Bending fatigue of gear teeth of conventional and isotropic steels

C. Temmel; B. Karlsson; V. Leicht

doi:10.3139/105.110012

Article

Bending fatigue of gear teeth of conventional and isotropic steels

C. Temmel , B. Karlsson and V. Leicht

Published/Copyright: May 31, 2013

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From the journal HTM Journal of Heat Treatment and Materials Volume 64 Issue 2

Abstract

The bending fatigue strength of case hardened pulsator test gear wheels has been investigated for wheels in V2158 (20MnCrS5) and fatigue isotropic 158Q (≈ 20NiMo10) steels. The gear wheels in V2158 were forged either vertically or horizontally, the wheels in 158Q just vertically. Structural anisotropy levels were investigated in the horizontally forged V2158 gears. There was no noteworthy level of bending fatigue anisotropy to detect in the V2158 gears. However, the horizontally forged gears performed some 4% better than the vertically forged ones which may be explained by a somewhat more beneficial orientation and dispersion of sulfide inclusions in the horizontal gears. The fatigue isotropic 158Q steel is, in case-hardened components, obviously not required for isotropy reasons but highly appreciated for its outstanding fatigue performance. With identical heat treatment and surface condition, gears in 158Q outperform V2158 gears by some 23% in bending fatigue strength. This is explained by the material's resistance against internal surface oxidation and, to some extend, by its low inclusion content.

Kurzfassung

Die Biegeschwellfestigkeit von einsatzgehärteten Pulsatorzahnrädern aus V2158 (20MnCrS5) und 158Q (≈ 20NiMo10) wurde untersucht. Zahnräder aus V2158 wurden entweder vertikal oder horizontal geschmiedet, die Zahnräder aus 158Q ausschließlich vertikal. Die strukturelle Anisotropie von Zahnrädern wurde anhand der horizontal geschmiedeten V2158 Zahnräder untersucht. Es wurde keine nennenswerte Anisotropie gemessen, jedoch wiesen die horizontal geschmiedeten Zahnräder 4% höhere Biegeschwellfestigkeiten auf als die vertikal geschmiedeten. Dies kann mit einer wahrscheinlich günstigeren Orientierung und Verteilung der Sulfide in den horizontalen Zahnrädern erklärt werden. Hinsichtlich struktureller Anisotropie besteht offensichtlich kein Bedarf, den ermüdungsisotropen Stahl 158Q einzusetzen. Zahnräder in 158Q Material zeigen jedoch ausgezeichnete Ermüdungseigenschaften, die denen aus V2158-Material um zumindest 23% überlegen sind. Diese hervorragende Biegeschwellfestigkeit kann mit einer wenig ausgeprägten Neigung zur Oberflächenoxidation und teilweise dem geringeren Gehalt an Einschlüssen erklärt werden.

Keywords: Isotropic quality steel; high cycle bending fatigue; transmission gear wheels; tooth strength; manganese sulfide

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Published Online: 2013-05-31

Published in Print: 2009-04-01

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Articles in the same Issue

https://doi.org/10.3139/105.110012

Keywords for this article

Isotropic quality steel; high cycle bending fatigue; transmission gear wheels; tooth strength; manganese sulfide