Abstract: Selective laser melted Ti-6Al-4 V alloy usually exhibits low ductility due to the high cooling rate and complex thermal cycle during processing. Therefore, post-treatment is required to optimize the microstructure and mechanical properties. In the present study, electropulsing was applied to modify the microstructure by introducing dislocations and affecting the variant selection behavior. The difference in electric resistance between the prior-β grain boundary and the interior was significant and caused a large temperature difference during electropulsing heating. The large temperature difference would cause plastic deformation in the prior-β grains and bring in dislocations and residual compressive stress. Then the α variants simultaneously nucleated at the prior-β grain boundary and interior and competitively grew under stress resulting in a colony and basket-weave mixed microstructure. Due to the existence of basket-weave microstructure, which can hinder the motions of dislocations and microcracks, the electropulsing optimized alloy showed high strength-ductility synergy (yield strength, ∼925 MPa; elongation, ∼15%). However, heat treatment at a similar temperature (1293 K) caused a whole colony microstructure and showed a lower elongation (∼12%).

Key words: Selective laser melted Ti-6Al-4 V alloy, Electropulsing