The Simulation Of The AZ31Magnesium Adiabatic Shear Behavior

Magnesium alloy is one of the lightest metal materials common used, it’s density isabout two-third of the aluminum, it has small density, high specific strength and stiffness,good damping, casting and cutting performance, it can be easily recycled and known as the"21st century green engineering materials". With magnesium alloys widely used inautomotive, aerospace, military weapons, and other industries, its dynamic mechanicsperformance is becoming more and more attention. The material under the condition of highstrain rate, the strength is bigger differences with the static load conditions. Differences arethe main causes of adiabatic shear band, which is produced inside of the materials under thehigh strain rate condition. The ASB cause carrying capacity of material greatly reduce, oreven completely lost.For further understanding the reason of AZ31magnesium alloy adiabatic shear bandproduce and the relationship between the internal hole and micro crack. In this paper,Ansys/Ls-dyna simulation software is used for numerical simulation of the SHPB dynamicloading process, stress strain curve is used for confirming the parameters of Johnson-Cookviscoplastic, the bullet initial velocity is obtained from the experiment data calculated. TheSHPB dynamic loading process is visual reconstructed, the way of stress transmission inSHPB device and AZ31bonnet sample ASB areas of stress and strain and temperatureconditions are being studied. Combined the technology of optical microscope, scanningelectron microscopy and transmission electron microscopy respectively for the AZ31undersame testing conditions, bonnet microstructure observation was carried out. Comprehensiveanalysis of the internal causes of the ASB and formation and evolution of the ASB internalorganization inAZ31bonnet sample.The experimental results show that the stress in SHPB device is transfer in the form ofwave, the speed is683.33m/s. When stress wave arrives, it firstly gathered at the area insideand outside the corners, and then gradually expand to the middle area, the maximum stressvalue is244.5MPa, the maximum temperature in this region is953.258K at the same time.the ASB is produced at the stress concentration area of AZ31bonnet samples with themicrostructure observation. the hole, micro cracks, isometric zone and parallel twins arefounded in ASB zone. Combined numerical simulation and experimental results, the high temperature condition in adiabatic shear band promote own tiny grain and substructure todynamic crystallization. Parallel twins locate both sides of isometric area. The isometricholes and micro cracks are exist in the interior of ASB. The hole is the first generation, withthe passage of time and load increasing, the crack is informed by hole.