Effect Of Multi-directional Forging On Microstructure And Properties Of Magnesium Alloy

In recent years,magnesium and its alloys have potential applications as the lightest structural materials to reduce the weight and further improve the fuel efficiencies.However,due to the low symmetry hexagonal close packed crystal structures and limited number of slip systems at room temperature,strong basal texture usually forms after rolling or extrusion process,which leads to the poor ductility and formability at room temperature.And this severely hinders their wide spread application.Looking for a simple,efficient and reliable method,to improve the formability and mechanical properties of magnesium and its alloys is a topic of general concern.Generly,in order to improve the formability and mechanical properties of the magnesium alloy,the alloy is processed by alloying or special processing method is used to refine the grain and weaken the texture.But most of it is still in the lab,they can not achieve the industrialization of mass production,the result is not satisfied.In present work,AZ31 B,Mg-Er alloys and pure Mg pre-processed by multi-directional forging,and then the samples were elongated under different degrees at room temperature.That to study deformation characteristics and mechanical properties of different Mg alloys.Thus,some conclusions can be derived as followings:(1)After multi-directional forging,plastic property of pure Mg was imporved and the elongation could be reach 33% Texture of pure Mg was also weakened during this preprocess and lots of twinning behavior occurred.With In-Grain-Misorientation-Axes(IGMA)method qualitative discussion,we believed that non-basal slip was activated when MDFed pure Mg suffered extension at room temperature,especially pyramidal plane silp mode.(2)The enhanced mechanical properties of AZ31 alloy processed by MDF were attributed to weakening texture which made orientation of most grains favorable for twinning.Intersection of twins produced by MDF can weaken texture.The twins formed during MDF detwinned easily in the early stage of tensile deformation,which reduced the tensile yield strength.At later stage of tensile deformation,slip dominated deformation process.Recrystallization occurred in the forging process,grain was refined,and texture was weakened.(3)Mechanical properties test results showed that the Mg-2Er alloy obtained a large elongation,It's not decided by adding rare earth Er promote nonbasal slip,but more effective to improve the plasticity is weakening of texture by multi-directional forging.