Study On Dynamic Deformation And Corrosion Behavior Of AZ31 Magnesium Alloy With Bimodal Texture Components

With the rapid development of science and technology,people’s demand for material life is increasing day by day,and traditional metal materials are rapidly consumed.At the same time,the rapid development of the automobile industry has brought about an increase in carbon emissions,making lightweight a top priority.Due to its low density and high specific strength,Mg has been widely paid attention in recent years,and there is abundant supply of Mg in the Earth’s crust.As a result,Mg is a strategic target in our country.As the lightest structural metal material,magnesium alloy is often in service under dynamic loads.Studying the dynamic deformation behavior of magnesium alloy is beneficial to guide the service of magnesium alloy under complex loads.Considering the poor corrosion resistance of magnesium alloy,it is of great significance to improve the corrosion resistance of magnesium alloy in service by texture regulation.Therefore,taking AZ31 magnesium alloy as the research object,this paper intends to use the process combining pre-deformation and heat treatment to modify the texture distribution in magnesium alloy,and use advanced mechanics,microstructure characterization and test and analysis methods to systematically study the dynamic deformation mechanism and corrosion behavior of bimodal textured magnesium alloy,specifically as follows:(1)The bimodal textured AZ31 magnesium alloy with different texture components(<0002>//ED and<0002>⊥ ED)was prepared by pre-stretching the extruded AZ31 bar with 7%along ED and compression with different deformation amounts along ED,and then annealing treatment with different time.The dynamic compression and quasi-static compression deformation behavior and the micro mechanism affecting the mechanical behavior were studied.The results showed that the yield strength and compressive strength of magnesium alloy under dynamic compression are lower than those under quasi-static compression with the same texture characteristics.With the increase of<0002>//ED texture components,the yield strength and compressive strength gradually increased.Compared with quasi-static deformation,the extension twinning has higher activity at high strain rate.The amount of twin was closely related to the texture distribution,and more twin variants were activated at high strain rate.(2)The dynamic deformation behavior and Hall-Petch effect of multi-grain size basal textured magnesium alloys with preset dislocation were systematically studied.Two different strain rates were used in the study:1×10-3s-1 and 3×10-2s-1.The results showed that a large number of dislocation walls were formed in the tissue after the introduction of preset dislocations.These dislocation walls can inhibit the slips during subsequent tensile process and greatly improve the mechanical properties.Higher strain rates can inhibit the initiation of prismatic slip,so the yield and tensile strength of the material are improved at higher strain rates.The slope k value of H-P relationship under different states changes significantly.At high strain rate,the slope k value decreases,and the slope k value increases after preset dislocation.Higher strain rates can inhibit the initiation of prismatic slip,but soften the grain boundary barrier effect,and the dislocation wall generated after prepositioning enhances the boundary barrier effect.(3)The influence of texture distribution on corrosion properties of magnesium alloy was systematically studied.The bimodal textured AZ31 magnesium alloy with different texture components was immersed in 3%NaCl solution to test its corrosion properties.The corrosion morphology,corrosion products,corrosion structure EBSD and other data were analyzed.The results showed that the final corrosion product of AZ31 magnesium alloy in 3%NaCl solution was Mg(OH)2,and MgO as the intermediate product gradually changed to Mg(OH)2 with the prolongation of corrosion time.Different crystal plane corrosion rate is different,the corrosion resistance of the basal plane is the best,the corrosion resistance of the prismatic plane is poor.Due to the large difference in corrosion potential between the prismatic and the basal plane,galvanic corrosion units will be formed when the corrosion surface contains both the prismatic and the basal plane,which will aggravate the corrosion of materials.When the ratio of<0002>//ED texture components and<0002>⊥ED texture components are 15.2%and 74.7%,respectively,the corrosion resistance can be improved effectively.