Abstract Non-metallic inclusions (NMIs) occur typically in low or very low volume fractions (from... more Abstract Non-metallic inclusions (NMIs) occur typically in low or very low volume fractions (from 10−2 in a high oxygen weld deposit to 10−5 in very clean bearing steels) but play an important role in many properties of steel. NMIs play a decisive role in processes involving ductile fracture, fatigue and corrosion, for instance. These are some of the properties more relevant to the performance of steel in structural and mechanical applications. Furthermore, NMIs may influence nucleation during phase transformations of steel. In this work, the relation of these properties to NMIs is reviewed, highlighting progress and difficulties in each area. Perhaps because of their very low volume fraction, NMIs are sometimes overlooked in the basic physical metallurgy education and their study is left to the realm of those interested in steelmaking. In the last decades a dramatic evolution in the understanding of their relationship to properties, however, has led to significant improvements in many steel products: the outstanding increase of fatigue life in automotive springs and in bearings is one of many such examples. It is concluded that steel improvement in many cases requires “inclusion engineering” and this can only be achieved through close collaboration between physical metallurgy, process metallurgy and steelmaking. Those who realized this have made significant progress in steel development in recent decades as highlighted in this short review.
Abstract Non-metallic inclusions (NMIs) play a key role in many important properties of steel, in... more Abstract Non-metallic inclusions (NMIs) play a key role in many important properties of steel, influencing both processing and application of steel products. In this work, the current understanding of the origin and classification of NMIs is reviewed, highlighting the dramatic development of the last decades. This includes the discussion of the thermodynamics of inclusion formation and the current knowledge on the effects of melt shop processing variable on NMIs composition, amount and size distribution. The development of inclusion engineering – tailoring the process to obtain the desired NMIs is highlighted and the development in selected areas – tire cord, springs and bearing steels as well as prevention of nozzle clogging – is used to illustrate this development. The promising field of “oxide metallurgy” is also discussed in the context of inclusion engineering. Finally, the difficulties in meaningfully characterizing and quantifying NMIs are briefly commented. In summary it is concluded that inclusion control in steels has evolved significantly in the last decades. This is due to the progress in understanding the interplay between thermodynamics, steel and slag chemical composition as well as melt shop processing. This made possible the tailoring of non-metallic inclusions via processing, to optimize steel properties. Nonetheless, some important problems remain and must still be solved to improve inclusion control and optimization.
This chapter introduces the basic concepts of the phases and constituents present in the simpler ... more This chapter introduces the basic concepts of the phases and constituents present in the simpler steels in conditions near equilibrium. The discussion focuses on the iron-carbon (Fe–C) system. Understanding these concepts is fundamental for a proper understanding of the transformations that occur during steel solidification, heat treatments, and thermomechanical processing. Discussion of the Fe–C system is of paramount importance to understanding many phenomena that also occur in complex alloy steels. The combination of chemical composition and structure defines the properties and hence the performance of steels. Chemical composition is controlled essentially during the steelmaking processes, although the composition close to the part surface can be affected by thermochemical treatments in the solid state. Structure, on the other hand, is altered by the combination of deformation and temperature change, normally grouped under the name of thermomechanical treatments. Producing phase transformations between the two main crystal structures of iron, body-centered cubic (BCC) and face-centered cubic (FCC) and forming structures other than equilibrium structures with interesting properties in terms of application and with reasonable stability are possibly the two main reasons that explain the wide use of steels as industrial materials. A main objective of this book is to present the structures that result from applying different thermomechanical treatments of steels with various chemical compositions, in particular the size scale evaluated through metallography. Underlying the effect of these treatments on steels with different chemical compositions is the concept of phase transformation. The way steel undergoes phase transformations in the different stages of its processing is a critical factor in defining the features and properties of the structures formed. While the object of this book is not the in-depth study of phase transformations, the reader should be familiar with the concepts that control these transformations. Here, only the fundamental aspects essential to understanding the features presented are discussed; excellent literature is available on the subject at different levels of complexity in [1–4].
