Digital Repository, ICF12, Ottawa 2009

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Anisotropic High Cycle Fatigue Behavior and Related Crack Initiation mechanisms in forged steel
E. Pessard, F. Morel, A. Morel, D. Bellett

Last modified: 2013-05-03


This work deals with the anisotropic fatigue behaviour of the Bainitic Steel
Metasco®MC and aims at improving the fatigue criteria used for the design of
forged components (e.g. automobile suspension arms). This material contains
elongated manganese sulphide (MnS) inclusions oriented parallel to the rolling or
forging direction. Specimens with different orientations relative to the rolling
direction have been tested in fatigue under push-pull uniaxial loads.
The influence of “inclusion clusters” is clearly demonstrated via observation of
the failure surfaces. Experiments show that the anisotropic fatigue behaviour is
due to a change in the crack initiation mechanism. At 0°, when the inclusions are
parallel to the applied stress, micro-crack initiation is controlled by the material
matrix. At 90°, elongated manganese-sulphide inclusion clusters are at the origin
of crack initiation and the fatigue strength drops significantly.

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