AISI 316L base material and welded specimens produced by DMLS: global and local experimental analysis under tensile loadings

The mechanical behaviour of AISI 316L stainless steel manufactured via Direct Metal Laser Sintering (DMLS) was evaluated in both non-welded and welded conditions. The investigation integrated tensile testing, Vickers microhardness mapping, and thermographic monitoring with detailed post-fracture observations. To bridge the gap between global tensile response and localized performance, local true stress-true strain curves were reconstructed from hardness data using the Lopez-Fatemi and Kamaya analytical approaches. This allowed for a local assessment of the base material (BM), heat-affected zone (HAZ), and weld metal (WM). Results indicate that welding significantly degrades the overall mechanical performance and introduces pronounced local gradients, characterized by a progressive decrease in hardness and strength from the BM toward the WM. These findings, further supported by thermographic and fracture analyses of distinct deformation and failure mechanisms, provide a critical experimental foundation for the development of accurate non-linear finite element models.