Contour parameters, melt pool behavior, and surface roughness relationships across laser powder bed fusion platforms and metallic alloys
摘要
Components built using the laser powder bed fusion (PBF-LB) additive manufacturing (AM) process often have more complex surfaces than those produced by conventional manufacturing techniques. Features unique to the AM process are layering artifacts, adhered particles, and large stochastic valleys. Contour processing parameters are known to influence the resulting surface roughness; however, the generalized relationship between contour parameters, melt pool size and shape, and resulting surface roughness is not well understood. Typical PBF-LB metals, nickel superalloy 718 (In718) and AlSi10Mg, were built using a wide range of contour parameters (power and speed) and on multiple PBF-LB platforms with In718. Contour melt pool width and surface roughness were measured. Contour melt pool shape was characterized based on a novel approach that captures features such as balling instability and keyhole melting and considers both stable and unstable melt pool behaviors. In general, unstable contour melt pools had the highest values of both average roughness (Sa) and maximum valley depth (Sv). For In718, stable melt pools of increasing width led to reductions in both Sa and Sv. Similar trends were seen across platforms, but with different values to predict the process-melt pool-surface relationship. In AlSi10Mg, melt pool width was not correlated with surface roughness. Across alloys and platforms, specific melt pool widths would not be able to predict specific surface roughness values. This work provides a starting point for understanding how near surface melt pools influence the formation of surface roughness.