Improvement of cryogenic toughness for 9% Ni steel keyhole TIG butt-welded joints with a Ni interlayer

Xu, Tao; Jiang, Zexin; Wu, Leilei; Shi, Yonghua; Ma, Ying; Wang, Zishun

doi:10.1016/j.msea.2022.142661

Cited by 16 publications

(6 citation statements)

References 26 publications

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“…However, the WM of 9% Ni steel was designed to exhibit superior hardness in the range of 243–350 HV, compared to the BM. [ 9,11,12,14,28 ]…”

Section: Resultsmentioning

confidence: 99%

“…Table 4 compares the WM hardness of the weld joint of 9% Ni steel using various types of commercial filler materials and welding processes. [9,11,12,14,28] The hardness of the WM in the weld joint could differ depending on the chemical composition of the filler material, type of welding process, welding parameters, and cooling conditions. However, the WM of 9% Ni steel was designed to exhibit superior hardness in the range of 243-350 HV, compared to the BM.…”

Section: Mechanical Properties Of the Weld Jointmentioning

confidence: 99%

“…However, the WM of 9% Ni steel was designed to exhibit superior hardness in the range of 243-350 HV, compared to the BM. [9,11,12,14,28] Figure 10 shows the results of tensile tests conducted at 25 and À163 °C. A distinct welding boundary is observed between the 9% Ni steel and WM in the radiographic image.…”

Section: Mechanical Properties Of the Weld Jointmentioning

confidence: 99%

“…Consequently, major shipbuilders, who are responsible for the maintenance of most existing LNG tanker fleets, have started searching for inexpensive filler metals to meet their economic requirements. [14][15][16][17] Various alternatives have been studied to meet the rapidly increasing demand for cost-effective filler materials, and Fe-based alloys have emerged as the most efficient substitute for Ni-based alloys. In general, filler materials of Febased alloys form a ferrite phase in the WM and are therefore not suitable for use in welding 9% Ni steel.…”

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Fe‐Based Filler Material Forming Austenite‐Covered Packet Lath Martensite for Gas Tungsten Arc Welding of 9% Ni Steel

Choi,

Hwang,

Jung

2023

steel research int.

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An Fe‐based filler material with a composition of Fe‐20Ni‐5Co‐2.5Mn‐0.2C was developed for welding 9% Ni steel. To ensure high weldability through compositional similarity, the composition of the Fe‐based filler material was designed based on that of 9% Ni steel. The filler material had elements such as Ni, Mn, Co, and C to enhance its compatibility with the 9% Ni steel. The Fe‐based filler material was designed to control the martensite formation temperature, resulting in the appearance of the martensite‐austenite dual phase during rapid cooling. The weld joint which utilized the filler material showed a distinct microstructure characterized by the presence of austenite‐covered packet lath martensite. The mechanical properties of the weld joint were investigated via Vickers harness and tensile tests at 25 and −163 °C. In comparison to 9% Ni steel, the weld joint prepared using the Fe‐based filler material exhibited yield and tensile strengths that were ∽5.5% higher. Additionally, the tensile fracture of the specimen occurred exclusively within the base metal, without any involvement of the weld metal or heat‐affected zone. Further, the fracture surface was observed. The findings of this study demonstrate the applicability of the Fe‐based filler material for welding 9% Ni steel.This article is protected by copyright. All rights reserved.

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“…However, the WM of 9% Ni steel was designed to exhibit superior hardness in the range of 243–350 HV, compared to the BM. [ 9,11,12,14,28 ]…”

Section: Resultsmentioning

confidence: 99%

Section: Mechanical Properties Of the Weld Jointmentioning

confidence: 99%

Section: Mechanical Properties Of the Weld Jointmentioning

confidence: 99%

mentioning

confidence: 99%

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Fe‐Based Filler Material Forming Austenite‐Covered Packet Lath Martensite for Gas Tungsten Arc Welding of 9% Ni Steel

Choi,

Hwang,

Jung

2023

steel research int.

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“…The use of thin nickel foil strips in the joint can promote the austenite formation in the complete cross section of the HLAW weld [54]. In [55] a TIG welding process is described in which a 0.5 mm thick Ni interlayer is introduced into the groove to improve the cryogenic toughness of the 9% Ni welded joint. Another method to realize a homogeneous distribution of the filler metal in the weld seam for thick plates is a so-called "two-step process", in which the austenitic filler metal is applied to the edges of the weld partners by means of laser metal deposition (LMD) in the first step.…”

Section: Discussionmentioning

confidence: 99%

Application of Hybrid Laser Arc Welding for Construction of LNG Tanks Made of Thick Cryogenic 9% Ni Steel Plates

Gook,

El-Batahgy,

Gumenyuk

et al. 2023

Lasers Manuf. Mater. Process.

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Hybrid laser-arc welding (HLAW) was applied for butt welding of 14.5 mm thick plates of ferritic cryogenic steel X8Ni9 containing 9% Ni, which is used for manufacturing storage and transport facilities of liquefied natural gas (LNG). The weld seam formation and the achievable metallurgical and mechanical properties of the hybrid welds were investigated experimentally for two types of filler wire, an austenitic wire dissimilar to the base metal (BM) and an experimentally produced matching ferritic wire. Safe penetration and uniform distribution of the austenitic filler metal in the narrow hybrid weld could only be achieved in the upper, arc-dominated part of the weld. The pronounced heterogeneous distribution of the austenitic filler metal in the middle part and in the root area of the weld could not ensure sufficient notched impact toughness of the weld metal (WM). As a result, a decrease in the impact energy down to 17 ± 3 J was observed, which is below the acceptance level of ≥ 34 J for cryogenic applications. In contrast, the use of a matching ferritic filler wire resulted in satisfactory impact energy of the hybrid welds of up to 134 ± 52 J at the concerned cryogenic temperature of -196 °C. The obtained results contribute to an important and remarkable conversion in automated manufacturing of LNG facilities. In other words, the results will help to develop a new laser-based welding technology, where both quality and productivity are considered.The efficiency of the developed welding process has been demonstrated by manufacturing a prototype where a segment of the inner wall of large size LNG storage tank was constructed. In this concern, hybrid laser arc welding was conducted in both horizontal (2G) and vertical (3G) positions as a simulation to the actual onsite manufacturing. The prototype was fabricated twice where its quality was confirmed based on non-destructive and destructive examinations.

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Correlation between microstructure and mechanical properties of welding joint in 9% Ni steel with two types of Ni-based superalloy filler metals

Hwang

Choi²,

Jung³

2022

Int J Adv Manuf Technol

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Improvement of cryogenic toughness for 9% Ni steel keyhole TIG butt-welded joints with a Ni interlayer

Cited by 16 publications

References 26 publications

Fe‐Based Filler Material Forming Austenite‐Covered Packet Lath Martensite for Gas Tungsten Arc Welding of 9% Ni Steel

Fe‐Based Filler Material Forming Austenite‐Covered Packet Lath Martensite for Gas Tungsten Arc Welding of 9% Ni Steel

Application of Hybrid Laser Arc Welding for Construction of LNG Tanks Made of Thick Cryogenic 9% Ni Steel Plates

Correlation between microstructure and mechanical properties of welding joint in 9% Ni steel with two types of Ni-based superalloy filler metals

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