Enhancing microstructural analysis: best practices for preparing duplex stainless steel welds and additive manufacturing deposits

Abstract The growing use of duplex stainless steels (DSSs) has spurred extensive research and development, particularly concerning weldability challenges. The increasing interest in additive manufacturing (AM) using directed energy deposition (DED) has further highlighted the need for precise sample preparation to ensure accurate microstructural characterization. This paper consolidates best practices for preparing samples to effectively reveal microstructures and secondary phases in DSSs. By optimizing polishing techniques and etching methods, the work provides guidelines for distinguishing ferrite and austenite across the base material, heat-affected zone (HAZ), and weld metal, while also enabling the detection of intermetallic phases and discrete secondary precipitates. Examples of typical deviations, etching phenomena, and potential pitfalls are also provided. The preparation strategies presented are tailored to support subsequent analysis using light optical microscopy (LOM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM).