Prediction of Martensite Start Temperature in Alloy Steels with Different Grain Sizes

A new equation to predict the martensite start (M (s)) temperature was proposed considering the effects of the chemical composition and grain size of austenite in alloy steels. The calculation results demonstrated that the addition of an alloying element decreased the M (s) temperature, and austenite with smaller grain sizes resulted in a remarkable reduction of the M (s) temperature. The variation of the M (s) temperature calculated by the proposed equation was in good agreement with experimental data of alloy steels with various grain sizes.