The martensitic stainless steel AISI 440C was boronized at a temperature of 950 °C for about 4 hr. Heat treatments at a temperature of 850 °C for about 2-8 hr were performed to eliminate the FeB phase of the boride layer. The oxidation investigations were carried out at a given temperature of 900 °C on different surface conditions. It was found that the FeB phase was completely dissolved and transformed to the Fe2B phase after a heat treatment at a temperature of 850 °C for about 8 hr. The oxidation behavior of the non-boronized, boronized and boronized with heat treatment of 8 hr conditions exhibit a parabolic manner, while the specimens boronized with heat treatments of 2 – 6 hr show a linear manner. The single-phase (Fe2B) boride layer on the martensitic stainless steel AISI 440C possesses a lowest oxidation rate as compared to other investigated surface conditions.
