HIGH TEMPERATURE CORROSION BEHAVIOR OF STAINLESS STEELS IN EXHAUST GAS FROM AUTOMOBILE ENGINES.

The purpose of the investigation was to supply data on which selection of materials for automobile emission control devices could be based. Stainless steels known to have relatively high oxidation resistance were tested in the atmospheres of exhaust gas from automobile engines at high temperatures, and the mechanism of high temperature corrosion observed was analyzed. Oxidation in exhaust gases was accelerated compared with oxidation rates in air. By calculating the sulfur potential of the CO-CO//2-COS-SO//2-S//2-O//2 exhaust gas system, it is concluded that oxidation by CO//2, H//2O, and O//2 in the exhaust gas at high temperatures is accelerated by sulfur via the formation of sulfur compounds (such as iron, chromium, and nickel sulfides) between the oxide scale and the base metal.