Evaluation of spatter particles, metal vapour jets, and depressions considering influence of laser incident angle on melt pool behaviour

Abstract

The building of practical parts involves the application of metal-based powder bed fusion using a laser beam (PBF-LB/M), owing to its high-precision manufacturing. However, the quality of built parts obtained via the PBF-LB/M process varies with the building conditions, and a thorough understanding of the building mechanism has not been achieved owing to the complex and interrelated process parameters involved. The incident angle of the laser beam, which changes on the platform during the laser beam scan owing to the designed three-dimensional data, is among the principle parameters that affect the building aspects. In this study, the melt pool in the single-track formation during the PBF-LB/M process was visualised using a high-speed camera, and the influence of the laser incident angle on the ejection characteristics of spatter particles formed around the laser-irradiated area was investigated. Consequently, the spatter particles and metal vapour jets behaviour varied with the laser incident angle. There was a reduction in number of spatter particles owing to the origin of the incident direction being from behind the laser irradiation area. Additionally, the laser incident angle affected the melt pool morphology because of the depression in the melting. Furthermore, the burial depth of the pores varied with the laser incident angle, and was related to the depth of the depression during the melt pool formation.