A wide window of processing parameters for Laser-Powder Bed Fusion (L-PBF) processing of 316L stainless steel was identified based on our research to provide flexible solutions in priting parts of complex geometry. This project aimed at tailoring the microstructure to increase part performance and functionality. At the same time, high productivity process parameters are applied on areas where high performance is not required.
The printing parameters are tuned to according to the geometry and requirements of the part. A lower input energy is chosen for overhanging structures, a high productivity parameter set with increased layer thickness is chosen for traight sections with no strict requirement on properties, an optimized parameter set is applied to sections of part with strict requirement. The building process is monitored by a state-of-the-art Optical Tomography (OT) monitoring system.(a) Y-Z cross-section of the part showing melt pool intensities recorded by OT. (b) Sectional views at chosen locations showing varied heat input by tailoring printing parammeters.
The OT monitoring system takes an image of the build area per layer of deposition, and the grey value in each pixel of the image can be viewed as the radiation intensity locally, and therefore indicative of the melt pool intensity/temperature. The tailored processing parameters generate varied OT signals. The OT data can help the L-PBF users to gain a thorough understanding of how microstructure and texture development during the L-PBF as a function of printing parameters. In the future, monitoring systems will be an efficient way to control the process for high process robustness and repeatibility.
Researchers: Alex Leicht, Lars Hammar and Marie Fischer, Chalmers
Industry partner: AlfaLaval
Additive process used: L-PBF
Part size: 60 mm x 60 mm x 270 mm