Nickel-base superalloys, due to their excellent high temperature corrosion and creep resistance, are largely used in aerospace and land-based gas turbine engines. Alloys such as IN939, IN738 and MAR-M247 are required for components with high service temperature, and typically contain a high fraction of "gamma prime" strengthening phase. Unfortunately, their poor weldability is a challenge for production by additive manufacturing. The nature of layer-wise manufacturing, with fast cooling rates and heat cycling, can potentially form cracks through different mechanisms such as HAZ liquation, solidification and strain-age cracking. This study focuses on the effect of the DMLS process on defect formation within hard-to-weld superalloys and attempts to improve weldability through adjustment of critical process input factors. The process monitoring tool EOSTATE MeltPool was used to observe melt pool behaviour and detect locally overheated areas. Results indicate that it is possible to significantly improve processability and reduce cracking by using optimized parameters.
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