| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrathin steel sheet which reduces the damage to a surface coating film when being worked, without deteriorating the rigidity of a worked article of it. SOLUTION: The steel comprises, by mass, 0.0800% or less C, 0.0600% or less N, 2.0% or less Si, 2.0% or less Mn, 0.10% or less P, 0.05% or less S, 2.0% or less Al and the balance substantially Fe. The method for manufacturing the steel sheet comprises; cold-rolling the steel having the above composition; and recrystallization-annealing it or further heat-treating it while adjusting the atmosphere, the temperature and the period of time, so as to control the change in an amount of N in the steel, and particularly, regulating the amount of N and the hardness in the surface layer and the central layer into an adequate range. Thus obtained ultrathin steel sheet causes little damage to the surface coating film when deformation-worked, and shows superior panel rigidity. COPYRIGHT: (C)2006,JPO&NCIPI
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