基于激光毛化的铝合金/CFRTP激光连接特性研究

目的 针对目前铝合金和碳纤维增强热塑性复合材料(CFRTP)直接连接接头强度低的问题，对铝合金表面进行预处理，以提升异种材料的激光连接强度。方法 通过激光毛化工艺在铝合金表面预制微织构，然后利用光纤激光连接铝合金与CFRTP，研究了激光焊接工艺参数对铝合金与CFRTP焊接接头拉剪性能的影响。结果 当激光功率为750 W、焊接速度为0.2 m/min时，铝合金/CFRTP接头拉剪力达到最大值5 209 N，是未激光毛化的接头拉剪力的2.29倍。通过扫描电镜(SEM)对断口进行分析，发现界面断裂形式主要为CFRTP脱出和剪切断裂。采用SEM及能谱仪(EDS)对接头截面进行分析，发现结合界面处存在微观机械嵌合作用，同时在界面处存在元素过渡层。结论 随着激光功率的增大，焊接接头的拉剪力增大，但焊接功率较大会导致热输入过大，造成树脂发生热分解，导致焊接接头拉剪力降低。随着焊接速度的增大，焊接热输入降低，导致焊接过程中树脂熔化量减少，焊接接头的拉剪力降低。界面的机械嵌合作用使焊接接头具有较高的结合强度。

Laser Joining Characteristics of Aluminum Alloy/CFRTP Based on Laser Texturing

The work aims to deal with the low joint strength in direction connection of aluminum alloy and carbon fiber reinforced thermoplastic composites (CFRTP) to improve the laser connection strength of dissimilar materials. This paper prefabricated micro-textures on the surface of aluminum alloy through laser texturing process, and then used fiber laser to connect aluminum alloy and CFRTP. The effect of laser welding process parameters on the tensile and shear properties of aluminum alloy and CFRTP welded joints was studied. When the laser power was 750 W and the welding speed was 0.2 m/min, the tensile shear force of the aluminum alloy/CFRTP joint reached the maximum value of 5 209 N, which was 2.29 times that of the joint without laser texturing. Fracture analysis by scanning electron microscope (SEM) revealed that the interface fracture forms were mainly CFRTP prolapse and shear fracture. The analysis of fracture with SEM and energy dispersive spectroscopy (EDS) found that there was a micro-mechanical interlocking effect at the bonding interface, and there was an element transition layer at the interface. The results show that as the laser power increases, the tensile shear force of the welded joint increases, but when the welding power is high, the heat input will be too large, causing thermal decomposition of the resin, resulting in a decrease in the tensile shear force of the welded joint. As the welding speed increases, the welding heat input decreases, resulting in a decrease in the amount of resin melted during the welding process and a decrease in the tensile and shear stress of the welded joint. The mechanical interlocking effect at the bonding interface makes the welded joint have high bonding strength.