Laser Heat Treatment Effects on Corrosion of Grade X80 Welded Pipeline Joints

The surfaces of welded joints on Grade X80 pipeline steel were processed with a carbon dioxide (CO2) laser, and the effects of this laser heat treatment (LHT) on electrochemical corrosion in a solution saturated with hydrogen sulfide (H2S) were analyzed with electrochemical corrosion tests. The microstructures and residual stresses of the joints were analyzed before and after LHT. The surface corrosion morphologies and chemical components of corrosion products before and after LHT were observed. The results show that the self-corrosion potentials of the welded joints increased from –670 to –600 mV; and the corrosion morphologies changed from total corrosion to local corrosion, with improved corrosion resistance.