Understanding Spatter and Its Spatial Variations in Laser Powder Bed Fusion of Ti6Al4V

Additive manufacturing (AM) by laser powder bed fusion (L-PBF) is rapidly developing as a principal method for the manufacture of metal parts. However, widespread adoption of the technology, especially for safety-critical applications, is impeded by complications to achieving the desired component quality and reliability. Spatter occurs due to interactions between the laser and the melt pool and involves the ejection of material from within or about its vicinity. Recognized as a process signature in L-PBF, spatter is considered detrimental to build quality. However, relationships between spatter kinetics and part defects have remained largely underexplored. In this investigation, spatter is evaluated via in situ optical tomography (OT) imaging acquired during builds performed with Ti6Al4V powder. Results showed that the volume of spatter content is greater at particular scan angles as well as specific locations in the build chamber. Furthermore, the spatter dynamics behave differently upwind and downwind of printed regions and indicate that local variations in gas flow can be inferred from spatter signatures. As spatter is known to directly cause defects in parts produced by L-PBF, regions with increased spatter potentially signal reduced metal quality. Variations in the spatter content are identified and regions of the build at greater risk for defects are highlighted.