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Bayat, N., Carlberg, T. & Cieslar, M. (2019). In-Situ Study of Phase Transformations during Homogenization of 6060 and 6063 Al Alloys. Journal of Physics and Chemistry of Solids, 130, 165-171
Open this publication in new window or tab >>In-Situ Study of Phase Transformations during Homogenization of 6060 and 6063 Al Alloys
2019 (English)In: Journal of Physics and Chemistry of Solids, ISSN 0022-3697, E-ISSN 1879-2553, Vol. 130, p. 165-171Article in journal (Refereed) Published
National Category
Materials Engineering
Identifiers
urn:nbn:se:miun:diva-30011 (URN)10.1016/j.jpcs.2018.11.013 (DOI)2-s2.0-85062641742 (Scopus ID)
Available from: 2017-02-08 Created: 2017-02-08 Last updated: 2019-03-25Bibliographically approved
Razaz, G. & Carlberg, T. (2019). On the dissolution Process of Manganese and Iron in Molten Aluminum. Metallurgical and Materials Transactions. A, 50(4), 1873-1887
Open this publication in new window or tab >>On the dissolution Process of Manganese and Iron in Molten Aluminum
2019 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 50, no 4, p. 1873-1887Article in journal (Refereed) Published
Abstract [en]

The dissolution of Mn and Fe in liquid Al presents a challenge due to their high melting points and low diffusivity. A literature review reveals that the existing knowledge of the processes involved in the dissolution of both Fe and Mn in liquid Al is rather ambiguous. Thus, this work aimed to obtain more detailed insights into the dissolution behavior of Mn and Fe in various Al melts. The results of the Mn dissolution tests showed that three intermediate phases were involved in the dissolution process, all of which exhibited a smooth interface between Mn and the liquid. These three phases were identified as the γ2, Al11Mn4, and µ phases which grow slowly, penetrating the Mn particles. The results of the Fe dissolution tests showed that in pure Al, the Al5Fe2 phase dominates the dissolution process and penetrates the Fe particles. The addition of Ti into the molten Al alters the intermetallic compound formation by replacing Al5Fe2 by Al2Fe. The addition of Si significantly inhibited the Fe dissolution kinetics. A theoretical approach based on Ficks’ law was used to explain the experimentally obtained Mn and Fe dissolution rates. It showed that the surface area and shape of the additives significantly affected the dissolution processes.

Place, publisher, year, edition, pages
Springer, 2019
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:miun:diva-35502 (URN)10.1007/s11661-019-05120-4 (DOI)000459814000026 ()2-s2.0-85060143392 (Scopus ID)
Available from: 2019-01-21 Created: 2019-01-21 Last updated: 2019-04-04Bibliographically approved
Bayat, N. & Carlberg, T. (2017). Influence of Heat Treatment on the Surface Structure of 6082 Al Alloys. Metallurgical and Materials Transactions. A, 48A(10), 5085-5094
Open this publication in new window or tab >>Influence of Heat Treatment on the Surface Structure of 6082 Al Alloys
2017 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 48A, no 10, p. 5085-5094Article in journal (Other academic) Published
Abstract [en]

The β-Al5FeSi intermetallic phase and coarse Mg2Si particles have negative effects on extrudability and workability of 6xxx Al alloys billets. To achieve extruded products with a high surface quality, the as-cast billets are heat-treated before extrusion. During heat treatment, the undesired intermetallic particles, i.e., β-AlFeSi platelets are transformed to rounded α-Al(FeMn)Si intermetallic phases. Although the heat treatment of the bulk areas of the 6xxx Al alloys has been the focus of many previous studies, the process of phase transformation at the very surface has not been paid the same attention. In this study, microstructures of a homogenized billet of a 6082 alloy at the area very close to the surface were investigated. By comparing the X-ray diffraction patterns (XRD) of heat-treated samples as a function of different holding times, the gradual phase transformations could be followed, and using GDOES and map analysis by EDX, the alloying elemental redistribution was analyzed. Partial remelting and porosity growth was detected, and transformation rates were faster than in bulk material and from what is known from industrial processes.

National Category
Materials Engineering
Identifiers
urn:nbn:se:miun:diva-30009 (URN)10.1007/s11661-017-4207-6 (DOI)000408884300058 ()2-s2.0-85025633715 (Scopus ID)
Available from: 2017-02-08 Created: 2017-02-08 Last updated: 2017-12-18Bibliographically approved
Bayat, N., Carlberg, T. & Cieslar, M. (2017). In-Situ Study of Phase Transformations during Homogenization of 6005 and 6082 Al Alloys. Journal of Alloys and Compounds, 725, 504-509
Open this publication in new window or tab >>In-Situ Study of Phase Transformations during Homogenization of 6005 and 6082 Al Alloys
2017 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 725, p. 504-509Article in journal (Refereed) Published
Abstract [en]

Intermetallic β-Al5FeSi phase and coarse Mg2Si particles have negative effects on extrudability and workability of 6xxx Al alloy billets. To achieve extruded products with a high surface quality as-cast billets are therefore heat-treated before extrusion. During heat treatment the undesired intermetallic particles, i.e., β-AlFeSi platelets, are transformed to a rounded α-Al(FeMn)Si intermetallic phase. This transformation was studied in-situ by TEM for 6005 and 6082 Al alloys. It was observed that the Mg2Si particles precipitate in the Al matrix at about 250 °C; this precipitation also occurred at the edge and faces of beta intermetallic particles, and the Mg2Si particles were the preferred sites for α-Al(FeMn)Si particle nucleation. The transformation proceeded faster and at lower temperatures, 350–450 °C, than what has been reported earlier for homogenization studies of bulk samples and industrial billets. This could be associated with the thin characteristic of used samples in TEM giving contribution from fast surface diffusion, but it was also concluded that the phase boundary layer diffusion was important for the understanding of how the transformations proceed.

Keywords
6xxx Al alloys, Heat treatment, Homogenization, In-situ TEM, Phase transformation
National Category
Materials Engineering
Identifiers
urn:nbn:se:miun:diva-30010 (URN)10.1016/j.jallcom.2017.07.149 (DOI)000412332900058 ()2-s2.0-85025668240 (Scopus ID)
Note

The Mid Sweden University is acknowledged for financial support, and Kubikenborg Aluminium AB is acknowledged for providing materials.

Available from: 2017-02-08 Created: 2017-02-08 Last updated: 2017-12-12Bibliographically approved
Razaz, G. & Carlberg, T. (2017). Solidification studies of 3003 alloys with different Mn and Ti contents. In: Fan, Zhongyun (Ed.), Solidification processing 2017: proceedings of the 6th Decennial International Conference on Solidification Processing : 25-28 July 2017, Beaumont Estate, Old Windsor, UK. Paper presented at 6th Decennial international conference , 25-28 July 2017, old Windsor, UK. bcast
Open this publication in new window or tab >>Solidification studies of 3003 alloys with different Mn and Ti contents
2017 (English)In: Solidification processing 2017: proceedings of the 6th Decennial International Conference on Solidification Processing : 25-28 July 2017, Beaumont Estate, Old Windsor, UK / [ed] Fan, Zhongyun, bcast , 2017Conference paper, Published paper (Refereed)
Abstract [en]

Aluminum alloys of AA3003 are widely used in heat exchangers. This type of alloy mainly contains manganese as alloying element, but in recent developments there have been additions of both titanium and copper. The limits of Mn solubility in aluminum are influenced by these additions, which can cause the formation of large particles of an unwanted AlMnTi phase.

This project was initiated to investigate the effects of Mn contents in combination with Ti additions on the solidification and precipitation behavior using both Bridgman directional solidification and DTA equipment. The results show that coarse AlMnTi particles start forming when Mn contents are over 1.5 wt% in alloys with 0.14 wt% Ti and that the amount significantly increases with increasing Mn content from this level. Large particles were also found for Mn contents slightly below 1.4 wt%. If the Ti additions were on the level of 0.25 wt%. The DTA experiments show that AlMnTi phases grow in a limited temperature interval, and can reach a size of 150 microns. Such large sized particles are detrimental for the material in the ensuing rolling operation and must be avoided, and it is, therefore, important to accurately control the combinations of Mn and Ti contents.

