Atmospheric Corrosion of Stainless Steel of Type 18Cr–2Mo–Ti

Abstract

Test specimens of steels of type 18Cr–2Mo–Ti and, as reference materials, AISI 304 and 316, were exposed for 5 years to an urban atmosphere and to a marine atmosphere. All steels were tested in three different surface conditions produced by pickling, grinding and mechanical polishing, respectively. The specimens were examined visually after 1, 3 and 5 years, and by SEM at the end of the tests. It was concluded that: (1) in an urban atmosphere all combinations of steel and surface condition were fully acceptable; (2) in a marine atmosphere the 18Cr–2Mo–Ti steel proved to be slightly better than type 316, which in turn was markedly better than type 304. The polished surfaces were, on average, superior to pickled surfaces, which were in turn slightly better than ground surfaces. Where rust was revealed, it was formed mainly during the first year of exposure. All steels were subject to superficial pitting attack, regardless of surface condition.

It was concluded that stainless steel of type 18Cr–2Mo–Ti is very well suited for use in building applications in cities and near coasts. This is valid for pickled, ground or mechanically polished surfaces.