Corrosion Fatigue Behavior of Submerged Arc Welded High Strength Steel Used in Naval Structures

Corrosion prevention is a major concern for naval structures particularly for welded joint of high strength steel. Although cathodic protection (CP) is still widely used to prevent corrosion of structural steels in marine environment, effectiveness of CP has not been proven for structural steels with a yield stress above 400 MPa. In the present investigation, high strength steel plate of DMR 249A was welded by Submerged Arc Welding (SAW) process and the corrosion fatigue tests were performed on weld metal in air and 3.5% NaCl solution at room temperature with R ratio of 0.1 and a cyclic frequency of 0.01 Hz with and without cathodic potential. Optimum cathodic potential for weld metal was also evaluated in unstressed condition from the minimum corrosion coefficient among four potentials (under at -800, -875, -950, -1025) mV based on potentiostatic polarization curves (E_corr value) of weld metal. Corrosion fatigue results suggest that optimum cathodic potential data (-875 mV) determined in unstressed condition could be used to improve the corrosion fatigue life of weld metal used in naval structure.