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Eutectic solidification mode of spheroidal graphite cast iron and graphitization  [PDF]
Hideo Nakae,Sanghoon Jung,Takayuki Kitazawa
China Foundry , 2007,
Abstract: The shrinkage and chilling tendency of spheroidal graphite (abbreviated SG) cast iron is much greater than that of the flake graphite cast iron in spite of its higher amount of C and Si contents. Why? The main reason should be the difference in their graphitization during the eutectic solidification. In this paper, we discuss the difference in the solidification mechanism of both cast irons for solving these problems using unidirectional solidification and the cooling curves of the spheroidal graphite cast iron. The eutectic solidification rate of the SG cast iron is controlled by the diffusion of carbon through the austenite shell, and the final thickness is 1.4 times the radius of the SG, therefore, the reduction of the SG size, namely, the increase in the number, is the main solution of these problems.
Wearing Quality of Austenitic, Duplex Cast Steel, Gray and Spheroidal Graphite Iron  [PDF]
S. Pietrowski
Archives of Foundry Engineering , 2012,
Abstract: The current work presents the research results of abrasion wear and adhesive wear at rubbing and liquid friction of new austenitic, austenitic-ferritic (“duplex”) cast steel and gray cast iron EN-GJL-250, spheroidal graphite iron EN-GJS-600-3, pearlitic with ledeburitic carbides and spheroidal graphite iron with ledeburitic carbides with a microstructure of the metal matrix: pearlitic, upper bainite, mixture of upper and lower bainite, martensitic with austenite, pearlitic-martensitic-bainitic-ausferritic obtained in the raw state. The wearing quality test was carried out on a specially designed and made bench. Resistance to abrasion wear was tested using sand paper P40. Resistance to adhesive wear was tested in interaction with steel C55 normalized, hardened and sulfonitrided. The liquid friction was obtained using CASTROL oil. It was stated that austenitic cast steel and “duplex” are characterized by a similar value of abrasion wear and adhesive wear at rubbing friction. The smallest decrease in mass was shown by the cast steel in interaction with the sulfonitrided steel C55. Austenitic cast steel and “duplex” in different combinations of friction pairs have a higher wear quality than gray cast iron EN-GJL- 250 and spheroidal graphite iron EN-GJS-600-3. Austenitic cast steel and “duplex” are characterized by a lower wearing quality than the spheroidal graphite iron with bainitic-martensitic microstructure. In the adhesive wear test using CASTROL oil the tested cast steels and cast irons showed a small mass decrease within the range of 1÷2 mg.
Influence of graphite precipitation shape and number on tensile strength of spheroidal cast iron manufactured in the foundry METAL-ODLEW Sp.J.  [PDF]
W. Or?owicz,M. Tupaj,M. Mróz,E. Guzik
Archives of Foundry Engineering , 2009,
Abstract: The study assesses influence of graphite precipitation shape and number on tensile strength of spheroidal cast iron manufactured under production conditions.
Influence of Manganese Content on the Dissolution of the Iron Carbide Phase (Cementite) during a Graphitization Anneal of Spheroidal Graphite Cast Iron  [PDF]
Jalel Briki,S. Ben Slima
Journal of Metallurgy , 2012, DOI: 10.1155/2012/841901
Abstract: The transformation of iron carbide cementite was investigated on spheroidal graphite containing different contents of manganese. The isothermal maintain were carried out at 600, 650, 700, and 750°C for periods of up to one hour. It was observed that the kinetics of graphitization is slowed even more than cast iron rich in manganese. 1. Introduction Graphitization heat treatment aims mainly at softening the structure by transforming the ferrite matrix. The corresponding treatment in the case of cast iron is usually time consuming and costly. This explains the number of studies devoted to the influence of the addition of alloying elements on the processes involved in the graphitization [1]. Copper, nickel, and silicon are commonly considered part graphitization. The effect of the molybdenum and/or manganese differs because of their power stabilizing against the carbides [2–4]. Thus, these elements cause a slowing of the kinetics of graphitization. The influence of manganese after the graphitization process of spheroidal graphite cast iron will be specifically studied. 2. Materials In Table 1 are collected the composition of the studied spheroidal graphite cast iron and hardness in the state of reception. Values of carbon content—measured using a LECO CS 244 type dosing—show that it is a hypoeutectic cast iron (1.7 < C < 4.3). Table 1: Composition in weight percent of the spheroidal graphite cast iron studied. In their “as received state” the samples under study have a ferrito-perlitic structure. Thus, the perlitic cementite leads to the formation of graphite, according to the following decomposition reaction (R): F e 3 C ? 3 F e + C . ( R ) This graphitization—similar to the bainitic or martensitic structure—is called secondary (as opposed to primary graphitization developed, either in the liquid metal or in the austenite supersaturated in carbon). The results obtained confirm the retarding effect exerted by manganese on the kinetics of graphitization of spheroidal graphite cast iron? In fact, we have the following.(i)As shown in Figures 1(a) and 1(b), the magnitude of the dilatometric expansion corresponding to the reaction (R) decreases as the manganese content increases from 0.9 to 2.15?wt%.(ii)The dilatometric curves recorded during isothermal heat treatment applied to the cast iron containing 2.15?wt% (Figure 1(a)) show the importance of the temperature parameter (θg) on the process of graphitization. Indeed, we note that cementite graphitized even faster than θg is close to Ac1. In addition, early maintenance develops a contraction whose amplitude
Anodic Dissolution of Spheroidal Graphite Cast Iron with Different Pearlite Areas in Sulfuric Acid Solutions  [PDF]
Yoshikazu Miyata,Yuki Kuwahara,Shukuji Asakura,Tadashi Shinohara,Takao Yakou,Keiichi Shiimoto
International Journal of Corrosion , 2013, DOI: 10.1155/2013/741378
