PURPOSE: To obtain stable press-formability, by a method wherein the generation of elongation at yield point due to aging is completely controlled by specifying the atmosphere of annealing by using very low carbon aluminium killed steel sheet as material in the manufacturing method by a preannealing process.
CONSTITUTION: Very low carbon aluminum killed steel sheet is cold finish rolled and the thickness of product is made 0.2mm or less. This steel is annealed at 600W750°C in an atmosphere composed of 100ppm (by volume) or less CO+CO2, 0.5% (by volume) or more H2 and the remainder N2 and H2O in continuous annealing process. Then, after tempera rolling of it, the shadow mask for color television Braun tube is obtained through etching boring process and press forming process. By this method, the elongation at yield point is not generated, the occurrence of elongation at yield point according to the progress of aging at burning treatment in photoe-etching process being very few and stable press- formability can be obtained.
USUKI SATORU
ENDOU SHIYOUJI
MIYAMOTO OSAMU
| JPS5553844A | 1980-04-19 | |||
| JPS58181825A | 1983-10-24 |