ABSTRACT The model proposed by Speer et al. to calculate the constrained carbon equilibrium is ex... more ABSTRACT The model proposed by Speer et al. to calculate the constrained carbon equilibrium is expanded to include any number Of substitutional solutes and coded with the MatLab and Thermo-Calc programs. This model is used to evaluate the effect of Al, Cr, Cu, Mn, Mo, Ni and Si solutes on the final austenite carbon concentration of ternary Fe-X-C alloys. Comparison is also made with the carbon concentration measured experimentally in some Transformation Induced Plasticity steels.
Available online xxx Keywords: Non-metallic inclusions Fracture Fatigue Ductility Steel Steelmaki... more Available online xxx Keywords: Non-metallic inclusions Fracture Fatigue Ductility Steel Steelmaking a b s t r a c t Non-metallic inclusions (NMIs) occur typically in low or very low volume fractions (from 10 −2 in a high oxygen weld deposit to 10 −5 in very clean bearing steels) but play an important role in many properties of steel. NMIs play a decisive role in processes involving ductile fracture, fatigue and corrosion, for instance. These are some of the properties more relevant to the performance of steel in structural and mechanical applications. Furthermore, NMIs may influence nucleation during phase transformations of steel. In this work, the relation of these properties to NMIs is reviewed, highlighting progress and difficulties in each area. Perhaps because of their very low volume fraction, NMIs are sometimes overlooked in the basic physical metallurgy education and their study is left to the realm of those interested in steelmaking. In the last decades a dramatic evolution in the understanding of their relationship to properties, however, has led to significant improvements in many steel products: the outstanding increase of fatigue life in automotive springs and in bearings is one of many such examples. It is concluded that steel improvement in many cases requires "inclusion engineering" and this can only be achieved through close collaboration between physical metallurgy, process metallurgy and steelmaking. Those who realized this have made significant progress in steel development in recent decades as highlighted in this short review.
Hubertus Colpaert, updated and translated by André Luiz V. da Costa e Silva Ó ASM International 2... more Hubertus Colpaert, updated and translated by André Luiz V. da Costa e Silva Ó ASM International 2017 This chapter introduces the basic concepts of the phases and constituents present in the simpler steels in conditions near equilibrium. The discussion focuses on the iron-carbon (Fe-C) system. Understanding these concepts is fundamental for a proper understanding of the transformations that occur during steel solidification, heat treatments, and thermomechanical processing. Discussion of the Fe-C system is of paramount importance to understanding many phenomena that also occur in complex alloy steels. The combination of chemical composition and structure defines the properties and hence the performance of steels. Chemical composition is controlled essentially during the steelmaking processes, although the composition close to the part surface can be affected by thermochemical treatments in the solid state. Structure, on the other hand, is altered by the combination of deformation and temperature change, normally grouped under the name of thermome-chanical treatments. Producing phase transformations between the two main crystal structures of iron, body-centered cubic (BCC) and face-centered cubic (FCC) and forming structures other than equilibrium structures with interesting properties in terms of application and with reasonable stability are possibly the two main reasons that explain the wide use of steels as industrial materials. A main objective of this book is to present the structures that result from applying different thermomechanical treatments of steels with various chemical compositions, in particular the size scale evaluated through metallography. Underlying the effect of these treatments on steels with different chemical compositions is the concept of phase transformation. The way steel undergoes phase transformations in the different stages of its processing is a critical factor in defining the features and properties of the structures formed. While the object of this book is not the in-depth study of phase transformations, the reader should be familiar with the concepts that control these transformations. Here, only the fundamental aspects essential to understanding the features presented are discussed; excellent literature is available on the subject at different levels of complexity in [1-4]. At atmospheric pressure, iron can have two solid crystal structures (BCC or FCC), depending on temperature, and is able to transform into the liquid state (the conditions under which iron is present as a vapor are less interesting to metallurgy). Alloying elements added to iron may help make one or the other structures more stable. They may also form new, important phases in steel. For this reason, the first important information related to the possible structures of an iron-base alloy is to understand the equilibrium state of the alloy at different temperatures. In metallurgy this information is classically presented in the equilibrium phase diagrams. These diagrams are constructed directly from the collection and consolidation of the results of experiments.
