Interfacial Microstructure and Mechanical Performance of Stainless Steel-Low Alloy Steel Bimetallic Structures...

Bimetallic structures (BMSs) are being used more frequently in industries like automotive, aerospace, and shipbuilding because they combine different material properties in a single component. Traditional methods like welding and brazing have their limits, but additive manufacturing (AM) offers a more flexible and cost-effective way to create complex multimaterial parts. This study focuses on the microstructure and mechanical properties of BMSs made by depositing stainless steel (SS) on high-strength low-alloy (LA) steel using the Wire Arc Additive Manufacturing (WAAM) process with Surface Tension Transfer (STT). The results show that defect-free BMSs can be successfully fabricated, improving design possibilities. Microstructural analysis revealed a clear Ferrite-Austenite (FA) boundary at the SS-LA interface. Key findings include an 81.81% increase in hardness at the interface relative to the LA steel side, along with an interface tensile strength of 621 ± 7 MPa and elongation of 19.28% ± 1.76%. Electron backscatter diffraction (EBSD) showed fine, randomly oriented grains in the SS region and elongated, directionally aligned grains in the LA region, with no dominant texture, indicating near-isotropic behavior. The presence of both low-angle and high-angle grain boundaries confirmed dynamic recrystallization during deposition. Fracture analysis showed strong mechanical bonding, with failure mainly occurring on the LA side. This demonstrates that WAAM with STT is a viable method for creating reliable, high-performance multimaterial components.