Effect of temperature on the corrosion behaviour of low-nickel duplex stainless steel bars in concrete

Stainless steel reinforcing bars can be a means for prolonging the service life of reinforced concrete structures exposed to tropical climates. To select a suitable grade of stainless steel according to exposure conditions and design service life, the definition of the chloride threshold for pitting corrosion initiation is required. This paper investigates the effect of temperature in the range 20–60 °C on the resistance to chloride-induced corrosion of low-nickel duplex stainless steel rebars and, for comparison, of traditional austenitic stainless steel rebars. Tests in concrete and in solutions simulating the concrete pore liquid were performed and an attempt to evaluate the chloride threshold levels for corrosion initiation was carried out. Results showed lower corrosion resistance and higher sensitivity to increase in temperature for low-nickel duplex stainless steel bars compared to traditional austenitic stainless steels.