Effects of Quenching Temperature on Microstructure and Mechanical Properties of 75Cr-Mo Wear-resisting Cast Steel

Abstract

In this paper, metallographic structures, hardness, wear resistance, impact toughness and impact fractures were adopted to study effects of different quenching methods (air cooling + fog cooling) and tempering temperatures on microstructure and mechanical properties of 75Cr-Mo wear-resisting cast steel. The results reveal that quenching stress could be decreased effectively by using "air cooling + fog cooling" comparing with water quenching, thus avoiding initiation of micro crack. the microstructure of the quenched steel mainly comprises pearlite in addition to a little martensite and ferrite. M23C6 carbides, which have no crystal orientation with the matrix, disperses in the matrix. A hardness of 401 HBW and impact toughness of 35 J/cm2 were obtained for the steel when quenched after insulation for 2 hour at 880℃.