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Publications (9 of 9) Show all publications
Vynnycky, M., Saleem, S. & Fredriksson, H. (2018). An asymptotic approach to solidification shrinkage-induced macrosegregation in the continuous casting of binary alloys. Applied Mathematical Modelling, 54, 605-626
Open this publication in new window or tab >>An asymptotic approach to solidification shrinkage-induced macrosegregation in the continuous casting of binary alloys
2018 (English)In: Applied Mathematical Modelling, ISSN 0307-904X, E-ISSN 1872-8480, Vol. 54, p. 605-626Article in journal (Refereed) Published
Abstract [en]

The modelling of macrosegregation in the continuous casting of alloys normally requires resource-intensive computational fluid dynamics (CFD). By contrast, here we develop an asymptotic framework for the case when macrosegregation is driven by solidification shrinkage; as a first step, a binary alloy is considered. Systematic asymptotic analysis of the steady-state two-dimensional mass, momentum, heat and solute conservation equations in terms of the shrinkage parameter indicates that the overall problem can be reduced to a hierarchy of decoupled problems: a leading-order problem that is non-linear, and a sequence of linear problems, with the actual macrosegregation of the solute then being determined by means of one-dimensional quadrature. A numerical method that solves this sequence is then developed and implemented, and yields realistic macrosegregation profiles at low computational cost.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE INC, 2018
Keywords
Continuous casting, Binary alloys, Macrosegregation
National Category
Computational Mathematics
Identifiers
urn:nbn:se:kth:diva-222171 (URN)10.1016/j.apm.2017.10.012 (DOI)000423005000037 ()2-s2.0-85038207280 (Scopus ID)
Note

QC 20180207

Available from: 2018-02-07 Created: 2018-02-07 Last updated: 2018-02-07Bibliographically approved
Vynnycky, M. & Saleem, S. (2017). On the explicit resolution of the mushy zone in the modelling of the continuous casting of alloys. Applied Mathematical Modelling, 50, 544-568
Open this publication in new window or tab >>On the explicit resolution of the mushy zone in the modelling of the continuous casting of alloys
2017 (English)In: Applied Mathematical Modelling, ISSN 0307-904X, E-ISSN 1872-8480, Vol. 50, p. 544-568Article in journal (Refereed) Published
Abstract [en]

In the continuous casting of alloys, it is well-known that the mushy zone is decisive for the final properties of the casting. Most numerical models' for the process use enthalpy based methods on fixed grids which determine the extent the mushy zone implicitly. Here, on the other hand, we develop a methodology for explicitly resolving the geometrical extent of the mushy zone; this involves a sharp-interface formulation to solve a dual moving boundary problem to locate the solidus and liquidus isotherms. The results compare favourably with those from enthalpy-based methods, and the advantages of our approach with respect to future multiphysics calculations are discussed. 

Place, publisher, year, edition, pages
ELSEVIER SCIENCE INC, 2017
Keywords
Continuous casting, Alloys, Boundary immobilization
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-215800 (URN)10.1016/j.apm.2017.06.007 (DOI)000411534700032 ()2-s2.0-85028018216 (Scopus ID)
Note

QC 20171018

Available from: 2017-10-18 Created: 2017-10-18 Last updated: 2017-10-18Bibliographically approved
Saleem, S., Vynnycky, M. & Fredriksson, H. (2017). The Influence of Peritectic Reaction/Transformation on Crack Susceptibility in the Continuous Casting of Steels. Metallurgical and materials transactions. B, process metallurgy and materials processing science, 48(3), 1625-1635
Open this publication in new window or tab >>The Influence of Peritectic Reaction/Transformation on Crack Susceptibility in the Continuous Casting of Steels
2017 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 48, no 3, p. 1625-1635Article in journal (Refereed) Published
Abstract [en]

The work presented here examines the surface cracks that can form during the continuous casting of near peritectic steels due to the volume changes during the peritectic reaction/transformation. The investigated samples were collected during plant trials from two different steel grades. The role and mode of the peritectic reaction/transformation are found to depend on the composition of the alloy, resulting in different types of surface cracks. The effect of the local variation in the cooling rate on the formation of the different types of cracks present in each steel grade, which can be due, for example, to the formation of oscillation marks, is demonstrated. The enhanced severity of the surface and internal oxidation, both of which depend on the alloy composition and consequent peritectic reaction, is highlighted. Experimental and theoretical studies show that different types of surface cracks can occur in peritectic steels depending upon the alloy composition and cooling rate, both of which define the fraction of the remaining liquid upon completion of the peritectic reaction/transformation.

