Investigation of weld parameters on ductility, onion ring and fracture behaviour of friction stir welded AA2219-T87

Abstract

Friction stir welding provides better retention of ductility and plasticity in comparison to fusion welding and it increases the stability against cracking. This study aims to enhance both the ductility and strength of the welded joints. Tool profile was found to play an important role in retaining ductility, understanding the metal flow behavior and determining the fracture initiating point. The microstructure of different regions in the onion ring was inferred to correlate the strength with the metal flow pattern. The onion ring pattern strengthened the weld nugget. Shoulder and taper threaded profile tool resulted in superior mechanical properties. Microhardness results confirmed that the fracture runs through low hardness areas such as heat affected zone and thermo-mechanically affected zone. The scanning electron microscopic images revealed elongated grains and dimples, justifying ductile mode of fracture.

摘要

与熔焊相比, 搅拌摩擦焊可以更好地保持材料的韧性和塑性, 提高焊接的抗裂稳定性。本研究 旨在提高焊接接头的延性和强度。刀具廓形在保持延性、分析金属流动行为和确定断裂起始点等方面 起着重要作用。分析了洋葱圆环不同区域的微观结构, 得出了洋葱圆环强度与金属流型的关系。结果 表明, 洋葱圆环强化了焊缝熔核。肩部和锥形螺纹型线刀具具有优异的力学性能。显微硬度数据表明, 断口经过热影响区和热机械影响区等低硬度区。扫描电镜图像显示了细长的晶粒和韧窝, 证实了断裂 为韧性断裂。