Effect of Nb on Microstructure and Properties of Laser Additive Manufacturing TC4 in Deposited State

TC4 and TC4+Nb deposited samples were prepared by laser coaxial powder feeding additive manufacturing, and the effects of Nb on the microstructure, phase composition and mechanical properties of the deposited TC4 were studied. The results show that the microstructure of TC4 and TC4+Nb in deposited state is composed of a large amount of α-Ti and a small amount of β-Ti. With the increase of Nb content from 0 to 8%, the average grain size of the original β-Ti and primary acicular α-Ti in deposited TC4 gradually decreases, and the primary acicular α-Ti size decreases by 67.4%, meanwhile, the basketweave structure is refined and the content of β phase is increased obviously. Nb addition can significantly improve the tensile properties of TC4 deposited specimens. The tensile properties of TC4+6%Nb deposited specimen are the best, which satisfies the standard requirements of forgings.