Abstract: The rate equation of anodic dissolution reaction of spheroidal graphite cast iron in sulfuric acid solutions at 298?K has been studied. The cast irons have different areas of pearlite. The anodic Tafel slope of 0.043?V decade?1 and the reaction order with respect to the hydroxyl ion activity of 1 are obtained by the linear potential sweep technique. The anodic current density does not depend on the area of pearlite. There is no difference in the anodic dissolution reaction mechanisms between pure iron and spheroidal graphite cast iron. The anodic current density of the cast iron is higher than that of the pure iron. 1. Introduction Cast iron is widely used for pipes in neutral environments such as water and soil. A lot of experimental studies of cast iron for practical use were conducted [1–8]. A form of corrosion unique to cast irons is a selective leaching attack commonly referred to as graphitic corrosion [9, page 89]. A graphite network forms a corrosion-resistant phase called a graphitic layer. Therefore, the corrosion resistance of cast iron is said to be higher than that of steel. That is not necessarily the case. Laque reported that the corrosion rate of cast irons is lower than that of a steel in the atmosphere above the sea [2]. However, Paris and Bruniere [1] and Horikawa et al. [10] found that the corrosion rate of cast irons is nearly equal to that of steel in water and in atmosphere. Furthermore, a book said that graphitic corrosion does not occur in spheroidal graphite cast irons, because the graphite network does not exist [9, page 89], while another author reported that it occurs with both gray and spheroidal graphite cast irons [11]. These inconsistent results come from the complexity of graphitic corrosion. To elucidate the mechanisms of corrosion of cast iron, intensive studies are required. In this paper, the electrochemical dissolution of ferrous matrix is discussed. Cast iron is composed of pearlitic matrix, ferritic matrix, and graphite particles. The area of pearlite influences the physical properties such as tensile strength, elongation, and hardness [12]. Pearlitic matrix is a lamellar mixture of ferrite and cementite. Thus, the length of interfaces between ferrite and cementite becomes large with increasing pearlite area. Fontana [9, pages 28–31] and Trethewey and Chamberlain [13] described in their books that grain boundaries are high-energy areas and are more active chemically. The book by Evans said that regions near the grain boundaries may possess electrochemical properties different from those of the grain interiors
Shrinkage Behaviour of Spheroidal Graphite Cast Iron in Green and Dry Sand Molds for the Benchmarking of Solidification Simulation

Wenzhen LI,Baicheng LIU,Jiarong LI,

材料科学技术学报 , 2001,
Abstract: The effects of metallurgical and processing parameters on the formation of shrinkage cavities and porosities in spheroidal graphite cast iron have been studied, considering the parameters of carbon equivalent, inoculation, casting modulus, mold type (green or dry) and pouring temperature within specific ranges of these variables. Based on the orthogonal experiments, the metallurgical and processing parameters of the minimum casting shrinkage and the maximum casting shrinkage were obtained, and the effects of metallurgical and processing parameters on the formation of shrinkage cavities and porosities in spheroids graphite cast iron castings were discussed. Finally, two regression equations relating these variables to the formation of shrinkage porosity were derived based upon the orthogonal experiments conducted.
Colour Metallography of Cast Iron - Chapter 3: Spheroidal Graphite Cast Iron (Ⅱ)  [PDF]
Zhou Jiyang
China Foundry , 2010,
Abstract: Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology). Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour metallographic photos.Except for focusing on the effect of high carbon phases in cast iron, in this book, special attention is also paid to the effect of austenite on solidification, graphite morphology, and quality of cast iron; at the same time, the study on the solidification behaviours in the region around eutectic cells and its effects on mechanical properties of cast iron, are also emphasized.
Colour Metallography of Cast Iron - Chapter 3: Spheroidal Graphite Cast Iron (Ⅲ)  [PDF]
Zhou Jiyang
China Foundry , 2010,
Abstract: Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology). Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour metallographic photos.Except for focusing on the effect of high carbon phases in cast iron, in this book, special attention is also paid to the effect of austenite on solidification, graphite morphology, and quality of cast iron; at the same time, the study on the solidification behaviours in the region around eutectic cells and its effects on mechanical properties of cast iron, are also emphasized.
Colour Metallography of Cast Iron - Chapter 3: Spheroidal Graphite Cast Iron (Ⅰ)  [PDF]
Zhou Jiyang
China Foundry , 2010,
Abstract: Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology). Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour metallographic photos.Except for focusing on the effect of high carbon phases in cast iron, in this book, special attention is also paid to the effect of austenite on solidification, graphite morphology, and quality of cast iron; at the same time, the study on the solidification behaviours in the region around eutectic cells and its effects on mechanical properties of cast iron, are also emphasized.
Colour Metallography of Cast Iron - Chapter 3: Spheroidal Graphite Cast Iron (Ⅳ)  [PDF]
Zhou Jiyang
China Foundry , 2010,
Abstract: Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology). Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour metallographic photos.Except for focusing on the effect of high carbon phases in cast iron, in this book, special attention is also paid to the effect of austenite on solidification, graphite morphology, and quality of cast iron; at the same time, the study on the solidification behaviours in the region around eutectic cells and its effects on mechanical properties of cast iron, are also emphasized.
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