The Microstructure And Mechanical Properties Of Die Casting AM50Magnesium Alloy

AM50magnesium alloy with high strength and light weight has arousedwidespread concern and research. However, complex preparation process ofmagnesium alloy, as well as the uncertainty of various process parameters in theprocess of preparation, to a large extent restricts the application and promotion ofmagnesium alloy.Based on system research on the die casting process of magnesium alloy, thispaper further improved the preparation process of die casting, and successfullyprepared magnesium alloy rod like specimens. In order to further research theproperties, the tensile mechanical test and the metallographic analysis were performedon the magnesium alloy specimen. Besides, tensile fracture was analyzed with thescanning electron microscope(SEM). The microstructure and basic mechanicalproperties of AM50magnesium alloy were obtained. We discussed the fundamentalreason of different mechanical properties between the same batch of magnesium alloy.Magnesium alloy components of automobile seat frame structure weresuccessfully prepared based on improving the gate and casting cavity in die castingprocess. The tensile mechanical test, metallographic analysis and tensile fractureanalysis were performed on different locations of automobile frame. Moreover, weresearched the reason of different mechanical properties between different positions.The main research results were as follows:(1)66die casting AM50magnesium alloy rod like specimens were successfullyprepared and evaluated by mechanical properties test. The yield strength and tensilestrength of80%samples were found to be relatively close to123.64MPa and221.84MPa respectively.20%specimens appeared large fluctuation. The tensilestrength and fracture strain of the worst performance specimen were156.12MPa and6.29%. The tensile strength and fracture strain of the best performance specimenwere249.79MPa and.13.92%.(2) The SEM photograph of tensile fracture and metallograph showed that thesize, number and distribution of the porosity inside the specimens caused three kindsof different performance found in the same batch of specimens. Larger, more, and more nonuniform distributed porosities, which reduced the strength, provided achannel for expansion of crack inside material and greatly reduced deformationcapacity, were found in poor performance samples. While smaller, less, and moreuniform distributed porosities, which were difficult to provide a channel for expansionof crack inside material and advantageous to increase the ability of plasticdeformation, were found in good performance samples who had significantly highstrength and fracture strain.(3) Die casting AM50magnesium alloy was mainly composed of α-Mg solidsolution in matrix form and small part of Mg17Al12compound distributed indiscontinuous. The distribution, number and size of hard phase Mg17Al12significantlyinfluenced the performance of AM50magnesium alloy.(4) The mechanical properties of different positions at the same structure hadsignificant differences, although the die casting process of magnesium alloy had beenimproved. The mechanical properties of the sitting basin front part were best: thetensile strength of242.MPa, yield strength of123.65MPa, elongation of11.39%. Themechanical properties of the backrest frame were better: the tensile strength of225.85MPa, yield strength of134.51MPa.(5) Further metallographic photos and SEM photos analysis showed that thesize and distribution of porosities were the main reason of unsteady performance ofeach part in this large body structure.