X-Ray Diffraction Study of Microstructural Changes During Fatigue Damage Initiation in Steel Pipes

2012 ◽  
Author(s):  
Bianca Pinheiro ◽  
Jacky Lesage ◽  
Ilson Pasqualino ◽  
Noureddine Benseddiq ◽  
Edoardo Bemporad
Keyword(s):  
Residual Stresses ◽  
Fatigue Damage ◽  
Fatigue Tests ◽  
X Ray Diffraction ◽  
Peak Displacement ◽  
Microstructural Changes ◽  
X Ray ◽  
Steel Pipes ◽  
Damage Initiation ◽  
Grade Steel

The present work aims to evaluate the microstructural mechanisms associated with the initiation of fatigue damage in steels used in the petroleum industry. Microdeformations and residual stresses (macrostresses) are evaluated by X-ray diffraction in real time during alternating bending fatigue tests performed on samples taken from an API 5L X60 grade steel pipe. Microdeformations are evaluated from measurements of the full width at half maximum (FWHM) of the diffraction peak and residual stresses are estimated from the peak displacement. The evolution of microdeformations shows three regular successive stages of changes. The amplitude of variation of each stage is intensified with increasing stress amplitude, while the duration is reduced. A similar evolution is found for residual stresses, whose stages of changes have nearly the same durations as those of microdeformations. Changes in density and distribution of dislocations are observed by transmission electron microscopy combined with the technique of focused ion beam. To understand the role of the initial structure, fatigue tests on annealed samples are performed under the same test conditions. Again, three stages of changes are observed, but with an increase in microdeformations instead of a decrease during the first stage due to the initial state of the dislocation network. The results are very encouraging for the consideration of microstructural changes measured by X-ray diffraction in the development of a future indicator of fatigue damage initiation in API 5L X60 grade steel pipes.

X-Ray Diffraction Study of Microstructural Changes During Fatigue Damage in Steel Pipelines

2012 ◽  
Author(s):  
Bianca Pinheiro ◽  
Jacky Lesage ◽  
Ilson Pasqualino ◽  
Noureddine Benseddiq ◽  
Edoardo Bemporad
Keyword(s):  
Fatigue Damage ◽  
Fatigue Behavior ◽  
Ion Beam ◽  
Fatigue Tests ◽  
X Ray Diffraction ◽  
Microstructural Changes ◽  
X Ray ◽  
Steel Pipes ◽  
Damage Initiation ◽  
Three Stages

Steel pipes used for oil and gas exploitation undergo the action of cyclic loads that can cause their failure by fatigue. A consistent evaluation of the fatigue behavior should take into account the micromechanisms of fatigue damage initiation, which precede macroscopic cracking and macrocrack propagation. In this work, microstructural changes in terms of variations in microdeformations and residual stresses (macrostresses) are evaluated by X-ray diffraction in real time during alternating bending fatigue tests performed on samples taken from an API 5L X60 grade steel pipe. Three stages of microstructural changes are detected. It is found that their amplitudes and durations are proportional to the level of alternating stress applied. Changes in density and distribution of dislocations are observed by transmission electron microscopy combined with the technique of focused ion beam. To understand the role of the initial dislocation structure, fatigue tests on annealed samples are performed under the same test conditions. Again, three stages of changes are observed, but with an increase in microdeformations during the first stage instead of a decrease as found for as-machined samples, suggesting the influence of the initial state of the dislocation network. The results obtained are very encouraging for the consideration of microstructural evolutions in the development of an indicator of fatigue damage initiation in steel pipes.

X-ray diffraction study of microstructural changes during fatigue damage initiation in steel pipes

2012 ◽  
Vol 532 ◽  
pp. 158-166 ◽  
Author(s):  
B. Pinheiro ◽  
J. Lesage ◽  
I. Pasqualino ◽  
N. Benseddiq ◽  
E. Bemporad
Keyword(s):  
Diffraction Study ◽  
Fatigue Damage ◽  
X Ray Diffraction ◽  
Microstructural Changes ◽  
X Ray ◽  
Steel Pipes ◽  
Damage Initiation

Assessment of Fatigue Damage Initiation in Oil and Gas Steel Pipes

2011 ◽  
Author(s):  
Bianca Pinheiro ◽  
Jacky Lesage ◽  
Ilson Pasqualino ◽  
Noureddine Benseddiq
Keyword(s):  
Fatigue Damage ◽  
Oil And Gas ◽  
Fatigue Behavior ◽  
Diffraction Method ◽  
Fatigue Tests ◽  
Uniaxial Tensile ◽  
Good Prediction ◽  
Steel Pipes ◽  
Damage Initiation ◽  
Grade Steel

