Overload effects on a ferritic-baintic steel and a cast aluminium alloy: two very different behaviours
Nicolas Saintier,Thierry Palin-Luc,H. Bidonard,C. el Dsoki,Heinz Kaufmann,C. Dumas,F. J. Völlmecke,Cetin Morris Sonsino +7 more
TLDR
Load controlled fatigue tests were performed up to 107 cycles on flat notched specimens (Kt = 2.5) under constant amplitude and variable amplitude loadings with and without periodical overloads.Abstract:
Load controlled fatigue tests were performed up to 107 cycles on flat notched specimens (Kt = 2.5) under constant amplitude and variable amplitude loadings with and without periodical overloads. Two materials are studied: a ferritic-bainitic steel and a cast aluminium alloy. These materials have a very different cyclic behaviour: the steel exhibits cyclic strain softening whereas the Al alloy shows cyclic strain hardening. The fatigue tests show that, for the steel, periodical overload applications reduce significantly the fatigue life for fully reversed load ratio (Rσ = –1), while they have no influence under pulsating loading (Rσ = 0). For the Al alloy overloads have an effect (fatigue life decreasing) only for variable amplitude loadings. The detrimental effect of overloads on the steel is due to ratcheting at the notch root which evolution is overload's dependent.
An gekerbten Flachproben (Kt = 2,5) wurden Schwingfestigkeitsversuche bis 107 Schwingspiele unter konstanten und variablen Amplituden mit und ohne periodische Uberlasten durchgefuhrt. Die beiden untersuchten Werkstoffe waren ein zyklisch entfestigender ferritisch-bainitischer Stahl und eine zyklische verfestigende Aluminiumgusslegierung. Die Schwingfestigkeitsversuche zeigten fur den Stahl, dass die periodischen Uberlasten die Lebensdauer des Stahls unter Wechselbelastung (Rσ = –1) signifikant verkurzten, wahrend unter Schwellbelastung (Rσ = 0) kein Einfluss zu beobachten war. Fur die Aluminiumgusslegierung war nur unter variablen Amplituden ein lebensdauerverkurzender Effekt zu beobachten. Der nachteilige Einfluss der Uberlasten auf die Lebensdauer des Stahls ist auf uberlastenabhangiges, zyklische Kriechen im Kerbgrund zuruckzufuhren.read more
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Journal ArticleDOI
Effects of LCF Loadings on the HCF Life of Notched Specimens in Ferritic-Bainitic Steel
Hadrien Bidouard,Thierry Palin-Luc,Nicolas Saintier,C. Dumas,Chalid el Dsoki,Heinz Kaufmann,Cetin Morris Sonsino +6 more
TL;DR: In this paper, fatigue tests were performed on ferritic bainitic steel notched specimens (Kt = 2.5) under load controlled constant amplitude loading and showed that periodical overloads have a detrimental effect on the fatigue crack initiation strength.
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