Molten pool behaviour and its physical mechanism during selective laser melting of TiC/AlSi10Mg nanocomposites: simulation and experiments

With superior flexible manufacturing capability, selective laser melting (SLM) has attracted more and more attention in the aerospace, medical, and automotive industries. However, the poor quality of the lower surface in overhanging structures is still one of the factors that limits the wide application of SLM. In this work, the influence of process parameters and scanning strategy on the lower surface quality of SLMed TA15 (Ti-6Al-2Zr-1Mo-1V) titanium alloy parts were studied. The results showed that the laser surface energy density (EF) had a significant influence on the quality of the lower surface. Excessive EF led to obvious sinking of the molten pool and a serious slag hanging phenomenon. However, the too low EF easily contributed to the insufficient powder fusion in the lower surface area, which led to the agglomeration of a molten pool during core processing, resulting in slag hanging, pores, and powder spalling that reduced the quality of the lower surface. Moreover, the cross-remelting strategy and non-remelting strategy gained better surface quality at the low EF and high EF, respectively. In addition, it was found that the quality of the lower surface could be quickly and accurately evaluated by the cooling time of the molten pool during the processing of the lower surface. This research can increase the understanding of the forming mechanism of the lower surface and has certain guiding significance for the process optimization of the lower surface.

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Numerical Simulation of Moving Heat Flux during Selective Laser Melting of AlSi25 Alloy Powder

Metals ◽

10.3390/met10070877 ◽

2020 ◽

Vol 10 (7) ◽

pp. 877

Author(s):

Cong Ma ◽

Xianshun Wei ◽

Biao Yan ◽

Pengfei Yan

Keyword(s):

Numerical Simulation ◽

Selective Laser Melting ◽

Process Parameters ◽

Molten Pool ◽

Laser Power ◽

Scanning Speed ◽

Powder Layer ◽

Maximum Temperature ◽

Three Dimensional Model ◽

Laser Melting

A single-layer three-dimensional model was created to simulate multi-channel scanning of AlSi25 powder in selective laser melting (SLM) by the finite element method. Thermal behaviors of laser power and scanning speed in the procedure of SLM AlSi25 powder were studied. With the increase of laser power, the maximum temperature, size and cooling rate of the molten pool increase, while the scanning speed decreases. For an expected SLM process, a perfect molten pool can be generated using process parameters of laser power of 180 W and a scanning speed of 200 mm/s. The pool is greater than the width of the scanning interval, the depth of the molten pool is close to scan powder layer thickness, the temperature of the molten pool is higher than the melting point temperature of the powder and the parameters of the width and depth are the highest. To confirm the accuracy of the simulation results of forecasting excellent process parameters, the SLM experiment of forming AlSi25 powder was carried out. The surface morphology of the printed sample is intact without holes and defects, and a satisfactory metallurgical bond between adjacent scanning channels and adjacent scanning layers was achieved. Therefore, the development of numerical simulation in this paper provides an effective method to obtain the best process parameters, which can be used as a choice to further improve SLM process parameters. In the future, metallographic technology can also be implemented to obtain the width-to-depth ratio of the SLM sample molten pool, enhancing the connection between experiment and theory.

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Heat transfer and fluid flow of molten pool during selective laser melting of AlSi10Mg powder: Simulation and experiment

Journal of Manufacturing Processes ◽

10.1016/j.jmapro.2017.02.009 ◽

2017 ◽

Vol 26 ◽

pp. 280-289 ◽

Cited By ~ 31

Author(s):

Xueping Ding ◽

Linzhi Wang

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Selective Laser Melting ◽

Molten Pool ◽

Laser Melting ◽

Simulation And Experiment

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Effects of the Processing Parameters on the Forming Quality of Stainless Steel Parts by Selective Laser Melting

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.3668 ◽

2011 ◽

Vol 189-193 ◽

pp. 3668-3671 ◽

Cited By ~ 5

Author(s):

Qing Song Wei ◽

Xiao Zhao ◽

Li Wang ◽

Rui Di Li ◽

Jie Liu ◽

...

Keyword(s):

Layer Thickness ◽

Selective Laser Melting ◽

Molten Pool ◽

Laser Power ◽

Single Layer ◽

Scanning Speed ◽

Processing Parameters ◽

Powder Layer ◽

Laser Melting

Selective Laser Melting (SLM) can produce high-performance metal parts with complex structures. However, it’s difficult to control the processing parameters, because many factors involves. From the perspective of the molten pool, the study focuses on the effects of processing parameters, including scanning speed, laser power, scanning space, layer thickness, and scanning strategies, on the surface quality, the balling effect, the density of SLM parts, by conducting experiments of single track, single layer and block forming. The results show that the quality of the molten pool is affected by laser power and scanning speed. Scanning drove in the strategy of “jumping and turning”，a smooth surface and a less balling effect will be obtained. The thicker the powder layer is, the lower density will be obtained. The optimal parameters from series of experiments are: laser power of 98W; scanning speed of 90mm/s; scanning space of 0.07mm; layer thickness of 0.1mm; and scanning strategy of “jumping and turning”.

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