Shielded metal arc welding of 9%Ni steel using matching ferritic filler metal

El-Batahgy, Abdel-Monem; Saiyah, A.; Khafagi, S.; Gumenyuk, Andrey; Gook, Sergej; Rethmeier, Michael

doi:10.1080/13621718.2020.1846936

Cited by 15 publications

(7 citation statements)

References 16 publications

(19 reference statements)

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“…As a result, 200 °C was considered to be the optimum preheating temperature since it also has a positive effect on the manufacturing cost. It is also important to highlight that PWHT resulted in a hardness profile close to that of the optimum preheated joint and similar to that of previously published research on SMAW with 9%Ni steel [ 28 ]. This is due to a tempered martensitic structure with a more stable retained austenite.…”

Section: Resultssupporting

confidence: 83%

“…PWHT was performed at a temperature of 580 °C (1076 °F). The holding time was 20 min [ 28 ]. The cooling down of samples was conducted in an ambient atmosphere.…”

Section: Methodsmentioning

confidence: 99%

“…Matching filler metals for submerged arc welding (SAW) and gas tungsten arc welding (GTAW) have already been used in the fabrication of 9%Ni steel tubes [ 26 ] and in the construction of a laboratory-scale spherical model tank [ 27 ]. Recently, research on matching ferritic welding electrodes for shielded metal arc welding (SMAW) have shown attractive results, with an acceptable combination of tensile strength and impact toughness obtained [ 28 ]. Nevertheless, these filler metals are not yet extensively used for in-field welding, and more studies are still required in this important area, especially for the commonly used GMA welding process.…”

Section: Introductionmentioning

confidence: 99%

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Retaining Mechanical Properties of GMA-Welded Joints of 9%Ni Steel Using Experimentally Produced Matching Ferritic Filler Metal

et al. 2022

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Motivated by the loss of tensile strength in 9%Ni steel arc-welded joints performed using commercially available Ni-based austenitic filler metals, the viability of retaining tensile strength using an experimentally produced matching ferritic filler metal was confirmed. Compared to the austenitic Ni-based filler metal (685 MPa), higher tensile strength in gas metal arc (GMA) welded joints was achieved using a ferritic filler metal (749 MPa) due to its microstructure being similar to the base metal (645 MPa). The microstructure of hard martensite resulted in an impact energy of 71 J (−196 °C), which was two times higher than the specified minimum value of ≥34 J. The tensile and impact strength of the welded joint is affected not only by its microstructure, but also by the degree of its mechanical mismatch depending on the type of filler metal. Welds with a harder microstructure and less mechanical mismatch are important for achieving an adequate combination of tensile strength and notched impact strength. This is achievable with the cost-effective ferritic filler metal. A more desirable combination of mechanical properties is guaranteed by applying low preheating temperature (200 °C), which is a more practicable and economical solution compared to the high post-weld heat treatment (PWHT) temperature (580 °C) suggested by other research.

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Section: Resultssupporting

confidence: 83%

“…PWHT was performed at a temperature of 580 °C (1076 °F). The holding time was 20 min [ 28 ]. The cooling down of samples was conducted in an ambient atmosphere.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Retaining Mechanical Properties of GMA-Welded Joints of 9%Ni Steel Using Experimentally Produced Matching Ferritic Filler Metal

et al. 2022

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“…Improvements in properties and the study of crack behavior of dynamically loaded materials and weld joints in a variety of steel types has attracted the attention of numerous authors [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. In previous research [ 16 ] on martensitic steel P91, it was found that in the as-welded condition, the IC HAZ (intercritical HAZ) exhibited significantly higher impact toughness than the FG HAZ (fine-grained HAZ), while in the CG HAZ (coarse-grained HAZ), it was the lowest.…”

Section: Introductionmentioning

confidence: 99%

Simulation and Mechanical Properties of Fine-Grained Heat-Affected Zone Microstructure in 18CrNiMo7-6 Steel

et al. 2022

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Heat-affected zones (HAZs) in real welds are usually quite narrow, and consequently most standard mechanical tests are difficult or even impossible. Therefore, simulated microstructures are often used for mechanical tests. However, the most often used weld thermal cycle simulator produces only a few millimeters wide area of simulated microstructure in the middle of specimens. Consequently, these kind of simulated specimen are not suitable for standard tensile tests, and even for Charpy impact tests, the simulated area can be too narrow. Therefore, to investigate the mechanical properties of a fine-grain heat-affected zone in 18CrNiMo7-6 steel, two methods were used for simulation of as-welded microstructures: (a) a weld thermal cycle simulator, and (b) as an alternative, though not yet verified option, austenitizing in a laboratory furnace + water quenching. The microstructures were compared and mechanical properties investigated. The grain sizes of the simulated specimens were 10.9 μm (water-quenched) and 12.6 μm (simulator), whereby the deviations from the real weld were less than 10%. Both types of simulated specimen were used for hardness measurement, Charpy impact tests, and fatigue tests. Water-quenched specimens were large enough to enable standard tensile testing. A hardness of 425 HV, yield strength Rp02 = 1121 MPa, tensile strength Rm = 1475 MPa, impact energy KV = 73.11 J, and crack propagation threshold ΔKthR = 4.33 MPa m0.5 were obtained with the water quenched specimens, and 419 HV, KV = 101.49 J, and ΔKthR = 3.4 MPa m0.5 with the specimens prepared with the simulator. Comparison of the results confirmed that the annealed and quenched specimens were suitable for mechanical tests of FG HAZs, even for standard tensile tests. Due to the use of simulated test specimens, the mechanical properties determined can be linked to the FG HAZ microstructure in 18CrNiMo7-6 steel.

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“…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.…”

mentioning

confidence: 99%

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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Shielded metal arc welding of 9%Ni steel using matching ferritic filler metal

Cited by 15 publications

References 16 publications

Retaining Mechanical Properties of GMA-Welded Joints of 9%Ni Steel Using Experimentally Produced Matching Ferritic Filler Metal

Retaining Mechanical Properties of GMA-Welded Joints of 9%Ni Steel Using Experimentally Produced Matching Ferritic Filler Metal

Simulation and Mechanical Properties of Fine-Grained Heat-Affected Zone Microstructure in 18CrNiMo7-6 Steel

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

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