The effect of primary processing parameters on surface roughness in laser powder bed additive manufacturing

Metal additive manufacturing (AM) is a method to create complex components in a layer-by-layer process. Laser powder bed fusion (LPBF) provides the ability to fabricate complex designs. Components with internal geometries have surfaces that are difficult to improve through post-processing and have been shown to be detrimental to mechanical performance. This work investigates the relationship between primary processing parameters, and surface roughness of nickel-based superalloy 718 fabricated on a LPBF AM machine. The surface roughness of components built using varied contour processing parameters was characterized using both nondestructive and destructive measurement techniques. Statistical correlations are presented between contour processing parameters and surface roughness height metrics along with general trends in the relationships. Results show that the destructive measurements are required to expose notch-like features that are obstructed by powder particles attached to the surface. However, nondestructive methods more easily provide a statistically significant sample size. Understanding the surface roughness can be used for further process optimization and to inform the qualification strategy for AM components.