Analysis of the Corrosion Behavior of Welding Joint of SA210 Steel Used for High-pressure Evaporator Tubes in Heat Recover Steam Generator

To analyse the corrosion behavior of welding joint of SA210 steel used for high-pressure evaporator tubes in heat recover steam generator (HRSG),the corrosion resistance of welding joint and base of SA210 steel was analyzed by metallographic analysis and electrochemical study. The microstructure of welding joint and base of SA210 steel was observed and the polarization curves of its welding seams,fusion line,welding HAZ and base in 0.2 mol/L NaCl solution were measured. It turned out that the corrosion current of the fusion line in SA210 steel was much higher than that of other parts. The results indicate that preferential corrosion will develop along the fusion line of SA210 steel owing to the coarse grain,uneven microstructure and chemical composition and the widmannstatten structure.