Effect of Cooling Rate of Solution Treatment on High-Temperature Creep Properties of Ti60 Alloy Rolled Plate

Abstract: Solution aging treatment is the main strengthening method to improve the properties of Ti60 alloy. However, the high-temperature creep behavior and microstructure of Ti60 alloy are extremely sensitive to the cooling rate during high-temperature solution treatment. Therefore, to investigate the effect of microstructural changes caused by cooling rate on creep strain rate and fracture life, this study conducted high-temperature tensile creep tests at 650 °C–200 MPa on Ti60 alloy rolled plates with different cooling rates of solution treatment. It was found that the slower the cooling rate, the longer the creep life. Compared with the origin Ti60 alloy, the creep life of samples treated by water cooling, air cooling, and furnace cooling after solution treatment increased from 17.9 h to 150.8 h, 319.9 h, and 498.8 h, respectively. It was also found that slow cooling (furnace cooling) facilitates the comprehensive development of α phase, reduces high-angle grain boundaries, and forms coarser lamellar grains, thereby significantly improving the creep performance of the material. In contrast, fast cooling (air cooling) produces abundant ∑33c twin boundaries, which promote grain boundary sliding, rotation, and atomic diffusion. This not only accelerates the initiation of microcracks but also serves as the starting point for material failure.