| 摘要 |
PURPOSE:To prevent deformation of a magnetic shield member from occuring during step and to reduce the magnetic annealing of the member in small scale by forming it of iron magnetic allow containing special amount of nickel and with hardness of higher than special value in annealed state after forging it. CONSTITUTION:This member is made of material of iron magnetic alloy containing 70 to 90 by weight of nickel in percent and has a Vickers hardness of higher than 140 in the annealed state after forging it. For example, a shield case for the tape recorder head is formed with magnetic alloy containing 80% of nicket, 4% of molybdenum and residue of iron, and is then annealed in small scale at 900 deg.C for 5 minutes with 160 of Vickers heardness. Thus, it can simplify the step by lowering the magnetic annealing condition to low temperature for short time still to improve the hardness and mechanical strength thereof to thereby prevent deformation of the member from occurring in production and at carrying time to thus improve the maneuverability thereof. |
