Microstructural evolution and wear characteristics of thin-walled Inconel 617 structures fabricated by wire arc additive manufacturing

This study investigates the microstructural evolution and dry sliding wear behaviour of Inconel 617 (IN617) components fabricated by Wire Arc Additive Manufacturing (WAAM). Microstructural characterisation revealed a mixed morphology of equiaxed and columnar dendrites in the horizontal orientation, whereas the vertical orientation was dominated by columnar dendrites. Noticeable elemental segregation was observed in interdendritic regions. Energy-dispersive spectroscopy (EDS) confirmed the formation of Mo–Cr-rich carbides (M6C/M23C6) and Ti(C,N) precipitates, resulting from the limited solubility of Ti and Mo in the γ-matrix. Vickers microhardness measurements showed an average hardness of 272 ± 4 HV0.5 in the horizontal direction, higher than 260 ± 7 HV0.5 in the vertical direction, attributed to the mixed microstructure and uniform precipitate distribution. Dry sliding wear tests were performed using a pin-on-disc configuration under loads of 10 and 20 N. At 10 N, horizontal specimens exhibited a 17% lower wear rate than vertical specimens. Increasing the load to 20 N significantly increased wear in both orientations, with wear rates rising by about 2.6 and 2.7 times in the vertical and horizontal direction, respectively. Surface analyses indicated abrasive and mild adhesive wear at lower loads, while higher loads promoted severe delamination and adhesive wear, particularly in vertical specimens.