Place, publisher, year, edition, pages
bcast, 2017
Keywords
Bridgman Technique, Differential Thermal Analysis, 3003 Alloy, Intermetallic Particles
National Category
Natural Sciences Materials Engineering
Identifiers
urn:nbn:se:miun:diva-35020 (URN)9781908549297 (ISBN)
Conference
6th Decennial international conference , 25-28 July 2017, old Windsor, UK
Available from: 2018-12-03 Created: 2018-12-03 Last updated: 2019-04-04Bibliographically approved
Saleem, J., Majid, A., Malik, A. W., Bertilsson, K. & Carlberg, T. (2016). An efficient method of spot welding Aluminium alloys with induction preheating. Journal of Electrical Systems, 12(4), 817-825
Open this publication in new window or tab >>An efficient method of spot welding Aluminium alloys with induction preheating
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2016 (English)In: Journal of Electrical Systems, ISSN 1112-5209, Vol. 12, no 4, p. 817-825Article in journal (Refereed) Published
Abstract [en]

Steel has been the material of choice for automobile manufacturers. In the recent years material such as aluminium and its alloys are taking over the market because of their light weight. The use of aluminium, in automobile manufacturing can result in overall fuel efficiency. Spot welding aluminium alloys require higher electric power and less welding time as compared to steel. Welding guns that can produce an electric current which is approximately 2 to 3 times higher, as compared to steel are required for spot welding aluminium. An efficient method of spot welding Aluminium alloys with the preheating process has been proposed in this paper. Preheating Aluminium sheet before spot welding reduces the thermal and electrical resistance which brings down the electric current requirement to spot weld Aluminium structures. Both spot welding and induction preheating process have been modelled in this paper. The test results of the preheating process have also been verified with practical heating trials. The preheating is performed on-the-fly in advance to spot welding process. The results show that spot welding Al 6082 after preheating up to 200 degrees C, the output current requirements to make the spot weld are reduced by 22%..

Keywords
Finite element method, pre heating, resistance spot welding, induction heating, aluminium welding
National Category
Materials Engineering
Identifiers
urn:nbn:se:miun:diva-30095 (URN)000391139200013 ()2-s2.0-85010727858 (Scopus ID)
Available from: 2017-02-10 Created: 2017-02-10 Last updated: 2017-08-08Bibliographically approved
Engstrand, P., Gradin, P., Hellström, L., Carlberg, T., Sandström, P., Liden, J., . . . Mats, E. (2016). Improved refining energy efficiency in thermo-mechanical pulping by means of collimated wood chipping – from solid mechanics to full scale evaluation. In: Greg Hay (Ed.), PaperWeek Canada 2016 Conference February 1 to 5, 2016, Montreal: Technical Track Program. Paper presented at PaperWeek Canada 2016 Conference, Montreal, February 1-5, 2016.
Open this publication in new window or tab >>Improved refining energy efficiency in thermo-mechanical pulping by means of collimated wood chipping – from solid mechanics to full scale evaluation
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2016 (English)In: PaperWeek Canada 2016 Conference February 1 to 5, 2016, Montreal: Technical Track Program / [ed] Greg Hay, 2016Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

