Model of hardening elements of tools steel C80U

Abstract

Hardening is one of the manufacturing processes used for improving mechanical properties such as strength, hardness and wear resistances of the mechanical components for machine parts. This paper describes modelling of the processes of steel C80U hardening. The first priority was given to thermal phenomena, phase transformations in a solid state and mechanical phenomena. A numerical algorithm of thermal phenomena was based on the Finite Elements Methods in the Galerkin formula of the heat transfer equations. In the model of phase transformations, in simulations heating process, isothermal or continuous heating (CHT) was applied, whereas in the cooling process continuous cooling (CCT) of the steel. In the model of mechanical phenomena, apart from thermal, plastic and structural strain, transformations plasticity was also taken into account. The stress and strain fields are obtained using the solution of the Finite Elements Method of the equilibrium equation in rate form. The thermophysical constants occurring in constitutive relation depend on tem- perature and phase composite. In order to determine plastic strain, the Huber-Mises condi- tion with isotropic strengthening was applied, whereas for determination of transformation plasticity a modified Leblond model was used. In order to evaluate the quality and useful- ness of the presented models a numerical analysis of temperature field, phase fraction, stress and strain associated hardening process of a cone-shaped fang lathe made of tool steel was carried out.