Evaluation Of Weld Root Corrosion Characteristics Of X65qt Material

The preferential weld corrosion of X65QT pipe line steel material due to inadvertent usage of unqualified welding electrodes at site conditions and the factors influencing the corrosion resistance was examined. The resultant change in chemical composition and microstructure effects on various weld zones by LPR (LPR) and Galvanic corrosion (GC) methods under aerated condition in natural sea water was studied. Four types of commercial electrodes were used and its influence on root weld corrosion is discussed. The heat affected zone (HAZ) of all the welds resulted as more anodic than the weld and base metal. The influence of weld root hardness was found to have less significant for the electrodes used. The elements like Cr, Ni shows increased corrosion resistance. Mo in combination with Cr results in higher level of cathodic effect. Ni content is outperforming than Cr+Mo on corrosion resistance. Si equally contributes corrosion resistance compared to Ni. The type of metallurgical grain shows significant effect on corrosion characteristics.