The wood chipping process was never optimized with regard to high yield pulping processes as thermomechanical pulping (TMP) and chemithermomechanical pulping (CTMP). It is generally believed that wood chips for pulping should be produced in such a way that the degree of damage is minimized and that the chip dimensional distribution should be as narrow as possible. Since the TMP and CTMP processes were developed in the 60-ies and 70-ies, compression screw as well as roll nip equipment have been developed to pretreat wood chips as a way to reduce refining energy consumption to given fiber and pulp properties and also in order to improve impregnation. The general conclusions are that a combination of shear and compression in the tangential or radial direction of the wood initiates cracks that later in the refiner will enhance and optimize fiber separation and also fiber property development. The idea with the collimated chipping technology is to utilize the wood chipper as a tool, combining cutting of wood logs to wood chips with a pretreatment of the chips by creating cracks that would enhance fiber separation, fiber surface development as well as chip-impregnation. In this case the compression is performed in the wood fiber direction, in which direction wood actually is weakest when it comes to compression induced cracking. The maximization of the amount of cracks in wood-chips is performed by optimizing the knife angle (or spout angle) in the chipper, to what we call collimated chipping (according to a patent owned by CCT AB). This presentation describes a theoretical background and two demonstration scale studies performed by SCA Forest Products at their Ortviken mill. One conclusion drawn, based on two-month test period with three weeks of collimated chipping, was that specific refining energy reduction was around 100 kWh/adt of the 1400 kWh/adt used in primary stage double disc refining. Most probably the potential is higher if the whole system is optimized. Tests were performed at constant production rate and energy was reduced by reducing power to constant freeness, leading to similar tensile and light scattering levels. The deliberately increased forces created in the wood chipper by means of an optimized (increased) edge angle caused more problems with knife holder equipment than normally, as well as increased vibrations. These problems will have to be solved for future long-term implementation of the technique.

Keywords
chipping, mechanical pulping, energy reduction
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:miun:diva-29474 (URN)
Conference
PaperWeek Canada 2016 Conference, Montreal, February 1-5, 2016
Projects
e2mp forskningsprofil
Funder
Knowledge Foundation, 2010/0178VINNOVA, 2012-00786
Available from: 2016-12-07 Created: 2016-12-07 Last updated: 2017-02-07Bibliographically approved
Razaz, G. & Carlberg, T. (2016). Study of manganese dissolution in aluminum melts. In: TMS Light Metals: . Paper presented at Light Metals 2016 - TMS 2016: 145th Annual Meeting and Exhibition; Music City Center, Nashville; United States; 14 February 2016 through 18 February 2016; Code 121631 (pp. 731-736). Minerals, Metals & Materials Society
Open this publication in new window or tab >>Study of manganese dissolution in aluminum melts
2016 (English)In: TMS Light Metals, Minerals, Metals & Materials Society, 2016, p. 731-736Conference paper, Published paper (Refereed)
Abstract [en]

Problems with the yield during Mn alloy additions and the occurrence of undissolved Mn rich phases in as cast material containing Ti is the background to the present study of the dissolution of Mn compacts in aluminum melts. The dissolution rate of Mn in liquid aluminum, have been studied in pure Al and in Al-0.12%Ti melts. It was found that Ti additions to the melt decreased the dissolution rate of Mn compacts. It was also shown that the intermediate phases formed at the interface between Mn and liquid aluminum was different after small Ti additions. Moreover, an undissolved Mn briquette, found after casting in a furnace, was examined and the conditions for this to happen have been discussed. The discussion was based on calculations of heat balances during the initial dissolution steps and studies of the transformations occurring within the briquette.

Place, publisher, year, edition, pages
Minerals, Metals & Materials Society, 2016
Keywords
Dissolution rate, Freeze-on layer, Heat transportation, Intermetallic phases, Manganese briquette
National Category
Materials Engineering
Identifiers
urn:nbn:se:miun:diva-28496 (URN)2-s2.0-84974604002 (Scopus ID)9781119225799 (ISBN)
Conference
Light Metals 2016 - TMS 2016: 145th Annual Meeting and Exhibition; Music City Center, Nashville; United States; 14 February 2016 through 18 February 2016; Code 121631
Note

