Study On Microstructure Evolution And Mechanism Of Composite Deformation Of Magnesium Alloy

Magnesium alloy is a kind of light metal material,which belongs to the crystal structure of dense row hexagonal,and has little sliding displacement system at room temperature,resulting in low plastic deformation performance of the material at room temperature,so it restricts the wide application of magnesium alloy.The research objective of this paper is to improve the microstructure and mechanical properties of magnesium alloy materials by means of indentation and flattening composite deformation,improve the plastic forming properties of magnesium alloy materials.and expand the application field of magnesium alloy materials.The microstructure and mechanism of AZ31 magnesium alloy were studied by numerical simulation and experimental methods.The microstructure,twin structure,dynamic recrystallization volume fraction,grain size,texture strength and schmidt factor of AZ31 magnesium alloy plate were studied in this paper.The following research results are obtained:(1)The experimental study on the indentation and flattening composite deformation process of AZ31 magnesium alloy plates was carried out,and the results showed that with the increase of deformation temperature,the decrease of pressure and the decrease of tooth spacing,the grains were refined and the volume fraction of dynamic recrystallization was increased.The new dynamic recrystallized grains are easy to appear in the boundary of the original grains and form a chain structure.When the deformation temperature 300?.the reduction of 3 mm,magnesium alloy material of twin organization,most mainly appeared in the large size of the grain.(2)EBSD technique was used to measure and analyze the dynamic recrystallization volume fraction and grain size.When the deformation temperature is 350?,tooth spacing with d=8 mm,the reduction of 3 mm,after composite deformation of AZ31 magnesium alloy completely dynamic recrystallization happens,volume fraction of 94%.When the deformation temperature is 400?,reduction of 3 mm,the average grain size of 3.2 microns.(3)The texture strength of AZ31 magnesium alloy plate after composite deformation was studied,and the texture weakening mechanism was analyzed.When the deformation temperature is 400?,tooth spacing d=10 mm,reduction of 3 mm,to minimize the texture intensity,its value is 4.76.(4)After studied the deformation of composite schmidt factor variation law of AZ31 magnesium alloy sheets,when the deformation temperature is 400 C,tooth spacing d=8 mm,reduction of 2 mm,schmidt factor to achieve maximum,its value is 0.51.When the deformation temperature is 300 C,tooth spacing d?8 mm,reduction of 3 mm,schmidt factor to minimize,its value is 0.37,grain in hard orientation is not conducive to plastic deformation.