Degradation of AISI304 stainless steel by atmospheric exposure in Saudi Arabia

Stainless steel grade AISI304 is the largest tonnage alloy material used for industrial and domestic purposes in Saudi Arabia. The primary property, which determines its use in many applications, is its corrosion resistance in a wide variety of aqueous environments. The aim of this study is to evaluate the joint effect of marine and industrial pollutants on the atmospheric degradation of AISI304. The corrosion rate of specimens was determined after one, two, three and four years of exposure by weight loss. The time of wetness and deposition rates of atmospheric pollutants (Cl- and SO2) was also determined. The ISO 9223 standard for atmospheric aggressivity has been applied to the different test sites used. The results agreed well with the empirical kinetics equation of the form C=Kt(n), where K and C are the corrosion losses in mg cm(-2) after 1 and t years of the exposure respectively, and n is constant. Based on n values, the corrosion mechanism of AISI304 is predicted. Characterisation of the corrosion product layers was performed using X-ray diffraction. The results obtained show that the corrosion rate of AISI304 is a function of the chloride, SO2 pollution level and time of wetness.