Direct metal laser sintering (DMLS) is an established technology in metal additive manufacturing. This complex manufacturing process yields unique as-built material properties that influence mechanical performance and vary with different machine parameters. Part porosity and residual stresses, which lead to part failures, and grain structure, as it relates to mechanical properties and anisotropy of DMLS parts, require investigation for different print settings. This work presents results for density, residual stress, and microstructural inspections on designed test artifacts for the benchmarking of 3D metal printers. Results from printing artifacts on two separate DMLS printer models with default parameters show highly dense parts for both printers, with relative densities above 99.5%. Characterization of residual stress through cantilevered deflection specimens indicates similar resulting thermal stresses developed in both build processes, with deflection averages of 32.48% and 28.09% for the respective machines. Additionally, properties of the test artifact printed after adjusting default machine parameters for equal energy density are characterized.

Gas nitriding is proving to be a viable low temperature case hardening process for stainless steels used in numerous applications. In this study, a comparison between austenitic (grade 304) and martensitic (grade 401) stainless steels shows how pre-oxidation temperature affects the thickness and porosity of the compound layer produced as well as hardness and nitriding diffusion depth. The results indicate that austenitic stainless steel would be the best choice for a part requiring wear resistance and strength, and that a standard rolled martensitic stainless steel would suffice if only a wear resistant surface is needed.