Design of overlay coated region with hardfacing, transition and damage diminution layers for the reduction of damages of hot forging tools

Abstract

Hot forging dies are damaged by the mixed failure modes including wear, thermal cracks, impact cracks, corrosion cracks, etc.. In order to extend the service life of the hot forging die, the diminution technology of the mixed failure modes should be developed. The aim of this paper is to design an overlay coated region consisting of a Hardfacing layer (HL), a Transition layer (TL) and a Damage diminution layer (DDL) to reduce damage of hot forging tools. The HL and the DDL are contrived to improve the wear resistance and the ductility of the overlay coated region, respectively. The TL is adopted to prevent thermal fatigue induced by the difference in the thermal expansion coefficients between successive layers. In order to estimate design alternatives of the overlay coated region, the effects of the thickness and the assignment of the DDL on stress-strain distributions in the overlay coated region are investigated via Finite element analyses (FEAs). The influence of the assignment of the DDL on thermal behaviors of the overlay coated region is investigated through thermal fatigue experiments. From the results of the FEAs and the thermal fatigue experiments, an appropriate design of the overlay coated region is determined.