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Hou, Z., Linder, D., Hedström, P., Forsberg, A., Holmström, E. & Ström, V. (2019). Effect of carbon content on the Curie temperature of WC-NiFe cemented carbides. International Journal of Refractory Metals and Hard Materials, 78, 27-31
Open this publication in new window or tab >>Effect of carbon content on the Curie temperature of WC-NiFe cemented carbides
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2019 (English)In: International Journal of Refractory Metals and Hard Materials, ISSN 0263-4368, Vol. 78, p. 27-31Article in journal (Refereed) Published
Abstract [en]

We have investigated the effect of the carbon content on the Curie temperature of a cemented carbide composite material with a Ni-Fe alloy as the binder phase and WC as the hard phase. In the carbon concentration range from 5.72 to 5.83 wt% carbon, which covers the interval where WC coexists with fcc Ni-Fe without other phases (the ‘carbon window’), the Curie temperature rises from 200 to 527 °C. This result indicates the possibility to use the Curie temperature to determine the carbon balance in the system. With thermodynamic calculations and kinetic simulations we can quantitatively establish the correlation between the carbon and tungsten content of the binder phase and the Curie temperature. This strong compositional effect on the Curie temperature is quantitatively very different from the conventional Co-based cemented carbides, with Curie temperatures of about 950–1050 °C.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Alternative binder, Carbon window, Cemented carbide, Curie temperature, Hard metals, Binary alloys, Binders, Carbide tools, Carbides, Cobalt compounds, Iron alloys, Nickel alloys, Carbon concentrations, Cemented carbide composites, Cemented carbides, Compositional effects, Effect of carbons, Kinetic simulation, Thermodynamic calculations, Temperature
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-236334 (URN)10.1016/j.ijrmhm.2018.08.010 (DOI)000451489300003 ()2-s2.0-85052282006 (Scopus ID)
Note

QC 20181109

Available from: 2018-11-09 Created: 2018-11-09 Last updated: 2018-12-11Bibliographically approved
Bonvalet, M., Odqvist, J., Ågren, J. & Forsberg, A. (2019). Modelling of prismatic grain growth in cemented carbides. INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS, 78, 310-319
Open this publication in new window or tab >>Modelling of prismatic grain growth in cemented carbides
2019 (English)In: INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS, ISSN 0263-4368, Vol. 78, p. 310-319Article in journal (Refereed) Published
Abstract [en]

A mean-field model dealing with prismatic grain growth during liquid phase sintering of cemented carbides with a Co-rich binder is presented. The evolution of the size of an assembly of non-spherical grains is obtained using a Kampmann-Wagner approach and by introducing a constant shape factor between the characteristic lengths of prisms. This factor is a function of interfacial energies of the two kind of facets, basal and prismatic, considered. The growth model is based on three different mechanisms, that can be rate limiting, taking place in series: 2D nucleation of a new atomic layer, mass transfer across the interface and long-range diffusion. The driving force for coarsening is distributed between the different facets. These equations are solved numerically, and the simulation results reveal that the specific abnormal grain growth phenomena experimentally observed in cemented carbides may be reproduced with this new more realistic description of the grain shape contrary to the spherical approach developed in the past. It is also shown that the initial powder size distribution, and more specifically its shape has a strong influence on the distribution of the driving force between the different rate limiting mechanisms and thus on the occurrence of abnormal grain growth. In that case, the self-similarity of the normalized grain size distribution over time is not achieved.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2019
Keywords
Grain coarsening, Abnormal grain growth, Cemented carbides, Modelling, Liquid phase sintering
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-239962 (URN)10.1016/j.ijrmhm.2018.10.007 (DOI)000451489300038 ()2-s2.0-85055672266 (Scopus ID)
Funder
VINNOVA
Note

QC 20181211

Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-11Bibliographically approved
Walbrühl, M., Linder, D., Ågren, J. & Borgenstam, A. (2018). A new hardness model for materials design in cemented carbides. International Journal of Refractory Metals and Hard Materials, 75, 94-100
Open this publication in new window or tab >>A new hardness model for materials design in cemented carbides
2018 (English)In: International Journal of Refractory Metals and Hard Materials, ISSN 0263-4368, Vol. 75, p. 94-100Article in journal (Refereed) Published
Abstract [en]

