Solidification behavior and grain morphology of laser additive manufacturing titanium alloys

Abstract The prior β grain structure is recognized to be an important factor governing the mechanical properties of laser additive manufacturing (LAM) titanium alloys (ti-alloys) components. Five kinds of ti-alloys plates were fabricated by LAM process aiming to investigate the solidification behavior and grain morphology. Full columnar grains, full equiaxed grains and a special mixed grains structure were observed in LAM TC4, TB6 and TC11 plates, respectively, indicating that the formation tendency and volume fraction of equiaxed grains in LAM ti-alloys plates increase gradually with the increasing alloying content. It was proposed the formation of equiaxed grains is a multifactor functioning result of the constitutional supercooling and the remaining powders in the local melting pool.