Suppression of powder spattering in powder bed fusion with core-ring laser beam

Powder spattering and denudation are critical issues in laser powder bed fusion (LPBF) processes, both of which contribute to the formation of defects in the fabricated parts. Recent experimental studies indicate that non-Gaussian laser beam profiles can significantly affect powder spattering and denudation behavior. However, none of these studies have explicitly highlighted the direct impact of the ring laser on potential spattering particles. To accomplish this, the study employs a combination of experimental and numerical methods to investigate a core-ring beam configuration that includes a Gaussian core beam and an auxiliary ring beam. Various core-to-ring power ratios and total laser powers are examined at a scanning speed of 0.4 m/s, using Ti-6Al-4V powder and substrate in an Argon atmosphere. Experimental observations of powder behavior are conducted via high-speed imaging, while a three-dimensional multiphysics model simulates vapor plume dynamics, vapor-powder interaction, and powder motion. Among those configurations, the case with 70 W applied to both the core and ring beams shows the most significant spattering suppression, resulting in a 42% reduction in spattered particles compared to the case with the same core power without a ring laser. The primary mechanism of spattering suppression, whereby ring laser pre-heating enlarges the molten pool size, merging particles before they are ejected by the high-speed vapor plume, is elucidated through detailed simulation analyses. This finding highlights the potential of auxiliary laser beam modulation as an effective strategy for reducing powder spattering and thereby improving part quality in LPBF.