University of Illinois Urbana-Champaign

Analysis of time and temperature dependence of upper yield point in iron

Bennett, P.E.; Sinclair, G.M.

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https://hdl.handle.net/2142/111866

Description

Title
Analysis of time and temperature dependence of upper yield point in iron
Author(s)
  • Bennett, P.E.
  • Sinclair, G.M.
Issue Date
1959-12
Keyword(s)
  • Time
  • Temperature Dependence
  • Upper Yield Point
  • Iron
Abstract
The influence of temperature and strain rate on the upper yield point of ingot iron was studied. Torsion tests were conducted using strain rates of 12.5/sec., .25/sec., and .001/sec. over the temperature range 77°K to 525°K. The upper yield point showed a rapid increase as the temperature was lowered. An increase in the strain rate also caused an increase in the yield point. An apparent activation energy can be associated with the strain rate and temperature dependence of the yield point. This energy is influenced by stress level, and it appears from the present study that the relationship can be described by an equation of the form ∆H= ∆̅H(τ- τ/τ)^b. If this relationship is substituted for ∆H in a modification of the Boltzman relation, the following result is obtained: log⁡(γ ̇/γ ̇_1 )=M ¯∆H/〖RT〗_1 〖((¯τ- τ_1)/¯τ)〗^b [1-T_1/T 〖((¯τ- τ)/(¯τ-τ_1 ))〗^b]. This equation describes the experimental data within ±3000 psi. The results of this investigation compared with tensile test data from other investigators show that state of stress is an important factor in determining whether a material will behave in a ductile or brittle fashion.
Publisher
Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report Name or Number
  • TAM R 157
  • 1967-0453
ISSN
0073-5264
Type of Resource
text
Language
eng
Permalink
http://hdl.handle.net/2142/111866
Sponsor(s)/Grant Number(s)
Wright Air Development Center, Contract No. AF 33(616)-5153, Project No. 7024
Copyright and License Information
Copyright 1959 Board of Trustees of the University of Illinois

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Technical Reports - Theoretical and Applied Mechanics (TAM) PRIMARY
TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.