Characterization of the surface of Fe–19Mn–18Cr–C–N during heat treatment in a high vacuum — An XPS study

Zumsande, Kathrin; Weddeling, Anna; Hryha, Eduard; Huth, S.; Nyborg, Lars; Weber, Sebastian; Krasokha, N.; Theisen, W.

doi:10.1016/j.matchar.2012.06.002

Cited by 23 publications

(20 citation statements)

References 13 publications

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“…The presented EDX results indicate that the particulates present in the HIP, SSS, and the SLPS specimens are of oxidic character and feature about similar chemical compositions independently from consolidation route. EDX measurements also indicate a silicon fraction, which suggest that most obtained oxides are thermodynamically very stable Mn-Cr-Si oxides which are in agreement with previous investigations [23] and literature. [32] The Si fraction could not be measured accurately by XPS because the oxide content on the fracture surface of the specimens is rather low and thus the silicon peak was too small to be fitted accurately.…”

Section: Chemical Analysissupporting

confidence: 91%

“…[22,23] Within this series of experiments, however, the Mn-content indicates no evaporation of this element for all investigated specimens due to the lower vacuum levels applied.…”

Section: Chemical Analysismentioning

confidence: 84%

“…[25,26] Moreover, Mn evaporation is calculated to strongly increase above 973 K (700°C), [24] which is also supported by experimental investigations. [23] Additionally, a dwelling step at 1423 K (1150°C) was performed because RGA, depicted in Figure 2(a), [27] revealed carbothermal reduction of surface oxides until this temperature in vacuum.…”

Section: B Design Of Sintering Routementioning

confidence: 99%

“…Nitrogen may degas and the high vapor pressure of Mn leads to its evaporation sublimation at temperatures above 973 K (700°C) in high vacuum. [22][23][24] Another problem is the enclosure of the surface oxides in the developing inter-particle necks resulting in a decreased performance of sintered steel as they act as crack initiation sites. Whereas less stable oxides, like iron oxides, are reduced during the sintering cycle; the more thermodynamically stable Mn-rich oxides may become enclosed during consolidation.…”

Section: Introductionmentioning

confidence: 99%

“…This is especially critical as they incline to transform into even more stable Si-containing mixed oxides abovẽ 1073 K (~800°C). [23] For that reason, the parameters of the sintering process, such as the atmosphere and the temperature profile, have to be adapted to the material regarding both, the densification and the oxide reduction. This study investigates the influence of PM-processing route on the mechanical properties of sintered N-containing Ni-free austenitic stainless steel.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the PM-Processing Route and Nitrogen Content on the Properties of Ni-Free Austenitic Stainless Steel

Lefor

Walter

Weddeling

et al. 2014

Metall Mater Trans A

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Ni-free austenitic steels alloyed with Cr and Mn are an alternative to conventional Ni-containing steels. Nitrogen alloying of these steel grades is beneficial for several reasons such as increased strength and corrosion resistance. Low solubility in liquid and d-ferrite restricts the maximal N-content that can be achieved via conventional metallurgy. Higher contents can be alloyed by powder-metallurgical (PM) production via gas-solid interaction. The performance of sintered parts is determined by appropriate sintering parameters. Three major PM-processing routes, hot isostatic pressing, supersolidus liquid phase sintering (SLPS), and solid-state sintering, were performed to study the influence of PM-processing route and N-content on densification, fracture, and mechanical properties. Sintering routes are designed with the assistance of thermodynamic calculations, differential thermal analysis, and residual gas analysis. Fracture surfaces were studied by X-ray photoelectron spectroscopy, secondary electron microscopy, and energy dispersive X-ray spectroscopy. Tensile tests and X-ray diffraction were performed to study mechanical properties and austenite stability. This study demonstrates that SLPS process reaches high densification of the high-Mn-containing powder material while the desired N-contents were successfully alloyed via gas-solid interaction. Produced specimens show tensile strengths >1000 MPa combined with strain to fracture of 60 pct and thus overcome the other tested production routes as well as conventional stainless austenitic or martensitic grades.

