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Effect of deformation on microsegregation in cast structure of bearing steel
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.ORCID iD: 0000-0001-9315-7178
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Casting of Metals.
2012 (English)In: TMS 2012 141st Annual Meeting & Exhibition - Supplemental Proceedings, Vol 2: Materials Properties, Characterization, And Modeling, 2012, Vol. 2, 309-316 p.Conference paper (Refereed)
Abstract [en]

Microsegregation changes in the cast structure of a five-ton ingot of ball bearing steel are investigated by a series of hot compression tests. Cylindrical specimens are deformed at a temperature range of 800 degrees C to 900 degrees C and strain rates of 0.5 s(-1). Samples are quenched after the compression in order to eliminate the homogenization time. Subsequently they are analysed with the aid of Electron Microprobe Analysis (EMPA) in order to investigate the effect of hot compression on microsegregation of Mo, Cr, Mn and Si. It is found that highly segregated regions are regions for formation of deformation bands. It seems that the degree of microsegregation increases by increasing the deformation. An attempt is made to estimate the diffusion coefficients of alloying elements during the deformation process. The increase of microsegregation during deformation is explained by tendency for uphill diffusion.

Place, publisher, year, edition, pages
2012. Vol. 2, 309-316 p.
, TMS Annual Meeting, 2
Keyword [en]
Cast structure, Diffusion, Microsegregation, Plastic deformation
National Category
Metallurgy and Metallic Materials
URN: urn:nbn:se:kth:diva-100062ISI: 000311607900040ScopusID: 2-s2.0-84860768504ISBN: 978-111829609-7OAI: diva2:542742
141st Annual Meeting and Exhibition, TMS 2012; Orlando, FL;11 March 2012 through 15 March 2012

QC 20120803

Available from: 2012-08-03 Created: 2012-08-03 Last updated: 2013-11-04Bibliographically approved
In thesis
1. Microstructural Evolution In As-cast Alloys during Plastic Deformation
Open this publication in new window or tab >>Microstructural Evolution In As-cast Alloys during Plastic Deformation
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The effect of deformation on microstructural changes in metals and alloys is the subject of considerable practical interest. The ultimate goal is to control, improve and optimize the microstructure and texture of the finished products produced by metal forming operations. The development in the subject field is remarkable but a more in-depth study could lead us to the better understanding of the phenomena.


In the present work microstructural evolution during the plastic deformation of as-cast pure metals and alloys is studied. An experimental method was developed to study the material behavior under the hot compression testing. This method was applied on the as-cast structure of copper, bearing steel, Incoloy 825 and β brass at different temperatures and strain rates. The temperature of the samples was measured during and after the deformation process. The microstructure of the samples was examined by optical microscopy and scanning electron microscopy (SEM). The microstructural evolution during deformation process was investigated by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD). The samples were subsequently subjected to electron microprobe analysis (EMPA) to investigate the effect of the deformation on the microsegregation of Mo, Cr, Si, and Mn.


It was observed that the temperature of the samples deformed at strain rates of 5 and 10 s-1 increases abruptly after the deformation stops. However, compression test at the lower strain rates of 1 and 0.5 s-1 revealed that a constant temperature was maintained in the early stage of deformation, followed by an increase until the maximum temperature was obtained. This temperature behavior can be explained by the microstructural evolution during the deformation process. Micrograph analysis revealed the formation of deformation bands (DBs) in highly strained regions. The DBs are highly effective sites for recrystallization. The interdendritic regions are suitable sites for the formation of DBs due to the high internal energy in these regions. EMPA indicated a tendency towards uphill diffusion of Mo in the DBs with increasing strain. The effect of strain on the dissolution of carbides in the band structure of bearing steel was investigated by measuring the volume fraction of carbides inside the band structure at different strain levels. The results indicate that carbide dissolution is influenced by strain. 


The microstructural evolution inside the DBs was studied as a function of several properties: temperature, internal energy, and microsegregation. Compression of β brass revealed that twinning is the most prominent feature in the microstructure. EBSD analysis and energy calculations demonstrated that the twinning is not due to a martensitic process but rather the order/disorder transition during the deformation process. The effect of heat treatment at Tc (650°C) prior to deformation on the microstructure of β brass was also investigated, which revealed a relationship between twin formation and the anti-phase domain boundaries

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. 44 p.
plastic deformation, compression test, recrystallization, deformation band, As-cast, microsegregation, carbide dissolution, disordered structure, order/disorder transformation, twining, steel, β brass, copper
National Category
Engineering and Technology
Research subject
SRA - E-Science (SeRC)
urn:nbn:se:kth:diva-133362 (URN)978-91-7501-926-0 (ISBN)
Public defence
2013-11-22, B2, KTH,Royal Institute of technology Brinellvägen23, Stockholm, 14:43 (English)

QC 20131104

Available from: 2013-11-04 Created: 2013-10-31 Last updated: 2013-11-04Bibliographically approved

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