【摘要】 激光深熔焊接的传热过程包括热传导和焊接熔池内熔融材料的对流流动。考虑了熔池的对流和材料热物性参数的温度依存性,建立了激光深熔焊接的三维传热模型,以试验所得小孔为原型;考虑了熔池中流质的轴向流动及轴向的温度变化;采用了"固液同一法",让温度低于液相线的材料粘性系数趋于无限大,而高于液相线的材料则采用实际值。采用有限单元法对模型数值求解的结果表明,激光焊接温度中的等温线为一组类似椭圆的曲线;小孔前沿的温度梯度、速度梯度大;后沿的温度梯度、速度梯度小;焊接熔池中的对流流动是在表面张力驱动下产生的。更多还原

【Abstract】 The heat transfer in laser deep penetration welding includes heat conduction and convection in the welding pool.A 3D heat transfer model in laser deep penetration welding was developed.The main characteristics of the model has some characteristics as follows:(1)A prototype of the keyhole in the model was obtained from the experiments.(2)The convection and the temperature distribution in the depth were considered.(3)The same law in the solid and the liquid region,i.e.the viscosity of the material in the solid region was infinite;however the viscosity of the material in the liquid region was set to actual value.The model was solved by a finite element method,and the results show that:The isotherms in laser welding are shaped as ellipses.The temperature gradient and the velocity gradient on the front keyhole wall are greater than those on the rear keyhole wall.The convection flow in the welding pool is driven by the surface tension.更多还原