Microstructural heterogeneity and exceptional mechanical properties in a wire-arc additively manufactured stainless steel

Wire arc additive manufacturing (WAAM), thanks to the utilization of the electric arc as an energy source and metal wire as feedstock, has become one of the most cost-effective industrial-scale additive manufacturing techniques. The present study investigates the origin of the superior room temperature mechanical properties of AISI 316L stainless steel fabricated using WAAM. The yield strength (450 MPa ± 20 MPa) and uniform elongation (41.2% ± 2.5%) of the specimens extracted from the printed part are well higher than those reported in the case of conventionally manufactured counterparts. The findings from microstructural and elemental analyses reveal that the achieved non-equilibrium microstructure falls into the categories of dual-phase, periodic layered, and harmonic hetero-structured materials. In this respect, the contribution of hetero-deformation induced (HDI) strengthening in overall strength is determined to be 61.3 ± 2.2% through the loading-unloading reloading test.