Surface integrity enhancement through vibration-assisted ball burnishing of maraging steel produced by selective laser melting

Abstract

This study investigates the effects of post-processing techniques on the surface roughness and the mechanical behavior of additive manufactured (AM) components. Post-processing has been identified as essential for applications where surface integrity directly impacts component performance. Specifically, it includes milling (M), vibration-assisted ball burnishing (VABB), and their combined application as finishing techniques. Utilizing a Taguchi L27 design, the study identifies the most significant parameters influencing the VABB process for two distinct surface conditions: AM + M + VABB and AM + VABB. Results indicate that for the AM + M + VABB condition, the burnishing force (Fb) and the lateral offset (LO) significantly affect surface roughness, with increased values leading to rougher surfaces. Conversely, for the AM + VABB condition, Fb and the number of passes (Np) are the most influential parameters, highlighting the importance of force and repetition in achieving lower roughness values. The combined post-processing method of AM + M + VABB yielded the most substantial surface improvement, achieving an Sq (root mean square height) value of 0.23 μm, which represents a 98 % reduction in roughness compared to the initial AM condition. Both post-processing methods produced Gaussian material distributions. Subsurface analyses revealed plastic deformation, grain refinement, surface hardening, and residual stress, with the AM + M + VABB condition exhibiting the highest degree of plastic deformation. These findings demonstrate the effectiveness of combining milling and VABB to optimize the surface roughness and mechanical properties of AM components, establishing a viable post-processing route for advanced manufacturing applications, highlighting the potential of VABB as an alternative to traditional finishing methods.