Impact of post treatment processes on the performance of 316L stainless steel parts manufactured through metal material extrusion additive manufacturing

Material Extrusion for metal parts (Metal MEX) is a multi-step Additive Manufacturing technology based on the layer-by-layer extrusion of a composite material, which consists of metallic powder and polymeric binders. Debinding and sintering are subsequently required to remove the polymers and densify the parts, thus obtaining the desired metal material properties. Once sintered, the internal and external characteristics of the metal parts are often affected by defects generated during this process chain. In this context, the adoption of post-treatment processes, such as heat treatments and surface mechanical treatments, can provide potential benefits for the performance of the as-sintered parts. In this study, a highly filled filament with ≈ 90 wt% of 316 L stainless steel powder was used to realize the tested samples. Heat treatment at 400 °C for 4 h and a two-step surface mechanical treatment (air-compressed sand-blasting and shot-blasting) were considered as two distinct post-treatment approaches. The performance of the parts and their anisotropic behavior, according to the selected post treatment processes, were investigated and discussed.