Influence Of Dynamic Plastic Deformation On The Mechanical Properties Of Magnesium And AZ31 Magnesium Alloy

Dynamic plastic deformation can make a material deform with a huge strain rate,some mechanical properties could be achieved by sample adjustment of process witch can control microstructure characteristics of materials,at present,a variety of nano and super fine-grain face centered cubic metals and alloys has been developed using dynamic plastic deformation. The deformation ability of magnesium and its alloys under room temperature is poor,the deformation mechanism of dynamic plastic deformation and its influence on mechanical properties of pure magnesium and AZ31magnesium are discussed,dynamic plastic deformation method is used to get fine magnesium and its alloy so as to prove its mechanical properties.The influence of dynamic plastic deformation on magnesium and AZ31 magnesium alloy is researched by contrast experiments,mainly tension properties and hardness tests,researching in the micro mechanism of tension deformation by means of a serial analysis with metallographic examination microscope,X-ray diffraction,scanning electron microscope (SEM) and backscatter electron diffraction (EBSD) technology. As initial samples,pure magnesium has been pressed under 450℃and then annealed,dynamic plastic deformation is achieved under room temperature without anneal process,strain is 8%,quasi-static deformation is added for study in pure magnesium,defines four kinds of tension samples according to the angle between tension and C axis,respectively 0°,30°,60°and 90°samples,there are five tension rates. There are four samples according the angle between C axis and loading direction(LD) during dynamic plastic deformation experiment,however,the tensile direction are both perpendicular to the LD after dynamic plastic deformation,other tension conditions are the same as the initial pure magnesium. AZ31 magnesium alloy is attended by means of hot rolled followed with annealing,there are no twins but some large grains,and has a strong texture,the tension rate includes 0.01%/s,0.1%/s and 1%/s,there are four kinds of tension samples like initial pure magnesium. AZ31magnesium alloy deformed with different strain in dynamic plastic deformation experiments,and then developed new C axis,so the tension samples are defined according angles between tensile direction and new C axis,including 0°,30°,60°and 90°samples.Research shows that the texture of pure magnesium are changed after 8% dynamic plastic deformation except 0°sample,and new C axis parallel to the loading direction, many twin/matrix lamellar abrupt appear in 90°sample,the mean thickness is about 5μm,and large grains disappear,grains are in a uniformly distribution,although pure magnesium has a largest strength after dynamic plastic deformation,the elongation are decreased,however,the elongation of 90°samples dynamic plastic deformed are better than pressed under room temperature. The yield strength and tensile strength of AZ31magnesium alloy are improved after dynamic plastic deformation,in witch the texture are changed. Both strength and elongation are increased after dynamic plastic deformed 5%,but are decreased in other strain samples. Brittleness of AZ31 magnesium alloy is improved if the strain is small in dynamic plastic deformation.There are three main reasons for increase in strength for dynamic plastic deformed AZ31 magnesium alloy,the high dense dislocations and twin boundaries,as well as finer grains,the influence of dynamic plastic deformation on the elongations of pure magnesium and AZ31 magnesium alloy is based on high dense dislocations and twins,and their interactions,besides these tow actions,dynamic plastic deformation can refine grains and then improve the plasticity of materials.