【摘要】 目的研究激光熔丝增材制造过程的熔池流动特性,探究工艺参数对熔池流动与传热行为的影响。方法建立了考虑运动丝材持续送进过程的激光熔丝增材熔池传热和流动行为数学模型。针对316L不锈钢的激光熔丝增材制造,开展了成形过程中丝材送进、熔化和凝固行为的实验和数值模拟研究。结果模拟结果显示在成形过程中,准稳态阶段激光辐照中心的最高温度约为2500K。金属液主要由丝材端部向熔池尾部流去,并在熔池尾部凝固形成堆积体。同时,熔池表面最大速度可达0.8 m/s,并具有速度振荡特征。结论基于激光熔丝增材制造过程数学模型的模拟结果与实验吻合良好,结果表明,减小送丝速度会增大熔池表面高温区面积,并导致熔池的速度振荡程度增加。更多还原

【Abstract】 The work aims to study the molten pool flow behaviors in wire-based laser additive manufacturing and discuss the influence of different process parameters on fluid flow and heat transfer behaviors of molten pool. A mathematical model of heat transfer and fluid flow in the laser fuse additive process considering the feeding of the motion wire was established. For the wire-based laser additive manufacturing of 316 L stainless steel, the wire feeding, melting and solidification behaviors were studied by experimental and numerical simulation. The results showed that in the quasi-steady state stage, the highest temperature was located at the center of the laser irradiation, about 2500 K. The molten metal liquid mainly flowed from the wire end to the end of the molten pool, and solidified at the tail of the molten pool to form a deposit. The maximum speed of the molten pool surface can reach 0.8 m/s. The molten pool flow speed was in an oscillating state. The simulation results from the developed model of wire-based laser additive manufacturing are in good agreement with the experimental results. Decreasing wire feeding speed will increase the size of the high temperature zone on the molten pool surface, and result in the larger oscillation of the fluid flow speed.更多还原