铝合金搅拌摩擦焊焊核紊流区及性能分析

采用搅拌摩擦焊方法对2219-T6铝合金进行焊接,对焊接接头的宏观形貌、微观组织、抗拉强度进行了分析,并通过对焊核塑性金属的流动状态进行分析,研究了搅拌摩擦焊接头强度弱化的原因. 结果表明,焊核根据流态可分为3个不同的区域,其中靠前进侧存在一个性能薄弱的B区域,该区的产生是抽吸挤压作用不平衡的结果,也是塑性金属向上回流通道. 该区具有较大的塑性损伤,易产生疏松缺陷及界面突变,晶粒具有较大的热不稳定性,是造成接头强度低于母材的主要原因之一. 通过高温短时的再结晶热处理工艺可以恢复该区域的强韧性,消除弱化问题.

Analysis of turbulent flowing zone in friction stir welded aluminum alloy weld nugget

A 2219-T6 aluminum alloy plate was welded by friction stir welding, and the morphology, microstructure and mechanical properties of the joint were investigated correspondingly. Through analyzing the flowing pattern of the plastically deformed metal in the nugget zone, the strength weakening of the joint were analyzed and summarized. The results show that the welded nugget is divided into three different regions according to the flowing pattern of plastic metal, and a turbulent flowing region is produced by unbalanced suction and extrusion of plastic metal at the front side of joint. This region with weak mechanical properties is a channel for the back flow of plastic metal. The weakening strength is due to the plastic deformation induced damage of the metal, which resulted in the formation of defects and the mutational interface. Moreover, grains in the turbulent flowing region presented large thermal instability. After the recrystallization heat treatment, the joint can restore the ductility, which will improve the mechanical properties of the joint.