Effects of hot isostatic pressing on microstructure and tensile properties of direct laser deposited Ti60 alloys

Ti60 alloys were fabricated by using direct laser deposition (DLD) technology and it was studied that the effects of hot isostatic pressing (HIP) on defects, microstructure and tensile properties of the DLD Ti60 alloys. The results show that there are two typical kinds of defects in the DLD Ti60 alloys, which are pores and lack of fusion. After HIP treatment, pores and the small size of lack of fusion are eliminated. There are columnar crystals at the bottom and the middle of the as-deposited specimens, but at the top of the specimens are equiaxed grains. The microstructure is widmanstatten structure, which is composed of alpha laths and beta between the laths. After HIP and double annealing treatment, the grain boundary alpha melting, the most of the original beta grain boundaries disappear, alpha laths coarsening, the length-width ratio decreases, and the microstructure becomes basket-weave microstructure. Compared with the forgings, the as-deposited specimens have a high tensile strength with a low plasticity, after HIP and double annealing treatment, the plasticity of the as-deposited specimens exceeds the standards of the forgings.