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AssigneeToyo Kohan Co., Ltd.
InventorsTsuneyuki Ide, Hironao Okayama, Hiroaki Ikenaga, Susumu Shigemasa, Yasuo Tahara, Taizo Sato, Akira Ikeda
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An invar alloy steel sheet for shadow masks is provided which has improved etchability, an economical production method, a shadow mask made of the invar alloy steel sheet, and a color picture tube which incorporates the shadow mask. The invar alloy steel sheet is produced by hot working an alloy slab consisting of 33 top 40 wt % nickel with the balance being iron, and then subjecting the slab to a primary cold rolling at a rolling reduction ratio of not more than 80%, annealing at a temperature of at least 550° C., and subjecting the slab to a secondary cold rolling at a rolling reduction ratio of not more than 50%. The invar alloy steel sheet has a percentage of {100} texture of 60 to 80%.
A method for producing an invar alloy steel sheet material for a shadow mask, consisting of the steps of hot working an invar alloy slab consisting essentially of 33 to 40 wt % Ni and the balance being Fe, said invar alloy steel sheet having a percentage of {100} texture of 60 to 80% in a rolled surface thereof, subjecting the hot rolled invar alloy slab to a primary cold rolling at a rolling reduction ratio of 50 to 80%, annealing same at a temperature of 650 to 950° C., and subjecting same to a secondary cold rolling at a rolling reduction ratio of 0.05 to 40%.
Dependencies are inferred from the claim text.