Study of the Effect of Surface-Roughness of Dies and Tooling for HPDC on Soldering

Die-casting processes are commonly employed in the automotive area to cast aluminum alloys. These processes involve the use of steel dies, typically realized in AISI H11 or H13, with or without a coated surface. Mechanical and chemical stresses and thermal cycles act producing stresses, plastic deformation, corrosion and metallization on the mold surfaces. Particularly, the interaction between the die and the molten aluminum causes the nucleation of intermetallic compounds at the interface. In this work the interaction between the hot work steel AISI H13 and the aluminum alloy EN-AB 46000 were evaluated in terms of adhesion strength for different roughness of the die surface. Two of the tested roughness were finally applied on the surface of die inserts; the use of injection pressure in a high pressure die casting (HPDC) machine, led to observe the possible variations in terms of soldering severity on the surface of the die in real operating conditions. The comparison between casting tests carried out in laboratory conditions (aluminum alloy casted on the steel surface) and in real-work conditions (aluminum alloy injected with a certain pressure on the steel surface) allowed to evaluate the effect of surface-roughness on soldering mechanisms.