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

Bartosiaki, Bruna Goulart; Pereira, Julio Aníbal Morales; Bielefeldt, Wagner Viana; Vilela, Antônio Cézar Faria

doi:10.5151/1982-9345-24250

Cited by 3 publications

(6 citation statements)

References 13 publications

(17 reference statements)

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“…In general, it is concluded that Al 2 O 3 inclusions are formed as a result of re-oxidation by air (the effect of the oxidation degree in slag is smaller) and the decrease in temperature during the final step of the steel manufacturing process 9,27,43 . On the other hand, the formation of inclusions of pure spinel (MgO⋅Al 2 O 3 ) is facilitated due to an increase in slag fluidity, which leads to increased MgO erosion of slag line refractories, as well as MgO saturation, which increase the dissolved magnesium in the liquid steel 1,9,10,17,18,[44][45][46][47][48] . Secondary spinel formation by re-oxidation after modification with calcium should also be considered 38,45,47,49,50 .…”

Section: Inclusionary Analysismentioning

confidence: 99%

“…The disintegration of the aluminate complexes into smaller units results in a decrease in viscosity. According to the studies of Asth 14 and Bartosiaki et al 17,18 , an excess of refractory oxides (CaO and MgO) can increase the viscosity of slags due to the presence of solids (CaO precipitation or CaO rich phases, spinels (MgO•Al 2 O 3 ) and MgO) which are detrimental to the process of nonmetallic inclusion removal. According to Valdez et al 7 , increasing the viscosity of the slag (by the effect of solid phase precipitation) causes a much longer time for the inclusions to be completely removed from liquid steel, and in the case of a low viscosity slag, the particle can be more easily removed through it.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of Secondary Refining Slag Parameters with Focus on Inclusion Cleanliness

et al. 2018

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Secondary refining slag samples with different chemical compositions (45-54 % CaO, 7-13 % Al 2 O 3 , 20-29 % SiO 2 , 9-16 % MgO, 0-5 % CaF 2) were investigated to verify the influence of their effective viscosity on inclusion cleanliness of DIN 38MnS6 in a steelmaking plant. The steel samples were collected during the production process for analysis of inclusions. Using the commercial software FactSage 6.4, thermodynamic calculations were performed to determine the effective viscosity, solid fraction, liquid fraction and MgO saturation point of these slags at 1560ºC. The results showed that all the slags were saturated in MgO, revealing a better protection of the ladle refractory. The addition of 2 to 5 % of CaF 2 reduced the effective viscosity values for the analyzed slags from 0.45 Pa•s to 0.10 Pa•s , in comparison to the slags without the addition of CaF 2 , with an effective viscosity of 0.40 Pa•s, 0.27 Pa•s and 0.22 Pa•s, decreasing the level of non-metallic inclusions for some of the analysed heats. However, it was detected during the manufacturing process that high slag fluidity and re-oxidation events continue to be a challenge associated with reducing the level of non-metallic inclusions.

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Section: Inclusionary Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of Secondary Refining Slag Parameters with Focus on Inclusion Cleanliness

et al. 2018

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“…The sampling methodology follows the experimental procedure adopted in previous studies [24][25][26][27][28] . Figure 1 ilustrates the sampling process described.…”

Section: Sampling and Analysis Techniquesmentioning

confidence: 99%

“…As can be seen in Table 1, the Al 2 O 3 , CaO, SiO 2 contents of these slags range between 15-25%, 47-52% and 13-17.6% by mass, respectively. Typical slag compositions for secondary refining of high basicity (2.8-3.6), saturated in CaO and MgO and with high content of alumina 25,36,37 . MgO content in the slag is in the range of 9 to 16 mass%.…”

Section: Effects Of the Slag Chemical Composition On Mgo Content Of Imentioning

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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“…Entretanto, esses procedimentos podem se ternar custosos e interferirem diretamente no processo de produção, gerando custos que só são justificados na produção de aços especiais (que possuem um maior valor agregado), como é o caso da utilização do desgaseificador a vácuo, utilizado em grande parte das siderúrgicas. [13,14,15] Levando em consideração o exposto acima, este trabalho tem por objetivo principal identificar, quantificar e classificar as inclusões presentes nas amostras analisadas, bem como observar se há um padrão de ocorrência das mesmas.…”

Section: Introductionunclassified

Análise Qualitativa E Quantitativa De Inclusões Em Um Aço Microligado

Christ¹,

Berger²,

Costa³

et al. 2017

ABM Proceedings

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Resumo A crescente demanda de aços com composições e propriedades controladas aumenta as exigências do controle de qualidade dos produtos acabados e dos constituintes deletérios, como as inclusões, que são agregados durante os processos de fabricação e acabamento. No presente trabalho foi realizada uma análise qualitativa e quantitativa das inclusões presentes em um aço microligado de partida de máquina, através da observação de imagens obtidas por microscópio ótico. A observação das imagens permitiu verificar uma falta de homogeneidade ou padrão na ocorrência das inclusões nas amostras e que as inclusões presentes eram do tipo óxidos glogulares e alumina. Palavras-chave: Inclusões não metálicas; Refino secundário; Metalografia.

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

Cited by 3 publications

References 13 publications

Analysis of Secondary Refining Slag Parameters with Focus on Inclusion Cleanliness

Analysis of Secondary Refining Slag Parameters with Focus on Inclusion Cleanliness

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

Análise Qualitativa E Quantitativa De Inclusões Em Um Aço Microligado

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