Study of the influence of molybdenum on the corrosion resistance of ferritic, austenitic and duples stainless steels in pore water simulating alkaline solution and in concrete

Abstract:

To ensure long service life concrete structures, corrosion protection techniques of traditional carbon steel rebars or their replacement for greater corrosion resistant alloys are extensively used. The latter has been used abroad in concrete structures exposed to high aggressive environments, especially in the presence of chloride ions. In this paper, the use of stainless steel rebars is studied, focusing the influence of molybdenum on the pitting corrosion resistance in concrete contaminated with chloride ion. Stainless steel samples were prepared in a laboratory with and without the addition of molybdenum. The chemical composition of these steels was selected based on the chemical composition of commercial stainless steels. Ferritic and lean duplex stainless steels were studied. The lean duplex stainless steels are today a cheap alternative for concrete rebars. Coupons were exposed to alkaline solutions simulating carbonated and noncarbonated concrete pore water both with and addition 3.5 % sodium chloride. The performance of the steels was measured through anodic polarization curves. To validate the results obtained in pore solutions, tests with the steel embedded in carbonated concrete contaminated with chloride ions were also conducted. However, these were not successful because the occurrence of crevice corrosion between the stainless steel coupons and the rein used to delimit the coupon surfaces. The tests in chloride contaminated alkaline solutions clearly showed the positive influence of Mo in the pitting corrosion resistance of the studied steels.


Reference:
MESQUITA, Thiago J.; ARAUJO, Adriana de; PANOSSIAN, Zehbour; NOGUEIRA, Ricardo P.; DIAS JR., Alberto S.; NEVES FILHO, David Neves; DIAS, Sócrates C.S. Estudos da influência do molibdênio na resistência à corrosão de aços inoxidáveis ferríticos, austeníticos e dúplex em solução simulada de água de poro e em concreto. In: CONGRESSO INTERNACIONAL DE CORROSÃO, INTERCORR 2012, 32., 2012, Salvador. Anais… Rio de Janeiro: ABRACO, 2012. 30 p.