METALLURGICAL ASPECTS OF FRACTURE AT HIGH STRENGTH LEVELS

Abstract

The plane-strain fracture toughness of quenched and tempered AISI 4340 steel was measured in tension at room temperature with circumferentially notched and fatigue-cracked specimens. Values of G(IC) for indicating the variation encountered were 5.6, 23, and 254 in-lbs/sq in. after tempering at 212, 400, and 800 F, respectively. Cracking characteristics were influenced by tempering temperature. Below about 700 F, little stable crack growth was found and propagation occurred in a mixed mode that appeared to consist at least partly of cleavage fracture. At higher temperatures, initial cracking was stable and developed by a ductile shear process; rapid fracturing again occurred in a mixed mode. After tempering at 1000 F and above, fracture was ductile.

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Document Details

Document Type
Technical Report
Publication Date
May 01, 1963
Accession Number
AD0406167

Entities

People

  • Merrill L. Ebner
  • Walter A. Backofen

Organizations

  • Massachusetts Institute of Technology

Tags

Communities of Interest

  • Air Platforms
  • Energy and Power Technologies
  • Weapons Technologies

DTIC Thesaurus Topics

  • Air Force
  • Chemistry
  • Ferrium
  • Geography
  • Heat Treatment
  • Iron
  • Materials
  • Measurement
  • Mechanical Properties
  • Mechanical Working
  • Mechanics
  • Military Research
  • Plastic Explosives
  • Strain Hardening
  • Strain Rate
  • Three Dimensional
  • Yield Strength

Fields of Study

  • Materials science

Readers

  • Materials Science (Mechanical Engineering).