Development of technology for producing low‐hydrogen electrodes

Marchenko, A.E.; Pokhodnya, I. K.; Skorina, N.V.; Alekseev, Yu G; Kostyuchenko, V. P.; Gridin, A A

doi:10.1080/09507119509548753

Cited by 3 publications

(8 citation statements)

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“…Grain composition of coating materials significantly effects consistency and technological properties of electrode compounds. It is confirmed by results of investigation of viscosity of UONI-13/55 compound, published in [1,2]. It was evaluated as pressure loss in pumping of compound from feed cylinder of viscosimeter in round nozzle of 5 mm diameter and 50 mm length at constant consumption Q = 5 cm 3 ⋅s -1 (average gradient of shear rate 100 s -1 ).…”

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confidence: 68%

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Effect of charge grain composition on rheological characteristics and structure of pressure flow of compounds for low-hydrogen electrodes

Marchenko¹

2014

The Paton Welding J.

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It is determined in course of investigation of compound of low-hydrogen electrodes UONI-13/55, carried out with the help of capillary viscosimeter, that their rheological indices and structure under flow pressure condition significantly depend on grain composition of coating materials. Charge should contain 50 % of fine fraction from point of view of minimizing of energy consumption, necessary for extrusion application of compounds on rods. Deviation of its portion in one or another side from indicated optimum significantly rises energy consumption on electrode extrusion. The compounds with fine-or coarse-grain filler are not similar to each other on structure. It confirms nature of change of level of compound dissipative heating, value of natural convergence angle in entrance zone (to capillary) as well as shape of deformation (extrusion) curves at increase of flow velocity. Profile of flow of compounds with coarse-grain filler expands at rise of pressure jet rate. It remains virtually of the same narrow shape as at creep flow velocities for flow of compounds with fine-grain filler. The results of analysis of form of extrusion curves P = f(t) indicate that pressure flow of compound with coarse-grain filler is realized on viscosity mechanism. The compounds with excessive content of fine-grain filler are more structured, since liquid glass binder in these cases in addition to filling of intergrain voids should cover significantly more developed grain surface. Rise is observed in their molecular interaction and strength of structure formed by them, which is fractured in deformation and accompanied by specific phenomena of unsteady flow. 8 Ref., 2 Tables, 8 Figures. K e y w o r d s : low-hydrogen welding electrodes, coating thickness difference, rheology of compounds, viscosity and elasticity indices of compounds

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confidence: 68%

“…where Angle α 0 reduces with rise of flow velocity for those materials, where longitudinal viscosity decreases intensively than shear one. Convergent zone of such materials acquires watering-can shape [1,2,4,5].…”

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confidence: 99%

Effect of charge grain composition on rheological characteristics and structure of pressure flow of compounds for low-hydrogen electrodes

Marchenko¹

2014

The Paton Welding J.

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“…Известно, что состав покрытия существенно влияет на химический состав металла сварного шва, облегчая перенос элементов в сварные швы и тем самым добавляя легирующие элементы в зону сварного шва. На поведение сварочных покрытий влияют некоторые физико-химические и теплофизические характеристики компонентов электродного покрытия [6][7][8] Следует также отметить, что шлак темно-синего цвета имел тенденцию отслаиваться большими кусками от металла шва, а коричневые шлаки разбивались на мелкие кусочки при выбивании сварного валика и оставляли некоторое количество шлака, прилипшего к поверхности металла шва.…”

Section: обсуждение результатовunclassified

“…Присутствие водорода в зоне плавления при сварке сталей может быть опасным, поскольку вызывает образование холодных трещин как в зоне термического влияния, так и в зоне плавления, которые являются причиной катастрофического разрушения сварной стальной конструкции. Холодные трещины, вызванные водородом, представляют собой серьезную проблему свариваемости низколегированых высокопрочных сталей [2][3][4][5][6][7]. Холодные трещины возникают при одновременном существовании трех факторов: остаточных напряжений после сварки, хрупких структур в зоне термического влияния (ЗТВ) и высокого содержания диффузионного водорода в наплавленном металле [2].…”

