Fe-Ni-Co alloy thin strip for shadow masks having high strength and low coefficient of thermal expansion, along with excellent magnetic properties

Abstract

A purpose of the present invention is to provide an Fe—Ni—Co alloy having high strength and a low coefficient of thermal expansion, along with excellent magnetic properties. The present invention provides an Fe—Ni—Co alloy thin strip for shadow masks having high strength and a low coefficient of, thermal expansion, along with excellent magnetic properties, including, on a mass basis, 30 to 35% Ni, 2 to 6% Co, 0.1 to 0.4% Nb, 0.2 to 0.5% Mn, and the rest Fe and unavoidable impurities, wherein the unavoidable impurities includes 0.005% or less C, 0.002% or less S and 0.005% or less N and the grain size before etching through said strip is 7.0 to 10.0 in terms of grain size number stipulated in JIS G 0551.

What is claimed is:  
     
         1 . A Fe—Ni—Co alloy thin strip for shadow masks having high strength and a low coefficient of thermal expansion, along with excellent magnetic properties, comprising, on a mass basis, 30 to 35% Ni, 2 to 6% Co, 0.1 to 0.4% Nb, 0.2 to 0.5% Mn, and the rest Fe and unavoidable impurities, wherein the unavoidable impurities comprises 0.005% or less C, 0.002% or less S and 0.005% or less N and the grain size before etching through said strip is 7.0 to 10.0 in terms of grain size number stipulated in JIS G 0551.  
     
     
         2 . A Fe—Ni—Co alloy thin strip for shadow masks having high strength and a low coefficient of thermal expansion, along with excellent magnetic properties, comprising, on a mass basis, 30 to 35% Ni, 2 to 6% Co, 0.1 to 0.4% Nb, 0.2 to 0.5% Mn, and the rest Fe and unavoidable impurities, wherein the unavoidable impurities comprises 0.005% or less C, 0.002% or less S and 0.005% or less N and precipitates and inclusions are 0.2 μm to 5 μm in size and the total mass of them is 0.5 μg/mm 3  to 1.5 μg/mm 3 .  
     
     
         3 . The Fe—Ni—Co alloy thin strip for shadow masks having high strength and a low coefficient of thermal expansion, along with excellent magnetic properties according to  claim 2 , wherein the grain size before etching through said strip is  7 . 0  to  10 . 0  in terms of grain size number stipulated in JIS G  0551 .  
     
     
         4 . The Fe—Ni—Co alloy thin strip for shadow masks having high strength and a low coefficient of thermal expansion, along with excellent magnetic properties according to any one of  claims 1  to  3 , further comprising 0.03 to 0.10% Si in the solid solution state.