In situ neutron diffraction study of strain evolution and load partitioning during elevated temperature tensile test in HIP-Treated electron beam powder bed fusion manufactured Ti-6Al-4V

Pandian, K.*; Neikter, M.*; Ekh, M.*; Harjo, S.   ; Kawasaki, Takuro   ; Woracek, R.*; Hansson, T.*; Pederson, R.*

To produce dense Ti-6Al-4V components, electron beam powder bed fusion is typically followed by post-heat treatment like hot isostatic pressing (HIP). Standard HIP at 920C/100 MPa for 2 h coarsens the microstructure and reduces yield strength, while low-temp HIP at 800C/200 MPa for 2 h limits coarsening and retains strength comparable to as-built material. A coarser microstructure negatively affects tensile properties. Tensile tests at various temperatures suggest that thermally activated slip systems may influence elongation, requiring further study. In situ neutron time-of-flight diffraction during tensile loading enables analysis of strain evolution and slip plane activity. A two-phase elastic-plastic self-consistent model was used to compare with experiments. Results show basal slip {0002} activated at 20C, pyramidal slip {10-11} at 350C, and phase carrying higher stress than in the plastic regime.