| 摘要 |
PROBLEM TO BE SOLVED: To clear the environmental problem of lead elution and to improve dezincing properties, machinability and hot forgeability in the alloy by allowing it to contain components uniformly dispersing a base phase and a low m.p. point component. SOLUTION: In this alloy, by the addition of at least one among Se, Fe and B, Bi as a low m.p. component is uniformly dispersed. As a result, its machinability including the reduction of machining resistance, the satisfiability of the surface finished condition or the evaluation of cut power can be improved. Relating to this Bi, a base phase has been fractionated, and it has the low m.p. and is melted by heat generation at the time of machining, and therefore, has lubricating effect. Moreover, since the base phase itself is made finer by Fe or B, the precipitated Bi is uniformly dispersed, and intermetallic compds. (Zn+Se and Cu+Se) are formed by Se, so that, similarly, Bi is uniformly dispersed. Thus, Bi is finely scattered among the metallic crystals, by which its machining resistance is uniformized.
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