Fatigue design of sintered steel components: effect of stress concentrations and mean stresses on local strength using highest stressed volume approach

Abstract

The increasing implementation of sintered steel parts for highly loaded engine and gear box applications is accompanied by the need for reliable fatigue design, especially in the pre-development phase. In most cases necessary characteristic values for the fatigue design of PM components, especially for sharply notched areas, are not available. In the present study, the locally endurable stress amplitude for different loading modes and mean stresses is derived for a diffusion alloyed 4%Ni sintered steel (Distaloy AE) via the highly stressed volume approach. The correlation of the locally endurable stress amplitude with the highly stressed volume, defined as V_x, is estimated for x = 80% and 90%, to evaluate both approaches with regard to PM steels. The applicability of assessing local cyclic behaviour by the highly stressed volume approach is demonstrated for a typical design detail of a highly loaded PM part. Characteristic values for the fatigue design of PM components are recommended.

Acknowledgements

This work was supported by Fachverband Pulvermetallurgie FPM and financed by Stiftung Stahlanwendungsforschung under project numbers AVIF A 253 and A270. The new tools were made by GKN Sinter Metals, MIBA Sinter Austria and Schunk Sintermetalltechnik. The powder was contributed by Höganäs AB. Compaction took place at GKN Sinter Metals, Höganäs AB, MIBA Sinter Austria and Schunk Sintermetalltechnik. The specimens and components were sintered at GKN Sinter Metals, Radevormwald. All this help is gratefully acknowledged.

This paper is based on a presentation at Euro PM 2012, organised by EPMA in Basel, Switzerland on 16–19 September 2012.