Development Of Automobile Engine Cover Made Of Magnesium Alloy

Currently,automobile engine cover is mostly made of aluminum alloy, iron and steel, engineering plastics and so on. Magnesium alloy, as the lightest engineering metal material, has good casting proerty, mechanical process property, high damping propety and shield property as well. With the rapid development of automobile industry and the increasing demand for automotive products with light weight, more safety, reduced energy consumption, reduced noise and pollution. Magnesium alloy has become an ideal material to replace aluminum alloy, iron and steel and engineering plastics.This paper is based on the study of developping a kind of automobile engine cover made of Magnesium alloy which take the place of the traditional steel plate pressing parts in order to reduce the noise and weight of engine.The study consisted of the following aspects: the structural design of automobile engine cover made of Magnesium alloy and the design of die-casting die; the design and optimization of die-casting process; the analysis and testing of cover formation and properties. During the course of this study, Two kinds of Magnesium alloy materials(AM50 and AZ91D) be seleted respectively and utilized gas SF6 and N2(purified) as protectors in the melting process and then carried on die-casting experiement with a Switzerland EVOLUTION 53D cold chamber Magnesium alloy die-casting machine and finally,dealt with the surface treatment of castings by means of microarc oxidation method and spraying plastics technique. The finding has shown that, after T6 heat treatment, this kind of engine cover made of Magnesium alloy has higher mechanical properties which meet totally the requirements of property standands. For instance, Tensile strenghth attain 245Mpa; Brinell handness attain 70; Extension rate is up to 8 percent; Modulus of elasticity is 42Gpa. Besides, the optimal casting process parameters obtained are as follows: the temerature of heated die is 240℃;the heating pipe is 250℃;the cooling pipe is 25℃,the pouring temperature is 670℃; the speed of head injection is 6m/s. After the process of die-casting, the cover came into form perfectly and is in good quality both inside and outside.In the study, AZ91D Magnesium alloy be used in this engine cover of the trial production and put it into practices, it to be proved, the automobitive engine equipped with Magnesium alloy cover is able to work soundly and the noise is obviously cut down and achieve the expected goal.