Research on the hydrogen assisted fatigue damage in X80 pipeline steel welded joint

Zhao, Xiaohui; Wang, Hao; Liu, Gen; Liu, Yu; Xu, Desheng

doi:10.1016/j.mtcomm.2022.103524

Cited by 4 publications

(2 citation statements)

References 34 publications

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“…The KAM map of the scanned field view is shown in Figure 7(d). The average KAM value was counted 0.53°, a very small value [22,23]. Larger KAM value means higher geometrically necessary dislocation and more severe strain concentration.…”

Section: Resultsmentioning

confidence: 99%

Improvements in welding continuous cooling transformation diagram of high-strength low-alloy steel weld

Lai

Lei

Zhang

et al. 2023

Materials Science and Technology

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The welding continuous cooling transformation (CCT) diagram concerning microstructure evolution in a fine zone of the weld joint provides essential data for microstructure control in practice. In this study, a welding CCT diagram was improved to be elaborate by using the expanded lever rule. Processes for obtaining pieces of phase information are explained in detail. Improvements are: (i) phase areas are clearly presented, (ii) phase volume percentages are given, and (iii) overlapped phase areas are revealed. To meet high-strength requirement, a heat input of 21 kJ cm−1 was referenced from the welding CCT diagram, for achieving acicular ferrite and lath-like martensite. Transformed phase volume fractions are estimated and high strength and good toughness are obtained due to the elaborate phase information.

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Section: Resultsmentioning

confidence: 99%

Improvements in welding continuous cooling transformation diagram of high-strength low-alloy steel weld

Lai

Lei

Zhang

et al. 2023

Materials Science and Technology

View full text Add to dashboard Cite

show abstract

“…Natural gas pipelines in service are under alternating stress induced by internal pressure fluctuations and external load changes. As the service time increases, fatigue cracks initiate and even fatigue fractures occur in pipelines under alternating stress [ 16 ]. Among fracture modes of engineering structures, fatigue fractures account for a large proportion, particularly in natural gas pipelines under alternating stress, for which fatigue fractures account for more than 60% of total fracture modes.…”

Section: Introductionmentioning

confidence: 99%

Microstructures and Fatigue Properties of High-Strength Low-Alloy Steel Prepared through Submerged-Arc Additive Manufacturing

Chi

et al. 2022

Materials

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Submerged arc additive manufacturing (SAAM) is a viable technique for manufacturing large and complex specialized parts used in structural applications. At present, manufacturing high-strength low-alloy steel T-branch pipe through SAAM has not been reported. This paper uses this technology to manufacture low-alloy structural steel parts. The microstructures of the samples were characterized, which revealed that they were mainly composed of polygonal ferrites. The tensile properties in the horizontal and vertical directions of deposits were studied. Results show that the horizontal tensile strength of deposits was quite close to the vertical one, while the elongation rate in the vertical direction was obviously lower than that in the horizontal direction. Fatigue results indicate that the strain fatigue limit of high-strength low-alloy steel samples in vertical direction was 0.24%. The fatigue fractures of fatigue samples of deposits showed multi-source crack initiation characteristics and the crack propagation regions exhibited typical fatigue striations, so the final instantaneous fracture region showed a ductile fracture. Fatigue performance is very important for the safe service of structural parts, but there is a lack of relevant research on this additive manufacturing part. The results of this paper may support the popularization of the SAAM for high-strength low-alloy steel T-branch pipe.

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Effect of Heat Input on Microstructure and Corrosion Resistance of X80 Laser Welded Joints

Zhao

Wang

et al. 2022

Metals

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Using fiber laser welding technology, X80 pipeline steel welded joints with different welding heat inputs were obtained. Their microstructure, mechanical properties, and corrosion resistance (in NACEA solution saturated with hydrogen sulfide) were studied. Findings indicated that with the increase in heat input, the proportion of ferrite, strength, elongation, and corrosion resistance increased within a certain range and the sum of the proportion of martensite and bainite and hardness decreased. The heat input has a greater effect on the microstructure of weld metal (WM) and coarse-grained heat-affected zone (CGHAZ), while that of fine-grained heat-affected zone (FGHAZ) is basically unchanged. Obvious differences are also found in the corrosion resistance of different regions of the welded joints, among which FGHAZ has the strongest corrosion resistance, followed by WM and CGHAZ. The heat input mainly affects the microstructure type of the welded joint to affect the corrosion resistance. Therefore, we model the heat input as a function of Rct and icorr from this relationship. In addition, the corrosion products film produced by the long-term immersion of the welded joint in the saturated H2S NACEA solution can hinder the development of corrosion and enhance the corrosion resistance to a certain extent.

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Research on the hydrogen assisted fatigue damage in X80 pipeline steel welded joint

Cited by 4 publications

References 34 publications

Improvements in welding continuous cooling transformation diagram of high-strength low-alloy steel weld

Improvements in welding continuous cooling transformation diagram of high-strength low-alloy steel weld

Microstructures and Fatigue Properties of High-Strength Low-Alloy Steel Prepared through Submerged-Arc Additive Manufacturing

Effect of Heat Input on Microstructure and Corrosion Resistance of X80 Laser Welded Joints

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