Heat-input-driven process window for wire arc additive manufacturing of Al–Mg/austenitic stainless steel bimetallic walls

Wire arc additive manufacturing of aluminium–austenitic stainless steel bimetallic walls is constrained by brittle interfacial intermetallic compounds and thermally driven stress/strain accumulation, which together promote interfacial cracking. Because both are governed by process heat-input, we developed a thermo-mechanical model to assess 12 heat-input levels (101–538 kJ/m) during gas metal arc welding deposition of Al5183 on AISI316L. The experimentally fabricated walls were investigated for interfacial microstructure and cracking. Insufficient heat-input led to incomplete wetting of the stainless steel substrate, whereas excessive heat-input intensified intermetallic growth, elevated thermal stresses and strains, and triggered interfacial cracking and delamination. A narrow processing window of 112–202 kJ/m was identified, corresponding to predominantly continuous metallurgical bonding and limited observed interfacial degradation under the investigated conditions.