The influences of chromium addition and quenching treatment on the mechanical properties and fracture behaviors of diffusion-alloyed powder metal steels

The addition of Cr and quenching treatment have been found to increase the tensile strength of diffusion-alloyed powder metal steels. However, the influences of these two methods on the impact toughness and fracture behaviors are still unclear. The objective of this study was to clarify the effects of 0.5 wt% Cr and quenching treatment on the mechanical properties and fracture behaviors of diffusion-alloyed powder metal steels under tensile and impact loadings. sults showed that the addition of Cr helps strengthen and homogenize the sintered microstructure. The tensile strength is thus improved by 38%, while the impact energy is lowered by 15%. Quenching treatment improves the tensile strength by 46% because martensite forms at the expense of low-strength pearlite. However, the loss of impact energy due to quenching treatment is as high as 32%. These findings demonstrate that the addition of Cr is a feasible method to strengthen diffusion-alloyed PM steels without obviously sacrificing toughness.