高速列车用6005A-T6铝合金搅拌摩擦焊工艺研究

Study on the Friction Stir Welding Technology of 6005A-T6 Aluminium Used for High-Speed Train

研究了工艺参数对6005A-T6铝合金搅拌摩擦焊接头焊缝成形、微观组织以及力学性能的影响。结果表明,焊接速度以及搅拌头转速对接头力学性能具有明显影响。在焊接速度一定时,随着转速提高,接头力学性能提高,这与焊核区和热机影响区的固溶强化和塑性变形导致的位错密度增加有关;继续增大转速,接头力学性能下降,这是由于过大的热输入导致接头产生过时效现象。热影响区一直存在过时效现象导致其为接头的薄弱区域,拉伸试样断裂于该区域。在转速一定时,接头力学性能随焊接速度增大而增大。在本实验条件下,抗拉强度最大值为238 MPa,最小为214 MPa,分别达到母材的82.1%、73.8%。

The influences of welding parameters on weld formation,microstructure and mechanical properties were studied systematically for6005A-T6friction stir welded joint.The results show that the welding speed and rotation speed have a significant effect on welded joints.At a certain welding speed,the mechanical properties were improved with increasing rotation speed.This is attributed to enhancement of solid-solution strengthening and dislocation density due to plastic deformation.Further increasment of rotation speed led to the decrease of mechanical property,which was caused by the overaging of WZ and TMAZ due to excessive heat input.HAZ was the weak zone of welded joint because of overaging,in which the tensile specimens were all fractured.With increasing welding speed,the mechanical property increased at a certain rotation speed.The maximum and minimum tensile strength are238MPa and214MPa,which is82.1%and73.8%of the strength of base metal respectively.