焊接速度对铝合金/铜激光熔钎焊接头组织及性能的影响

Effect of Welding Speed on Microstructure and Properties of Aluminum Alloy/Copper Laser Welding-Brazing Joints

采用激光熔钎焊在不同焊接速度(4,5,6,7,8 mm·s^(-1))下对5052铝合金和T2铜进行对接焊,研究了焊接速度对接头宏观形貌、显微组织、显微硬度、抗拉强度及拉伸断裂机理的影响。结果表明:随着焊接速度增加,激光熔钎焊接头的焊缝成形先变优后变差,当焊接速度为6 mm·s^(-1)时焊缝成形最佳;随着焊接速度增加,接头中树枝状Al-Cu共晶组织变少,Zn-Al共晶组织变多,当焊接速度为6 mm·s^(-1)时接头铜侧界面反应区出现Al_(4)Cu_(9)和Al_(2)Cu金属间化合物,熔焊区由α-Al固溶体、η-Zn固溶体、Al-Cu共晶组织和Zn-Al共晶组织组成;随着焊接速度增加,铝合金/铜激光熔钎焊接头熔焊区硬度变化不大,铜侧界面反应区硬度下降,接头抗拉强度先增大后减小,拉伸断裂模式按照解理断裂、准解理断裂、韧性断裂、准解理断裂顺序依次变化,当焊接速度为6 mm·s^(-1)时抗拉强度(212 MPa)最大,接头发生韧性断裂。

The 5052 aluminum alloy and T2 copper were butt welded by laser welding-brazing at different welding speeds (4,5,6,7,8 mm·s^(-1)).The effect of welding speed on the macromorphology,microstructure,microhardness,tensile strength and tensile fracture mechanism of the joint was studied.The results show that with the increase of welding speed,the weld forming quality of laser welding-brazing joint first became better and then worse,and the weld forming quality was the best when the welding speed was 6 mm·s^(-1).With the increase of welding speed,the dendritic Al-Cu eutectic structure decreased and the Zn-Al eutectic structure increased.When the welding speed was 6 mm·s^(-1),Al_4Cu_(9) and Al_(2Cu) intermetallic compounds were formed in the copper side interface reaction zone of the joint,and the fusion welding zone consisted of α-Al solid solution,η-Zn solid solution,Al-Cu eutectic structure and Zn-Al eutectic structure.With the increase of welding speed,the hardness of fusion welding zone of the aluminum alloy/copper laser welding-brazing joint had little change,the hardness of copper side interface reaction zone gradually decreased,the tensile strength of the joint increased first and then decreased,and the tensile fracture mode changed from the cleavage fracture,quasi-cleavage fracture,ductile fracture to quasi-cleavage fracture in sequence.When the welding speed was6 mm·s^(-1),the tensile strength of the joint was the largest (212 MPa) and the fracture mode was ductile fracture.