焊后时效处理对6082-T6铝合金搅拌摩擦焊接头的影响

对6082-T6铝合金搅拌摩擦焊接头进行自然时效和人工时效处理,通过透射电子显微镜、扫描电子显微镜、拉伸实验机和显微硬度计对组织演变和力学性能进行研究。结果表明:人工时效处理后显微硬度比焊态和自然时效高10~25HV,提高焊核区和热机影响区硬度效果明显好于自然时效。经过焊后自然时效、人工时效的焊接接头力学性能得到一定程度的提升,人工时效析出相比自然时效析出相抗拉强度提高12%,延伸率降低9%,人工时效提高拉伸强度效果更明显。人工时效处理后,焊核区组织发生显著变化,NZ主要为GP区,经过人工时效后NZ强化效应随团簇和GP区尺寸增大及数量增多而加强。HAZ主要为粗大的β′,经过人工时效后变化不大,硬度基本保持不变。通过对微观组织进行研究发现析出物的形状由界面能和应变能决定。

Effects of Post-weld Aging Treatment on Friction Stir Welding Joint of 6082-T6 Aluminum Alloy

Microstructure evolution and mechanical properties of friction stir welded 6082-T6 aluminum alloy during post-weld natural and artificial aging treatment were investigated by means of transmission electron microscope(TEM), scanning electron microscope (SEM), tensile test machine and Vickers hardness tester.The results show that microhardness of the joint after artificial aging treatment was about 10-25HV higher than welded and naturally aged alloy.Artificial aging was superior to natural aging on improving the microhardness of the nugget zone and heat affected zone.After post-weld natural aging or artificial aging treatment, the mechanical properties of welded joint was improved to certain extents.The tensile strength increased by 12% and elongation decreased by 9% after artificial aging, compared to natural aging.Artificial aging was more effective for tensile strength improvement.After artificial aging, the microstructure of the nugget had significant changes.NZ was mainly GP zone and the microhardness increased with the increase of the cluster size and the GP region after artificial aging treatment.HAZ was mainly coarse β′, but microhardness had little change after artificial aging treatment.It is found that the shape of precipitates can be determined by the interface energy and strain energy via microstructure analysis.