Microstructure characterization of Cu-rich B2 intermetallic nanoprecipitates in an austenite-based High specific strength steel

Abstract

Effects of Cu addition on microstructure and tensile property of a hot rolled austenite-based high specific strength (i.e. yield strength-to-mass density ratio) steel (HSSS) are investigated. The addition of Cu promotes the precipitation of intermetallic compounds (B2), resulting in higher volume fraction of nanoscale B2 particles in the steel. Addition of 2.8wt% Cu improves both the yield strength (by 53MPa) and tensile strength (by 138MPa) of the steel, and maintains high ductility. The yield strength enhancement is predominantly attributed to nanoscale B2 intermetallic precipitation. A high number density of ultrafine (2-10nm) B2 and Cu uniformly precipitates in the austenite martrixwith three different types of ultrafine nanoscale particles.