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Section: Chemical Analysissupporting

confidence: 91%

“…[22,23] Within this series of experiments, however, the Mn-content indicates no evaporation of this element for all investigated specimens due to the lower vacuum levels applied.…”

Section: Chemical Analysismentioning

confidence: 84%

Section: B Design Of Sintering Routementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of the PM-Processing Route and Nitrogen Content on the Properties of Ni-Free Austenitic Stainless Steel

Lefor

Walter

Weddeling

et al. 2014

Metall Mater Trans A

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Processing of High Interstitial Austenitic Steel with Powder Bed Fusion‐Laser Beam/Metal: Evolution of Chemical Inhomogeneity and Microstructural Features during Postprocessing

Kimm,

Hanke,

Weber

et al. 2024

Adv Eng Mater

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Powder Bed Fusion‐Laser Beam/Metal (PBF LB/M) additive manufacturing provides a high potential to overcome the poor machinability of nickel‐free high interstitial alloy austenitic (HIA) steels. Therefore, this study focuses on the PBF LB/M processibility of HIA X40MnCrMoN21‐18‐2 and the effect of post‐processing on microstructure and chemical homogeneity. Samples were fabricated on a laboratory and industrial PBF‐LB/M machine and subsequently post‐processed by conventional solution annealing or hot isostatic pressing (HIP). The influence of the processing steps on the microstructure and on the chemical composition was evaluated by scanning electron microscopy, X‐ray diffraction, transmission electron microscopy, atom probe tomography and electron backscatter diffraction. The commercially available HIA powder exerts good processability, both by optimized and pre‐defined PBF LB/M parameters. Loss of Mn and N was detected after PBF‐LB/M processing. Chemical homogenization but no further change in composition occurred during post‐processing. The as‐built microstructure showed segregation of elements (N, Mo, Cr, Mn) in intercellular spaces. A thermodynamic calculation confirmed that N approaches a para‐equilibrium state in the PBF‐LB/M as‐built condition, while C does not. Porosity could be reduced by thermomechanical post‐treatment with HIP. At the same time, HIP partially recrystallized the microstructure, while (Mn+Cr)2SiO4 type oxides delayed recovery and recrystallization of the microstructure.This article is protected by copyright. All rights reserved.

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Nitrogen uptake of nickel free austenitic stainless steel powder during heat treatment-an XPS study

Weddeling

Lefor

Hryha

et al. 2014

Surf. Interface Anal.

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In austenitic stainless steel nitrogen stabilizes the austenitic phase, improves the mechanical properties and increases the corrosion resistance. Nitrogen alloying enables to produce austenitic steels without the element nickel which is high priced and classified as allergy inducing. A novel production route is nitrogen alloying of CrMn‐prealloyed steel powder via the gas phase. This is beneficial as the nitrogen content can be adjusted above the amount that is reached during conventional casting. A problem which has to be overcome is the oxide layer present on the powder surface which impedes both the sintering process and the uptake of nitrogen. This study focuses on whether heat treatment under pure nitrogen is an appropriate procedure to enable sintering and nitrogen uptake by reduction of surface oxides. X‐ray photoelectron spectroscopy (XPS) in combination with scanning electron microscopy (SEM) and energy dispersive X‐ray spectrometry (EDS) are used to investigate the surface of powdered FeMn19Cr17C0.4N heat treated under nitrogen atmosphere. The analyses showed reduction of iron oxides already at 500 °C leading to oxide‐free metallic surface zones. Mn and Cr oxides are reduced at higher temperatures. Distinct nitrogen uptake was registered, and successful subsequent sintering was reached. Copyright © 2014 John Wiley & Sons, Ltd.

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Characterization of the surface of Fe–19Mn–18Cr–C–N during heat treatment in a high vacuum — An XPS study

Cited by 23 publications

References 13 publications

Influence of the PM-Processing Route and Nitrogen Content on the Properties of Ni-Free Austenitic Stainless Steel

Influence of the PM-Processing Route and Nitrogen Content on the Properties of Ni-Free Austenitic Stainless Steel

Processing of High Interstitial Austenitic Steel with Powder Bed Fusion‐Laser Beam/Metal: Evolution of Chemical Inhomogeneity and Microstructural Features during Postprocessing

Nitrogen uptake of nickel free austenitic stainless steel powder during heat treatment-an XPS study

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