THE INFLUENCE OF SURFACE PHENOMENA ON THE MECHANICAL PROPERTIES OF STRUCTURAL MATERIALS, (FATIGUE OF ALUMINUM IN VACUUM).

Abstract

Techniques were developed for evaluating the fatigue life of metals by reverse bending in con trolled gaseous environments including high vacuum, and bombardment. These techniques were applied to electropolished specimens of commercia lly pure, half hard rolled aluminum sheet. The fatigue life of aluminum in reverse bending at 125 to 140 cycles per second was found to be about seven times longer in vacuum than in wet air and about four times longer in vacuum than in dry air. The cyclic strain causes more surface roughening in vacuum than in air. A hypothesis based on adsorption equilibrium and immunization to cracking by work hardening is proposed to explain the step change in life with pressure. The effectiveness of bombardment is ascribed to prevention of crack contamination by migration of mobile surface gas films. (Author)

Document Details

Document Type
Technical Report
Publication Date
Aug 01, 1963
Accession Number
AD0413671

Entities

People

  • John L. Ham

Tags

DTIC Thesaurus Topics

  • Adsorption
  • Aluminum
  • Contamination
  • Environment
  • Fatigue Life
  • Hardening
  • High Vacuum
  • Immunization
  • Materials
  • Mechanical Properties
  • Metals
  • Migration
  • Physical Properties
  • Vacuum

Readers

  • Metallurgy
  • Plasma Physics.
  • Structural Health Monitoring of Composite Structures.