Hot Compression Deformation Behavior And Microstructure Of Wrought ZK61 Magnesium Alloy

Magnesium alloy is the lightest metal structural material for commercial use,Magnesium alloy has a very important engineering value and wide application prospect in many fields,such as transportation,communication products,aerospace and national defense because of its excellent performance.In particular,the modern electronic industry has put forward higher requirements for the thin-walled magnesium alloy.Magnesium alloys have poor plasticity at room temperature,so it is of great significance to study the forming of magnesium alloys at elevated temperatures.This paper is aimed at the problems existing in the machining process of ZK61 magnesium alloy material commonly used in electronic products,and put forword the integrated precision die forging process,then study on theoretical basis of the research,to further promote the application of magnesium alloy products in engineering.This paper selects the forged ZK61 magnesium alloy as the experimental material,simulation machine at the temperature of 323⁷23K,the strain rate of 0.001～1s^-1 under the condition of isothermal compression experiment using Gleeble-1500 D thermal evolution to analyze the rheological behavior and microstructure evolution of ZK61 magnesium alloy under different conditions.The main conclusions are as follows:（1）Because of the uneven grain structure inside the specimen,the samples showed preferred orientation and double drum shape during upsetting;Based on the analysis of thermal compression data,the rheological curves of ZK61 magnesium alloy were obtained;The influence of different height diameter ratio on the rheological behavior of the samples was determined;Finally,the thermal deformation activation energy of wrought ZK61 magnesium alloy was determined Q=1.4983×105kJ/mol,The constitutive equation of the peak flow stress of ZK61 magnesium alloy during isothermal compression plastic deformation:ε=2.59×10¹¹[sinh（0.012σ）]^5.29exp（-1.4983×10⁵/RT）（2）Based on the theory of machining graph,the experimental data of thermal compression were analyzed,and the power dissipation map,the instability map and the hot working drawing of forging ZK61 magnesium alloy were plotted by Origin software.Based on the analysis of the power dissipation coefficient and the coefficient of instability,the microstructure of the sample was analyzed.Thus the optimal machining area of forging ZK61 magnesium alloy under the condition of temperature range 573⁶73K and strain rate range of 0.01s⁰.001s-1 was determined.（3）Under the condition of low temperature 323 K,the fracture of the specimen was observed;The original microstructure of wrought ZK61 magnesium alloy is coarse and the grain orientation is obvious.With the increase of strain rate,the dynamic recrystallization grain size increases and the grain growth occurs.The grain size increases with the increase of the ratio of height to diameter,and the grain size tends to be coarse and uneven.（4）The microstructure of the specimens was observed under different conditions.The results showed that the deformation temperature,strain rate and strain had significant effect on the microstructure of the hot compression specimens;There are obvious differences in the microstructure of the samples in different regions.Under the condition of complete forging,the dynamic recrystallization of the microstructure near the center of the specimen is more obvious.However,due to the small deformation of the specimen,the recrystallization is not obvious,and the growth trend is obvious.