基于超声搅拌的铝合金焊缝晶粒细化方法

A grain refining method of Al alloy welds with ultrasonic stirring

关键词:  6061铝合金  晶粒细化  超声搅拌

Key words:  6061Al alloy  grain refining  ultrasonic stirring

摘要:

细化焊缝晶粒可以显著提高焊缝的力学性能并可以有效防止凝固裂纹的产生. 由于板件在焊接过程中被牢固的固定在夹具上，通过超声振动待焊板件以细化晶粒的方法受到了很大的限制. 文中设计了一个全新的基于超声能量的焊缝晶粒细化方法，即将一根超声探针直接插入焊接熔池并进行超声搅拌. 结果表明，该方法在6061铝合金焊缝中得到了非常理想的晶粒细化效果. 晶粒细化范围随超声搅拌振幅的增大而增大，但晶粒尺寸随焊接速度的增大没有明显变化. 另外，6061铝合金超声搅拌焊缝的晶粒细化是通过异质形核和枝晶破碎两个机制共同作用实现的.

Abstract:

The mechanical properties and the solidification cracking resistance of the weld could be improved by grain refining. The grain refining method with ultrasonic vibration of workpiece was difficult when the workpiece is clamped down tightly to a rigid fixture or connected to a rigid structure. A new grain refining method with ultrasonic energy was designed, i.e., dipping an ultrasonic probe in the weld pool to stir it at a distance behind the arc. The results show that, this new approach produced effective grain refining in arc welds of 6061Al. Grain refining area increased with the ultrasonic amplitude increasing while the welding speed didn't affect the grain size effectively. Meanwhile, the grain refining of 6061Al welds were achieved with the combination effect of heterogeneous nucleation and dendrite fragmentation.