Abstract
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.
