Study on accelerated corrosion behavior and mechanism of X80 pipeline steel welded joint under cyclic salt spray test

The corrosion behavior of X80 pipeline steel double-sided submerged arc welded joints in marine atmospheric environment was simulated by cyclic salt spray accelerated corrosion test. The corrosion behavior and mechanism of X80 pipeline steel welded joints were studied by means of SEM, XRD and electrochemical test, and the current effect of welded joints was evaluated by means of macroscopic and microscopic morphology, corrosion weight loss, corrosion product composition, polarization curve and impedance spectrum of samples with different cycles. The results show that with the extension of corrosion time, the corrosion morphology of each region of the welded joint changes from the initial uniform corrosion to a large difference. During the whole process, the surface fluctuation of the base-metal area is small, and no obvious pitting pits are observed. Cracks are gradually generated in the heat affected zone and the weld metal, and as the cracks expand, the surface pits deepen. The corrosion rate of the three regions of the welded joint showed a trend of rapid increase-slow decrease-slow increase-slow decrease. It provides conditions for further research on the simulation and correlation of accelerated corrosion test.