| 摘要 |
PURPOSE:To improve the mechanical workability such as the wear resistance of a tool, shaving treatability, etc., and hot workability of the titled alloy by incorporating >=2 kinds among Mn, Zr and Cr and >=2 kinds among Pb, Sn and Bi into an Al-Zn-Cu-Mg alloy having specific compsn. CONSTITUTION:The compsn. of the high strength aluminum free cutting alloy contg., by weight, (a) 5.0-8.0% Zn, 1.5-3.0% Mg and 1.4-3.0% Cu, furthermore contg. >=2 kinds among (b) 0.05-0.3% Cr, 0.05-0.5% Mn and 0.03-0.3% Zr, contg. >=2 kinds among (c) 0.2-1.0% Pb, 0.2-1.0% Sn and 0.2-1.0% Bi and consisting of the balance Al with impurities is formed. The elements in the b group develop the fiber structure at the time of hot working to improve the strength and toughness of the alloy, and form fine crystallites to improve the hot moldability thereof. The elements in the c group improve the cuttability into pieces and reduce the wear ratio of a cutting tool, by which the service life of the tool is improved.
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