Simulative And Experimental Study On The Extrusion Process Of Magnesium Alloys

Magnesium alloy is a new developing light structural material in the automotive and electronics industries, which has the advantage of low intensity, good electric conduction and transmits heat, high specific strength and stiffness, excellent machinability, and so no. The method of the finite element analyze is an important method on the researching engineering. Applying the ripe finite element analyze method to the extrusion process, can analyze and study conveniently the characteristic of hot metal deformation, and are helpful to guide the technology of Magnesium alloys extrusion.The deformation characteristics of the hot extrusion process of AZ91 magnesium alloy strips are analyzed by the combination of 3D FEM simulation and experimentally verification in the first part. The result shows that the evolution of the extrusion load and exit temperature in the whole stages can be revealed factually by using 3D FEM simulation, with the high agreement of the numerical simulation and real extrusion test. The surface quality, microstructure and mechanical properties of the extrudate are determined on the highest temperature and tensile stress at the die exit, improved as the decrease of the temperature at the die exit according to the present investigation.In the second part, the isothermal extrusion process of AZ31 magnesium alloy was studied by using FEM simulation with experimental validation. The constant outlet temperature of 455℃was obtained by controlling the ram speed. The distribution of stress and strain is steady throughout the whole cycle of extrusion process, thus ensuring the homogeneity of the product. It was found that the tendency of extrusion load can be predicted within the permit precision. Further, the distribution and variation regularity of mold maximum temperature, stress, strain deformation in the process was predicted to study the law of AZ31 magnesium alloy flow and develop the actual extrusion process. By the comparison of the extrusion with constant ram speed, the constant outlet temperature was obtained in the process of isothermal extrusion with better production efficiency, which suggested the uniform mechanical properties along the length direction, the accurate dimension, and better efficiency.Through the experiment, the validity and dependability of the Extrusion's simulation has been verified in the thesis, and has drew the conclusion that the simulation is very important function for researching and popularizing the magnesium alloy structure parts, it can shorten time, reduce costs for the research and development of products of magnesium alloy in simulation experiment, the craft parameter of the simulation experiment, can be the real application, or the practical application offers the reference of real value.