Effects Of Asymmetric Rolling And Heat Treatment On Mechanical Properties Of Al-12.7Si-0.7Mg Aluminium Alloy

Asymmetric rolling has been introduced to the hot-extruded Al-12.7Si-0.7Mg alloy to provide an abundant deformation characteristic microstructure. On this basis, the solution and aging process of this alloy has been further studied to improve its mechanical properties. As a result,6×××wrought aluminum alloy can be partially replaced by Al-Si alloy. The goals of saving aluminum resources with reducing consumption and emissions can be achieved.In the present study, the orthogonal experiment method was used firstly for selecting the most significant factors affecting the mechanical properties of Al-12.7Si-0.7Mg alloy from solution time, aging temperature, aging time and reduction of rolling. Then, the alloy was rolled before solution, after solution and aging treatment respectively, the optimum model which can simultaneously improve the strength and plasticity was obtained by comparing the results. Finally, the mechanical properties of the aluminium alloy Al-12.7Si-0.7Mg were investigated under different aging process with the same reduction and solution treatment. Mechanical properties including strength, elongation and micro-hardness under different process have been thoroughly compared by tensile test and micro-hardness test. Micro-structural changes have also been analyzed through the application of metallurgical observation and tensile fracture scanning. The following results have been obtained:(1) Direct-vision analysis method was used to compare the results of orthogonal test. It gives that aging temperature is the most significant among the selected four factors. In addition, the best mechanical properties were obtained when the aging temperature was180℃with the same reduction.(2) By comparing different models of rolling and heat treatment, it was more effective to improve mechanical properties of the alloy. In addition, asymmetric rolling has been proved to be a superior model to symmetric rolling.(3) The most significant effect of improving mechanical properties was appeared with the reduction of50%amone different reduction models.(4) Elongation and strength of extruded alloy Al-12.7Si-0.7Mg which was asymmetric rolled with the reduction of48.2%, and followed by solution treatment of540℃×90min and aging of180℃×2.5h can reach10.87%and373MPa, respectively. Obviously, this process has improved the elongation strength simultaneously compared with the mechanical properties of the specimen without rolling.