Research On The Effect Of Process Factors On LFC Aluminum Alloy Casting Quality

Aluminum alloy is a kind of light alloy, it has characteristics of low density, high specific strength, good electrical conductivity, moderate price and so on. Al-Si series aluminum alloy has excellent properties such as good fluidity, low hot tearing tendency, small solidification shrinkage and so on. After modification and heat treatment, the mechanical properties, physical performance and machining performance of the machine are greatly improved, therefore, it is widely used in automotive, aerospace and other fields. LFC is a new type of green casting method, it has the advantages of simple design, high energy efficiency and environmental protection, and can be used for casting thin-walled parts with complex structure. LFC is suitable for producing automobile production and other related industries core parts, such as engine block, engine cylinder head, intake manifold aluminum alloy castings.Because some quality problems of LFC of aluminum alloy can not be solved, especially the pinhole, porosity and microstructure are poor, which seriously affect the mechanical properties of castings, and hinder the development of LFC of aluminum alloy. In this paper, in view of lost foam aluminum alloy casting hole defects, poor mechanical properties and microstructure, mainly to study the effect of process factors on the porosity, mechanical properties(hardness, tensile strength) and microstructure of aluminum alloy casting. The results of study show that:Firstly, the effects of three kinds of process factors(pouring temperature, vacuum degree and pattern density) on the porosity and mechanical properties(hardness and tensile strength) of the lost foam casting aluminum alloy castings are studied by the orthogonal experiment, and observe the microstructure and tensile fracture morphology, the optimum process parameters are obtained by range analysis, and research on the relationship of porosity and mechanical properties. The results show that when the pouring temperature is 760?, the pattern density is 16Kg/m3, the negative pressure is 0.02 MPa, the porosity of castings is the smallest, and various performance is the best. Meanwhile the effects of three kinds of process factors(pouring temperature, vacuum degree and pattern density) on the porosity and density of LFC aluminum alloy castings are studied by single factor experiment, and obtain the law of the change of porosity and density with three kinds of single factor.Secondly, using the optimal process parameters have been the base foundry casting, experiments qualified castings and casting porosity, density, microstructure and mechanical properties are relatively good.Finally, analysize and summarize the other process factors(including refining treatment, coatings, gating system, modification and refinement processing and sand) effects on the porosity or pore defects(pinholes and air holes) LFC aluminum alloy castings, and put forward the solution to improve the densification of aluminum alloy castings.