Thermal stresses in aluminium alloy die casting dies

The aim of this research is to analyze the influence of Aluminium Alloy die casting parameters, die material, and die geometry on in-service tool life. An innovative immersion testing apparatus is developed, at which Aluminium Alloy die casting is simulated. It enables controlled thermal fatigue cycling. Special specimens with different edge geometry and specimens with maraging steel welds deposited by Gas Tungsten Arc (GTA) welding are prepared. They are subjected to cyclic heating in bath of molten Aluminium Alloy 226 and cooling in bath of water-based lubricant. The specimens are continuously internally cooled with cold water. The microstructure, hardness profile, and the surface cracks developed are periodically analyzed after completion of a particular number of cycles. Temperature transients at different locations of the specimens are measured and used in calibration of finite element model (FEM). The computation of transient stresses is performed by developed FEM. The influence of immersion test parameters, material, specimen edge geometry, and thickness of maraging steel surfacing welds on thermal stresses is studied. To improve thermal fatigue testing efficiency, a specimen of particular geometry and immersion test parameters are developed based on finite element analysis. The results showed significant differences in produced thermal stresses for analyzed materials, test parameters, and edge geometries. Maraging steel is found to be superior material for die casting dies, due to generation of lower stresses.