In order to study the effects of alloying elements on corrosion resistance of high alloy steels in a simulated environment of waste incinerator, laboratory corrosion tests were performed on high alloy steels with various contents of Cr and Mo. It was found that the rate of general corrosion decreased with the increase of the Cr+Mo content and the rate of maximum penetration, which was the sum of intergranular penetration rate and general corrosion rate, decreased with the increase of the Mo content in this condition. The type of corrosion shifted from the intergranular penetration to the general corrosion over 5 mass%Mo. It was assumed that Mo in the alloys acted to restrict the sulfidation of Ni and to accelerate the formation of the protective Cr2O3 layer.
