Effect of plasma electrolytic oxidation on the hot salt corrosion fatigue behavior of the TC17 titanium alloy

Abstract In this paper, the effect of plasma electrolytic oxidation (PEO) on the hot salt corrosion fatigue (HSCF) behavior of the TC17 titanium alloy at 420°C was investigated. Through microstructure characterization and fatigue fracture analysis, combined with a comparative study of its hot salt corrosion behavior, the mechanism of PEO on HSCF behavior was also investigated. The results showed that the high‐temperature fatigue resistance of the TC17 titanium alloy was significantly reduced by the deposition of 0.4 mg/cm 2 of solid NaCl compared with that without a salt coating. This behavior was observed because the corrosion pits caused by hot salt corrosion promoted the initiation of fatigue cracks, and hydrogen penetration promoted the growth of fatigue cracks. However, the HSCF resistance of the TC17 alloy with the PEO ceramic coating could be effectively increased. This was because the PEO ceramic coating with high bonding strength and good compactness effectively inhibited hot salt corrosion damage and delayed the formation of the resident slip zone and hydrogen permeation, thereby inhibiting the initiation and propagation of fatigue cracks.