Effects of thermal undercooling and thermal cycles on the grain and microstructure evolution of TC17 titanium alloy repaired by wire arc additive manufacturing

Wire arc additive manufacturing (WAAM) can be used to repair blades or blisk made of titanium alloy with the advantage high efficiency and low-cost. In this work, finite element model repairing blade based on heat source was established investigate it. Results showed that maximum effect thermal undercooling appeared when peak current transformed base (1 Hz 5 Hz), which will promote grains refinement combination sufficient constitutional supercooling. Compared single-layer deposition, microstructure in near-heat affected zone (near-HAZ) multi-layer deposition changes from metastable β phases extremely fine α phases, caused by repeated cycles.