Calcium treatment of medium carbon steel grades for machinability enhancement: from the theory to industrial practice

Kirsch-Racine, A.; Bomont-Arzur, Anne; Confente, M.

doi:10.1051/metal:2008003

Cited by 14 publications

(14 citation statements)

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“…Figure 4 In steel with high S and Al concentrations, liquid inclusions cannot form without some CaS precipitation. According to Kirsch-Racine et al [6] , to ensure both good castability and liquid inclusions (or those with a high liquid content), the level of calcium must be between CA and liquid oxides. Gaye [27] demonstrated that, for a steel with Al ¼ 0.05% and S ¼ 0.035%, the CaO content in inclusions is limited to 40% so as to avoid the formation of CaS.…”

Section: Thermodynamic Analysismentioning

confidence: 99%

“…[2] With regard to aluminum-killed steel, Eriksson and Pelton [3] carried out a critical assessment of both the thermodynamic properties and phase diagrams of the CaO-Al 2 O 3 system. The thermodynamic model of steel deoxidation has been described by Jung et al [4] Few studies in the literature [5][6][7] address calcium treatment for aluminum-killed steel with sulfur content higher than 0.015% (engineering steel with improved machinability). In previous studies, [8] thermodynamics were used to evaluate the Al, Ca, S, and O content at which liquid or partially liquid inclusions are formed in order to optimize the castability of SAE 8620 steel.…”

Section: Introductionmentioning

confidence: 99%

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Study of Inclusions in High Sulfur, Al-Killed Ca-Treated Steel via Experiments and Thermodynamic Calculations

Bielefeldt

Vilela

2015

steel research int.

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In the production of special steels, inclusions have a significant influence on final product quality. Moreover, there is a growing need for constant improvement of mechanical and machinability properties, such as in the production of complex pieces for the automotive applications. The main objective of this study was to conduct a thermodynamic study aimed at preventing clogging problems during continuous casting (CC) and the formation of undesirable inclusions. Alumina (Al2O3), spinels, and calcium sulfide (CaS) are potential sources of defects during rolling and steel forging. The specific goals of this study were: (1) To determine the phases and compounds formed in the inclusions as a function of composition and casting temperature adopted for high sulfur Al‐killed Ca‐treated steel, and (2) To establish chemical composition conditions resulting in the formation of less harmful inclusions for steel castability. Based on the literature and previous studies by the authors, calculations were carried out using FactSage commercial software and related databases. The calculations were performed using the steel temperature and chemical composition in the CC tundish. The results of these calculations were used to estimate the composition of steel and non‐metallic inclusions (oxides and sulfides) at the given steel temperature. Based on these calculations, it was predicted a calcium content range where inclusions contained a high proportion of liquid phase (i.e., “liquid window”). The results of thermodynamic simulation were compared to industrial outcomes in terms of inclusion composition and casting index. The thermodynamic predictions were validated and confirmed by industrial results.

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Section: Thermodynamic Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study of Inclusions in High Sulfur, Al-Killed Ca-Treated Steel via Experiments and Thermodynamic Calculations

Bielefeldt

Vilela

2015

steel research int.

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“…Em aços de S e Al elevados, muitas vezes não é possível a formação de inclusões líquidas sem a presença de CaS. Segundo Kirsch-Racine, Bornont-Arzun e Contente, (10) um nível de cálcio para garantir boa lingotabilidade e inclusões As Figuras 5 e 6 mostram a evolução dos teores de alumínio e cálcio dissolvidos no aço, dependendo do teor de cálcio total, para as condições do aço SAE 8620 (Al = 275 ppm e O total = 18 ppm). As curvas apresentam uma inflexão cada vez que ocorre a formação de um dos óxidos.…”

Section: Resultsunclassified

Estudo Termodinâmico De Inclusões Não-Metálicas Em Aço Acalmado Ao Alumínio E Tratado Com Cálcio