Resumo Visando garantir o nível de qualidade dos produtos e o controle do processamento do aço pa... more Resumo Visando garantir o nível de qualidade dos produtos e o controle do processamento do aço para atender aos requisitos dos clientes e das normas técnicas aplicáveis e manter-se competitivo no mercado de aços longos com redução contínua de custos, um dos grandes desafios das aciarias elétricas é promover o aumento do rendimento de suas ferro-ligas melhorando ao mesmo tempo os processos de desoxidação e dessulfuração, além da limpeza interna do banho. Este trabalho teve como objetivo avaliar o efeito da adição de carbureto de cálcio durante o vazamento das corridas do aço 1026-D nestas variáveis, através da análise estatística e termodinâmica de dados de corridas experimentais, com e sem adição de carbureto de cálcio. Foi demonstrado que a adição desse insumo melhora de forma significativa os parâmetros metalúrgicos de qualidade do material e reduz o custo de transformação para a fabricação desse produto através da redução do consumo de ferro-ligas. Palavras-chave: Desoxidação; Dessulfuração; Carbureto de cálcio; Ferro-ligas. IMPROVEMENT OF ALLOYS-IRON'S YIELD AND THE DEOXIDATION AND DESULPHURIZATION PROCESSES WITH THE CALCIUM CARBIDE USE Abstract Aiming to guarantee the quality level of products and steel processing control to meet customers' requirements and standards further applicable rules, remain competitive in the long steel market aiming ongoing cost reduction, one of the higher challenge on electric steelworks is promoting alloy iron yield improve, improving the same time the deoxidation and desulphurization processes thus the metallic internal cleansing. This work aimed measure the gains talked regarding the addition of calcium carbide during the tapping of 1026-D steel, through experimental data reviews in statistic and through a mass balance evaluation did for analyze the alloys iron yields. Was demonstrated that the calcium carbide addition improve, significantly, the material quality metallurgical parameters and decrease the transformation cost for product fabrication through alloy iron consume decrease.
Resumo O enxofre no aço é, normalmente, um residual indesejável, afetando negativamente proprieda... more Resumo O enxofre no aço é, normalmente, um residual indesejável, afetando negativamente propriedades como ductilidade tenacidade, conformabilidade, soldabilidade e resistência à corrosão. Desde os anos 1970 a prática mais comum é dessulfurar o gusa fora dos altos-fornos, evitando, sempre que possível, a dessulfuração do aço em forno panela. Isto permite vazamento de gusa com teores de enxofre mais elevados do alto-forno, reduzindo os custos de produção desde reator. Termodinamicamente, a dessulfuração do gusa é favorável, devido as condições redutoras e a interação do enxofre com o carbono. Operacionalmente, o gusa pode ser dessulfurado em carros torpedos ou em panelas de transferência, através da adição de diversos reagentes. Para controlar o processo de dessulfuração é necessário conhecer a cinética do processo. Este trabalho descreve estudos iniciais para a melhoria do modelo de controle da dessulfuração em carro torpedo na CSN através da injeção de carbureto de cálcio em pó. Palavras-chave: Dessulfuração; Enxofre; Gusa; Modelo matemático. Abstract Sulfur in steel is usually considered an undesirable residual, causing loss of properties such as ductility, toughness, formability, weldability and corrosion resistance. Since the 1970s the practice is to desulphurize the pig iron out of the blast furnaces, producing pig iron with high sulfur but reducing production costs in this reactor. Due to the very low oxygen potential in the pig iron and the carbon sulfur interaction, pig iron desulfurization is thermodynamically very advantageous. This can be done either in torpedo cars or in transfer ladles. In the present work the initial studies to develop an improved model to control de pig iron desulfurization process in the torpedo cars of CSN through the injection of calcium carbide is described.
