Geometric and mechanical properties of wire laser additive manufactured S308L stainless steel

Abstract This study comprehensively investigates the geometric properties, mechanical properties, and microstructural characterisation of wire laser additive manufacturing (WLAM) S308L stainless steel under different loading directions, where the effects of heat treatment are also studied. The geometric characteristics obtained from 3D scanning models were used to evaluate the geometric undulation of the printed specimens. The mechanical properties, including tensile behaviour and impact toughness, were studied through physical tests. The results indicate that anisotropic behaviour is pronounced in this material. For the non-heat-treated specimens, the average values of the Young’s modulus at 0°, 45°, and 90° are 202.78, 177.36, and 181.86 GPa, respectively. The corresponding fracture strains are 55.04%, 59.91%, and 42.12%, respectively. The influence of heat treatment is found to depend on both the extraction angle and the specific mechanical parameter. For example, for the 90° specimens, heat treatment reduced the Young’s modulus by 22% but increased the fracture strain by 40%. The impact toughness is also affected by both the extraction angle and the heat treatment condition. Electron backscatter diffraction was conducted to reveal the origins of material anisotropy, which is related to directional crystallographic textures caused by the thermal gradient. Based on the test results, the Ramberg-Osgood model is utilised to describe the full range stress-strain curves of the WLAM S308L stainless steel. The material anisotropy behaviour is characterised using a plane orthotropic stress model and Hill’s yield criterion for elastic and inelastic stages, respectively.