Fatigue striation in a wide range of crack propagation rates up to 70 ?m/cycle in a ductile structural steel

Masuda, Chitoshi; Ohta, Akihiko; Nishijima, Satoshi; Sasaki, Etsuo

doi:10.1007/bf00550582

Cited by 24 publications

(16 citation statements)

References 6 publications

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“…There are some exceptions to the rule, e.g. in the case of AlZnMg alloys (7XXX type), for which the equality v = s is acceptable, but generally, the macroscopic crack growth rate can deviate substantially from the striation spacing 17–27 . In these cases, the key question is: how to extract a trustworthy value of the macroscopic CGR from striation spacing?…”

Section: Fractographic Reconstitution Of Fatigue Crack History Based mentioning

confidence: 99%

Fractographic reconstitution of fatigue crack history – Part I

Nedbal

Lauschmann

Kunz

2008

Fatigue Fract Eng Mat Struct

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A B S T R A C T Quantitative fractography of components which have failed under cyclic loading can offer very valuable information usually unattainable by any other means -in particular, a detailed description of fatigue crack growth (FCG) in space and in time. The reliable characterization of crack propagation provides data important in engineering applications.The main source of information on the relationship between fractographic findings and macroscopic crack growth rate (CGR) is striation spacing. This quantitative microfractographic characteristic was the basis for the methods described in the paper. An application of the fractographic reconstitution of FCG is illustrated by an example of an aircraft wing spar fatigued during a full-scale test.Keywords fatigue crack growth; quantitative fractography; striation spacing. N O M E N C L A T U R Ea = crack length D = relation between macroscopic crack growth rate and striation spacing N = number of loading cycles p s = area percentage of striation patches on fracture surface v = macroscopic crack growth rate s = striation spacing K = stress intensity factor range K eff = effective value of stress intensity factor range ϑ = angle between local & macroscopic crack growth direction I N T R O D U C T I O NFractography is a potent and useful tool for studying failure processes in a broad spectrum of applicationsfrom fundamental research on relations between material microstructure and failure micromechanisms to practical failure analysis of service events. General capability of the fractography is based on a simple axiomatic presumption: the information on a failure process history is encoded in the fracture surface, and possibly in its vicinity. The task of fractography is to decode this information, and to apply it in the fields of fracture & damage mechanics, materials science and other linked disciplines.Our interest is to discuss the information encoded in a new surface created by a fatigue crack in a cyclically loaded body. Fatigue cracks can propagate by many fracture micromechanisms. The character of the failure proCorrespondence: I. Nedbal.

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Section: Fractographic Reconstitution Of Fatigue Crack History Based mentioning

confidence: 99%

Fractographic reconstitution of fatigue crack history – Part I

Nedbal

Lauschmann

Kunz

2008

Fatigue Fract Eng Mat Struct

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“…A JEOL JEM 2010 tranmission electron microscope (TEM) at an acceleration voltage of 200 kV was employed to investigate dislocation substructure. FCGR increases with crack length even for a small crack 5,6,14 ; however, it is not the case for pure titanium for small crack. Since the specimen tested at 150 MPa showed no failure at 10 7 cycles, fractrographic analyses were performed for the three specimens tested at 175, 200 and 227 MPa as shown below.…”

Section: Fatigue Tests and Fractographic Characterizationmentioning

confidence: 87%

“…[4][5][6] In other words, there is a threshold striation spacing value, which corresponds to FCGR at small crack length. For instance, in pure iron, steels and copper, striation spacing does not correspond to FCGRs at small crack lengths.…”

Section: Introductionmentioning

confidence: 99%

Minimum fatigue striation spacing and its stress amplitude dependence in a commercially pure titanium

Ahmed

Islam

Yin

et al. 2019

Fatigue Fract Eng Mat Struct

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We report the fatigue striation spacing of commercially pure titanium with respect to stress amplitude. Rotating bending fatigue tests were performed at 150, 175, 200 and 227 MPa in which samples did not fail at 150 MPa. No fatigue striation up to a certain crack length is observed for the studied conditions. For each condition, a minimum striation spacing value is found that decreases from 0.45 to 0.36 to 0.24 μm with increasing stress from 175 to 200 to 227 MPa, respectively. The minimum striation spacing remains constant up to a certain crack length for each condition. Thereafter, it starts increasing with crack length. It is quite understandable that the constant striation spacing over a certain crack length may not represent the macroscopic fatigue crack growth rate. The fatigue crack growth mechanism during the constant striation spacing region has been discussed in detail. K E Y W O R D Scommercially pure titanium, fractrography, metal fatigue, fatigue striation

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“…The distance increase between striations probably indicates the higher rate of fatigue failure for the Cu-V composite as compared to that for the Cu-Fe composite (Fig. 6c), because the distance between striations according to some authors [22][23][24] is associated with macroscopic rate of fatigue crack propagation. In particular, it's shown in [22] that the macroscopic rate of fatigue crack propagation in steel samples was in the range of 5 Â 10 À9 -10 À7 m/cycle and the fatigue striations width was almost the same.…”

Section: Fractographic Analysismentioning

confidence: 91%

“…The striations width increased with further increase of fatigue crack rate. According to [24] the steels are characterized by the same microscopic and macroscopic rate of fatigue crack propagation in the range of 10 À7 -7 Â 10 À6 m/ cycle. Nevertheless, in the case of in-situ composites, i.e.…”

Section: Fractographic Analysismentioning

confidence: 99%