Estimation of Hardness During Heat Treatment of Steels

Abstract

A hardness model employing the end quench Jominy method is developed for steels C25, EN8, EN19, EN31 and EN24. The time-temperature data are obtained from four thermocouples mounted at critical places of a specimen. The heat flux during the quenching is determined from the cooling curve obtained with the help of the thermocouple closest to the end of the specimen (quenching place). The two-dimensional axisymmetric equation of heat conduction is solved and used jointly with the models of decomposition of austenite to obtain the distribution of microstructure at the places used to plot the cooling curves. The computed distribution of microstructure and the chemical compositions of the steels are used to estimate the hardness. The computed hardness values agree well with those determined experimentally over the length of the specimen.