University of Illinois Urbana-Champaign

Effect of size of specimen on fatigue strength of SAE 4340 steel

Dolan, Thomas J.; Hanley, B.C.

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https://hdl.handle.net/2142/112361

Description

Title
Effect of size of specimen on fatigue strength of SAE 4340 steel
Author(s)
  • Dolan, Thomas J.
  • Hanley, B.C.
Issue Date
1948-05
Keyword(s)
  • Specimen Size
  • Fatigue Strength
  • Steel
Abstract
The purpose of this study was to investigate the effect of size of test specimen on the fatigue strength of unnotched and notched specimens of SAE 4340 steel heat-treated to an ultimate tensile strength exceeding 160,000 psi. Rotating cantilever-beam fatigue tests were made of five sets of unnotched and of notched specimens whose diameters in the critical test section were 0.125”, 0.25”, 0.50”, 1.00” and 1.75”, respectively. The notched specimens were geometrically similar; each had a semi-circular notch whose radius was 0.08 times the diameter of the specimen at the root of the notch. The same value for the endurance limit was obtained from the test data for the two largest sizes of unnotched specimens, the value being about 74,000 psi. The endurance limits increased with decreasing diameter of the specimen, to a value of 82,500 psi. for the 1/8” unnotched specimens. For the notched specimens, the endurance limits ranged from 42,000 psi. for 1-3/4” specimens to 51,700 psi. for the 1/8” specimens. However, it is believed that the endurance limit for the notched 1-3/4” diameter specimens should have been about 45,000 psi., if the material in the critical test region had been metallurgically the same as that in the other specimens; further experiments are being made to check this tentative conclusion. The ¼” and ½” notched specimens both had an endurance limit of 48,000 psi, and the 1” specimens an endurance limit of 46,000 psi.
Publisher
Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report Name or Number
  • TAM R 6
  • 1967-0305
ISSN
0073-5264
Type of Resource
text
Language
eng
Permalink
http://hdl.handle.net/2142/112361
Sponsor(s)/Grant Number(s)
Air Materiel Command, Army Air Forces, Contract No. W33-ac-14712 (16159); Office of Naval Research, U.S. Navy Contract N6-ori-71, Task Order IV
Copyright and License Information
Copyright 1948 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.