激光深熔焊中熔池-小孔的动态行为模拟

发布时间：2018-06-24 13:57

本文选题：激光深熔焊 + 光线追踪法　；参考：《材料热处理学报》2015年07期

【摘要】：为了准确的模拟出激光深熔焊接中小孔的动态变化过程,根据小孔内激光的能量吸收机制,采用Particle Level Set方法和有限差分模型的光线追踪法来描述小孔对激光能量的吸收作用,建立了描述激光深熔焊接过程中熔池动态行为和小孔瞬态演化行为的三维数值模型。动态模型中考虑了菲涅耳吸收、蒸发潜热、凝固/熔化潜热和熔池内液态金属的耦合对流传热等物理因素,以及反冲压力、表面张力和热毛细力等力学因素的影响。通过对30Cr Mn Si A钢激光焊接过程的数值模拟,得到了动态焊接过程中小孔深度的变化规律和小孔的形貌特征、能量分布特征。研究表明,小孔动态演化过程可分为3个阶段:小孔深度线性增长阶段、振荡增长阶段和高频振荡阶段。不同阶段小孔的振荡方式和程度不同,进而造成小孔的形貌和孔壁的能量密度分布也不同。而小孔的振荡也是焊接不稳定性和缺陷形成的重要原因。
[Abstract]:In order to accurately simulate the dynamic process of the small hole in laser deep penetration welding, according to the energy absorption mechanism of the laser in the hole, the Particle level set method and the ray tracing method of the finite difference model are used to describe the absorption of the laser energy by the small hole. A three dimensional numerical model is established to describe the dynamic behavior of molten pool and the transient evolution of holes during laser deep penetration welding. The physical factors, such as Fresnel absorption, latent heat of evaporation, solidification / melting latent heat, coupled convection heat transfer of liquid metal in molten pool, as well as mechanical factors such as recoil pressure, surface tension and thermal capillary force, are considered in the dynamic model. Through the numerical simulation of the laser welding process of 30Cr mn Si A steel, the variation law of the hole depth and the characteristics of the morphology and energy distribution of the holes in the dynamic welding process are obtained. The results show that the dynamic evolution of the pores can be divided into three stages: the linear growth stage of pore depth, the stage of oscillation growth and the stage of high frequency oscillation. The shape of the pore and the distribution of the energy density of the pore wall are also different due to the different oscillation modes and degrees of the pore at different stages. The oscillation of small hole is also an important reason of welding instability and defect formation.
【作者单位】：中国工程物理研究院总体工程研究所;华中科技大学材料科学与工程学院;
【基金】：中国工程物理研究院重大基金(2013A0203008) 中国工程物理研究院“计算固体力学”重点学科项目
【分类号】：TG456.7

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