Researches On Extrusion Deformation Process And Properties Of AZ31Magnesium Alloy Special Profile

In virtue of the small density, high specific strength, of excellent performance ofreducing noise and vibration properties and resistance to electromagnetic interferencecharacteristics, Magnesium alloy could promote realization the lightweight of the autoand train, reducing traction power of train, and cutting down vibration and noise. Themagnesium alloy parts have been used as the train seat and the framework on thehigh-speed rail system in Germany and France, and magnesium alloy is used as thelightweight material all over the world. The main application of magnesium alloyprofiles with its diameter size above400mm is in high-speed rail and light rail car citystructure, luggage rack, floor and wall and so on. It will further expand the applicationof magnesium alloy in the train after the successful development. Due to the lack ofmagnesium metal resources of most western industrialized countries, the automobileapplication of magnesium alloy profiles is still in the initial stage. The large sizemagnesium alloy profiles processing technology did not have big breakthrough, whichgreatly limits the development of magnesium alloy parts industry, and providesdevelopment space for our country the leading the world in these fields.In this paper, a special hollow profile was explored. To save time and cost, theDEFORM-3D finite element simulation method was used to analyze the effective stressand strain. It discovered the irrational distribution of wall thickness of profile will causeextrusion defects, and structure optimization and simulation were made. The resultssuggested the revise of profile and molds were correct. In the subsequent study，AZ31magnesium alloy was extruded. The result suggested defects existed in both profilestructure and extrusion mold, which might cause twisting and filling defect. After theoptimization of the profile structure and dies, the hollow special magnesium alloyprofiles with good properties was obtained. The extrusion result is also verified thecorrectness simulation. It suggests that the DEFORM-3D finite element simulation isfeasible in complex extrusion process. The microstructure and mechanical propertiestest results show that the profiles present inhomogeneous character in organization andmechanical performance. It suggests that extrusion deformation is not absolutelyuniform in the cross section of hollow profile. In addition, in order to improve thecomprehensive mechanical properties of as-extruded magnesium alloy, two kinds ofshear process have been designed: linear channel shear process and135°-nonlinear corner shearing process. The shearing process results obtained at250℃shows that thereason linear shear process improving the tension-compression asymmetry performanceof as-extruded AZ31magnesium alloy is that the weakening of basal texture, and thereason135°-nonlinear corner shear process have effects of improving thetension-compression asymmetry performance of as-extruded AZ31magnesium alloy isthat the grains have been refined.