| 摘要 |
PROBLEM TO BE SOLVED: To improve the machinability of a copper alloy without the incorporation of Pb by allowing it to have a specified compsn. contg. Cu, Si, and the balance Zn. SOLUTION: This alloy contains, by weight, 69 to 79% Cu, 2.0 to 4.0% Si and the balance Zn. In the case the quantity of Si to be added is <2.0%, the formation ofγphases sufficient for securing industrially satisfiable machinability can not be executed. On the other hand, in the case the quantity of Si to be added exceeds 4.0%, further machinability improving effect is not shown. By the addition of Si, fluidity at the time of casting, strength, wear resistance, stress corrosion cracking resistance and high temp. oxidation resistance are improved as well as machinability. The alloy is preferably incorporated with at least one among 0.02 to 0.4% Bi 0.02 to 0.4% Te and 0.02 to 0.4% Se as well. In this way, even in the case a complicated shape is subjected to machining at a high speed, machinability of a high degree can be exhibited.
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