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Title:Structural changes in ingot iron caused by plastic and repeated stressing
Author(s):Love, W.J.
Subject(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.
Issue Date:1952-11
Publisher:Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report:TAM R 33
Genre:Technical Report
Sponsor:Office of Naval Research, U. S. Navy, Contract N6-ori-71, Task Order IV; Project NR-031-005
Rights Information:Copyright 1952 Board of Trustees of the University of Illinois
Date Available in IDEALS:2021-11-04

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  • Technical Reports - Theoretical and Applied Mechanics (TAM)
    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.

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