Development of Low Alloy Seawater Corrosion Resistant Steel

Three kinds of Cu-Mo and Cu-Mo-Cr alloyed steels were designed and melted,and then hot rolled into20mm thick plates,and finally mechanical property,seawater corrosion resistance and weldability of the rolled plates were evaluated.Salt spray tests with 96,240,336and 500hours were conducted,and all tested steels shows improved corrosion resistance as compared to SM490A,and the superior corrosion resistance is more pronounced with elongation of testing period.Corrosion resistance increases with increasing Cr content,and the corrosion resistance of the steel with 0.85% Cr increases 59.1%as compared to SM490A.The Cr enriched at inner rust layer can effectively withstands diffusion of Cl-,and thus improves corrosion resistance.Gleeble simulation was executed to evaluate steel weldability without preheating and postweld heat treatment,and the impact toughness of the simulated CGHAZ≥57Jwith cooling rates of 5-60℃/s,which implies the good weldability of the designed steel.