Fatigue crack propagation in API 5L X-70 pipeline steel longitudinal welded joints under constant and variable amplitudes

Beltrão, M.; Castrodeza, Enrique Mariano; Bastian, Fernando Luíz

doi:10.1111/j.1460-2695.2010.01521.x

Cited by 19 publications

(7 citation statements)

References 27 publications

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“…Therefore, the FCGRs in the FZ and WZ are almost the same as that in the BM at high R-ratios. This reveals that the FCGRs of the Q345 steel welded joint is same as results obtained by Neves et al 29 for welded joints of an API X-70 pipeline steel. The results show that the FCPGs in Paris region is not affected by the microstructure of the welded joints for R = 0.5.…”

Section: Discussionsupporting

confidence: 88%

The effect of microstructures on fatigue crack growth in Q345 steel welded joint

Xiong

2012

Fatigue Fract Eng Mat Struct

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A B S T R A C TIt is a traditional that the fatigue crack growth behavior is sensitive to microstructure in threshold regime, while it is sensitive to R-ratio in Paris regime. Fatigue test is carried out for welded joints of a Q345 steel where the compact tension specimens with 3.8 and 12.5 mm thickness are used, and comparisons of fatigue crack growth behavior between base metal and a few different locations in the welded joint are considered in Paris regime. Welding residual stresses are removed by heat treatment to focus the study on the microstructural effect. It is shown that fatigue crack growth rate (FCGR) in the base metal is not sensitive to R-ratio, but the FCGR increases in the overheated zone, the fusion zone and the weld metal zone with R-ratio increasing. To the low R-ratio, FCGR in the three zones is smaller than that in the base metal, but they approximate the same with base metal under the high R-ratio. The mechanism of fatigue crack growth is analyzed through crack path in microstructures and SEM fractograph. The coarse-grained ferrite in the base metal is of benefit to relaxation of the average stress at the crack tip, and the fatigue crack growth predicts branching and deflection within above different locations in the welded joint. These tortuous crack paths with crack branching and deflection will promote crack closure as well as crack-tip stress shielding and then resulted in higher crack growth resistance.a 0 = distance between the notch root and the line of action of the externally applied load a f = crack length measured from the notch root at the termination of test f = loading frequency K max , P max = maximum stress intensity factor, maximum load K min , P min = minimum stress intensity factor, minimum load K op , P op = opening stress intensity factor, opening load K s = stress intensity factor corresponding to the stress shielding effect K eff = effective stress intensity factor range K = applied stress intensity range K tip = stress intensity factor range experienced by the crack tip K eff,tip = crack-tip effective stress intensity factor range Correspondence: Y. Xiong.

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Section: Discussionsupporting

confidence: 88%

The effect of microstructures on fatigue crack growth in Q345 steel welded joint

Xiong

2012

Fatigue Fract Eng Mat Struct

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“…For low values of ΔK this phenomenon as more marked by the crack tip plasticity following its advance (thus forming a wake plasticized). These results are in good agreement with the results of Beltrao et al [50] but, they noticed that the fatigue crack propagation is get more independent from the high load ratio values(R=0.5)…”

Section: Fatigue Testssupporting

confidence: 92%

Fatigue crack propagation in welded joints X70

Deliou

Bouchouicha

2018

Frattura Ed Integrità Strutturale

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Structural failure assessment approaches take into account local parameters, specimen geometry, loading and material. In the case of welded joints, in addition to these parameters, consideration must be given to the effect of the heterogeneity of properties due to welding. The objective of our work is to study the fatigue crack propagation of welded joint in API X70 pipeline steel. This experimental study focused on welded joints in the different parts, base metal, weld metal and heat affected zone. The concepts of fracture mechanics are used to analyze the harmfulness of defects in welded joints and the main part of fatigue life falls on the crack propagation. The results obtained show that the fatigue crack propagation rate of cracks in the heat affected zone is delayed compared to the other zones. The effect of the microstructure and the quality of submerged arc welding of the studied X70 steel are significant. Tensile tests, hardness and measurement of energetically parameters complemented this work.

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“…For production of pipes for oil and gas pipelines, highfrequency welding (HFW) and arc welding technologies are used. Many practical studies are devoted to studying the characteristics of fatigue failure, which, according to the authors [1][2][3][4][5][6], is one of the main requirements for pipeline integrity.…”

Section: Introductionmentioning

confidence: 99%

Sress-corrosion cracking under cathodic protection of low alloy steel joints with high frequency weld and arc weld

Nyrkova

Goncharenko

Osadchuk

et al. 2022

Phys. Chem. Solid St.

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According to the results of complex electrochemical, corrosion-mechanical and fractographic studies, the existence of three potential regions, in which the stress-corrosion cracking (SCC) of 17G1S (17G1S-U) steel in the NS4 model soil electrolyte occurs by different mechanisms was established and experimentally confirmed: at potentials positively than -0.8 V – by the mechanism of local anodic dissolution, at potentials region from -0.8 V to -0.98 V – by the mixed mechanism, at potentials less than -0.98 V by hydrogen breaking mechanism. The susceptibility to SCC of high-frequency weld joints, estimated by the coefficient of KS, in the potential range from the corrosion potential to -1.2 V increases (KS increases from 1.1 to 1.8), which is less intense than for steel 17G1S/17G1S-U (KS increases from 1.1 to 2.8), for arc weld joints – does not change much enough (KS increases from 1.1 to 1.3). The validity of KS coefficient introduced for the base metal for comparative assessment of the susceptibility to SCC of welded joints, is provided in case that there are no defects in the welds and SCC occurs on base metal.

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Fatigue crack propagation in API 5L X-70 pipeline steel longitudinal welded joints under constant and variable amplitudes

Cited by 19 publications

References 27 publications

The effect of microstructures on fatigue crack growth in Q345 steel welded joint

The effect of microstructures on fatigue crack growth in Q345 steel welded joint

Fatigue crack propagation in welded joints X70

Sress-corrosion cracking under cathodic protection of low alloy steel joints with high frequency weld and arc weld

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