7A19铝合金搅拌摩擦焊组织性能分析

Microstructures and mechanical properties of friction stir welding joint of 7A19 aluminum alloy

研究了不同焊接规范参数对退火态和T6态7A19铝合金搅拌摩擦焊接头的金相组织、硬度分布及力学性能影响。结果表明,7A19铝合金的搅拌摩擦焊焊接性能良好。焊缝金相致密无缺陷,焊核区的微观组织是无方向性的、细小的等轴晶粒,热影响区晶粒被拉长。焊缝区硬度分布均匀,与母材相比没有明显的下降。热影响区是接头的脆弱区,接头拉伸强度随着焊接热输入的降低而增加。采用合适的焊接参数,7A19铝合金在退火态下进行焊接,接头效率能达到母材的89.6%,断后伸长率为8.7%;在T6态下进行焊接,接头效率能达到母材的85%,断后伸长率为6.7%。

The influences of friction stir welding parameters such as welding pressure,rotational speed,and traverse speed on microstructure and mechanical properties of 7A19 Al alloy welded joint were investigated.The experiments demonstrate that 7A19 Al alloy can be welded well by friction stir welding.The analysis on microstructure show that the dynamic recrystallization occurs in the weld nugget zone.There is no obvious heat-affected zone in the joint.The thermo-mechanical affected zone exhibits curved band-like characteristics.Hardness measurement results show that there is no obvious softened zone in the joint.Tensile tests show that the increase of the ratio of the rotation speed to traverse speed will lead to the decrease of the mechanical properties.The average tensile strength can get to 89%of that of the annealed 7A19 base metal and 84.9%of that of the solution and ageing strengthened 7A19 base metal.