Fe-ni alloy shadow mask blank with excellent etch perforation properties and method for manufacturing the same

Abstract

A shadow mask blank of Fe—Ni alloy which exhibits excellent uniformity of diameter of apertures formed by perforation with etching for the passage of electron beams, consisting of 34-38% Ni, 0.05-0.5% Mn, 4-20 ppm S, and the balance Fe and no more than specified limits of C, Si, Al, and P, with MnS inclusions 50-1,000 nm in diameter dispersed at the density of at least 1,500/mm or simply with etched holes 0.5-10 &mgr;m in diameter emerging at the density of at least 2,000/mm when the blank is immersed in a 3% nitric acid-ethyl alcohol solution at 20° C. for 30 seconds. A method of manufacturing the blank comprises hot rolling of a slab of the Fe—Ni alloy, cooling, recrystallization annealing, cold rolling, etc. under controlled conditions: e.g., hot rolling the slab at 950-1,250° C. to 2-6 mm thick, cooling the stock in the range of 900-700° C. at the rate of 0.5° C./second, continuously passing the stock through a heating furnace at 850-1,100° C. for recrystallization annealing to adjust the mean diameter of the recrystallized grains to 5-30 &mgr;m, and performing the cold rolling before the final recrystallization annealing at a reduction ratio of 50-85% and the final cold rolling at a reduction ratio of 10-40%.