Study on the Microstructure and Mechanical Property Anisotropy of Ti6242S-0.75Ni-1.65Fe-0.05B Alloy by Laser Direct Energy Deposition

Author of the article:YUAN Lukai1,2, WANG Lilin1,2, DING Hanlin1,2, XUE Aitang1,2, LIN Xin1,2, HUANG Weidong1,2

Author's Workplace：1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China; 2. MIIT Key Laboratory of Metal High Performance Additive Manufacturing and Innovative Design, Northwestern Polytechnical University, Xi'an 710072, China

Key Words：laser direct energy deposition; composition regulation; microstructure; mechanical performance; anisotropy

Abstract：Due to the epitaxial growth of coarse columnar β grains, additive manufactured titanium alloys show significant mechanical anisotropy. Composition regulation is an important means to improve the anisotropy of additive manufactured titanium alloys through a columnar to equiaxed transition. Because of the precipitation of brittle intermetallic compounds, there exists a contradiction between fully equiaxed grains and good plasticity. Different from conventional single element alloying, the full-equiaxed β grains of Ti6242S-0.75Ni-1.65-Fe-0.05B alloy are achieved by laser direct energy deposition (DED) with additions of Ni, Fe and B elements through calphad, and the formation of intermetallic compounds is avoided. The tensile properties at room temperature show that the mechanical anisotropy of the Ti6242S-0.75-Ni-1.65Fe-0.05B alloy is basically eliminated, and the strength and plasticity of the Ti6242S-0.75-Ni-1.65Fe-0.05B alloy are higher than those of the Ti6242S alloy in the transverse and longitudinal directions.