| Magnesium alloy is the lightest metal in engineering application at present.It has the advantages of high strength,high modulus of elasticity,good heat dissipation,good shock dissipation,and so on.The ability of bearing impact load capacity is larger than aluminum alloy,and the corrosion resistance of organic and alkali is good.It has broad application prospects in the structural lightweight of aviation,aerospace,transportation,chemical industry,rocket and other fields.However,magnesium alloys have poor plasticity,poor brittleness and low strength at room temperature,which seriously restrict the application of magnesium alloys.The constrained groove pressing is a new process which is gradually developed in recent years for the preparation of large size ultra-fine grained metal sheet,which can significantly improve the comprehensive properties of the material.Therefore,it is of great theoretical and engineering significance to study the constrained groove pressing process of magnesium alloys for improving their properties and promoting the engineering application of magnesium alloys.In this paper,the influence of the CGP parameters on the microstructure,texture and mechanical properties of AZ31B magnesium alloy and its internal deformation mechanism are systematically studied through numerical simulation and experiment.The main research content of this article as follow:(1)Based on the Johnson-Cook constitutive equation,the constitutive model of AZ31B magnesium alloy is established.A finite element analysis model for the deformation process is established based on the ABAQUS software platform.The influence of press times,deformation temperature and deformation path on the grain size,the variable distribution of equal effect and the forming load of AZ31B magnesium alloy samples were studied.(2)A multi pass constrained groove pressing experiment with different deformation paths was carried out at various temperatures,and reasonable experimental conditions were determined.Metallographic analysis,X ray diffraction analysis and electron backscatter diffraction analysis were carried out on the specimens with constrained groove pressing under various technological conditions.The influence of press times,deformation temperature and deformation path on the microstructure change and deformation texture of AZ31B magnesium alloy sheet was systematically studied.The intrinsic mechanism of the influence of the constrained groove pressing process on the mechanical properties of magnesium alloy sheets is discussed.(3)The tensile strength,yield strength,elongation at post fracture,strain hardening index and plastic strain ratio of magnesium alloy specimens after deformation were studied by tensile test at room temperature and fracture morphology analysis of SEM,and the changes of comprehensive properties after the molding were analyzed. |
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