Study On Organization And Mechanical Properties For High Strength And Toughness Of Sc-bearing Al-Si Alloys

Cast aluminum alloy has many advantages, such as low prices、organization isotropic、can get a special organization、easy to produce parts of complex shaped.can be small batchand mass production, and because of its high specific strength、good casting properties andcorrosion resistance, widely used in machinery、automotive、aerospace and other fields, Al-Sialloy is mainly used in the manufacture of piston、cylinder、cylinder head and crankcasecastings. With the automobile industry improve the product lightweight and hight-intensiverequirements, improve the mechanical properties of Al-Si alloy has become an urgent problemto be solvsd.In this paper, casting aluminum-silicon alloy based on 702A (Si：6%-8%，Cu：1.2%-1.8%，Mg：0.25%-0.5%，Mn：0.1%-0.2%，Ti：0.05%-0.15%，Sr：0.01%-0.06%),study on strength and toughness of the material. By using the orthogonal experimental methodand poor get the best mechanical properties in the case, determined the optimum ratio ofalloying elements: Si（6.5%），Cu（1.5%），Mg（0.25%），Mn（0.1%），Ti（0.15%），Sr（0.06%），Fe（≤0.03%）. By adding the micro-alloying elements Sc, while the meltingprocess of the alloy studied,determine the alloy melt refinement, modification,refinedprocessing technology on organizational performance.This paper also studied the impact of the different contents of Sc cast 702A Al-Si alloyperformance, and further study of the different heat treatment parameters containing Sc702A Al-Si alloy. The results show that:after T6 heat treatment, did not add any Sc 702Atensile strength of Al-Si alloyσb=360MPa，δ=5.7%; when the Sc content in the alloy up to0.2℅, tensile strength reached the maximum of the Al-Si alloysσb=384MPa，δ=7.4%.Casting 702A Al-Si alloy high strength and toughness requirements to achieve furtherimprove, materials to improve the performance to meet a large car engine cylinder block,cylinder head needs.