Characteristics of macrolocalization plastic deformation under uniaxial tension steel objects and their resistance to ductile fracture

Authors

  • Yu. P. Gul Department of metal heat treatment, National Metallurgical Academy of Ukraine, Gagarin Avenue, 4, 49600, Dnipropetrovsk, Ukraine, Ukraine
  • A. V. Ivchenko Department of metal heat treatment, National Metallurgical Academy of Ukraine, Gagarin Avenue, 4, 49600, Dnipropetrovsk, Ukraine, Ukraine
  • P. V. Kondratenko Department of metal heat treatment, National Metallurgical Academy of Ukraine, Gagarin Avenue, 4, 49600, Dnipropetrovsk, Ukraine, Ukraine
  • V. S. Chmeleva Department of metal heat treatment, National Metallurgical Academy of Ukraine, Gagarin Avenue, 4, 49600, Dnipropetrovsk, Ukraine, Ukraine
  • G. I. Perchun Department of metal heat treatment, National Metallurgical Academy of Ukraine, Gagarin Avenue, 4, 49600, Dnipropetrovsk, Ukraine, Ukraine

Keywords:

macrolocalization plastic deformation, uniaxial tensile tests, strain hardening, cold deformation, aging, strain hardening coefficient, the equation of Consider-Hart, the resistance of the viscous destruction.

Abstract

 

Purpose. On the basis of the comparative analysis of theoretical prerequisites and experimental results to justify the use  of  uniform  deformation  and  strain  hardening  characteristics  on  Consider-Hart  as  parameters  of  resistance  of  steel  viscous destruction. Methodology. Analytical  study  of  modern  concepts  about  the  conditions  of  microlocalization  plastic  deformation  in combination with experimental studies on the behaviour of steel under load objects from low-carbon steel in soft and hardened by cold deformation and strain ageing of structural conditions using including large samples of experimental data and their statistical treatment. Findings. Obtained  depending  on  the  structural  state  of  the  four  main  types  of  charts  of  deformation  and  fracture characterizing in including the resistance of viscous destruction shown a beneficial effect on the level of intensity of strain hardening, and confirmed a statistically favorable impact on the value of uniform deformation in the framework of the canonical equations of Consider-Hart. Offered: as explanation for the observed quantitative deviations in the experiment from the above equations, and use them as estimates of the magnitude of the dispersion property of micro volumes. It justifies the use of the uniform deformation value indicating the deviation of this value from the values of the coefficient  of strain  hardening as a measure of resistance of viscous destruction. Originality. First proposed and justified theoretically characteristic of the viscous resistance to fracture of steel in the form of the value of uniform deformation taking into account  the deviation values determined  from experiment  the values of the coefficient of strain hardening as a measure of dispersion in a distribution of speed values of strain hardening in micro load of the object. It was shown that at a sufficiently large volume of sample and the correct determination of the values of uniform strain ер, the coefficient α in the equation ер = αn (Consider-Hart), where n is the strain hardening coefficient, close to unity. Practical  value.Proposed  to  include  in  the  list  of  properties  defined  by  acceptance  tests  cold-formed  products,  especially  susceptible  to  lowtemperature (to 100 ° C) deformation aging, a new characteristic of the viscous resistance destruction: ер indicating the deviation (n-ер). Proposed mode of aging that increase the value of ер and reduce the value of (n-ер).

Author Biographies

Yu. P. Gul, Department of metal heat treatment, National Metallurgical Academy of Ukraine, Gagarin Avenue, 4, 49600, Dnipropetrovsk, Ukraine

Cand. Sc. (Tech.), Аssociate professor

A. V. Ivchenko, Department of metal heat treatment, National Metallurgical Academy of Ukraine, Gagarin Avenue, 4, 49600, Dnipropetrovsk, Ukraine

Cand. Sc. (Tech.), Senior Research Officer

P. V. Kondratenko, Department of metal heat treatment, National Metallurgical Academy of Ukraine, Gagarin Avenue, 4, 49600, Dnipropetrovsk, Ukraine

Graduate student

V. S. Chmeleva, Department of metal heat treatment, National Metallurgical Academy of Ukraine, Gagarin Avenue, 4, 49600, Dnipropetrovsk, Ukraine

к.т.н., доц.

G. I. Perchun, Department of metal heat treatment, National Metallurgical Academy of Ukraine, Gagarin Avenue, 4, 49600, Dnipropetrovsk, Ukraine

Cand. Sc. (Tech.), Аssociate professor

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Published

2016-03-22

Issue

Section

Proceedings in memory of Starodubov