Contribution of deformation mechanisms to strength and ductility in two Cr–Mn grade austenitic stainless steels

Abstract

The role of different deformation mechanisms in controlling mechanical properties were studied in two low-Ni, Cr–Mn austenitic stainless steel grades (Types 201 and 201L) by tensile testing and microstructure examinations. Tensile tests were carried out at two different strain rates, 5×10−4 and 10−2s−1, in the temperature range from −80°C to 200°C. It was observed that the flow properties and work hardening rate are affected significantly by temperature and strain rate for the concerned steels through variation of deformation mechanism. Deformation-induced austenite-to-martensite transformation (TRIP effect) is the dominant mechanism at temperatures below room temperature. From 50°C up to 200°C, plastic deformation is controlled by mechanical twinning (TWIP effect) and dislocation glide. The electron backscattered diffraction (EBSD) technique and transmission electron microscopy (TEM) were employed to study the plastic deformation accommodation and identify the primary deformation mechanisms operating in the deformed steels.