Patent ID: 11421301

Abstract:
This free-cutting copper alloy casting contains: 76.0-79.0% Cu, 3.1-3.6% Si, 0.36-0.85% Sn, 0.06-0.14% P, 0.022-0.10% Pb, with the remainder being made up of Zn and unavoidable impurities. This composition satisfies the following relations: 75.5≤f1=Cu+0.8×Si−7.5×Sn+P+0.5×Pb≤78.7, 60.8≤f2=Cu−4.5×Si—0.8×Sn−P+0.5×Pb≤62.2, 0.09≤f3=P/Sn≤0.35. The area ratios (%) of the constituent phases satisfy the following relations, 30≤κ≤63, 0≤γ≤2.0, 0≤β≤0.3, 0≤μ≤2.0, 96.5≤f4=α+κ, 99.3≤f5=α+κ+γ+ρ, 0≤f6=γ+μ≤3.0, and 37≤f7=1.05×κ+6×γ1/2+0.5×μ≤72. The κ phase is present within the α phase, the long side of the γ phase does not exceed 50 μm, and the long side of the μ phase does not exceed 25 μm.