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Publications (10 of 15) Show all publications
Hernando, J. C., Elfsberg, J., Ghassemali, E., Dahle, A. & Diószegi, A. (2020). The role of primary austenite morphology in hypoeutectic compacted graphite iron alloys. International Journal of metalcasting
Open this publication in new window or tab >>The role of primary austenite morphology in hypoeutectic compacted graphite iron alloys
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2020 (English)In: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193Article in journal (Refereed) Epub ahead of print
Abstract [en]

This work investigates the role of primary austenite morphology on the eutectic and eutectoid microstructures and the ultimate tensile strength (UTS) in a hypoeutectic compacted graphite iron (CGI) alloy. The morphology of primary austenite is modified by isothermal coarsening experiments in which holding times up to 60 min are applied to the solid–liquid region after coherency. The cooling conditions for the subsequent eutectic and eutectoid reactions are similar. Miniaturized tensile tests are performed to evaluate the UTS. The morphological characteristics related to the surface area of primary austenite, the modulus of primary austenite, Mγ, and the hydraulic diameter of the interdendritic region, DHydID, increase with the cube root of coarsening time. The eutectic and eutectoid microstructures are not significantly affected by the morphology of primary austenite, thus indicating that the morphology of the interdendritic regions does not control the nucleation frequency and growth of eutectic cells or graphite. UTS decreases linearly with the increasing coarseness of primary austenite for similar eutectic and eutectoid microstructures, demonstrating the strong influence of primary austenite morphology on the UTS in hypoeutectic CGI alloys.

Place, publisher, year, edition, pages
Springer, 2020
Keywords
cast iron, compacted graphite iron, CGI, solidification, dendrites, primary austenite, UTS
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-47569 (URN)10.1007/s40962-020-00410-9 (DOI)2-s2.0-85078435803 (Scopus ID)
Funder
Vinnova, 2013-03303Knowledge Foundation, 2018-0033
Note

This paper is an invited submission to IJMC selected from presentations at the 2nd Carl Loper 2019 Cast Iron Symposium held September 30 to October 1, 2019, in Bilbao, Spain.

Available from: 2020-01-28 Created: 2020-01-28 Last updated: 2020-02-05
Hernando, J. C., Elfsberg, J., Dahle, A. & Diószegi, A. (2019). Evolution of primary austenite and its influence on eutectic microstructures during coarsening of Fe-C-Si alloys. Materialia, 7, Article ID 100391.
Open this publication in new window or tab >>Evolution of primary austenite and its influence on eutectic microstructures during coarsening of Fe-C-Si alloys
2019 (English)In: Materialia, ISSN 2589-1529, Vol. 7, article id 100391Article in journal (Refereed) Published
Abstract [en]

The evolution of primary austenite morphology during isothermal coarsening has been studied in the three main Fe–C–Si alloys used in industry, LGI, CGI, and SGI. The dendritic microstructure increases length scale during coarsening accompanied by fragmentation and coalescence of austenite crystals. The morphological parameters, SDAS, Mγ, DhydID, and Dγ show a linear relation with the cube root of coarsening time, t1/3, with similar rates for the three different Fe–C–Si alloys. The eutectic microstructures after coarsening of primary austenite in CGI and SGI alloys are not significantly affected by the surface area of primary austenite and the size of the interdendritic regions. Fraction, nodularity, shape distribution of graphite particles and the number of nodules and eutectic cells are similar when studied as a function of coarsening time. These results suggest that the nucleation frequency in CGI and SGI, and the growth of eutectic microstructures in CGI, are not significantly influenced by the morphology of primary austenite.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Solidification; Coarsening; Dendrites; Austenite; Eutectic; EBSD; CGI; SGI
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-43552 (URN)10.1016/j.mtla.2019.100391 (DOI)2-s2.0-85068795536 (Scopus ID)PP JTH 2019 embargo 24 (Local ID)PP JTH 2019 embargo 24 (Archive number)PP JTH 2019 embargo 24 (OAI)
Funder
VinnovaKnowledge Foundation
Note

Included in thesis in manuscript form with the title "Evolution of primary austenite and its influence on eutectic microstructures during coarsening of Fe-C-Si alloys".

Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-09-02Bibliographically approved
Santos, J., Jarfors, A. E. .. & Dahle, A. (2019). Formation of Iron-Rich Intermetallic Phases in Al-7Si-Mg: Influence of Cooling Rate and Strontium Modification. Metallurgical and Materials Transactions. A, 50(9), 4148-4165
Open this publication in new window or tab >>Formation of Iron-Rich Intermetallic Phases in Al-7Si-Mg: Influence of Cooling Rate and Strontium Modification
2019 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 50, no 9, p. 4148-4165Article in journal (Refereed) Published
Abstract [en]

The influence of cooling rate on the formation of iron-rich intermetallic phases during solidification of unmodified and strontium-modified Al-7Si-0.3Mg alloys has been investigated. The effect of strontium on the intermetallic phases was evaluated in unquenched and quenched samples. Samples were quenched before the start of the Al-Si eutectic reaction, along the Al-Si eutectic reaction and just after the end of solidification. The results show that the addition of strontium increased the size of both β-Al5FeSi and π-Al8FeMg3Si6 at low cooling rates. For unmodified and strontium-modified alloys, an increase of cooling rate resulted in a decrease in size of the intermetallic phases, particularly in the strontium modified alloy. In the strontium modified alloy quenched before the start of the Al-Si eutectic reaction, π-Al8FeMg3Si6 appeared as thin platelets at the eutectic cell boundaries. Chinese script-like π-Al8FeMg3Si6 and platelet-like β-Al5FeSi intermetallic phases were observed uniformly distributed in the eutectic regions in the unmodified alloy quenched before the start of the eutectic reaction. Strontium modified semi-solid Al-7Si-0.3Mg castings were produced and the type of intermetallic phase, morphology, size, area fraction and distribution were similar to that observed in the strontium modified alloy quenched before the start of the Al-Si eutectic reaction.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Aluminum alloys, Cooling, Eutectics, Intermetallics, Iron, Magnesium alloys, Platelets, Solidification, Strontium alloys, Al-7Si-0.3Mg alloys, Al-Si eutectic, Chinese script, Eutectic cells, Eutectic reactions, Intermetallic phase, Intermetallic phasis, Thin platelets, Silicon alloys
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-45391 (URN)10.1007/s11661-019-05343-5 (DOI)000477997600021 ()2-s2.0-85068741757 (Scopus ID)HOA JTH 2019 (Local ID)HOA JTH 2019 (Archive number)HOA JTH 2019 (OAI)
Funder
Vinnova, 2014-05096
Available from: 2019-07-23 Created: 2019-07-23 Last updated: 2019-08-15Bibliographically approved
Hernando, J. C., Elfsberg, J., Ghassemali, E., Dahle, A. & Diószegi, A. (2019). The effect of coarsening of primary austenite on the ultimate tensile strength of hypoeutectic compacted graphite Fe-C-Si alloys. Scripta Materialia, 168, 33-37
Open this publication in new window or tab >>The effect of coarsening of primary austenite on the ultimate tensile strength of hypoeutectic compacted graphite Fe-C-Si alloys
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2019 (English)In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 168, p. 33-37Article in journal (Refereed) Published
Abstract [en]

The effect of primary austenite morphology on the ultimate tensile strength (UTS) of hypoeutectic compacted graphite Fe-C-Si alloys (CGI) is studied by isothermal coarsening experiments. Secondary dendrite arm spacing (SDAS) and the morphological characteristics related to the surface area of primary austenite, M γ and D ID Hyd , increase with the cube root of coarsening time. UTS decreases linearly with increasing coarseness of primary austenite. The eutectic and eutectoid microstructures are unaffected by the primary austenite morphology. These observations demonstrate the strong influence of primary austenite morphology on the mechanical properties of hypoeutectic CGI alloys.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Coarsening, Compacted graphite iron, Dendrites, Mechanical properties, UTS, Austenite, Dendrites (metallography), Graphite, Morphology, Ostwald ripening, Silicon alloys, Tensile strength, Morphological characteristic, Primary austenite, Secondary dendrite arm spacing, Si alloys, Surface area, Ultimate tensile strength, Iron alloys
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-43550 (URN)10.1016/j.scriptamat.2019.04.010 (DOI)000470798400008 ()2-s2.0-85064563538 (Scopus ID)PP JTH 2019 embargo 24 (Local ID)PP JTH 2019 embargo 24 (Archive number)PP JTH 2019 embargo 24 (OAI)
Funder
Vinnova, 2013-03303; 2013-04720Knowledge Foundation, 2018-0033
Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-08-06Bibliographically approved
Bjurenstedt, A., Ghassemali, E., Seifeddine, S. & Dahle, A. (2019). The effect of Fe-rich intermetallics on crack initiation in cast aluminium: an in-situ tensile study. Materials Science & Engineering: A, 756, 502-507
Open this publication in new window or tab >>The effect of Fe-rich intermetallics on crack initiation in cast aluminium: an in-situ tensile study
2019 (English)In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 756, p. 502-507Article in journal (Refereed) Published
Abstract [en]

