The Effects of Surface Layer on Plastic Deformation and Crack Propagation

Abstract

The rate of crack propagation was measured in three materials -- aluminum 2014-T6, titanium (6Al-4V), and 4130 steel. Cyclic loading tests were performed at room temperature with the ratio of minimum to maximum stress intensity K sub min/K sub max = 0.25. Center-cracked and Ripling specimens were used for plane stress testing while compact tension (CT) specimens were used for plane strain testing. The effect of prestress and surface layer elimination treatment was investigated. A significant reduction in the crack propagation rate was observed with this treatment. The improvement was maximum at low stress intensity values both in plane stress and plane strain conditions. The optimum improvement was observed in specimens that were prestressed just below the yield and the surface removed.

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Document Details

Document Type
Technical Report
Publication Date
Aug 01, 1971
Accession Number
AD0731825

Entities

People

  • Avinash Kumar
  • I. R. Kramer

Organizations

  • Martin Marietta

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Aluminum Alloys
  • Creep
  • Crystal Structure
  • Fracture (Mechanics)
  • Hydroxides
  • Materials
  • Materials Science
  • Mechanical Properties
  • Mechanics
  • Plastic Deformation
  • Plastic Flow
  • Resistance
  • Stress Corrosion
  • Stress Intensity Factors
  • Stress Strain Relations
  • Titanium Alloys
  • Yield Strength

Readers

  • Materials Science (Mechanical Engineering).
  • Surface Coatings Technology.