5056铝合金稳恒磁控激光深熔焊接过程熔池流动与传热行为分析  

Melt flow and thermal transfer of welding pool during static magnetic field supported deep-penetration laser beam welding of 5056 aluminum alloy

作　　者：陈纪城 陈小梅 常怡婷 刘学军[1,2] 魏艳红 CHEN Jicheng;CHEN Xiaomei;CHANG Yiting;LIU Xuejun;WEI Yanhong(Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China;Collaborative Innovation Center of Novel Software Technology and Industrialization,Nanjing 210023,China)

机构地区：[1]南京航空航天大学,南京210016 [2]软件新技术与产业化协同创新中心,南京210023

出　　处：《焊接学报》2021年第3期63-69,I0005,I0006,共9页Transactions of The China Welding Institution

基　　金：中国博士后科学基金面上项目(2020M671479);江苏高校优势学科建设工程资助项目(PAPD).

摘　　要：针对外加稳恒磁场条件下6 mm厚度5056铝合金激光深熔焊接过程,建立了热场—流场—电磁场耦合熔池瞬态动力学数值模型,求解了特定时刻温度场、速度场与电磁场分布,建立了熔池沿不同方向的Peclet数模型,分析了不同磁场感应强度对熔池流动与传热行为的影响.结果表明,稳恒磁场条件下熔池中产生显著的哈特曼效应,表现为液态金属Marangoni对流减弱,流速降低,热对流机制对熔池形貌的贡献减弱,使得熔池沿焊接方向长度明显收缩,固—液界面曲率减小;同时,磁控熔池表面及内部出现热迟滞效应,表现为液相峰值温度升高,温度梯度增大,热扩散速率提高,熔池的局部尺寸得以增大.铝合金磁控激光深熔焊过程焊缝形貌的变化是哈特曼效应与热迟滞效应共同作用的结果.The transient thermo-flow-electromagnetic dynamic numerical model was proposed for the simulation of deep-penetration laser beam welding of 6 mm thick 5056 aluminum alloy under an external static magnetic field.The transient temperature,velocity and electromagnetic fields were calculated and the modeling of Peclet number within the welding pool was conducted.The influence of varying magnetic flux densities on molten flow and thermal transfer behavior was analyzed.The results shown that,significant Hartmann effect could be induced in the weld pool with static magnetic field aligned,resulting in Marangoni convection compression,melt flow deceleration and intensity reduction of thermal convection.Accordingly,the weld pool length contracted along the welding direction,and the solid-liquid interface became less curved.Meanwhile,the thermal hysteresis effect occurred at weld pool surface and inside.The local molten metal was heated and the temperature gradient was increased,leading to the increase of thermal diffusion rate and local extension of weld pool dimensions.The variations of seam profile in magnetically supported laser beam welding attributed to the synthetic actions of Hartmann effect and thermal hysteresis.

关 键 词：5056铝合金 激光深熔焊 稳恒磁场 哈特曼效应 热迟滞效应 

分 类 号：TG456.7[金属学及工艺—焊接]