带状组织对铝/镁异种金属搅拌摩擦焊接头力学性能的影响  

Effect of banded structure on mechanical properties of aluminum/magnesium dissimilar metal friction stir welding joint

作　　者：朱浩[1] 张二龙 莫淑娴 马泽铭 王军[2] ZHU Hao;ZHANG Erlong;MO Shuxian;MA Zeming;WANG Jun(Shijiazhuang TIEDAO University,Shijiazhuang,050043,China;Hebei University of Science and Technology,Shijiazhuang,050018,China)

机构地区：[1]石家庄铁道大学,石家庄050043 [2]河北科技大学,石家庄050018

出　　处：《焊接学报》2020年第1期34-38,66,I0003,共7页Transactions of The China Welding Institution

基　　金：国家自然科学基金资助项目(51705344);河北教育厅重点项目(ZD2019102).

摘　　要：采用搅拌摩擦焊(FSW)对厚度为4 mm的6061铝合金与AZ31B镁合金进行不同工艺的平板对接试验.采用光学显微镜(OM)、扫描电镜(SEM)、X射线衍射仪(XRD)及能谱仪(EDS)对接头进行微观组织观察,采用电子万能试验机对接头力学性能进行测试.结果表明,在接头焊核区(WNZ)中存在着明显的带状组织,带状组织是由插入镁基体中的铝合金条以及弥散分布在条带上的金属间化合物(IMCs)组成;IMCs主要为Al12Mg17和Al3Mg2;铝/镁异种金属FSW接头裂纹形核和扩展均发生在带状组织内;焊接工艺影响带状组织形态和IMCs尺寸及数量;随着转速(n)的增加或焊接速度(v)的降低,带状组织呈弯曲状,长度相对较短且呈不连续分布;当转速(n)过高或焊接速度(v)过低时,带状组织变细,但IMCs数量增多且尺寸变大;铝/镁异种金属FSW接头强度主要取决于带状组织形态和IMCs尺寸及数量.The flat butt welding tests of different processes for 6061 aluminum alloy and AZ31B magnesium alloy with thickness of 4 mm were carried out by friction stir welding(FSW).Microstructure of the joints was observed and analyzed by optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction(XRD)and energy dispersive spectrometer(EDS),mechanical properties of the joints were tested by electronic universal testing machine.The results show that,there are obvious banded structures in the weld nugget zone(WNZ),which are composed of aluminum slices inserted in the magnesium matrix and IMCs dispersed on the band.The types of IMCs are Al12Mg17 and Al3Mg2.Crack nucleation and propagation of aluminum/magnesium dissimilar metal FSW joints occur among the banded structure.Welding technology affects the morphology of banded structure and size and quantity of IMCs.With the increasing of rotational speed(n)or the decreasing of welding speed(v),the banded structure in the joint WNZ are curved,relatively short in length and discontinuously distributed.The banded structure becomes thinner,but the quantity of IMCs increase and the size becomes larger when the rotation speed(n)is too high or the welding speed(v)is too low.The ultimate strength of aluminum/magnesium dissimilar metal FSW joint mainly depends on the morphology of the banded structure and the size and quantity of IMCs.

关 键 词：铝/镁异种合金 搅拌摩擦焊 带状组织 力学性能 

分 类 号：TG457.14[金属学及工艺—焊接]