小搅拌针形状对搅拌摩擦焊6061铝合金显微组织和力学性能的影响

摘要

研究小搅拌针形状对6061铝合金搅拌摩擦焊接头的显微组织和力学性能的影响.采用3种不同形状的搅拌针:螺纹锥形圆柱形(T1)、三角形(T2)和正方形(T3).结果表明:不同形状的搅拌针会显著地影响焊接接头的性能.相对于使用其他形状的搅拌针,使用三角形搅拌针能获得最好的冶金和力学焊接性能.此外,使用正方形搅拌针制备的搅拌摩擦焊接头具有最低的拉伸强度和显微硬度.更小的搅拌针形状和轴肩直径导致热影响区域变窄和一定程度的软化.断口分析结果表明,不同形状的搅拌针焊接也能影响接头.断裂面显示三角形搅拌针制备的样品在拉伸试验中以韧性断裂形式失效,而在用其他形状的搅拌针(T1和T2)制备的接头中观察到了脆性断裂.%The effect of small tool pin profiles on the microstructures and mechanical properties of 6061 aluminum alloy joints using friction stir welding (FSW) technique was investigated. Three different tool pin profiles: threaded tapered cylindrical (T1), triangular (T2) and square (T3) were used to produce the joints. The results indicate that the weld joints are notably affected by joining with different tool pin profiles. The triangular tool pin profile produces thebest metallurgicaland mechanical weld properties compared with other tool pin profiles. Besides, the lowest tensile strength and microhardness are obtained for the joint friction stir welded with square tool pin profile. It is observed that the smaller tool pin profile and shoulder diameter lead to narrow region of heat affected zone (HAZ) and a desired level of softening. The fracture surface examination shows that the joints are also affected when welding with different types of tool pin profiles. The fracture surface shows that the triangular specimen fails with a ductile fracture mode during the tensile test, while the brittle fracture modes are observed in the joints fabricated with other tool pin profiles (T1 and T3).