Evaluation of resistance to corrosion by pitting of stainless steel duplex SAF 2304

It was evaluated the corrosion resistance of a duplex SAF 2304 stainless steel. Pitting corrosion tests were carried out under ASTM G48-03 at a temperature of 50 degrees C for 72 hours in ferric chloride at 6% concentration and electrochemical polarization tests under ASTM G5-87 at a temperature of 22 degrees C for 0.5hrs in sodium chloride at 3.5% concentration. 9 cylinders samples of stainless steel SAF 2304 duplex were used, 6 samples for the pitting corrosion test and 3 samples for the electrochemical polarization test. Weight loss analysis, macroscopy, optical microscopy and Vickers Microhardness were performed. In the electrochemical test the value of the anodic slope turned out to be very high, in the sting tests where the formation of passive films on the surfaces of the samples tested, a process of localized corrosion could be appreciated with the presence of large amount of pitting. It was observed a localized deterioration in the interphases austenite-ferrite phases, with presence of pitting. The corrosion rate presented a variation similar to that obtained for the weight loss, which demonstrated the heterogeneity of the material.