Advancements in laser processes for additive Manufacturing: Techniques and future directions

Laser additive manufacturing has revolutionized industrial production, yet conventional focused Gaussian lasers have limitations such as high thermal gradients, high porosity, and grain roughness. This review systematically summarizes three kinds of advanced strategies to overcome these limitations, including the beam-shaping, laser oscillation, and multi-field assisted techniques. Beam shaping redistributes energy, reforms the melt pool, and stabilizes keyhole; oscillation periodically evolves the melt pool by adjusting the beam path; multi-field assisted technology introduces auxiliary physics fields to enhance melt-pool flow. Each technology elevates, to some extent, melt-pool stability, grain refinement and defect suppression. This comprehensive review of laser improvement strategies provides insights into current practices, challenges, and prospects.