Free-cutting copper alloy processed material and method for producing free-cutting copper alloy processed material

摘要

This free-cutting copper alloy has Cu: 76.0-79.0%, Si: 3.1-3.6%, Sn: 0.36-0.84%, P: 0.06-0.14 %, Pb: 0.022 to 0.10%, the balance consists of Zn and inevitable impurities, the composition satisfies the following relationship, 74.4 ≦ f1 = Cu + 0.8 × Si−8.5 × Sn + P + 0.5 × Pb ≦ 78.2, 61.2 ≦ f2 = Cu−4.4 × Si−0.7 × Sn−P + 0.5 × Pb ≦ 62.8, 0.09 ≦ f3 = P / Sn ≦ 0.35, The area ratio (%) of the constituent phases satisfies the following relationship: 30 ≦ κ ≦ 65, 0 ≦ γ ≦ 2.0, 0 ≦ β ≦ 0.3, 0 ≦ μ ≦ 2.0, 96.5 ≦ f4 = α + κ, 99.4 ≦ f5 = α + κ + γ + μ, 0 ≦ f6 = γ + μ ≦ 3.0, 36 ≦ f7 = 1.05 × κ + 6 × γ ^1/2 + 0.5 × μ ≦ 72, The α phase has a κ phase, the long side of the γ phase is 50 μm or less, and the long side of the μ phase is 25 μm or less.