Shadow mask for color picture tube made of iron-base material having particular grain size number

Abstract

A shadow mask for a color picture tube that is made of an iron-base alloy material containing nickel and has a low coefficient of thermal expansion. The iron-base alloy material has 0.2% proof stress of from 220 to 300 N/mm2. The grain size number measured in conformity to JIS G0551 is not more than 7.5. The degree of texture in each plane measured by X-ray diffraction method is not more than 20%. The difference between the degree of texture in each plane and that in any other plane is not more than 20%. The shadow mask is produced by press forming without undergoing annealing before the press forming.

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