Constitutive relationships for hot deformation of a carbon steel : A comparison study of compression tests and torsion tests

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal

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  • K. P. Rao
  • E. B. Hawbolt
  • H. J. McQueen
  • D. Baragar


Original languageEnglish
Pages (from-to)165-175
Journal / PublicationCanadian Metallurgical Quarterly
Issue number2
Publication statusPublished - 1993


A 0·34% carbon steel was subjected to hot working (800-1100°C) by Gleeble compression to 0·7 strain at strain rates of 0·1-8 s-1, cam plastometer compression to 0·4 strain at strain rates of 3·5-100 s-1 and torsion to fracture strains ≥ 8 at strain rates of 0·05-4 s-1. The compressive flow curves exhibited continual hardening towards saturation except at high temperatures or low strain rates where work softening finally occurred; in torsion, the curves exhibited the peak, softening and steady state characteristics of dynamic recrystallization. The sinh-Arrhenius constitutive equation was found suitable for describing the compression tests at a series of strain levels. The constants are power functions of strain with negative exponents; however, they differ for the two compression techniques as a result of anvil/specimen contact friction in the Gleeble tests and the presence of a glass lubricant in the cam plastometer. Each set of constants can be employed to predict the flow curves of the other compression test with errors of only 7% as well as the stresses at the peak strains in torsion. 

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