Effect of trace amounts of S on the steam oxidation behavior for mod.9Cr-1Mo steels

Abstract

The oxidation behavior of six heats of Modified 9Cr-1Mo steel has been investigated in steam at four temperatures between 873 and 1023K for up to 3.6 Ms, comparing with that of 9Cr-0.5Mo-1.8W-V-Nb steel and 11Cr-0.4Mo-2W-Cu-V-Nb steel. The difference of weight gain due to steam oxidation among the six heats of Modified 9Cr-1Mo steel is not large at a low temperature of 873K, but it becomes more significant with increasing test temperature. The heats containing higher sulfur exhibit smaller weight gain than those containing lower sulfur and also than other steels examined. It is concluded that a good resistance to steam oxidation of Modified 9Cr-1Mo steel is closely correlated with higher sulfur content.