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对AA6111铝合金电阻点焊接头的显微组织、显微硬度和准静态失效行为进行分析。利用光学金相显微技术和高分辨率硬度测量方法对接头的焊核区、热影响区和母材金属区进行表征。结果表明,焊核区的硬度低于母材金属区的,热影响区的硬度高于或接近于母材金属区的。母材金属板材的硬度沿厚度方向发生变化,为准确分析焊接工艺对接头性能的影响,这种变化需考虑在内。通过准静态搭接剪切试验得到焊接接头的失效载荷和失效模式。所有接头以结合面断裂方式破坏,这种失效模式与焊核区的低硬度现象一致。
The microstructure, microhardness and quasi-static failure behavior of AA6111 aluminum alloy resistance spot welded joints were analyzed. The weld nugget, heat affected zone and base metal zone of the joint were characterized by optical metallographic microscopy and high resolution hardness measurement. The results show that the hardness of the nugget core is lower than that of the base metal and the hardness of the heat affected zone is higher or closer to that of the base metal. The hardness of the base metal sheet varies along the thickness. To accurately analyze the effect of the welding process on the properties of the joint, such changes need to be taken into account. Through the quasi-static lap shear test, the failure load and failure modes of welded joints are obtained. All joints are broken by the joint fracture, which is consistent with the low hardness of the weld zone.