The effects of laser welding parameters on weldability and quality of the microstructure of additively manufactured Inconel 718-316L joints

Abstract

Additive manufacturing of metals is a way of producing high-quality end-use parts. Technical alloys, for example Inconel 718, can be used to obtain a lot of benefits for example wear, corrosion, and heat resistance. Laser welding of Inconel 718 is a standard process, but there is rather limited amount of information of welding of additively manufactured nickel superalloys to the additively manufactured stainless steel. The process parameters need to be considered in laser welding. Undesired microstructure can occur due to wrong heat input during the welding process. This study examines laser welding of additively manufactured Inconel 718-316L parts and the effects of the welding parameters to the quality of the weld by analysing microstructure from the heat affected zone. This is done to achieve better part quality more cost efficiently compared to traditionally produced parts and to optimize the welding parameters. It is not feasible to manufacture the full large structure with IN718 and AM could be used to manufacture just the functional parts of the assembly. Tests have shown that welding heat input and cooling time affect to the quality. Inconel 718 hardness decrease across the fused zone because of the mixing of different elements in the molten weld pool. Laser welding highlights cuboidal shaped niobium rich carbides throughout the material to the heat affected zone grain boundaries on Inconel side.