Selective laser melting (SLM) of AISI 316L—impact of laser power, layer thickness, and hatch spacing on roughness, density, and microhardness at constant input energy density

• Published in: International journal of advanced manufacturing technology Vol. 108; no. 5-6; pp. 1551 - 1562
• Main Authors: Greco, Sebastian, Gutzeit, Kevin, Hotz, Hendrik, Kirsch, Benjamin, Aurich, Jan C.
• Format: Journal Article
• Language: English
• Published: London Springer London 01-05-2020; Springer Nature B.V
• Subjects: Additive manufacturing; Austenitic stainless steels; CAE) and Design; Computer-Aided Engineering (CAD; Engineering; Flux density; Industrial and Production Engineering; Laser beam melting; Lasers; Mechanical Engineering; Media Management; Microhardness; Original Article; Process parameters; Rapid prototyping; Roughness; Scanning; Thickness; Workpieces; Additive manufacturing; Selective laser melting; Relative density; Microhardness; Input energy density
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-020-05510-8

In selective laser melting (SLM) the variation of process parameters significantly impacts the resulting workpiece characteristics. In this study, AISI 316L was manufactured by SLM with varying laser power, layer thickness, and hatch spacing. Contrary to most studies, the input energy density was kept constant for all variations by adjusting the scanning speed. The varied parameters were evaluated at two different input energy densities. The investigations reveal that a constant energy density with varying laser parameters results into considerable differences of the workpieces’ roughness, density, and microhardness. The density and the microhardness of the manufactured components can be improved by selecting appropriate parameters of the laser power, the layer thickness, and the hatch spacing. For this reason, the input energy density alone is no indicator for the resulting workpiece characteristics, but rather the ratio of scanning speed, layer thickness, or hatch spacing to laser power. Furthermore, it was found that the microhardness of an additively manufactured material correlates with its relative density. In the parameter study presented in this paper, relative densities of the additively manufactured workpieces of up to 99.9% were achieved.