PURPOSE: To produce an Fe-Ni alloy thin sheet for a color picture tube excellent in blackening treatability, in an Fe-Ni alloy strip having a sheet thickness equal to that of a flat mask for producing a shadow mask, by prescribing the contents of Ni and Sn and the surface roughness.
CONSTITUTION: In an Fe-Ni alloy strip having a compsn. contg., by weight, 30 to 45% Ni, and in which the content of Sn as impurities is regulated to ≤0.10% and having a sheet thickness substantially equal to that of a flat mask or an aperture grill used for producing a shadow mask, its surface roughness is prescribed in such a manner that the center line average roughness (Ra) is regulated to 0.3 to 0.9μm, the average distance (Sm) of the ruggedness of a cross-sectional curve to 40 to 240μm, skewness (RsK) which is the bias index in the height direction of a roughness curve to -50 to +1.3 and the center line valley depth (Rv) of the roughness curve to 0.7 to 3.0μm. Thus, the alloy thin sheet for a color picture tube excellent in blacking treatability and capable of forming a blackened film in a short time can be obtd.
TSURU KIYOSHI
YAMAUCHI KATSUHISA
YAMADA MAKOTO
WAKASA HIROSHI
