Research on warm compound forming limit of AZ31 magnesium alloy sheet with quasi-static-dynamic impact fluid medium
On the basis of Nakazima hemispherical punch bulging test,the forming limit tests of AZ31 magnesium alloy sheet were con-ducted,and the forming limit distribution rules of AZ31 magnesium alloy sheet after warm compound forming with quasi-static-dynamic im-pact fluid medium was studied.The results show that the increase of temperature can increase the ultimate strain of AZ31 magnesium alloy sheet.Compared the ultimate strains under quasi-static and compound forming,it is found that the plastic forming performance of AZ31 magnesium alloy sheet is improved under quasi-static-dynamic compound forming.The results of scanning analysis on the fracture mor-phology under two different forming methods show that the quasi-static-dynamic compound forming has more and deeper dimples than the quasi-static forming.EBSD analysis was performed on samples with different forming methods at room temperature,100 and 200 ℃,and it is found that a small amount of { 10-12} tensile twins appear during compound forming at room temperature,resulting in coordinated deformation.At 100 ℃,compound forming introduces fine and thin tensile twin layers,cutting and refining grains,and improving plastic-ity compared with quasi-static forming.The generation of more recrystallized grains at 200 ℃ than quasi-static forming is the main reason for its better plasticity.
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