6082-T6/6005A-T6异种铝合金MIG焊接头的组织与性能

Microstructure and properties of 6082-T6/6005A-T6 dissimilar aluminum alloy joints made by MIG welding

对两种不同截面厚度的6082和6005A铝合金进行MIG焊接,借助显微硬度测试、拉伸性能测试、高频疲劳性能测试、OM、SEM、TEM等手段,对接头力学性能和微观组织进行研究。结果表明,焊缝中心为粗大的等轴晶,显微硬度较低;6082和6005A铝合金的热影响区均存在软化区,6005A铝合金侧热影响区的软化区是整个接头硬度最低的部位。焊接接头的抗拉强度和伸长率分别为201 N/mm^2和8.2%,断裂位置均在最薄弱的焊缝区和6005A铝合金侧软化区。设定应力比R=0,测试了接头的疲劳寿命,接头疲劳极限为101.27 N/mm^2。对疲劳断口观察分析,焊缝中的气孔易形成疲劳源,促进疲劳裂纹的萌生和扩展。

6082 and 6005 A aluminum alloys of different cross sectional thicknesses were welded by MIG. Mechanical properties and microstructure of dissimilar aluminum alloy welded joints were investigated by the microhardness test,the tensile test,the high-frequency fatigue test,OM,SEM and TEM. The results show that the joint center is coarse equiaxed microstructure and the microhardness is low. The softening zone exists in the heat-affected zone of 6082 and 6005 A aluminum alloy,and the softening zone in the 6005 A heat affected zone is the part with lowest hardness. The tensile strength and elongation of the welded joint are 201 N/mm^2 and 8. 2%,respectively. The weakest position locates at the weld zone and the softening zone of 6005 A aluminum alloy,where the tensile samples finally fracture. Fatigue life of aluminum alloy joints are tested with the stress ratio R = 0,and the fatigue limitof joint is 101. 27 N/mm^2. The fatigue fracture is observed and analyzed,the porosity in the welding tends to become a source of fatigue,which promotes initiation and propagation of fatigue crack.