Improvement of fatigue limit by overload for high-tensile strength steel containing a crack in the stress concentration zone

Abstract

Purpose

The purpose of this study was to investigate the effect of overload (bending moment with plastic deformation: Mp) on three point bending specimen at the fatigue limit of high-tensile-strength steel containing a crack in the stress concentration zone.

Design/methodology/approach

An artificial semi-circular slit was introduced and Mp was applied after which bending fatigue tests were carried out.

Findings

The relationship between the level of Mp and the fatigue limit (σ_w) was proportional; the fatigue limits of specimens containing 0.2- and 0.3-mm-deep slits are improved by the Mp process as much as twice the original values; the slit size that can be rendered harmless by the Mp process is a=0.05 mm in depth; and all non-propagating cracks appeared around the artificial slit.

Originality/value

Very few studies have been conducted on the fatigue limit of materials containing crack-like surface defects after overload in the stress concentration zone. This study elucidated the effect of Mp on the fatigue limit.

Citation

Houjou, K., Takahashi, K. and Ando, K. (2013), "Improvement of fatigue limit by overload for high-tensile strength steel containing a crack in the stress concentration zone", International Journal of Structural Integrity, Vol. 4 No. 3, pp. 368-382. https://doi.org/10.1108/IJSI-09-2012-0023