Influence of alloy composition and temperature on corrosion behavior of ODS ferritic steels

The effects of alloying elements and temperature on corrosion behavior in supercritical water (SCW) were investigated for oxide dispersion strengthened (ODS) steels to design alloy compositions for corrosion-resistant ODS ferritic steels. Corrosion tests of the ODS steels were carried out at 400, 500, and 600 °C under 25 MPa with 8 ppm of dissolved oxygen. The addition of 4 wt.%Al is effective to improve the corrosion resistance of 16Cr-ODS steel, suggesting that an adequate combination between Cr and Al content ranges (14–16)Cr and (3.5–4.5)Al. The addition of Ce or Zr to W-added ODS steel is expected to increase its corrosion resistance. At higher temperatures, the addition of 4 wt.%Al to 16Cr-ODS steel induces better corrosion resistance rather than the temperature of 400 °C. It is considered that for 16Cr-ODS steels with Al, the continuous alumina mainly suppresses the inward oxygen diffusion and the Fe–Cr spinel adds to the suppression of oxygen diffusion.