It has been demonstrated that a monomolecular surface film with semiconducting characteristics forms on an austenitic, corrosion- and heat-resistant chromium–nickel steel with 0.10 wt.% C, 20 wt.% Cr, 9 wt.% Ni, and 6 wt.% Mn (10Kh20N9G6), microalloyed with yttrium, in aqueous 1 M H2SO4. This passive layer exhibits semiconducting behavior, as confirmed by electrochemical impedance and capacitance measurements. For the first time, key electronic parameters, including the flat-band potential, the thickness of the semiconductor layer, and the Fermi energy, have been determined from experimental Mott–Schottky plots obtained for the interphase boundary between the yttrium-microalloyed austenitic Cr–Ni steel (10Kh20N9G6) and aqueous 1 M H2SO4. The results reveal a systematic shift in the flat-band potential toward more negative values with increasing yttrium content in the alloy, indicating a modification of the electronic structure of the passive film. Simultaneously, a decrease in the Fermi energy is observed, suggesting an increase in the work function of the metal surface due to the presence of yttrium. These findings contribute to a deeper understanding of passivation mechanisms in yttrium-containing stainless steels. The formation of a semiconducting passive film is essential for enhancing the electrochemical stability of stainless steels, and the role of rare-earth microalloying elements, such as yttrium, in this process is of both fundamental and practical interest.

The paper presents a comparative experimental study of heat-transfer behavior in three alloys considered candidate materials for nuclear reactors: the austenitic stainless steel 316L, Zircaloy-4 (currently used in CANDU reactors), and an ODS alloy with a ferritic matrix. The investigation was conducted across five temperature intervals, each sample being subjected to a thermal shock through short-term overheating to the upper limit of its respective interval. The variation of thermal diffusivity in the three alloys was determined as a function of both measurement temperature and applied thermal shock, and trends in heat-transfer behavior were compared across the five temperature ranges. The experimental results show that up to 400 °C, Zircaloy-4 exhibits the highest thermal diffusivity, followed by the ODS alloy, with the lowest values measured for 316L steel. At approximately 450 °C, the ratio between 316L and the ODS alloy reverses. Beyond this point, increasing the temperature up to 900 °C is accompanied by a continuous rise in thermal diffusivity for both 316L stainless steel and Zircaloy-4. In contrast, for the ODS steel, increasing temperature leads to a continuous decrease in thermal diffusivity, reaching a minimum near the Curie point. The novelty of the study lies in the comparative assessment of the influence of temperature on the heat-transfer process in three alloys relevant to nuclear energy, covering the operating temperature ranges of CANDU and ALFRED reactors, as well as potential accidental overheating up to 900 °C. A particular feature of the work is the prior application of a short-duration overheating step produced using solar energy. The results are relevant not only for nuclear reactors but also for other high-temperature applications in corrosive environments.

Abstract Austenitic stainless steels produced by powder metallurgy (PM) reportedly exhibit higher resistance to hydrogen embrittlement than conventionally produced grades. This improved resistance is commonly attributed to their lower tendency for martensitic phase transformation. One previously unaddressed factor that may contribute to this behavior is the difference in chemical homogeneity between PM and conventionally manufactured parts. The present work investigates chemical homogeneity as a factor influencing the phase stability of PM-produced metastable austenitic steel X2CrNi18-9. Slow strain rate tensile tests were conducted at − 50 °C on cast and hot-formed (wrought) specimens, as well as on PM conditions produced by hot isostatic pressing and PBF-LB/M. Simultaneous electron backscatter diffraction and energy-dispersive X-ray spectrometry of the wrought material reveal band-like Ni and Cr segregations elongated along the deformation direction. Ni-depleted regions were identified as preferential sites for martensite formation, which propagates in a block-like manner into regions of higher austenite stability. In contrast, the PM conditions exhibit higher chemical homogeneity, resulting in an overall lower fraction of deformation-induced martensite. This study demonstrates that chemical homogeneity is a critical parameter in the assessment of hydrogen embrittlement resistance of austenitic stainless steels and should be considered alongside other influencing factors.

