IRON-NICKEL-COBALT ALLOY EXCELLENT IN ETCHING CHARACTERISTIC AND LOW THERMAL EXPANSION CHARACTERISTIC, AND SHADOW MASK EXCELLENT IN SMOOTHNESS OF INSIDE PERIPHERAL SHAPE OF ETCH PIT

摘要

PROBLEM TO BE SOLVED: To provide an alloy applicable to a shadow mask and combining etching characteristic with low thermal expansion characteristic at a low cost. SOLUTION: The alloy has a composition consisting of, by weight, >2.5 to 7% Co, 35.5 to 38% (Ni+Co), <0.1% Mn, 0.0005 to 0.004% B, and the balance essentially Fe and further has a composition consisting of, by weight, >2.5 to 7% Co, 35.5 to 38% (Ni+Co), <0.1% Mn, 0.0005 to 0.004%, in total, of (B+ Ca+Kg) (the total content of B as an essential element and either or both of Ca and Mg), and the balance essentially Fe. It is preferable to control S content to <=0.002% or C content to <0.005%.