Engineered metallic interlayers for controlled part-substrate detachment in wire arc additive manufacturing

Abstract Substrate removal in Wire Arc Additive Manufacturing is a complex, laborious process, especially for intricate geometries. This study investigates a novel release strategy using engineered metallic interlayers to induce controlled fracture at the part-substrate interface. To validate this, ER70S-6 steel walls were deposited onto S355 substrates utilising copper and aluminium interlayers. Deposition speed was varied to control interlayer dilution and assess its impact on microstructural and mechanical responses. Bonding integrity and strength were evaluated via SEM–EDS, computed tomography, microhardness mapping, and monotonic/cyclic tensile testing. Results demonstrate that engineered interlayers significantly reduce part-substrate interface strength, enabling detachment with minimal force. Specifically, copper promoted extensive interfacial solidification cracking, allowing separation at the lowest applied loads. Conversely, aluminium caused localised interfacial thinning, enabling controlled detachment through geometric weakening rather than extensive internal damage. Furthermore, microhardness profiles revealed localised embrittlement, contributing to the overall weakening mechanism. In this way, the current research validates the use of engineered metallic interlayers as a cost-effective, non-destructive method for substrate removal, offering a scalable solution to automate post-processing in industrial WAAM workflows.