Study on Performance Degradation of Galvanized Steel Used for Transmission Tower under Typical Atmospheric Environment

According to the testing of galvanized steel used for transmission tower serving in mountainous areas and serious corrosive industrial corrosive areas, the degradation of galvanized layer of tower steel plate was analyzed. Microstructure of galvanized steel was observed by optical microscope (OM) and scanning electron microscope (SEM), and the thickness of galvanized layer was measured. Results show that the corrosion resistance of galvanized steel gradually decreased when they have been operated for 15 years at serious industrial corrosive conditions. The corrosion test of carbon steel used for transmission tower was carried out by neutral salt spray corrosion chamber for 50 days, and the mechanical properties of carbon steel were tested by microcomputer controlled universal testing machine. Based on the experiment data, we found the mechanical properties of galvanized steels obviously weakened after 50 days of neutral salt spray accelerated corrosion testing. Especially, the decrease of elongation was reaching by 31%. Finite element calculation of transmission tower was carried out based on the remaining corrosion parameters. Calculation results showed that the bearing capacity of the transmission tower significantly decreased, so that it could not met the requirements of safe operation of the transmission line.