Influence of Cu on Microstructure and Mechanical Properties for an Extremely Low Carbon Steel During Isothermal Process

Abstract

The phase transformation mode, Cu precipitation behavior during isothermal process and their influences on mechanical properties have been comparatively studied in Cu‐free and Cu‐bearing steels. Cu is found to promote massive transformation and shear transformation, and its precipitation occurs during isothermal process. Significant improvements of yield strength by 250 MPa and tensile strength by 290 MPa have been obtained by adding 2.0 wt% Cu at a slight expense of ductility and low temperature toughness. Calculations on the strengthening effect of Cu revealed that about 70% strength increment has been caused by precipitation strengthening effect. The studies on toughening mechanism shows that Cu precipitation is mainly responsible for the deterioration of low temperature toughness.