To evaluate the role of Fe-rich intermetallics on crack initiation, two fully modified Al-Si alloys, one containing plate-like β-Fe and the second containing primary α-Fe intermetallics, were investigated by in-situ tensile testing in the scanning electron microscope. In the first alloy, large plate-like β-Fe intermetallics oriented parallel to the test direction were the first to crack at an elongation of about 1.8%. More transversely oriented intermetallics caused crack initiation in the matrix which linked up with the final fracture. In the second alloy, the cracking of α-Fe intermetallics initiated at an elongation of about 0.9%. It is concluded that large α-Fe intermetallics crack first and that clusters of α-Fe are the most potent crack initiation sites.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Al-Si alloy, Cast aluminium, Fracture mechanics, Tensile testing in SEM, α-Fe, β-Fe, Aluminum alloys, Crack initiation, Cracks, Fracture testing, Intermetallics, Materials testing apparatus, Metal testing, Scanning electron microscopy, Silicon alloys, Tensile testing
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-36962 (URN)10.1016/j.msea.2018.07.044 (DOI)000469893400058 ()2-s2.0-85064717473 (Scopus ID)
Available from: 2017-08-21 Created: 2017-08-21 Last updated: 2019-06-20Bibliographically approved
Olofsson, J., Salomonsson, K., Dahle, A. & Mathiesen, R. H. (2019). Three-dimensional study of nodule clustering and heterogeneous strain localization for tailored material properties in ductile iron. In: IOP Conference Series: Materials Science and Engineering. Paper presented at Joint 5th International Conference on Advances in Solidification Processes, ICASP 2019 and 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining, CSSCR 2019, 17-21 June 2019. Institute of Physics (IOP), 529(1), Article ID 012078.
Open this publication in new window or tab >>Three-dimensional study of nodule clustering and heterogeneous strain localization for tailored material properties in ductile iron
2019 (English)In: IOP Conference Series: Materials Science and Engineering, Institute of Physics (IOP), 2019, Vol. 529, no 1, article id 012078Conference paper, Published paper (Refereed)
Abstract [en]

Tailored heterogeneous distributions of microstructural features enable extraordinary material performance in biological and physiological structures such as trees, the aortic arch, human teeth and dinosaur skulls. In ductile iron, a heterogeneous distribution in size and morphology of graphite nodules and variations of the fractions of ferrite and pearlite are created during solidification, and varies as a function of parameters such as local cooling rate, segregation and flow. In the current work, the size distribution as well as the orientation and relation between graphite nodules is obtained by a three-dimensional reconstruction of a ductile iron microstructure from X-ray tomography. The effect of the nodule morphology and clustering on the localization of plastic strains is studied numerically using finite element analysis of the reconstructed microstructure. Real castings have a variation in geometry, solidification conditions and are subjected to variations in loads. A framework for optimized geometry and solidification conditions in order to design and deliver castings with tailored local material performance is proposed.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2019
Series
IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981 ; 529:1
Keywords
Biological materials, Cutting tools, Ductility, Graphite, Iron, Microstructure, Morphology, Refining, Strain, Heterogeneous distributions, Heterogeneous strain, Material performance, Microstructural features, Optimized geometries, Physiological structures, Solidification condition, Three-dimensional reconstruction, Solidification
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-45336 (URN)10.1088/1757-899X/529/1/012078 (DOI)2-s2.0-85067865845 (Scopus ID)
Conference
Joint 5th International Conference on Advances in Solidification Processes, ICASP 2019 and 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining, CSSCR 2019, 17-21 June 2019
Available from: 2019-07-12 Created: 2019-07-12 Last updated: 2019-07-12Bibliographically approved
Santos, J., Jarfors, A. E. .. & Dahle, A. (2019). Variation of properties in the cross-section of semi-solid al-7si-0.3mg castings. In: Rassili A.,Midson S.P.,Zhu Q.,Gang Hu X. (Ed.), Semi-Solid of Alloys and Composites: . Paper presented at 15th International conference on Semi-Solid Processing of Alloys and Composites, S2P 2018; Shenzhen; China; 22 - 24 October 2018 (pp. 81-86). Trans Tech Publications
Open this publication in new window or tab >>Variation of properties in the cross-section of semi-solid al-7si-0.3mg castings
2019 (English)In: Semi-Solid of Alloys and Composites / [ed] Rassili A.,Midson S.P.,Zhu Q.,Gang Hu X., Trans Tech Publications, 2019, p. 81-86Conference paper, Published paper (Refereed)
Abstract [en]

