Bauteilfestigkeit von wärmebehandeltem Sinterstahl

FKM booklet 342
2022
188 p.

To date, there is no concept for the computational strength verification of components made of porous
sintered steel. The aim of this project was therefore to develop a computational strength verification
for sintered steels. The calculation should be possible for the widest possible range of different
alloy compositions. In order to make the calculation as simple as possible for the user
, a further requirement was the inclusion of a few input parameters
in the calculation algorithm. The density and
hardness are included in the calculation rule as material properties. The highly stressed
volume (component geometry & load) and the stress ratio were selected as stress variables.
In order to develop a computational strength verification, an extensive literature research
was first carried out to compile a large number of Wöhler lines. An attempt was made
to extract as much metadata as possible from the sources for the respective test series, such as the alloy composition,
the density and hardness, the specimen geometry, etc.
In addition, the stress variables highly stressed
volume, highly stressed surface, stress integral, shape number and related stress gradient
were determined by FEA for each extracted Wöhler line. The variables result from the sample geometry used, the
external load and the stress ratio. The data extracted and determined in this way was compiled in a machine-readable database at
.
To date, there have been no systematic studies in the literature on the fatigue behavior of
hardened sintered steels. For this reason, hardened and case-hardened
material samples were systematically produced in this project and Wöhler curves with different boundary conditions were determined.
The data sets generated in this way were able to supplement the above-mentioned database.
With the help of the extensive database, it was possible to develop
evaluation approaches for sintered steels that are independent of the alloy composition and based on easily measured parameters
. Approaches for static and cyclic loading could be determined.
With the input parameters density and hardness, as well as the local loading parameters,
it is now possible to generate a synthetic S-N curve and a design S-N curve if
the above-mentioned parameters of the sintered steel are known. Due to the size and versatility
of the compiled database, two different approaches (LBF and IWM) could be set up
, which provide results of similar quality.
To validate the calculation approaches, component tests were carried out on two different model components
.