Three-dimensional simulation of quenching process of plaincarbon steel gears incorporating phase transformations

Abstract

In the present work, a numerical model was developed for the simulationof the quenching process of plain carbon steel gears in water and oil usingfinite element method. For diffusional transformations, the Johnson–Mehl–Avramiequation was coupled with the additivity rule, while for non-diffusional transformation,the empirical model of Koistinen–Marburger was employed. In addition,the model of Maynier et al. was used to compute the hardnessdistribution throughout the parts. To evaluate the cooling power of quenchingmedia, the heat transfer coefficients of quenching media were calculated bysolving an inverse problem using a stainless steel probe. In addition, a novelapproach was applied for computing the actual phase fractions in the multiphasesteel. The effects of the latent heat releases during phase transformationsalong with the effect of temperature and phase fractions on the variationof thermophysical properties were considered. Experimental tests includingcooling curve analysis, metallographic investigations and hardness measurementswere performed to evaluate the validity of the model. The comparisons indicatedthat the simulation results were consistent with the experimental results.The multiphase transformation model presented here is capable to predict thedistribution of temperature, microstructures and hardness during continuouscooling of steel.