Functionality-Related Performance of Surface Microrelief Evaluation in Ultrasonically and Shot Peened Inconel 718 Alloy Manufactured by Laser Powder Bed Fusion Process

In this study, the effects of the ultrasonic shot peening, multi-pin ultrasonic impact peening, and shot peening on the 3D surface texture parameters and functionality-related properties of additively manufactured Inconel 718 material were analyzed and compared. Inconel 718 alloy parts were produced by a laser powder bed fusion (LPBF) additive manufacturing process with a build angle of 90 degrees using a stripe scanning strategy. The influence of severe surface plastic deformation techniques on surface morphology evolution and areal functional parameters/indices to analyze the wear and lubrication behavior was studied via confocal scanning microscopy. It was observed that the applied mechanical surface post-treatments decreased the average surface roughness parameters. The values of the area surface roughness parameters are the highest for shot peening and lowest for multi-pin ultrasonic impact peening. The results showed that the ultrasonic finishing post-treatments provided a decrease in the area surface roughness Sa parameters magnitudes by 3-6 times as compared to the LPBF-built parts. The formation of surface microrelief by peening techniques leads to improved functionality-related performance in the LPBF-fabricated superalloy parts.