## Abstract

In this paper, push-pull fatigue tests of notched specimens under R = -1, 0 and 0.5 are carried out on annealed 0.1 % carbon steel and quenched-tempered 0.5 % carbon steel with H_{B} ≃ 600. The fatigue limit of a long crack, σ_{w2}, is obtained from that of a notched specimen with a sharp and deep notch whose radius is smaller than the branch point ρ_{0}. Using the present and past σ_{w2} data, the effect of the positive mean stress on the δK_{w} of the long crack is evaluated using 3.2 H_{B} (≃σ_{B}) and σ_{S}/ (3.2H_{B}), where δK_{w} is the stress intensity factor range for predicting the fatigue limit of a metal with an arbitrary crack, σ_{S} is the lower yield stress or 0.2% proof stress, σ_{B} is the ultimate tensile strength and H_{B} is the Brinell hardness. Although the σ_{w2} decreases with the mean stress, σ_{w2} is cut off by the threshold stress σ_{we} of the plastic deformation at the crack tip. For the quantitative prediction of the fatigue limit of a cracked steel with an arbitrary crack length under a positive mean stress, the σ_{w2} and σ_{we} values are approximated by simple formulae.

Original language | English |
---|---|

Pages (from-to) | 109-126 |

Number of pages | 18 |

Journal | International Journal of Fracture |

Volume | 134 |

Issue number | 2 |

DOIs | |

Publication status | Published - Jul 2005 |

## All Science Journal Classification (ASJC) codes

- Computational Mechanics
- Modelling and Simulation
- Mechanics of Materials