High Strain Rate Deformation Behavior Of Extruded Mg-1Zn-2Y Magnesium Alloy

Magnesium alloy is widely used in ground transportation,aviation and aerospace engineering,but the dynamic compressive mechanical behaviors of magnesium alloy at high temperature and high strain rate are not much,most of the research is mainly aimed at high temperature and low strain rate conditions.However,in some areas such as plant explosion,explosion of terrorist attacks,sudden fire and other occasions,metal materials are likely to suffer impact load condition at high temperature and high strain rate,so the research of dynamic mechanical properties at different temperature and high strain rate is very important.In this paper,use the Split Hopkinson Pressure Bar to deeply study of the mechanical behavior,the deformation and failure mechanism of Mg-1Zn-2Y magnesium alloy at room temperature and high temperature and high strain rate.In this paper,In the light of extruded Mg-1Zn-2Y magnesium alloy at room temperature,100℃,150℃ and 200℃ and the loading direction of ED and ERD conduct the high-speed impact compression test,the strain rate range of 1290-3047s^-1;respectively using optical microscope（OM）and scanning electron microscopy（SEM）to analysis the microstructure before and after deformation;use of the χ-ray to analysis the texture;using the scanning electron microscopy（SEM）to analysis the fracture after impact test.Accordingly,discussed the deformation and fracture mechanism of Mg-1Zn-2Y magnesium alloy.The experimental results show that the samples at the loading direction of ED and ERD are all yield at room temperature（ERD direction yield point is not obvious）.At room temperature,the ED sample shows positive strain rate strengthening effect,the loading direction of ERD shows positive strain rate strengthening effect only at 1290-1552s^-1,but the stress is not sensitive to the strain rate at 1552-2602s^-1,the strain rate sensitivity of ERD is lower than ED,the yield strength of ED is lower than ERD in contrast,the strain rate strengthening effect of ED is more significant than ERD,and the fracture strength of ED is higher than ERD,but the fracture strain is lower than ERD.In addition,the true stress strain curves along ED direction is concave first and then convex,and there is no inflection point along the ERD direction,and the convex curve.The yield strength of Mg-1Zn-2Y magnesium alloy under high temperature is insensitive to the change of strain rate.the plastic of ED direction is better than ERD in contrast,and the impact absorbing energy is greater than ERD,showed a relatively stable strain rate strengthening effect,but the strain rate strengthening effect and adiabatic shearing sensitivity of ERD is greater than ED.No matter at room temperature or high temperature,the flow stress of extrusion Mg-1Zn-2Y magnesium alloy along loading direction of ED is higher,this is related to texture,the high strain rate fracture characteristics of Mg-1Zn-2Y magnesium alloy at room temperature and 100℃ is ductile brittle coexist,it’s cleavage fracture,and the fracture degree along different loading directions is difference.