Comparative Study On The Semisolid Forming Process Between Cast Aluminum Alloy And Wrought Aluminum Alloy

The main task of this research is to probe in to the semisolid forming of cast aluminum ZL109 and wrought aluminum 7050. The process of the raw billet casting, billet remelting, component forging and heat treatment were investigated and described in this article. The structure of the billets, the structure during the remelting process and components and the mechanical properties were also researched.In the first step, billets were made with the method of low super heat casting. A suitable billet making process has been made. With the experiment, the suitable casting temperatures of these two alloys were as follows. ZL109 alloy should be cast with the temperature of 566-568℃, while 7050 alloy should be cast with the temperature of 621-623℃. It was proved by experiment that, the eutectic structure was refined and the a phase was increased for ZL109 alloy, while as the latter, the a phase was refined. So it can refine casting structure by using the low super heat casting method to make billet.The billets were remelted by the high frequency inducing machine. The suitable thixoforming temperature was received by cut experiment. At last, the suitable semisolid temperature for ZL109 alloy was 569±1℃, while for 7050 alloy was 610± 1℃. The suitable heat process for the former was: 8 ℃-1200 A, 450℃-1000A, 520℃-600A, 550℃-423A, 569℃-0A, for the latter was: 8℃-1200A, 520℃-1000A, 550℃-600A, 590℃-423A,610℃-0A. The structure of the billet during the course of remelting was researched. The eutectic structure of ZL109 alloy was refined during the remelting process and the bacilliform structure was disappeared at last, while theastructure of 7050 alloy was rounded during the remelting process.A forging mould was designed and manufactured to forge the tensile specimen. The mould was tested using plumbum billet to make decision of the suitable billet dimension. The mould was heated by electric heating slices around it, as this style of heating having a heating effect. And the suitable temperature of the mould was 250℃. The billets were forged by the hydraulic pressure machine, and the pressure was 150t. Three samples in the middle of five cavities for forged component were full filled.The components were heat treated. The process of heat treatment was as follows: as for ZL109 alloy, having a solution treatment of 3 hours at 473℃, having a ageing treatment of 7 hours at 210℃, while for 7050 alloy, having a solution treatment of 3 hours at 473℃, having a ageing treatment of 5 hours at 120℃ and 15 hours at 174℃. Then the components mechanical...