ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
Regular Article
Intergranular Fatigue Crack Initiation and Its Associated Small Fatigue Crack Propagation in Water-quenched Fe–C Fully Ferritic Steel
Motomichi KoyamaZhou-Jia XiYuichi YoshidaNobuyuki YoshimuraKohsaku UshiodaHiroshi Noguchi
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2015 Volume 55 Issue 11 Pages 2463-2468


The fatigue crack initiation and propagation behavior of a water-quenched binary Fe–C fully ferritic steel was investigated though rotating-bending fatigue testing. Intergranular and transgranular crack initiation and propagation were observed. The intergranular crack propagation did not stop, while the transgranular crack propagation was retarded by crack closure and strain aging. As a result, intergranular cracking was the dominant cause of fatigue damage in the steel. A considerable number of cracks were initiated; these propagated through coalescence, which occurred mainly at the grain boundaries. Dominancy of the intergranular fatigue crack propagation increased with increasing stress amplitude. In addition, the steel showed coaxing effect significantly. The coaxing effect suppresses crack initiation as well as crack propagation.

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© 2015 by The Iron and Steel Institute of Japan
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