OXIDATION OF HASTELLOY C276

摘要

Oxidation of Hastelloy C276 was studied at 300-800℃ in atmospheres that ranged from 0.01 to 100% O_2. X-ray diffraction and scanning electron microscopy indicated formation of Cr_2O_3 scales. The oxidation kinetics were approximately parabolic, but, contrary to expectations, there was no clear trend of scale-growth kinetics vs. oxygen partial pressure. This anomalous response was attributed to an extrinsic effect from cation doping of the scale, with a possible contribution from the rough, as-rolled surface finish of most of the coupons that were tested. The scales that formed on polished surfaces at 500℃ were smooth and nanocrystalline; those that formed at 800℃ were dense and consisted of faceted grains with an average size of ≈0.5-1蘭.