Study of the surface roughness of a remanufactured bimetallic AISI 1045 and 316L SS part obtained by hybrid manufacturing (DED/HSM)

Directed energy deposition (DED) is an additive manufacturing process that produces remanufacturers and repairs metal parts and its unique characteristics enable the combination of materials with different properties and surface functionalization. However, DED alone does not always produce surfaces and dimensional quality suitable for most intended applications, thus requiring post-processing steps. Research on post-processing materials obtained by metal additive manufacturing has focused on non-conventional processes, primarily over flat surfaces. Little emphasis has been placed on surface characteristics, mainly when traditional operations are conducted on more intricate geometries. DED and machining can be combined in the same equipment, in what is called hybrid manufacturing (HM). This research work performs an example of remanufacturing using an HM process. An injection mold part, originally in AISI 1045, was remanufactured with AISI 316L stainless steel with the use of laser-based directed energy deposition (DED-LB) and high-speed machining (HSM) towards improving surface finishing and dimensional accuracy. The parameters and strategy employed by DED-LB obtained a material with no significant porosity, cracks, or microstructure defects. The stainless steel improved the corrosion resistance of the component; the resulting microstructure was similar to those obtained in similar works and hardness was slightly higher, enhancing the wear resistance. An analysis of surface roughness using Sa revealed different roughness values for the side and top areas with a strong dependency on both trajectory and semi-melted particles. The HSM process reduced the Sa value by approximately 90% with relatively short times in comparison to other surface finishing processes. The remanufacturing of components by DED-LB deposition of stainless steel onto carbon steels has opened a wide range of new applications, especially for complex 3D surfaces belonging to high-value components.