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Jiang J.,Harbin Institute of Technology | Wang Y.,Harbin Institute of Technology | Chen G.,Harbin Institute of Technology | Liu J.,Harbin Institute of Technology | And 2 more authors.
Materials and Design | Year: 2012

A double control forming technology of motorcycle wheel was firstly developed to form the complex parts with high mechanical properties. The mechanical properties and microstructure of the AZ91D magnesium alloy motorcycle wheels formed by double control forming and die casting was compared. The results of numerical simulation showed that the velocity magnitude in wheel rib was small than that in other positions. The pressure and temperature decreased from the wheel hub to the overflow launders. Large surface defect concentration indicated the oxides and entrapments existed mainly in the well-designed overflow launders. The experimental results confirmed that the motorcycle wheel's complex shape can be achieved by the high-speed filling in the injection procedure and the mechanical properties of the parts were greatly improved due to the forging pressure. It is clear from the micrographs that the high pressure caused by forging system results in obvious grain refinement of the primary α-Mg and uniform distribution of the eutectic consisting of the eutectic α-Mg and β-Mg17Al12. Higher mechanical properties including ultimate tensile strength of 246MPa, elongation of 9.5% and Vicker-hardness of 87.9 were obtained in the parts formed by double control forming due to the fine and uniform microstructure without defects in comparison to die casting. © 2012 Elsevier Ltd. Source


Jiang J.,Harbin Institute of Technology | Cheng Y.,Harbin Institute of Technology | Du Z.,Harbin Institute of Technology | Liu J.,Harbin Institute of Technology | And 2 more authors.
Journal of Materials Science and Technology | Year: 2013

A set of novel forming die combining the advantages of dies casting and forging was designed, by which double control forming idea was firstly proposed. The motorcycle wheel made of AM60B alloy was used as the typical component to demonstrate advantages of the double control forming. The effect of pressure on the mechanical properties and microstructure of the parts formed by double control forming was investigated. The results showed that high mechanical properties and complex shape were achieved in the parts formed by double control forming. Compared to die casting, the mechanical properties of the formed part significantly increased and the microstructure changed from the coarse dendrites to fine equiaxed grains. The shrinkage voids and microcracks in the formed parts were obviously reduced or even completely eliminated with the increase of pressure. When a pressure of 4000 kN was applied, the optimal mechanical properties such as ultimate tensile strength of 265.6 MPa and elongation of 21% were achieved and the microstructure was characterized by fine and uniform equiaxed grains due to the large undercooling degree caused by the high pressure. © 2013, The editorial office of Journal of Materials Science & Technology. Source


Jiang J.,Harbin Institute of Technology | Wang Y.,Harbin Institute of Technology | Li Y.,Mg Technology Shen Zhen Co. of Ka Shui Group | Shan W.,Mg Technology Shen Zhen Co. of Ka Shui Group | Luo S.,Harbin Institute of Technology
Materials and Design | Year: 2012

Double control forming technology was firstly proposed for meeting the producing requirements of complex Mg alloy parts with high mechanical properties. Not only the high-speed filling but also high-pressure densifying and refining could be achieved in double control forming technology. A typical part of motorcycle cylinder body was used for demonstrating its advantages. The results showed that complete filling could be achieved by injection system of double control forming device and the microstructure of formed part was densified and refined well by its forging system. High mechanical properties such as ultimate tensile strength of 241. MPa and elongation of 13.9% were achieved in the parts formed by double control forming. Compared to die casting, the ultimate tensile strength was increased by 63.9% and elongation was increased by 3.3 times. A large number of fine equiaxed grains with the average size less than 20 μm were found in the microstructure of parts formed by double control forming. A refined microstructure also led to a more uniform distribution of primary equiaxed grains and second phase. Casting defects such as shrinkage voids were removed from the microstructure due to the forging pressure. © 2012 Elsevier Ltd. Source


Jiang J.,Harbin Institute of Technology | Wang Y.,Harbin Institute of Technology | Li Y.,Mg Technology Shen Zhen Co. of Ka Shui Group | Qu J.,Harbin Institute of Technology | And 2 more authors.
Journal of Materials Processing Technology | Year: 2012

A double control forming technology combining the die casting and forging was firstly proposed for the production of Mg alloy components with enhanced properties. In this technology, high-speed filling of liquid melt and high-pressure forging of partially solidified melt were performed by using injection and forging systems of a double control forming device. Some Mg alloy motorcycle wheel components were produced by die casting and double control forming to verify the improvement of the mechanical properties of components formed by double control forming. The results showed that double control forming was an alternative technology for producing the complex Mg alloy components with enhanced properties. Average tensile strength and elongation of Mg alloy components produced by double control forming were greatly improved in comparison with die casting. The average tensile strength was enhanced from 126.8 MPa to 213 MPa and elongation was improved from 3.5% to 7.2%. The optimal process parameters were obtained according to the results of orthogonal experiments, which involved pouring temperature of 675°C, injection speed of 2 m/s and die temperature of 210°C. The improved nucleation frequency in the melt caused by the forging pressure led to successful grain refinement of the microstructure of the component produced by double control forming. The defects were removed from the microstructure due to plastic deformation caused by the forging pressure. A refined and densified microstructure led to an enhancement of mechanical properties of Mg alloy component produced by double control forming. © 2012 Elsevier B.V. Source

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