铍材钎焊熔池动态行为的影响因素研究  

Study on Influence Factors of Transient Behavior of Laser Brazing Weld Pool of Beryllium

作　　者：史平安[1] 赵朋成[2] 莫军[1] 武传松[3] 郝志明[1] 

机构地区：[1]中国工程物理研究院结构力学研究所,绵阳621900 [2]青岛科技大学机电工程学院,青岛266061 [3]山东大学材料科学与工程学院,济南250061

出　　处：《机械工程学报》2011年第14期76-82,共7页Journal of Mechanical Engineering

基　　金：中国工程物理研究院重大基金资助项目(2005Z0302)

摘　　要：在综合分析激光钎焊的焊缝形状特征和热源作用特点的基础上,根据流体力学和传热学原理,建立瞬态熔池三维数值分析模型和混合热源分布模型,模型考虑熔池液态金属对流传热、熔池外工件的固态导热、焊接过程中的相变潜热、侧吹气流方式、对接界面的结构几何特性以及材料热物理性能参数随温度变化等因素。利用Visual Fortran语言编写数值分析程序,分析相变潜热、侧吹气流和对接间隙等对熔池内流场和温度场分布的影响。研究表明,相变潜热的影响不是总可以忽略的,尤其是在移动热源作用下相变潜热的影响比固定热源更为突出。侧吹气流主要是通过改变熔池内液态金属的流动状态进而影响到熔池的三维形态,因此,选择合适的吹气方式能够有效地提高激光钎焊的稳定性和焊深。间隙的存在造成温度场分布不连续造成熔池形状呈'钉头'形,考虑间隙时计算得到的熔池形状与试验结果吻合更好。With considering the geometry characteristic of laser brazing and analyzing the action features of heat source in laser brazing,a transient three-dimensional model of laser welding-brazing weld pool for beryllium is established on the basis of theories of fluid dynamics and heat transfer,in which a composite heat source constituted by double-ellipsoidal area heat source and Rotary-Gaussian body heat source along the z-direction is used to describe the heat flux source of a moving laser.Many factors are considered in the model including the convective heat transfer of liquid metal,solid heat conduction of workpiece outside the weld pool,latent heat in welding process,side assist gas orientation,the structure and properties of bonding interface,material thermo-physical properties as the function of temperature and so on.The program to simulate the transient variations of temperature field and flow field in laser brazing weld pool is developed by using Fortran language,and the effects of latent heat,the pattern of side assist gas and butt gap on fluid flow and heat transfer of weld pool are studied.The results show that the effects of the latent heat of phase change are not always negligible.In particular,the influence of the latent heat is more violent under moving laser beam action than under stationary laser beam.The gas flow rate and direction has an important effect on flow style and shape of weld pool,and the selection of side assist gas orientation can enhance the stability of laser brazing process and increase the depth of weld pool.The existence of gap makes the temperature field uneven and it is the decisive reason that the shape of weld pool looks like a nailhead.If the gap is taken into account,the shape of weld pool obtained from calculation will be in better agreement with the test result.

关 键 词：铍材 激光钎焊 熔池 流体流动 传热 

分 类 号：TG403[金属学及工艺—焊接]