Selective laser melting of 316L stainless steel/ TiC metal matrix composite

Abstract

Selective Laser Melting (SLM) is one of the most popular Additive Manufacturing (AM) techniques as it enables users to create high complexity and density parts with good mechanical properties, especially in the modern industry. The process of SLM produces layers and layers of 2D profiles from a 3D CAD software. These profiles are laser melted individually onto a substrate that has a metal powder feedstock spreading over it. The layers will ultimately be built upon one another and a part is formed. Prior to printing, the metal powder mixture was studied as the irregularities and defects of powder shapes would affect the density of the printed sample. Furthermore, the presence of porosity would affect the mechanical properties of the final build SLM product. To analyse the microscopic properties of the SLM printed samples, pure 316L powder and TiC particles in 2 different parameters, 1% TiC and 3% TiC by weight, were mixed using ball milling process at low energy. After the SLM process, the sample parts were cut, mounted onto a resin, grinded, polished and etched before being able to view their microstructure under an optical microscope. This report analyses pure 316L stainless steel by SLM, 316L-1TiC and 316L-3TiC Metal Matrix Composite (MMC) by SLM. Through an optical microscope, the grain boundaries, porosities, melt pools, columnar grain microstructure were observed. Microhardness testing was analysed to determine the mechanical properties of the build product and is found that the 316L-1TiC and 316L-3TiC has a 15.2% and 30.9% increase in microhardness value when compared to 316L by SLM