Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • 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
On the Inoculation and Graphite Morphologies of Cast Iron
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing. (Metal Casting)ORCID iD: 0000-0003-3579-8748
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Research was conducted to understand the nucleation mechanism of graphite flakes and nodules and the effect of various elements on the growth morphology of graphite. Investigations were started on flake graphite cast iron. The effect of S on the graphite morphology and MnS was experimentally analysed. The influence of various type of oxides on the growth morphology of MnS and their relation with the graphite growth morphology was studied carefully through series of experiments, and results were related to the thermodynamic calculations, performed to predict the nucleation of oxides and sulfides at any temperature. The calculations were supported by EDX analysis on particles in the samples, showing sequential nucleation of flake graphite. The austenite volume fraction and the dendrite growth orientations were affected by the addition of Al to the melt. The effect of aluminium oxide and sulfur was studied on the austenite growth morphology with the help of colour etching technique. Thermal analyses were performed to study the effect of sulfur content on austenite volume fraction and growth morphology using DSC. The latent heat of solidification and the rate of austenite formation was studied and related to the sulfur content in the alloy.

To study the effect of O and S on the graphite morphology, pure Fe-C alloy was prepared and strong de-oxidizers and de-sulfurizer (Mg, Ca and Sr) were tested. With the help of ion etching and polishing, we were able to reveal the graphite growth morphology. The morphological changes in the graphite were explained by relating it to the composition of the melt in regard of dissolved S and O in the melt. The effect of other trace elements such as S, F, O, N, P, B and Se, was also investigated by testing them on an ultra-pure Fe-C alloy. The possibility of substituting a foreign atom in the basal plane of graphite was analysed based on the bonding energy between C and the foreign atoms. The resulting change in the structure of the basal plane was studied using Avogadro software and the resulting model were compared with the experimental results. The basal plane of nodular, flake and undercooled graphite was studied with the help of HRTEM, which showed differences in the lattice spacing between different graphite morphologies. The latent heat measurement showed that flake graphite have higher energy than the undercooled or vermicular graphite. This research made us enabled to tell about the growth along c-plane in graphite and the reason behind the transition of graphite morphology.

The effect of inoculation temperature and inoculation sequence on the nodularity was studied. EDX analysis were performed and the results were compared to the thermodynamic calculations.  It was found that, the melt composition is controlling the graphite growth morphologies. Strong de-oxidizers and de-sulfurizer are necessary to reduce O and S to a level where it does not influence the graphite growth morphology. The effect of various elements on the activity of oxygen in the melt is calculated. High Al cast iron was also studied. The major problem associated with this type of alloy was that, the Mg was not effective in producing nodular graphite. Experiments showed that de-oxidizers stronger than Mg are required to increase the nodularity. Thermodynamic calculations showed that the activity of oxygen in the melt was changing strongly by increasing the Al content in the alloy. This was increasing the required oxygen level to nucleate MgO.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. , 76 p.
National Category
Metallurgy and Metallic Materials
Research subject
Materials Science and Engineering
Identifiers
URN: urn:nbn:se:kth:diva-155545ISBN: 978-91-7595-349-6 (print)OAI: oai:DiVA.org:kth-155545DiVA: diva2:761657
Public defence
2014-11-28, B2, Brinelvagen 23, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20141107

Available from: 2014-11-07 Created: 2014-11-07 Last updated: 2014-11-07Bibliographically approved
List of papers
1. Relationship Between Inoculants and the Morphologies of MnS and Graphite in Gray Cast Iron
Open this publication in new window or tab >>Relationship Between Inoculants and the Morphologies of MnS and Graphite in Gray Cast Iron
2013 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 44, no 2, 283-298 p.Article in journal (Refereed) Published
Abstract [en]

The influence of oxides and sulfides in gray cast iron on the growth morphologies of MnS and on the nucleation of graphite was experimentally investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDX) analysis with evidences that shows the possible nucleation sites for graphite nucleation. Thermodynamic studies have been done on the influence of varying sulfur concentrations on the nucleation of MnS in the melt and during solidification. The consumption of dissolved oxygen and sulfur in the melt during the cooling process was analyzed and we explored how this influenced the nucleation process of oxides and sulfides. A sequential nucleation concept of oxides and MnS is proposed in relation to the growth morphology of MnS and graphite with respect to the mechanical properties of cast iron. The nucleation of new oxides and sulfides was analyzed using thermodynamics and compared to our experimental results. Graphite nucleation on substrates other than MnS, such as MoS2 oxides and (Mo,Cr)S, was experimentally analyzed along with the influence of the substrates on graphite nucleation and growth morphology.

Keyword
Equilibrium Partition-Coefficients, Microstructure, Nucleation
National Category
Metallurgy and Metallic Materials
Research subject
SRA - E-Science (SeRC)
Identifiers
urn:nbn:se:kth:diva-120280 (URN)10.1007/s11663-012-9768-6 (DOI)000316021100006 ()2-s2.0-84878539071 (Scopus ID)
Note

QC 20130408

Available from: 2013-04-08 Created: 2013-04-04 Last updated: 2017-12-06Bibliographically approved
2. An Investigation on the Effect of S and Al on the AusteniteGrowth Morphology in Gray Cast Iron, Using Thermal Analysisand Etching Technique
Open this publication in new window or tab >>An Investigation on the Effect of S and Al on the AusteniteGrowth Morphology in Gray Cast Iron, Using Thermal Analysisand Etching Technique
2013 (English)In: Transactions of the Indian Institute of Metals, ISSN 0019-493X, Vol. 66, no 2, 185-192 p.Article in journal (Refereed) Published
Abstract [en]

The austenite nucleation and growth morphology was investigated through experiments by inoculation with pure Al in a controlled environment using DTA furnace and H.F furnace. The austenite volume fraction and the dendrite growth orientations were affected by the addition of Al to the melt. Thermal analyses were performed to study the effect of sulfur content on austenite volume fraction and growth morphology using DSC. The possibility of austenite nucleation by MnS particles was analyzed. Different sulfur contents in the alloys were resulting in change in the latent heat of solidification and the rate of austenite formation. Austenite volume fraction was measured with four methods, colour etching, DSC thermal analysis, lever rule, and using LH calculated by Thermo-Calc data base, and a comparison was made among them.

