Abstract
When the iron and steel are heated in the oxidizing atmosphere at high temperature, the oxidation scale penetrates into matrix right below the surface scale. The authers studied on the phenomena of this penetration under various conditions using a rimmed steel (C 0.08%).
Heating conditions: temperature 1150°C-1350°C, atmosphere O2 5-50% N2 Bal. CO2 5-50% N2 Bal. time 30mn-2h
In order to compare the individual results each other, the depth of penetration and the size of penetrated scale were measured and those results were as follows:
1) The granular scales penetrated in considerable depths even in the atmoshere of only N2 gas, and this penetration depth was nearly the same value gained when it was mixed with gases of O2 or CO2
2) Penetration of scale was greatly affected by the heating temperature: the higher the temperature, the deeper the depth and the larger the size of the penetrated scales.
3) Heated above 1300°C, huge scale appears and was remarkable under such conditions as O2 gas was added. Therefore it was evidenced that the penetration of scale took part in the defect of the over-heating.
4) The color of granular penetrated scales were light-bluish-gray and that of the huge scales were composed by both light-and dark-bluish-gray.
5) If the heating condition changed, then the thickness of surface scales increased, and huge penetrating scale was produced even at below 1300°C.