Abstract Non-metallic inclusions (NMIs) occur typically in low or very low volume fractions (from... more Abstract Non-metallic inclusions (NMIs) occur typically in low or very low volume fractions (from 10−2 in a high oxygen weld deposit to 10−5 in very clean bearing steels) but play an important role in many properties of steel. NMIs play a decisive role in processes involving ductile fracture, fatigue and corrosion, for instance. These are some of the properties more relevant to the performance of steel in structural and mechanical applications. Furthermore, NMIs may influence nucleation during phase transformations of steel. In this work, the relation of these properties to NMIs is reviewed, highlighting progress and difficulties in each area. Perhaps because of their very low volume fraction, NMIs are sometimes overlooked in the basic physical metallurgy education and their study is left to the realm of those interested in steelmaking. In the last decades a dramatic evolution in the understanding of their relationship to properties, however, has led to significant improvements in many steel products: the outstanding increase of fatigue life in automotive springs and in bearings is one of many such examples. It is concluded that steel improvement in many cases requires “inclusion engineering” and this can only be achieved through close collaboration between physical metallurgy, process metallurgy and steelmaking. Those who realized this have made significant progress in steel development in recent decades as highlighted in this short review.
Abstract Non-metallic inclusions (NMIs) play a key role in many important properties of steel, in... more Abstract Non-metallic inclusions (NMIs) play a key role in many important properties of steel, influencing both processing and application of steel products. In this work, the current understanding of the origin and classification of NMIs is reviewed, highlighting the dramatic development of the last decades. This includes the discussion of the thermodynamics of inclusion formation and the current knowledge on the effects of melt shop processing variable on NMIs composition, amount and size distribution. The development of inclusion engineering – tailoring the process to obtain the desired NMIs is highlighted and the development in selected areas – tire cord, springs and bearing steels as well as prevention of nozzle clogging – is used to illustrate this development. The promising field of “oxide metallurgy” is also discussed in the context of inclusion engineering. Finally, the difficulties in meaningfully characterizing and quantifying NMIs are briefly commented. In summary it is concluded that inclusion control in steels has evolved significantly in the last decades. This is due to the progress in understanding the interplay between thermodynamics, steel and slag chemical composition as well as melt shop processing. This made possible the tailoring of non-metallic inclusions via processing, to optimize steel properties. Nonetheless, some important problems remain and must still be solved to improve inclusion control and optimization.
This chapter introduces the basic concepts of the phases and constituents present in the simpler ... more This chapter introduces the basic concepts of the phases and constituents present in the simpler steels in conditions near equilibrium. The discussion focuses on the iron-carbon (Fe–C) system. Understanding these concepts is fundamental for a proper understanding of the transformations that occur during steel solidification, heat treatments, and thermomechanical processing. Discussion of the Fe–C system is of paramount importance to understanding many phenomena that also occur in complex alloy steels. The combination of chemical composition and structure defines the properties and hence the performance of steels. Chemical composition is controlled essentially during the steelmaking processes, although the composition close to the part surface can be affected by thermochemical treatments in the solid state. Structure, on the other hand, is altered by the combination of deformation and temperature change, normally grouped under the name of thermomechanical treatments. Producing phase transformations between the two main crystal structures of iron, body-centered cubic (BCC) and face-centered cubic (FCC) and forming structures other than equilibrium structures with interesting properties in terms of application and with reasonable stability are possibly the two main reasons that explain the wide use of steels as industrial materials. A main objective of this book is to present the structures that result from applying different thermomechanical treatments of steels with various chemical compositions, in particular the size scale evaluated through metallography. Underlying the effect of these treatments on steels with different chemical compositions is the concept of phase transformation. The way steel undergoes phase transformations in the different stages of its processing is a critical factor in defining the features and properties of the structures formed. While the object of this book is not the in-depth study of phase transformations, the reader should be familiar with the concepts that control these transformations. Here, only the fundamental aspects essential to understanding the features presented are discussed; excellent literature is available on the subject at different levels of complexity in [1–4].