Bielefeldt

Vilela

2011

TMM

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ResumoO objetivo geral do trabalho foi o estudo da formação de inclusões não-metálicas no lingotamento contínuo (LC) para um aço acalmado ao alumínio e tratado com cálcio (SAE 8620). Os objetivos específicos foram: 1) A obtenção das fases e compostos formados nas inclusões em função da composição e temperatura de lingotamento adotadas para o aço SAE 8620. 2) Estabelecer condições de composição química do aço para a formação de inclusões menos deletérias à lingotabilidade do SAE 8620. Com base em trabalhos da literatura e em trabalhos anteriores dos autores, simulações foram realizadas via FactSage e seus bancos de dados. As simulações foram realizadas utilizando a composição química global do aço SAE 8620 no distribuidor de LC. O resultado é a composição do aço e inclusões não-metálicas (óxidos e sulfetos) na temperatura de interesse. Os resultados mostraram a formação de diferentes óxidos sólidos e a formação de fase líquida nas inclusões pela variação do teor de cálcio no aço. Foi possível determinar a composição das inclusões como função dos teores de alumínio e cálcio no aço SAE 8620. Para uma determinada composição e temperatura do aço SAE 8620, também foi possível estabelecer uma faixa de teor de cálcio onde as inclusões são formadas por fase líquida predominante. Foi ainda possível calcular o percentual de fase líquida e sólida nas inclusões, bem como sua composição em termos de óxidos. Palavras-chave: Inclusões; Tratamento com cálcio; FactSage. THERMODYNAMIC STUDY OF NON-METALLIC INCLUSIONS IN AL-KILLED CALCIUM TREATED STEEL AbstractThe main goal was the study of non-metallic inclusion formation in the continuous casting (CC) for Al-killed, calcium treated steel (SAE 8620). The specific goals were: 1) To obtain the phases and compounds formed in the inclusions as a function of composition and casting temperature adopted for the SAE 8620 steel. 2) To establish conditions of steel chemical composition for the formation of less harmful inclusions to the SAE 8620 castability. Based in the literature and previous work of the authors, were carried out simulations using the software FactSage and databases. The simulations were realized using the global chemical composition of SAE 8620 steel in the CC tundish. The results were steel and non-metallic inclusions (oxides and sulphites) composition in the aimed temperature. The results showed the formation of different solid oxides and the formation of liquid phase in the inclusions by the variation of calcium content in the steel. It was possible to determine the inclusion composition as a function of aluminum and calcium content of SAE 8620 steel. For the specific composition and temperature of SAE 8620 steel, it was possible to establish a range of calcium content were the inclusions are formed by predominant liquid phase. It was possible to calculate the percent of liquid and solid phase in the inclusions, as well the composition in terms of oxides.

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“…Grades for the mechanical parts of engineering industry are often Al‐killed to meet the requirements of the customers in terms of grain size and fatigue resistance 1. The sulfur contents in these grades are controlled in the range of 200–300 ppm in order to improve their machining properties 2.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Sulfur Addition to the High Basicity Slag on the Sulfur, Aluminum, and Cleanliness of High Sulfur Al‐Killed Molten Steel

Jiang

Cheng

Qian

et al. 2013

steel research int.

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In the present work, the influence of sulfur addition to the high basicity slag on the Al‐killed molten steel with high sulfur content was investigated by using a vacuum induction furnace at 1873 K in MgO crucibles. CaO–SiO2–Al2O3–MgO–CaS slags were used to study the effect of high basicity slags with different CaS contents on sulfur loss, aluminum loss, and total oxygen content in the molten steel. It is shown that the sulfur content in the molten steel decreased with the time, and the addition of CaS into the slag can reduce the sulfur loss in the molten steel. Moreover, there was a decreasing tendency of the aluminum content in the molten steel with the time, and the addition of CaS into the slag can reduce the aluminum loss in the molten steel. Total oxygen content in the molten steel first increased and then decreased with the time when no CaS was added into the slag. However, it decreased monotonically with the time when the addition of CaS was made into the slag.

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Calcium treatment of medium carbon steel grades for machinability enhancement: from the theory to industrial practice

Cited by 14 publications

References 0 publications

Study of Inclusions in High Sulfur, Al-Killed Ca-Treated Steel via Experiments and Thermodynamic Calculations

Study of Inclusions in High Sulfur, Al-Killed Ca-Treated Steel via Experiments and Thermodynamic Calculations

Estudo Termodinâmico De Inclusões Não-Metálicas Em Aço Acalmado Ao Alumínio E Tratado Com Cálcio

Evaluation of Sulfur Addition to the High Basicity Slag on the Sulfur, Aluminum, and Cleanliness of High Sulfur Al‐Killed Molten Steel

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