High Temperature Corrosion of Al Hot-Dipped Low Carbon Steels in N2/H2S-Mixed Gases
A low carbon steel was hot-dip aluminized, and corroded in the N2/0.4%H2S-mixed gas at 650-850°C for 20-50 h in order to find the effect of aluminizing on the high-temperature corrosion of the low carbon steel in the H2S environment. A thin Al topcoat and a thick Al-Fe alloy layer that consisted primarily of Al5Fe2 and some FeAl and Al3Fe formed on the surface after aluminizing. The corrosion rate increased with an increase in temperature. Hot-dip aluminizing increased the corrosion resistance of the carbon steel through forming a thin protective α-Al2O3 scale on the surface. The α-Al2O3 scale was susceptible to spallation. During corrosion, internal voids formed in the Al-Fe alloy layer, where the Al5Fe2, AlFe, and Al3Fe compounds gradually transformed through interdiffusion.
Prof. Andreas Öchsner, Prof. Graeme E. Murch, Ali Shokuhfar and J.M.P.Q. Delgado
M. A. Abro and D. B. Lee, "High Temperature Corrosion of Al Hot-Dipped Low Carbon Steels in N2/H2S-Mixed Gases", Defect and Diffusion Forum, Vol. 369, pp. 59-64, 2016