Pulse Shaping Modulation on Defects Control in metal additive manufacturing via Powder Bed Fusion

The Powder Bed Fusion (PBF) additive manufacturing method is widely used but faces challenges such as porosity and fusion defects. These issues stem from the transient temperature field generated during laser-matter interaction. In this study, we explore the use of pulsed lasers in PBF and investigate how shaping the laser pulse in the time domain can mitigate defects. By designing a smooth heating rate to sinter powder grains followed by a sharper heating rate to generate a fully molten region while reducing ablation, we aim to control the transient temperature field. We employ various techniques including X-ray microtomography, molecular dynamics, X-ray diffraction, Electron Backscatter Diffraction, and finite element simulations to analyze build quality. Our findings demonstrate that shaping the laser pulse influences porosity, lack of fusion, residual stresses, and microstructure, opening avenues for optimizing PBF processes.