| 摘要 |
PROBLEM TO BE SOLVED: To prevent the abnormality of the shape of pores and linear defects generated at the time of etching piercing by controlling the total number or grain size of oxide inclusions contained in an alloy sheet obtd. by casting and rolling or the amt. and grain size of oxide based inclusions to specified value. SOLUTION: The total number of oxide based inclusions contained in an Fe-Ni alloy sheet is controlled to <=1×107 pieces per (g) of sample, and also, the number of oxide based inclusions of >=5μm grain size is controlled to <=1×105 per (g), preferably to <=1×103. Moreover, preferably, the total piece of oxide based inclusions contained in the Fe-Ni alloy sheet is controlled to about <=50 ppm by weight ratio, and also, the amt. or oxide based inclusions of >=5μm is controlled to about <=20 ppm. The grain size, number and amt. of the oxide based inclusions can be obtd. by melting a sample, extracting only oxide based inclusions and measuring the grain size distribution of the extracts by a light diffraction scattering method or a centrifugal precipitation- light transmission method.
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