Galvanic corrosion behavior of nuclear steam turbine welded joint in chloride environment

To investigate the effect of geometry of welded joint on the galvanic corrosion behavior, the macroscopic electrochemical experiments, scanning vibrating electrode technique (SVET) and immersion tests were used to study the galvanic corrosion behavior of welded joint of 25Cr2Ni2MoV rotor steel in the chloride solution. The results indicate that the corrosion potential of the WM is the lowest and the corrosion current density is the highest. That is to say, the WM is the anodic region which is prior to be corroded while the BM and the HAZ are the cathodic region which are protected. The infinite focus microscope (IFM) and scanning electron microscope (SEM) were used to further observe the morphology of the specimen surfaces. It is found that the effect of galvanic corrosion is more significant with the increase of welded joint size, but when the joint size increases to a certain extent, the galvanic corrosion effect is weakened.