Effect of La and Ce on the corrosion behaviour of steel rebar HRB400E with mill scale in chloride environments

The effect of rare earth elements La and Ce on the corrosion behaviour of steel rebar HRB400E with mill scale was investigated in detail using electrochemical measurements and numerous characterization techniques after salt spray testing with NaCl. The results indicated that addition of La and Ce could decrease the corrosion rates of HRB400RE by more than 50 %. At the initial stages of corrosion, corrosion products on HRB400ERE were observed only on the exterior of the mill scale, with a relatively high percentage of magnetite and hematite. On the contrary, corrosion products were present on both the exterior and interior of the mill scale on HRB400ERE. During the corrosion process, the protective index of the rust on HRB400ERE was consistently higher than that on HRB400E. The dense and protective mill scale and rust layers formed on HRB400ERE both contributed to the enhanced corrosion resistance of the RE-alloyed steel.