Microstructure And Texture Evolution Of AZ31 Magnesium Alloy During Compression-Torsion Deformation

AZ31 magnesium alloy is the most commonly used commercial deformation at present,which has great development potential.Plastic forming,especially severe plastic deformation,can significantly improve the properties of magnesium alloys,which is a current research hotspot.Under different stress states,the deformation mechanism and strengthening and toughening mechanism of magnesium alloy are quite different.Significant progress has been made in the research on simple stress state.However,there are few reports on the study of the complex stress state of compression-torsion loading.The study of microstructure evolution and deformation mechanism of alloy under complex stress state is the theoretical basis of multi-directional loading deformation.In this paper,AZ31 wrought magnesium alloy is taken as the research object.The comparative experiments of different deformation parameters and different initial grain sizes are carried out on Gleeble3500 thermal simulator.Different grain sizes are controlled by annealing treatment.At the same time,the microstructure and properties of the alloy after deformation are characterized by optical microscope,scanning electron microscope with energy spectrum analysis function and microhardness tester.The microstructure evolution and deformation mechanism of compression-torsion deformation under different conditions are analyzed,which can provide theoretical basis for rotary extrusion forming AZ31 alloy under similar deformation stress.The main research contents are as follows:(1)By changing the deformation parameters(deformation temperature,strain rate)of AZ31 alloy under compression-torsion deformation,the change rule of rheological curve of magnesium alloy under different conditions,the change of microstructure(grain refinement,dynamic recrystallization ratio and microstructure texture)and properties(microhardness)were investigated,and the recrystallization mechanism of magnesium alloy under compression-torsion combined deformation was analyzed.(2)Taking the extruded AZ31 magnesium alloy as the research object,combined with annealing treatment,the grain size,recrystallization ratio and texture evolution of magnesium alloy with different initial grain sizes under compression-torsion deformation were investigated.The influence of initial grain size on the degree of twinning and texture evolution was investigated,and the microstructure and properties control method combining preheating treatment and compression-torsion deformation was proposed.(3)Taking the extruded AZ31 magnesium alloy as the research object,combined with annealing treatment,the grain size,recrystallization ratio and texture evolution of magnesium alloy with different initial grain sizes under compression-torsion deformation were investigated.The influence of initial grain size on the degree of twinning and texture evolution was investigated,and the microstructure and properties control method combining preheating treatment and compression-torsion deformation was proposed.