In semi-solid casting, a slurry consisting of primary α-Al crystals and liquid is injected into the die cavity. The solidification in the die-cavity occurs by the growth of the primary α-Al crystals formed during slurry preparation and in the shot sleeve, nucleation and growth of in-cavity solidified crystals and ends with the eutectic reaction. During solidification in the die cavity, the cooling rate near the die wall is higher in comparison to the centre of the casting, particularly for thick-walled castings. The solidification conditions for the slurry α-Al crystals that are closer to the die wall can be very different compared to the slurry α-Al crystals located at the casting centre. This can result in different solute concentration in the interior of the α-Al globules in different regions of the semi-solid casting cross-section and consequently, different response to heat treatament. The RheoMetal™ process was used to produce thick-walled semi-solid castings. Semi-solid castings in the as-cast and T6 conditions were investigated. Indentation tests for hardness measurements in the nano-range were performed in the interior of α-Al globules near the surface and at the casting cross-section centre. The hardness variation across the casting cross-section was evaluated by low-force Vickers hardness. The castings in the as-cast condition showed more uniform properties in the cross-section compared to the T6 condition. Additionally, the results suggest that microsegregation in the interior of α-Al globules is very low in castings in the as-cast and T6 conditions. 

Place, publisher, year, edition, pages
Trans Tech Publications, 2019
Series
Science, University and Society, ISSN 1653-6010
Series
Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779 ; 285
Keywords
Hardness, Heat treatment, Properties, Rheometal™, Semi-solid casting, Die casting machines, Dies, Vickers hardness, Eutectic reactions, Hardness measurement, Hardness variation, Nucleation and growth, Semi solid casting, Solidification condition, Solute concentrations, Solidification
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-42786 (URN)10.4028/www.scientific.net/SSP.285.81 (DOI)2-s2.0-85059953796 (Scopus ID)9783035713732 (ISBN)9783035733730 (ISBN)
Conference
15th International conference on Semi-Solid Processing of Alloys and Composites, S2P 2018; Shenzhen; China; 22 - 24 October 2018
Available from: 2019-01-31 Created: 2019-01-31 Last updated: 2019-01-31Bibliographically approved
Bogdanoff, T., Dahle, A. K. & Seifeddine, S. (2018). Effect of Co and Ni Addition on the Microstructure and Mechanical Properties at Room and Elevated Temperature of an Al–7%Si Alloy. International Journal of metalcasting, 12(3), 434-440
Open this publication in new window or tab >>Effect of Co and Ni Addition on the Microstructure and Mechanical Properties at Room and Elevated Temperature of an Al–7%Si Alloy
2018 (English)In: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 12, no 3, p. 434-440Article in journal (Refereed) Published
Abstract [en]

