Numerical Simulation and Experiment of Single Track Scanning and Lapping in Selective Laser Melting

doi:10.3901/JME.2020.22.056

Abstract

Abstract: In the numerical simulation of selective laser melting(SLM) single track scanning, the geometrically regular solid model is often used to simulate the powder layer, and the coexistence of powder and gas in the powder layer is simulated by equivalent definition of material thermophysical properties. It is difficult to simulate the randomness of the scanning results caused by the randomness of powder particles, and it is difficult to analyze the shape and inner of the molten pool micro evolution process of micro defects. In view of the influence of laser power and lap ratio of single track on the quality of single track and lapping in SLM forming process, numerical simulation models of single track and the lapping of single track in the first layer process of SLM are established with 316L stainless steel as an example. The powder spreading process of SLM is established in EDEM based on the discrete element method, and the numerical powder bed geometry model is obtained. The simulation of SLM single pass scanning and lapping is based on the finite volume method, which is implemented in FLUENT. The two-phase flow model and the solidification/melting model are used to capture the changing process of the molten pool morphology, and the numerical models of single track and lapping of single track in different laser power and scanning lapping ratio are obtained. At last, the formation of the single track surface morphology and defects under the laser power of 100-300 W is illustrated. When the laser power is 100-150 W, the morphology of single track is irregular and easy to form local defects. When the laser power is 200-300 W, the higher the laser power is, the smaller the minimum lapping ratio is to ensure the lapping quality. When the laser power is 250 W, the single track filling spacing should be no more than 0.1 mm. The research results have important reference value for the adjustment and optimization of SLM process parameters.

Key words: selective laser melting, numerical simulation, single track scanning, lapping

CLC Number:

TG665

LIANG Pinghua, TANG Qian, FENG Qixiang, SONG Jun. Numerical Simulation and Experiment of Single Track Scanning and Lapping in Selective Laser Melting[J]. Journal of Mechanical Engineering, 2020, 56(22): 56-67.

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