Fe-Ni-Cr系合金426の酸化の研究

抄録

This study was made to elucidate the oxidation behavior of the alloy 426 of Fe-Ni-Cr system.
The oxide layers of the alloy 426 were made by using three different methods, i.e. the wet hydrogen firing, the air baking and the air baking following the wet hydrogen firing.
Our microscopic observation and X-ray analysis tell us:
(1) That the firing temperature, the firing time and the moisture of hydrogen are most effective to the rate of weight gain of the oxide layer during the wet hydrogen firing.
(2) That the oxidation behavior of the specimens which are rolled and washed by acid follow the parabolic law, whereas the specimens which are rolled but are not given acid washing deviate from the parabolic law.
(3) That the fact that the rate of oxidation have something to do with the history of the works of the alloy, may be explained by the selective oxidation of grain boundary which is assured by the microscopic observation.
(4) That the weight gain of the specimens which are given the air baking following the firing by wet hydrogen do not show a parabolic oxidation.
(5) That the activation energy 28.5kcal/mol is obtained from our experimental results based upon the oxidation gain during the air baking.
(6) It appears from our X-ray analysis that the main reaction products are Cr₂O₃ in the wet hydrogen firing and are (Cr, Fe)₂O₃ in the air baking.