miun.sePublications
Change search
Refine search result
1 - 8 of 8
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Razaz, Ghadir
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Investigation of the Drawbacks in the Aluminium Alloys Casting Process2017Licentiate thesis, comprehensive summary (Other academic)
  • 2.
    Razaz, Ghadir
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Problems in the Aluminium DC Casting Process Associated with Melt Treatment Operations2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The quality of DC cast Al alloys is highly dependent on melt batch composition and impurity level in the molten alloy. The chemical composition and cleanliness of a melt is controlled through the melt treatment operations, carried out while the melt is still in the furnace before casting starts. The present work has studied some of these operations and associated problems such as slow dissolution of alloying elements, non-reproducibility in chemical composition analysis and inclusions.

     The results of the dissolution of the alloy elements Mn and Fe showed different behaviors.  For Mn three intermediate phases were involved, 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 towards the dissolving Mn particles. The results from the Fe dissolution revealed that only one phase dominates the process, Al5Fe2, which penetrates the Fe particles with an irregular interface.

    The interaction between Mn and Ti additions to AA3003 alloys and consequences for the solidification and precipitation behavior was investigated. The study could map the limits for formation of an earlier unknown AlMnTi phase, which formed large particles, detrimental for subsequent rolling operations.

    Different sampling procedures for chemical composition analysis were studied, and a novel approach was proposed. A mould with an insulated periphery provided one-dimensional solidification, which gave compositions close to nominal.

     Inclusion distributions along as-cast billets were studied as a function of different holding times, and thus different grades of sedimentation. Holding times longer than 30 minutes did not show any improvements.  It was also shown that if melt remaining in the furnace at end of casting is less than about 3000 kg, the sedimented inclusions are stirred into the bulk again, and can enter into the end of the billet.

    The impact on hot tearing susceptibility of different Cu and Fe contents for AA3000 alloys was studied. Cu contents in a range from 0.3 to 1.2 wt%  significantly increase the hot tearing tendency, which was attributed to bad feeding at end of solidification. Decreasing of the Fe content below 0.2 wt%, gives a strong cracking tendency, owing to decreased precipitations of the Al6(Mn,Fe) phase, which contributes to early bridging and thus reinforcement between grains.

  • 3.
    Razaz, Ghadir
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Carlberg, Torbjörn
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Casting practices influencing inclusion distributions in billets2013In: Light Metals, ISSN 0147-0809, p. 987-991Article in journal (Refereed)
    Abstract [en]

    A macro-etching method has been used to analyze the distribution and amount of inclusions along billets and on cross sections. Main parameters that have been varied are holding time before casting and amount of liquid remaining after casting. The result show that short holding times, in the order of 10 minutes, give increased amount of inclusions in the beginning of the billets, but holding times in the range from 30 to 60 minutes do not show any significant differences. If the melt remaining in the furnace after casting is less than about 3000 kg, the inclusion density increases towards the end of the ingots. The distribution of inclusions over the cross section of billets show that most inclusions are found in the centre of the billets, however, at increased total amount of inclusions, they tend to appear evenly over the whole cross sections. The results are discussed based on convection in furnace and settling rates and convection at solidification front.

  • 4.
    Razaz, Ghadir
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Carlberg, Torbjörn
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Hot tearing susceptibility of AA3000 aluminum alloy containing Cu, Ti, and Zr2019In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 50A, no 8, p. 3842-3854Article in journal (Refereed)
    Abstract [en]

    Severe hot tearing has been observed during DC casting of modified AA3000 alloys with additions of Cu, Ti, and Zr, although these alloys are regarded as rather easy to cast. Extensive studies have been performed on both synthetic and industrial AA2000, AA6000, and AA7000 alloys, but less data are available for AA3000 alloys. This work was thus initiated to investigate the hot tearing susceptibility of AA3000 alloys with varying alloy element content using constrained rod casting molds. The results showed that the Cu and Fe content have a major impact on hot tearing resistance, while the effects of Zr and Ti are minor. Cu in a range from 0.3 to 1.2 wt pct significantly increased the hot tearing tendency. This is due to the existence of high eutectic fractions at low temperatures, as well as porosity formation associated with bad feeding at the end of solidification. A strong cracking tendency was observed below an Fe content 0.2 wt pct owing to decreased precipitation of the Al6(Mn, Fe) phase. It was found that primary Al6(Mn, Fe) phases lead to early bridging between the grains, which reinforces the alloy during the vulnerable temperature range for hot tearing. Zr and Ti additions weakly enhanced or reduced hot tearing severity, respectively.

  • 5.
    Razaz, Ghadir
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Carlberg, Torbjörn
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    On the dissolution Process of Manganese and Iron in Molten Aluminum2019In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 50, no 4, p. 1873-1887Article in journal (Refereed)
    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.

  • 6.
    Razaz, Ghadir
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Carlberg, Torbjörn
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Segregation during metal sampling2014In: Materials science forum, Trans Tech Publications Inc., 2014, p. 83-88Conference paper (Refereed)
    Abstract [en]

    In order to obtain accurate chemical compositions in as-cast billets and ingots the sampling methods for the analysis have to give reproducible results with high precision. OES analysis made on samples at certain milling depths does not always show the desired nominal composition, and especially the macro segregation profiles within the samples can show significant variations. The present work examine the influence of main sampling parameters, such as the volume of the melt, the melt temperature, the mould design and the method of filling the mould, on the segregation. The results point out the importance of the convection in the mould during solidification, and thus the technique of pouring the melt into the sampling mould. © (2014) Trans Tech Publications, Switzerland.

  • 7.
    Razaz, Ghadir
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Carlberg, Torbjörn
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Solidification studies of 3003 alloys with different Mn and Ti contents2017In: 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 (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.

  • 8.
    Razaz, Ghadir
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Carlberg, Torbjörn
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Study of manganese dissolution in aluminum melts2016In: TMS Light Metals, Minerals, Metals & Materials Society, 2016, p. 731-736Conference 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.

1 - 8 of 8
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf