| 1. |
- Alvarez-Asencio, Ruben, et al.
(författare)
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Role of microstructure on corrosion initiation of an experimental tool alloy : A Quantitative Nanomechanical Property Mapping study
- 2014
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 89, s. 236-241
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Tidskriftsartikel (refereegranskat)abstract
- The adhesion properties of a FeCrVN experimental tool alloy immersed in pure water and sodium chloride solution have been studied by Quantitative Nanomechanical Property Mapping to understand the influence of microstructure on corrosion initiation of this alloy. The approach used here allows early observation and identification of pre-pitting events that may lead to passivity breakdown of the alloy. Adhesion provides a good distinction between the different regions and we ascribe this to their vanadium and nitrogen contents. Finally, the prepitting is characterized by generation of small particles in specific regions of the surface with low chromium content.
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| 2. |
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| 3. |
- Anantha, Krishnan Hariramabadran, et al.
(författare)
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Correlative Microstructure Analysis and In Situ Corrosion Study of AISI 420 Martensitic Stainless Steel for Plastic Molding Applications
- 2017
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Ingår i: Journal of the Electrochemical Society. - : Electrochemical Society. - 0013-4651 .- 1945-7111. ; 164:4, s. C85-C93
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the corrosion behavior of tempered AISI 420 martensitic stainless steel (MSS) was studied by in-situ atomic force microscopy (AFM) in 0.1M NaCl and correlated with the microstructure. Thermocalc simulation, dilatometry, and X-ray diffraction (XRD) were performed to investigate phase transformation which showed the formation of M3C, M7C3, and M23C6 type of carbides and also retained austenite. Optical microscopy, scanning electron microscopy (SEM), and AFM characterization revealed undissolved carbides and tempering carbides in the martensitic matrix. Volta potential mapping measured by scanning Kelvin probe force microscopy (SKPFM) indicated higher electrochemical (practical) nobility of the carbides with respect to the martensitic matrix whereas regions adjacent to carbides showed lower nobilities due to chromium depletion. Open circuit potential and cyclic potentiodynamic polarization measurements showed metastable corrosion activities associated with a weak passive behavior and a risk for localized corrosion along certain carbide boundaries. In-situ AFM measurements revealed selective dissolution of certain carbide interphases and martensitic inter-lath regions indicating higher propensity to localized corrosion.
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| 4. |
- Anantha, Krishnan Hariramabadran, et al.
(författare)
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Experimental and modelling study of the effect of tempering on the susceptibility to environment-assisted cracking of AISI 420 martensitic stainless steel
- 2019
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Ingår i: Corrosion Science. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0010-938X .- 1879-0496. ; 148, s. 83-93
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Tidskriftsartikel (refereegranskat)abstract
- The resistance to environment-assisted cracking (EAC) of AISI 420 martensitic stainless steel (MSS) was investigated in 0.3 M NaCl solution (room temperature) at constant loads for 30 days. The steel tempered at 250 degrees C was superior to the 500 degrees C-temper, which showed corrosion pits favouring cracking. The fracture surface showed faceted grains, cleavage, striations, and inter- and transgranular cracks, suggesting a mixed stress corrosion cracking (SCC) and hydrogen embrittlement (HE) mechanism as the cause for EAC. Finite element modelling (FEM) indicated strain/stress localization at the mouth of deep pits and at the wall of shallow pits, displaying the favoured locations for pit-to-crack transition.
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| 5. |
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| 7. |
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| 8. |
- Sababi, Majid, et al.
(författare)
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Microstructure influence on corrosion behavior of a Fe-Cr-V-N tool alloy studied by SEM/EDS, scanning Kelvin force microscopy and electrochemical measurement
- 2013
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 66, s. 153-159
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Tidskriftsartikel (refereegranskat)abstract
- Microstructure influence on corrosion behavior of an N-based tool alloy (Fe-Cr-V-N) has been studied. Electron microscopy analysis showed two types of hard phases in the alloy. One-pass mode scanning Kelvin force microscopy (KFM) was used to investigate relative nobility of the hard phases. Volta potential mapping indicates higher nobility for the hard phases than the alloy matrix, and, the V- and N-rich particles exhibit the highest Volta potential. Post-polarization analysis by SEM revealed localized dissolution initiated in matrix regions adjacent to hard phase particles, and the boundary region surrounding the Cr- and Mo-rich particles is more prone to localized corrosion.
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| 9. |
- Shinde, Deodatta, et al.
(författare)
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Improving Compositional Accuracy in APT Analysis of Carbides Using a Decreased Detection Efficiency
- 2019
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Ingår i: Microscopy and Microanalysis. - 1435-8115 .- 1431-9276. ; 25:2, s. 454-461
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Tidskriftsartikel (refereegranskat)abstract
- The composition of carbides in steel, measured by atom probe tomography, can be influenced by limitations in the ion detector system. When carbides are analyzed, many ions tend to field evaporate from the same region of the specimen during the same laser or voltage pulse. This results in a so-called multiple event, meaning that several ions impact the detector in close proximity both in time and space. Due to a finite detector dead-time not all ions can be detected, a phenomenon known as detector pile-up. The evaporation behavior of carbon is often different than the evaporation behavior of metals when analyzing alloy carbides, leading to preferential loss of carbon ions, and a measured carbon concentration below the expected value. This effect becomes stronger as the overall detection efficiency gets higher. Here, the detection efficiency was deliberately reduced by inserting a grid into the flight-path, which resulted in a higher and more correct carbon concentration, accompanied by an increase in the statistical uncertainty.
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| 10. |
- Yue, Xiaoqi, et al.
(författare)
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Unveiling nano-scale chemical inhomogeneity in surface oxide films formed on V- and N-containing martensite stainless steel by synchrotron X-ray photoelectron emission spectroscopy/microscopy and microscopic X-ray absorption spectroscopy
- 2025
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Ingår i: Journal of Materials Science & Technology. - : Chinese Society of Metals. - 1005-0302. ; 205, s. 191-203
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Tidskriftsartikel (refereegranskat)abstract
- Nano-scale chemical inhomogeneity in surface oxide films formed on a V- and N-containing martensite stainless steel and tempering heating induced changes are investigated by a combination of synchrotron- based hard X-ray Photoelectron emission spectroscopy (HAXPES) and microscopy (HAXPEEM) as well as microscopic X-ray absorption spectroscopy (μ-XAS) techniques. The results reveal the inhomogeneity in the oxide films on the micron-sized Cr2N- and VN-type particles, while the inhomogeneity on the martensite matrix phase exists due to localised formation of nano-sized tempering nitride particles at 600 °C. The oxide film formed on Cr2N-type particles is rich in Cr2O3 compared with that on the martensite matrix and VN-type particles. With the increase of tempering temperature, Cr2O3 formation is faster for the oxidation of Cr in the martensite matrix than the oxidation of Cr nitride-rich particles.
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