Strengthened Alpha Brass and Method for Manufacturing the Same

Abstract

An object of the present invention is to provide a strengthened alpha brass having a good balance between high offset yield strength and formability without deteriorated stress relaxation resistance in comparison with conventional brass and a manufacturing method of the strengthened alpha brass. In order to achieve this object, a strengthened alpha brass having a composition of 63 wt % to 75 wt % copper, incidental impurities and the balance zinc; the strengthened alpha brass which is obtained by using a starting plate material subjected to a re-crystallization annealing to have a grain size from 1-micron meter to 2-micron meter followed by cold rolling in 5% to 40% reduction, then the plate material is low temperature annealed at a temperature equal to or higher than the temperature at which a 0.2% offset yield strength exhibits a maximum value to adjust the 0.2% offset yield strength ([Sigma]0.2: MPa) to be equal to or higher than 90% of its maximum value is adopted. The strengthened alpha brass has a 0.2% offset yield strength of 450 MPa to 750 MPa and [minimum bend radius (MBR)]/[plate thickness (t)] and [0.2% offset yield strength] satisfy the following formula MBR/t≦0.0125×σ0.2−6.7 (σ0.2: 0.2% offset yield strength) , and [Erichsen value (Er: mm)] and [0.2% offset yield strength] preferably satisfy the following formula. Er≧−0.011×σ0.2+13.7 (σ0.2: 0.2% offset yield strength)

Dependencies are inferred from the claim text.