ABSTRACT
The aim of the study was to determine the corrosion behavior of two austenitic stainless steels, AISI 304L and AISI 316Ti, after cold rolling (AR) and mechanical polishing/grinding (MP), in a 32% aqueous solution of AUS (RSM®) Ammonium Nitrate/Urea Solution, used as fertilizer, and compared with the corrosion resistance results obtained in 3% aqueous solution of sodium chloride (NaCl). The studies have shown that cold rolled austenitic stainless steels (AISI 304L and AISI 316Ti) in the 32% aqueous solution of AUS have more than two times higher pitting corrosion resistance than that obtained in 3% aqueous solution of sodium chloride (NaCl). Surface scratch of the cold rolled austenitic AISI 304L stainless steel and submersion of the samples in 3% aqueous solution of sodium chloride resulted in decreasing of its pitting corrosion resistance of more than three times; on the other hand, the pitting corrosion resistance of AISI 316Ti in the same solution decreased of two times. It was found that for both stainless steels (AISI 304L and AISI 316Ti) after mechanical grinding, as simulated by the surface scratch, and submersion of the samples in 32% aqueous solution of AUS, the pitting corrosion resistance was not worsened, because of the passivation properties of AUS solution. The study results have shown that in the natural environments containing aqueous solutions of sodium chloride (NaCl), the use of austenitic stainless steel containing chromium, nickel, molybdenum and titanium (AISI 316Ti) is advised. In other environments without chlorides, such as the AUS fertilizer, the use of austenitic AISI 304L stainless steel may be considered as adequate.
References
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