A Comparison of the High-Temperature Oxidation of 17Cr-2Ni and 18Cr-8Ni Austenitic Stainless Steels at 973 K

The oxidation behavior in air at 973 K of theaustenitic stainless steels 18Cr8Ni and17Cr-2.5Ni-10.5Mn-2Cu-0.17N (low-nickel content), wasstudied in a thermobalance. The steels were heated fromroom temperature up to 973K at 10 K min-1, oxidizedfor 80 hr and then cooled to room temperature at 80 Kmin-1. The two steels had the same weightgains, 0.18 mg cm-2, which is equivalent tooxidation layers about 1.15 μm theoretical thickness. In both cases, thegeneral shapes of the ΔWS-1 (mgcm-2) curves vs. t (hours) were parabolic,but X-ray diffraction of the oxidized surfaces, surfaceand crosssection optical microscopy and SEM observations and EDSmicroanalysis show important differences betweenthem.