NZ787155B2

NZ787155B2 - Free-cutting copper alloy and method for manufacturing free-cutting copper alloy

Info

Publication number: NZ787155B2
Application number: NZ787155A
Authority: NZ
Inventors: Hiroki Goto; Keiichiro Oishi; Kouichi SUZAKI
Original assignee: Mitsubishi Materials Corporation
Filing date: 2020-11-30
Publication date: 2025-01-28

Abstract

This free-cutting copper alloy comprises Cu: more than 59.7% but less than 64.7%, Si: more than 0.60% but less than 1.30%, Pb: more than 0.001% but less than 0.20%, Bi: more than 0.001% but less than 0.10 mass%, and P: more than 0.001% but less than 0.15%, with the remainder being Zn and unavoidable impurities, wherein the total amount of Fe, Mn, Co, and Cr is less than 0.45%, the total amount of Sn and Al is less than 0.45%, 56.7 = Cu - 4.7 × Si + 0.5 × Pb + 0.5 × Bi - 0.5 × P = 59.7 and 0.003 = Pb + Bi less than 0.25 are satisfied, 0.02 = Bi/(Pb + Bi) = 0.98 is satisfied if 0.003 = Pb + Bi less than 0.08, 0.01 = Bi/(Pb + Bi) = 0.40 or 0.85 = Bi/(Pb + Bi) = 0.98 is satisfied if 0.08 = Pb + Bi less than 0.13, 0.01 = f3 = Bi/(Pb + Bi) = 0.33 is satisfied if 0.13 = Pb + Bi less than 0.25, the metallographic structure of the alloy comprises a phase and ß phase, and 17 = ß = 75, 7.0 = (Bi + Pb - 0.001)1/2 × 10 + (P - 0.001)1/2 × 5 + (ß - 8)1/2 × (Si - 0.2)1/2 × 1.3 = 16.0 are satisfied.

Claims

1. A free-cutting copper alloy comprising: higher than 59.7 mass% and lower than 64.7 mass% of Cu; 5 higher than 0.60 mass% and lower than 1.30 mass% of Si; higher than 0.001 mass% and lower than 0.20 mass% of Pb; higher than 0.001 mass% and lower than 0.10 mass% of Bi; and higher than 0.001 mass% and lower than 0.15 mass% of P, with the balance being Zn and inevitable impurities, 10 wherein among the inevitable impurities, the total content of Fe, Mn, Co, and Cr is lower than 0.45 mass% and the total content of Sn and Al is lower than 0.45 mass%, when Cu content is represented by [Cu] mass%, Si content is represented by [Si] mass%, Pb content is represented by [Pb] mass%, Bi content is represented by [Bi] mass%, and P content is represented by [P] mass%, relationships of 15 56.7 = f1 = [Cu] - 4.7 × [Si] + 0.5 × [Pb] + 0.5 × [Bi] - 0.5 × [P] = 59.7, 0.003 = f2 = [Pb] + [Bi] < 0.25, if 0.003 = [Pb] + [Bi] < 0.08, 0.02 = f3 = [Bi]/([Pb] + [Bi]) = 0.98, if 0.08 = [Pb] + [Bi] < 0.13, 0.01 = f3 = [Bi]/([Pb] + [Bi]) = 0.40 or 0.85 = f3 = [Bi]/([Pb] + [Bi]) = 0.98, and 20 if 0.13 = [Pb] + [Bi] < 0.25, 0.01 = f3 = [Bi]/([Pb] + [Bi]) = 0.33 are satisfied, the metallographic structure comprises a phase and ß phase, and when area ratio of a phase is represented by (a)% and area ratio of ß phase is represented by (ß)%, relationships of 25 17 = f4 = (ß) = 75 and