Research On Extrusion Forming Process Of Large And Complex Rare Earth Magnesium Alloy Box Components

With the continuous development of the industrial age,rare earth magnesium alloys have become the first choice for lightweight equipment components.For large-size（one-side length over 600 mm and large projected area）box-type components are mostly formed by casting,but there are many product defects.The internal structure of the product obtained by plastic forming is denser,and the structure and mechanical properties are better.At present,there are few related researches on the extrusion of large-size boxes of rare-earth magnesium alloys.In this paper,Mg-13Gd-4Y-2Zn-0.5Zr rare earth magnesium alloy is used as the research material,and the cup forming experiment is used for auxiliary verification.On the basis of forming the box,the box forming process scheme is optimized.Structural design mold,and finally carry out physical experiment verification.The main conclusions are as follows:（1）By analyzing the structural characteristics and forming difficulties of the box,the calculated forming load of the box far exceeds the rated load of the laboratory extruder,and the local loading test plan is determined;（2）The single-pass and isothermal multi-pass cup forming tests are used to determine the box forming scheme for auxiliary verification.The results show that when the cup-shaped part is formed in a single pass（scheme A）,the lamellar and bulk LPSO phases of the finally obtained metal material are relatively more and uniformly distributed,and the white Mg5（Gd,Y,Zn）phase is relatively uniform.Distributed in the α-Mg matrix,the average grain size is small（14.12μm）.Compared with scheme B,scheme A avoids the endothermic growth of grains caused by more forming passes and multiple heating,and room temperature Under the phenomenon of poor comprehensive mechanical properties.Therefore,for complex box forming experiments,the number of box forming passes and heating times should be reduced as much as possible;（3）According to the forming load and structural characteristics of the box,with local loading as the central idea,two forming schemes I and Ⅱ are formulated,and the finite element simulation software Deform-3D is used to simulate the forming of the box.The results show that scheme Ⅱ adopts the method of local loading and dislocation forming,which not only greatly improves the material utilization rate,but also makes the flow velocity of the metal billet more uniform during the forming process of the box body,resulting in the equivalent stress on the cavity wall of the box body,Factors such as strain are better than scheme I;（4）Optimize the shape of the pre-formed blank of Scheme Ⅱ,and add a 20 mm thick boss behind the pre-formed blank to avoid the phenomenon that the wall of the elongated cavity is too low during the forming process;（5）According to the unique structure of the box,combined with the central idea of local loading,a mold for box forming was designed;after that,the box forming physical experiment was carried out,and the prepared box results showed that the box forming height,metal filling conditions and so on meet the requirements.