Analysis of the Microstructural Transformation and Oxidation Behavior of Fe–0.9Cr Alloy Steel at 900–1150 °C

Abstract

The oxidation behavior of Fe-0.9Cr alloy steel was investigated to understand its phase transition mechanism in the temperature range of 900-1150 °C. The main objective of this work was to study the oxidation behavior and elemental diffusion behavior of Fe-0.9Cr alloy steel during heating. It was found that when the temperature was lower than 950 °C, the oxidation weight gain curve conformed to a linear law, indicating that the interface reaction was a rate-controlling process. When the heating temperature was higher than 950 °C, the oxidation kinetics curve followed a parabolic law. Inner oxide scales formed at 1050 °C and 1150 °C were dominated by a stable FeCr 2 O 4 layer, and they were thicker than that formed at 950 °C. When the oxidation time was less than 38 min, the oxidation weight gain curve at 1100 °C almost coincided with that at 1150 °C. In the continuous oxidation process above 1050 °C, Cr 2 O 3 grew through a substitution reaction and formed a continuous solid solution which reduced the effective area of Fe 2? diffusion, thereby reducing the oxidation rate and improving the corrosion resistance.