Low Cycle Fatigue Behaviour of API 5L X65 Pipeline Steel at Room Temperature

Fatoba, Olusegun; Akid, Robert

doi:10.1016/j.proeng.2014.06.263

Cited by 24 publications

(16 citation statements)

References 8 publications

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“…The combined isotropic-kinematic hardening elastic-plastic material model was utilised incorporating the cyclic true stress–strain curve of X65 steel that is published in the literature. 37 The C3D10 element (i.e. a 10-node second-order tetrahedral element) has been used in this work to mesh the model.…”

Section: Cyclic Stress–strain Analysismentioning

confidence: 99%

“…The material was provided by the industrial sponsor. The chemical composition was obtained by optical emission spectroscopy at The Welding Institute (TWI Ltd.) and the mechanical properties obtained from the literature, 37 both of which are shown in Tables 1 and 2 respectively. Although the composition of the steel used in this work is not exactly the same as that given for X65 steel in Fatoba and Akid, 37 the difference does not affect the mechanical properties of the material.…”

Section: Materials and Specimensmentioning

confidence: 99%

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Fatigue behaviour of corrosion pits in X65 steel pipelines

Farhad

Zhang

Smyth-Boyle

2018

Proceedings of the Institution of Mechanical Engineers, Part C:

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Corrosion pits are a form of geometrical discontinuity that lead to stress and strain concentration in engineering components, resulting in crack initiation under service loading conditions and ultimately fracture and failure. Initiation and propagation of cracks in offshore pipelines can lead to loss of containment and environmental and commercial impacts. In order to prevent such failures, tools to predict the structural integrity of pipelines need to be improved. This work investigates the fatigue behaviour of corrosion pits in API-5L X65 grade steel pipeline utilising numerical and analytical methods. Firstly, load-controlled fatigue tests were carried out on smooth X65 steel samples to establish S–N data. Secondly, local stress–strain behaviour at corrosion pits and its effect on fatigue crack initiation were investigated using elastic-plastic finite element analysis of samples containing a single corrosion pit under cyclic loading. Analysis of stabilised stress–strain hysteresis loops at corrosion pits showed that the local stress ratio at the pit changes from 0.1 to −0.4 while the applied stress amplitude increases with the same stress ratio of 0.1. Analytical methods were also used to predict the local maximum stress and strain at the pit, which showed a similar local stress ratio to the finite element analysis result but lower stress and strain ranges. Finally, fatigue crack initiation life was predicted using the combination of finite element stress and strain analysis and the Smith–Watson–Topper strain–life approach. An advantage of this method for life estimation is that this approach considers the local stress and strains at corrosion pits rather than applied stress.

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Section: Cyclic Stress–strain Analysismentioning

confidence: 99%

Section: Materials and Specimensmentioning

confidence: 99%

Fatigue behaviour of corrosion pits in X65 steel pipelines

Farhad

Zhang

Smyth-Boyle

2018

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…After the second repair, the properties of the welded joints do not meet the acceptability criteria defined by the standards applied by API. Fatoba [28] studied the oligocyclic fatigue behavior of API 5L X65 pipeline steel at room temperature. The author has shown that the increase in the amplitude of total deformation has the effect of decreasing the life of fatigue oligocyclic, and the amplitude of stress increases with the amplitude of plastic deformation.…”

Section: Introductionmentioning

confidence: 99%

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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“…The fatigue mechanism starts with the formation of cracks in individual strut and their propagation, leading to further crushing of the foam and the loosing of its stiffness. The behavior of the foam subjected to low cycle loading might be predicted using the Coffin-Manson relation (Equation (1)) [20,21]:…”

Section: Investment Casting Of Metallic Foamsmentioning

confidence: 99%

Aluminum Inserts for Enhancing Heat Transfer in PCM Accumulator

et al. 2020

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Phase change materials (PCMs) are applied in heat storage units, as they are able to accumulate the energy in the form of the latent heat of fusion. Thus, they can be used in recovering the excess of heat from various industrial processes. Their main weakness is their low thermal conductivity coefficient, which strongly limits their usage. In this paper, the benefits of the application of metallic inserts in heat storage PCM-based units were elaborated. Two kinds of Al–Si spatial elements (foams and honeycomb structures) were produced with the use of means of the investment casting method. Key factors influencing the technological process were established. The surface’s roughness was measured in order to compare the obtained structures with their patterns in terms of the casting’s accuracy. The compressive strength of the samples was tested, and their fatigue resistance was considered. The thermal performance of manufactured inserts in the PCM (paraffin)-based accumulator, supported by the calculation of heat fluxes, was analyzed and adjusted. Finally, further optimization was conducted in terms of the volume ratio of the metal insert to the PCM. Metallic inserts were found to significantly affect the performance of the entire energy storage system, as their use results in reduced charging time, a longer heat release time, increased maximum temperature, and a significant reduction in the temperature gradient in the heat storage unit.

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Low Cycle Fatigue Behaviour of API 5L X65 Pipeline Steel at Room Temperature

Cited by 24 publications

References 8 publications

Fatigue behaviour of corrosion pits in X65 steel pipelines

Fatigue behaviour of corrosion pits in X65 steel pipelines

Fatigue crack propagation in welded joints X70

Aluminum Inserts for Enhancing Heat Transfer in PCM Accumulator

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