| Aluminum alloy has widely and large used in many fields,because of its high performance,long using life and easily recoverability,thus the produced benefits of secondary aluminum industry is very large.But in China,the proportion of recycled aluminum in total aluminum consumption is still small.The waste of the aluminum alloy mainly in casting process,the riser and shrinkage will lose about 8% of the amount of castings.And the metal lose is about 20% in machining process of aluminum ingot subsequently.Thus the factual utilization rate of aluminum alloy is less than 52%.Because the recovery rate aluminum Alloy liquid is only about 40%,and there are a series of problems by melting recovery,including serious loss ratio,high energy consumption and high pollution to environment.In contrast,the use of new technology for scrap recycling is more directly transform waste into extrusion products,and does not involve melting process.ADC12 aluminum alloy chips were considered in this paper,the chips of ADC12 aluminum alloy were obtained by cutting process.And the billet was prepared by CSP process.The compactness of billet affects the quality of extrusion parts directly.Therefore,the compactness of billet and CSP process parameters were studied by hydrostatic apparatus and Taguchi method.Taguchi method controls the quality of the product and focuses on the effective application of engineering strategies.This method can avoid the influence of uncontrolled environmental factors,and minimize the variation by less number of experiments,while minimum output characteristic fluctuations.The main influence factors of error fluctuations can becontrolled to improve the stability of output characteristics of the products by considering the influence of the parameters fluctuation on the output characteristics.Taguchi method focuses on a signal-to-noise(S/N)ratio instead of porosity simulation results to evaluate characteristic in the optimum setting analysis.There are three types of quality characteristics including lower the better,nominal the best and higher the better.Namely the signal-to-noise ratio is a simple assessment of quality indicator when evaluating changes in process parameters that affect the performance of product.Generally,better signal is obtained when the noise is small,so the maximum S/N corresponding the best results.In this paper density ratio is studied as the mass characteristic and the lower the better can be used.The optimal combination has been obtained by Taguchi method,which means that a compacting temperature of 250?,a compacting pressure of 640 MPa and the holding time of 47 s can be used to achieve quality ADC12 alloy billets produced by CSR process.This paper also studied the pretreatment and solid state recycling process of dirty ADC12 Aluminum Alloy chips pollution by emulsion.The microstructure of extrusion parts were observed and analyzed by optical microstructure analysis,scanning electron microscopy,transmission electron microscopy and EDS analysis.The tensile strength of extrusion parts prepared by clean ADC12 chips is 256 MPa,and its elongation is 9.27%.The tensile strength of extrusion parts prepared by preheated dirty ADC12 chip at 350 ? is 305 MPa,and the elongation is about11.85%.Comprehensive mechanical properties are the best of all extrusion parts.The evaporation of emulsion caused carbon residue remains on the chip surface by preheating,and the carbon residue would be involved in the recycling parts with oxide during the extrusion process,and dispersed into the matrix uniformly.So the strengthening mechanism of extrusion parts prepared by preheated dirty ADC12 chip at 350? is mainly fine grain strengthening and dispersion strengthening. |
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