The Materials Design approach offers new possibilities towards property-oriented materials development. The performance of cemented carbides is significantly influenced by properties like the hardness and fracture toughness. Fundamentally based phenomenological models, which allow for prediction of the properties of interest, make it possible to tailor the properties of the material based on the required performance. None of the previously available models are suitable to actively design the cemented carbide hardness because they are valid only for Co binders and do not allow alternative binder phases. The hardness is greatly influenced by the chemistry, binder volume fraction and carbide grain size. Only the chemistry, specifically the binder composition, leaves the possibility to optimize the binder hardness and to exceed classical WC-Co cemented carbides. Specifically focusing on the design of the binder phase, a new binder hardness description is implemented in a modified Engqvist hardness model and allows description of a wider range of conventional and alternative systems. The model was validated for various published cemented carbide systems and is able to predict their hardness within a 10% error. The assessed systems contain classical Co binders as well as alternative, austenitic binders based on Fe, Ni and Co.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Alternative binder, Cemented carbides, ICME, Materials design, Solid solution strengthening, Thermo-Calc
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-227506 (URN)10.1016/j.ijrmhm.2018.04.004 (DOI)000437362100013 ()2-s2.0-85045428618 (Scopus ID)
Note

QC 20180518

Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2018-07-23Bibliographically approved
Tian, Y., Forsberg, A. & Hedström, P. (2018). Comparing the deformation-induced martensitic transformation with the athermal martensitic transformation in Fe-Cr-Ni alloys. Journal of Alloys and Compounds, 766, 131-139
Open this publication in new window or tab >>Comparing the deformation-induced martensitic transformation with the athermal martensitic transformation in Fe-Cr-Ni alloys
2018 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 766, p. 131-139Article in journal (Refereed) Published
Abstract [en]

The microstructure of martensite formed athermally or via deformation in Fe-Cr-Ni alloys with different austenite (gamma) stability has been investigated using microscopy. Two different types of microstructures, viz. blocky and banded structure, are observed after athermal and deformation-induced martensitic transformation (AMT and DIMT, respectively). The blocky structure form during AMT or DIMT if the stability of gamma is low. In both cases, there is a significant chemical driving force for the transformation from gamma to alpha'-martensite (alpha'), and if it is not hindered by e.g. planar defects it can grow uninhibited into a blocky morphology without the necessity to nucleate new crystallographic variants to accommodate the transformation strains. On the other hand, the banded structure is due to the formation of epsilon-martensite (epsilon) during AMT, or the wider concept shear bands in the case of DIMT. The shear bands, and in particular epsilon, lower the nucleation barrier for alpha' that forms within individual shear bands if the stability of gamma is low. Neighbouring alpha' units predominantly have a twin-related orientation relationship to accommodate the transformation strains. With increasing y stability during DIMT, variant selection becomes pronounced with preferred formation of variants favorable oriented with respect to the applied stress/strain field. The formation of alpha' at individual shear bands is also rare, since nos is present and instead alpha' forms at the intersection of shear bands for more stable gamma. In conclusion, AMT and DIMT for low gamma stability lead to similar microstructures, whereas the DIMT microstructure for high y stability is distinct. 

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2018
Keywords
Metastable austenite, Deformation-induced martensitic transformation, Deformation microstructure, Variant pairing tendency, Variant selection
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-235554 (URN)10.1016/j.jallcom.2018.06.326 (DOI)000444617200014 ()2-s2.0-85049301116 (Scopus ID)
Note

QC 20181002

Available from: 2018-10-02 Created: 2018-10-02 Last updated: 2018-10-02Bibliographically approved
Tian, Y., Lin, S., Ko, J. Y., Lienert, U., Forsberg, A. & Hedström, P. (2018). Micromechanics and microstructure evolution during in situ uniaxial tensile loading of TRIP-assisted duplex stainless steels. Materials Science & Engineering: A, 734, 281-290
Open this publication in new window or tab >>Micromechanics and microstructure evolution during in situ uniaxial tensile loading of TRIP-assisted duplex stainless steels
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2018 (English)In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 734, p. 281-290Article in journal (Refereed) Published
Abstract [en]

