Change search
ReferencesLink to record
Permanent link

Direct link
A Transmission Electron Microscopy Study of Plate Martensite Formation in High-carbon Low Alloy Steels
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.ORCID iD: 0000-0002-7656-9733
2013 (English)In: Journal of Materials Science & Technology, ISSN 1005-0302, Vol. 29, no 4, 373-379 p.Article in journal (Refereed) Published
Abstract [en]

The martensitic microstructures in two high-carbon low alloy steels have been investigated by classical and automated crystallographic analysis under a transmission electron microscope. It is found that the martensitic substructure changes from consisting mostly of transformation twins for 1.20 mass% carbon (C) steel to both transformation twins and planar defects on {101}(M) for 1.67 mass% C steel. In the 1.67 mass% C steel it is further found that small martensite units have a rather homogeneous substructure, while large martensite units are more inhomogeneous. In addition, the martensite units in both steels are frequently found to be of zigzag patterns and have distinct crystallographic relationships with neighboring martensite units, e.g. kink or wedge couplings. Based on the present findings the development of martensite in high-carbon low alloy steels is discussed and a schematic of the martensite formation is presented. Moreover, whether the schematic view can be applied to plate martensite formation in general, is discussed.

Place, publisher, year, edition, pages
2013. Vol. 29, no 4, 373-379 p.
Keyword [en]
Transmission electron microscopy, High-carbon low alloy steel, Plate martensite
National Category
Metallurgy and Metallic Materials
URN: urn:nbn:se:kth:diva-101107DOI: 10.1016/j.jmst.2013.01.016ISI: 000317800500011ScopusID: 2-s2.0-84875631089OAI: diva2:546432

QC 20130524. Updated from manuscript to article in journal.

Available from: 2012-08-23 Created: 2012-08-23 Last updated: 2013-05-24Bibliographically approved
In thesis
1. Low Temperature Austenite Decomposition in Carbon Steels
Open this publication in new window or tab >>Low Temperature Austenite Decomposition in Carbon Steels
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Martensitic steels have become very important engineering materials in modern society. Crucial parts of everyday products are made of martensitic steels, from surgical needles and razor blades to car components and large-scale excavators. Martensite, which results from a rapid diffusionless phase transformation, has a complex nature that is challenging to characterize and to classify. Moreover the possibilities for modeling of this phase transformation have been limited, since its thermodynamics and kinetics are only reasonably well understood. However, the recent development of characterization capabilities and computational techniques, such as CALPHAD, and its applicability to ferrous martensite has not been fully explored yet.

In the present work, a thermodynamic method for predicting the martensite start temperature (Ms) of commercial steels is developed. It is based mainly on information on Ms from binary Fe-X systems obtained from experiments using very rapid cooling, and Ms values for lath and plate martensite are treated separately. Comparison with the experimental Ms of several sets of commercial steels indicates that the predictive ability is comparable to models based on experimental information of Ms from commercial steels.

A major part of the present work is dedicated to the effect of carbon content on the morphological transition from lath- to plate martensite in steels. A range of metallographic techniques were employed: (1) Optical microscopy to study the apparent morphology; (2) Transmission electron microscopy to study high-carbon plate martensite; (3) Electron backscattered diffraction to study the variant pairing tendency of martensite. The results indicate that a good understanding of the martensitic microstructure can be achieved by combining qualitative metallography with quantitative analysis, such as variant pairing analysis. This type of characterization methodology could easily be extended to any alloying system and may thus facilitate martensite characterization in general.

Finally, a minor part addresses inverse bainite, which may form in high-carbon alloys. Its coupling to regular bainite is discussed on the basis of symmetry in the Fe-C phase diagram.  

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. xii, 77 p.
Carbon steels, Electron backscattered diffraction, Martensite, Microscopy, Microstructure, Thermodynamic modeling
National Category
Metallurgy and Metallic Materials
urn:nbn:se:kth:diva-100993 (URN)978-91-7501-449-4 (ISBN)
Public defence
2012-09-27, F3, Lindstedsvägen 26, KTH, Stockholm, 10:00 (English)

QC 20120824

Available from: 2012-08-24 Created: 2012-08-22 Last updated: 2012-08-24Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Stormvinter, AlbinHedström, PeterBorgenstam, Annika
By organisation
Physical Metallurgy
In the same journal
Journal of Materials Science & Technology
Metallurgy and Metallic Materials

Search outside of DiVA

GoogleGoogle Scholar
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

Altmetric score

Total: 94 hits
ReferencesLink to record
Permanent link

Direct link