Tailoring and investigation of defined porosity properties in thin-walled 316L structures using laser-based powder bed fusion
Process engineering applications, which require a defined mass transport, call for thin-walled structures with a defined open porosity. Powder bed fusion by a laser beam (PBF-LB) is investigated as a potential manufacturing method using stainless steel 316L to produce such structures. The total porosity was determined by weighing and volume measurement. The influence of the process parameters laser power, scan speed and hatch distance on porosity was investigated by means of a design of experiments (DoE) approach using a central composite design (CCD). A statistically significant regression model was developed to allow a prediction of the porosity values within the design space. To determine the distribution and size of porous sections, computed tomography and a microscope in transmitted light mode were used as well. Permeability was also analyzed. Within the design space, a permeability coefficient of 2258.26 E−12 m2 was achieved with a maximum porosity value of 19.00%. With the help of the CT analysis, it was determined that for area laser energy densities between 0.625 and 0.744 J/mm2, the average pore size from 4728.57 to 9841.38 µm2 can be adapted.
KeywordsAdditive manufacturing Powder bed fusion 316L Porosity Thin walls
The authors extend their thanks to the German Research Foundation (DFG) for the funding of the projects AB 133/97-1 and HA 1283/11-1. This support has enabled the described investigations in the area of additive manufacturing, which have led to the results presented in this article.
- 1.Karageorgiou V, Kaplan D (2005) Porosity of 3D biomaterial scaffolds and osteogenesis. Biomaterials 26(27):5474–5491. https://doi.org/10.1016/j.biomaterials.2005.02.002 CrossRefGoogle Scholar
- 9.Yamada Y, Shimojima K, Sakaguchi Y et al (2000) Processing of cellular magnesium materials. Adv Eng Mater 2(4):184–187. https://doi.org/10.1002/(SICI)1527-2648(200004)2:4%3c184:AID-ADEM184%3e3.0.CO;2-W CrossRefGoogle Scholar
- 13.Stoffregen H, Fischer J, Siedelhofer C et al (2011) Selective laser melting of porous structures. In: Solid freeform fabrication symposium, Austin, Texas, 8–10 Aug. 2011, pp 680–695Google Scholar
- 14.Spierings AB, Wegener K, Levy G (2012) Designing material properties locally with additive manufacturing technology SLM. In: Proceedings solid freeform fabrication symposium, pp 447–455Google Scholar
- 24.Gong H (2013) Generation and detection of defects in metallic parts fabricated by selective laser melting and electron beam melting and their effects on mechanical properties. https://doi.org/10.18297/etd/515
- 29.Schaeffler AL (1949) Constitution diagram for stainless steel weld metal. Metal Prog 56:680Google Scholar
- 32.New York International Nickel Co., Inc. (1963) Corrosion resistance of the austenitic chromium–nickel stainless steels in chemical environments. New York International Nickel Co. Inc., New YorkGoogle Scholar
- 35.Ho ST, Hutmacher DW (2006) A comparison of micro CT with other techniques used in the characterization of scaffolds. Biomaterials 27(8):1362–1376. https://doi.org/10.1016/j.biomaterials.2005.08.035 CrossRefGoogle Scholar