Uncertainties Induced by Processing Parameter Variation in Selective Laser Melting of Ti6Al4V Revealed by In-Situ X-ray Imaging

Abstract

Selective laser melting (SLM) additive manufacturing (AM) exhibits uncertainties, where variations in build quality are present despite utilizing the same optimized processing parameters. In this work, we identify the sources of uncertainty in SLM process by in-situ characterization of SLM dynamics induced by small variations in processing parameters. We show that variations in the laser beam size, laser power, laser scan speed, and powder layer thickness result in significant variations in the depression zone, melt pool, and spatter behavior. On average, a small deviation of only ~5% from the optimized/reference laser processing parameter resulted in a ~10% or greater change in the depression zone and melt pool geometries. For spatter dynamics, small variation (10 μm, 11%) of the laser beam size could lead to over 40% change in the overall volume of the spatter generated. The responses of the SLM dynamics to small variations of processing parameters revealed in this work are useful for understanding the process uncertainties in the SLM process.

Crystallographic texture configured by laser powder bed fusion additive manufacturing process: a review and its potential application to adjust mechanical properties of metallic products

“…1. the great advances, innovations, and diversity of conditions, results, and applications that have been presented recently [9,10,20,28] and 2. the intrinsic procedural complexity, associated with the large number of parameters linked to AM [11,14,32,53].…”

“…Finally, Reijonen et al [43], as well as Young et al [53], point out that AM by LPBF exhibits other uncertainties, where variations in results are present despite using the same optimized processing parameters. Some of these conditions are the brand and model of the LPBF equipment, chamber size, shielding gas type, flow rate and direction, type of laser return on island boundaries (curved or stopped), size and geometry of the part itself, number of parts being built inside the chamber.…”

“…This practice produces different energy inputs to the molten pool, thus altering the microstructure and texture results, as presented by Pham et al [44] not necessarily improving it. The angle of incidence of the laser beam can change energy input and as pointed out by Young et al [53]. In this case, more robust conditions are needed to guarantee the stability of oriented grain growth even with variations on incident laser beam angle along all building parts inside LPBF chamber.…”

A Review of Spatter in Laser Powder Bed Fusion Additive Manufacturing: In Situ Detection, Generation, Effects, and Countermeasures

“…Laser diameter: The laser spot size during L-PBF can significantly affect the melt dynamics and droplet spatter generation [117]. There are two reasons for the variation of the spot size: passive variation and active variation.…”