Microstructure and Mechanical Properties of a Duplex Martensite Austenitic Steel Precipitation-hardened by VC Carbide

This paper presents an investigation on the primary microstructure and mechanical properties of a martensite-austenitic duplex steel precipitation-hardened by VC carbide. The results show that the mechanical properties at room temperature are strongly dependent upon the volume fraction of austenite f A . When f A 32%, with increasing the f A , ultimate strength rises and yield strength drops down. Experimental results at elevated temperatures, show that when test temperature ≤ 500°C, the yield strength to modulus ratio remains unchanged, however, as the temperature rises a substantial fall in the ratio occurs. The strength values at 600 and 700°C are increased with increasing strain rate measured by cross-head speed of testing machine. The law of mixtures and the contribution of strain-induced transformation from unstable austenite to martensite to the mechanical properties are discussed