Grain structure control of a novel titanium alloy during laser powder bed fusion by processing

The characteristic of rapid solidification in additive manufacturing can address the challenge of brittle fracture caused by the segregation of O and Fe atoms in titanium alloys. This paper studied the effects of process parameters of L-PBF and heat treatment on the microstructure and mechanical properties of Ti-0.4O-3Fe alloy. The research indicated that equiaxed prior-β grains were obtained at a low energy density (91J/mm 3 ), while columnar prior-β grains were obtained at a high energy density (164J/mm 3 ). Meanwhile, the α' martensite of less than 1 μm in size and GB-α were distributed in the intracrystalline and grain boundaries of the prior-β grains, respectively. The as-fabricated state of the L-PBF process exhibited high strength but compromised ductility. After annealing at 600°C for 2 hours, excellent strength-ductility matching was achieved, with a yield strength and tensile strength of 91 J/mm 3 reaching 1061.9 MPa and 1112.2 MPa, respectively, and a fracture strain of 13.21%; the yield strength and tensile strength of 164 J/mm 3 reach 1028.8 MPa and 1063.7 MPa, respectively, with a fracture strain of 10.97%.