University of Illinois Urbana-Champaign

Fatigue crack initiation as function of temperature and strain rate

Stadnick, S. J.

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https://hdl.handle.net/2142/112112

Description

Title
Fatigue crack initiation as function of temperature and strain rate
Author(s)
Stadnick, S. J.
Issue Date
1974-03
Keyword(s)
  • Fatigue
  • Temperature
  • Strain
Abstract
Thirty-four specimens of pure (0.9999+) aluminum were cyclically strained under a variety of plastic strain ranges, plastic strain rates and temperatures in an atmosphere of dry nitrogen. Stable cyclic stress strain data was recorded for a variety of plastic strain rates and temperatures. A time-temperature parameter method of analysis was found to give an adequate representation of the stable cyclic stress-strain relationships for the conditions tested. The specimen surface was observed with both light and electron microscopes to determine when and where fatigue crack initiation occurred. Electropolishing was used to discover the depth and relationship of the crack to slip bands and grain boundaries. The results showed that three forms of crack initiation were present. At low temperatures, grain boundary splitting was common. At room temperature, prominent slip band initiation was prevalent, and at high temperature vacancy coalescence at the grain boundary was the major source of crack initiation. The number of cycles to initiate a crack 0.002 deep at a given strain range was found to be independent of the nature of the crack and both test temperature and plastic strain rate.
Publisher
Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report Name or Number
  • TAM R 382
  • 1974-6004
ISSN
0073-5264
Type of Resource
text
Language
eng
Permalink
http://hdl.handle.net/2142/112112
Sponsor(s)/Grant Number(s)
Advanced Research Projects Agency, ARPA Order No. 2169, 74/03
Copyright and License Information
Copyright 1974 Board of Trustees of the University of Illinois

Owning Collections

Technical Reports - Theoretical and Applied Mechanics (TAM) PRIMARY
TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.