Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • 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
Deformation induced martensitic transformation of metastable stainless steel AISI 301
2005 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Metastable stainless steels are promising engineering materials demonstrating good corrosion resistance and mechanical properties. Their mechanical properties are however significantly affected by the deformation induced martensitic transformation. Hence, in order to use these steels to their full potential it is vital to have profound knowledge on this martensitic phase transformation. The aim of this thesis was therefore to investigate the evolution of phase fractions, texture, microstrains and microstructure to improve the current understanding of the deformation induced martensitic transformation in AISI 301. To investigate the deformation behavior of AISI 301, in-situ high-energy x- ray diffraction during tensile loading has been performed on samples suffering different cold rolling reduction. Ex-situ transmission electron microscopy, electron back-scattered diffraction and optical microscopy were also used to characterize the microstructure at different deformation levels. The results show that parts of the austenite transforms to both ά- martensite and ε-martensite during deformation of AISI 301. The transformation behavior of ά-martensite is however completely different from the transformation behavior of ε-martensite. ε-martensite forms in a parabolic behavior, while the ά-martensite transformation can be divided in three characteristic stages. The third transformation stage of ά-martensite has previously not been reported and it is characterized by a series of rapid transformations, each of which is followed by a period of yielding without any transformation. Moreover, the lattice strain evolution in the austenite at high plastic strains was found to be oscillatory, which is correlated with the stepwise transformation of ά-martensite as well as changes in x-ray peak broadening. This behavior was also coupled with the evolution of microstructure, where a distinct banded structure consisting of slip bands and Ü-martensite was observed at low plastic strains. This banded structure was however broken at high plastic strains when the ά-martensite grew larger and formed a block- shaped morphology. These findings lead to the conclusion that the three stages of ά- martensite transformation is due to different stages of nucleation and growth. The ά-martensite will first form as small nucleus, mainly at dislocation pile-ups along slip bands. The nucleuses will grow moderately in size and the structure will become saturated with nucleuses. Hence, the only way more ά-martensite can form is by growth of the existing nucleuses. This growth is very localized and seen as bursts in the transformation curve. The oscillatory behavior observed for the lattice strains during martensite formation possibly originate when semicoherent boundaries between austenite and ά-martensite become incoherent as the ά-martensite grow large.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2005. , p. 75
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757 ; 2005:79
National Category
Other Materials Engineering
Research subject
Engineering Materials
Identifiers
URN: urn:nbn:se:ltu:diva-25748Local ID: af0808c0-8ab3-11db-8975-000ea68e967bOAI: oai:DiVA.org:ltu-25748DiVA, id: diva2:998904
Note
Godkänd; 2005; 20061213 (haneit)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-06-13Bibliographically approved

Open Access in DiVA

fulltext(4330 kB)654 downloads
File information
File name FULLTEXT01.pdfFile size 4330 kBChecksum SHA-512
668ed448e0589d359660665af16849c63946adb9d158982ded8e43bbfecdaadaa8c30e82726dae2a3ef54fc49463130bbc91ffed1c2de126acbcc2fef8c29081
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Hedström, Peter
Other Materials Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 654 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

urn-nbn

Altmetric score

urn-nbn
Total: 235 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • 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