Effect of Sensitization on the Chromium Ion Released from 430 Ferritic Stainless Steel

The effect of heat treatment temperature on the sensitization of 430 stainless steel and the effect of sensitization on the precipitation of 430 stainless steel in corrosive solutions were investigated by microscopic observation and electrochemical methods. The results show that when the heat treatment temperature was 800-900 ℃, the sensitization degree of the sample increased with the increase of temperature, and it was most serious at about 900 ℃. Continue to increase the heat treatment temperature, the sample grain growed, the intergranular corrosion area became smaller, and the sensitization degree decreased. In acidic chlorine-free or chlorine-containing neutral solutions, the sensitization degree of the sample had little effect on the amount of chromium precipitation. In acidic chloride-containing solution, the amount of chromium ion precipitated was large and increased with the increase of sensitization degree. The amount of chromium ion precipitated on the first day of sensitization of the sample was relatively high. With the extension of time, the total amount of chromium ion in different solutions increased cumulatively, but the daily average increase was not the same. The rise of solution temperature accelerated the corrosion of sensitized sample in corrosive solutions, so that the amount of chromium ion precipitation increased.