| As a typical metal material with dense hexagonal(HCP)crystal structure,magnesium alloy will form a strong basal texture under conventional rolling process,which will affect the forming properties of magnesium alloy.Based on AZ31 magnesium alloy as the object,through experiment and simulation study of normal rolling(NR),cross rolling(CR),different speed rolling(DSR)and cross different speed rolling(CDSR)process on the material microstructure,texture evolution and the influence law of forming performance,the purpose is to obtain fine uniform,weak basal texture,good formability of AZ31 rolled plate and the corresponding rolling technology.The main research content and research results of this subject are as follows:(1)The microstructure of AZ31 magnesium alloy plate in the initial extrusion state was characterized,the microstructure of the initial plate was measured by EBSD,and the true stress-strain curve of the material was measured by uniaxial stretching and plane compression along the ED direction of magnesium alloy plate,and uniaxial stretching along the TD direction.The hardening parameters of single crystal slip system of magnesium alloy were obtained by using the true stress-strain curve fitting with the crystal plasticity self-consistent model.(2)The texture evolution of AZ31 magnesium alloy under NR,CR,DSR and CDSR processing conditions was simulated with a self-consistent model.The texture of the basal plane obtained by NR and DSR processes forms a symmetrical oval distribution along the TD direction,the texture of CR and CDSR presents an approximately circular uniform distribution along the RD direction and TD direction,and the texture of CDSR basal plane deviates from the ND direction,forming a distribution of 5°with the RD direction and about 10° with the TD direction.Due to the additional shear stress generated by DSR process,the c-axis of some grains deviated from the ND direction,thus weakening the texture strength of the substrate.The texture distribution of CR and CDSR was more uniform,but the texture strength was slightly higher than that of NR and DSR.(3)The hot-rolling experiments of NR,CR,DSR and CDSR on AZ31 magnesium alloy plates were carried out,and the microstructure of the rolled magnesium alloy was observed.The results showed that the dynamic recrystallization of the magnesium alloy plates under CR,DSR and CDSR processes was more complete than that under NR processes,and the grain size of the magnesium alloy plates was refined.Under CR and CDSR processes,the microstructure of magnesium alloy plate is more uniform,while under DSR processes,a small amount of thin grain microstructure appears,which weakens the microstructure uniformity.CR,DSR and CDSR processes can effectively reduce the strength of basal texture,and the most significant reduction is CDSR processes.(4)At room temperature,the mechanical properties of rolled magnesium alloy plates were tested in 0°,45° and 90° directions.The results showed that compared with NR process,CR,DSR and CDSR processes could improve the tensile strength of magnesium alloy plates.CR process and CDSR process significantly increased the plastic strain ratio of magnesium alloy,and the anisotropy of magnesium alloy plate decreased after rolling.The most significant is the CDSR process,with the anisotropy coefficient reduced to 0.03,which significantly improved the "ear making" effect of magnesium alloy formed in the drawing process.(5)Experiments compared with the results of simulation show that the simulation to get the texture types of the texture of basic consistent with the experiment,NR and DSR technology,in particular,the texture intensity CR process and CDSR show some differences,simulation results show that the is due to the simulation results,this paper ignores the influence of dynamic recrystallization,and rolling passes between oven heat preservation of annealing effect,so the simulation and experimental results have some deviation. |
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