Transformation-induced plasticity (TRIP) assisted duplex stainless steels, with three different stabilities of the austenite phase, were investigated by synchrotron x-ray diffraction characterization during in situ uniaxial tensile loading. The micromechanics and the deformation-induced martensitic transformation (DIMT) in the bulk of the steels were investigated in situ. Furthermore, scanning electron microscopy supplemented the in situ analysis by providing information about the microstructure of annealed and deformed specimens. The dependence of deformation structure on austenite stability is similar to that of single-phase austenitic steels with shear bands and bcc-martensite (α′) generally observed, and blocky α′ is only frequent when the austenite stability is low. These microstructural features, i.e. defect structure and deformation-induced martensite, are correlated with the micro- and macro-mechanics of the steels with elastoplastic load transfer from the weaker phases to the stronger α′, in particular this occurs close to the point of maximum rate of α′ formation. A clear strain-hardening effect from α′ is seen in the most unstable austenite leading to a pronounced TRIP effect. 

Place, publisher, year, edition, pages
Elsevier Ltd, 2018
Keywords
Duplex stainless steel, in situ tensile loading, Load partitioning, Micromechanics, Synchrotron x-ray diffraction, TRIP-assisted steel, Austenite, Austenitic transformations, Crystal structure, Deformation, High strength steel, Martensite, Martensitic transformations, Microstructural evolution, Plasticity, Scanning electron microscopy, Strain hardening, Synchrotron radiation, Tensile stress, X ray diffraction, Deformation-induced martensite, In-situ tensile, Micro-structure evolutions, Microstructural features, Synchrotron x ray diffraction, Transformation induced plasticity, TRIP-assisted steels, Loading
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-236692 (URN)10.1016/j.msea.2018.07.040 (DOI)000445993900032 ()2-s2.0-85050988500 (Scopus ID)
Funder
VINNOVA
Note

Export Date: 22 October 2018; Article; Correspondence Address: Tian, Y.; Department of Materials Science and Engineering, KTH Royal Institute of TechnologySweden; email: yti@kth.se; Funding details: CSC, China Scholarship Council; Funding details: 2i; Funding details: Axelrod Family Foundation; Funding details: VINNOVA; Funding details: Jernkontoret; Funding details: DMR-1332208, BSF, United States-Israel Binational Science Foundation; Funding text: This work was performed within the VINN Excellence Centre Hero-m 2i, financed by VINNOVA , the Swedish Government Agency of Innovation Systems , Swedish Industry and KTH . This work is based upon research conducted at the Cornell High Energy Synchrotron Source (CHESS) which is supported by the United States National Science Foundation under award DMR-1332208 . The authors are grateful to Darren Dale, Margaret Koker, Prasath Babu R, Yan Ma, Fei Huyan, Sven Gutschmidt and Basil Blank for technical assistance, and Jan Y. Jonsson from Outokumpu for providing the materials. Y. Tian would like to express his gratitude to the support from CSC (China Scholarship Council) and Axel Hultgrens foundation. P. Hedström acknowledges the support from Jernkontoret (Swedish Steel Producers’ association). QC 20181112

Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2018-11-12Bibliographically approved
Yvell, K., Grehk, T. M., Hedström, P., Borgenstam, A. & Engberg, G. (2018). Microstructure development in a high-nickel austenitic stainless steel using EBSD during in situ tensile deformation. Materials Characterization, 135, 228-237
Open this publication in new window or tab >>Microstructure development in a high-nickel austenitic stainless steel using EBSD during in situ tensile deformation
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2018 (English)In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 135, p. 228-237Article in journal (Refereed) Published
Abstract [en]

Plastic deformation of surface grains has been observed by electron backscatter diffraction technique during in situ tensile testing of a high-nickel austenitic stainless steel. The evolution of low- and high-angle boundaries as well as the orientation changes within individual grains has been studied. The number of low-angle boundaries and their respective misorientation increases with increasing strain and some of them also evolve into high-angle boundaries leading to grain fragmentation. The annealing twin boundaries successively lose their integrity with increasing strain. The changes in individual grains are characterized by an increasing spread of orientations and by grains moving towards more stable orientations with < 111 > or < 001 > parallel to the tensile direction. No deformation twins were observed and deformation was assumed to be caused by dislocation slip only.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Austenitic stainless steels, Electron backscatter diffraction (EBSD), In situ tension test, Grain boundaries, grain rotation
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-222442 (URN)10.1016/j.matchar.2017.11.046 (DOI)000423248200027 ()2-s2.0-85035068432 (Scopus ID)
Note

