Correct Interpretation of Creep Rates: A Case Study of Cu

Wolfgang Blum, J. Dvořák, P. Král, P. Eisenlohr, V. Sklenička

Research output: Research - peer-reviewArticle

  • 3 Citations

Abstract

Traditionally the deformation resistance in creep is characterized by the minimum creep rate ε˙min and its sensitivity to stress (stress exponent n) and temperature (activation energy Q). Various values of constant n have been reported in the literature and interpreted in terms of specific mechanisms. The present case study of coarse-grained Cu at 573 K yields a stress exponent n = 9 for ε˙min in tension and a relatively low activation energy. The evolution of the deformation resistance with strain at constant tensile creep load and comparison with creep in compression without fracture indicates that the tensile ε˙min result from transition from uniform deformation to strain localization during fracture. This is confirmed by the results of creep in compression where fracture is suppressed. Both the tensile ε˙min and the compressive creep rate at strains around 0.3 can be described using existing equations for quasi-stationary deformation containing the subgrain boundary misorientation θ as structure parameter. While in the latter case constant θ leads to monotonic increase of n with stress, the tensile nine-power-law results from variable θ, and has no simple meaning. The result of this case study means that uncritical interpretation of minimum tensile creep rates as stationary ones bears a high risk of systematic errors in the determination of creep parameters and identification of creep mechanisms.

LanguageEnglish (US)
Pages1065-1068
Number of pages4
JournalJournal of Materials Science and Technology
Volume31
Issue number11
DOIs
StatePublished - Nov 1 2015
Externally publishedYes

Profile

Creep
Activation energy
Systematic errors
Loads (forces)
Temperature

Keywords

  • Activation energy
  • Creep
  • Cu
  • Minimum creep rate
  • Stress exponent

ASJC Scopus subject areas

  • Ceramics and Composites
  • Mechanics of Materials
  • Mechanical Engineering
  • Polymers and Plastics
  • Metals and Alloys
  • Materials Chemistry

Cite this

Correct Interpretation of Creep Rates : A Case Study of Cu. / Blum, Wolfgang; Dvořák, J.; Král, P.; Eisenlohr, P.; Sklenička, V.

In: Journal of Materials Science and Technology, Vol. 31, No. 11, 01.11.2015, p. 1065-1068.

Research output: Research - peer-reviewArticle

Blum, W, Dvořák, J, Král, P, Eisenlohr, P & Sklenička, V 2015, 'Correct Interpretation of Creep Rates: A Case Study of Cu' Journal of Materials Science and Technology, vol 31, no. 11, pp. 1065-1068. DOI: 10.1016/j.jmst.2015.09.012
Blum W, Dvořák J, Král P, Eisenlohr P, Sklenička V. Correct Interpretation of Creep Rates: A Case Study of Cu. Journal of Materials Science and Technology. 2015 Nov 1;31(11):1065-1068. Available from, DOI: 10.1016/j.jmst.2015.09.012
Blum, Wolfgang ; Dvořák, J. ; Král, P. ; Eisenlohr, P. ; Sklenička, V./ Correct Interpretation of Creep Rates : A Case Study of Cu. In: Journal of Materials Science and Technology. 2015 ; Vol. 31, No. 11. pp. 1065-1068
@article{9b68263683f14621b7e9c911cf00fe10,
title = "Correct Interpretation of Creep Rates: A Case Study of Cu",
abstract = "Traditionally the deformation resistance in creep is characterized by the minimum creep rate ε˙min and its sensitivity to stress (stress exponent n) and temperature (activation energy Q). Various values of constant n have been reported in the literature and interpreted in terms of specific mechanisms. The present case study of coarse-grained Cu at 573 K yields a stress exponent n = 9 for ε˙min in tension and a relatively low activation energy. The evolution of the deformation resistance with strain at constant tensile creep load and comparison with creep in compression without fracture indicates that the tensile ε˙min result from transition from uniform deformation to strain localization during fracture. This is confirmed by the results of creep in compression where fracture is suppressed. Both the tensile ε˙min and the compressive creep rate at strains around 0.3 can be described using existing equations for quasi-stationary deformation containing the subgrain boundary misorientation θ as structure parameter. While in the latter case constant θ leads to monotonic increase of n with stress, the tensile nine-power-law results from variable θ, and has no simple meaning. The result of this case study means that uncritical interpretation of minimum tensile creep rates as stationary ones bears a high risk of systematic errors in the determination of creep parameters and identification of creep mechanisms.",
keywords = "Activation energy, Creep, Cu, Minimum creep rate, Stress exponent",
author = "Wolfgang Blum and J. Dvořák and P. Král and P. Eisenlohr and V. Sklenička",
year = "2015",
month = "11",
doi = "10.1016/j.jmst.2015.09.012",
volume = "31",
pages = "1065--1068",
journal = "Journal of Materials Science and Technology",
issn = "1005-0302",
publisher = "Chinese Society of Metals",
number = "11",

