This study presents the fabrication and characterization of a nickel–aluminium bronze (NAB)–high-strength low-alloy (HSLA) steel bimetallic structure produced using wire arc additive manufacturing (WAAM). Tailored gas metal arc welding (GMAW) parameters, incorporating a voltage-controlled pulsed arc, controlled torch oscillation, and a bidirectional deposition strategy, are employed to achieve robust metallurgical bonding at the dissimilar-metal interface. Comprehensive characterization using optical and electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, hardness mapping, and tensile testing is conducted to evaluate interfacial microstructure, phase evolution, and mechanical integrity. A defect-free, compositionally graded interface is formed through controlled interfacial remelting and elemental interdiffusion between NAB and HSLA steel, avoiding an abrupt transition. Distinct Cu-rich and Fe-rich dilution zones form, with the coexistence of α-Cu, α-Fe, and κ phases confirmed at the interface, while elemental mapping reveals continuous Cu–Fe diffusion, contributing to a smooth hardness transition. The bimetallic structure retains tensile strength comparable to monolithic materials and predominantly ductile fracture behavior, confirming effective load transfer across the interface. The results establish GMAW-WAAM as a reliable route for producing NAB–HSLA bimetallics with graded, diffusion-controlled interfaces and effective load transfer, enabling structurally sound components for demanding marine and load-bearing applications. These findings highlight the effectiveness of controlled GMAW-WAAM processing in achieving robust interfacial bonding and property gradients in NAB–HSLA steel bimetallics, supporting their integration into advanced multi-material structures. • NAB–HSLA steel bimetallics fabricated using process-controlled GMAW-WAAM • Defect-free, compositionally graded NAB–HSLA interface achieved • Cu–Fe interdiffusion forms smooth hardness and property transitions • α-Cu, α-Fe, and κ phases coexist at the dissimilar-metal interface • Bimetallics show ductile fracture and effective interfacial load transfer
Kanishka et al. (Wed,) studied this question.