Shadow mask for color Braun tubes, comprises iron group alloy board containing nickel and cobalt, having predetermined crystal grain size and resistance

摘要

The low heat-expansion type shadow mask (1) has an iron group alloy board (2) containing nickel and cobalt. The iron group alloy board has 0.2% resistance of 240-320 N/mm<2>, and crystal grain size of 6-9 when measured by particle size measuring method according to JIS G0551.