航空学报 > 2022, Vol. 43 Issue (4): 525240-525240   doi: 10.7527/S1000-6893.2021.25240

选择性激光熔化过程中熔池演变与金属飞溅特性数值模拟

曲睿智1,2, 黄良沛1,2, 肖冬明3   

  1. 1. 湖南科技大学 机电工程学院, 湘潭 411201;
    2. 湖南科技大学 机械设备健康维护湖南省重点实验室, 湘潭 411201;
    3. 佛山科学技术学院 机电工程与自动化学院, 佛山 528225
  • 收稿日期:2021-01-11 修回日期:2021-01-29 发布日期:2021-05-10
  • 通讯作者: 黄良沛 E-mail:huanglp413@163.com
  • 基金资助:
    国家自然科学基金(51875195,52075163)

Numerical simulation of melt pool evolution and metal spattering characterization during selective laser melting processing

QU Ruizhi1,2, HUANG Liangpei1,2, XIAO Dongming3   

  1. 1. School of Mechanical and Electrical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China;
    2. Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment, Hunan University of Science and Technology, Xiangtan 411201, China;
    3. School of Mechatronics Engineering, Foshan University, Foshan 528225, China
  • Received:2021-01-11 Revised:2021-01-29 Published:2021-05-10
  • Supported by:
    National Natural Science Foundation of China (51875195, 52075163)

摘要: 选择性激光熔化(SLM)成形技术是新型增材制造技术的一个重要发展领域。通过建立用于选择性激光熔化成形的高保真粉末尺度激光熔化模型,展现了粉末层从开始熔化、熔滴飞溅到熔道成形、冷却凝固的全过程。熔滴飞溅行为是金属粉末层熔合工艺中难以避免的成形缺陷来源,借助数值模拟手段还原了激光熔合过程中飞溅现象的演变过程,克服了实际实验难以捕捉到熔池内部及熔滴飞溅行为定量表征信息的难题,获取了熔融液滴飞溅的变形机制以及飞溅过程中随时间变化的温度、速度、压力、位置偏移等信息。结果显示,金属蒸气作用与惰性气体流动共同驱动了熔池流动与熔滴的飞溅行为,高温熔体流速为1~6 m/s,熔滴飞溅速度为1~4 m/s。随着工艺参数的调整,飞溅熔滴的体积形态与飞溅方向均发生变化。结合实验分析,追踪了熔滴飞溅的运动轨迹以及熔滴在空中飞溅时的"二次爆炸"与"旋球"行为。该研究补充了实际实验对于飞溅行为的分析理解,通过提取飞溅物完整寿命周期能量吸收耗散的量化信息,进一步促进了激光熔合过程中复杂的流体流动与飞溅现象的动力学表征。

关键词: 选择性激光熔化, 金属粉末, 飞溅, 熔池演变, 316L不锈钢, 离散元法

Abstract: Selective Laser Melting (SLM) forming technology is an important development area of new additive manufacturing technology. A high-fidelity powder-scale laser melting model for SLM is developed to show the whole process of from the beginning of melting and droplet spattering to melt channel forming and to cooling and solidification of the powder layer. The spattering behavior of the molten droplet is an unavoidable source of forming defects in the metal powder layer fusion process. With the help of numerical simulation, the evolution of the spattering phenomenon in the laser fusion process was restored, overcoming the problem that the quantitative characterization of the internal and droplet spattering behavior of the melt pool cannot be obtained from actual experiments, and obtaining the information on the forming mechanism of the molten droplet spattering as well as information on the temperature, velocity, pressure and position shift over time during the spattering process. The results show that metal vapor action and inert gas flow jointly drove the melt pool flow and droplet spattering behavior, with the velocity of the high temperature melt flow ranging from 1 m/s to 6 m/s and the velocity of the droplet spattering ranging from 1 m/s to 4 m/s. With the adjustment of process parameters, the volume morphology and spattering direction of the spattering droplets changed. Based on the experimental analysis, the trajectory of the molten droplets and the ‘secondary explosion’ and ‘spinning ball’ behaviors of the molten droplets during the airborne spattering were captured. This study is a complement to the analytical understanding of spattering behavior from actual experiments, and further contributes to the kinetic characterization of complex fluid flow and spattering phenomena during laser fusion by extracting quantitative information on energy absorption/dissipation of the complete life cycle of the spatter.

Key words: selective laser melting, metal powder, spatter, molten pool evolution, 316L stainless steel, discrete element method

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