ISSN:
1013-9826
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Very-High-Cycle Fatigue (VHCF) is the phenomenon of fatigue damage and failure ofmetallic materials or structures subjected to 108 cycles of fatigue loading and beyond. This paperattempts to investigate the VHCF behavior and mechanism of a high strength low alloy steel (maincomposition: C-1% and Cr-1.5%; quenched at 1108K and tempered at 453K). The fractography offatigue failure was observed by optical microscopy and scanning electron microscopy. Theobservations reveal that, for the number of cycles to fatigue failure between 106 and 4×108 cycles,fatigue cracks almost initiated in the interior of specimen and originated at non-metallic inclusions.An “optical dark area” (ODA) around initiation site is observed when fatigue initiation frominterior. ODA size increases with the decrease of fatigue stress, and becomes more roundness.Fracture mechanics analysis gives the stress intensity factor of ODA, which is nearly equivalent tothe corresponding fatigue threshold of the test material. The results indicate that the fatigue life ofspecimens with crack origin at the interior of specimen is longer than that with crack origin atspecimen surface. The experimental results and the fatigue mechanism were further analyzed interms of fracture mechanics and fracture physics, suggesting that the primary propagation of fatiguecrack within the fish-eye local region is the main characteristics of VHCF
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/52/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.324-325.1113.pdf
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