Study On The Formability Of Nonisothermal Stamping Magnesium Alloy AZ31 Sheet With Complex Section

AZ31 rolled sheet can be used in magnesium alloy stamping.The products have high production efficiency,mechanical property and surface quality.It has market advantage and good prospect.Because of the close-packed hexagonal structure and less slip system, AZ31 have low plasticity.Fracturing occurs in room temperature.Studying AZ31 sheet formability and forming process is the key point of product application and quality.The article takes AZ31 rolled sheet as research object,analyzed forming temperature, rate and their effects on magnesium alloy stress and strain through warm tensile test. Magnesium alloy have good elongation in low strain rate around 200℃～280℃.By analyze the relationship of temperature,strain rate and flow stress,Fields and Backofen equation parameters were modified and the mathematic model about the flow stress of AZ31 magnesium alloy sheet was developed.The microstructure grain size of the low rate forming AZ31 was smaller then original state and the necklace microstructure was show.In the base of the mathematic model of AZ31,warm forming of AZ31 was simulated with DEFORM-3D software.Through the analysis of forming temperature,velocity,blank holder force,lubrication condition to study the effect on material flow,defect formation and fracture toughness in forming of AZ31 complex section.The optimum forming conditions were determined:the temperature of male die is 200℃and the female die is 250℃.Drawing velocity is 1mm/s,the blank holder is 3t,the lubrication coefficient is 0.25.According to the result of warm tensile test and numerical simulation,a character of AZ31 magnesium alloy computer case was analyzed.The forming process was made and the warm forming mold and the temperature control system were designed.Using the designed warm forming mold and the temperature control system to study the male die and the female die temperature,pouch velocity,blank holder,oil lubrication.est.and their effect on stamped AZ31 magnesium alloys sheet.It is found that warm forming of AZ31 magnesium alloy is influence by the male die and the female die temperature.Wrinkling occurs in corner when forming below 120～180℃,and fracturing of comer is above 280℃.Magnesium alloy AZ31 can be stamped around 220℃～250℃with the condition of differential temperature mold,elastic binding,oil lubrication and low speed drawing.The AZ31 magnesium alloy computer case with good product quality can be formed successfully.