Correlation between sensitisation and pitting corrosion of AISI 403 martensitic stainless steel

• Effect of tempering temperature on pitting corrosion was investigated.
• The lowest pitting potential was revealed in 550 °C tempered specimen.
• A solution of double loop electrochemical potentiodynamic technique was modified.
• Correlation between pitting and degree of sensitization was revealed.

In this work, the effect of different tempering temperatures on the degree of sensitisation (DOS) and pitting corrosion of AISI 403 martensitic stainless steel is studied. The specimens were annealed at 1050 °C and then tempered at 300, 450, 550, 650 and 750 °C. The influence of sensitisation on pitting behaviour is investigated by electrochemical and microstructural studies. The DOS was measured using modified solution for martensitic stainless steel in double loop electrochemical potentiodynamic (DL-EPR) technique. Electrochemical studies revealed that the highest DOS and the lowest pitting potential are coincided in the specimen tempered at 550 °C.