Correlation between the fracture roughness and fatigue threshold of high-temperature degraded steel

We analyze the influence of degradation of 12Kh1MF heat-resistant steel under in-service and laboratory conditions on the characteristics of surface roughness after fatigue fracture. It is shown that the behavior of the threshold stress intensity factor Delta K sub th cl characterizing the effect of...

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Bibliographic Details
Published in:Materials science (New York, N.Y.) N.Y.), 2000-05, Vol.35 (6), p.796-801
Main Authors: Student, O Z, Cichosz, P, Szymkowski, J
Format: Article
Language:English
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Summary:We analyze the influence of degradation of 12Kh1MF heat-resistant steel under in-service and laboratory conditions on the characteristics of surface roughness after fatigue fracture. It is shown that the behavior of the threshold stress intensity factor Delta K sub th cl characterizing the effect of crack closure is similar to the behavior of the amplitude characteristics of surface roughness in the direction perpendicular to the direction of crack propagation. This enables to make a conclusion that the decisive role in the process of crack closure in the degraded metal is played by longitudinal shear. It is shown that hydrogen absorbed by the degraded metal determines the characteristics of its crack resistance and affects the process of crack closure. We propose a model of crack closure that additionally takes into account the influence of longitudinal shear.
ISSN:1068-820X