Effect of Hot‐Bending Process on Microstructure and Mechanical Property of K65 Submerged ARC Welded Pipe

Dong, Liming; Pan, Xin; Wang, Yinbai

doi:10.1002/9781119027973.ch88

Cited by 3 publications

(6 citation statements)

References 6 publications

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“…Mingwei Tong et al [8] also found deteriorating impact toughness of fire-resistant construction steel with increasing Mo content. However, the conclusion reached by Hardy et al [7,14] was just the opposite. They observed [14] simultaneous improvement of the strength and low-temperature toughness of MoNb-based low-carbon bainitic steel, with an increase in Mo content due to grain refinement.…”

Section: Introductionmentioning

confidence: 89%

“…A large number of studies have shown that grain size [8,14,25], M/A constituents [2,6,12,15,19,20], and microstructure composition [7,11] significantly affect the low-temperature toughness of this kind of low-carbon micro-alloyed steel. In particular, the impact toughness is significantly affected by the size, content, and shape of the hard-phase M/A constituents [2,6,12,15,19,20].…”

Section: Effect Of Mo Content On the Impact Toughnessmentioning

confidence: 99%

“…They observed [14] simultaneous improvement of the strength and low-temperature toughness of MoNb-based low-carbon bainitic steel, with an increase in Mo content due to grain refinement. Liming Dong et al [7] also found that for the weld seam of K65 hot bent pipe, the proportion of high-angle grain boundaries in the microstructure increased by 67.1%, and the toughness at −40 • C also increased to 124 J due to an increase in Mo content by 0.20%. Therefore, the influence of Mo on low-temperature toughness is controversial.…”

Section: Introductionmentioning

confidence: 95%

“…However, higher constraints have been imposed on the wall thickness and low-temperature toughness (≤−45 • C) of X80-grade pipeline steel [1][2][3][4] in order to meet the increasing demands of long-distance transmission in extremely cold regions and high flow rates of natural gas. X80-grade steel is designed with lower carbon content [5][6][7][8][9] in order to achieve excellent weldability. Thus, in order to strengthen the matrix, refine the microstructure, and meet the high-strength requirements, it is necessary to add the elements Mo and Ni.…”

Section: Introductionmentioning

confidence: 99%

“…Low carbon bainite is the typical structure of X80-grade pipeline steel. In this kind of microstructure, the phase ratio [7,11,13] and grain size [8,9,14], especially the characteristics of the hard-phase M/A constituents [2,3,12,15,16], have a significant effect on the low-temperature toughness.…”

Section: Introductionmentioning

confidence: 99%

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Insight into the Role of Mo Content on the Microstructure and Impact Toughness of X80 Thick-Walled Low-Temperature Pipeline Steel

Jiang,

Zhang,

Zhao

et al. 2023

Metals

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In this manuscript, the effects of Mo content on the microstructure and impact toughness of X80 thick-walled low-temperature pipeline steel were studied. Two test steels with different Mo content (0.25% and 0.40%) were prepared by the thermo-mechanical control process. The impact properties were measured at −45 °C, and the microstructure evolution was observed via an optical microscope (OM), a scanning electron microscope (SEM), electron back-scattered diffraction (EBSD), and a transmission electron microscope (TEM). Each steel showed the formation of a mixed microstructure consisting of polygonal ferrite (PF), granular bainite (GB), and lath bainite (LB). Increasing Mo content resulted in the rise of LB at the expense of PF and GB. At the same time, the morphology of martensite/austenite (M/A) constituents changed from blocky to slender. The dislocation density in the ferrite matrix around the M/A constituents enhanced with an increase in Mo content. This also led to an increase in the microstrains around the M/A constituents. Also, the number fraction of the high angle grain boundary (HAGB) (MTA > 15°) decreased with the addition of more Mo content. Furthermore, with an increase in Mo content from 0.25% to 0.40%, the low-temperature impact toughness decreased from 206 to 57 J. Both an increase in the slender M/A constituents and a decrease in the HAGB number fraction deteriorated the low-temperature impact toughness of the X80 thick-walled low-temperature pipeline steel.

