavior of a warm rolled 304L-type austenitic stainless steel was studied by means of tensile tests at temperatures of 213 – 293 K. The starting material was subjected to warm rolling to a strain of 0.5 at 573 K. This warm working promoted the α'-martensite formation upon subsequent tensile tests at lowered temperatures owing to shortening the transformation critical strain. The fraction of α'-martensite comprised more than 0.2 after tension to a strain of 0.3 at 293 K, whereas that was above 0.8 at 213 K. Moreover, the cold deformation was accompanied by twinning and the development of strain-induced grain boundaries leading to submicrocrystalline microstructure evolution. The deformation behavior during tensile tests was characterized by a rapid increase in the flow stress in the strain range of 0.1 – 0.25 that was more pronounced at a lower temperature. The tensile flow stress could be related to the dislocation density, which in turn can be expressed by a function of strain, taking into account the grain subdivision by strain-induced boundaries and martensitic transformation.