Fracture Mechanism of LY12 Cast Aluminum in Substation under Alternating Load

The main cause and failure process of the fracture of the cast aluminum fittings for the down lead of a 750 kV substation in the wind region of Xinjiang were identified through numerical simulation, electrochemical tests, and microscopic characterization.The results indicated that the reaction force caused by the horizontal static wind load at the endpoint of the down lead was greater than the design value, and the tensile force and bending moment acting on the endpoint of the down lead were not considered in design. The on-site sample exhibited crack+pitting corrosion characteristics, and the polarization curve represented the activation corrosion process, which was consistent with the results obtained in the laboratory under the action of load and alternating current, and was the result of the synergistic effect of mechanics and electrochemistry.