Place, publisher, year, edition, pages
Springer, 2017
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-207874 (URN)10.1007/s11663-017-0926-8 (DOI)000400385900019 ()2-s2.0-85012230367 (Scopus ID)
Funder
Swedish Energy Agency
Note

QC 20170530

Available from: 2017-05-30 Created: 2017-05-30 Last updated: 2017-11-10Bibliographically approved
Saleem, S., Vynnycky, M. & Fredriksson, H. (2016). A Study of the Oscillation Marks’ Characteristics of Continuously Cast Incoloy Alloy 825 Blooms. Metallurgical and Materials Transactions. A, 47(8), 4068-4079
Open this publication in new window or tab >>A Study of the Oscillation Marks’ Characteristics of Continuously Cast Incoloy Alloy 825 Blooms
2016 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 47, no 8, p. 4068-4079Article in journal (Refereed) Published
Abstract [en]

A comprehensive experimental study of oscillation mark (OM) formation and its characteristics during the solidification of Incoloy alloy 825 in the continuous casting of blooms is investigated by plant trials and metallographic study. The experiments involved two heats with the same casting and mold conditions and sampling at different locations across the strand. The metallographic study combined macro/micro-examinations of OMs and segregation analysis of Cr, Mn, Mo, Ni, and Si by microprobe analysis. The results show that OMs have widely different characteristics, such as mark type, depth, segregation, and accompanying microstructure. Furthermore, the mark pitch can vary considerably even for the similar casting conditions, leading to different conditions for the marks’ formation in relation to the mold’s cyclic movement. Finally, a mechanism for the OM formation is discussed and proposed. Possible solutions for minimizing the observed defects by optimizing the mold conditions are suggested.

Place, publisher, year, edition, pages
Springer Publishing Company, 2016
Keywords
Incoloy alloy 825, continuous casting, bloom, oscillations marks, microstructure, microsegregation, cracks, statistical analysis
National Category
Other Materials Engineering
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-187818 (URN)10.1007/s11661-016-3582-8 (DOI)000379494700027 ()2-s2.0-84978160768 (Scopus ID)
Projects
Reduction of oscillation marks formation
Funder
Swedish Energy Agency
Note

QC 20160530

Available from: 2016-05-30 Created: 2016-05-30 Last updated: 2017-11-30Bibliographically approved
Saleem, S. (2016). On the surface quality of continuously cast steels and phosphor bronzes. (Doctoral dissertation). Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>On the surface quality of continuously cast steels and phosphor bronzes
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis work concerns about the importance of the cast surfaces, surface phenomenon such as the formation of the oscillation marks and exudation and related defects including cracks and segregation that happened during the continuous casting. All of the investigated materials were collected during the plant trials while an in-depth analysis on these materials was performed at the laboratory scale with certain explanations supported by the schematic and theoretical models. The work consists on different material classes such as steels and phosphor bronzes with a focus on the surface defects and their improvements. In order to facilitate the theoretical analysis which could be capable of explaining the suggested phenomenon in the thesis, a reduced model is developed which required lesser computational resources with lesser convergence problems.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. p. 80
Keywords
Continuous Casting, Steels, Ni-based alloy, Peritectic, Phosphor Bronzes, Simulation and Modeling
National Category
Metallurgy and Metallic Materials
Research subject
Materials Science and Engineering; Industrial Engineering and Management; Metallurgical process science
Identifiers
urn:nbn:se:kth:diva-187718 (URN)978-91-7729-019-3 (ISBN)
Public defence
2016-06-09, Kollegiesalen, Brinellvägen 8, SE-10044, KTH-Campus, Stockholm, 14:00 (English)
Opponent
Supervisors
Projects
Oscilation mark formation during continous casting of steel
Funder
Swedish Energy AgencyVINNOVAHelge Ax:son Johnsons stiftelse
Note

