Effects of austenitizing temperature on microstructure and mechanical property of a 4-GPa-grade PM high-speed steel

Effects of austenitizing temperature on the microstructure and mechanical property of a high-strength PM high-speed steel were systematically investigated using a series of heat treatments in the temperature range of 1070-1180 °C. Results showed that the optimal austenitizing temperature to obtain the desired combination of high compressive strength of 3838 MPa and high ductility of 29.7%, the optimal austenitizing temperature was 1180 °C. A maximum strength of 3870 MPa and a fracture strain of 22.7% was obtained by austenitized at 1120 °C. It is evident that the size distribution and carbide contents of both VC and Fe3W3C can be significantly changed by heat treatment and triple tempering resulted in slight decline in the amount of cracked carbides. Fractography showed that more broken particles of Fe3W3C carbide was observed than that of the VC particles in fractured specimens.