Corrosion resistance of low-nickel duplex stainless steel rebars

The use of stainless steel bars in reinforced concrete structures may be an effective method to prevent corrosion in aggressive environments where high amounts of chlorides may penetrate in the concrete cover. For an estimation of the service life of structures where stainless steel bars are used, the chloride threshold for these rebars should be defined, and the influence of chemical composition and metallurgical factors that may affect the corrosion resistance (strengthening, welding, etc.) should be assessed. To reduce the cost of stainless steel reinforcement, duplex stainless steels with low nickel content have been recently proposed as an alternative to traditional austenitic steels, even though, few results are available regarding their corrosion performance in chloride contaminated concrete. This paper deals with the corrosion resistance of low-nickel duplex stainless steel rebars (1.4362 and 1.4162) as a function of the chloride content. Comparison is made with traditional austenitic steels. An attempt to define a chloride threshold for the different stainless steels is made by comparing the results of several test procedures both in concrete and in solution.