Section: Introductionunclassified

“…Одним из механизмов диффузионного восстановления водорода является снижение парциального давления водорода в атмосфере сварочной дуги -например, за счет диссоциации карбонатов и фторидов, а именно Na 2 CO 3 , NaF, CaCO 3 , CaF 2 , MgCO 3 и MgF 2 . Карбонаты диссоциируют с образованием CO 2 и CO, что снижает парциальное давление водорода над сварочной ванной [5][6][7][8][9][10][11]. Разложение электродного покрытия основного типа, содержащего в качестве основного компонента (45-50 %) CaCO 3 , приводит к образованию газовой защиты с низким содержанием водорода.…”

Section: Introductionunclassified

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Assessment of welding engineering properties of basic type electrode coatings of different electrode manufacturers for welding of pipe parts and assemblies of heat exchange surfaces of boiler units

Karlina,

Kononenko,

Popov

et al. 2024

Metal Working and Material Science

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Introduction. New grades of high-strength steels, machining and repair processes are being introduced in the power industry. At the same time manual arc welding remains the main technological process for equipment repair in conditions of thermal power plants. Welding materials used in equipment repair should provide comparable to the base metal mechanical properties of the weld. The welding industry has long faced the problem of high sensitivity of basic type electrodes to moisture absorption. High susceptibility to cold cracking caused by diffusible hydrogen and hydrogen embrittlement are major obstacles to the wider use of basic-type electrodes for high-strength steels. Hydrogen production during arc welding is the result of the presence of hydrogen in the arc atmosphere, hydrogen-contaminated filler material, or local hydrogen residues on the source material. During welding, molecular hydrogen is dislocated by the arc energy and then easily absorbed by the molten material. Currently, the welding materials market produces electrodes with basic coating of well-known and proven brands, various national and foreign manufacturers. However, in practice there are cases of cold cracks in the weld seam after welding. Purpose of work is to assess the welding and technological properties of basic type electrode coatings of different manufacturers. The work investigates specimens weld overlaid with electrodes TMU-21U, TSU-5 of different manufacturers and the content of diffusion-mobile hydrogen in the weld overlaid metal is determined. The methods of research are mechanical static tensile tests, chemical composition analysis and metallographic studies. Determination of welding-induced hydrogen content can be accomplished by various quantitative elemental analysis methods. All test methods involve welding under defined conditions followed by deep freezing of the test specimens as quickly as possible. In this way, unintended diffusion processes are inhibited and the hydrogen introduced into the weld metal is retained. Subsequently, the diffusing hydrogen is desorbed from the test specimens in a controlled manner. Results and Discussion. An assessment of welding engineering properties of the electrodes revealed unstable arc burning. Mechanical properties of the welded metal of the investigated electrodes are at the minimum permissible level from the requirements of normative documents. The concentration of hydrogen present in the arc weld metal is multifactorially dependent on the welding procedure (process and parameters, consumables used, as well as environmental conditions (e.g. humidity). For qualitative assessment, hydrogen content of more than 15 cm3/100 g is considered high and hydrogen content less than 5 cm3 ml/100 g is considered very low. Presented results. The conducted evaluation of welding engineering properties of electrodes with basic coating showed satisfactory results. Mechanical properties of the welded metal in terms of impact toughness are at the lower permissible limit, relative elongation does not meet the requirements of normative documents. The content of diffusion-mobile hydrogen in the welded metal is higher than the declared indicators by the electrode manufacturers.

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Effect of martensite on cold cracking in 600-MPa grade flux-cored arc weld metals using the Y-groove test

et al. 2015

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Development of technology for producing low‐hydrogen electrodes

Cited by 3 publications

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Effect of charge grain composition on rheological characteristics and structure of pressure flow of compounds for low-hydrogen electrodes

Effect of charge grain composition on rheological characteristics and structure of pressure flow of compounds for low-hydrogen electrodes

Assessment of welding engineering properties of basic type electrode coatings of different electrode manufacturers for welding of pipe parts and assemblies of heat exchange surfaces of boiler units

Effect of martensite on cold cracking in 600-MPa grade flux-cored arc weld metals using the Y-groove test

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