Effect of Heat Treatment on the Fatigue of Laser‐Powder Bed Fused Ti‐6Al‐2Sn‐4Zr‐2Mo Alloy

ABSTRACT This study investigates the effect of heat treatment on the monotonic and fatigue behavior of laser‐powder bed fused Ti‐6Al‐2Sn‐4Zr‐2Mo. The as‐built microstructure consists of acicular α’ martensite, featured with dense dislocations that result in high strength and low ductility. To preserve the microstructure and achieve strength–ductility synergy, a two‐step sub‐transus heat treatment is selected: solutionizing (ST) below the β‐transus temperature and aging (STA). The ST heat treatment results in the evolution of α/α’ and β phases, with good strength–ductility synergy. The STA treatment causes the dislocations to rearrange, accompanied by a slight strength enhancement. The STA condition showed a small improvement in fatigue life in the high‐cycle regime but demonstrated minimal changes compared to the as‐built condition for low‐ to mid‐cycle regions. The low and mid‐cycle fatigue life of as‐built and STA conditions showed noticeably similar results to wrought Ti‐6Al‐4V fatigue behavior.