Mesoscopic Numerical Simulation during Selective Laser Melting of Maraging Steel

doi:10.3901/JME.2024.03.282

Abstract

Abstract: Selective laser melting (SLM) involves a variety of complex physical phenomena that occur at the mesoscale, and these complex physical mechanisms during processing are difficult to be uncovered using experimental methods. A mesoscopic heat-coupled numerical model for the SLM process of 18Ni-300 maraging steel is developed based on discrete element and finite volume methods, and the model is verified by comparison with track fabrication experiments. Numerical simulations are performed to reveal the basic characteristics of single-track SLM processing, including the morphology of the tracks, the dimensions and temperatures of the molten pool and the heat transfer mechanisms, when the laser power is increased from 60 W to 270 W. The influence of different combinations of laser power and scanning speed at the linear energy densities of 0.2 J/mm, 0.3 J/mm and 0.45 J/mm on the morphology of the tracks, molten pool dimension and the heat transfer mechanism is investigated. Furthermore, the theoretical critical hatch spacing without overlap defects for the laser power of 180 W and scanning speed of 600 mm/s is calculated to be 83 μm based on the theoretical relationship of track overlaps, and the behaviour and evolution of track overlaps during multi-track and multi-layer SLM processing are investigated at the hatch spacing of 80 μm, 100 μm and 120 μm. The developed model can not only guide single-layer/multi-layer processing experiments, but also be used to predict process parameter windows and improve the efficiency of process optimisation..

Key words: selective laser melting, maraging steel, numerical simulation, molten pool, defect

CLC Number:

TG665

ONG Jun, TANG Qian, LUO Zhichao, FENG Qixiang, NIE Yunfei, REN Zhihao. Mesoscopic Numerical Simulation during Selective Laser Melting of Maraging Steel[J]. Journal of Mechanical Engineering, 2024, 60(3): 282-295.

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