| 1. |
- Chaudhury, Asim, et al.
(författare)
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Low silicon non-grain-oriented electrical steel: Linking magnetic properties with metallurgical factors
- 2007
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 313:1, s. 21-28
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Tidskriftsartikel (refereegranskat)abstract
- Commercial supply, from several steel manufacturers, of low-silicon non-grain-oriented electrical steel was monitored over a span of several years. A total of 51 samples were selected-selected from many hundreds on the basis of large differences in magnetic properties, but absence of significant variations in chemistry (other than differences in silicon percentage). The selected samples were analyzed for crystallographic texture and for grain size. The data were carefully analyzed to bring out the effects of metallurgical variables, namely silicon %, grain size and crystallographic texture, on the magnetic properties using explicit functional relationships as well as artificial neural network (ANN). Among the explicit relationships, power law relationship appears to offer a best fit between magnetic properties and the metallurgical factors. ANN approach to the relationship, however, brought out predicted values with least error
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| 2. |
- Goel, Sneha, 1993-, et al.
(författare)
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As-Built and Post-treated Microstructures of an Electron Beam Melting (EBM) Produced Nickel-Based Superalloy
- 2020
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Ingår i: Metallurgical and Materials Transactions. A. - : Springer Science and Business Media LLC. - 1073-5623 .- 1543-1940. ; 51:12, s. 6546-6559
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Tidskriftsartikel (refereegranskat)abstract
- The microstructures of an electron beam melted (EBM) nickel-based superalloy (Alloy 718) were comprehensively investigated in as-built and post-treated conditions, with particular focus individually on the contour (outer periphery) and hatch (core) regions of the build. The hatch region exhibited columnar grains with strong texture in the build direction, while the contour region had a mix of columnar and equiaxed grains, with no preferred crystallographic texture. Both regions exhibited nearly identical hardness and carbide content. However, the contour region showed a higher number density of fine carbides compared to the hatch. The as-built material was subjected to two distinct post-treatments: (1) hot isostatic pressing (HIP) and (2) HIP plus heat treatment (HIP + HT), with the latter carried out as a single cycle inside the HIP vessel. Both post-treatments resulted in nearly an order of magnitude decrease in defect content in hatch and contour regions. HIP + HT led to grain coarsening in the contour, but did not alter the microstructure in the hatch region. Different factors that may be responsible for grain growth, such as grain size, grain orientation, grain boundary curvature and secondary phase particles, are discussed. The differences in carbide sizes in the hatch and contour regions appeared to decrease after post-treatment. After HIP + HT, similar higher hardness was observed in both the hatch and contour regions compared to the as-built material.
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| 3. |
- Venkatesh, Lakshmi Narayanan, et al.
(författare)
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Morphology-Dependent Hardness of Cr7C3-Ni-Rich Alloy Composite vs Orientation Independent Hardness of Cr7C3 Primary Phase in a Laser Clad Microstructure
- 2017
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Ingår i: Metallurgical and Materials Transactions. A. - : Springer Science and Business Media LLC. - 1073-5623 .- 1543-1940. ; 48A:4, s. 1534-1539
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Tidskriftsartikel (refereegranskat)abstract
- Microstructural evolution with superheating was studied in chromium carbide-nickel coatings deposited by laser cladding. At lower superheating, selective growth of aOE (c) 0001 > direction from the high density of Cr7C3 grains nucleated resulted in a columnar structure with (0001) texture. Increased superheating lead to the loss of columnar structure as well as the (0001) texture. The hexagonal Cr7C3 showed an unusual isotropic nanoindentation hardness evidently correlated with its low c/a ratio. However, the rod-like morphology of the carbide dendrites resulted in significant anisotropy in the hardness of the composite.
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| 4. |
- Venkatesh, Lakshmi Narayanan, et al.
(författare)
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Room temperature and 600 °C erosion behaviour of various chromium carbide composite coatings
- 2019
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 422-423, s. 44-53
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the erosion behaviour of laser clad chromium carbide-Ni rich alloy composite coatings with a wide range of carbide contents at room temperature and 600 °C were investigated. The variation in carbide content of the coatings was due to dilution from the substrate and the high cooling rate in the laser cladding process preventing re-solidification of the molten carbides. Erosion rate was observed to be a function of carbide content alone and was significantly higher at 600 °C as compared to room temperature. Erosion wear ratio (E90/E30) was also dependent on carbide content but decreased at higher temperature and higher carbide contents. A comparison of erosion behaviour with detonation and plasma sprayed counterparts showed the superior performance of laser clad coatings at 600 °C. The poor erosion performance of the detonation and plasma sprayed coatings was due to weak splat bonding. Thick oxide layer formed on the steel substrate after pre-oxidation resulted in its poor erosion performance.
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