NUMERICAL MODELS AND THEIR VALIDITY IN THE PREDICTION OF HEAT CHECKING IN DIE CASTING

Heat checking is a major mode of failure of steel die surfaces in aluminum die casting. This cracking initiates due to the large thermal sh ock experienced by the die surface when it is rapidly quenched by the lubrican t spray and propagates due to thermal cycling during production due to t hermal cycling. Most of the previous studies have focused on the development of die steels and heat treatments for high fracture toughness using controll ed laboratory tests. Only a few examples exist of their application to the mechani c l behavior of dies. This paper examines the efficacy of numerical models in understanding the phenomenon and the prediction of cracking mode. It also p rovides insight into the validity of using the typical thermal fatigue theor ies in conjunction with the numerical models for life predictions in die castin g environment.