Experimental investigation into selective laser melting of austenitic and martensitic stainless steel powder mixtures

Abstract

Selective laser melting (SLM) is a novel additive layer manufacturing method that has been used to directly consolidate a wide range of metallic powders to form net-shape metallic parts for various engineering applications. It is capable of processing steel powders in a range of grades and also allowing the creation of custom alloys by consolidating the mixed powders of two or more grades. This study investigates the effects of varying the ratio of austenitic and martensitic powder mixtures on the laser consolidation of steel parts. Specimens were fabricated by SLM processing from 316L austenitic and 17-4PH martensitic stainless steel powder mixtures with varying composition ratios. Mechanical and magnetic properties of the specimens were assessed by micro-hardness testing and comparison of ‘magnetic adherence’ forces. The composition ratios of the mixed powders have been found to influence the laser consolidation mechanisms and the resulting microstructures in the specimens. The microstructures play an important role in altering the micro-hardness and the magnetic properties of the specimens and determining a definite relationship between these two properties. The results of this study prove that a new stainless steel grade can be produced via the SLM process to have tailored mechanical and magnetic properties.