Structure and properties of a hypoeutectic chromium steel processed in the semi-solid state

Because of their great hardness and wear resistance, hypoeutectic ledeburitic chromium steels are widely used for machining and measuring tools. Such steels are normally shaped by chipping procedures, and subsequently hardened and tempered. Here we describe the structure and property evolution when an alternative shaping method, net-shape forming in the semi-solid state, is applied. The structure of the material in the as-formed, fast-cooled untempered condition is relatively soft and is characterized by a “nonmagnetic” dual-phase mixture of primary metastable austenite and M7C3-carbide/austenite eutectic. Reduced cooling rates or isothermal aging result in complex multiphase microstructures with great hardness (up to 800 HV10) and wear resistance.