Thermal fatigue analysis of H13 steel die adopted in pressure-die-casting process

Abstract

The thermal fatigue of die casting die steels causes reduction in tool life and seriously affects the surface conditions such as microstructure, hardness, surface finish and residual stresses. The improvement of die life by suitably modifying the die design assumes utmost importance for die designers. In this regard, a key issue is the size and location of cooling channels relative to the surface of the die, which affect the thermal stresses and fatigue life of dies. This paper focuses on thermal fatigue analysis of pressure-die-casting die steel H13 and analyses the effect of coolant channel location on temperature distribution and fatigue parameters such as life, damage, equivalent alternating stress and biaxiality using ANSYS Workbench 15.0 finite-element package. Increase in wall thickness (location of coolant channel from base) caused an increase in temperature and decrease in die life, which led to increase in volume porosity and hence crack initiation. The optimum coolant channel location from the base is obtained as 1 mm, which corresponds to minimum normal stress of 149.1 MPa, fatigue life of 4.1 × 105 cycles, fatigue damage of 2436.9 and equivalent alternating stress of 100.62 MPa.