Computational Thermodynamic Study of Inclusions Formation in the Continuous Casting of SAE 8620 Steel

Bielefeldt, Wagner Viana; Vilela, Antônio Cezar Faria

doi:10.1002/srin.201000057

Cited by 9 publications

(6 citation statements)

References 14 publications

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“…Controlar a distribuição de tamanho, morfologia, e composição das inclusões não-metálicas é um dos fatores mais importantes para não comprometer as etapas de processamento subsequentes, bem como as propriedades e a qualidade do produto final [4][5][6]. Na produção de aços especiais (especialmente para a indústria automotiva) os requisitos de qualidade estão acima da média, se comparados aos dos aços comerciais comuns [7]. Além disso, tais aços são considerados críticos em relação a sua produção, já que a quantidade de alguns de seus elementos, tais como, Al, S, Ca e O, deve ser controlada.…”

Section: Introductionunclassified

Estudo De Inclusões Não-Metálicas Em Aços Durante Tratamento Em Desgaseificador a Vácuo E Início Do Lingotamento Contínuo

Bartosiaki¹,

Pereira²,

Bielefeldt³

et al. 2014

ABM Proceedings

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ResumoO atingimento de limpeza inclusionária está ligado ao entendimento de como cada etapa de processamento de aços influenciam no comportamento inclusionário. Neste estudo, retiraram-se amostras de aço antes e após o tratamento a vácuo e no distribuidor do lingotamento contínuo em uma planta siderúrgica. As amostras foram submetidas à análise via MEV/EDS automatizado e a medições de oxigênio total. O posicionamento da composição química das inclusões varridas em diagramas ternários remetidas à análise de suas morfologias, bem como a correlação do nível inclusionário com parâmetros de processo e de escórias, possibilitou o entendimento de como as inclusões se comportam. A forte agitação promovida pelo desgaseificador aumenta as interações entre banho, escória e inclusões, de modo que o conteúdo de CaO e de SiO 2 nas inclusões aumenta. A transferência de elementos da escória para as inclusões por intermédio do banho é acentuado, fato observado pela geração de espinélios (MgO.Al 2 O 3 ) ao final do processo. De modo geral, observou-se que além do efeito do abaixamento da temperatura na geração de novas inclusões, o fator reoxidação deve ser levado em conta. Em contrapartida, há a diminuição nos níveis de inclusões maiores desde o início do tratamento em vácuo até o distribuidor. O objetivo deste estudo foi verificar como ocorre a remoção, tratamento e modificação das inclusões nas etapas finais de processamento em aciaria. Palavras-chave: Caracterização de inclusões; Escórias; Composição química; Modificação de inclusões.

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Section: Introductionunclassified

Estudo De Inclusões Não-Metálicas Em Aços Durante Tratamento Em Desgaseificador a Vácuo E Início Do Lingotamento Contínuo

Bartosiaki¹,

Pereira²,

Bielefeldt³

et al. 2014

ABM Proceedings

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“…This methodology has been used by Bielefeldt W. and Vilela A.C.F. ; Lino et al with great success 59,60 . Figure 10 shows the calculated stability diagram used to study the formation of MgO/MgO , which may explain the appearance of these inclusions in the steel.…”

Section: Inclusion Characterizationmentioning

confidence: 99%

Analysis of Spinel Based Inclusions During the Last Stage of The Steelmaking Process of SAE 52100

