Benchmarking of Print Properties and Microstructures of 316L Stainless Steel Laser Powder Bed Fusion Prints

Laser powder bed fusion (L-PBF) is an established technology in metal additive manufacturing. This manufacturing process yields unique as-built material properties that influence mechanical performance. High porosity and residual stresses can lead to part failure, and intricate grain structures yield anisotropic strength. Physical and mechanical properties vary complexly for different machine parameters. As such, an accessible methodology for multi-property characterization is required for comparing L-PBF prints. This work presents results for density, residual stress-induced distortion, and microstructural inspections on designed test artifacts for the benchmarking of 3D metal printers. Results from printing artifacts in stainless steel 316L on two separate L-PBF printer models with default parameters show highly dense parts for both printers, with relative densities above 99.5%. Characterization of distortion through cantilevered deflection specimens indicates similar resulting thermal stresses developed in both build processes. Additionally, properties of test artifacts printed after adjusting default machine parameters for equal energy density are characterized. A resulting unconventional microstructure with deep and narrow melt pools, high relative density (> 99.9%) despite no overlap, and increased strength in the build direction is discussed. Two energy density equations, one with an added dimensionless parameter, are tested and analyzed for their limitations in setting process parameters.