Journal ArticleDOI
S–N curve characteristics and subsurface crack initiation behaviour in ultra‐long life fatigue of a high carbon‐chromium bearing steel
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TLDR
In this paper, the S-N curve obtained from cantilever-type rotary bending fatigue tests using hourglass-shaped specimens of high carbon-chromium bearing steel was characterized as a duplex S −N curve composed of two different S − N curves corresponding to the respective fracture modes.Abstract:
The S–N curve obtained from cantilever-type rotary bending fatigue tests using hour-glass-shaped specimens of high carbon-chromium bearing steel clearly distinguished the fracture modes into two groups each having a different crack origin. One was governed by crystal slip on the specimen surface, which occurred in the region of short fatigue life and a high stress amplitude level. The other was governed by a non-metallic inclusion at a subsurface level which occurred in the region of long fatigue life and low stress amplitude. The inclusion developed a fish-eye fracture mode that was distributed over a wide range of stress amplitude not only below the fatigue limit defined as the threshold for fracture due to the surface slip mode but also above the fatigue limit. This remarkable shape of the S–N curve was different from the step-wise one reported in previous literature and is characterized as a duplex S–N curve composed of two different S–N curves corresponding to the respective fracture modes. From detailed observations of the fracture surface and the fatigue crack origin, the mechanisms for the internal fracture mode and the characteristics of the S–N curve are discussed.read more
Citations
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Journal ArticleDOI
Subsurface crack initiation and propagation mechanism in high-strength steel in a very high cycle fatigue regime
TL;DR: In this article, the mechanism for the formation of the GBF area was proposed as the "dispersive decohesion of spherical carbide" model, in which during the fatigue process multiple microcracks are initiated dispersively by de-cohesion of the carbide from the matrix around a non-metallic inclusion.
Journal ArticleDOI
The formation mechanism of characteristic region at crack initiation for very-high-cycle fatigue of high-strength steels
TL;DR: In this article, the formation mechanism of FGA is proposed: Numerous Cyclic Pressing (NCP) between originated crack surfaces, which causes grain refinement at the originated crack wake and therefore the formation of fine-granular area (FGA).
Journal ArticleDOI
General relation between tensile strength and fatigue strength of metallic materials
TL;DR: In this paper, a new universal fatigue strength formula sigma(w)=sigma(b)(C-P) was established for the first time by combining the variation tendency of fatigue crack initiation sites and the competition of defects, the fatigue damage mechanisms associated with different tensile strengths and cracking sites are explained well.
Journal ArticleDOI
Propensities of crack interior initiation and early growth for very-high-cycle fatigue of high strength steels
TL;DR: In this article, a high carbon chromium steel with fine-granular-area (FGA) was used for fatigue testing and it was shown that the formation of FGA is responsible for a majority part of total fatigue life.
Journal ArticleDOI
Fatigue propagation threshold of short cracks under constant amplitude loading
TL;DR: In this paper, a threshold for fatigue crack propagation as a function of crack length is defined from a depth given by the position d of the strongest microstructural barrier to crack propagation, which defines the plain fatigue limit.
References
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Journal ArticleDOI
Effects of defects, inclusions and inhomogeneities on fatigue strength
Yukitaka Murakami,Masahiro Endo +1 more
TL;DR: In this article, the effects of defects, inclusions and inhomogeneities on the fatigue strength of metals are reviewed, from the Isibasi model and the Frost model to recent models based on fracture mechanics.
Journal ArticleDOI
Factors influencing the mechanism of superlong fatigue failure in steels
Y Murakam,T Nomoto,T Ueda +2 more
TL;DR: In this article, a particular fatigue fracture morphology in the vicinity of the fracture origin (non-metallic inclusions) of a heat-treated alloy steel, SCM435, was tested to N ≥ 10 8.
Journal ArticleDOI
Stepwise S-N curve and fish-eye failure in gigacycle fatigue
Nishijima,Kanazawa +1 more
TL;DR: In this paper, a stepwise shape in the S-N curve is represented by a fish-eye facet on the fracture surface of a material, showing that materials with a hardened surface fail from the surface only at high stresses, and at low stresses from the inside.
Book
Small Fatigue Cracks
Robert O. Ritchie,J. Lankford +1 more
TL;DR: The literature as mentioned in this paper contains over 30 papers on small crack initiation and growth under far-field cyclic compressive compression, including: Overview of the Small Crack Problem, Fatigue Crack Initiation along Slip Bands, Small Crack Environment Interactions: The Hydrogen Embrittlement Perspective, High Resolution Techniques for the Study of Small Cracks; and Crack Inititiation and Growth Under Far-Field Cyclic Compression: Theory, Experiments and Applications.
Journal ArticleDOI
Gigacycle fatigue of ferrous alloys
TL;DR: In this paper, the authors determined the very long fatigue life of ferrous alloys up to 1 x 10 10 cycles at an ultrasonic frequency of 20 kHz, and a good agreement was found with the results from conventional tests at a frequency of 25 Hz by Renault between 10 5 and 10 7 cycles for a spheroidal graphite cast iron.
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Factors influencing the mechanism of superlong fatigue failure in steels
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