VHCF properties and assessment of specimens and thin-walled component-like structures made of high-strength steel X5CrNiCuNb16-4

Determining the component strength from the material strength is an essential but difficult task in dimensioning. Therefore, extensive HCF and VHCF tests are carried out with specimens and thin-walled component-like structures made of X5CrNiCuNb16-4. Despite complex geometry and high-strength material, a local assessment concept of a design code is well applicable. Moreover, specimens and structures show similar VHCF properties, confirming the transferability. Large scatter in lifetime is mainly due to inclusions. Considering the stress intensity factor significantly reduces the scatter and thus enables a more reliable assessment. Furthermore, the root area parameter model provides a conservative fatigue strength for 10(7) cycles.

Automated summary

In this study, extensive HCF and VHCF tests were conducted on specimens and thin-walled component-like structures made of X5CrNiCuNb16-4. The local assessment concept of a design code proved to be applicable, despite the complex geometry and high-strength material. The transferability of VHCF properties between specimens and structures was confirmed. The large scatter in lifetime was mainly attributed to inclusions, but considering the stress intensity factor significantly reduced the scatter and enabled a more reliable assessment. Furthermore, the root area parameter model provided a conservative fatigue strength for 10(7) cycles.