Erosion-Corrosion Behavior of Some Cast Alloys in Seawater

Abstract

Abstract The corrosion behaviors of high-chromium duplex cast steel, high-silicon, nodular, and nickel-resist cast iron were studied in stagnant and flowing seawater (flow velocities of 2.5, 5.4, and 8.3 m/s). The experiments involved measurements of the mass loss and examination of the corrosion morphology. The duplex stainless steel did not experience corrosion and/or erosion damage. The high-silicon cast iron exhibited excellent erosion-corrosion resistance but was susceptible to pitting attack only under stagnant and relatively low-flow conditions. The attack occurred at the boundaries of graphite flakes and interdendritic carbides. Both the nodular and nickel-resist cast irons suffered from erosion-corrosion damage that was more severe in the former alloy. Under stagnant conditions, the corrosion rates were very low for both alloys, and thin scales were observed. However, under flow conditions, relatively thick scales were formed showing patterns of seawater flow. There was a sharp increase in the co...