}

TY - JOUR

T1 - Correct Interpretation of Creep Rates

T2 - Journal of Materials Science and Technology

AU - Blum,Wolfgang

AU - Dvořák,J.

AU - Král,P.

AU - Eisenlohr,P.

AU - Sklenička,V.

PY - 2015/11/1

Y1 - 2015/11/1

N2 - Traditionally the deformation resistance in creep is characterized by the minimum creep rate ε˙min and its sensitivity to stress (stress exponent n) and temperature (activation energy Q). Various values of constant n have been reported in the literature and interpreted in terms of specific mechanisms. The present case study of coarse-grained Cu at 573 K yields a stress exponent n = 9 for ε˙min in tension and a relatively low activation energy. The evolution of the deformation resistance with strain at constant tensile creep load and comparison with creep in compression without fracture indicates that the tensile ε˙min result from transition from uniform deformation to strain localization during fracture. This is confirmed by the results of creep in compression where fracture is suppressed. Both the tensile ε˙min and the compressive creep rate at strains around 0.3 can be described using existing equations for quasi-stationary deformation containing the subgrain boundary misorientation θ as structure parameter. While in the latter case constant θ leads to monotonic increase of n with stress, the tensile nine-power-law results from variable θ, and has no simple meaning. The result of this case study means that uncritical interpretation of minimum tensile creep rates as stationary ones bears a high risk of systematic errors in the determination of creep parameters and identification of creep mechanisms.

AB - Traditionally the deformation resistance in creep is characterized by the minimum creep rate ε˙min and its sensitivity to stress (stress exponent n) and temperature (activation energy Q). Various values of constant n have been reported in the literature and interpreted in terms of specific mechanisms. The present case study of coarse-grained Cu at 573 K yields a stress exponent n = 9 for ε˙min in tension and a relatively low activation energy. The evolution of the deformation resistance with strain at constant tensile creep load and comparison with creep in compression without fracture indicates that the tensile ε˙min result from transition from uniform deformation to strain localization during fracture. This is confirmed by the results of creep in compression where fracture is suppressed. Both the tensile ε˙min and the compressive creep rate at strains around 0.3 can be described using existing equations for quasi-stationary deformation containing the subgrain boundary misorientation θ as structure parameter. While in the latter case constant θ leads to monotonic increase of n with stress, the tensile nine-power-law results from variable θ, and has no simple meaning. The result of this case study means that uncritical interpretation of minimum tensile creep rates as stationary ones bears a high risk of systematic errors in the determination of creep parameters and identification of creep mechanisms.

KW - Activation energy

KW - Creep

KW - Cu

KW - Minimum creep rate

KW - Stress exponent

UR - http://www.scopus.com/inward/record.url?scp=84947424971&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84947424971&partnerID=8YFLogxK

U2 - 10.1016/j.jmst.2015.09.012

DO - 10.1016/j.jmst.2015.09.012

M3 - Article

VL - 31

SP - 1065

EP - 1068

JO - Journal of Materials Science and Technology

JF - Journal of Materials Science and Technology

SN - 1005-0302

IS - 11

ER -