The thermal treatments employed in alloys are essential to obtaining desired microstructures and corrosion resistance properties. In this paper the low carbon martensitic steel 13Cr4Ni0.2C with different tempering temperatures was studied using potentiodynamic polarization technique in synthetic marine environment, in order to evaluate the effect of the tempering temperature on the steel corrosion resistance in an environment that simulates the conditions of use in oil and gas production. Microscopy results showed differences in the microstructure of tempered steel at low (620°C) and high (770°C) temperatures, indicating the appearance and extending of martensite laths with increasing temperature. Polarization tests showed that tempering temperature located between 620°C and 710°C indicated passive film formation and tempering temperatures of around 620 °C showed better resistance values to pitting corrosion.

This study aimed to investigate the effects of difference in nickel content and the tempering temperatures on the corrosion resistance in 13Cr2Ni0.1C and 13Cr1Ni0.15C steels. Results showed that passive film in 13Cr2Ni0.1C steel is formed more quickly at the lowest and highest tempering temperature (650°C and 750°C) but the lowest tempering temperature (650°C) showed better resistance to corrosion pitting. There was passive film formation and pitting corrosion in all tempering temperatures of the 13Cr1Ni0.15C steel and changes in tempering temperature does not significantly alter polarization curves, showing similar behavior to steel 13Cr2Ni0.1C tempered at 650°C.