Latent heat of martensitic transformation in a medium-carbon low-alloy steel

The latent heat of non-equilibrium martensitic transformation in AISI 4340 steel was obtained from experiments to measure the heat transfer coefficient and numerical calculations—using the inverse method based on the finite-difference method—of heat transfer and martensitic transformation kinetics. The average and maximum increases in surface temperature of a cylindrical specimen during oil quenching due to the temperature-dependent latent heat were 43 and 83 °C, respectively, indicating the importance of martensite latent heat for accurate heat treatment simulation.