Steel pipe structures used in oil and gas industry, such as drill pipes, rigid risers and pipelines, undergo the action of cyclic loadings that can cause their failure by fatigue. These structures are made of high strength steels, such as API 5L grades X for instance. A consistent evaluation of the fatigue behavior should fundamentally be based on a local approach, in the dislocation scale, and take into account the micromechanisms of fatigue damage initiation, including microdeformations and microstructural changes, which precede the macrocrack propagation leading to final failure. In this work, the microstructural mechanisms of fatigue damage initiation in API 5L X60 grade steel pipes are investigated. Material properties of API 5L X60 steel are estimated according to chemical composition analyses, microscopic analyses, uniaxial tensile tests and Vickers micro-hardness tests. Samples are submitted to fatigue tests with reversed stress bending loadings. Microdeformations and residual stresses are measured with the aid of the X-ray diffraction method in real-time during fatigue tests. A numerical model is developed to reproduce the fatigue test loadings. The aim of the work is to provide ground for the development of a microstructural criterion for fatigue damage initiation in API 5L X60 grade steel pipes from the obtained experimental results. This criterion could allow a good prediction of the residual life of steel pipes previously submitted to fatigue loadings, before macroscopic cracking, and help to increase the reliability of oil and gas pipes.

Residual Stress in Railway Rails by IP/cosα Method

2006 ◽  
Vol 524-525 ◽  
pp. 381-386 ◽  
Author(s):  
Toshihiko Sasaki ◽  
Shunichi Takahashi ◽  
Kengo Iwfuchi ◽  
Yukio Satoh ◽  
Yoshikazu Kanematsu ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Fatigue Damage ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
X Ray Diffraction ◽  
Present Measurement ◽  
X Ray ◽  
Fundamental Experiment

In this study, a new portable X-ray stress analyzer was designed and manufactured. The purpose of its use is to evaluate the rolling contact fatigue damage in rails for establishing an effective rail maintenance method. An image plate was used in this analyzer for detecting diffracted X-ray beams. The cosα method was adopted for X-ray stress analysis from X-ray diffraction data. A fundamental experiment was made first for examning the present measurement system. Residual stresses in rails used in service for six years were also investigated in this study.

scholarly journals High Cycle Fatigue Damage Evaluation of Steel Pipelines Based on Microhardness Changes During Cyclic Loads

2017 ◽  
Author(s):  
Geovana Drumond ◽  
Bianca Pinheiro ◽  
Ilson Pasqualino ◽  
Francine Roudet ◽  
Didier Chicot ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Steel Structures ◽  
Material Surface ◽  
Cyclic Loads ◽  
X Ray Diffraction ◽  
Microstructural Changes ◽  
X Ray ◽  
Microcrack Initiation ◽  
Non Destructive

Fatigue is a major cause of failures concerning metal structures, being capable of causing catastrophic damage to the environment and considerable financial loss. Steel pipelines used in oil and gas industry for hydrocarbon transportation, for instance, are submitted to the action of cyclic loads, being susceptible to undergo fatigue failures. The phenomenon of metal fatigue is a complex process comprising different successive mechanisms. In general, four stages can be identified, representing microcrack initiation (nucleation), microcracking, macrocrack propagation, and final fracture. Fatigue damage prior to nucleation of microcracks is primarily related to localized plastic strain development at or near material surface during cycling. The microhardness of the material shows its ability to resist microplastic deformation caused by indentation or penetration, and is closely related to the material plastic slip capacity. Therefore, the study of changes in material surface microhardness during the different stages of fatigue process can estimate the evolution of the material resistance to microplastic deformations and, consequently, provide relevant information about the cumulated fatigue damage on the surface. The present work is part of a research study being carried out with the aim of proposing a new method based on microstructural changes, represented by a fatigue damage indicator, to predict fatigue life of steel structures submitted to cyclic loads, before macroscopic cracking. In a previous work, the X-ray diffraction technique was used to evaluate these changes. This technique presents several advantages, since it is non-destructive and concerns the surface and subsurface of the material, where major microstructural changes take place during fatigue. The most important parameter obtained by this technique is the full width at half maximum (FWHM) of the diffraction peak, which can provide information about the dislocation network density and estimate microdeformations. It was found that the evolution of this parameter with cycling presents three different stages, associated to the mechanisms of microcrack initiation, microcracking, macrocrack propagation, respectively. Here, the fatigue damage of pipeline steels is evaluated through microhardness testing. Different stages of changes in microhardness are also found and they are correlated to those observed with the X-ray technique and also with transmission electron microscopic (TEM) images from experimental tests performed with a similar material. This correlation can help to corroborate the X-ray diffraction results previously obtained and recommend then this non-destructive technique as the base of the method for predicting fatigue life of steel structures proposed here.