ABSTRACT The model proposed by Speer et al. to calculate the constrained carbon equilibrium is ex... more ABSTRACT The model proposed by Speer et al. to calculate the constrained carbon equilibrium is expanded to include any number Of substitutional solutes and coded with the MatLab and Thermo-Calc programs. This model is used to evaluate the effect of Al, Cr, Cu, Mn, Mo, Ni and Si solutes on the final austenite carbon concentration of ternary Fe-X-C alloys. Comparison is also made with the carbon concentration measured experimentally in some Transformation Induced Plasticity steels.
Available online xxx Keywords: Non-metallic inclusions Fracture Fatigue Ductility Steel Steelmaki... more Available online xxx Keywords: Non-metallic inclusions Fracture Fatigue Ductility Steel Steelmaking a b s t r a c t Non-metallic inclusions (NMIs) occur typically in low or very low volume fractions (from 10 −2 in a high oxygen weld deposit to 10 −5 in very clean bearing steels) but play an important role in many properties of steel. NMIs play a decisive role in processes involving ductile fracture, fatigue and corrosion, for instance. These are some of the properties more relevant to the performance of steel in structural and mechanical applications. Furthermore, NMIs may influence nucleation during phase transformations of steel. In this work, the relation of these properties to NMIs is reviewed, highlighting progress and difficulties in each area. Perhaps because of their very low volume fraction, NMIs are sometimes overlooked in the basic physical metallurgy education and their study is left to the realm of those interested in steelmaking. In the last decades a dramatic evolution in the understanding of their relationship to properties, however, has led to significant improvements in many steel products: the outstanding increase of fatigue life in automotive springs and in bearings is one of many such examples. It is concluded that steel improvement in many cases requires "inclusion engineering" and this can only be achieved through close collaboration between physical metallurgy, process metallurgy and steelmaking. Those who realized this have made significant progress in steel development in recent decades as highlighted in this short review.
Hubertus Colpaert, updated and translated by André Luiz V. da Costa e Silva Ó ASM International 2... more Hubertus Colpaert, updated and translated by André Luiz V. da Costa e Silva Ó ASM International 2017 This chapter introduces the basic concepts of the phases and constituents present in the simpler steels in conditions near equilibrium. The discussion focuses on the iron-carbon (Fe-C) system. Understanding these concepts is fundamental for a proper understanding of the transformations that occur during steel solidification, heat treatments, and thermomechanical processing. Discussion of the Fe-C system is of paramount importance to understanding many phenomena that also occur in complex alloy steels. The combination of chemical composition and structure defines the properties and hence the performance of steels. Chemical composition is controlled essentially during the steelmaking processes, although the composition close to the part surface can be affected by thermochemical treatments in the solid state. Structure, on the other hand, is altered by the combination of deformation and temperature change, normally grouped under the name of thermome-chanical treatments. Producing phase transformations between the two main crystal structures of iron, body-centered cubic (BCC) and face-centered cubic (FCC) and forming structures other than equilibrium structures with interesting properties in terms of application and with reasonable stability are possibly the two main reasons that explain the wide use of steels as industrial materials. A main objective of this book is to present the structures that result from applying different thermomechanical treatments of steels with various chemical compositions, in particular the size scale evaluated through metallography. Underlying the effect of these treatments on steels with different chemical compositions is the concept of phase transformation. The way steel undergoes phase transformations in the different stages of its processing is a critical factor in defining the features and properties of the structures formed. While the object of this book is not the in-depth study of phase transformations, the reader should be familiar with the concepts that control these transformations. Here, only the fundamental aspects essential to understanding the features presented are discussed; excellent literature is available on the subject at different levels of complexity in [1-4]. At atmospheric pressure, iron can have two solid crystal structures (BCC or FCC), depending on temperature, and is able to transform into the liquid state (the conditions under which iron is present as a vapor are less interesting to metallurgy). Alloying elements added to iron may help make one or the other structures more stable. They may also form new, important phases in steel. For this reason, the first important information related to the possible structures of an iron-base alloy is to understand the equilibrium state of the alloy at different temperatures. In metallurgy this information is classically presented in the equilibrium phase diagrams. These diagrams are constructed directly from the collection and consolidation of the results of experiments.
