Dislocation-source hardening in nanostructured steel produced by severe plastic deformation

Naoya Kamikawa, Xiaoxu Huang, Niels Hansen

Research output: Chapter in Book/Report/Conference proceedingConference contribution

7 Citations (Scopus)


Annealing-induced hardening and deformation-induced softening behavior has recently been found in nanostructured aluminum (fcc) produced by severe plastic deformation. It has also been demonstrated that annealing led to a decrease in ductility while deformation led to an increase in ductility. These mechanical responses are totally opposite to those in conventional coarse-grained samples. The present study explores the effect of post-process annealing or deformation on mechanical properties of nanostructured interstitial free (IF) steel (bcc). Accumulative roll-bonding was used to produce the nanostructured IF steel. The deformation structure was characterized by a lamellar boundary structure with a mean spacing of about 200 nm, consisting of high-angle boundaries, low-angle dislocation boundaries and dislocations in the volume between the boundaries. When the deformed sample was annealed at 400°C for 0.5 h, the yield stress and ultimate tensile strength increased and the elongation to failure decreased markedly. In contrast, when the annealed treatment was followed by a light rolling deformation of 15 % thickness reduction, the strength decreased and the elongation to failure increased. These results are consistent with those observed in the aluminum samples. Structural observations by transmission electron microscopy indicated that a removal of dislocations between the boundaries leads to a lack of dislocation sources, resulting in a higher stress to activate alternative dislocation sources. It was suggested that deformation rather than annealing could be a new route to improve the ductility of nanostructured metals and that a moderate light deformation gives a good balance of strength and ductility.

Original languageEnglish
Title of host publicationTHERMEC 2009
EditorsTara Chandra, Tara Chandra, Tara Chandra, N. Wanderka, N. Wanderka, N. Wanderka, Walter Reimers, Walter Reimers, Walter Reimers, M. Ionescu, M. Ionescu, M. Ionescu
PublisherTrans Tech Publications Ltd
Number of pages6
ISBN (Print)0878492941, 9780878492947
Publication statusPublished - 2010
Externally publishedYes
Event6th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2009 - Berlin, Germany
Duration: 2009 Aug 252009 Aug 29

Publication series

NameMaterials Science Forum
ISSN (Print)0255-5476
ISSN (Electronic)1662-9752


Other6th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2009


  • Dislocation-source hardening
  • Interstitial free (IF) steel
  • Nanostructured metals
  • Severe plastic deformation
  • Strengthening mechanism

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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