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Section: Introductionmentioning

confidence: 89%

Section: Effect Of Mo Content On the Impact Toughnessmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Insight into the Role of Mo Content on the Microstructure and Impact Toughness of X80 Thick-Walled Low-Temperature Pipeline Steel

Jiang,

Zhang,

Zhao

et al. 2023

Metals

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Investigation of the microstructure and toughness of 550 MPa grade pipeline after the hot-bending process

Wang

Tsai

Yang

et al. 2016

Materials Science and Technology

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In this work, the effects of the hot-bending process on the microstructure and low temperature (−40°C) toughness of weld metal of pipeline K65 (the highest grade of the Russian natural gas pipeline) were studied. The weld metal from the longitudinally submerged arc welding (LSAW) pipe making process was compared with that subsequently treated by the hot-bending process. It was found that the latter process led to serious deterioration in toughness, which obviously degraded the sound properties achieved in the original weld metal of LSAW pipes. Microstructural characterisation revealed that the weld metal, which originally consisted mainly of acicular ferrite in the as-deposited condition, became predominantly composed of bainitic ferrite after hot bending. It is clear that reaustenisation caused a smaller austenite grain-sized matrix, which brought about a very high volume fraction of bainite. Consequently, the low temperature toughness was deteriorated, in contrast to the excellent toughness achieved in the as-deposited weld metal.

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Transfer Welding Process and Microstructure and Properties of Titanium/Steel Clad Pipe

Bi¹,

Yang²

2018

MSF

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Titanium/steel clad material with excellent mechanical properties and corrosion resistance has important application in the oil, gas and ocean equipment. Due to the metallurgical incompatibility of titanium and steel, the mechanical properties of weld joint would completely lose when the brittle intermetallic phase existed in the fusion welding process. Therefore, the gas tungsten arced welding (TIG) + metal inert-gas welding (MIG) + metal active-gas welding (MAG) with pure vanadium and pure copper composite filler metals for welding connection experiment in this study was carried out on Ø610mm×(14+2)mm TA1/X65 titanium/steel clad pipe fitting (titanium cladding with thickness 2 mm, X65 pipeline steel with thickness 14 mm). The microstructure, interface element distribution, main phase, microhardness distribution on cross section and mechanical properties of butt welds were researched by using OM, XRD, EDS element mapping, microhardness and tensile tests. The result showed that the use of pure vanadium and pure copper composite filler metals for welding connection could effectively avoid the production of intermetallic compounds in the process of titanium/steel composite pipe fusion welding. The deposited metal of titanium, vanadium, copper and steel had obvious zoning, the inter-diffusion melting phenomenon was not severe, which is by using solid solution phases to transit zonings of deposited metal. The microstructure of titanium and vanadium transition interface were composed of titanium-based solid solution, the microstructure of vanadium and copper transition interface was composed of vanadium-based solid solution, and the microstructure of copper and steel transition interface were composed of copper-based solid solution. The transition interface had no porosity, crack and other defects. The tensile strength of the weld was 546MPa, which is mainly contributed by the carbon steel layer. With pure vanadium and pure copper as transition filler metal for the welding connection TA1/X65 clad pipe was successfully realized by TIG+MIG+MAG welding method, and the strength index reached the desired effect.

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Effect of Hot‐Bending Process on Microstructure and Mechanical Property of K65 Submerged ARC Welded Pipe

Cited by 3 publications

References 6 publications

Insight into the Role of Mo Content on the Microstructure and Impact Toughness of X80 Thick-Walled Low-Temperature Pipeline Steel

Insight into the Role of Mo Content on the Microstructure and Impact Toughness of X80 Thick-Walled Low-Temperature Pipeline Steel

Investigation of the microstructure and toughness of 550 MPa grade pipeline after the hot-bending process

Transfer Welding Process and Microstructure and Properties of Titanium/Steel Clad Pipe

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