Influence of gas atomization atmosphere on nitrogen content, phase stability, and hydrogen embrittlement of duplex stainless steel processed by additive manufacturing

• Grant number: 26/03937-3
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: July 01, 2026
• End date: June 30, 2029
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Piter Gargarella
• Grantee: Bruna Fernanda Batistão
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research grant: 20/06984-6 - Development of the additive manufacturing production chain of metal components, AP.NPOP

Abstract

The transition toward hydrogen-based energy systems poses significant challenges to the structural integrity of metallic materials exposed to hydrogen-containing environments under severe conditions. Duplex stainless steels are widely used in these contexts due to their combination of high mechanical strength and corrosion resistance, however, their duplex microstructure (ferrite/austenite) may render them susceptible to hydrogen embrittlement (HE), particularly when processed by additive manufacturing (AM). Laser Powder Bed Fusion (L-PBF) processing generates non-equilibrium microstructures characterized by a high ferrite fraction, elevated defect density, and local chemical heterogeneities, whose effects on hydrogen absorption and trapping mechanisms are not yet fully understood. This project proposes to investigate, in an integrated and multiscale manner, how the nitrogen content introduced into the atomized powder influences the microstructural evolution of duplex stainless steels processed by L-PBF and how this evolution affects HE susceptibility. Duplex stainless steel 2205 powders will be produced by gas atomization under different atomization atmospheres (Ar and H2), processed by L-PBF, and subjected to controlled heat treatments. Characterization will involve advanced microstructural techniques, mechanical testing with and without electrochemical hydrogen charging, quantification of absorbed hydrogen, and evaluation of corrosion resistance after charging. Additionally, Atom Probe Tomography (APT) analyses, within the framework of a BEPE research stay, will allow investigation of the atomic-scale distribution of nitrogen and hydrogen and heterogeneities at ferrite/austenite interfaces. It is expected to establish correlations between powder composition, phase architecture, and performance under hydrogen, contributing to the development of microstructural design guidelines aimed at mitigating hydrogen embrittlement in components produced by AM. (AU)