Research on Electrochemical Properties of Weld Joint of N80 HFWWelded Pipe

The corrosion resistance of N80 HFW welded pipe is an important parameter which affects its service life.The electrochemical properties of the weld joint of the N80 HFW welded pipe under the weld condition and after heat treatment are studied by means of the microelectrode scanning method and the electrochemical self-corrosion potential method.The results show that, compared to the as-welded N80 HFW pipe, the N80 HFW pipe as-heat treated has such advantageous electrochemical properties as more uniform distribution of current density, smaller potential difference, and better microstructure homogeneity both in the weld zone and base metal zone;and the sensitivity coefficient of grooving corrosion is reduced from 1.32 under the weld condition to 1.21 after heat treatment so that the chances of occurrence of grooving corrosion is reduced.