Electron Beam Welding of Additively Manufactured Inconel 939 – Process Characteristics and Achievable Weld Quality

Additive manufacturing technologies such as the laser powder bed fusion provide significant potential for the fabrication of new and replacement parts for stationary gas turbines made of nickel superalloys such as Inconel 939. To enable integration of repaired components into existing assembly units and to overcome dimensional limitations, the additive manufacturing process chain must be expanded to include suitable joining techniques. This work therefore deals with the welding of Inconel 939. It compares cast sheets and sheets produced additively using laser powder bed fusion in terms of their behavior during electron beam welding. The investigation focuses on the achievable seam quality with regard to geometric irregularities and internal defects in the form of microcracks in the heat-affected zone. No differences in the formation of the seam shape between the additively manufactured material and the cast material were found when evaluating the welded samples. The highest quality level for beam-welded seams according to DIN EN ISO 13919-1 was achieved for both materials at a high welding speed of 20 mm/s. Regardless of the manufacturing method, both materials show an increase in crack susceptibility with increasing welding speed. Due to its microstructure the material from additive manufacturing has significantly fewer microcracks overall, which opens up potential for practical application.