Additive Manufacturing of Inconel 625 Using the Laser-Based Directed Energy Deposition (DED-LB) Technique

Abstract

Laser-Based Directed Energy Deposition (DED-LB) is a leading additive manufacturing (AM) technique used to produce superalloys. Inconel 625 (IN625), a nickel-based superalloy, is renowned for its exceptional mechanical strength and resistance to oxidation. The AM of Inconel 625 using LDED-LB is an emerging technology that requires extensive research. Further investigations are essential to fully exploit the capabilities of LDED-LB for fabricating IN625 parts and to ensure their reliable application in demanding industries such as aerospace, automotive, and energy. In this study, 3D-printed IN625 specimens were produced using a 1000 W continuous-wave fiber laser. The samples, measuring 30 mm × 10 mm and consisting of five layers, were printed on an AISI 4130 steel substrate. The microstructure and microhardness of the samples were evaluated using an optical microscope (OM), a scanning electron microscope (SEM), and a microhardness testing device. The results indicate that the microstructure of IN625 consists of both columnar and equiaxed dendritic grains. As the distance from the substrate increases, the microstructure transitions from columnar dendrites -most noticeable along the secondary dendrite arms- towards a predominantly equiaxed structure. Additionally, the average microhardness value varies between 257 HV and 323 HV at different points of the sample, with microhardness generally decreasing as the distance from the substrate increases.