QC 20180219

Available from: 2018-02-19 Created: 2018-02-19 Last updated: 2018-05-14Bibliographically approved
Linder, D., Ågren, J. & Forsberg, A. (2017). Bridging the Gap Between Bulk Properties and Confined Behavior Using Finite Element Analysis. In: Mason, P Fisher, CR Glamm, R Manuel, MV Schmitz, GJ Singh, AK Strachan, A (Ed.), PROCEEDINGS OF THE 4TH WORLD CONGRESS ON INTEGRATED COMPUTATIONAL MATERIALS ENGINEERING (ICME 2017): . Paper presented at 4th World Congress on Integrated Computational Materials Engineering (ICME), MAY 21-25, 2017, Ypsilanti, MI (pp. 103-111). SPRINGER INTERNATIONAL PUBLISHING AG
Open this publication in new window or tab >>Bridging the Gap Between Bulk Properties and Confined Behavior Using Finite Element Analysis
2017 (English)In: PROCEEDINGS OF THE 4TH WORLD CONGRESS ON INTEGRATED COMPUTATIONAL MATERIALS ENGINEERING (ICME 2017) / [ed] Mason, P Fisher, CR Glamm, R Manuel, MV Schmitz, GJ Singh, AK Strachan, A, SPRINGER INTERNATIONAL PUBLISHING AG , 2017, p. 103-111Conference paper, Published paper (Refereed)
Abstract [en]

Theoretically and empirically based models of materials properties are crucial tools in development of new materials; however, these models are often restricted to certain systems due to assumptions or fitting parameters. When expanding a model into alternative systems it is therefore necessary to have sufficient experimental data. When working with composite or highly confined materials, such as layered structures or coatings, this can be problematic as most available data is on bulk materials. The present work displays the potential of using Finite Element Method (FEM) simulations as a tool to understand experimental observations and expand existing models to new systems using only bulk properties of the constituent phases. The present work focuses on the effect of geometrical constraints on the indentation behavior of elasto-plastic materials as an example on how FEM may be used to better understand experimental observations in composite or layered materials. The results may also be integrated into phenomenological models, expanding their application range.

Place, publisher, year, edition, pages
SPRINGER INTERNATIONAL PUBLISHING AG, 2017
Series
Minerals Metals & Materials Series, ISSN 2367-1181
Keywords
Indentation behavior, Confined hardness, Finite element analysis
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-223882 (URN)10.1007/978-3-319-57864-4_10 (DOI)000424820100010 ()2-s2.0-85042460080 (Scopus ID)978-3-319-57864-4 (ISBN)978-3-319-57863-7 (ISBN)
Conference
4th World Congress on Integrated Computational Materials Engineering (ICME), MAY 21-25, 2017, Ypsilanti, MI
Funder
VINNOVA
Note

QC 20180305

Available from: 2018-03-05 Created: 2018-03-05 Last updated: 2018-03-05Bibliographically approved
Tian, Y., Lienert, U., Borgenstam, A., Fischer, T. & Hedström, P. (2017). Martensite formation during incremental cooling of Fe-Cr-Ni alloys: An in-situ bulk X-ray study of the grain-averaged and single-grain behavior. Scripta Materialia, 136, 124-127
Open this publication in new window or tab >>Martensite formation during incremental cooling of Fe-Cr-Ni alloys: An in-situ bulk X-ray study of the grain-averaged and single-grain behavior
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2017 (English)In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 136, p. 124-127Article in journal (Refereed) Published
Abstract [en]

