Effect of surface finishes on the atmospheric corrosion of duplex grade UNS S32205; Results of a field exposure program in Dubai

The duplex grade UNS S32205 is an excellent choice in many marine environments where UNS S31603 is on the borderline in regards to atmospheric corrosion resistance. The properties of S32205 make it well suited for construction with respect to strength, reduced maintenance, durability and long-term service. In marine environments the use of a sufficiently highly alloyed stainless steel, often in combination with a good surface finish and adequate maintenance, is required to maintain pristine surfaces The main objective with this paper is to present information about the effect of different surface finishes on the corrosion and aesthetic appearance of the duplex grade S32205 exposed at a marine test site in Dubai, UAE. The results obtained include the effect of characteristics such as surface roughness, surface treatment and surface orientation after several years of exposure. Results show that duplex grade UNS S32205 can be considered for architectural materials in severe marine locations such as the Dubai site. A smooth surface and an appropriate surface treatment give improved corrosion resistance. Chromium and silicon in the passive film were found to be beneficial in terms of resistance to aesthetic degradation. A correlation was observed between aqueous corrosion resistance measured in laboratory pitting corrosion tests and the atmospheric field test results.
QC 20161125