Comparison of the Influence of Cooling Medium on Stress State during Superficial Hardening for the Hot-Work Tool Steel

The paper presents a complex analysis of superficial hardening for hot-work tool steel to optimize the residual stress state.It was assumed that the main factor influencing the quality of the hardened element is the use of an appropriate cooling medium.Two groups of cooling media were consideredgases and solids.The group of gases is represented by air and solids by fluidised bed.The numerical algorithm of thermal phenomena is based on the finite element method solution of the non-stationary heat transfer equation.The model of estimating phase fractions and their kinetics is based on continuous heating and cooling diagrams.The stresses and strains were determined from the solution of thermoelasto-plasticity problem in the rate form.The numerical analyses of phase composition and hardening stresses in surface hardened elements made of hot-work tool steel were performed.