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Microstructure and Property Modifications of Cold Rolled IF Steel by Local Laser Annealing

Hallberg, Håkan LU ; Adamski, Frédéric; Baïz, Sarah and Castelnau, Olivier (2017) In Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science 48(10). p.4786-4802
Abstract

Laser annealing experiments are performed on cold rolled IF steel whereby highly localized microstructure and property modification are achieved. The microstructure is seen to develop by strongly heterogeneous recrystallization to provide steep gradients, across the submillimeter scale, of grain size and crystallographic texture. Hardness mapping by microindentation is used to reveal the corresponding gradients in macroscopic properties. A 2D level set model of the microstructure development is established as a tool to further optimize the method and to investigate, for example, the development of grain size variations due to the strong and transient thermal gradient. Particular focus is given to the evolution of the beneficial γ-fiber... (More)

Laser annealing experiments are performed on cold rolled IF steel whereby highly localized microstructure and property modification are achieved. The microstructure is seen to develop by strongly heterogeneous recrystallization to provide steep gradients, across the submillimeter scale, of grain size and crystallographic texture. Hardness mapping by microindentation is used to reveal the corresponding gradients in macroscopic properties. A 2D level set model of the microstructure development is established as a tool to further optimize the method and to investigate, for example, the development of grain size variations due to the strong and transient thermal gradient. Particular focus is given to the evolution of the beneficial γ-fiber texture during laser annealing. The simulations indicate that the influence of selective growth based on anisotropic grain boundary properties only has a minor effect on texture evolution compared to heterogeneous stored energy, temperature variations, and nucleation conditions. It is also shown that although the α-fiber has an initial frequency advantage, the higher probability of γ-nucleation, in combination with a higher stored energy driving force in this fiber, promotes a stronger presence of the γ-fiber as also observed in experiments.

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Contribution to journal
publication status
published
subject
in
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
volume
48
issue
10
pages
17 pages
publisher
Springer
external identifiers
  • scopus:85024476158
  • wos:000408884300033
ISSN
1073-5623
DOI
10.1007/s11661-017-4210-y
language
English
LU publication?
yes
id
3c5987d0-0c7e-49a6-a54b-ba5bd721da34
date added to LUP
2017-07-31 10:12:48
date last changed
2018-01-16 13:22:01
@article{3c5987d0-0c7e-49a6-a54b-ba5bd721da34,
  abstract     = {<p>Laser annealing experiments are performed on cold rolled IF steel whereby highly localized microstructure and property modification are achieved. The microstructure is seen to develop by strongly heterogeneous recrystallization to provide steep gradients, across the submillimeter scale, of grain size and crystallographic texture. Hardness mapping by microindentation is used to reveal the corresponding gradients in macroscopic properties. A 2D level set model of the microstructure development is established as a tool to further optimize the method and to investigate, for example, the development of grain size variations due to the strong and transient thermal gradient. Particular focus is given to the evolution of the beneficial γ-fiber texture during laser annealing. The simulations indicate that the influence of selective growth based on anisotropic grain boundary properties only has a minor effect on texture evolution compared to heterogeneous stored energy, temperature variations, and nucleation conditions. It is also shown that although the α-fiber has an initial frequency advantage, the higher probability of γ-nucleation, in combination with a higher stored energy driving force in this fiber, promotes a stronger presence of the γ-fiber as also observed in experiments.</p>},
  author       = {Hallberg, Håkan and Adamski, Frédéric and Baïz, Sarah and Castelnau, Olivier},
  issn         = {1073-5623},
  language     = {eng},
  month        = {07},
  number       = {10},
  pages        = {4786--4802},
  publisher    = {Springer},
  series       = {Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science},
  title        = {Microstructure and Property Modifications of Cold Rolled IF Steel by Local Laser Annealing},
  url          = {http://dx.doi.org/10.1007/s11661-017-4210-y},
  volume       = {48},
  year         = {2017},
}