| 摘要 |
PURPOSE:To prevent generation of scattering in permiation by using an extremely low carbon Al killed cold rolling steel plate having a length of 300mm in the rolling direction of the segregated area and a thickness of 0.3mm. CONSTITUTION:An extremely low carbon Al killed cold rolling steel plate having a length of 300mm or less in the rolling direction of the segregated area and a thickness of 0.3mm or less is used. Segregation is caused mainly as meltable element in steel is solidified while being condensed at the final solidifying part upon casting and, while being varied thereafter in its shape through heat treatment and the like, it is elongated in the rolling direction by the rolling work, resulting in a segregation area. Consequently, when it is worked to the plate thickness of a shadow mask, the thickness of the segregation area becomes smaller relatively if it is shorter in length, thus inferior permeation does not occur by only controlling the length within 300mm.
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