Study On Microstructure And Mechanical Properties Of AZ31Mg Alloy Multi-pass Hot Rolling Process

Magnesium alloy are very attractive in aerospace industries、electronics andcars because of his low density. Rolling is a good way to form magnesium alloysheet,however,there are some problems, for example，rolling pass added、smallersingle pass deformation、low production efficiency,all those greatly limits thedevelopment of magnesium alloy. Therefore, research on rolling technology of highperformance magnesium alloy has important significance for promoting thedevelopment of magnesium alloy. In this paper, study on the relationship betweenrolling force and rolling process by multi-pass rolling, in order to improve theirmechanical properties.The evolving principle of the microstructure and mechanical properties forAZ31Mg alloy by multi-pass hot rolling with the thickness reduction of30%、25%、20%、15%,build relationship between rolling force and parameters. The results showthat: the best microstructure and mechanical properties can be obtained when Mgalloy plate with thickness of26mm was rolled to4mm under6passes at350℃and thickness reduction25%；The average grainsize of the last rolling-pass Mg alloysheet is17μm,elongtation is24%,yield strength is120MPa,tensile strength is233MPa.The unit rolling force continues to rise under thickness reduction30%and25%and shows cyclical changes under20%and15%with increasing rolling pass.Study on the affect of microstructure and mechanical properties by deformationdegree when rolling AZ31Mg alloy sheet at300℃and30%-60%,the result showsthat rolling My alloy has the best comprehensive mechanical properties at30%, theaverage grainsize is6μm,elongtation is25.1%,yield strength is160MPa,tensilestrength is255MPa.Rolling Mg alloy sheet at the temperature near by the dynamicrecrystallization(DRX) and big thickness reduction about30%to50%,the resultsshow that:AZ31B Mg alloy can be refined grain better and can acquire the bettermechanical properties, the average grainsize is form4.85μm to3.1μm,yieldstrength is250MPa,tensile strength is303MPa.