Fractography and Crack Initiation of Very-High-Cycle Fatigue for a High Carbon Low Alloy Steel


Article Preview

Very-High-Cycle Fatigue (VHCF) is the phenomenon of fatigue damage and failure of metallic materials or structures subjected to 108 cycles of fatigue loading and beyond. This paper attempts to investigate the VHCF behavior and mechanism of a high strength low alloy steel (main composition: C-1% and Cr-1.5%; quenched at 1108K and tempered at 453K). The fractography of fatigue failure was observed by optical microscopy and scanning electron microscopy. The observations 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 from interior. 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 to the corresponding fatigue threshold of the test material. The results indicate that the fatigue life of specimens with crack origin at the interior of specimen is longer than that with crack origin at specimen surface. The experimental results and the fatigue mechanism were further analyzed in terms of fracture mechanics and fracture physics, suggesting that the primary propagation of fatigue crack within the fish-eye local region is the main characteristics of VHCF.



Key Engineering Materials (Volumes 324-325)

Edited by:

M.H. Aliabadi, Qingfen Li, Li Li and F.-G. Buchholz




C. E. Zhou et al., "Fractography and Crack Initiation of Very-High-Cycle Fatigue for a High Carbon Low Alloy Steel ", Key Engineering Materials, Vols. 324-325, pp. 1113-1116, 2006

Online since:

November 2006




[1] Wang Q Y, Berard J Y, Dubarre A, et al. Gigacycle fatigue of ferrous alloys. Fatigue Fract. Engng. Mater. Struct., 1999, 22: 667-672.

DOI: 10.1046/j.1460-2695.1999.00185.x

[2] Chapetti M D, Tagawa T, Miyata T. Ultra-long cycle fatigue of high-strength carbon steels part II: estimation of fatigue limit for failure from internal inclusions. Materials Science and Engineering A, 2003, 356(1-2): 236-244.

DOI: 10.1016/s0921-5093(03)00136-9

[3] Sakai T, Takeda M, et al. Experimental evidence of duplex S-N characteristics in wide life region for high strength steels. In: Wu X R, Wang Z G eds., proceedings of the 7th International Fatigue Congress, Beijing, 1999. 573-578.

[4] Murakami Y, Yokoyama N N, Nagata J. Mechanism of fatigue failure in ultra long life regime. Fatigue Fract. Engng. Mater. Struct., 2002, 25: 735-746.

[5] Bathias C. There is no infinite fatigue life in metallic materials. Fatigue Fract. Engng. Mater. Struct., 1999, 22: 559-565. (a) (b) (c) Fig. 5 Relationships between inclusion area, dark area, RODA/Rinclusion and number of cycles to failure.

DOI: 10.1046/j.1460-2695.1999.00183.x

Fetching data from Crossref.
This may take some time to load.