Tooth root bending fatigue strength of small-module sinter-hardened spur gears

ABSTRACT

The present paper is aimed at investigating the effect of the sinter-hardening treatment in improving the tooth root fatigue resistance of gears obtained by Powder Metallurgy. The gears were produced using two types of low-alloyed partially diffused steel powders, Distaloy DC and Distaloy DH (Höganäs AB, Sweden), that were conventionally sintered as well as sinter-hardened. A different microstructure was obtained after the two sintering processes that led to different fatigue response. As expected, the martensitic microstructure is responsible for good fatigue performances, slightly less than those of gears made with wrought low-alloyed quenched and tempered steels.

KEYWORDS:

• Small-module gears
• sinter-hardening
• fatigue
• Wöhler curve
• crack propagation

Acknowledgements

The authors thank Alessandro De Nicolò of GKN Sinter metals for supporting this research.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Cinzia Menapace is a research assistant at the Department of Industrial Engineering of the University of Trento, in the area of metallurgy. She has been working in Powder Metallurgy for 16 years, pursuing a PhD thesis about the sintering of bronze. In the Powder Metallurgy field, she worked on: conventional press and sinter (solid phase and liquid phase sintering, dimensional control during sintering); SPS (spark plasma sintering); milling of powders to get nano-structured powders; MIM (metal injection moulding); tape casting. Currently she is a lecturer of Metallurgical Technologies at the University of Trento for the bachelor’s degree course of Industrial Engineering.

Matteo Benedetti is an associate professor of Machine Design at the University of Trento (Italy). He was a research assistant at the Technical University Hamburg-Harburg (Germany) in 2002–03. His research interests include (a) characterisation and modelling of the mechanical behaviour of materials subjected to static and cyclic loads, (b) study of the propagation conditions of fatigue cracks, even emanating from notches under complex loading conditions, in metallic materials with particular attention to titanium alloys, (c) experimental measure and numerical modelling of residual stress fields, (d) structural integrity of machine elements and structural details.

ORCID

M. Benedetti http://orcid.org/0000-0001-9158-2429