PURPOSE: To produce a shadow mask of superior photoetching characteristics and press formability for color televisions by decarburizing and annealing an extra low carbon Al killed steel strip of an extremely small solid solutionized N amount within the specific temperature range.
CONSTITUTION: The slab of an Al killed steel contg. 0.01%>C, 0.10W1.00% Mn, 0.025%>S, 0.010W0.120% sol.Al, and 100ppm>N and having the quantitative relation of (sol.Al/N)×14/27≥1.5 is made to a steel strip of ≤0.2mm thickness by hot rolling-cold rolling-annealing-skin pass rolling. After this steel strip is pierced by photoetching, it is subjected to final annealing for 1W10min at 650W850°C temperatures in a decarburizing atmosphere to fix the solid solutionized N in the steel strip as AlN. The press formability is considerably improved and the product superior as a shadow mask for color television cathode-ray tubes is obtained.
SUDA TOYOJI
ARAKI KENJI
KURATA MASAYUKI
YAMANA HIDEO
NIPPON MINING CO
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