自然时效对AZ31B电场扩散焊接头组织与性能的影响

Effect of natural aging on microstructure and properties of AZ31B joint prepared by field-active diffusion welding

采用中间添加铝粉的电场辅助扩散技术成功连接AZ31B镁合金。通过OM、SEM、XRD以及剪切实验等方法对比分析焊态和焊后自然时效处理状态下接头焊缝区的显微组织、元素分布、相组成和力学性能,探讨自然时效对镁合金电场辅助扩散焊接头组织和性能的影响规律。结果表明:在焊缝区形成一层与母材基体呈波浪状结合界面的镁-铝共晶反应层,反应产物主要由α-Mg、Al12Mg17和Al3Mg2金属间化合物组成;焊缝区显微硬度明显高于母材;经自然时效处理后接头的抗剪强度最大达60.3 MPa,比焊态下接头的最大抗剪强度(35 MPa)提高约72.3%。

Field-active diffusion welding technology was employed to join AZ31 B magnesium alloy using pure aluminium powder as interlayer. The microstructure feature,element distribution,phase component and properties of the as-welded and natural aging joints were investigated by OM,SEM,XRD and shear test. The effect of natural aging on microstructure and properties of the AZ31 B diffusion joints was analyzed. The results show that the Mg-Al eutectic layer formed in the weld zone is composed of α-Mg,Al12Mg17 and Al3Mg2intermetallic compounds. And the eutectic layer shows a wave bonding interface with the magnesium alloy substrate. The microhardness of the weld zone is higher than that of substrate. Furthermore,compared with the maximum shearing strength（35 MPa）of as-welded joint,the maximum shearing strength（60.3 MPa）of the joint after natural aging treatment increases by 72.3%.