An evaluation of fracture properties of type-304 austenitic stainless steel at high deformation rate using the small punch test

摘要

Among stainless steel, type-304 austenitic stainless steel is the most widely used because of high corrosion resistance as well as favourable mechanical properties due to strain-induced martensitic transformation (SIMT). In order to utilize the application of type-304 austenitic stainless steel in dynamic loading condition, the fracture behaviours with the effect of the local distribution of SIMT in the bending deformation using a relatively small specimen need to be investigated. The effect of SIMT as well as thermal softening phenomenon at a high deformation rate has been examined insufficiently and mechanism for rate-sensitivity of fracture-mechanical characteristic is still unclear. In present study, experiment and FE simulations are performed for the SP test at different deflection rates for type-304 austenitic stainless steel. In order to describe the damage and fracture process of materials, a modified version of the Johnson Cook damage model is applied. After confirming the validity of computation, the rate-sensitivity of fracture-mechanical characteristics of the steel is examined at room temperature. In addition, the effects of temperature and SIMT on the force-deflection curve and fracture properties are discussed to clarify the mechanism for an improvement of impact fracture-mechanical characteristics of the steel.