TY - JOUR

T1 - Refined cyclic R-curve determination through residual crack tip stress reduction by annealing

AU - Walch, Lukas

AU - Klünsner, Thomas

AU - Ressel, Gerald

AU - Marsoner, Stefan Martin

AU - Pippan, Reinhard

AU - Hackl, Alfred

AU - Leitner, Harald

AU - Hohenwarter, Anton

N1 - Publisher Copyright: © 2024 Elsevier Ltd

PY - 2024/6/27

Y1 - 2024/6/27

N2 - The accurate determination of the cyclic R-curve of the threshold of stress intensity factor range is a demanding experimental task. The main challenge concerns the introduction of a pre-crack that is open under tension loading and free of residual stresses. When pre-cracks are generated by cyclic compression-compression loading, a zone of tensile residual stresses up to the material yield strength is generated ahead of the pre-crack tip. These stresses may affect crack propagation at the beginning of fatigue crack growth and should consequently be removed especially for high-strength materials. However, subsequent stress-relief annealing is impractical for numerous metallic material classes due to undesired microstructural alterations at the temperatures required for stress relief. In the present contribution, the above-described issue is addressed for a high speed steel using single-edge notched bending specimens pre-cracked at various stages of a typical high speed steel heat treatment process. It is shown that stress-relieving via a heat treatment route is a significant improvement compared to the conventional compression pre-cracking procedures to measure material-specific cyclic R-curves.

AB - The accurate determination of the cyclic R-curve of the threshold of stress intensity factor range is a demanding experimental task. The main challenge concerns the introduction of a pre-crack that is open under tension loading and free of residual stresses. When pre-cracks are generated by cyclic compression-compression loading, a zone of tensile residual stresses up to the material yield strength is generated ahead of the pre-crack tip. These stresses may affect crack propagation at the beginning of fatigue crack growth and should consequently be removed especially for high-strength materials. However, subsequent stress-relief annealing is impractical for numerous metallic material classes due to undesired microstructural alterations at the temperatures required for stress relief. In the present contribution, the above-described issue is addressed for a high speed steel using single-edge notched bending specimens pre-cracked at various stages of a typical high speed steel heat treatment process. It is shown that stress-relieving via a heat treatment route is a significant improvement compared to the conventional compression pre-cracking procedures to measure material-specific cyclic R-curves.

KW - Cyclic R-curve

KW - Fatigue crack propagation

KW - Heat treatment

KW - Pre-cracking

KW - Stress-relief

UR - http://www.scopus.com/inward/record.url?scp=85197446941&partnerID=8YFLogxK

U2 - 10.1016/j.ijfatigue.2024.108480

DO - 10.1016/j.ijfatigue.2024.108480

M3 - Article

AN - SCOPUS:85197446941

VL - 187.2024

JO - International Journal of Fatigue

JF - International Journal of Fatigue

SN - 0142-1123

IS - October

M1 - 108480

ER -