Influence of Holding time on the corrosion behavior of Hot Rolled Strip in Beijing natural environment

摘要

By using electrochemical workstation, scanning electron microscope (SEM) with outdoor exposure experiment in Beijing natural environment, the corrosion resistance of hot rolled sheet coiled at 590°C for different holding time was studied. The eutectoid reaction in the process of heat preservation can reduce the number of pores and cracks in the oxide layer and increase the density of the oxide layer. At the same time, the Fe_3O_4 phase with great corrosion resistance can be formed. The contents of Fe_3O_4 phase in the oxidation layer of hot rolled sheet coils needs to be controlled at a certain level, too low is not conducive to the improvement of corrosion resistance while too high tend to aggravate the cracking risk of oxide layer and reduce the corrosion resistance because of the properties of hard and brittle phase. Combined with the results of indoor and outdoor experiments, the corrosion resistance of the samples was the best with 40 min heat preservation after coiling. The properties of the original oxide scale can be improved by heat treatment. The research work in this paper can provide the data support for the adjustment the field production process of hot rolling products to get the higher corrosion property products.