University of Illinois Urbana-Champaign

Some aspects of effect of metallurgical structure on fatigue strength and notch sensitivity of steel

Dolan, Thomas J.; Yen, C.S.

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https://hdl.handle.net/2142/112250

Description

Title
Some aspects of effect of metallurgical structure on fatigue strength and notch sensitivity of steel
Author(s)
  • Dolan, Thomas J.
  • Yen, C.S.
Issue Date
1948-03
Keyword(s)
  • Metallurgy
  • Fatigue Strength
  • Notch-sensitivity
  • Steel
Abstract
It was the purpose of the study reported herein to determine the extent to which a change in metallurgical structure (produced by a different heat treatment) affected the fatigue strength and notch-sensitivity for several steels. Since steels having a tempered martensitic structure exhibit Charpy impact properties superior to those obtained for pearlitic steels, it was desired to ascertain whether the constituents that improve localized toughness in an impact test, would also prove beneficial in a fatigue test. Experimental data are presented from static tensile, flexural fatigue, and Charpy bending impact tests, on two alloy steels and one carbon steel, quenched and tempered to approximately the same hardness level. Duplicate tests were made for each steel in a drastically quenched and tempered condition, and for a slowly quenched and tempered condition. In general, the steels having a structure of tempered martensite exhibited higher yield ratios, slightly higher endurance limits, and less notch-sensitivity than the same steels slowly quenched and tempered. The fatigue strength of tempered martensitic specimens with a 60° V-notch, ranged from 11 to 44 percent higher than for the same metals heat treated to a structure of pearlite plus ferrite (but having the same hardness and tensile strength). Essential differences are pointed out in the structural actions occurring in a fatigue test as compared with those in the single-blow notch-bar impact test. As a result of the tests it was concluded that no direct functional relationship was apparent between the notch-sensitivity in a fatigue test and that in a Charpy test.
Publisher
Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report Name or Number
  • TAM R 5
  • 1967-0304
ISSN
0073-5264
Type of Resource
text
Language
eng
Permalink
http://hdl.handle.net/2142/112250
Sponsor(s)/Grant Number(s)
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.