High-Temperature Corrosion Resistance of Ti-555 Titanium Alloy after Equal Channel Angular Pressing and Heat Treatment

This paper used Ti-5.4Al-4.1Mo-5 V-3Cr-1Zr (Ti-555) as the study material, and secondary processing methods consisting of the combination of equal channel angular pressing (ECAP) and heat treatment were adopted. The effect of different processes such as 820/880 degrees C solid solution-580 degrees C aging, 820 / 880 degrees C solid solution-ECAP-580 degrees C aging, and ECAP-820/880 degrees C solid solution-580 degrees C aging on the high-temperature corrosion behavior of the alloy was studied in 75 wt.% NaCl + 25 wt.% Na2SO4 at 800 degrees C for 40 h. The corrosion characteristics of the alloy were evaluated via scanning electron microscope (SEM), optical microscope (OM), and x-ray diffraction (XRD). The result shows that the weight gain curve tends to be stable after 35 h, and the lowest weight gain was observed in the alloy treated at 880 degrees C solid solution-ECAP-580 degrees C, which is 0.88 mg center dot cm(-2). The corroded surface is mainly composed of TiO2 and Al2O3. The thickness of the corroded section of the titanium alloy aged at 820/880 degrees C solid solution-ECAP-580 degrees C is 70 and 50 mu m, respectively. Overall, the best high-temperature corrosion resistance of the Ti-555 alloy was obtained when subjected to 880 degrees C solid solution-ECAP-580 degrees C aging treatment.