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Influence of remaining casting skin on the fatigue strength of cast iron components

: Bergner, Kim Martine; Bleicher, Christoph; Wagener, Rainer

Fulltext ()

Procedia Structural Integrity 18 (2019), pp.792-801
ISSN: 2452-3216
International Conference on Fracture and Structural Integrity <25, 2019, Catania>
Journal Article, Conference Paper, Electronic Publication
Fraunhofer LBF ()
fatigue strength; casting skin

The assessment of the fatigue strength of castings with remaining casting skin still constitutes a challenge. Until now, only the roughness of the casting skin has been considered, by a reduction factor, during the design process. This reduction factor, however, neglects the influence of discontinuities such as inhomogeneous microstructures, imperfections, pores etc. In this work, the casting skin represents the rim zone of the casting, consisting of surface roughness and a deviating microstructure.
To assess the influence of the casting skin on the fatigue strength, stress- and strain-controlled fatigue tests on EN-GJS-400-15 and EN-GJS-700-2, specimens with deviating casting skins, were conducted. The cyclic behavior of the rim zone microstructure was determined via cyclic axial strain tests under alternating loading Rε = -1 on small flat specimens extracted from the rim zone. For the integration of the results from the axial fatigue tests with the influence of the surface roughness, as well as stress gradients present in cast components, on fatigue strength, cyclic bending tests under alternating Rσ = -1, and pulsating loading Rσ = 0, were performed. The conclusions gained from this work will be transferred in a fatigue assessment concept for the remaining casting skin on cast components.