Comparative Study Between Sensitization Degree of the 0.4% Mo Austenitic Stainless Steel and UNS S31803 Duplex Stainless Steel

This study aims at assessing the degree of susceptibility to intergranular corrosion of the UNS S31803 duplex stainless steel and the 0.4% Mo austenitic stainless steel through the double-loop electrochemical potentiodynamic reactivation (DL-EPR) test. Both steels were subjected to isothermal treatments at 650ºC and 900ºC in order to compare the effect of temperature on the respective degrees of sensitization. It was observed that the 0.4% Mo austenitic stainless steel presented a higher degree of sensitization and, consequently, a greater susceptibility to the intergranular corrosion process when compared to the UNS S31803 duplex stainless steel in the two temperatures studied. It was also observed that, for both steels, the heat treatment at 900ºC resulted in a higher degree of sensitization when compared to the heat treatment at 650ºC.

本研究旨在通过双环动电位再活化（double-loop electrochemical potentiodynamic reactivation, DL-EPR）试验，评估UNS S31803双相不锈钢与0.4%钼（Mo）奥氏体不锈钢的晶间腐蚀敏感程度。两种钢材均分别在650℃与900℃下实施等温处理，以对比温度对二者各自敏化度的影响。试验结果表明，在两个研究温度下，相较于UNS S31803双相不锈钢，0.4%Mo奥氏体不锈钢的敏化度更高，因此其晶间腐蚀敏感性也更强。此外还观察到，对于两种钢材而言，900℃热处理后的敏化度均高于650℃热处理后的敏化度。