Study on Cracking of Aluminum Alloy Strain Clamps for 500kV Transmission Line

Abstract

It was found that a large number of aluminum alloy strain clamps cracked. Cracking mainly occurred in the drainage plate of strain clamps. Nondestructive testing technologies and physicochemical analysis devices such as optical microscope, spectrograph, SEM and EDS were adopted to analyze the reasons of cracking. The results tell that there are numerous shrinkage cavities and cracks inside the drainage plate of strain clamps. The maximum area fraction of shrinkage cavities is 10.7%, and the maximum size is over 1mm2. A lot of shrinkage cavities and cracks gather together to form big flaws, which seriously reduce the mechanical properties of the drainage plates. After a long period of vibration, cracks gradually develop to the surrounding cavities and connect adjacent cavities. Eventually, cracks develop to the surface of drainage plates.