Investigation of the Correlation between Hydrogen Cathodic Charging Conditions and Toughness Properties of Longitudinal Submerged Arc Welded X65 Pipeline Steels

Kyriakopoulou, H. P.; Belntekos, I. D.; Tazedakis, Athanasios; Daniolos, Nikoalos M; Karmiris-Obratański, Panagiotis; Pantelis, D.I.

doi:10.1007/s11665-020-04864-0

Cited by 7 publications

(6 citation statements)

References 42 publications

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“…Therefore, the hydrogen changed the fracture type from ductile to quasi‐cleavage. These results are in accordance with the results reported by other researchers 35,42,77,79,95,98 …”

Section: Resultssupporting

confidence: 94%

“…Fisheyes were noticed in the fracture surface of the base metal specimen (Figure 10F,G), and weld specimen (Figure 11F–H) indicated by orange arrows, demonstrating that the fracture process involved hydrogen diffusion and the steel was saturated with such interstitial 79 . The fisheye‐like morphology is caused by capturing the atomic hydrogen at inclusions 42 . This hydrogen imprisoned is recombined, forming molecular hydrogen under high pressure and thus causing localized deformation of the matrix.…”

Section: Resultsmentioning

confidence: 98%

“…These results are in accordance with the results reported by other researchers. 35,42,77,79,95,98 The fracture presented characteristics of embrittled regions, such as quasi-cleavage facets and the appearance of micro-voids with fisheye morphology. Fisheyes were noticed in the fracture surface of the base metal specimen (Figure 10F,G), and weld specimen (Figure 11F-H) indicated by orange arrows, demonstrating that the fracture process involved hydrogen diffusion and the steel was saturated with such interstitial.…”

Section: Fractography Analysis Of Fracture Toughness Specimensmentioning

confidence: 99%

“…The welding seams hydrogen concentration level is typically more significant than the concentration in the base metal 37‐39 . Some microstructures are more susceptible to HE, such as coarse microstructures, 2,40,41 the interface between the ferrite and the banded mixed bainite and pearlite, by the existence of inclusions parallel and along with the bands, 34 bainite and martensite/austenite (M/A) interface, 40,41 as well as by the presence of higher dislocations volume fraction in the microstructural components of the fusion zone 42 . Few studies were dedicated to the effects of hydrogen on the mechanical properties of FSW welded joints of pipeline steels 2,14,32,43 .…”

Section: Introductionmentioning

confidence: 99%

“…[37][38][39] Some microstructures are more susceptible to HE, such as coarse microstructures, 2,40,41 the interface between the ferrite and the banded mixed bainite and pearlite, by the existence of inclusions parallel and along with the bands, 34 bainite and martensite/austenite (M/A) interface, 40,41 as well as by the presence of higher dislocations volume fraction in the microstructural components of the fusion zone. 42 Few studies were dedicated to the effects of hydrogen on the mechanical properties of FSW welded joints of pipeline steels. 2,14,32,43 In the API 5L X80, highstrength pipeline steel welded by friction-stir welding, the stir zone (SZ) showed less ductility than the base metal (BM), indicating the improved resistance to HE of the FSW.…”

Section: Introductionmentioning

confidence: 99%

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The effect of hydrogen on the fracture toughness of friction‐stir welded API 5L X70 pipeline steels

Giarola

Ávila

Cintho

et al. 2022

Fatigue Fract Eng Mat Struct

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The hydrogen embrittlement (HE) leads to severe steel degradation of mechanical properties. The hydrogen atoms diffuse into the steel and get positioned into reversible and irreversible trap sites. The pipe to transport oil and gas needs to be welded to construct long‐distance pipeline projects; thus, friction‐stir welding (FSW) has proven an excellent alternative to joining these pipelines. Therefore, this work assessed and analyzed the influence of hydrogen on the microstructure and fracture toughness of API 5L X70 steel welded by friction‐stir welding. The in‐service conditions were simulated by charging the specimen electrolytically in a 3.5% NaCl water solution with an intensity current of 2 mA·cm−2. According to fracture toughness tests, the base metal (BM) was more affected by hydrogen embrittlement than the friction‐stir zone (SZ), with a fracture toughness reduction of 20% after hydrogen charging. The SZ fracture toughness did not statistically show changes in hydrogen charging by the used times; however, the fracture mechanism changed from ductile to brittle‐like after 4 days of charging. The SZ depicted a better fracture toughness than BM due to the bainitic microstructure, a significant amount of irreversible hydrogen trapping.

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“…Therefore, the hydrogen changed the fracture type from ductile to quasi‐cleavage. These results are in accordance with the results reported by other researchers 35,42,77,79,95,98 …”

Section: Resultssupporting

confidence: 94%

Section: Resultsmentioning

confidence: 98%