PLASTIC BEHAVIOR OF METALS AT CRYOGENIC TEMPERATURES.

Abstract

The serrated yielding exhibited by metals during tension tests at temperatures near absolute zero is the principal consideration of the paper. Stress-strain curves are presented for various metals including Armco iron, 'K' Monel, and titanium at temperatures from +200 to -269 C. The variations of yield stress and ductility are shown to depend primarily on crystal structure. At -269 C, serrated yielding occurs in many metals. This is caused by adiabatic heating, and can occur independently of the deformation mechanism. A partial differential equation is derived relating load to strain hardening, strain rate, and thermal softening. At cryogenic temperatures, it is shown that thermal softening becomes so large that maximum load is exceeded, and discontinuous yielding occurs. During yielding, heating occurs, reducing the therma-softening term, and serration ceases. (Author)

Document Details

Document Type
Technical Report
Publication Date
Dec 01, 1965
Accession Number
AD0628491

Entities

People

  • Eric B. Kula
  • Thomas S. Desisto

Organizations

  • United States Army Research Laboratory

Tags

DTIC Thesaurus Topics

  • Crystal Structure
  • Differential Equations
  • Equations
  • Hardening
  • Metals
  • Partial Differential Equations
  • Softening
  • Strain Hardening
  • Strain Rate
  • Stress Strain Relations
  • Stresses

Fields of Study

  • Physics

Readers

  • Materials Science (Mechanical Engineering).
  • Materials Science and Engineering.
  • Thermal Physics or Thermal Science.