| 摘要 |
PROBLEM TO BE SOLVED: To provide a copper alloy-made hot-die forged synchronizer ring which has high fatigue strength, particularly does not develop the breakage in a chamber part mostly and easily developing the fatigue breakage, even in the case of practically using under condition of high loading in the thinning state and displays the excellent performance for long term. SOLUTION: The hot-die forged synchronizer ring is constituted of the copper alloy having a composition by mass% of 28-34% Zn, 1.5-4% Al, 2-4.5% Mn, 0.5-2% Si, 0.05-0.5% Cr, 0.2-0.6% Ni, 0.02-0.5% Fe and the balance Cu with unavoidable impurities and the structure uniformly dispersing the relatively coarse crystallized grains and the superfine precipitations constituted with respective intermetallic compounds in the matrix ofβ-phase shown in a Cu-Zn system phase diagram and further, dispersedly distributingα-phase as acicular shape shown in the same phase diagram.
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