Study of the Influence of Main Parameters of the Selective Laser Melting Process on the Porosity of Aluminum Alloy RS-300 Samples

To date, the technology of selective laser melting has established itself as a method for manufacturing parts of complex shapes from metals and alloys. Aluminum and its alloys are widely used in aviation, space and other industries. The article presents the study of the influence of the main parameters of the process of selective laser melting on the porosity of samples made of Russian-made aluminum alloy RS-300. Samples were prepared using an SLP-250 setup and a multidirectional strategy for scanning with laser radiation the powder layer. Before the experiments, the granulometric, morphological and chemical analysis of the powder was performed. As a result of the experiments, samples with a density of more than 99.8% were obtained. The porosity of the samples was evaluated using a metrological computer tomograph. Pores of round and irregular shape were observed in the samples. Round pores were mainly formed due to evaporation processes and the presence of hollow powder particles. The formation of irregularly shaped pores is associated with insufficient specific energy of the growth mode, which mainly depends on the distance between scanning lines, scanning speed, and laser radiation power. To assess the microstructure of the samples, polished specimens were prepared, on which two types of microstructure were clearly observed. The first type was a fine microstructure in the center of the melt pool, and the second one was a coarse microstructure at the boundary of the melt pool. The occurrence of irregularly shaped pores can be leveled by selecting optimal growing conditions and strict adherence to the technological process.

References

[1] ASTM standard B213-13. Standard test methods for flow rate of metal powders using the hall flowmeter funnel. ASTM, 2013. 4 p.

[2] Grigor’yants A.G., Kolchanov D.S., Drenin A.A. et al. Influence of the main parameters of selective laser melting on stability of single track formation when ‘growing’ parts from copper alloys. Izvestiya vysshikh uchebnykh zavedeniy. Mashinostroenie [BMSTU Journal of Mechanical Engineering], 2019, no. 6, pp. 20–29, doi: http://dx.doi.org/10.18698/0536-1044-2019-6-20-29 (in Russ.).

[3] Martin J.H., Yahata B.D., Hundley J.M. et al. 3D printing of high-strength aluminium alloys. Nature, 2017, vol. 549, no. 7672, pp. 365–369, doi: https://doi.org/10.1038/nature23894

[4] Liu R., Wang Z., Sparks T. et al. Aerospace applications of laser additive manufacturing. In: Laser additive manufacturing. Woodhead Publ., 2017, pp. 351–371.

[5] Grigor’yants A.G., Kolchanov D.S., Drenin A.A. et al. Study of mechanical properties of samples from heat-resistant copper BrKh 0.8 alloy obtained by selective laser melting. Tsvetnye metally, 2021, no. 4, pp. 66–70. https://doi.org/10.17580/tsm.2021.04.11 (in Russ.).

[6] Ziri S., Hor A., Mabru C. Effect of powder size and processing parameters on surface, density and mechanical properties of 316L elaborated by Laser Powder Bed Fusion. ESAFORM, 2021, doi: https://doi.org/10.25518/esaform21.1563

[7] Jaber H., Kovacs T., János K. Investigating the impact of a selective laser melting process on Ti6Al4V alloy hybrid powders with spherical and irregular shapes. Adv. Mater. Process. Technol., 2020, doi: https://doi.org/10.1080/2374068X.2020.1829960

[8] Jiang J., Ma Y. Path planning strategies to optimize accuracy, quality, build time and material use in additive manufacturing: a review. Micromachines, 2020, vol. 11, no. 7, art. 633, doi: https://doi.org/10.3390/mi11070633

[9] Diegel O., Nordin A., Motte D. A practical guide to design for additive manufacturing. Springer, 2020. 236 p.

[10] Sun S., Zheng L., Liu Y. et al. Characterization of Al–Fe–V–Si heat-resistant aluminum alloy components fabricated by selective laser melting. J. Mater. Res., 2015, vol. 30, no. 10, pp. 1661–1669, doi: https://doi.org/10.1557/jmr.2015.110

[11] Galy C., Le Guen E., Lacoste E. et al. Main defects observed in aluminum alloy parts produced by SLM: from causes to consequences. Addit. Manuf., 2018, vol. 22, pp. 165–175, doi: https://doi.org/10.1016/j.addma.2018.05.005

[12] Grigor’yants A.G., ed. Lazernye additivnye tekhnologii v mashinostroenii [Laser additive technologies in machine design]. Moscow, Bauman MSTU Publ., 2018. 280 p. (In Russ.).

[13] Zhang C., Bao Y., Zhu H. et al. A comparison between laser and TIG welding of selective laser melted AlSi10Mg. Opt. Laser Technol., 2019, vol. 120, art. 105696, doi: https://doi.org/10.1016/j.optlastec.2019.105696

[14] Drenin A.A., Denezhkin A.O., Simonov A.P. Features of microstructure formation in products obtained by the technology of selective laser melting from copper alloys. Politekhnicheskiy molodezhnyy zhurnal [Politechnical Student Journal], 2019, no. 1, doi: http://dx.doi.org/10.18698/2541-8009-2019-11-547 (in Russ.

[15] Fiedler T., Dörries K., Rösler J. Selective laser melting of Al and AlSi10Mg: parameter study and creep experiments. Prog. Addit. Manuf., 2021, https://doi.org/10.1007/s40964-021-00248-5