Toward a Fatigue Life Assessment of Steel Pipes Based on X-Ray Diffraction Measurements

2015 ◽  
Author(s):  
Bianca Pinheiro ◽  
Jacky Lesage ◽  
Ilson Pasqualino ◽  
Noureddine Benseddiq ◽  
Edoardo Bemporad
Keyword(s):  
Residual Stresses ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Petroleum Industry ◽  
Fatigue Tests ◽  
Material Behavior ◽  
Life Assessment ◽  
Initial Structure ◽  
X Ray Diffraction ◽  
X Ray

The present work aims to evaluate the microstructural mechanisms associated with the initiation of fatigue damage of steels used in the petroleum industry. Microdeformations and residual stresses (macrostresses) are evaluated by X-ray diffraction in real time during alternating bending fatigue tests performed on samples taken from an API 5L X60 grade steel pipe. Samples under two different conditions are considered: as-machined and annealed. Microdeformations and residual stresses are estimated from measurements of the full width at half maximum (FWHM) and displacement of the diffraction peak, respectively. The evolution of microdeformations shows three distinct stages (Stages 1–3). Increasing stress amplitude accentuates variations in FWHM and reduces the duration of each stage. Similar variations are observed for the residual stresses. The results from annealed samples allow the comprehension of the role of the initial structure. Changes in the density and distribution of dislocations are observed by transmission electron microscopy using the technique of focused ion beam. Cyclic uniaxial tests are carried out in order to evaluate the material behavior, in both as-machined and annealed conditions, under cyclic loadings. The cyclic material behavior is correlated to the evolution of microdeformations observed during the fatigue bending tests.

scholarly journals X-ray Determination of Compressive Residual Stresses in Spring Steel Generated by High-Speed Water Quenching

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1154
Author(s):  
Diego E. Lozano ◽  
George E. Totten ◽  
Yaneth Bedolla-Gil ◽  
Martha Guerrero-Mata ◽  
Marcel Carpio ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
High Speed ◽  
Spring Steel ◽  
X Ray Diffraction ◽  
Laboratory Equipment ◽  
X Ray ◽  
Water Chamber ◽  
Hardened Case ◽  
Compressive Residual Stresses

Automotive components manufacturers use the 5160 steel in leaf and coil springs. The industrial heat treatment process consists in austenitizing followed by the oil quenching and tempering process. Typically, compressive residual stresses are induced by shot peening on the surface of automotive springs to bestow compressive residual stresses that improve the fatigue resistance and increase the service life of the parts after heat treatment. In this work, a high-speed quenching was used to achieve compressive residual stresses on the surface of AISI/SAE 5160 steel samples by producing high thermal gradients and interrupting the cooling in order to generate a case-core microstructure. A special laboratory equipment was designed and built, which uses water as the quenching media in a high-speed water chamber. The severity of the cooling was characterized with embedded thermocouples to obtain the cooling curves at different depths from the surface. Samples were cooled for various times to produce different hardened case depths. The microstructure of specimens was observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) was used to estimate the magnitude of residual stresses on the surface of the specimens. Compressive residual stresses at the surface and sub-surface of about −700 MPa were obtained.

scholarly journals X-ray diffraction analysis of the structure and residual stresses of W/Cu multilayers

2006 ◽  
Vol 201 (7) ◽  
pp. 4372-4376 ◽  
Author(s):  
B. Girault ◽  
P. Villain ◽  
E. Le Bourhis ◽  
P. Goudeau ◽  
P.-O. Renault
Keyword(s):  
Residual Stresses ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
X Ray

Investigation of Residual Stress/Strain and Texture in a Large Dissimilar Metal Weld Using Synchrotron Radiation and Neutrons

2013 ◽  
Vol 772 ◽  
pp. 193-199 ◽  
Author(s):  
Carsten Ohms ◽  
Rene V. Martins
Keyword(s):  
Synchrotron Radiation ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Large Scale ◽  
High Energy ◽  
X Ray Diffraction ◽  
Butt Weld ◽  
X Ray ◽  
Component Size ◽  
Thin Slice

Bi-metallic piping welds are frequently used in light water nuclear reactors to connect ferritic steel pressure vessel nozzles to austenitic stainless steel primary cooling piping systems. An important aspect for the integrity of such welds is the presence of residual stresses. Measurement of these residual stresses presents a considerable challenge because of the component size and because of the material heterogeneity in the weld regions. The specimen investigated here was a thin slice cut from a full-scale bi-metallic piping weld mock-up. A similar mock-up had previously been investigated by neutron diffraction within a European research project called ADIMEW. However, at that time, due to the wall thickness of the pipe, stress and spatial resolution of the measurements were severely restricted. One aim of the present investigations by high energy synchrotron radiation and neutrons used on this thin slice was to determine whether such measurements would render a valid representation of the axial strains and stresses in the uncut large-scale structure. The advantage of the small specimen was, apart from the easier manipulation, the fact that measurement times facilitated a high density of measurements across large parts of the test piece in a reasonable time. Furthermore, the recording of complete diffraction patterns within the accessible diffraction angle range by synchrotron X-ray diffraction permitted mapping the texture variations. The strain and stress results obtained are presented and compared for the neutron and synchrotron X-ray diffraction measurements. A strong variation of the texture pole orientations is observed in the weld regions which could be attributed to individual weld torch passes. The effect of specimen rocking on the scatter of the diffraction data in the butt weld region is assessed during the neutron diffraction measurements.

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