QC 20160527

Available from: 2016-05-30 Created: 2016-05-27 Last updated: 2016-05-30Bibliographically approved
Saleem, S., Vynnycky, M. & Fredriksson, H.Effect of casting parameters on the formation of oscillation marks during continuous casting.
Open this publication in new window or tab >>Effect of casting parameters on the formation of oscillation marks during continuous casting
(English)Manuscript (preprint) (Other academic)
Abstract [en]

In the present investigation, oscillations marks formed at the surfaces of two different steel grades are studied; this includes metallographic investigation. The characteristics of the marks are examined rigorously, and the analysis is performed serially. The statistical data is compared withanalytical relations and possible reasons for the deviations from the average values are discussed.From the ongoing analysis, it can be seen that the formation of the primary shell is an important parameter which can affect the depth of the depression. Moreover, the results show that theformation of the oscillation marks is a complex phenomenon and that there could be more than one explanation for their formation.

National Category
Metallurgy and Metallic Materials
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-187870 (URN)
Funder
Swedish Energy Agency
Note

QC 20160608

Available from: 2016-05-30 Created: 2016-05-30 Last updated: 2016-06-08Bibliographically approved
Vynnycky, M. & Saleem, S. On the resolution of thermal gradients in a model for the continuous casting of binary alloys. Applied Mathematics and Computation
Open this publication in new window or tab >>On the resolution of thermal gradients in a model for the continuous casting of binary alloys
(English)In: Applied Mathematics and Computation, ISSN 0096-3003Article in journal (Other academic) Submitted
Place, publisher, year, edition, pages
Elsevier
Keywords
continuous casting, alloys, boundary immobilization
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-187871 (URN)
Note

QCR 20160531

Available from: 2016-05-30 Created: 2016-05-30 Last updated: 2019-06-05Bibliographically approved
Saleem, S. The influence of peritectic reaction/transformation on crack susceptibility in the continuous casting of steels. Metallurgical and Materials Transactions B
Open this publication in new window or tab >>The influence of peritectic reaction/transformation on crack susceptibility in the continuous casting of steels
(English)In: Metallurgical and Materials Transactions B, ISSN 1073-5615Article in journal (Other academic) Submitted
Place, publisher, year, edition, pages
Springer
Keywords
Continuous casting, steel, cracks, peritectic reaction/transformation, segregation, simulation and modeling
National Category
Metallurgy and Metallic Materials
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-187867 (URN)
Projects
Reduction of oscillation mark formation during continuous casting
Funder
Swedish Energy Agency
Note

QCR 20160531

Available from: 2016-05-30 Created: 2016-05-30 Last updated: 2016-05-31Bibliographically approved
Vynnycky, M., Saleem, S. & Fredriksson, H.Towards an asymptotic framework for solidification shrinkage-induced macrosegregation in the continuous casting of binary alloys.
Open this publication in new window or tab >>Towards an asymptotic framework for solidification shrinkage-induced macrosegregation in the continuous casting of binary alloys
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The modelling of macrosegregation in the continuous casting of alloysnormally requires resource-intensive computational fluid dynamics(CFD). By contrast, here we develop an asymptotic framework for thecase when macrosegregation is driven by solidification shrinkage; as a firststep, a binary alloy is considered. Systematic asymptotic analysis of thesteady-state two-dimensional mass, momentum, heat and solute conservationequations in terms of the shrinkage parameter indicates that theoverall problem can be reduced to a hierarchy of decoupled problems: aleading-order problem that is non-linear, and a sequence of linear problems,with the actual macrosegregation of the solute then being determinedby means of one-dimensional quadrature.

National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-187872 (URN)
Note

QC 20160608

Available from: 2016-05-30 Created: 2016-05-30 Last updated: 2016-06-08Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9437-3550

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