The application possibilities of austenitic stainless steels in high friction, abrasion, and sliding wear conditions are limited by their inadequate hardness and tribological characteristics. In order to improve these properties, the thermochemical treatment of their surface by plasma nitriding is suitable. This article is focused on the corrosion resistance of conventionally plasma-nitrided AISI 304 stainless steel (530 °C, 24 h) in 0.05 M and 0.5 M sodium chloride solutions at room temperature (20 ± 3 °C), tested by potentiodynamic polarization and electrochemical impedance spectroscopy. Optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy are used for nitrided layer characterization. The experiment results confirmed the plasma-nitrided layer formation of increased micro-hardness related to the presence of CrN chromium nitrides and higher surface roughness compared to the as-received state. Both of the performed independent electrochemical corrosion tests point to a significant reduction in corrosion resistance after the performed plasma nitriding, even in a solution with a very low chloride concentration (0.05 mol/L).
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http://dx.doi.org/10.3390/ma17174189 | DOI Listing |
Materials (Basel)
January 2025
Faculty of Engineering, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507, Hokkaido, Japan.
The addition of hydrogen to nitrogen facilitates the formation of nitride phases in the plasma nitriding processes of stainless steels, though it also induces the deterioration of their mechanical properties. This study presents a hydrogen-free plasma nitriding process for fabricating a nitrogen-expanded austenite phase (γ) on an AISI 316 stainless steel surface. The steel substrate was nitrided in N-Ar plasma with various gas compositions discharged by radio frequency (RF) and direct current (DC) modes.
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December 2024
School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China.
In this study, a novel Cu-bearing 304 stainless steel doped with 4.0 wt.% Cu (304-Cu SS) was developed, and the effects of nitrogen microalloying (304N-Cu SS) and heat treatment on mechanical, antibacterial, and corrosion properties were investigated.
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December 2024
Institute of Environmental Engineering, Wrocław University of Environmental and Life Sciences, pl. Grunwaldzki 24, 50-363 Wroclaw, Poland.
Austenitic stainless steels are used widely in many fields due to their good mechanical properties and high resistance to corrosion. This work focuses on the reconstruction of the passive film after scratching. The purpose of the study was to compare changes in the rate of passive layer reconstruction and to discuss the effect of both the type of material and its electrochemical treatment on the reconstruction of the passive layer for two types of stainless steel: 304 and 316.
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December 2024
Department of Production Engineering, Faculty of Mechanical and Energy Engineering, Koszalin University of Technology, Raclawicka 15-17, 75-620 Koszalin, Poland.
In this study, the relationships between the values of the parameters included in heat input (welding current, arc voltage and welding speed) and their effects on the size of the cross-sectional areas of welds in joints made of ferritic-austenitic stainless steel using the GMAW method were determined. An attempt was also made to determine to what extent it will be possible to predict the properties of fabricated welded joints using the functional relationship describing the effect of the value of heat input on the size of the cross-sectional area of welds. The analysis of the developed mathematical models shows their suitability for explaining (and predicting) the sizes of the cross-sectional areas of welded joints depending on the values of the input parameters of the welding process.
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December 2024
National Center for Materials Service Safety, University of Science and Technology Beijing, 30 Xueyuan Road, Beijing 100083, China.
Microstructure and deformation properties of both unaged and aged cladding material were studied at 400 °C for 10,000 h. The results indicated that carbide formation occurred in the cladding material, while thermal aging treatment resulted in spinodal decomposition and G-phase formation in the aged ferrite phase. Furthermore, intensive straight slip bands formed in both unaged and aged austenite phases.
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