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Effect of small defect orientation on fatigue limit of carbon steels
Author(s) -
Lorenzino P.,
Okazaki S.,
Matsunaga H.,
Murakami Y.
Publication year - 2015
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/ffe.12321
Subject(s) - tilt (camera) , materials science , fatigue limit , limit (mathematics) , carbon steel , plane (geometry) , structural engineering , surface (topology) , orientation (vector space) , mechanics , composite material , geometry , mathematical analysis , mathematics , physics , engineering , corrosion
In order to clarify the effect of defect orientation on the fatigue limit of two types of steels, JIS‐S15C and JIS‐S45C, a small semi‐circular slit was introduced onto the surface of a round specimen. The slit was tilted at 0 °, 30 ° or 60 ° with respect to the plane normal to the loading axis, but all of them had the same defect size, area = 188 µm, where the area denotes the area of the domain defined by projecting the defect on a plane normal to the loading axis. In all the combinations of the materials and tilt angles, a non‐propagating crack was found at or just below the fatigue limit, that is, the fatigue limit was determined by the non‐propagation condition of a crack initiated from the defect. In both steels, the fatigue limit was found to be nearly independent of the tilt angle for the same value of projected size area , which was in good agreement with the prediction by the area parameter model. In this paper, a mechanistic explanation for the insensitivity of the fatigue limit to the tilt angle is proposed.