2219铝合金双轴肩搅拌摩擦焊接头组织与性能分析

Microstructure and Mechanical Properties of Self-Reacting Friction Stir Welding of 2219 Aluminium Alloy

对2219铝合金进行了双轴肩搅拌摩擦焊工艺试验,详细分析了焊缝成型、接头组织形态及力学性能。结果表明:2219铝合金双轴肩搅拌摩擦焊缝正反面成型美观,内部无缺陷,几乎无焊缝减薄。接头宏观形貌呈典型的"哑铃型",焊缝上下表面宽,中间略窄。从显微组织角度看,接头的焊核区、热机影响区、热影响区等组织特征与常规搅拌摩擦焊相似。双轴肩搅拌摩擦焊接头显微硬度分布趋势与常规搅拌摩擦焊接头相似,均为典型的"W"型,但双轴肩搅拌摩擦焊接头不存在各层异性。接头力学性能试验表明:双轴肩搅拌摩擦焊接头抗拉强度达到了318.3 MPa,延伸率为5.5%。接头断口形貌呈典型的韧性断裂。

An extensive investigation was carried out on the SR-FSW of 2219aluminium alloy with the thickness of 6 mm, and the weld appearances, microstructure and mechanical properties of the SR-FSW joint has been ana- lyzed. The results indicated that the SR-FSW joint had excellent top and underside appearances without inner defects, distortion and seam thinning if the parameters were carefully chosen. Typical macrosections of the joint were slightly hourglass shpaed,and the width of the top and underside surface was slightly greater than the mid-thickness of the joint. As analyzed, the macrosection of the joint was related with the change of the SRPT, heat production and heat trasfer. The microstructure of the joint also consisted of nugget zone, thermal-mechanically affected zone, heat affect- ed zone, and within each zone, the microstructure was the same as C-FSW joint. The SR-FSW joint and C-FSW joint had the similar hardness distribution with the typical ＂W＂ type, but the former had no anisotropic. The mechanical property shown that the tensile strength of the joint can reach 318.3 MPa, and the ductility can get to 5.5%. The fracture meehanisium of the joint was ductile fracture.