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为了研究激光熔覆过程中熔池内的温度场特征及其对凝固后的微观组织的影响,建立了描述熔覆过程的对流扩散固液相变统一的数学模型,模拟了激光熔覆过程中熔池在不同时刻的温度场和速度场,计算出熔覆层内不同位置的温度梯度、冷却速度和凝固速度。计算结果表明,熔池内液体的流动对熔池内温度场分布有较大影响。距离熔覆层顶部越远,冷却速度减小,温度梯度增大,凝固速度减小。这种温度场特征决定了从熔池底部到顶部的凝固组织类型及组织大小的变化特征,并据此对熔覆层的凝固组织类型进行预测,与实验结果吻合良好。
In order to study the temperature field in the molten pool and its effect on the microstructure after solidification, a unified mathematical model describing the convection-diffusion solid-liquid phase transition was established to simulate the melting The temperature field and the velocity field of the pool at different times calculate the temperature gradient, the cooling rate and the solidification speed at different positions in the cladding layer. The calculation results show that the flow of liquid in the molten pool has a great influence on the temperature distribution in the molten pool. The farther away from the top of the cladding layer, the cooling rate decreases, the temperature gradient increases, and the solidification rate decreases. The characteristics of the temperature field determine the characteristics of the solidified structure and the size of the structure from the bottom to the top of the molten pool, and predict the solidified structure of the cladding according to the characteristics of the temperature field, which is in good agreement with the experimental results.