The Model and Numerical Analysis of Hardening Phenomena for Hot-work Tool Steel

In the paper the complex model of hardening of the hot-work tool steel is presented. Model of estimation of phase fractions and their kinetics is based on the continuous cooling diagram (CCT). Phase fractions which occur during the continuous heating and cooling (austenite, pearlite or bainite) are described by Johnson-Mehl-Avrami-Kolmogorov (JMAK) formula. To determine of the formed martensite the modified Koistinen-Marburger (KM) equation is used. The stresses and strains are calculated by the solution of equilibrium equations in the rate form. Model takes into account the thermal, structural, plastic strains and transformation plasticity. The thermophysical properties occurring in the constitutive relations are dependent on phase compositions and temperature. To calculate the plastic strains the Huber-Mises plasticity condition with isotopic hardening is used. Whereas to determine transformations induced plasticity the Leblond model is applied. The numerical analysis of phase compositions and residual stresses in the hot-work steel element is considered.