Selective Laser Melting of Ni-based Superalloys: High Speed Imaging and Process Optimisation

Sammanfattning: Additive manufacturing is the process of joining or adding material to build an object from 3D model data. Selective Laser Melting (SLM) is an additive manufacturing technology that generates components layer by layer. Though it is already being used in the industry, some aspects are not very well understood. In this thesis, high speed imaging is used to gain new insights about the interaction of laser light with material. A number of parameter sets for high e ciency and good surface finish were found for a nickel based superalloy, HastelloyXTM. Three setups are discussed: single laser pulse interaction with powder, low speed SLM and high speed SLM. It was found, that in order to observe powder behaviour, a narrow bandwidth illumination source is necessary. The low speed SLM process was imaged clearly and revealed three stages of the process, i.e. powder redistribution, melting and drop incorporation. In contrast, the high speed process included vertical powder displacement. Influence of various process parameters is also discussed.