Oxidation and scaling can affect a thin layer under exposed surfaces, or penetrate at significant depths, depending on environmental oxidizing conditions, duration of the exposure, and temperature. The severity of this process can go as far as the complete dislocation of the wall.

A high Si content can prevent in-depth oxidation to the detriment of impact resistance. The process can be slowed down by the addition of alloy elements such as Cr, Mo… Such alloying elements should only be considered when oxidation/scaling is the most important mechanism of degradation involved, because whereas several of these alloy elements can normally reduce oxidation/scaling effectively, they can also cause the formation of carbide, which has a negative effect on impact resistance and thermal shock resistance.