Characterization of 304L stainless steel by means of minimum input energy on the selective laser melting platform

Developing parameter sets for new materials on the Selective Laser Melting (SLM) platform has traditionally been done through the use of single line processing windows and a basic design of experiments (DOE) which would include varying machine parameters to maximize density. This study expands the traditional method by determining the main effects statistically for density, allowing for a more in depth analysis wherein the experimental results are statistically correlated to the variable machine parameters used. With this analysis, parameter optimization with respect to achieving near full density, while also considering build rates, can be performed. New parameters for 304L stainless steel were developed using this method on a Renishaw AM250. Single line processing windows were used to determine bounds on machine parameters. Utilizing this information, a DOE was implemented in which density samples were fabricated and the statistical main effects on density were derived. Several methods for density determination were also investigated as part of this study. In order to quantify machine parameters, a novel energy density term was formulated. Optimal parameter sets were found and energy density was reduced to increase build rate. Sensitivity of mechanical properties to the reduction was shown to be minimal over the range tested. Finally, the effect of decreased energy density on microstructure, part density, mechanical properties, and orientation sensitivity were then measured --Abstract, page iii