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考虑熔池蒸气反冲压力、表面张力、热浮力等力学因素和熔池内、外部的对流、辐射等热学过程,采用沿深度方向衰减的旋转高斯体热源简化熔池对激光的吸收,采用流体体积法追踪气/液界面,采用液相体积分数法和焓-孔隙度法分别处理熔化凝固潜热及液-固糊状区的动量损失,建立了激光深熔焊接熔池的三维瞬态模型。运用该数学模型获得了不锈钢激光深熔焊接过程中熔池及小孔温度场和流场的瞬态变化。计算表明,熔池最高温度呈现线性增长、趋于平稳和小幅振荡三个阶段;小孔在焊接过程中呈现前倾和后倾两种姿态,且存在周期性振荡行为。计算得到的熔池形状和焊缝横截面的试验结果基本吻合,小孔振荡行为也从相关文献的实验结果中得到了验证。
Taking account of the mechanical factors such as recoil pressure, surface tension and thermal buoyancy of molten pool and the thermal processes such as convection and radiation inside and outside of the molten pool, the rotating Gaussian body heat source attenuating in the depth direction is used to simplify the absorption of laser light in the molten pool, Method was used to trace the gas / liquid interface. The liquid volume fraction method and the enthalpy-porosity method were used to deal with the latent heat of melting and solidification respectively and the momentum loss of the liquid-solid region. A three-dimensional transient model of the laser deep-weld pool was established. The transient changes of the temperature field and the flow field of the molten pool and the small hole in the stainless steel deep penetration laser welding were obtained by using the mathematical model. The calculation shows that the maximum temperature of the weld pool grows linearly and tends to be steady and slightly oscillated. The pinhole possesses two poses of forward and backward tilting during the welding process, and there is periodic oscillation. The calculated results of the shape of the weld pool and the cross-section of the weld basically coincide with each other, and the behavior of the orifice oscillation is also verified from the experimental results of the relevant literature.