Experimental Mechanics

, Volume 59, Issue 8, pp 1145–1157 | Cite as

Mesoscopic Strain Fields Measurement During the Allotropic αγ Transformation in High Purity Iron

  • N. Bruzy
  • M. CoretEmail author
  • B. Huneau
  • G. Kermouche
  • M. Mondon
  • E. Bertrand
  • L. Stainier


The allotropic phase change from ferrite to austenite represents a moment of massive interplay between the microstructural and mechanical states of iron. The difference of compacity between the two phases induces a microplastic accommodation in the material at grain scale. However, mechanical heterogeneities resulting from the transformation process remain challenging to characterise due to the high temperature conditions it is associated with. We developed experimental equipment for in situ observation of αγ and γα transformations. Images of the surface of an iron sample taken by an optical camera were used as input for a Digital Image Correlation (DIC) routine. Special care was taken to maximize image resolution to capture sub-grain phenomena. Observations show that, at the mesoscopic scale, shear strain fields exhibit strong localisations that are evidence of transformations that are occurring.


Digital image correlation High temperature Allotropic transformation Pure iron 



This work is part of the SMICE project, which was funded by BPI France under grant P113013-2660682. The authors are extremely grateful to Julien Réthoré for providing access to the UFreckles software and for giving precious advice on how to use it.


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Copyright information

© Society for Experimental Mechanics 2019

Authors and Affiliations

  1. 1.Institut de Recherche en Génie Civil et Mécanique (GeM) UMR6183Ecole Centrale de Nantes, Université de Nantes, CNRSNantesFrance
  2. 2.Laboratoire Georges Friedel (LGF) UMR5307Mines de Saint-Etienne, Université de Lyon, CNRS, Centre SMSSaint-EtienneFrance
  3. 3.Institut des Matériaux Jean Rouxel (IMN) UMR6502Université de Nantes, CNRSNantesFrance

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