摘要
利用双光束激光熔-钎焊焊接方法开展了AA7075/DP590异质金属的连接,通过改变激光功率等焊接工艺发现熔钎焊接头显微组织中存在金属间化合物(Intermetallic compound, IMC)层脱离铝-钢界面整体迁移进入焊缝内部的特殊现象,迁移现象位于激光直接作用区域,数值模拟发现激光直接作用下的熔池剧烈流动驱动了IMC的迁移。对迁移部分IMC层物相表征分析发现,近铝-钢界面处发生迁移的IMC层形貌呈致密平板状,与铝-钢界面处IMC层相似,由η相组成;迁移深入焊缝内部的IMC层内有裂纹、断裂产生,由θ相组成,裂纹处存在铝焊缝组织长入,发生迁移的IMC层内部存在η相与θ相的过渡区。拉伸结果表明,IMC层迁移现象的出现会削弱焊接接头铝-钢界面处的强度,这是因为界面初生的IMC层薄弱,止裂能力差,所以控制IMC层迁移有利于提高接头力学性能。
The joining of AA7075 aluminum alloy and DP590 steel are successfully conducted by dual beam laser welding brazing method. A unique phenomenon is found that the intermetallic compound(IMC) layer leaves Al/steel interface and migrates into welding seam. The migration of IMC layer only shows in the area where laser beam directly irradiates. Numerical simulation result shows the formation of such phenomenon is driven by the Marangoni Flow inside the welding pool induced by laser. It is found the migrated IMC layer near to Al/steel interface is composed of η phase and shows a compact flat morphology, which is similar to the IMC layer at Al/steel interface. On the contrary, the migrated IMC layer deep in welding seam is composed of θ phase and cracks are observed in such IMC layer with welding seam grows into cracks. There is a transition region for the η phase and θ phase inside the IMC layer. Tensile test results indicate that the migration of IMC layer will be harmful to the mechanical property of Al/steel interface because of the weak strength of newly-formed IMC layer. As a result, it’s better to avoid such phenomenon happening.
作者
袁锐
邓胜杰
崔海超
麻寕绪
芦凤桂
YUAN Rui;DENG Shengjie;CUI Haichao;MANinshu;LU Fenggui(Shanghai Key Laboratory of Materials Laser Processing and Modification,Shanghai 200240;School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240;Joining&Welding Research Institute,Osaka University,Osaka 567-0047,Japan)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2020年第6期33-40,共8页
Journal of Mechanical Engineering
基金
国家自然科学基金资助项目(U1660101,51675336)。
