On the relaxation of the long-range internal stresses of deformed copper upon unloading

A. Borbély, W. Blum, T. Ungár

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Single and polycrystalline samples of Cu were deformed at a constant shear stress of 1.43×10-3 G (G, shear modulus). At room temperature deformation ceases owing to work hardening after formation of a cell structure; at 527 K a steady state of deformation is reached with formation of a subgrain structure which is frozen in by cooling to room temperature at constant load. The dislocation density and the internal stresses were determined by analyzing the 200 Bragg peaks measured with high resolution. Measurements under load show broadening of the peaks by deformation owing to an increase of dislocation density and a build-up of long-range internal stresses. Subsequent removal of the load causes the dislocation density to decrease by 17-30%, and the internal forward stress in the hard regions of concentrated stress to decrease by one-third. It is concluded that the factor of average stress concentration in hard regions is about 2 in the work hardened state at room temperature as well as in the steady-state deformation at 527 K.

Original languageEnglish
Pages (from-to)186-194
Number of pages9
JournalMaterials Science and Engineering A
Volume276
Issue number1-2
Publication statusPublished - Jan 15 2000

Fingerprint

unloading
Unloading
residual stress
Copper
Residual stresses
copper
Loads (forces)
room temperature
work hardening
stress concentration
Strain hardening
Temperature
shear stress
Stress concentration
Shear stress
Elastic moduli
Cells
shear
Cooling
cooling

Keywords

  • Dislocation cell structure
  • Dislocation density
  • Long-range internal stress
  • Subgrain
  • X-ray Bragg peak

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

On the relaxation of the long-range internal stresses of deformed copper upon unloading. / Borbély, A.; Blum, W.; Ungár, T.

In: Materials Science and Engineering A, Vol. 276, No. 1-2, 15.01.2000, p. 186-194.

Research output: Contribution to journalArticle

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N2 - Single and polycrystalline samples of Cu were deformed at a constant shear stress of 1.43×10-3 G (G, shear modulus). At room temperature deformation ceases owing to work hardening after formation of a cell structure; at 527 K a steady state of deformation is reached with formation of a subgrain structure which is frozen in by cooling to room temperature at constant load. The dislocation density and the internal stresses were determined by analyzing the 200 Bragg peaks measured with high resolution. Measurements under load show broadening of the peaks by deformation owing to an increase of dislocation density and a build-up of long-range internal stresses. Subsequent removal of the load causes the dislocation density to decrease by 17-30%, and the internal forward stress in the hard regions of concentrated stress to decrease by one-third. It is concluded that the factor of average stress concentration in hard regions is about 2 in the work hardened state at room temperature as well as in the steady-state deformation at 527 K.

AB - Single and polycrystalline samples of Cu were deformed at a constant shear stress of 1.43×10-3 G (G, shear modulus). At room temperature deformation ceases owing to work hardening after formation of a cell structure; at 527 K a steady state of deformation is reached with formation of a subgrain structure which is frozen in by cooling to room temperature at constant load. The dislocation density and the internal stresses were determined by analyzing the 200 Bragg peaks measured with high resolution. Measurements under load show broadening of the peaks by deformation owing to an increase of dislocation density and a build-up of long-range internal stresses. Subsequent removal of the load causes the dislocation density to decrease by 17-30%, and the internal forward stress in the hard regions of concentrated stress to decrease by one-third. It is concluded that the factor of average stress concentration in hard regions is about 2 in the work hardened state at room temperature as well as in the steady-state deformation at 527 K.

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