Effect of Solution Temperature in β Phase Forging Process on Dwell Fatigue Properties of Ti6242 Alloy

The Ti6242 titanium alloy was processed by β phase forging at different solution temperatures (960,980 ℃), and the microstructure and tensile properties of the alloys under different solution temperatures, as well as low cycle fatigue and dwell fatigue properties under high peak stresses were studied. The results show that the microstructures of Ti6242 alloy after β phase forging at different solution temperatures were similar, and consisted of net basket structure, in-grain α layer structure and feather α phase cluster structure. The feather α phase phase cluster at solution temperature of 960 ℃ was more than that at solution temperature of 980 ℃. Compared with those by β phase forging at solution temperature of 960 ℃, the strength of the alloy processed by β phase forging at solution temperature of 980 ℃ was higher, the percentage elongation after fracture was slightly lower, the low-cycle fatigue life was obviously lower, and the dwell fatigue sensitivity coefficient was lower; the dwell fatigue life at solution temperature of 980 ℃ was about 1.3 times of that at solution temperature of 960 ℃. The low-cycle fatigue fracture after β phase forging at different solution temperatures had the obvious fatigue characteristics, and consisted of fatigue crack source, fatigue crack propagation zone and transient fracture zone. The dwell fatigue fracture was composed of dimples and fatigue bands, and the fracture mode was dominated by creep fracture and supplemented by fatigue fracture.