According to the thermal-elasto-plastic theory

thermal stress model of cavity surface of die casting die during multiple die casting cycles was established

and the thermal stress to time curves of different depth points from cavity surface were analyzed.The results reveal that the point at the near distance from cavity surface exhibits a large thermal stress and thermal stress fluctuation.The die surface area within 3 mm is controlled mainly by low cycle thermal fatigue failure

while the area outside 5 mm is dominated by high cycle thermal fatigue failure

and the 3

5

mm region is between high cycle thermal fatigue failure and low cycle thermal fatigue failure.