为深入研究搅拌针形状对搅拌摩擦焊接头显微组织和拉伸性能的影响,采用搅拌针形状不同的搅拌头对8 mm厚2A14铝合金进行搅拌摩擦焊接试验,研究了搅拌针形状对接头显微组织和拉伸性能的影响.结果表明:增大搅拌针的“切边”深度,一方面可以增强搅拌针对材料的搅拌作用,促进材料塑性流动,有利于获得良好的焊接接头,另一方面可以增大搅拌针的动静态体积比,增强搅拌针对材料的挤压作用,增加材料的塑性变形产热,扩大焊核区及热机影响区的面积;焊核区“洋葱环”是材料流动充分的表现;搅拌针动静态体积比大于1对焊接接头拉伸性能的提高很重要,但当动静态体积比达到1.10后,继续增大动静态体积比对抗拉强度的提高效果不显著,但对断后伸长率的影响仍较明显.

In order to study the effects of stir pin shapes on microstructure and tensile properties of friction stir welded joint,friction stir welding tests were carried on 2A14 aluminum alloy with 8 mm thickness by stir tools with different pin shapes,and the effects of the shapes of stir pin on microstructure and tensile properties of the joint were studied.The results show that,increasing the "trimming" depth,on the one hand,could enhance the stirring action and promote the flow of the plastic material,and obtain a good welded joint,on the other hand,could enhance the ratio of dynamic volume to static volume,increase the extrusion action of stir spin on material and heat production of material deformation,increase the area of the nugget zone and thermo-mechanically affected zone.The "onion ring" in nugget zone is the performance of sufficient flow of material.The ratio of dynamic volume and static volume being over 1 is very important to the improvement of the tensile properties of the joint,but after the ratio up to 1.10,further increasing the ratio has no significant effect on the tensile strength,but still has evident effect on the elongation after fracture.