Influence of ferritic nitrocarburizing on the high-temperature corrosion-fatigue properties of the Si-Mo-Al cast iron SiMo1000

摘要

The influence of ferritic nitrocarburizing on the high-temperature corrosion-fatigue properties of the Si-Mo-Al cast iron SiMo1000 is investigated in the present study. It was found that nitrocarburizing effectively increases the surface hardness, but dramatically decreases the fatigue and oxidation resistance of SiMo1000. The fatigue resistance is reduced due to two types of microcracks formed after nitrocarburizing. The oxidation resistance is dramatically diminished due to the formation of microcracks, and the depletion of aluminum in the matrix from nitride precipitation during the exposure at 800 °C. The corrosion-fatigue synergy is found to cause severe decarburization (i.e. graphite depletion) in nitrocarburized SiMo1000.