Adaptive Control of Additive Manufacturing Parameters in Pulsed Laser-Based Directed Energy Deposition of Super Duplex Stainless Steel: Hybrid Taguchi-Grey Relational Approach

Abstract Process parameters determine the quality characteristics of additively manufactured (AMed) parts. During Laser-based Directed Energy Deposition (DED-LB), an elaborated parametric analysis is required to control the materials’ behaviour precisely. This work deals with the effect of process parameters on process stability in terms of consistent melt pool geometrical features, such as aspect ratio of the bead and dilution, formation of pores, and ductility of super duplex stainless steel (SDSS) during pulsed laser and powder DED-LB. Independent variables including laser power, deposition speed, pulse frequency, and flow rate of the shielding gas were selected as controlling factors to deposit single tracks and plates of SDSS. Experiments have been designed and conducted according to L16 orthogonal array of Taguchi methodology. Relative density was estimated using Archimedes method. Ductility was estimated by tensile testing of the builds. For geometrical evaluation, phase characterization, and microstructural assessment, specimens were subjected to optical and Scanning Electron Microscopies, and Electron Backscattered Diffraction. Overall results were interpreted and explained using the Taguchi approach and analysis of signal-to-noise ratio. Single objective parameter-property relationships were achieved and discussed. Conclusive parametric remarks under the multi-attribute optimization were derived using weighted Grey Relational Analysis. A desirable parametric combination was extracted, and the associated quality responses were verified by the satisfying confirmatory deposition. The key role of parameters on the process stability, microstructure, and mechanical behaviour was further discussed. This work offers a practical solution to the multi-response optimization problems that can be used in AM and surface treatment of SDSS. Graphical Abstract