Investigation on elastic properties and unconventional plasticity of 316L stainless steel processed by selective laser melting technology

In general, traditionally manufactured steel alloys exhibit a typical elastic plastic deformation distinguished by linear and nonlinear stress–strain curves. However, an unconventional elastic–plastic behavior was observed from the 3D-printed 316L stainless steel specimens in this study, which showed no noticeable hardening in their elastic–near perfect plastic behavior. For comparison, similar tests were also performed on conventionally processed (hot rolled) 316L stainless steel samples. Microhardness indentation, resonant frequency, and tensile test have been performed on both types of samples and the results were compared with the ones available in the literature. Microstructural characteristics of the specimens produced by the two technologies were compared to explain the unconventional elastic–plastic behaviors of the 3D-printed specimens. Optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were performed for the analysis of microstructural characteristics of the specimens. High concentrations of dislocations along the grain boundaries were observed in the 3D-printed specimens that explains the increase of yield strength and exceptional plastic behavior of the material.