Beam shaping is considered a technology capable of dramatically improving quality and robustness of Laser Metal Fusion (LMF) processes. However, systematic investigations of its effects on melt-pool dynamics, temperature field and microstructure are still required. In this work, we propose an integrated approach combining a Computational Fluid Dynamics (CFD) model, in-situ temperature measurements and metallographic analysis to explore programmable ring beam profiles, ranging from Gaussian-dominant to ring-dominant configurations. This method, initially proposed on Ti-6Al-4V bead-on-plate tracks, validates melt-pool temperatures measured in-process by a dual-wavelength pyrometer against CFD predictions, which are in turn validated with metallographic cross-sections. Ring modes lowered peak temperature by up to 35 %, transforming deep-narrow pools (aspect ratio ≈0.9) into shallow-wide ones (≈0.4). This suppressed humping at line energies ≥ 0.28 J mm−1, whereas lower energies produced only superficial melting. Simulations matched pyrometer data within 5 % whenever pool width equalled the pyrometers’ sensing spot; all tracks solidified into ultrafine α with retained β, independent of beam mode. Therefore, the combination of in-situ, ex-situ and CFD tools offers a practical workflow for assisting data-driven process optimization and can be easily extended to other LMF processes, with its potential implementation in industrial Laser Powder Bed Fusion.
A comprehensive framework to study the influence of beam shaping in laser metal fusion processes
Ancona, Antonio
2025-01-01
Abstract
Beam shaping is considered a technology capable of dramatically improving quality and robustness of Laser Metal Fusion (LMF) processes. However, systematic investigations of its effects on melt-pool dynamics, temperature field and microstructure are still required. In this work, we propose an integrated approach combining a Computational Fluid Dynamics (CFD) model, in-situ temperature measurements and metallographic analysis to explore programmable ring beam profiles, ranging from Gaussian-dominant to ring-dominant configurations. This method, initially proposed on Ti-6Al-4V bead-on-plate tracks, validates melt-pool temperatures measured in-process by a dual-wavelength pyrometer against CFD predictions, which are in turn validated with metallographic cross-sections. Ring modes lowered peak temperature by up to 35 %, transforming deep-narrow pools (aspect ratio ≈0.9) into shallow-wide ones (≈0.4). This suppressed humping at line energies ≥ 0.28 J mm−1, whereas lower energies produced only superficial melting. Simulations matched pyrometer data within 5 % whenever pool width equalled the pyrometers’ sensing spot; all tracks solidified into ultrafine α with retained β, independent of beam mode. Therefore, the combination of in-situ, ex-situ and CFD tools offers a practical workflow for assisting data-driven process optimization and can be easily extended to other LMF processes, with its potential implementation in industrial Laser Powder Bed Fusion.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
