Surface integrity engineering via ultrasonic surface rolling for enhanced hot salt stress corrosion cracking resistance of TC11 alloy

Ultrasonic surface rolling processing (USRP) was applied to TC11 titanium alloy to improve its resistance to hot salt stress corrosion cracking (HSSCC) under high-temperature constant-load tensile conditions. By tailoring the number of processing passes, USRP produced a refined surface finish and introduced a thermally stable compressive residual stress (CRS) field. The CRS stability was maintained through the pinning and entanglement of high-density dislocations, effectively suppressing stress relaxation during thermal-mechanical exposure. The smoother surface reduced local stress concentrations and limited CRS redistribution. In addition, USRP promoted the rapid development of a dense amorphous–nanocrystalline composite oxide film, which served as an effective barrier to corrosive species and mitigated oxygen-induced embrittlement. These combined effects markedly enhanced the HSSCC resistance of TC11 alloy, demonstrating the potential of USRP as a robust surface engineering technique for extending the service life of titanium alloys in aggressive high-temperature salt environments. • USRP improves the HSSCC resistance of TC11 alloy at 500 °C. • Stabilize CRS and smooth surface to enhance crack resistance. • Dislocation structures help maintain CRS under thermo-mechanical conditions. • CRS and dislocations promote formation of a dense protective oxide film. • The nanocrystalline–amorphous oxide layer inhibits Cl/O diffusion effectively.