The enhancement of mechanical properties via post-heat treatments of AISI 630 parts printed with material extrusion

Metal material extrusion is a novel additive technique gaining relevance due to its low cost and ease of use compared to traditional metal additive technologies. However, an overall feasibility, including structural and mechanical properties, should be assessed to implement this newly technology within the manufacturing sectors. The aim of the present paper is to conduct a comprehensive characterization on material extrusion (ME) printed AISI 630 stainless steel. Metal samples were produced by means of a commercial ME machine with a polymeric flament loaded with AISI 630 stainless steel powder. A structural analysis, based on a Taguchi DoE and an analysis of variance, provided the best process parameters combination, ensuring the highest apparent density. A mechanical analysis was performed to evaluate the efects of traditional heat treatments on sintered samples. H900 specimens exhibited the highest yield and ultimate tensile strength (1028±80 MPa and 1124±49 MPa, respectively). Over-aged treatment (H1150) led to an improvement of the ductile behavior of the specimens, compared to the sintered ones. SEM observation revealed a common fracture behavior, which occurs to the interface between two adjacent layers, regardless of the conditions of the samples. According to the obtained results, metal ME proved to be a robust and sustainable technique to produce metal components requiring good mechanical properties. Solution and aging treatments enhanced the mechanical characteristics of AISI 630 ME samples reducing the diferences with respect to the corresponding values of tempered monolithic ones in terms of strength, ductility, and hardness.