Specimen edge effects on bending fatigue of carburized steel

  • R. E. Cohen
  • D. K. Matlock
  • G. Krauss
Testing (continued)


The effects of specimen geometry on the fatigue behavior of SAE 4320 steel carburized at 927 °C were evaluated with two sets of cantilever bend specimens, one set machined with square edges and one set machined with round edges. The specimens with square edges exhibited a 13% lower fatigue limit. In comparison to the rounded samples, the lower fatigue limit in the square-edged samples was attributed to the presence of a higher volume fraction of retained austenite in the sample corners and a lower surface residual compressive stress. As a result of the differences in residual stress, preferential crack initiation sites existed in the square-edged samples at a location approximately 200 to 900 ώm from the square edge. The implications of this study on laboratory analyses of the bending fatigue performance of carburized gear steels are discussed.


Fatigue Austenite Residual Stress Fatigue Crack Specimen Geometry 
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Copyright information

© ASM International 1992

Authors and Affiliations

  • R. E. Cohen
    • 1
  • D. K. Matlock
    • 1
  • G. Krauss
    • 1
  1. 1.Advanced Steel Processing and Products Research CenterColorado School of MinesGolden

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