Characterization of the microstructures and mechanical properties of 25CrMo48V martensitic steel tempered at different times

The microstructures of 25CrMo48V martensitic steel quenched (Q) at 900 °C and tempered (T) at 650 °C for 5–105 min were characterized by transmission electron microscope (TEM). The tensile and impact properties were evaluated from the Q–T treated samples. The results indicate that the precipitate size is increased with the prolonged soaking time and the dependence of volume fraction of precipitated particles on the tempering time follows the classical Johnson–Mehl–Avrami (JMA) model. The refinement precipitated particle could induce the enhancement of yield strength. The dependence of the yield strength of 25CrMo48V martensitic steel tempered at 650 °C for different times on the lath width and the precipitated particle size can be described as σy=645+145w−1+1.27×10−17Dp−13.