Lecture
WEB L-PBF-Microstructures of Steel Alloys and Nickel Base Alloys
Wednesday (23.09.2020) 17:35 - 17:50 S: Structural Materials 1 Part of:In this work, different cast alloys (austenitic steel 1.4408, duplex steel 1.4517, nickel base alloy 6.4856 and nickel-base-copper alloy 6.4356) were gas atomized and printed in the L-PBF-process. Their microstructures were investigated and compared using two different scanning strategies and heat treatments. Calphad and Scheil-Gulliver numeric simulations for non-equilibrium solidification will be presented. Equiaxed, columnar and epitaxial structures and precipitates were characterized with various analytical and microscopic methods.
Precipitates, melt lines and other microstructural phases under the following process stages were analyzed:
• Cast material
• Powder particles for L-PBF
• LPBF microstructure
• LPBF microstructure after post heat treatment
• Tensile test samples
Correlations between microstructure and tensile properties were established. Although the strength was only mildly affected by varying the scanning parameters, the ductility was significantly influenced. Post-heat treatments had different effects on the ductility. Compared to the cast material, the additive samples achieved an improvement in mechanical properties in all cases.
Methods of investigation: REM, EDS, EBSD, LOM, tensile tests, Calphad simulation, Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), inert gas fusion (IGF).
