Development of hot rolled weathering angle steel for transmission towers

Abstract

In this study, Q355 grade hot-rolled weathering angle steel (WAS) was successfully developed and produced for transmission towers (also known as electricity pylons) by chemical composition and process design. The microstructure and mechanical properties were investigated using optical microscopy, a universal material tester, and an impact tester. Cyclic immersion experiments were performed to study the corrosion behaviour of WAS and Q355 grade hot-rolled conventional angle steel (CAS) when exposed to a simulated industrial atmospheric environment. The characteristics of the rust layers on the tested samples were observed by scanning electron microscope, analysed by x-ray diffraction, and studied by polarisation measurements. The results indicated that WAS has good comprehensive mechanical properties. The weight loss showed that the corrosion resistance performance of WAS is superior to that of CAS. The components of the rust layers consisted primarily of α-FeOOH, γ-FeOOH and Fe3O4. However, the content of α-FeOOH in WAS was more than that in CAS and increased as corrosion progressed. The rust layer on WAS, comprised an α-FeOOH phase, and was more dense and adherent to the substrate than on CAS, providing better protection and lower corrosion weight loss than CAS. The electrochemical parameters show that the WAS has better corrosion resistance.