Speaker
Description
Metal Additive Manufacturing and more specifically Laser Powder bed Fusion (L-PBF) is combining very unique process conditions resulting in fascinating microstructures. The very high energy density of the laser leads to very high melt pool temperatures and high cooling rates causing ultrafine and often supersaturated and metastable unique microstructures. The additive nature of the process adds an additional dimension that will greatly determine the directionality of the physical phenomena such as solidification and grain growth. Given the digital control of the laser path and its settings, nowadays even a localized control is possible enabling location specific microstructures and further customizable for different locations within a single part.
However, because the material and the product shape are created simultaneously and that often complex shapes are printed, process conditions vary depending on the local geometric complexity and size of the part. These changes in process conditions can alter the physical behavior of the meltpool leading to various defects such as porosities. Also the dimensions of the printed parts can be effected by these local differences in process conditions through for example a change in shrinkage behavior and/or inhomogeneity in the residual stresses build up. Proper CAD/CAM file preparation of both the shape and orientation of the parts as well as the specific L-PBF process parameters is therefore of paramount importance to minimize (unintended) local process variations and increase the production‘s success rate. In addition to the file preparation, proper heat treatments needs to be selected to first of all relieve the residual stresses and depending on the constitution of the alloy also further strengthen or soften the material.
Finally, from economic point of view, further optimization of the L-PBF process and post treatment parameters towards low run times is often needed. This gives an interesting balancing exercise between economics, part’s shape and dimension and microstructure optimization.