Development of low-cost weathering steel for photovoltaic supports

The demand for galvanized steels used for the photovoltaic supports has been increasing significantly with the widely application of photovoltaic equipment. However, the producing progress of galvanized steel has caused serious environment pollution which mainly includes water pollution and soil pollution. Therefore, the alternatives of galvanized steel are sought by numerous steel manufactures. Weathering steel emerged as one of its substitutes. In this paper, three types of weathering steel were developed as substitutes for galvanized steel Q235. The mechanical properties and wet-dry accelerated tests were carried out for the steel. The surface morphology, composition and element distribution of the corrosion products were analyzed in detail. Additionally, the weight loss and corrosion rate of the weathering steel after service of 20 and 30 years were predicted according to the results of current work and the testing data of National Environmental Corrosion Platform for Material. The results show that all the weathering steels could fulfill the required grade of the mechanical properties. Compared with Q235, the corrosion rate of Type 2 is the most suitable in the three types of weathering steels for photovoltaic supports and decreases by 30.3% after 20 years and by 31.0% after 30 years while the steel costs less pricey alloys.