Anisotropy in microstructure and tensile properties of Ti-5Al-5Mo-5V-1Cr-1Fe produced via additive manufacturing

This work investigated macroand microstructure and tensile properties of Ti-5Al-5Mo-5V-1Cr-1Fe fabricated using electron beam rapid manufacturing (EBRM). The macrostructure contained columnar prior beta grains and layer bands with gradient microstructures, which could be attributed to the large temperature gradient along the vertical direction (VD) and the multiple cycles of thermal history. The dendritic morphologies formed below the layer bands due to element micro-segregation. The microstructure in the top zones of the specimen was asso-ciated with the local cooling rate depending on the building morphology. There were obvious anisotropic tensile properties for the alloy. The sample loaded along the VD presented lower tensile strength with respect to that along the horizontal direction (HD), whereas there was a maximum tensile strength for the sample loaded along the 45 degrees direction. The ductility of the alloy displayed an opposing trend relative to the tensile strength. We respectively discussed the effects of the columnar beta grain, the beta < 100 >//VD fiber texture, and the transformed alpha texture on the tensile properties. We also proposed that the anisotropic tensile strength was mainly caused by the transformed alpha texture, and the anisotropic ductility was associated both with the columnar beta grain and the transformed alpha texture.