Effect of Grain Size on Atmospheric Corrosion Resistance of Bridge Weathering Steels

Three kinds of bridge weathering steels with different grain sizes and the same chemical composition wereprepared by different rolling and heat treatment processes.The relationship between grain size and atmosphericcorrosion resistance of these steels was investigated by corrosion potential test,simulated wet-dry alternatedaccelerated corrosion test,micro-analysis of rust cross section and XRD analysis of the corrosion products.Theresults show that the corrosion potential of the sample with the thinnest grain size was the highest.The corrosion rateand thickness reduction were the lowest and the rust layer was more compact for the bridge steel with the thinnestgrain size after simulated wet-dry alternated accelerated corrosion test.The composition of the inner rust layer formedon weathering steels with different grain sizes was the same,indicating that the structure and compactness of theinner rust layer have very important influence on the corrosion process.