| 摘要 |
PURPOSE:To obtain a blank material for a shadow mask having excellent press formability and magnetic characteristics by subjecting a hot-rolled steel sheet to primary cold rolling, coil annealing and secondary cold rolling then further to high dew point annealing and tertiary cold rolling. CONSTITUTION:A hot-rolled steel sheet such as aluminum-killed steel which is a raw material for a shadow mask is subjected primary cold rolling, open coil decarburization annealing and secondary cold rolling to form a steel strip having about 0.1-0.6mm. thickness. The rolling mill lubricant, etc. sticking to the strip in the stage of secondary cooling are removed by electrical cleaning, etc. and the strip is subjected to high dew point annealing at about 560-700 deg.C by box annealing, etc. and further to tertiary cold rolling at a draft of about 10- 30%. The high dew point annealing is accomplished preferably in an atmosphere of gaseous mixture of N2 and H2 and the dew point is kept at about 0-25 deg.C. The blank material for the shadow mask which has excellent magnetic characteristics and is free from a color deviation phenomena in a product, i.e. color cathode ray tube, is obtd. by the above-mentioned. |
