Anisotropic tensile and fatigue properties of laser powder bed fusion Ti6Al4V under high temperature

Laser powder bed fusion (LPBF) Ti6Al4V has a great potential to be applied in high temperature vehicle structure. The columnar grains of the LPBF components grow along the build derection. Duo to the specific microstructures, the tensile and fatigue properties of LPBF components are anisotropic. So, the study on high temperature mechanical properties of LPBF Ti6Al4V need to be intestigated further. In this paper, high temperature tensile and fatigue samples were designed and manufactured by LPBF. Tensile tests were carried out at 350 °C, 450 °C and 550 °C. The effects of build direction and temperature on high temperature tensile properties were analyzed and compared. The fatigue tests were carried out at 450 °C, and the strain amplitude was in the range of ±1.5 %. The effects of build direction on the hysteresis loops and the fatigue fracture surfaces of fatigue samples were studied. The results showed that the build direction can affect the kinematic hardening significantly, but it has little effect on isotropic hardening.