Galvanic corrosion of a welded joint in 3Cr low alloy pipeline steel

• Corrosion behavior of a semi-automatic gas tungsten arc welded joint in 3Cr steel was investigated in a CO2-containing environment.
• Assessment of the galvanic corrosion interactions of the different regions in the joint was carried out through microelectrochemical measurements and immersion tests.
• After immersion for 120 h, the Cr/Fe atomic ratio was in order WZ > BM > HAZ.
• For isolated BM, HAZ and WZ samples, the BM exhibited the most active OCP.
• The BM acted as an anode while the WZ acted as a cathode. The HAZ underwent little galvanic interaction.

The corrosion behavior of a semi-automatic gas tungsten arc welded joint in 3Cr steel was investigated in a CO2-containing environment. Assessment of the galvanic corrosion interactions of the different regions in the joint was carried out through microelectrochemical measurements and immersion tests. The weld zone (WZ) was determined to be the most cathodic region while the base metal (BM) was the most anodic region. The heat affected zone (HAZ) underwent little galvanic interaction, as its free potential was close to the coupled potential. The galvanic coupling effects theoretically derived from the corrosion current densities before and after coupling were in good agreement with the results of the immersion tests.