Increasing environmental demands are forcing the automotive industry to reduce vehicle emissions by producing more light-weight and fuel efficient vehicles. Al–Si alloys are commonly used in automotive applications because of excellent castability, high thermal conductivity, good wear properties and high strength-to-weight ratio. However, most of the aluminium alloys on the market exhibit significantly reduced strength at temperatures above 200 °C. This paper presents results of a study of the effects of Co and Ni in a hypoeutectic Al–Si alloy on microstructure and mechanical properties at room and elevated temperature. Tensile test specimens with microstructures comparable to those obtained in high-pressure die casting, i.e. SDAS ~ 10 µm, were produced by directional solidification in a Bridgman furnace. The results show an improvement in tensile properties up to 230 °C.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Al–Si alloy, mechanical properties, cobalt, nickel, elevated temperature
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-37539 (URN)10.1007/s40962-017-0178-z (DOI)000436927100004 ()2-s2.0-85049356111 (Scopus ID)
Available from: 2017-10-03 Created: 2017-10-03 Last updated: 2019-02-05Bibliographically approved
Santos, J., Kallien, L. H., Jarfors, A. E. .. & Dahle, A. (2018). Influence of grain refinement on slurry formation and surface segregation in semi-solid Al-7Si-0.3Mg castings. Metallurgical and Materials Transactions. A, 49A(10), 4871-4883
Open this publication in new window or tab >>Influence of grain refinement on slurry formation and surface segregation in semi-solid Al-7Si-0.3Mg castings
2018 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 49A, no 10, p. 4871-4883Article in journal (Refereed) Published
Abstract [en]

This study aims to evaluate the effect of grain refinement on slurry formation and surface segregation in semi-solid castings produced by the Rheometal™ process. The effect of two grain refiners, Al-8B and Al-5Ti-1B, on the slurry α-Al grain size, shape factor and solid fraction was evaluated. The results suggest that the addition of a grain refiner can affect the solid fraction obtained in the RheometalTM process and, consequently, reduce the solute content near the casting surface. Grain refiner addition resulted in a larger fraction of α-Al grains ≤ 60 µm for the refined alloys compared with the unrefined alloy. Additionally, the growth of α-Al slurry globules was greater for the unrefined alloy compared with the refined alloy during solidification in the die-cavity. A more homogeneous and finer microstructure was observed near the surface in the grain-refined castings compared with the unrefined castings. Evidence of significant liquid penetration was identified in some α-Al globules, indicating that disintegration of α-Al globules may occur during the Rheometal™ casting process.

Place, publisher, year, edition, pages
Springer, 2018
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-38689 (URN)10.1007/s11661-018-4787-9 (DOI)000443469700048 ()2-s2.0-85049646113 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Note

Included in thesis in manuscript form with title: Influence of grain refinement on slurry formation and surface segregation in Al‐7Si‐0.3Mg semi‐solid castings

Available from: 2018-01-30 Created: 2018-01-30 Last updated: 2018-09-13Bibliographically approved
Ceschini, L., Dahle, A., Gupta, M., Jarfors, A. E. .., Jayalakshmi, S., Morri, A., . . . Singh, R. A. (2017). Aluminum and Magnesium Metal Matrix Nanocomposites. Springer
Open this publication in new window or tab >>Aluminum and Magnesium Metal Matrix Nanocomposites
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2017 (English)Book (Other academic)
Abstract [en]

The book looks into the recent advances in the ex-situ production routes and properties of aluminum and magnesium based metal matrix nanocomposites (MMNCs), produced either by liquid or semi-solid state methods. It comprehensively summarizes work done in the last 10 years including the mechanical properties of different matrix/nanoreinforcement systems. The book also addresses future research direction, steps taken and missing developments to achieve the full industrial exploitation of such composites. The content of the book appeals to researchers and industrial practitioners in the area of materials development for metal matrix nanocomposites and its applications.

Place, publisher, year, edition, pages
Springer, 2017. p. 164
Series
Engineering Materials, ISSN 1612-1317, E-ISSN 1868-1212
Keywords
Metal Matrix Nanocomposites (MMNCs) Stir Casting Compocasting Ultrasonic assisted casting Disintegrated melt deposition Liquid State Processes Solid State Processes Semi-solid State Processes Nanocomposites Strengthening Mechanisms Ex-situ Production Methods
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-38236 (URN)10.1007/978-981-10-2681-2 (DOI)000401722400001 ()978-981-10-2680-5 (ISBN)978-981-10-2681-2 (ISBN)
Available from: 2017-12-19 Created: 2017-12-19 Last updated: 2018-09-21Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3184-7592

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