| 摘要 |
PURPOSE:To provide a titled extrudate which decreases the variance in wear resistance and improves simultaneously machineability by specifying the compsn. consisting of Si, Cu, Sn, Pb, Bi and Al. CONSTITUTION:A wear-resistant Al alloy extrudate having excellent machineability contains 12-30wt% Si, 0.3-7% Cu, contains >=1 kinds among Sn, Pb, Bi and contains further 0.3-2% Mg if necessary and consists of the balance Al and unavoidable impurities. Said extrudate is obtd. by subjecting the billet formed by melt casting of an Al alloy having the prescribed compsn. to hot rolling at about 350-420 deg.C. The primary crystal Si particles in the alloy structure of the casting ingot is broken down by the above-mentioned hot extrusion so that the primary crystal Si particles having 40-80mu grain size occupy >=60% of the total area of the primary crystal Si particles; at the same time, the needle crystals of the eutectic Si particles are also parted in the longitudinal direction so that said particles having <=10mu grain size occupy >=60% of the total area of the eutectic Si particles. The primary crystal and eutectic Si particles are further uniformly dispersed, by which the excellent performance as mentioned above is obtd.
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