工艺参数对钛/铝异种合金回填式搅拌摩擦点焊连接质量的影响

Effect of Process Parameters on Mechanical Properties of Ti/Al Dissimilar Alloys by Refill friction stir spot welding

摘要:

采用回填式搅拌摩擦点焊工艺(Refill friction stir spot welding,FSpW)对厚度均为2 mm的5A02-O铝合金和TC4钛合金板材进行焊接。通过改变停留时间和回填速度,探究不同工艺参数对接头微观组织和力学性能的影响。结果表明,在选定工艺范围内,焊点成型良好,搅拌区晶粒细小,热影响区晶粒长大但有限,搅拌套作用区界面原子扩散距离比搅拌针作用区更大,停留时间6 s获得的焊点界面原子扩散距离和金属间化合物(IMC)厚度在1 μm左右。随着回填速度提高,接头承载载荷总体呈现上升趋势,但仍有数值波动,回填速度为30 mm/min,停留时间为6s获得接头拉剪载荷最低为4861 N,回填速度为90 mm/min,停留时间为6 s获得接头拉剪载荷最高为6617 N,拉剪后宏观断面较为平整,断裂模式为剪切断裂,微观断口由韧窝组成。

Abstract:

2 mm thick 5A02 aluminum alloy plate and 2 mm thick TC4 titanium alloy plate were jointed by refill friction stir spot welding (FSpW). The effects of different process parameters on the microstructure and mechanical properties were investigated by changing dwell time and refilling speed. Results show that within the selected process parameters, the sound joints were formed. The fine grains are formed in the stir zone and the grains in the heat thermo-mechanically affected zone are limited to satisfying extent. The atomic diffusion distance at the interface of the sleeve affected zone is larger than the pin affected zone. The atomic diffusion distance and the intermetallic compound (IMC) layer thickness at the interface of the joint are about 1 μm when dwell time is 6s. With the increase of the refilling speed, the tensile shear load of the joint increases. However, the changing trend is not obvious as the dwell time is kept constant at 2s. The tensile shear load strength is the minimum of 4861N at the welding condition of the refilling speed 30mm/min and dwell time 6s. When the refilling speed is 90 mm/min and dwell time is 6s, the tensile shear strength reaches the maximum of 6617N. The shear fracture mode is observed while the macroscopic fracture surface is relatively flat. The microscopic fracture is consisted of dimples.