et al. 2020

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Al 2 O 3 (alumina) and MgO•Al 2 O 3 (spinel) inclusions cause valve obstruction (clogging) in continuous casting and can deteriorate the quality of the final product. In this context, industrial heats of the bearing steel SAE 52100 was examined. Samples were collected in the final steps of the steelmaking process, both after vacuum treatment and during continuous casting. A scanning electron microscope (SEM) equipped with a energy-dispersive spectrometer (EDS) and automated particle characterization analysis was used to characterize the inclusions present in the steel samples. Thermodynamic calculations were performed with the commercial software FactSage TM 7.2. Based on thermodynamic predictions, parameters such as solid fraction, liquid fraction, MgO saturation point of the slags, content of dissolved elements in steel (Al, Mg, Ca,...) and the construction of a phase stability diagram were determined. The results in this study showed a tendency for increase in MgO content in the inclusions with the decrease of %FeO and SiO 2 contents in the slag, an increase of binary basicity (%CaO/%SiO 2). It is verified that the MgO contents in the slag were close to the saturation, increasing the probability for the formation of inclusions rich in MgO and/or spinel. On the other hand, stability diagrams confirm the formation of spinel inclusions for each of the heats analyzed. During the final step of the steelmaking process, there is a tendency for re-oxidation, which is verified by an increase in the density of inclusions (or total oxygen TO values).

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“…Many scholars have conducted research on the control and removal of inclusions in terms of their compositions and sizes [9], such as the use of calcium treatment to modify inclusions [10][11][12][13]. However, the insufficient or excessive addition of calcium can result in high-melting-point inclusions, such as partially modified Al 2 O 3 or spinel inclusions, as well as CaS, which worsens the treatment effect [14][15][16][17][18]. Many scholars [19][20][21] used aluminum deoxidation slag and refining slag with a high desulfurization capacity to remove sulfur from steel.…”

Section: Introductionmentioning

confidence: 99%

Effect of Al2O3 on Inclusion Removal in H13 Steels Using High-Basicity LF (Ladle Furnace) Refining Slags

Liang,

Qin,

Wang

2023

Metals

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In this experiment, a quaternary fluorine-free refining slag system of CaO-SiO2-Al2O3-MgO was selected, with basicity ratios of 2, 4, and 6 and calcium-aluminum ratios of 1.5, 2.1, and 3. High-temperature “slag-steel equilibrium” experiments were conducted to investigate the influence of different basicity ratios and calcium–aluminum ratios on the morphologies, compositions, sizes, and quantities of the inclusions in H13 steel, aiming to improve the cleanliness of H13 steel to meet practical industrial requirements. The experimental results showed that with the increase in the basicity ratio and the calcium–aluminum ratio, the morphologies of the inclusions changed from elliptical to regular circular, with more regular edges. As the basicity ratio increased from 2 to 6, the densities of the inclusions showed a decreasing trend, with values of 40, 35, 30, 25, 32, and 30 inclusions/mm2. When the basicity ratio remained the same, the average size of the inclusions in the steel decreased first and then increased with the increases in the calcium–aluminum ratios, with sizes of 1.59 μm, 1.23 μm, and 1.38 μm, respectively. Among these, when the basicity ratio was 6 and the calcium–aluminum ratio was 2.1, the control effect on the densities and sizes of the inclusions was the best, yielding an inclusion density of 25 inclusions/mm2 and a size of 1.15 μm. Additionally, reducing the Al2O3 content in the slag could reduce the Al2O3 contents in the inclusions, which also promoted improvements in the elastic deformation capacities of the inclusions. With increases in the calcium–aluminum ratios in the slag system, the masses of the inclusions decreased due to the reduced Al contents in the steel. The Al contents in the steel also had an impact on the compositions of the inclusions.

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Computational Thermodynamic Study of Inclusions Formation in the Continuous Casting of SAE 8620 Steel

Cited by 9 publications

References 14 publications

Estudo De Inclusões Não-Metálicas Em Aços Durante Tratamento Em Desgaseificador a Vácuo E Início Do Lingotamento Contínuo

Estudo De Inclusões Não-Metálicas Em Aços Durante Tratamento Em Desgaseificador a Vácuo E Início Do Lingotamento Contínuo

Analysis of Spinel Based Inclusions During the Last Stage of The Steelmaking Process of SAE 52100

Effect of Al2O3 on Inclusion Removal in H13 Steels Using High-Basicity LF (Ladle Furnace) Refining Slags

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