Dynamic Mechanical Properties And Failure Behavior Of WE43 Magnesium Alloy Under High Speed Impact Loading

Due to the light weight and high specific strength,magnesium alloys have been widely used in automobile,aircraft,medical and other industries.Due to the Magnesium alloys will show obvious tension compression asymmetry and anisotropy in the subsequent deformation process owing to the existence of strong texture after rolling or extrusion.Heat treatment is an effective method to improve the microstructure and mechanical properties of magnesium alloys.WE43magnesium alloy extrusion bar was used as the research object to study the dynamic mechanical properties and the effects of T4,T5 and T6 treatments on the dynamic mechanical propertie of magnesium alloy.Split Hopkinson Pressure Bar(SHPB)was used to study the dynamic mechanical properties of WE43 magnesium alloy samples in extrusion direction(ED)and extrusion radius direction(ERD)under high speed impact loading.The phase composition of WE43 magnesium alloy was confirmed by XRD analysis,and the microstructure and fracture morphology of the deformed samples were observed by scanning electron microscope(SEM)and metallographic microscope.The solid solution treatment temperature and holding time are 525?and 8hrs.,respectively,and the aging treatment temperature and holding time are 250?and16hrs.,respectively.The strain rates of the high speed loading deformation is controlled between1200s^-1and 2900s^-1,and the deformation temperature is at room temperature.The experimental results show that the extruded and T5 heat treated WE43 magnesium alloy have obvious anisotropy during high speed impact compression at room temperature,and the dynamic compression properties of ED direction samples are better than that of ERD.The anisotropy of WE43 magnesium alloy in T4 and T6 state is not obvious during high speed impact compression deformation at room temperature.Among the four states of extrusion,T4,T5 and T6,the T5 ED sample has the best dynamic compression performance.Many twins form in the microstructure after high speed impact compression,and the distribution of twins is not uniform,which indicates that twinning deformation occurs in the process of dynamic compression,and the deformation is not uniform.Increase the deformation strain rate,fine recrystallization structure and microcracks are observed.The adiabatic shear band was observed in the microstructure of T4sample.The cracks formed in the adiabatic shear band and recrystallization occurred near the cracks.After high speed impact compression,the fracture surface of WE43 magnesium alloy has the feature of brittle cleavage fracture,and fish scale pattern similar to"tire indentation"is observed in the fracture surface.In the micro fracture surface of T4 magnesium alloy,tearing and melting characteristics of fish scale pattern are also observed.