Research On Die Casting Technology Of Magnesium Alloys

Magnesium alloys, as a structural material family, have many advantages, such as high specific strength, high specific rigidity, good casting capability and easy to recycle. In its mass application in automobile and motorcycles, it is able to reduce the weight and vibration, to lower the noise and oil consumption, and to increase kinetic performance of the vehicles. Currently, Mg alloys are widely used in many manufacturing industries.In the present research, in spite of the lack of the experience and facilities of Magnesium alloys die casting in Chongqing, on the basis of mature Al die casting technology and the difference of physics and chemistry properties between Mg alloys and Al alloys, the difficult issues of Mg alloys die casting production technique system consisting of the protective melting of Magnesium alloys, pouring, die casting, moulding, surface treatment have been studied with available research instrumentation, production equipments.Based upon the requirements on the properties and functions of salt flux, a new protective flux consisting of 20-40 wt.% of MgCl2, 30-50 wt. % of KCI, 5-15 wt % of BaCl2 2-10 wt. % of CaF2 has been developed. For gas protection, the relationship between concentration of SF6 and effective protection of molten Mg alloys has been determined.To determine the optimized processing parameters, Mg alloy parts of more than ten for motorcycle have been cast. The difference between die casting of Mg alloys and die casting of Al alloys is systematically researched and the principles guiding die casting parameter control were put forward. With the optimized casting parameters, the tensile strength of the die castings was above 200MPa, the elongation is above 3%.Based upon an analysis of current surface treatment techniques for Mg alloys, a feasible technique for the surface treatment of motorbike Mg castings was put forward. In addition, micro arc oxidizing Mg alloys was experimental studied.