Precipitation and evolution of nodular graphite during solidification process of ductile iron

Liu, Jinhai; Yan, Jian-shuai; Zhao, Xinze; Fu, Bin-guo; Xue, Haitao; Zhang, Guixian; Yang, Penghui

doi:10.1007/s41230-020-0042-2

Cited by 14 publications

(7 citation statements)

References 29 publications

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“…The research findings indicate that eutectic ductile cast iron melt exhibits a higher degree of graphitization capability. Therefore, when considering hypoeutectic and hypereutectic ductile iron in comparison to eutectic ductile iron, it is observed that eutectic ductile iron exhibits a greater capacity for self-feeding, as noted by Liu et al (2020) and Anjos and Silva Ribeiro (2018).…”

Section: Effect Of Carbon Equivalent and Inoculationmentioning

confidence: 99%

Investigation on effect of carbon equivalent and inoculation on the solidification and shrinkage tendency of ductile cast iron using thermal analysis

Sangame,

Reddy

2023

MMMS

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PurposeThe foundry industry incurs additional costs as a result of defective castings. Shrinkage defects are a frequent problem in ductile iron castings. It is still essential to understand how shrinkage porosity varies in size when the ductile iron composition changes. This information can be used to produce high-quality cast parts and determine the best processing conditions. The objective of this research paper is to examine the effect of carbon equivalent and inoculation on the morphology of the shrinkage defect using thermal analysis.Design/methodology/approachThis study focuses on certain thermal analysis parameters, such as the angle of the first derivative curve at the solidus temperature, recalescence and its relationships to graphite nucleation and shrinkage tendency. The results of thermal analysis in terms of the cooling curve and its derivative parameters, and thorough characterizations of the shrinkage observed in cup castings produced with various melt compositions and inoculation are presented in the current study.FindingsThe proportion of caved surfaces and macro shrinkage porosity defects has been reduced as the carbon equivalent of melt increases from hypoeutectic to a hypereutectic composition. The composition that is slightly hypereutectic has the lowest shrinkage propensity. Although inoculation reduces shrinkage, the importance of this parameter differs depending on the carbon equivalent.Originality/valueThe percentage of macro shrinkage porosity and the angle that the cooling rate curve forms are strongly correlated. It is found that the macro shrinkage size decreases as the angle of the first derivative curve at the solidus temperature is reduced. Further, lower macroporosity is produced by a metal that has a higher nodule count in association with a greater cooling rate toward the end of the solidification process.

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Section: Effect Of Carbon Equivalent and Inoculationmentioning

confidence: 99%

Investigation on effect of carbon equivalent and inoculation on the solidification and shrinkage tendency of ductile cast iron using thermal analysis

Sangame,

Reddy

2023

MMMS

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“…Cast iron with spheroidal graphite is a modern material with excellent mechanical properties [1][2][3]. Especially ferrite cast iron with spheroidal graphite achieves toughness and strength comparable with steel [4].…”

Section: Introductionmentioning

confidence: 99%

“…Mechanical properties of cast iron are influenced by the graphite shape, nodularity and distribution [6,7]. A large amount of evenly distributed spheroidal graphite with high nodularity and small diameter has a positive influence on the cast iron properties [2]. Graphite is found standardly in cast iron in the form of flakes, however, after Mg or Ce addition, spheroidal graphite is formed [4,8] and the material mechanical properties change.…”

Section: Introductionmentioning

confidence: 99%

implementation of cored wire technology into production of ductile iron for castings designated for extreme conditions

Socha

Gryc

KOZA

et al. 2022

METAL 2022 Conference Proeedings

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Presented paper deals with the technology of production of ductile iron on industrial scale. Particularly, the material in question is EN-GJS-400-18-LT, which is suitable for castings intended for extreme conditions. Drawing on previous works, most attention has been paid to the implementation of the cored wire technology for modification and primary inoculation. Two technological options were compared, namely modification and primary inoculation by the pour method in the ladle and modification and primary inoculation by the cored wire using a twin-core feeder. Test samples within the inlet system of the moulds were cast during the pouring process to analyse the chemical composition, evaluate the microstructure and perform mechanical tests without interfering with the casting itself. The chemical composition was determined by optical emission spectrometry and combustion analysis. Metallographic analysis and microstructure evaluation were performed by optical microscopy and image analysis. Mechanical properties testing was focused on tensile test, impact test and hardness test. It was demonstrated that the foundry is capable of producing ductile iron of the required quality with the adoption of modern cored wire technology.

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“…On-line inspection of the solidification process using the thermal analysis technique is currently a rapid method for the inspection of cast iron [ 13 ]. Kanno et al [ 14 , 15 ] used the thermal analysis method to predict the shrinkage tendency of spheroidal graphite iron, and a mathematical fitting analysis between the thermal analysis characteristic values and shrinkage tendency was performed to obtain the relationship index for predicting the shrinkage.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Shrinkage in Compacted Graphite Iron and Prediction of Shrinkage Tendency

et al. 2022

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Shrinkage greatly influences the mechanical and fatigue properties of compacted graphite iron and it is necessary in order to study the causes of shrinkage in compacted graphite iron and to predict it effectively. In this paper, a kind of cylindrical necking test sample was designed to evaluate the shrinkage in compacted graphite iron, and a method to calculate the size of shrinkage was proposed. By observing the microstructure around the shrinkage zone, it is concluded that concentrated shrinkage mainly appears in the solidification region where the dendritic gap is closed, and the isolated shrinkage mainly occurs in the final solidification region, and the supersaturated carbon elements are gathered on the surface of the shrinkage. The cause of shrinkage in compacted graphite iron is caused by its solidification method, where the austenite dendrites and the eutectic clusters are generated close to the melt zone during the solidification process, leading to the inability to feed the shrinkage. Based on the thermodynamic analysis, the equations between the volume change of each phase, solid phase rate, and time during solidification of compacted graphite iron were established to theoretically explain the formation mechanism of the shrinkage. Taking nine parameters such as the chemical elements and characteristic values of thermal analysis as the input nods, a four-layer BP neural network model for predicting the size of shrinkage in compacted graphite iron was constructed, and the R-squared of the model reached 97%, which indicates it could be used to predict the shrinkage tendency.

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Precipitation and evolution of nodular graphite during solidification process of ductile iron

Cited by 14 publications

References 29 publications

Investigation on effect of carbon equivalent and inoculation on the solidification and shrinkage tendency of ductile cast iron using thermal analysis

Investigation on effect of carbon equivalent and inoculation on the solidification and shrinkage tendency of ductile cast iron using thermal analysis

implementation of cored wire technology into production of ductile iron for castings designated for extreme conditions

Mechanism of Shrinkage in Compacted Graphite Iron and Prediction of Shrinkage Tendency

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