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Mean-stress sensitivity of an ultrahigh-strength steel under uniaxial and torsional high and very high cycle fatigue loading
  • +4
  • Bernd Schönbauer,
  • Sumit Ghosh,
  • Ulrike Karr,
  • Sakari Pallaspuro,
  • Jukka Kömi,
  • Tero Frondelius,
  • Herwig Mayer
Bernd Schönbauer
Universitat fur Bodenkultur Wien

Corresponding Author:bernd.schoenbauer@boku.ac.at

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Sumit Ghosh
Oulun Yliopisto Teknillinen Tiedekunta
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Ulrike Karr
Universitat fur Bodenkultur Wien
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Sakari Pallaspuro
Oulun Yliopisto Teknillinen Tiedekunta
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Jukka Kömi
Oulun Yliopisto Teknillinen Tiedekunta
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Tero Frondelius
Oulun Yliopisto Teknillinen Tiedekunta
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Herwig Mayer
Universitat fur Bodenkultur Wien
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Abstract

The influence of load ratio on the high and very high cycle fatigue (VHCF) strength of Ck45M steel processed by thermomechanical rolling integrated direct quenching was investigated. Ultrasonic fatigue tests were performed under uniaxial and torsional loading at load ratios of R = −1, 0.05, 0.3 and 0.5 with smooth specimens and specimens containing artificially introduced defects. Up to 2×10 5 cycles, failure originated from surface aluminate inclusions and pits under both loading conditions. The prevailing fracture mechanisms in the VHCF regime were interior crack initiation under uniaxial loading and surface shear crack initiation under torsional loading. The mean-stress sensitivity and the fatigue strength were evaluated using fracture mechanics approaches. Equal fatigue limits for uniaxial and torsional loading were determined considering the size of crack initiating defects and the appropriate threshold condition for Mode-I crack growth. Furthermore, the mean-stress sensitivity is independent of loading condition and can be expressed by σ w R = σ w R = - 1 ∙ 1 - R 2 0.63 and τ w R = τ w R = - 1 ∙ 1 - R 2 0.63 .
02 May 2022Submitted to Fatigue & Fracture of Engineering Materials & Structures
02 May 2022Submission Checks Completed
02 May 2022Assigned to Editor
05 May 2022Reviewer(s) Assigned
24 May 2022Review(s) Completed, Editorial Evaluation Pending
29 May 2022Editorial Decision: Revise Minor
06 Jun 20221st Revision Received
06 Jun 2022Submission Checks Completed
06 Jun 2022Assigned to Editor
06 Jun 2022Reviewer(s) Assigned
06 Jun 2022Review(s) Completed, Editorial Evaluation Pending
07 Jun 2022Editorial Decision: Accept
Nov 2022Published in Fatigue & Fracture of Engineering Materials & Structures volume 45 issue 11 on pages 3361-3377. 10.1111/ffe.13767