Fatigue crack growth rate in underwater wet welds: out of water evaluation

Arias, Ariel Rodriguez; Bracarense, Alexandre Queiróz

doi:10.1080/09507116.2016.1218607

Cited by 11 publications

(11 citation statements)

References 5 publications

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“…During rotating, tensile and compressive loads reversed periodically so that the initial crack will propagate until the material experienced the transition between fatigue and over load, and finally static failure occurs. Propagation of crack will be faster when porosities exists [23,24]. Due to the porosity of the underwater welded joint, as seen in Figures 16, 17, and 18, it has lower fatigue strength than the air welded joint.…”

Section: Fatigue Lifementioning

confidence: 99%

Fatigue life of underwater wet welded low carbon steel SS400

Muhayat

Matien

Sukanto

et al. 2020

Heliyon

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Underwater welding is widely used for maintenance and repairs of underwater structures such as undersea pipes, offshore structures and nuclear power plants. In practice, underwater welding has the disadvantage related to high cooling rate and unstable welding arc due to the water hydrostatic pressure. This affects the microstructure and mechanical properties of underwater welded joints. Many of previous research works on underwater welding have been carried out only on a laboratory scale in shallow water depth, whereas underwater welding was used to weld in the depth of the water with a metre scale. Undersea structures experience fatigue load due to the fluctuation force of water flow. Therefore, this study aims to determine the effect of water depth on the fatigue life of underwater welded joints. Low carbon steel SS400 specimens were welded underwater with depths of 2.5 m, 5 m and 10 m. The air welded joint was also evaluated for comparison purposes. Fatigue life was evaluated according to the ASTM E466 standard by using a rotary bending machine. Furthermore, tensile test, micro hardness measurement and microstructure evaluation were also conducted for gathering supporting data. The fatigue and tensile strength of the air welded joints were higher than those of the underwater welded joints. The porosities caused by the dissolved hydrogen gas, carbon (monoxide and dioxide) gases and water vapor in weld metal of the underwater welded joints decreased the fatigue and tensile strength. An interesting phenomenon on the underwater welded joints was that the deeper the water level, the higher became the fatigue, tensile strength as well as hardness. Based on the microstructure analysis, the number of acicular ferrite structures in weld metal increased as the water level depth increased.

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Section: Fatigue Lifementioning

confidence: 99%

Fatigue life of underwater wet welded low carbon steel SS400

Muhayat

Matien

Sukanto

et al. 2020

Heliyon

View full text Add to dashboard Cite

show abstract

“…The load-bearing structures of such vessels and installations are often made of high-strength steels [1,2], which pose considerable challenges to welders and the welding processes to obtain the welds exhibiting high levels of strength, ductility, and impact toughness [3,4]. A further issue is that underwater wet welding is susceptible to weld defects like hydrogen-assisted cold cracking, porosity, slag inclusions, and delayed hydrogen embrittlement [5][6][7][8][9][10]. Consequently, underwater wet welding has found only limited use for critical applications, which requires further study of the mechanism of the appearance of defects.…”

Section: Introductionmentioning

confidence: 99%

Metallurgical Model of Diffusible Hydrogen and Non-Metallic Slag Inclusions in Underwater Wet Welding of High-Strength Steel

Parshin

Levchenko²,

Maystro

2020

Metals

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High susceptibility to cold cracking induced by diffusible hydrogen and hydrogen embrittlement are major obstacles to greater utilization of underwater wet welding for high-strength steels. The aim of the research was to develop gas–slag systems for flux-cored wires that have high metallurgical activity in removal of hydrogen and hydroxyl groups. Thermodynamic modeling and experimental research confirmed that a decrease in the concentration of diffusible hydrogen can be achieved by reducing the partial pressure of hydrogen and water vapor in the vapor–gas bubble and by increasing the hydroxyl capacity of the slag system in metallurgical reactions leading to hydrogen fluoride formation and ionic dissolution of hydroxyl groups in the basic fluorine-containing slag of a TiO2–CaF2–Na3AlF6 system.

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“…It is proven by radiographic test which showed that underwater wet weld metal in water flow of 2 m/s has more weld defects in the form of undercuts and porosity. According to Ottersboc et al [34], undercut defects reduce the strength of a material, while Fomin et al [35] and Arias [36] stated that porosity can accelerate the propagation of fatigue cracks. Another factor that affects the increase of the fatigue cracks growth rate is an inclusion in underwater wet welding.…”

Section: Resultsmentioning

confidence: 99%

Effect of water flow and depth on fatigue crack growth rate of underwater wet welded low carbon steel SS400

et al. 2021

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Underwater wet welding (UWW) is widely used in repair of offshore constructions and underwater pipelines by the shielded metal arc welding (SMAW) method. They are subjected the dynamic load due to sea water flow. In this condition, they can experience the fatigue failure. This study was aimed to determine the effect of water flow speed (0 m/s, 1 m/s, and 2 m/s) and water depth (2.5 m and 5 m) on the crack growth rate of underwater wet welded low carbon steel SS400. Underwater wet welding processes were conducted using E6013 electrode (RB26) with a diameter of 4 mm, type of negative electrode polarity and constant electric current and welding speed of 90 A and 1.5 mm/s respectively. In air welding process was also conducted for comparison. Compared to in air welded joint, underwater wet welded joints have more weld defects including porosity, incomplete penetration and irregular surface. Fatigue crack growth rate of underwater wet welded joints will decrease as water depth increases and water flow rate decreases. It is represented by Paris's constant, where specimens in air welding, 2.5 m and 5 m water depth have average Paris's constant of 8.16, 7.54 and 5.56 respectively. The increasing water depth will cause the formation of Acicular Ferrite structure which has high fatigue crack resistance. The higher the water flow rate, the higher the welding defects, thereby reducing the fatigue crack resistance.

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Fatigue crack growth rate in underwater wet welds: out of water evaluation

Cited by 11 publications

References 5 publications

Fatigue life of underwater wet welded low carbon steel SS400

Fatigue life of underwater wet welded low carbon steel SS400

Metallurgical Model of Diffusible Hydrogen and Non-Metallic Slag Inclusions in Underwater Wet Welding of High-Strength Steel

Effect of water flow and depth on fatigue crack growth rate of underwater wet welded low carbon steel SS400

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