Effect of Alloying Elements Si, S, Cu, Sn, and Ni on Oxidation of Low Carbon Steels between 1050 and 1180°C in Air

Low carbon steels were oxidized isothermally at 1050 and 1180 degrees C for 4 hr in air in order to determine the effect of alloying elements Si, S, Cu, Sn, and Ni on oxidation. For oxidation resistance of low carbon steels, the beneficial elements were Si, Cu, and Ni, whereas the harmful elements were S and Sn. The most active alloying element, Si, was scattered inside the oxide scale, at the scale-alloy interface, and as an internal oxide precipitate. The relatively noble elements such as Cu and Ni tended to weakly segregate at the scale-alloy interface. Sulfur and Sn were weakly, uniformly distributed inside the oxide scale. Excessively thick, non-adherent scales containing interconnected pores formed at 1180 degrees C.