摘要
研究不同等级的AA 5052-H32和AA 6061-T6铝合金搅拌摩擦成形连接的可能性。结果表明,当搅拌针压入深度为0.5~0.7 mm时,采用万能试验机测试得到的搭接剪切载荷为7.16 k N,横向拉伸载荷为3.51 k N,优于采用搅拌摩擦焊和搅拌摩擦点焊在相同材料上焊接的接头的性能。采用光学显微镜观察接头微观组织,发现接头的增强是由于机械销连锁或冶金结合。采用维氏硬度仪测量显微硬度,揭示搅拌针压入深度对搅拌区形成的作用和摩擦热流密度对低层金属薄片的影响。电子显微镜形貌显示,搅拌针压入深度对接头中机械销的形成和几何特征存在显著影响。不同的失效模式,例如销拔出、销剪切、部分结合分层和剥落,取决于不同的搅拌针压入深度形成的关键薄弱区。
The potential of friction stir forming for joining dissimilar grades of aluminum alloys namely,AA 5052-H32 and AA 6061-T6,was investigated.Study on the effect of tool plunge depth revealed that,lap shear load of 7.16 kN and cross-tensile load of 3.51 kN,recorded at medium tool plunge depth range from 0.5 to 0.7 mm,measured using a universal testing machine,were much larger than those of friction stir welded and friction stir spot welded joints fabricated on the same materials.Joint macrostructure observed with optical microscope revealed that joints were strengthened either by mechanical pin interlocking or by metallurgical bonding.The effect of tool plunge depth on the stir zone formation and the influence of frictional heat flux on the lower sheet were revealed through the microhardness measurement using Vickers hardness tester.Morphological studies revealed that tool plunge depth has a significant influence on the pin formation and the geometric features,generated in these joints.Occurrence of various failure modes such as pin pull-out,pin shear,partial bond delamination,and tear-off,were governed by the formation of critical weak zones at various tool plunge depths.