The formation of martensite (epsilon and alpha') in metastable austenitic Fe-18Cr-(10-11.5)Ni alloys was investigated in situ during cooling. High-energy X-rays were used to study the bulk of the alloys. Both grain-averaged and single grain data was acquired. s played an important role in the formation of a' with an indistinguishable difference in the martensite start temperature. The single-grain data indicated that stacking faults appear as precursors to a An analogy can be made with deformation-induced martensitic transformation, where the generation of nucleation sites would significantly lower the driving force required to overcome the energy barrier in low stacking fault energy Fe-Cr-Ni alloys.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Martensitic phase transformation, Synchrotron radiation, Austenitic stainless steel, In-situ investigation, Three-dimensional X-ray diffraction (3DXRD)
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-210454 (URN)10.1016/j.scriptamat.2017.04.020 (DOI)000402943600028 ()2-s2.0-85018433587 (Scopus ID)
Funder
VINNOVA
Note

QC 20170706

Available from: 2017-07-06 Created: 2017-07-06 Last updated: 2018-05-16Bibliographically approved
Yin, J., Hillert, M. & Borgenstam, A. (2017). Morphology of Proeutectoid Ferrite. Metallurgical and Materials Transactions. A, 48A(3), 1425-1443
Open this publication in new window or tab >>Morphology of Proeutectoid Ferrite
2017 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 48A, no 3, p. 1425-1443Article in journal (Refereed) Published
Abstract [en]

The morphology of grain boundary nucleated ferrite particles in iron alloys with 0.3 mass pct carbon has been classified according to the presence of facets. Several kinds of particles extend into both grains of austenite and have facets to both. It is proposed that they all belong to a continuous series of shapes. Ferrite plates can nucleate directly on the grain boundary but can also develop from edges on many kinds of particles. Feathery structures of parallel plates on both sides of a grain boundary can thus form. In sections, parallel to their main growth direction, plates have been seen to extend the whole way from the nucleation site at the grain boundary and to the growth front. This happens in the whole temperature range studied from 973 K to 673 K (700 A degrees C to 400 A degrees C). The plates thus grow continuously and not by subunits stopping at limited length and continuing the growth by new ones nucleating. Sometimes, the plates have ridges and in oblique sections they could be mistaken for the start of new plates. No morphological signs were observed indicating a transition between Widmanstatten ferrite and bainitic ferrite. It is proposed that there is only one kind of acicular ferrite. (C) The Author(s) 2016. This article is published with open access at Springerlink.com

Place, publisher, year, edition, pages
Springer, 2017
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-204065 (URN)10.1007/s11661-016-3903-y (DOI)000394214300042 ()2-s2.0-85008477493 (Scopus ID)
Note

QC 20170330

Available from: 2017-03-30 Created: 2017-03-30 Last updated: 2017-06-29Bibliographically approved
Yin, J., Hillert, M. & Borgenstam, A. (2017). Second Stage of Upper Bainite in a 0.3 Mass Pct C Steel. Metallurgical and Materials Transactions. A, 48A(3), 1444-1458
Open this publication in new window or tab >>Second Stage of Upper Bainite in a 0.3 Mass Pct C Steel
2017 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 48A, no 3, p. 1444-1458Article in journal (Refereed) Published
Abstract [en]

Upper bainite forms in at least two stages, the formation of parallel plates of ferrite and the transformation of the interspaces to a mixture of cementite and ferrite. The first stage was examined in a preceding metallographic study of the formation of ferrite in hypoeutectoid steels and the second stage, which is initiated by the occurrence of cementite in the interspaces, is the subject of the present study. The alloy from the preceding study will also be used here. The band of austenite in the interspaces between parallel plates is generally transformed by a degenerate eutectoid transformation when this band is thin. When it is thicker, it will transform by a more cooperative growth mechanism and result in a eutectoid colony, often with cementite platelets. A series of sketches are presented which illustrate in detail how the second stage of upper bainite progresses according to the present observations. The cooperative manner did not increase as the temperature was lowered because the tendency to form plates of ferrite was still increasing at lower temperatures, making the interspaces too narrow for the cooperative reaction to dominate over the formation of fine plates of ferrite. (C) The Author(s) 2016. This article is published with open access at Springerlink.com

Place, publisher, year, edition, pages
Springer, 2017
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-204066 (URN)10.1007/s11661-016-3902-z (DOI)000394214300043 ()2-s2.0-85008511996 (Scopus ID)
Note

QC 20170330

Available from: 2017-03-30 Created: 2017-03-30 Last updated: 2017-06-29Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-7656-9733

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