Modelling the crack propagation rate for corrosion fatigue at high frequency of applied stress

Subsea structures such as pipelines are vulnerable to environment-assisted crackings (EACs). As a type of EAC, corrosion fatigue (CF) is almost inevitable. For such a process, stress corrosion (SC) and hydrogen-assisted cracking (HAC) are the two mainly driving mechanisms. And it was further pointed out that slip dissolution (SD) and hydrogen embrittlement (HE) should be responsible for SC and HAC respectively. Based on such a fact, a two-component physical model for estimating the CF crack propagation rate was proposed. The proposed model was built in a frame of fracture mechanics integrated with a dissolution model for C-Mn steel and a newly established model by the authors accounting for the influence from HE upon crack propagation. The overall CF crack propagation rate is the aggregate of the two rates predicted by the two sub-individual models, and then the crack propagation time is calculated accordingly. The model has been proven to be capable of capturing the features of HE influenced fatigue cracking behaviour as well as taking mechanical factors such as the loading frequency and stress ratio into account by comparison with the experimental data of X42 and X65 pipeline steels.

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Evaluation of Corrosion Fatigue Crack Propagation Characteristics of TMCP Steel in Synthetic Seawater under Cathodic Protection

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.26-28.1145 ◽

2007 ◽

Vol 26-28 ◽

pp. 1145-1148 ◽

Cited By ~ 1

Author(s):

Won Beom Kim ◽

Jeom Kee Paik

Keyword(s):

Fatigue Crack ◽

Crack Propagation ◽

Fatigue Crack Propagation ◽

Corrosion Fatigue ◽

Cathodic Protection ◽

Crack Propagation Rate ◽

Propagation Rate ◽

Fatigue Crack Propagation Rate ◽

Synthetic Seawater ◽

Corrosion Fatigue Crack

In this research, corrosion fatigue tests using tensile strength of 490MPa TMCP steel were performed in synthetic seawater condition to investigate the corrosion fatigue crack propagation characteristics. The influence of cathodic protection at -800mV vs. SCE on the corrosion fatigue crack propagation behavior was investigated. Relationships between da/dN versus ΔK for the material were obtained by two types of test specimens. In the present study, F(α,β) versus α(= 2a/W) relationship for the CCT specimen was calculated by J integral approach, while that for the CT specimen was determined from ASTM E647. It is found that the fatigue crack propagation rate of TMCP steel in synthetic seawater condition is faster than that in air condition at least twice. Also, it is observed that the fatigue crack propagation rate of steel with cathodic protection is in between those of seawater condition without cathodic protection and air condition.

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Corrosion–fatigue crack propagation of aluminum alloys for high-speed trains

International Journal of Modern Physics B ◽

10.1142/s021797921744009x ◽

2017 ◽

Vol 31 (16-19) ◽

pp. 1744009 ◽

Cited By ~ 4

Author(s):

Lin Shen ◽

Hui Chen ◽

Xiaoli Che ◽

Lidong Xu

Keyword(s):

Fatigue Crack ◽

Aluminum Alloys ◽

Crack Propagation ◽

Fatigue Crack Propagation ◽

Corrosion Fatigue ◽

High Speed ◽

Crack Propagation Rate ◽

Propagation Rate ◽

Fatigue Crack Propagation Rate ◽

Corrosion Fatigue Crack

A modified single-edge notch tension (SENT) specimen exposed to saline environment was utilized to investigate the corrosion–fatigue crack growth behaviors of 5083, 6005 and 7N01 aluminum alloys. The fatigue crack propagation life, corrosion–fatigue crack rate ([Formula: see text]) were tested. The microstructures and fracture surfaces of specimens were examined by optical microscopy and scanning electron microscopy (SEM). The results showed that fatigue crack propagation rate of 7N01 in 3.5% NaCl was significantly higher than 6005 and 5083 alloys. The mechanisms of anodic dissolution and hydrogen embrittlement are used to explain the results.

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Mode I Crack Propagation Experimental Analysis of Adhesive Bonded Joints Comprising Glass Fibre Composite Material under Impact and Constant Amplitude Fatigue Loading

Materials ◽

10.3390/ma14164380 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4380

Author(s):

Alirio Andres Bautista Villamil ◽

Juan Pablo Casas Rodriguez ◽

Alicia Porras Holguin ◽

Maribel Silva Barrera

Keyword(s):

Crack Propagation ◽

Structural Integrity ◽

Crack Propagation Rate ◽

Fatigue Loading ◽

Propagation Rate ◽

Operating Conditions ◽

Impact Testing ◽

Mode I ◽

Mode I Crack ◽

Constant Amplitude

The T-90 Calima is a low-wing monoplane aircraft. Its structure is mainly composed of different components of composite materials, which are mainly bonded by using adhesive joints of different thicknesses. The T-90 Calima is a trainer aircraft; thus, adverse operating conditions such as hard landings, which cause impact loads, may affect the structural integrity of aircrafts. As a result, in this study, the mode I crack propagation rate of a typical adhesive joint of the aircraft is estimated under impact and constant amplitude fatigue loading. To this end, effects of adhesive thickness on the mechanical performance of the joint under quasistatic loading conditions, impact and constant amplitude fatigue in double cantilever beam (DCB) specimens are experimentally investigated. Cyclic impact is induced using a drop-weight impact testing machine to obtain the crack propagation rate (da/dN) as a function of the maximum strain energy release rate (GImax) diagram; likewise, this diagram is also obtained under constant amplitude fatigue, and both diagrams are compared to determine the effect of each type of loading on the structural integrity of the joint. Results reveal that the crack propagation rate under impact fatigue is three orders of magnitude greater than that under constant amplitude fatigue.

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Crack Propagation Behavior of a Ni-Based Single-Crystal Superalloy during In Situ SEM Tensile Test at 1000 °C

Crystals ◽

10.3390/cryst10111047 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1047

Author(s):

Wenxiang Jiang ◽

Xiaoyi Ren ◽

Jinghao Zhao ◽

Jianli Zhou ◽

Jinyao Ma ◽

...

Keyword(s):

Crack Propagation ◽

Tensile Test ◽

Single Crystal ◽

Crack Propagation Rate ◽

Propagation Rate ◽

Single Crystal Superalloy ◽

Propagation Path ◽

Propagation Behavior ◽

Crack Propagation Behavior

An in situ scanning electron microscope (SEM) tensile test for Ni-based single-crystal superalloy was carried out at 1000 °C. The stress displacement was obtained, and the yield strength and tensile strength of the superalloy were 699 MPa and 826 MPa, respectively. The crack propagation process, consisting of Model I crack and crystallographic shearing crack, was determined. More interestingly, the crack propagation path and rate affected by eutectics was directly observed and counted. Results show that the coalescence of the primary crack and second microcrack at the interface of a γ/γ′ matrix and eutectics would make the crack propagation rate increase from 0.3 μm/s to 0.4 μm/s. On the other hand, crack deflection decreased the rate to 0.05 μm/s. Moreover, movement of dislocations in front of the crack was also analyzed to explain the different crack propagation behavior in the superalloy.

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