Metal Dusting of Low- and High-Alloy Steels

Abstract

Metal dusting is a disintegration of metals and alloys caused by carburization in strongly carburizing atmospheres at carbon activity of (aC) > 1. A dust of fine metal particles and carbon is formed and blown off in erosive gas flows leaving pits or in general abrasion. The kinetics and mechanisms of this phenomenon have been elucidated for iron and low-alloy steels. Protection against metal dusting is possible through the formation of chromia layers on high-alloy steels. These steels can be ranked according to their ability to form a protective layer. The presence of hydrogen sulfide (H2S) in the atmosphere renders protection through sulfur adsorption on surfaces, which retards and suppresses important steps in the reaction mechanism of metal dusting.