Microstructure and tensile properties of 3%Cr–0·5%Mo high carbon PM sintered steels

Abstract

Tensile properties of 3%Cr–0·5%Mo sintered steels vary greatly depending on the sintering temperature, compaction method and cooling rate. Given the high cooling rate and carbon content, the microstructure is either fully martensitic or bainitic–martensitic, with different amounts of bainite. Microhardnesss of the sintered samples is very high, ranging between 650 HV0·05 and 950 HV0·05, therefore, materials have a tendency to be brittle and their properties improve after a low temperature tempering. The best mechanical properties were obtained on the bainitic–martensitic materials sintered at high temperature.

The present work demonstrates the possibility of obtaining excellent tensile properties using a 3%Cr–0·5%Mo prealloyed powder to form a dual phase microstructure, comprising of martensite and lower bainite in equal amounts.

Keywords:

• TENSILE PROPERTIES
• SINTERED STEELS
• HIGH CARBON CONTENT