Manufacturing of 2507 Superduplex Stainless Steel by Laser Powder-Directed Energy Deposition: process optimization and microstructure analyses

Abstract This paper presents a thorough manufacturability study of superduplex 2507 stainless steel (SDSS) produced by the Laser Powder-Directed Energy Deposition (LP-DED) process. First, experimental observations on single-track surface morphology and geometrical characteristics are described. Then, dimensional and porosity analyses of thin walls and bulk samples are presented and discussed in order to identify the optimal process parameter combinations, from a process point of view, for further characterizations to determine general properties of LP-DED-printed samples. Finally, the results obtained on a wrought steel of the same grade are finally compared to those of the printed material in terms of microstructure, texture and ferrite/austenite ratio. A set of meticulously chosen process parameters with regard to the process and the machine (nozzle size, maximum power deliverable) gives the optimal results for the as-built LP-DED material in terms of porosity and microstructure quality but with smaller grains (irrespective of the phase studied) and a higher proportion of ferrite (about 75 %).