Strength and corrosion behavior of Fe-25Cr alloys under various strain rates in Ar and N2-0.1%SO2 at 973 K

The mechanical strength and corrosion behavior of Fe–25Cr alloys were studied in Ar and in N2–0.1SO2 at 973 K under strain rates of 2.7 × 10−4–10−6/s. A 0.1μm thick adhering Cr2O3 layer is formed on the alloy by pre-treatment in Ar. Scales formed in N2–0.1SO2 are thicker with poorer adherence to the metal substrate. The tensile strength is higher, about 9–19 MPa, in Ar than in N2–0.1SO2. However, the strain-rate sensitivities show similar values in both environments. Deformation is concentrated near the grain boundaries of the alloy, and it is more conspicuous at lower strain rates. Scale growth is rapidly increased by the deformation in N2–0.1SO2, and the scale growth rate increases with the increase in strain rates. The scale growth rate is higher at higher strain rates and the scale increases in sulfides.