TY - JOUR

T1 - Very high cycle fatigue assessment at elevated temperature of 100 µm thin structures made of high-strength steel X5CrNiCuNb16-4

AU - Himmelbauer, Florian

AU - Winter, Gerhard

AU - Seisenbacher, Benjamin

AU - Grün, Florian

AU - Kiesling, Constantin

N1 - Publisher Copyright: © 2022 The Author(s).

PY - 2022/10/12

Y1 - 2022/10/12

N2 - Many components and structures are exposed to very high number of cycles and challenging environmental conditions during operation. This study contributes to a better understanding of the very high cycle fatigue (VHCF) properties of high-strength steel X5CrNiCuNb16-4 at room temperature (RT) and 350 °C. For this purpose, conventional specimens and thin-walled structures are extensively examined with novel high-frequency fatigue testing techniques at elevated temperature. Tests with unnotched specimens at 350 °C show a 21.7% reduction in fatigue strength for 107 cycles and a different failure mechanism compared to RT. In contrast, no temperature influence is observed for mildly notched specimens and even a higher local fatigue strength is found for sharply notched specimens at 350 °C. The decrease in fatigue strength for 109 cycles is more pronounced at 350 °C (−10%) than at RT (−5%), and it is proven that notched specimens adequately represent the VHCF behaviour of structures. The transferability of specimen results to components and structures is given great attention. A new proposal for the VHCF strength assessment of structures with high stress gradients is presented, which is based on specimen results, an extended material-mechanical support factor and a VHCF reduction factor. The prediction model gives conservative fatigue strength estimates for 109 cycles with a maximum deviation of 5.8%. This demonstrates that even complex shaped structures can be successfully evaluated with suitable specimens and methods.

AB - Many components and structures are exposed to very high number of cycles and challenging environmental conditions during operation. This study contributes to a better understanding of the very high cycle fatigue (VHCF) properties of high-strength steel X5CrNiCuNb16-4 at room temperature (RT) and 350 °C. For this purpose, conventional specimens and thin-walled structures are extensively examined with novel high-frequency fatigue testing techniques at elevated temperature. Tests with unnotched specimens at 350 °C show a 21.7% reduction in fatigue strength for 107 cycles and a different failure mechanism compared to RT. In contrast, no temperature influence is observed for mildly notched specimens and even a higher local fatigue strength is found for sharply notched specimens at 350 °C. The decrease in fatigue strength for 109 cycles is more pronounced at 350 °C (−10%) than at RT (−5%), and it is proven that notched specimens adequately represent the VHCF behaviour of structures. The transferability of specimen results to components and structures is given great attention. A new proposal for the VHCF strength assessment of structures with high stress gradients is presented, which is based on specimen results, an extended material-mechanical support factor and a VHCF reduction factor. The prediction model gives conservative fatigue strength estimates for 109 cycles with a maximum deviation of 5.8%. This demonstrates that even complex shaped structures can be successfully evaluated with suitable specimens and methods.

KW - 17-4 PH

KW - Component testing

KW - Fatigue strength assessment

KW - High temperature fatigue

KW - Thin-walled structures

KW - Very high cycle fatigue

UR - http://www.scopus.com/inward/record.url?scp=85144601213&partnerID=8YFLogxK

U2 - 10.1016/j.jmrt.2022.10.022

DO - 10.1016/j.jmrt.2022.10.022

M3 - Article

VL - 21.2022

SP - 1811

EP - 1829

JO - Journal of Materials Research and Technology

JF - Journal of Materials Research and Technology

SN - 2238-7854

IS - November-December

ER -