The oxidation of a precipitation-hardening (PH) steels is a rather unexplored area. In this study an attempt is made to estimate
the oxidation mechanism and the kinetics that take place up to 850 °C. For this purpose specimens of the material under examination
were isothermally heated at 725, 775, 800, 825, and 850 °C for 12 h in O2 atmosphere. The as-treated samples were examined with SEM and XRD, while kinetics were based on thermogravimetric (TG) results.
From this examination it was deduced that the oxidation of this steel is accomplished at minimum three steps, following the
changes of the scale morphology and the kinetics. After 850 °C although that the oxidation rate increases, the scale morphology
does not change. From the calculations of the rate constant kp and the activation energy for the phenomena below 850 °C, it was deduced that the oxidation phenomena during this stage provides
another barrier to the deterioration of the ferrous material.