Lecture
WEB Correlation of different duplex steel microstructures produced by laser powder bed fusion to their static and fatigue properties
Wednesday (23.09.2020) 17:20 - 17:35 S: Structural Materials 1 Part of:Laser Powder Bed Fusion (LPBF) has become an attractive alternative to conventional processing routes over the past few years. While some alloys like the austenitic steel 316L are already processed in series production, duplex steels have received little attention so far. In this study, two duplex steels, X2CrNiMoN22-5-3 and X2CrNiMoN25-7-4, are produced by LPBF, their static and fatigue properties were determined and correlated to the underlying microstructure. The investigations include the influence of two post processing heat treatments solution annealing and hot isostatic pressing followed by solution annealing. The mechanical characterization comprises the methods tensile test, impact notch test, rotating bending test while the microstructure is investigated by means of light optical microscopy and X-ray diffraction. The ferritic microstructure in the as-built samples relates to a high yield and tensile strength but low ductility and fatigue strength. Both heat treatment routes attain the desired ferrite-austenite microstructure which significantly improves the ductility and the fatigue behavior while maintaining a good level of yield and tensile strength. The results indicate LPBF to be a promising alternative for the production of duplex steels in terms of mechanical properties.
