Comparison of microstructure and mechanical properties of 316L austenitic steel processed by selective laser melting with hot-isostatic pressed and cast material

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2016-12, Vol.678, p.365-376
• Main Authors: Röttger, Arne, Geenen, Karina, Windmann, Matthias, Binner, Florian, Theisen, Werner
• Format: Article
• Language: English
• Subjects: Accumulation; Additive manufacturing; Austenitic stainless steels; Austenitic steel; Heat resistant steels; Hot-isostatic pressing; Laser beam melting; Materials selection; Mechanical properties; Microstructure; Porosity; Selective laser melting; Structural steels
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2016.10.012

Besides the chemical composition, the manufacturing route primarily determines a material's properties. In this work, the influence of the manufacturing process of the 316L grade austenitic steel on the microstructure and the resulting material properties were investigated. Thus, the microstructure and mechanical properties of cast and solution annealed, as well as steel powder densified by hot-isostatic pressing (HIP), selective laser melting (SLM) and SLM+HIP, were compared. A SLM parameter study illustrates that the porosity of SLM-densified specimens can be reduced with direction of a higher exposure time and a smaller point distance. With an additional treatment by HIP, the porosity scarcely changes, while cracks are reduced. The mechanical properties were investigated depending on the manufacturing process, and the influence of the sample build up by SLM was examined. High mechanical values have been obtained; in particular, the yield strength in the SLM-densified condition is much higher than in cast or HIP condition, as a result of the smaller grain size.