The stainless-steel phase of austenite, ferrite, and duplex was affected by the high temperature corrosion. So, the study of corrosion behavior in high temperatures at 700 °C is important because it is connected to life and maintenance. Various stainless steels (AISI no. 409 L, 430 L, 304L, 316L, 2205, 2507) are used to identify the most suitable material for high-temperature SOFC applications. The study was checked to surface, microstructure, and corrosion behavior after corrosion at 700 °C during 120 h. The surface and microstructure are checked using FE-SEM and XRD. The electrochemical behavior and corrosion behavior are checked for open circuit potential, electrochemical impedance spectroscopy, and potentiodynamic polarization test by a potentiostat. The potentiodynamic polarization results revealed that the pitting potential (Epit) varied significantly depending on the material, with values of 0.21 V for AISI 304L and 1.14 V for AISI 2507. The breakdown behavior of the passive film exhibited material-dependent characteristics, which were found to be consistent with the observed trends in high-temperature corrosion.

Phase transformation and radiation-induced hardening in austenitic stainless steels at cryogenic temperatures

Phase stability, microstructural evolution, and corrosion behavior of GTAW-welded AISI 316 L austenitic stainless steel

Effect of nitrogen on grain refinement strengthening in austenitic stainless steel at 77 K

Intergranular creep damage in an austenitic stainless steel: A coupled phase field-crystal plasticity study

Elevated temperature material properties of a new nickel-free austenitic stainless steel

Influence of chloride ion concentration on the corrosion behavior of 304 austenitic stainless steel in sulfuric acid

Synergistic influence of laser scanning strategies and heat treatments on the microstructure-mechanical property relationship of laser directed energy deposited austenitic stainless steel 304

Synergistic enhancement of the corrosion resistance of N08926 super austenitic stainless steel by combining laser cladding and electropolishing

Microstructural evolution and mechanical behavior of Ni-saving/N-enhancing austenitic stainless steel processed by strain strengthening for pressure vessel applications

Process induced plastic deformation in additively manufactured 316L austenitic stainless steel

Exploring the effect of W on the W-containing Laves precipitates and internal oxidation mechanism of cobalt-containing austenitic stainless steel

Role of Deformation Mechanism Mismatch on Hydrogen embrittlement of Welded Austenitic Stainless Steel

Radiation swelling of Ti-stabilized 15Cr-15Ni austenitic stainless steels with cold work levels of 15% – 25%

Precipitation behavior and mechanical properties of 16Cr−25Ni austenitic stainless steel weld metals with different Mo content during aging

Effects of hydrogen on nanoscale plasticity and creep in heat-treated LPBF 316L austenitic stainless steel

Introduction/purpose: Hydrogen embrittlement (HE) substantially decreases the mechanical properties of austenitic stainless steels, constraining their efficacy in diverse applications. This study examines the impact of electrolytic hydrogen charging on the mechanical characteristics and microstructure of AISI304 stainless steel, a commonly utilized grade. Methods: Tensile specimens measuring 8 mm in diameter were produced through machining and subjected to hydrogen loading electrolytically at different times in a glass chamber containing sulfuric acid (H 2SO 4 ) at 0.05M. The mechanical tests were conducted using a Karl Frank GMBH tensile testing universal machine, type 83431. The samples underwent microscopic analysis by means of optical microscopy (OM), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The experimental characterization involved producing cylindrical specimens which underwent heat treatments (austenization) ranging from quenching to tempering, followed by immersion in a cold heat treatment cycle at -196°C for 35 minutes. Hydrogen preloading was carried out through electrochemical hydrogen charged for different loading times in hours. Results: The results showed that the effects of hydrogen embrittlement (HE) on AISI304 stainless steel are characterized by a decrease in ductility, sometimes undergoing sudden embrittlement. This phenomenon is consistently recognized by other authors who have demonstrated a loss of ductility due to the martensitic transformation of austenite caused by deformation and hydrogen diffusion. Conclusion: Inclusions such as second-phase particles, carbide precipitates, inclusions of small, medium, or large size, interfaces, and interphases, can be considered inclusions. Their mechanical properties and hydrogen transport and segregation mechanisms differ from those of the matrix, particularly in martensitic structures. The observation of the optical dark area (ODA) and black spots indicates that hydrogen is concentrated either in the molecular form H 2 or combined with sulphur in the form of H2S.