THE EFFECT OF A FATIGUE CRACK ON THE NOTCH STRENGTH AND FRACTURE DEVELOPMENT IN CYLINDRICAL SPECIMENS OF HEAT-TREATED 4340 STEEL

Abstract

It is important to know the effect of a fatigue notch on the notch strength of a steel, which in the present work was a 4340 steel heat-treated to characteristic strength levels. Fatiguecracked specimens for the various heat- treated conditions were tested in static tension at temperatures from 75 to -323 F to establish notch-strength transitions. The notch strengths measured with the fatigue-cracked specimens demonstrate that the notch formed in fatigue is more severe than the sharpest machined notches. The ductile-brittle transition measured with 0.5-inch cylindrical fatigue-cracked specimens occurs at higher temperatures than that for comparable 1.5-inch cylindrical specimens with the sharpest machined notches. The fatigue-notch tension data yield fracture indices of brittle behavior which parallel but which are not equal to the NDT index measured in the droop-weight tests reported by Puzak.

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Document Details

Document Type
Technical Report
Publication Date
Jun 24, 1963
Accession Number
AD0414823

Entities

People

  • E. P. Klier

Organizations

  • United States Naval Research Laboratory

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Annealing
  • Cracks
  • Drug Abuse
  • Ductile Brittle Transition
  • Embrittlement
  • Government Procurement
  • Heat Treatment
  • Hydrogen
  • Hydrogen Embrittlement
  • Materials
  • Measurement
  • Mechanical Properties
  • Military Research
  • Stresses
  • Tempering
  • Tensile Strength
  • Transition Temperature

Readers

  • Materials Science (Mechanical Engineering).