Austenitic Alloys in Sulfidizing Corrosive Atmospheres with Low Levels of Oxygen Activity and High Levels of Carbon Activity: Creep Behavior.

Certain very aggressive industrial atmospheres, notably those of coal gasification processes, are characterized by very low levels of oxygen activity and high levels of carbon and sulfur activity. The only materials available at present for use in such atmospheres are the austenitic alloys. A study is therefore presented of the influence of creep on the corrosion of Alloy 800H and AISI 316L steel in coal gasification atmospheres. The apparatus for testing creep in a gaseous corrosive atmosphere is described, together with the first results obtained for the materials. The creep rate for Alloy 800H is increased compared with that found in tests in air. The thickness of the layers of corrosion increases under stress because of cracking of the Cr//2O//3 barrier.