Hydrogen diffusion and hydrogen influenced critical stress intensity in an API X70 pipeline steel welded joint – Experiments and FE simulations

2012 ◽  
Vol 37 (15) ◽  
pp. 11474-11486 ◽  
Author(s):  
Vigdis Olden ◽  
Antonio Alvaro ◽  
Odd M. Akselsen
Keyword(s):  
Stress Intensity ◽  
Critical Stress ◽  
Hydrogen Diffusion ◽  
Welded Joint ◽  
Pipeline Steel ◽  
X70 Pipeline Steel ◽  
Fe Simulations

Effect of cold rolling on hydrogen diffusion and trapping in X70 pipeline steel

2020 ◽  
pp. 1-28
Author(s):  
Alen Thomas ◽  
Jerzy Szpunar
Keyword(s):  
Cold Rolling ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Pipeline Steel ◽  
Effective Diffusion ◽  
Diffusion Path ◽  
X70 Pipeline Steel ◽  
Diffusion Parameters ◽  
Intensity Changes ◽  
Diffusion Intensity

Abstract In this investigation, we prepared samples with five different grain misorientations by cold rolling an X70 pipeline steel plate. The hydrogen permeation and hydrogen visualization experiments were used to compute the diffusion parameters and to reveal the diffusion path in steel samples. The dual-polarized permeation experiment allowed us to show that permeability and effective diffusion coefficient were decreased with an increase in misorientation. Hence, the total and irreversible trapping sites were also raised with the extent of deformation in the steel. On the other hand, the visualization study permitted us to show that hydrogen diffusion intensity changes within the microstructure. The diffusion intensity increases in the order of non-deformed grains, grain boundaries and deformed grains with deformed grains as the easiest path for hydrogen diffusion.

The Strengthened Mechanism of X70 Pipeline Steel Welded Joints by Laser Shock Processing

2010 ◽  
Vol 44-47 ◽  
pp. 3114-3118
Author(s):  
De Jun Kong ◽  
Chao Zheng Zhou
Keyword(s):  
Shock Wave ◽  
Residual Stress ◽  
Welded Joint ◽  
Pipeline Steel ◽  
Laser Shock ◽  
Laser Shock Processing ◽  
X70 Pipeline Steel ◽  
Surface Residual Stresses ◽  
Laser Shock Wave ◽  
Shock Processing

The X70 pipeline steel welded joint was processed to strengthen with laser shock wave, the structures of welded joint by laser shock wave were observed with Scanning Electric Microscope (SEM), and its surface residual stresses was analyzed with X-ray diffraction (XRD), the residual stress distributions of welded joint by laser shock processing were discussed, and the strengthened mechanism of X70 pipeline welded joint by laser shock processing was investigated. The experimental results shown that the phenomenon of grain fine is produced in the surface of X70 pipeline steel welded joint by laser shock processing, and compressive residual stress is formed in its surface layer, and improves the distribution of residual stress, which is benefit to increasing the capability of stress corrosion resistance for X70 pipeline steel welded joint.

Effect of Laser Shock Processing on Sulfide Stress Corrosion Cracking of X70 Pipeline Steel Welded Joint

2010 ◽  
Vol 44-47 ◽  
pp. 451-455
Author(s):  
Jun Feng Pei ◽  
Jun Ning Liu ◽  
Wei Ying He
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Welded Joint ◽  
Pipeline Steel ◽  
Corrosion Cracking ◽  
Laser Shock Processing ◽  
X70 Pipeline Steel ◽  
Sulfide Stress ◽  
Shock Processing ◽  
Sulfide Stress Corrosion Cracking

Laser shock processing (LSP) is a new technique for metal surface strengthening by which residual compressive stress in the superficial layer can be induced to greatly improve the stress corrosion resistance property. The effect of LSP on sulfide stress corrosion cracking (SSCC) of X70 pipeline steel welded joint has been studied in this paper. A convergent lens is used to deliver 20 J, 20 ns laser pulses by a Q switch Nd:YAG laser, operating at 10 Hz. The pulses are focused to a diameter of 3 mm onto samples. The power density of laser at the surface of the sample was about 5 GW/cm2. The surface residual stress level after LSP is much higher than before. SSCC behavior of X70 pipeline steel welded joint was investigated using slow strain rate testing (SSRT) in H2S solution. Morphology of X70 pipeline steel fracture surface was observed by scanning electron microscope (SEM). It has been demonstrated that LSP is an effective surface treatment technique to improve the stress corrosion cracking (SCC) resistance properties of X70 pipeline steel welded joints.