Resumo Visando garantir o nível de qualidade dos produtos e o controle do processamento do aço pa... more Resumo Visando garantir o nível de qualidade dos produtos e o controle do processamento do aço para atender aos requisitos dos clientes e das normas técnicas aplicáveis e manter-se competitivo no mercado de aços longos com redução contínua de custos, um dos grandes desafios das aciarias elétricas é promover o aumento do rendimento de suas ferro-ligas melhorando ao mesmo tempo os processos de desoxidação e dessulfuração, além da limpeza interna do banho. Este trabalho teve como objetivo avaliar o efeito da adição de carbureto de cálcio durante o vazamento das corridas do aço 1026-D nestas variáveis, através da análise estatística e termodinâmica de dados de corridas experimentais, com e sem adição de carbureto de cálcio. Foi demonstrado que a adição desse insumo melhora de forma significativa os parâmetros metalúrgicos de qualidade do material e reduz o custo de transformação para a fabricação desse produto através da redução do consumo de ferro-ligas. Palavras-chave: Desoxidação; Dessulfuração; Carbureto de cálcio; Ferro-ligas. IMPROVEMENT OF ALLOYS-IRON'S YIELD AND THE DEOXIDATION AND DESULPHURIZATION PROCESSES WITH THE CALCIUM CARBIDE USE Abstract Aiming to guarantee the quality level of products and steel processing control to meet customers' requirements and standards further applicable rules, remain competitive in the long steel market aiming ongoing cost reduction, one of the higher challenge on electric steelworks is promoting alloy iron yield improve, improving the same time the deoxidation and desulphurization processes thus the metallic internal cleansing. This work aimed measure the gains talked regarding the addition of calcium carbide during the tapping of 1026-D steel, through experimental data reviews in statistic and through a mass balance evaluation did for analyze the alloys iron yields. Was demonstrated that the calcium carbide addition improve, significantly, the material quality metallurgical parameters and decrease the transformation cost for product fabrication through alloy iron consume decrease.
Resumo O enxofre no aço é, normalmente, um residual indesejável, afetando negativamente proprieda... more Resumo O enxofre no aço é, normalmente, um residual indesejável, afetando negativamente propriedades como ductilidade tenacidade, conformabilidade, soldabilidade e resistência à corrosão. Desde os anos 1970 a prática mais comum é dessulfurar o gusa fora dos altos-fornos, evitando, sempre que possível, a dessulfuração do aço em forno panela. Isto permite vazamento de gusa com teores de enxofre mais elevados do alto-forno, reduzindo os custos de produção desde reator. Termodinamicamente, a dessulfuração do gusa é favorável, devido as condições redutoras e a interação do enxofre com o carbono. Operacionalmente, o gusa pode ser dessulfurado em carros torpedos ou em panelas de transferência, através da adição de diversos reagentes. Para controlar o processo de dessulfuração é necessário conhecer a cinética do processo. Este trabalho descreve estudos iniciais para a melhoria do modelo de controle da dessulfuração em carro torpedo na CSN através da injeção de carbureto de cálcio em pó. Palavras-chave: Dessulfuração; Enxofre; Gusa; Modelo matemático. Abstract Sulfur in steel is usually considered an undesirable residual, causing loss of properties such as ductility, toughness, formability, weldability and corrosion resistance. Since the 1970s the practice is to desulphurize the pig iron out of the blast furnaces, producing pig iron with high sulfur but reducing production costs in this reactor. Due to the very low oxygen potential in the pig iron and the carbon sulfur interaction, pig iron desulfurization is thermodynamically very advantageous. This can be done either in torpedo cars or in transfer ladles. In the present work the initial studies to develop an improved model to control de pig iron desulfurization process in the torpedo cars of CSN through the injection of calcium carbide is described.
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