Hardness-strength relationships in fine and ultra-fine grained metals processed through constrained groove pressing

F. Khodabakhshi, M. Haghshenas, H. Eskandari, B. Koohbor

Research output: Contribution to journalArticlepeer-review

118 Scopus citations


Fine grained (FG) and ultra-fine grained (UFG) materials processed by severe plastic deformation exhibit beneficial hardness and tensile properties. Constrained groove pressing (CGP) were employed for fabrication of FG and UFG sheet metals and accomplished into different types of metals and alloys, such as commercial pure aluminum, AA3003 aluminum alloy, commercial pure copper, nickel, titanium and low carbon steels. Tensile and hardness characteristics in the FG and UFG sheets have been assessed with the aim of evaluating the hardness-strength relationship frequently established for coarse-grained metals and alloys (σUTS/HV=3.45). However, it was revealed that the FG and UFG materials do not obey widely used hardness-strength relationships in the conventional coarse grained structures. A new multiplicity factor less than 3, depending on the chemical composition of processed materials, is proposed in this study. This is attributed to different strain hardening response of the FG and UFG materials with slight work hardening before necking instability. In fine grained and ultra-fine grained structures failure does not occur in (or right after) the onset of necking point. That is, tensile deformation sustains significantly up to fracture point due to the role of superplasticity mechanisms.

Original languageEnglish (US)
Pages (from-to)331-339
Number of pages9
JournalMaterials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
StatePublished - Jun 1 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

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


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