The Corrosion Characterization in Simulated Heat-Affected Zones of X80 Pipeline Steel in Near-Neutral Solution

摘要

The microstructure evolution and corrosion characterization under elastic stress in near-neutralchloride bearing solution of X80 pipeline steel simulated heat-affected zone (HAZ) were studied. It isshown that the corrosion resistance in fine grain HAZ (FGHAZ) is the best which can be attributed tothe fine grains and the uniform distribution of M/A islands. In addition, the corrosion resistance ofcoarse grain HAZ (CGHAZ) with high peak temperature is the weakest which can be attributed to thecoarse microstructure. In addition, relatively high heat input should be taken to improve the corrosionresistance in CGHAZ. It is found that four couples of galvanic effects exist at least which can promotethe occurrence of localized corrosion. The presence of two obviously different parts in corrosionmorphologies and the presence of pitting holes which locate in M/A islands sites on base material andCGHAZ surfaces can be attributed to the galvanic effects.