Hot salt corrosion behavior of Ti–6Al–4V alloy treated with different surface deformation strengthening processes

In this study, the effects of shot peening (SP) and ultrasonic surface rolling process (USRP) on the high-temperature oxidation and hot salt corrosion (HSC) behavior of the Ti–6Al–4V alloy were systematically investigated. The results showed that the high-temperature oxidation resistance of this titanium alloy can be significantly improved by the above two treatments. However, the hot salt corrosion resistance of Ti–6Al–4V alloy cannot be improved by SP due to surface roughness increasement, the surface defects and the complete relaxation of compressive residual stress (CRS) at high temperature. On the contrary, the hot salt corrosion resistance of USRP treated specimen was remarkably improved because USRP treatment significantly reduced the surface roughness and introduced deep CRS field with good thermal stability. In addition, the refined surface microstructure promoted the formation of a protective oxide film, which was also beneficial for inhibiting hot salt corrosion.