Metal dusting: relationship between alloy composition and degradation rate

Abstract

The authors have identified a compositional relationship between several commercially available wrought alloys, focussing only on the iron, nickel, chromium and aluminium content. The degradation rate due to metal dusting varies with the surface condition of each alloy: a ground surface condition corresponds to smaller mass losses than a pickled surface condition. The authors have derived a relationship between the maximum observed degradation rate due to metal dusting and the chromium plus aluminium content of each alloy. This relationship has been verified by comparing data from several exposures using different gas compositions and pressures. The results indicate that for the gas used in this exposure, the degradation rate strongly decreases up to a chromium plus aluminium content of 33 wt-%. Above this value, the mass loss rate is negligible. The current relationship is also found valid for aluminide diffusion coatings.