| 摘要 |
PROBLEM TO BE SOLVED: To provide a hard alpha-brass material having well-balanced high-yield strength and formability, and to provide a manufacturing method therefor. SOLUTION: The alpha brass includes 62.0-71.5 wt.% copper and the balance zinc with unavoidable impurities; and has a tensile strength of 530 MPa to 620 MPa, a 0.2% yield strength (σ<SB>0.2</SB>) of 450 MPa to 540 MPa, a stress relaxation rate of 52% or less, and such an Erichsen value (Er: mm) in relation to the 0.2% yield strength (σ<SB>0.2</SB>: MPa) as to satisfy the following expression. The manufacturing method comprises the steps of: recrystallization-annealing a starting plate so that the sizes of crystal grains can be in a range between 1μm and 2μm; cold-rolling the plate at a working rate of 5% to 18%; and then low-temperature-annealing the sheet at a temperature at which the 0.2% yield strength (σ<SB>0.2</SB>) is maximized, or higher. COPYRIGHT: (C)2007,JPO&INPIT
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