Improved interfacial strength in bimetallic additive manufacturing of aluminum bronze/steel by controlling interface melting

A primary challenge of dissimilar materials additive manufacturing is inferior interfacial strength attributed to cracks, intermetallic compounds (IMCs), and residual stresses. To address these issues, a novel approach for controlling interface melting, bypass circumferential current metal inert gas (BCC-MIG) welding, was developed to fabricate aluminum bronze (AB) /steel bimetallic component for ship and marine applications. This technique involved directing the arc heat concentration onto central wire rather than base material. This approach achieved localized partial melting of steel, resulting in a defect-free metallurgical bonding interface. Microstructural characteristics and mechanical properties were systematically investigated with and without circumferential bypass current. In comparison to the non-bypass method, interface IMCs and cracks were eliminated, and the diffusion layer thickness was reduced to within 3.4 μm. The interfacial kernel average misorientation unveiled reduced interfacial residual stresses, attributable to lower peak temperature and reduced high-temperature dwell. Furthermore, the interfacial strength demonstrated a 13.3 % increase in yield strength (119.6 MPa), a substantial 39 % increase in ultimate tensile strength (558.7 MPa), and a remarkable 83.9 % increase in elongation (51.5 %), with fracture occurring within steel base material. This investigation provides valuable insights into controlling interfacial melting in additive manufacturing of different materials.