Evaluation of Self-Healing Behaviour of AISI 304 Stainless Steel

摘要

AISI 304 stainless steel (SS) is used in applications like automotive, oil, gas and the food industry due to its excellent combination of corrosion resistance and mechanical properties. However, due to sensitisation, its corrosion resistance reduces, rendering it more vulnerable to inter-granular corrosion. Prolonged ageing in the sensitisation temperature range (450-850 A degrees C) shows signs of restoration of corrosion resistance. This self-healing behaviour can be attributed to subsequent reduction of the chromium-depleted zones. This work focuses on thermal ageing of AISI 304 stainless steel at 750 A degrees C for various time durations up to 960 h. The extent of sensitisation and de-sensitisation were analysed, qualitatively by metallographic inspection and quantitatively by electrochemical techniques. The highest degree of sensitisation was 42.74 % for sample heat treated for 96 h, after which the initiation of restoration of corrosion resistance was observed. These results were further confirmed by electron probe micro-analyser studies.