Influence of CrN surface compound on the initial stages of high temperature oxidation of ferritic stainless steel

Segregation phenomena and formation of surface compounds on Fe–17Cr (ferritic stainless steel) were studied at temperatures up to 800 °C upon annealing and kinetically controlled oxidation by photoelectron spectroscopy and inelastic electron background analysis. The results revealed the formation of a chromium nitride surface compound during annealing in ultrahigh vacuum at temperatures exceeding 527 °C. Surface enrichment of P, As, and other trace elements became more prominent at higher temperatures approaching 800 °C. It was found that nitrogen was buried below the surface oxide layer during oxygen exposure, yet it had little effect on the rate of oxidation. However, the formation of CrN surface compound promoted the selective oxidation of Cr initially, which is of great importance in processing and application environments involving high temperature and controlled atmosphere conditions.