Non-metallic inclusions in steels – origin and control

Silva, André Luiz Vasconcellos da Costa e

doi:10.1016/j.jmrt.2018.04.003

Cited by 138 publications

(56 citation statements)

References 111 publications

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“…3,8,15 Pipelines can suffer localized or generalized attack, depending on carbon steel, oil and operating conditions such as pressure, temperature and fluid dynamics. Localized corrosion arises from the existence of galvanic pairs formed between the predominant phase (e.g., ferritic phase) and the nonmetallic (e.g., MnS) or intermetallic (e.g., Fe 3 C) inclusions, 16 and it commonly manifests as pitting or mesa attack. 17,18 Generalized corrosion is a consequence of preferential dissolution of the predominant phase and it can be manifested by the formation of a mixed scale consisting principally of iron carbonate and cementite.…”

Section: Introductionmentioning

confidence: 99%

Films Formed on Carbon Steel in Sweet Environments - A Review

Fioravante¹,

Nunes²,

Acciari³

et al. 2019

J. Braz. Chem. Soc.

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Corrosion of carbon steel pipelines in sweet environments has been extensively researched on oil and natural gas exploration and production in order to obtain efficient corrosion mitigation methods. Although the consequences of corrosion are known, the cause and mechanism by which a certain phenomenon occurs are still not well understood. Sweet corrosion is mainly caused by the carbon dioxide dissolved in the water contained in the oil. It can manifest itself in different ways and one of which is the formation of a scale on the inner walls of the pipelines, which determines the evolution of corrosion process. This paper discusses the effects of partial pressure of carbon dioxide, dissolved hydrogen sulfide, dissolved oxygen and water chemistry on scale formation. Particular attention is paid to the nature and stability of the aqueous species formed during the corrosion process, as well as the thermodynamic and kinetic aspects lead to the scale formation on the carbon steel surface. The main objective is to enhance the understanding of the conditions of formation and precipitation of siderite and mackinawite and their effects on corrosion processes involving low carbon steels.

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Section: Introductionmentioning

confidence: 99%

Films Formed on Carbon Steel in Sweet Environments - A Review

Fioravante¹,

Nunes²,

Acciari³

et al. 2019

J. Braz. Chem. Soc.

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“…Although there are still some doubts concerning thermodynamic data for Al (9), Ca and Mg (10), in special, the present knowledge is sufficiently good to perform good predictions in the range of commercial steels. It is generally agreed that the deoxidations reactions involving Al and Si are not limited by nucleation and that the oxygen in solution in steels approaches the equilibrium values with the dissolved deoxidants very rapidly (11), at least when the pure oxide is formed. If, however, equilibrium must be attained with an oxide that is not pure, but dissolved in the slag, kinetics may play an important role (e.g.…”

Section: Deoxidation Thermodynamics and Kineticsmentioning

confidence: 99%

“…(12)(13)(14)(15)). While ladle stirring is critical for the kinetics of the metal-slag reactions, it is well established that judicious control must be exercised to avoid reoxidation and slag entrainment (11,16). For steel processed in LF under ideal conditions of agitation and with due care to prevent reoxidation, it has been observed that the final composition is very close to equilibrium (e.g.…”

Section: Deoxidation Thermodynamics and Kineticsmentioning

confidence: 99%

“…In this case, the equilibrium of all possible oxidation reactions should prevail and a single value of oxygen in solution should satisfy all the calculated equilibria, as indicated in Figure 1. If processing time is short, agitation is inadequate (either too weak or too strong (11)) and if reoxidation is not properly controlled, this condition, however, is not fulfilled. In this case, the observed values of the chemical composition of the steel and of the slag will indicate how the process is evolving.…”

Section: Deoxidation Thermodynamics and Kineticsmentioning

confidence: 99%

“…Furthermore, times as long as 30-40 minutes were used in some Al-deoxidized heats, which should approach equilibrium based on information acquired elsewhere in similar conditions, but under vacuum (e.g. (11)). This seems to indicate that the reduction of less stable oxides is not effective in the process and/or reoxidation by air is playing a relevant role in the process.…”

Section: Summary Of the Observationsmentioning

confidence: 99%

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Avaliação Do Equilibrio Metal-Escória Em Metalurgia Secundária

Silva¹,

Silva²,

Leitão³

et al. 2018

ABM Proceedings

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Resumo Steel-slag reactions are of paramount importance in steelmaking, in special in secondary steelmaking. Currently, desulfurization, deoxidation and inclusion removal are mostly performed during ladle processing. The extent to which these reactions proceed is governed by the initial state of the material reaching the ladle, the additions made to the ladle and by undesired interactions such as reoxidation and steelrefractory reactions. In this work fundamental thermodynamic aspects involved in ladle refining of Al-killed and Si-Mn deoxidized steel are briefly reviewed. Using thermodynamics, the extent to which equilibrium is approached for the different deoxidation reactions is evaluated. These results are compared to measurements performed in industrial ladle furnaces. Based on this comparison, observations are made with respect of the efficiency of the refining process. It is concluded that the relationship between agitation and reoxidation by air play a key role on the ability to reach low and controlled oxygen in steel. It is also concluded that relatively long treatments with controlled agitation are needed to achieve steel-slag equilibrium..

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Effect of Filter Functional Coating on Detrimental Nonmetallic Inclusions in 42CrMo4 Steel and Its Resulting Mechanical Properties

et al. 2019

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Carbon‐bonded ceramic foam filters with different functional coatings are immersed in a 42CrMo4 steel melt within a steel casting simulator. The solidified steel is analyzed with respect to the size distribution and the chemical composition of the remaining nonmetallic inclusions (NMI). Cyclic loading and quasi‐static tests are performed to determine the fatigue limit, the strength, deformability, and toughness of the steel after filter immersion. The immersion of filter with calcium hexaluminate (CA6) coating significantly reduces the population of small (4–20 μm) NMIs. This leads to an increased deformability and, thus, ability for energy dissipation during deformation. However, the maximum size of NMIs is increased from 100 to 150 μm, which results in fatigue limit reduction, despite the decrease in NMIs total density. The majority of inclusions are found to be pure alumina. Large (up to 150 μm) plate‐like alumina inclusions introduce most of the detrimental effects on cyclic strength, whereas significant effect on quasi‐static strength is not found.

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Non-metallic inclusions in steels – origin and control

Cited by 138 publications

References 111 publications

Films Formed on Carbon Steel in Sweet Environments - A Review

Films Formed on Carbon Steel in Sweet Environments - A Review

Avaliação Do Equilibrio Metal-Escória Em Metalurgia Secundária

Effect of Filter Functional Coating on Detrimental Nonmetallic Inclusions in 42CrMo4 Steel and Its Resulting Mechanical Properties

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