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    Overview - Talha Nibras Ali (62646)

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    Talha Nibras Ali
    The document discusses the formation of nodular graphite in cast iron through magnesium treatment. [1] Adding at least 0.04% magnesium to molten cast iron causes the graphite to form spherical nodules rather than flakes during solidification. [2] This occurs as the magnesium gas bubbles act as nucleation sites for the graphite, forming nodules that enhance strength and toughness over flake graphite. [3] The nodular graphite can then be obtained directly from the melt without further heat treatment, unlike malleable iron production.

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    Overview - Talha Nibras Ali (62646)

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    Talha Nibras Ali
    16 views2 pages
    The document discusses the formation of nodular graphite in cast iron through magnesium treatment. [1] Adding at least 0.04% magnesium to molten cast iron causes the graphite to form spherical nodules rather than flakes during solidification. [2] This occurs as the magnesium gas bubbles act as nucleation sites for the graphite, forming nodules that enhance strength and toughness over flake graphite. [3] The nodular graphite can then be obtained directly from the melt without further heat treatment, unlike malleable iron production.

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    Overview- Talha Nibras Ali (62646)

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    The document discusses the formation of nodular graphite in cast iron through magnesium treatment. [1] Adding at least 0.04% magnesium to molten cast iron causes the graphite to form spherical nodules rather than flakes during solidification. [2] This occurs as the magnesium gas bubbles act as nucleation sites for the graphite, forming nodules that enhance strength and toughness over flake graphite. [3] The nodular graphite can then be obtained directly from the melt without further heat treatment, unlike malleable iron production.

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    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    16 views2 pages

    Overview - Talha Nibras Ali (62646)

    Uploaded by

    Talha Nibras Ali
    The document discusses the formation of nodular graphite in cast iron through magnesium treatment. [1] Adding at least 0.04% magnesium to molten cast iron causes the graphite to form spherical nodules rather than flakes during solidification. [2] This occurs as the magnesium gas bubbles act as nucleation sites for the graphite, forming nodules that enhance strength and toughness over flake graphite. [3] The nodular graphite can then be obtained directly from the melt without further heat treatment, unlike malleable iron production.

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    of 2

    Influences of the Formation of Cast Iron with Nodular Graphite

    (GJS) using Magnesium Treatment Process.

    In metallurgical analogy Nodular iron can also be termed as Ductile Iron. The Ductile or Cast
    iron is produced by adding magnesium to liquid cast iron to produce a retained magnesium
    content of about 0.04 % or more by weight. When this amount of magnesium is retained the iron
    solidifies with nodular or spherical graphite. The graphite in the cast iron exists as the spherical
    shape or spheroids. This phenomenon occurs when the graphite splits from the molten melt
    during solidification and the reaction of the additives involved. Current views on the mechanism
    of the formation of nodular graphite in cast iron are examined with respect to their explanatory
    power. The formation of these nodules enhances the strength and toughness when compared to
    the gray cast iron. This property helps the nodular cast iron to be widely used in manufacturing
    technologies. The matrixes in which magnesium or rare earth metals are added just before the
    casting process can be any ferrous alloy e.g. pearlite, martensite or austenite. But the latest
    research shows the best results as in case of the nodular graphite by using the bainite matrix.

    Experiments carried out to investigate the nodularizing effect of magnesium in magnesium


    treated cast irons indicates the presence of magnesium gas bubbles in the melt and the pressure
    dependence of the nodularizing effect of magnesium. These results are satisfactorily explained by
    the gas bubble theory and it is clear that magnesium gas bubbles are responsible for the
    nodularization of graphite in cast irons treated with magnesium and its alloys. Hence the graphite
    nodules can be obtained by four methods: addition of deleterious elements such as S, Se, Te, Pb,
    and Bi; or of Ce, La, Y, Ti, and Zr which have absorbed a large amount of hydrogen; direct
    injection of gases into the melts; and precipitation of nitrogen from super-saturated molten cast
    iron.

    It is well known that malleable irons have always been subjected to severe practical limitations
    relating to useful ranges of composition, section size, and the combinations of mechanical,
    physical and chemical properties which could be produced therein. For example, it has been a
    difficult problem to control the size, density and distribution of the graphite nodules formed in
    the malleable iron during the heat treatment. But on the other hand nodular graphite cast iron is
    produced directly from the melt and thus requires no further heat treatment.

    References:

    1. ‘Nuclei for heterogeneous formation of graphite spheroids in ductile cast iron’ - J. K.


    Solberg and M. I. Onsøien (2001)
    2. ‘A Proposed Theory of Nodularization of Graphite in Cast Irons’ - S. Yamamoto,B.
    Chang,Y. Kawano,R. Ozaki &Y. Murakami. (July 18, 2013)
    3. ‘Mechanism of nodularization of graphite in cast irons treated with magnesium.’ - S.
    Yamamoto,B. Chang,Y. Kawano,R. Ozaki &Y. Murakami. (July 18, 2013)
    4. ‘Perspectives on research on the formation of nodular graphite in cast iron.’ - Gustaf
    Östberg. (May 26, 2004)
    5. ‘Materials & Design.’ - Volume 27, Issue 10, 2006.
    6. ‘Magnesium-Treated Malleable Iron.’ - A. P. Gagnebin, ET AL. (December 18, 1951)
    7. ‘Method of testing the magnesium content of Magnesium-Treated cast Iron.’ – John V.
    Dawson, Peter White. (Jan. 24, 1989)
    8. ‘Magnesium-treated decarburizingly-annealed cast iron material.’ – Anton Alt, Guenter
    Schulte, Peter Toelke, Ludwig Wilhelm, George Fischer AG. (Sep. 9, 1987)

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