Correlated high throughput nanoindentation mapping and microstructural characterization of wire and arc additively manufactured 2205 duplex stainless steel

Welding in the World https://doi.org/10.1007/s40194-024-01795-5 RESEARCH PAPER Correlated high throughput nanoindentation mapping and microstructural characterization of wire and arc additively manufactured 2205 duplex stainless steel Antoine Queguineur1,2 · Rahul Cherukuri3 · Aloshious Lambai3 Gaurav Mohanty3 · Jean‑Yves Hascoët2 · Iñigo Flores Ituarte1 · Manasi Sameer Dalal3 · Pasi Peura3 · Received: 29 June 2023 / Accepted: 24 May 2024 © The Author(s) 2024 Abstract Duplex stainless steels (DSS) in wire and arc additive manufacturing (WAAM) have attracted significant research attention due to their mechanical properties and corrosion resistance. This study uses conventional and nanomechanical testing methods to compare the mechanical and microstructural behaviors at macroscopic and microscopic length scales. Macro hardness (HV10) testing yielded 259 and 249 in low and high heat input (HI) samples, respectively, while ferrite content averaged 52.7 and 48.5%. However, these results fail to provide conclusive insight into the potential influence of microstructural variations at the macroscopic level, likely due to the composite response of the material. To overcome this limitation, the mechanical response of the DSS samples is assessed at the grain level via high throughput nanoindentation mapping with image processing to track the location of each indent. This approach enabled differentiating the indents landing on ferrite and austenite phases as well as those landing on the interfaces. The results showed that the austenite phase had higher hardness (4.30 and 4.35 GPa) than the ferrite phase (3.89 GPa and 4.03 GPa) for high and low HI samples, respectively. The observed differences in hardness between the phases can be attributed to higher nitrogen content in the austenitic phase. Keywords Additive manufacturing · Direct energy deposition · Nanoindentation mapping · Duplex stainless steel · WAAM 1 Introduction Duplex stainless steel (DSS) plays a vital role in various industries offering excellent mechanical strength and corrosion resistance. It is widely used in corrosive environments, Antoine Queguineur and Rahul Cherukuri contributed equally to this work. Recommended for publication by Commission I—Additive Manufacturing, Surfacing, and Thermal Cutting. * Antoine Queguineur 1 Automation Technology and Mechanical Engineering, Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 6, 33014 Tampere, Finland 2 GeM ‑ UMR CNRS 6183, Ecole Centrale de Nantes, 1 Rue de La Noé, 44321 Nantes, France 3 Materials Science and Environmental Engineering, Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 6, 33014 Tampere, Finland such as petrochemical industries, mining, transport, and the energy sector [1]. DSS is reasonably resistant against pitting and chloride corrosion [2] and typically consists of twophase microstructure at room temperature with nearly equal volume fractions of ferrite and austenite phases [3]. Solidification in welding of DSS results in the formation of ferrite dendrites. The austenite nucleates between 1300 and 800 °C at the grain boundaries (GB), followed by the formation of Widmanstätten austenite (WA) and intragranular austenite at lower temperatures. Conventional manufacturing techniques of DSS show that the formation of secondary phases deteriorate the overall ductility of the material [4]. Under certain conditions, other precipitations can form as well. These precipitates are both intergranular and intragranular and correlate well with local enrichment and saturation of elements such as Cr and N. The presence of these precipitates reduces the achievable toughness and can affect the corrosion resistance. An effective mitigation strategy against the formation of such detrimental secondary phases is to rigorously control the microstructure by adjusting the heat input during deposition. Vol.:(0123456789) Welding in the World Additive manufacturing (AM) (aka. 3D printing) enables disruptive workflows for integrated digital design and manufacturing. It has the potential to streamline supply chains [7, 8] and promotes more sustainable manufacturing models [9] based on on-demand and near-demand tailored production [10]. Direct energy deposition (DED) and, specifically, wire and arc additive manufacturing (WAAM), are exceptionally well positioned to transform the manufacturing of largescale metallic structural components. However, WAAM process creates high residual stresses [11], high dislocation densities, segregation of elements, and anisotropic structure in the build direction due to layer-by-layer manufacturing [12]. Extending AM-produced load-bearing parts for largescale industrial applications requires a deeper understanding of the correlation between the process-related attributes and thermal history during the build process (i.e., energy input, wire-feed rate, travel speed, interpass temperature, and deposition strategies) with the resulting microstructure and mechanical performance. Such studies will contribute towards developing a deeper understanding of the microstructure and mechanical properties to potentially tailor the performance of manufactured parts. Considering the challenges posed by structural components in WAAM, it is essential to explore the application of DSS within the context of AM. Recent research on additive manufacturing of DSS highlights significant variation in the ratio between ferrite and austenite [13]. While higher ferrite content improves the overall mechanical strength, it has been reported to negatively affect toughness and ductility [3]. Keeping a 1:1 ratio between ferrite and austenite will help in maintaining a compromise between these characteristics. Likewise, in WAAM processing of DSS, the formation of nitrides and carbides can potentially affect the mechanical and corrosion properties. The layer-by-layer nature of AM technologies, with multiple thermal cycles, and complex path planning strategies create unique heterogeneous structure in the printed part. Therefore, the resulting microstructures of DSS and defect formation differ from other conventional manufacturing processes, such as forging and casting [14]. AM generates multi-scale defects, similar to welding methods. Traditional methods for characterizing DSS involve metallographic examination associated with mechanical testing at macro-scale and micro-to-macrohardness testing. Given the stochastic nature of the location of the defects, a presence of indications can hinder the accuracy/effectiveness of the mechanical results [15]. At micro-level, novel atomistic simulation techniques reveal the influence of imperfections at the crystal level, possibly affecting the nanoindentation experiments [16]. Indenting at the grain level on large surface randomly involves grains-boundaries and other microstructural features possibly interacting with the measurements. In the industrial context, ma (...truncated)