Improvement of high-temperature initial oxidation behavior of HR3C austenitic heat-resistant steel using silicon modification: experimental and first-principle study

A novel silicon-containing austenitic stainless steel with excellent high-temperature initial oxidation resistance was prepared by adding 2.5 wt.% Si and modifying composition of the HR3C steels. Compared with HR3C steel, the oxidation resistance property of the steels containing silicon was markedly better at 800 degrees C. The high temperature oxidation mechanism of the steels containing silicon was analyzed by using scanning electron microscopy (SEM) with energy-dispersive spectrum (EDS) system, X-ray diffraction (XRD), glow discharge optical emission spectroscopy (GDOES), and first-principles calculations. The results show that the Si atom in the 22Cr-25Ni-2.5Si steel initially diffused from the matrix to the surface and then reacted with O-2 to form SiO2. The SiO2 had an inhibiting effect on the diffusion of Cr from matrix resulting in maintenance of the stability of the oxidation film and improvement of the oxidation resistance as compared with the HR3C.