Simulation of hydrogen diffusion in welded joint of X80 pipeline steel

2014 ◽  
Vol 21 (12) ◽  
pp. 4432-4437 ◽  
Author(s):  
Chun-yan Yan ◽  
Cui-ying Liu ◽  
Gen-yuan Zhang
Keyword(s):  
Hydrogen Diffusion ◽  
Welded Joint ◽  
Pipeline Steel ◽  
X80 Pipeline Steel

Расчетные методы оценки ударной вязкости сварных элементов с трещинами

2020 ◽  
Vol 44 (3) ◽  
pp. 22-36
Author(s):  
Keyword(s):  
Stress Intensity ◽  
Impact Strength ◽  
Welded Joints ◽  
Development Process ◽  
Welded Joint ◽  
Operating Temperature ◽  
Crack Development ◽  
Heterogeneous Structure ◽  
Critical Crack Length ◽  
The Impact

Практика показывает, что для сварных конструкций, эксплуатируемых в условиях Крайнего Севера необходимо уделять внимание работоспособности сварных соединений при низких температурах. Металл сварных соединений в процессе воздействия обработки изменяет свои свойства, снижается ударная вязкость, образуется гетерогенная структура с большой степенью разнозернистости. Чтобы оценивать и иметь возможность правильно контролировать термическое воздействие и последствия сварочного процесса, требуется решить задачу аналитического определения ударной вязкости для всех зон сварного соединения. В настоящей статье представлен инженерный метод оценки ударной вязкости, применимый для любой зоны сварного соединения, в которой имеется острый или особый концентратор напряжений – трещина. Разработанный аналитический метод расчета ударной вязкости отражает качественную и количественную картину взаимосвязи структурно-механических характеристик и работы развития трещины в диапазоне температур 77…300 К. Предложенная схематизация зависимости критического коэффициента интенсивности напряжений от температуры позволила найти коэффициенты, характеризующие свойства материала, и выполнить расчеты изменения предела текучести и предела прочности от температуры эксплуатации. Построены графики зависимости работы развития трещины от температуры эксплуатации для сталей 15ГС и 17ГС, сравнение которых с экспериментальными данными показывает удовлетворительное согласование. Найдено, что при напряжениях предела выносливости отношение работы развития трещины к критической длине трещины постоянно, не зависит от температуры и для сталей 15ГС и 17ГС равно около 10. Ключевые слова: ударная вязкость, работа разрушения, коэффициент интенсивности напряжений, трещина, феррито-перлитная сталь, зона термического влияния. For welded structures under operation in the Far North, attention must be paid to the performance of welded joints at low temperatures. The properties of metal of welded joints are changed in the process of treatment, its toughness decreases, and a heterogeneous structure with a large range of different grain sizes is formed. In order to evaluate and be able to correctly control the thermal effect and the consequences of the welding process, it is necessary to solve the problem of analytical determination of impact strength for all zones of the welded joint. The paper presents an engineering method for evaluation of the impact strength applicable to any area of the welded joint in which there is a sharp or super sharp stress concentrator – a crack. The developed analytical method for calculating the impact strength reflects a qualitative and quantitative codependency of structural and mechanical characteristics and the process of crack development in the temperature range of 77–300 K. The proposed schematization of dependence of the critical coefficient of stress intensity on the temperature made it possible to find coefficients characterizing the properties of the material and to perform calculations of changes in yield strength and tensile strength on operating temperature. Graphs of the crack development process dependency on the operating temperature for 15ГС and 17ГС steels were constructed, and their comparison with experimental data displays satisfactory agreement. It was found that at endurance limit stresses, the ratio of the crack development process to the critical crack length is constant, non-dependent on temperature, and is equal to 10 for 15ГС and 17ГС steels. Keywords: impact strength, fracture work, stress intensity factor, crack, ferrite-pearlite steel, heat affected zone, steel tempering.

STRESS CORROSION CRACK INITIATION BEHAVIOR FOR THE X70 PIPELINE STEEL BENEATH A DISBONDED COATING

2012 ◽  
Vol 48 (10) ◽  
pp. 1267 ◽  
Author(s):  
Zhiying WANG ◽  
Jianqiu WANG ◽  
En-hou HAN ◽  
Wei KE ◽  
Maocheng YAN ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Stress Corrosion ◽  
Stress Corrosion Crack ◽  
Pipeline Steel ◽  
X70 Pipeline Steel ◽  
Disbonded Coating
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