Scopus ID for book chapter: 2-s2.0-84982238790

Available from: 2016-07-22 Created: 2016-07-21 Last updated: 2019-04-04Bibliographically approved
Bayat, N. & Carlberg, T. (2016). Surface formation in direct chill (DC) casting of 6082 aluminium alloys. In: IOP Conference Series: Materials Science and Engineering. Paper presented at 4th International Conference on Advances in Solidification Processes, ICASP 2014, 8 July 2014 through 11 July 2014. Institute of Physics Publishing (IOPP), 117(1), Article ID 012038.
Open this publication in new window or tab >>Surface formation in direct chill (DC) casting of 6082 aluminium alloys
2016 (English)In: IOP Conference Series: Materials Science and Engineering, Institute of Physics Publishing (IOPP), 2016, Vol. 117, no 1, article id 012038Conference paper, Published paper (Refereed)
Abstract [en]

Surface defects in aluminium billet production are a real problem for the subsequent extrusion procedure. Extrusion productivity can be influenced by the surface properties, which is defined as surface appearance, surface segregation zone depth and large Mg2Si and β-particles (Al5FeSi). In this research the surface formation during DC casting of 6082 aluminium billets produced by the air slip technology is studied. The surface microstructures of 6082 aluminium alloys with smooth and wavy surface appearances were investigated, including segregation zone depths and phase formation. The results were discussed based on the exudation of liquid metal through the mushy zone. The specific appearance of the wavy surface of 6082 alloys was correlated to how the oxide skin adheres to the underlying mushy zone and coupled to the dendritic coherency and surface tension of the skin. The occurrence of different phases at the very surface and in the layer just below was explained by variations in solidification directions and subsequent segregation patterns.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2016
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-29685 (URN)10.1088/1757-899X/117/1/012038 (DOI)2-s2.0-84968853364 (Scopus ID)
Conference
4th International Conference on Advances in Solidification Processes, ICASP 2014, 8 July 2014 through 11 July 2014
Note

Conference Paper

Available from: 2016-12-19 Created: 2016-12-19 Last updated: 2017-02-08Bibliographically approved
Bayat, N. & Carlberg, T. (2015). On Liquid Metal Wetting of Casting Rings for DC Casting. In: Margaret Hyland (Ed.), TMS Light Metals: . Paper presented at Light Metals 2015 - TMS 2015 Annual Meeting and Exhibition; Walt Disney WorldOrlando; United States; 15 March 2015 through 19 March 2015; Code 113955 (pp. 859-864). Warrendale: Minerals, Metals & Materials Society, 2015-January
Open this publication in new window or tab >>On Liquid Metal Wetting of Casting Rings for DC Casting
2015 (English)In: TMS Light Metals / [ed] Margaret Hyland, Warrendale: Minerals, Metals & Materials Society, 2015, Vol. 2015-January, p. 859-864Conference paper, Published paper (Refereed)
Abstract [en]

During air–slip direct chill casting of aluminum alloys, uneven or low air pressure areas at the surface of the porous graphite ring mold, can cause the metal to stick to the graphite ring and produce traces along the billets called vertical drags (VD). To prevent this type of defect, it would be an advantage to decrease the wettability of the graphite ring.  It has been shown that nanostructured surfaces can have hydrophobic properties, and a question is weather the same effect can be achieved for molten metals. A TiO2 nanowire structure is proposed to cover the casting ring, and the wetting behavior of such a structure has been studied, and compared to the wetting at a regular graphite ring surface by the dispensed sessile drop method. The results showed that the nanostructured surface very strongly dewetting metal droplets.

Place, publisher, year, edition, pages
Warrendale: Minerals, Metals & Materials Society, 2015
Series
TMS Light Metals, ISSN 0147-0809
Keywords
DC Casting, Wetting, Casting ring, Aluminium
National Category
Engineering and Technology
Identifiers
urn:nbn:se:miun:diva-26338 (URN)2-s2.0-84942925150 (Scopus ID)9781119082446 (ISBN)
Conference
Light Metals 2015 - TMS 2015 Annual Meeting and Exhibition; Walt Disney WorldOrlando; United States; 15 March 2015 through 19 March 2015; Code 113955
Funder
Knowledge Foundation
Available from: 2015-12-01 Created: 2015-12-01 Last updated: 2017-02-08Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3622-4247

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