| 摘要 |
PROBLEM TO BE SOLVED: To securely remove oil stuck to the surface of foil and to obtain the structure of a high cubic body orientating ratio by heating an Al foil in a reducing atmosphere contg. oxygen of specified concn. and an inert gas and executing final annealing prior to the surface roughening treatment of the Al foil. SOLUTION: The Al foil of 99.9% purity and about 0.1 mm thickness is heated in a reducing atmosphere contg. 1 to 100 ppm oxygen, 0 to 10% inert gas, and the balance substantial reducing gas and is subjected to final annealing. The holding heating temp. in the final annealing is held to 530 to 620 deg.C. The holding time is desirably controlled to 2 to 10 hr. Moreover, as the reducing gas, hydrogen can be cited. The reducing atmosphere is preferably held even in a cooling stage after the holding stage in the final annealing. In the cooling stage, desirably, the cooling rate is controlled in such a manner that it is not made too fast by furnate cooling or the like, and, concretely, the cooling is executed, derirably, at the cooling rate of <=100 deg.C/hr on the average.
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