DECARBURIZED ANNEALING METHOD FOR STEEL SHEET FOR SHADOW MASK

摘要

PURPOSE:To prevent the development of ageing deterioration by carburizing steel sheet after decarburizing, in annealing thin steel sheet for shadow mask in color television under wet gas atmosphere by specific condition, then cooling under dry gas atmosphere at the time of decarburized-annealing. CONSTITUTION:At the time of decarburized-annealing by open-coil annealing in the process of production of the cold rolled thin steel sheet for shadow mask, firstly, the decarburized-annealing is executed under 650-750 deg.C wet gas atmosphere, having =30 deg.C dew point by containing vapor, to decarburize to =0.75ppm of C content in the steel sheet. Next, at the time of cooling, the above dew point is maintained until drop of coil temp. to 55 deg.C and the sheet is cooled under dry atmosphere of =50% H2, =1,500ppm CO, =50ppm CH4, and the thin steel sheet for shadow mask is prevented from ageing deterioration caused by carburizing from atmosphere.