Interface microstructure and evolution mechanism of wire arc additively manufactured H13 steel-copper hybrid components

The H13 steel-copper hybrid structure fabricated by additive manufacturing (AM) can achieve enhanced cooling of the system while ensuring certain high-temperature mechanical properties, showing broad application prospects in high-pressure die-casting molds. In this work, H13 steel was directly deposited onto a copper substrate by wire arc additive manufacturing, and the interface microstructure was studied in detail. The formation and evolution mechanism of the interface structure was revealed in combination with temperature field simulation. The Fe-Cu mixed liquid at the interface underwent two liquid phase separations, forming Fe-rich islands and Cu-rich islands, as well as dispersed Cu-rich particles. A small number of pores was formed due to the volume shrinkage of Cu during cooling. Microcracks were attributed to the effect of thermal stress and the high crack sensitivity caused by the distribution of Cu-rich particles at the original austenite grain boundaries. Due to the sharp changes in the element distribution at the H13-Cu interface and the continuous change in the temperature distribution, an extended molten pool with a temperature lower than the melting point of H13 and higher than the melting point of Cu was formed below the interface. The microhardness decreases gradually from the H13 side to the Cu side in a narrow range (similar to 0.5 mm) near the interface. The tensile sample of the hybrid component fractured on the Cu side away from the interface, and its tensile strength (221 +/- 2 MPa) reached the level of the Cu substrate, indicating that the interface formed a good bond.