University of Illinois Urbana-Champaign

Structural changes in ingot iron caused by plastic and repeated stressing

Love, W.J.

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https://hdl.handle.net/2142/112040

Description

Title
Structural changes in ingot iron caused by plastic and repeated stressing
Author(s)
Love, W.J.
Issue Date
1952-11
Keyword(s)
  • Fatigue Testing
  • Structural Changes
  • Repeated Stressing
  • Ingot Iron
Abstract
Fatigue specimens of Armco Magnetic Iron were prestrained to various levels of tensile or compressive stress, electropolished and then subjected to repeated bending stresses. At exponentially increasing numbers of stress cycles, half of the specimens were examined by employing the light microscope, electronmicrographs and x-ray diffraction patterns of the individual grain reflections. In all cases the fatigue life of ingot iron was increased by the predeformation which induced cold work. Changing the predeformation stress from tension and compression was not found to be significant. The increase of fatigue life with respect to the input prestrain energy was more pronounced when the fatigue tests were conducted at the lower of two stress levels. The initial structural change in both static and fatigue tests was by slip that first occurred in grains whose orientation and boundary constraint allowed yielding to take place at a minimum applied stress. The changes in the structure caused by repeated stressing were localized in nature and tended to concentrate in only a portion of the available grains. The slip produced within these grains tended to to localize into bands with the minimum spacing of slip lines about 0.05 to 0.1 micron. Very small cracks (2 to 3 microns long) were found to exist as early as 0.1 per cent of the fatigue life. The round shaped surface inclusions which were observed had little effect on the general structure change which occurred during static deformation or fatigue.
Publisher
Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report Name or Number
  • TAM R 33
  • 1967-0331
ISSN
0073-5264
Type of Resource
text
Language
eng
Permalink
http://hdl.handle.net/2142/112040
Sponsor(s)/Grant Number(s)
Office of Naval Research, U. S. Navy, Contract N6-ori-71, Task Order IV; Project NR-031-005
Copyright and License Information
Copyright 1952 Board of Trustees of the University of Illinois

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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.