6061铝合金搅拌摩擦焊工艺窗口的研究

目的提高6061铝合金搅拌摩擦焊接头的质量,确定合适的工艺参数范围。方法设计3种不同的搅拌头进行焊接,分析接头拉伸强度与组织性能,并根据试验结果建立工艺窗口,选择合适的轴肩尺寸及工艺参数范围。结果随着轴肩尺寸减小,焊缝宽度、金属流动性、热力影响区面积均减小,在较大的焊接速度及较小的搅拌头转速下,焊缝底部出现缺陷;采用轴肩直径小的搅拌头进行焊接,在一定焊接参数范围内,焊接接头的拉伸强度得到提高;随着轴肩直径减小,焊核区晶粒组织细化,材料变形程度减小;由建立的工艺窗口可知,当轴肩尺为9 mm时,可选择的参数范围最大。结论焊接时采用小尺寸轴肩,可以在搅拌头行走速度更低、转速更大的情况下,仍然可以保持合理产热量,使接头性能得到提高。

Process Window of 6061 Aluminium Alloy Friction Stir Welding

This article aims to improve the quality of welded joints, determine the appropriate process parameter range of 6061 aluminum alloy friction stir welding. Stirring heads with different shoulder sizes were designed for welding. The tensile strength and microstructure of the joints were analyzed. Proper shaft shoulder sized and process parameter range were selected according to the process window established according to the test result. The weld width, metal fluidity, heat-affected zone decreased with the decrease of the shaft shoulder size. The bottom of the weld had defect at large welding speed and small stirring head speed; the strength of welded joints was improved under certain welding parameter range and small diameter shoulder. The grain structure of the weld nugget was refined, and the degree of material deformation was reduced with the decrease of the shaft shoulder diameter It can be seen from the process window established that the available process parameter range was the largest when the shaft shoulder size was 9 mm. A small shoulder diameter can maintain reasonable heat input and improve strength of welded joints even if at low welding speed and high rotation speed of the stirring head.