Ultrafine microstructure development in laser polishing of selective laser melted Ti alloy

BRIEFS. By a supervised machine learning and laser polishing method, ultrafine α′ martensite lath and secondary mechanical twinning has been characterized on polished layer, and the micro-hardness and deformation resistance on SLM Ti-6Al-4V alloy were increased. • Microstructure development of laser-polished alloy is crucial for surface intensity and its perform. • A laser polishing optimization system for SLM Ti-6Al-4V alloy is developed based on a supervised machine learning. • Ultrafine sub-microstructure of laser surface polishing for SLM Ti-6Al-4V alloy is demonstrated. • Laser-polished layer consists of ultrafine α′ martensite laths with average size of 0.6 μm. • TEM investigation examines the interactions of SFs-dislocations and nanoscale intergranular β particles.