| Title |
Strain Behavior during High Temperature Oxidation of Fe-20Cr-5Al-xLa Alloy Thin Strip |
| Authors |
김강오(Kang O Kim) ; 이기선(Kee Sun Lee) ; 오규환(Kyu Hwan Oh) ; 박원욱(Won Wook Park) ; 라형용(Hyung Yong Ra) |
| Abstract |
Fe-20Cr-5Al(-0.06La) alloy thin strip was spontaneously strained by growth stress which was developed during isothermal high temperature oxidation. The activation energy, Q, for high temperature strain(creep) was determined from the relation between oxidation temperature and stain rate. In La free alloy, the activation energy was calculated to about 332.6 kJ/㏖. The compressive stress of about 651.9 ㎫ and tensile stress of about 10.1 ㎫ was developed in α-alumina oxide film and metal substrate respectively. The high growth stress was relaxed through the not only creep of metal substrate but also local detachment of α-alumina oxide film from the metal substrate. In La added alloy, the activation energy was calculated to about 263.6 kJ/㏖. which was seriously lower than the activation energy for La free alloy. In this case, α-alumina oxide film was not spalled or fractured. The addition of La contributed to not only the decrease of growth stress but also the stress relaxation through creep. It was concluded that easy stress relaxation process was crucial to enhance the adherence between α-alumina film and metal substrate. |