Place, publisher, year, edition, pages
Springer London, 2013
Keyword
Austenite growth morphology, cast iron, sulfur, Aluminium, thermal analysis
National Category
Metallurgy and Metallic Materials
Research subject
SRA - E-Science (SeRC)
Identifiers
urn:nbn:se:kth:diva-129565 (URN)10.1007/s12666-013-0241-2 (DOI)000315588100013 ()2-s2.0-84876292566 (Scopus ID)
Note

QC 20131008

Available from: 2013-10-02 Created: 2013-10-02 Last updated: 2017-12-06Bibliographically approved
3. Graphite growth morphologies in cast iron
Open this publication in new window or tab >>Graphite growth morphologies in cast iron
2014 (English)In: Solidification and Gravity VI, Trans Tech Publications Inc., 2014, 458-463 p.Conference paper, Published paper (Refereed)
Abstract [en]

Graphite growth morphology was studied by using InLense detector on FEG-SEM after performing ion etching on the samples. Star like and circumferential growth mechanism of graphite was observed in the graphite nodules. Pure ternary alloy of hypo eutectic and hyper eutectic composition was treated with pure Mg, Ca and Sr, to study the effect of O and S concentration in the melt, on the transition of graphite morphology from nodular to vermicular/compacted and flake graphite. The change in the melt composition between the austenite dendrites due to microsegregation of S, O and inoculants and their possible effects on the transition of graphite morphologies as well as the nucleation of new oxides/sulfides particles is discussed with the help of thermodynamics.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2014
Series
Materials Science Forum, ISSN 0255-5476 ; 790-791
Keyword
And thermodynamics, Cast iron, Clusters, Graphite morphology, Ion etching, Micro-segregation, Transition
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-146699 (URN)10.4028/www.scientific.net/MSF.790-791.458 (DOI)2-s2.0-84901434605 (Scopus ID)978-303835093-4 (ISBN)
Conference
6th International Conference on Solidification and Gravity; Miskolc, Lillafured; Hungary; 2 September 2013 through 5 September 2013
Note

QC 20140616

Available from: 2014-06-16 Created: 2014-06-13 Last updated: 2014-11-07Bibliographically approved
4. Relationship Between the Trace Elements and Graphite Growth Morphologies in Cast Iron
Open this publication in new window or tab >>Relationship Between the Trace Elements and Graphite Growth Morphologies in Cast Iron
2014 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 45, no 13, 6187-6199 p.Article in journal (Refereed) Published
Abstract [en]

The graphite morphology transition was studied using various techniques and additives in ultra-pure binary and ternary alloys with hypo- and hypereutectic compositions. Some of the trace elements were observed to stabilize the flake growth morphology of graphite, while others did not. The distance between the graphite basal planes of spheroidal, flake, and undercooled fine graphite was measured and the lattice fringes were studied using high resolution transmission electron microscope, after preparing a thin lamella of graphite using focused ion beam. Latent heat measurement was performed using differential scanning calorimeter on the pure binary alloy with and without sulfur and oxygen additions. The substitution of various elements under study in a monolayer of graphene was analyzed by considering the binding energies of the elements with C and their bonding nature. Simulations were performed using a molecule editor program and visualizer (Avogadro software), which considers various types of interatomic forces to optimize a monolayer of graphene to a minimum energy. The effect of the type of cyclic C-ring structure and energy of the basal plane of graphite with a connection to the addition of trace elements individually in the monolayer of graphene was studied and simulated to understand the resulting bulk graphite growth morphology.

Keyword
Nucleation
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-155674 (URN)10.1007/s11661-014-2589-2 (DOI)000344334900036 ()2-s2.0-84919665589 (Scopus ID)
Note

QC 20141107

Available from: 2014-11-07 Created: 2014-11-07 Last updated: 2017-12-05Bibliographically approved
5. Graphite growth control in nodular cast iron
Open this publication in new window or tab >>Graphite growth control in nodular cast iron
2014 (English)Manuscript (preprint) (Other academic)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-155675 (URN)
Note

QS 2014

Available from: 2014-11-07 Created: 2014-11-07 Last updated: 2014-11-07Bibliographically approved
6. Graphite Growth Morphologies in High Al Cast Iron
Open this publication in new window or tab >>Graphite Growth Morphologies in High Al Cast Iron
2014 (English)Manuscript (preprint) (Other academic)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-155676 (URN)
Note

QS 2014

Available from: 2014-11-07 Created: 2014-11-07 Last updated: 2014-11-07Bibliographically approved

Open Access in DiVA

Doctoral thesis(10601 kB)3042 downloads
File information
File name FULLTEXT01.pdfFile size 10601 kBChecksum SHA-512
9480b40fb82ba32a4089899f3ad638ae53fe37b2d830c814c5943d5b65d66982a1500f33e21313bf137e0575d591847a537efc61498c2f58607cca2d6b6d4c1f
Type fulltextMimetype application/pdf

Authority records BETA

Muhmond, Haji Muhammad

Search in DiVA

By author/editor
Muhmond, Haji Muhammad
By organisation
Materials Processing
Metallurgy and Metallic Materials

Search outside of DiVA

GoogleGoogle Scholar
Total: 3042 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 768 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • 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