Density Dependency of Tempered Martensite Hardness in Sintered Carbon Steel

The density dependence of tempered martensite hardness was studied and we have proposed a new equation to predict the hardness of tempered martensite sintered carbon steel.This was achieved by considering the density-dependent tempering value in the tempering parameter.The existence of porosity influenced both the decrease in tempered martensite hardness and the decrease in the activation energy for tempering, resulting in a lower tempering parameter.The variation of the hardness of tempered martensite predicted by the proposed equation was in good agreement with experimental data obtained under various tempering conditions and relative densities.[