To obtain a Cu-Zn-Sn alloy for a member in contact with water, excellent in dezincification resistance and machinability, by subjecting a Cu-Zn- Sn alloy of specified composition to heating and cooling under respectively specified temp. conditions and changing its structure.
In producing a Cu-Zn-Sn alloy having a composition consisting of 0.9-3.0% Sn, 37-45% Zn, and the balance Cu, the alloy is heat-treated at 500-550°C for 30sec and then cooled down to 350°C at ≤0.4°C/sec cooling rate. In the structure of this alloy, γ-phases of ≥3% content are precipitated at 3-20% area occupancy in the grain boundaries of α-phases having ≥0.5% Sn content and 40-97% area occupancy, or the γ-phases are precipitated in the grain boundaries of the α-phases and β-phases having ≥1.5% Sn content and 0-40% area occupancy. By this method, the Cu-Zn-Sn alloy, remarkably improved in dezincification resistance and machinability and having excellent properties required of a member in contact with water, such as water tap, can be produced.
ASHIE NOBUYUKI
NAKAMURA KATSUAKI
HAMAZAKI MASANAO
UCHIDA TORU
