A new approach to the Haigh diagram of sintered steels from unalloyed iron to heat treated conditions

ABSTRACT

Systematic investigations on the fatigue strength of heat treated sintered steels with notched specimens are barely found in the literature, especially at stress ratios other than R = −1. For that reason a larger study was initiated with the aim to provide a base for safe estimates of fatigue strengths also for heat treated components. This work deals with one possibility to design a Haigh diagram for the positive mean stress range beyond R = −1. Starting point is a new approach to determine the mean stress sensitivity M. As all equations derived are based on averages, in extreme cases individual test results can deviate by more than 20% from the calculated value. Regularly, however, deviations around ±10% are observed.

KEYWORDS:

• Sintered steels
• fatigue
• heat treated
• Haigh diagram

Acknowledgements

The powders for that study were provided by Höganäs AB and Hoeganaes Corp. The specimens were compacted by Schunk Sintermetalltechnik, Heuchelheim, MIBA Sinter Austria, Vorchdorf, GKN Sinter Metals Engineering, Radevormwald, and Sinterwerke Herne, Herne, and sintered by MIBA Sinter Austria and GKN Sinter Metals. Part of this work was financially supported by the Federal Ministry for Economics and Energy under AiF-No. 20234 N/1 via Forschungskuratorium Maschinenbau (FKM).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was partly supported by Bundesministerium für Wirtschaft und Energie [AiF-No. 20234 N/1].

Notes on contributors

P. Beiss

P. Beiss studied mechanical engineering and worked in the PM industry from 1979 till 1994 when he joined the RWTH Aachen University as a professor for materials science. He retired in 2010 and keeps himself busy with fatigue studies on sintered steels.

K. Burkamp

K. Burkamp studied mechanical engineering at RWTH Aachen University. After graduating as M. Sc. in 2016 he started working as research assistant at IWM RWTH Aachen in the field of fatigue and fracture mechanics.

C. Broeckmann

C. Broeckmann studied mechanical engineering at Ruhr Universität Bochum and worked in industry from 2000 till 2008 when he became professor at Institute for Materials Applications in Mechanical Engineering (IWM) RWTH Aachen University. His fields of research are among others: mechanical strength of metals and ceramics, powder metallurgy, additive manufacturing, FEM-simulations of mechanical behavior of materials, as well as heat treatment of steel.