Enhancing the creep resistance of electron beam melted gamma Ti–48Al–2Cr–2Nb alloy by using two-step heat treatment

Electron beam melted Ti–48Al–2Cr–2Nb alloy has undesirable creep resistance due to a near-gamma structure that is not proper for creep. We aimed to control the microstructure of EBM-built Ti–48Al–2Cr–2Nb using two-step heat treatment to improve the high-temperature (750 °C) creep resistance while also maintaining room-temperature ductility. As a result of two-step heat treatment, heat-treated EBM-built Ti–48Al-2r-2Nb alloy has a nearly lamellar microstructure with a thin lamellar structure and fine equiaxed gamma grains. High-temperature creep resistance was significantly improved after two-step heat treatment by inducing a thin lamellar structure. Room temperature ductility was also maintained even while containing a lamellar structure. [Display omitted] •Two-step heat-treated EBM-built Ti4822 shows nearly lamellar microstructure with equiaxed gamma and thin lamellar structure.•Room temperature ductility was maintained even though the Vickers hardness increased significantly from 252.8 HV to 402.5 HV•High temperature creep resistance is successfully improved after two-step heat treatment.