Corrosion characteristics of HSLA steels in sea water

Corrosion behaviours of two HSLA-100 steels designated as GRV (having higher Cu and Ni content) and GPQ (having lesser amount of the above mentioned elements) have been studied in sea-water. It is observed that in aggressive and stirred environments, GRV performs superior than the GPQ steel. Electrochemical tests, surface topographic studies and weight loss experiments have shown that Cu and Ni added in the alloys have a strong role in controlling the corrosion reaction. A model have been proposed for the onset and propagation of corrosion of HSLA steels in marine environment, Some experimental proofs have been generated to supplement the proposed model. The, microstructure of another steel (GPP) which is equivalent to GRV steel (in respect of alloying elements) was varied by quenching and termpering (Q&T) and its corrosion rate was evaluated. No effect of microstructure was noted on corrosion rate of the steel. Atmospheric corrosion rate for GRV and GPQ steel exposed in marine atmosphere near sea-shore of Digha (Bay of Bengal) exhibits almost identical corrosion rate