Effects of Heat Treatment Processes on the Microstructure and High-Temperature Mechanical Properties of Ti60 High-Temperature Titanium Alloy

Abstract This paper investigates the effects of various heat treatment processes on the microstructure and high-temperature tensile properties of Ti60 alloy sheets rolled in the α+β two-phase region. By controlling the heat treatment parameters, the material was engineered to exhibit distinct microstructural characteristics, which were analyzed using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The high-temperature mechanical properties of specimens subjected to different treatments were evaluated to establish correlations between microstructure and mechanical performance. The results indicate that specimens subjected solely to aging consistently exhibited a deformed equiaxed microstructure, with texture features remaining similar to those prior to aging. High-temperature strength increased with higher aging temperatures and longer aging durations, with yield strength improving by 40–100 MPa. In contrast, specimens subjected to solution treatment followed by aging displayed a bimodal microstructure consisting of equiaxed α and lamellar α phases. The texture evolved from a duplex B-texture to a single B-texture, accompanied by a gradual decrease in strength, with yield strength declining by approximately 50 MPa. Analysis suggests that during aging alone, the precipitation of nanoscale α 2 ordered phases increased with prolonged isothermal exposure and elevated temperatures. The strengthening effect of these nanoscale precipitates significantly enhanced the high-temperature yield strength. In the solution treatment plus aging process, increasing the solution temperature reduced the content of equiaxed α phase and increased the effective grain size, thereby diminishing grain boundary strengthening. Consequently, the yield strength notably decreased during high-temperature sustained deformation.