High Temperature Corrosion Properties of Heat Resistant Chrome Steels in SO_2 Atmosphere

摘要

The high temperature corrosion properties of heat resistant steels were investigated in oxidation atmosphere including sulfur dioxide. The heat resistant steels of T22, T92, T122, T347HFG and T304H were evaluated at 620, 670 deg C for 400 hours. The corrosion rates showed a decreasing tendency while chrome contents of those steels increased from 2 mass. percent to 19 mass. percent. The in crease in temperature increasement has an more effect on the corrosion rates of low chrome steels than high chrome steels. The weight gains of T22, T92, T304H at 670 deg C were 3.7, 1.65, 1.23 times compared with those at 620 deg C. The external scale formed on T22 was composed of hematite, magnetite and Fe-Cr spinel and internal layer including iron oxide mixed with sulfide. The scales formed on T92, T122, T304H consisted of an outer layer of hematite and inner layer of chrome oxide and hematite. The proportion of chrome oxide at inner layer was increased when the chrome contents in heat resistant steels were increased.