Ion microprobe study of the scale formed during high temperature oxidation of high silicon EN-1.4301 stainless steel

Abstract A study of the oxide layer formed on the surface of high silicon (0.8%) EN-1.4301 (AISI-304) stainless steel after 125 h oxidation in air at 1273 K has been performed by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), RBS and proton microprobe. Oxidation experiments in synthetic air were performed in a thermobalance and the kinetic curve is compared to that of a standard EN-1.4301 austenitic stainless steel. These results show that the high silicon steel presents an enhanced oxidation resistance. XRD experiments show that the only crystalline species present in the scale is Cr 2 O 3 . Nevertheless, transversal section studies of the scale using proton microprobe show the development of a multilayered scale formed by an amorphous silicon rich layer in the scale to alloy interface and a Cr 2 O 3 oxide layer in the external scale. Those results are confirmed by SEM experiments. The formation of the silica layer can be the responsible of the increase in the resistance to high temperature oxidation in this steel.