Regular Article

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

College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan Shanxi 030024, PR China

^* e-mails: jianwang1@126.com; hanpeide@126.com

Received: 27 March 2018
Accepted: 23 November 2018

Abstract

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 °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 O₂ 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.