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用金属型铸造铝合金铸件的工艺其经济效益甚大;铸出的铸件不但表面光洁,尺寸精度较高,内在质量好,而且劳动强度低,生产效率高,值得大力推广。现简单介绍几点实践经验与同行商榷,不妥之处,敬请批评指正。一、金属型铸造的工艺特点 1.冷却速度大,铸件组织致密。对Al—Si合金薄壁壳体铸件的组织,可与经变质的砂型铸件相媲美,经机加工后的铸件表面上,基本上无针孔缺陷。这是因冷速大,在熔炼时已溶解于铝合金液中的气体(主要是氢气),当铸件凝固时,气体来不及析出而固溶于铝合金中之故。
The metal cast aluminum alloy casting process has great economic benefits; casting castings not only surface smooth, high dimensional accuracy, good intrinsic quality, low labor intensity, high production efficiency, it is worth to promote. Now a brief introduction of a few practical experience and colleagues to discuss, inappropriate, please criticize correction. First, the characteristics of metal casting process 1 cooling speed, dense castings. Al-Si alloy thin-walled shell castings can be compared with the metamorphic sand castings, machined castings on the surface, basically no pinhole defects. This is due to large cooling speed, the gas (mainly hydrogen) dissolved in the aluminum alloy liquid during smelting, when the casting solidifies, the gas is too late to precipitate and dissolve in the aluminum alloy.