Interpass-Temperature-Dependent Dynamic Tensile Deformation Behavior of Wire Arc Additively Manufactured 316L Stainless Steel

This study investigates the influence of interpass temperature on the dynamic tensile deformation behavior of 316L stainless steel. Specimens were fabricated using cold metal transfer (CMT)-based wire arc additive manufacturing (WAAM) at interpass temperatures of room temperature (RT), 200 °C, and 400 °C, and tested at nominal strain rates of 100 s−1, 500 s−1, and 1000 s−1. Increasing interpass temperature promoted microstructural coarsening, reduced the continuity of the retained δ-ferrite network, and resulted in differences in the coincidence site lattice (CSL) Σ3 boundary fraction and the intensity of the ⟨001⟩ texture parallel to the build direction (BD), while decreasing the average hardness from 182 HV1 for RT to 173 HV1 and 161 HV1 for 200 °C and 400 °C, respectively. The RT condition exhibited the highest 0.2% proof stress, particularly at 100 s−1 and 500 s−1, whereas the tensile response tended to converge at 1000 s−1. Digital image correlation (DIC) revealed that the local strain distribution depended on both interpass temperature and strain rate, with more homogeneous centerline strain profiles at the highest strain rate. Scanning electron microscopy (SEM) fractography showed predominantly ductile failure by dimple rupture and microvoid coalescence. The screening results indicate that interpass temperature influences the dynamic tensile response of WAAM-fabricated 316L through changes in the as-deposited microstructure and the resulting plastic strain distribution, rather than through a change in the dominant fracture mode. These findings highlight interpass temperature as a relevant processing parameter for balancing interlayer waiting time, as-deposited microstructure, and dynamic mechanical response in WAAM-fabricated 316L.