Effect of graphite morphology on the tensile strength and thermal conductivity of cast iron

Liu, Yangzhen; Li, Yefei; Xing, Jiandong; Wang, S.G.; Zheng, Baochao; Dong, Tao; Li, Wei

doi:10.1016/j.matchar.2018.07.001

Cited by 45 publications

(20 citation statements)

References 33 publications

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“…The graphite morphology (shape, size, surface fraction, distribution, and nodularity), which depends strongly on the chemical composition, has a significant influence on the mechanical properties of ductile cast irons [26]. It is known that spheroidizing the melted iron with reactive elements such as magnesium, calcium, cerium, and other rare earth elements leads to nucleation and growth of spherical graphite and, as a result, ductility and toughness of cast iron increase.…”

Section: -Results and Discussion 3-1-graphite Morphologymentioning

confidence: 99%

Effects of aluminum and copper on the graphite morphology, microstructure, and compressive properties of ductile iron

Sazegaran

Teimoori

Rastegarian

et al. 2021

J min metall B Metall

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The effect of aluminum (0, 2, 4, and 6 wt. %) and copper (0, 2, 4, and 6 wt. %) are investigated on graphite morphology, microstructure and compressive behavior of ductile iron specimens manufactured by sand casting technique. The graphite morphology and microstructure are evaluated using optical microscopy (OM) and scanning electron microscopy (SEM) equipped image processing software. To study the mechanical properties, the compression test is conducted on the ductile iron specimens. The results indicate the surface fraction and nodule count of graphite decrease by increasing the amount of aluminum from 0 to 2 wt. % and then, increasing from 2 to 6 wt. %. In addition, the nodularity of graphite increases by the increment of the aluminum amounts. By adding the amount of copper, the surface fraction and nodule count of graphite increase and nodularity of graphite decreases. The addition of aluminum and copper decreases the surface fraction of ferrite and increases the surface fraction of pearlite in the microstructure. By increasing the amounts of aluminum and copper, compressive stress vs. strain curves are shifted upwards, and modulus of elasticity, yield strength, maximum compressive stress and fracture strain improve. In comparison with copper, aluminum has a greater influence on the mechanical properties of ductile iron.

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Section: -Results and Discussion 3-1-graphite Morphologymentioning

confidence: 99%

Effects of aluminum and copper on the graphite morphology, microstructure, and compressive properties of ductile iron

Sazegaran

Teimoori

Rastegarian

et al. 2021

J min metall B Metall

View full text Add to dashboard Cite

show abstract

“…It can be flexibly applied to cast irons with various graphite morphologies and microstructures [14] . Therefore, it has been widely used in recent years [38][39][40]84] . However, interconnected structures with lamellar and compacted graphite are not considered in these models, and the results are independent of graphite size.…”

Section: Discussionmentioning

confidence: 99%

Thermal conductivity of cast iron -A review

Wang

2020

China Foundry

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C ast irons are among the most widely used metallic materials due to their good mechanical and physical properties, excellent casting ability and low cost. According to the survey of Modern Casting [1] , as shown in Fig. 1, outputs of lamellar graphite cast iron (LGI) are much higher than that of spheroidal graphite cast iron (SGI) though SGI has better mechanical properties. One of the reasons is that LGI has wide applications at high temperatures due to its superior thermal conductivity. That's why the LGI and compacted graphite cast iron (CGI) are widely applied in brake disc, engine block and cylinder head [2][3][4][5] . The thermal conductivity is an extremely important performance index for cast irons. The high thermal conductivity can help to transfer heat rapidly and prevent thermo-mechanical fatigue, deformation and hot cracking, thereby ensuring the applications of cast irons in more complex or harsher conditions and improving the service life of products [6] . Therefore, on the premise of basic mechanical properties, the design and development of high thermal conductivity cast irons is one of the key points in the research and development of cast irons.Cast irons are multi-component alloys with regular elements of C and Si and some commonly added alloying elements, such as Mn, Cu, Ni, Cr, W, Mo, V, Ti, Al, etc. The microstructure of cast irons is complicated, usually composed of ferrite, pearlite, graphite, and cementite. So, the thermal conductivity of cast irons is dependent on both the alloying elements and structural constituents.During solidification, the formation of cast iron microstructure, especially the graphite morphology, is governed by the difference in thermal conductivity between graphite and austenite in eutectic couple, and between different orientations of graphite crystals [7] . According to different graphite morphologies, cast irons where carbon precipitated in the form of graphite (graphite cast irons) are mainly divided into LGI with lamellar graphite, CGI with compacted graphite and SGI with spheroidal graphite. Generally, the thermal

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“…Although the mechanical properties are significantly improved by optimizing the matrix microstructure, the morphology of the graphite also has a significant effect on the microstructure and mechanical properties of ductile iron . The wear loss in dry conditions is increased, and the fatigue strength in wet conditions is significantly decreased with the decrease in spheroidization rate of graphite .…”

Section: Introductionmentioning

confidence: 99%

Influence of Graphite Nodules on the Microstructure and Mechanical Properties of Hollow Ductile Iron Pipe after Austempering Treatment

Wang

Gao

et al. 2019

steel research int.

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Herein, the microstructure and mechanical properties of ductile iron with different numbers of graphite nodules before and after austempering treatment are systematically investigated. The results show that the amounts of graphite nodules affect the microstructure and resulting mechanical properties of ductile iron. The ferrite fraction in an as-cast matrix decreases with the increase in graphite nodules; this outcome is mainly attributed to the cooling rate. The matrix of ductile iron after austempering treatment is composed of acicular ferrite and retained austenite. The acicular ferrite is refined with the increase in graphite nodules, because the increase in interface between graphite/austenite provides more nucleation sites during austempering treatment. Meanwhile, the formation of ferrite causes carbon atoms to diffuse into the surrounding matrix, giving rise to the increase in carbon concentration of untransformed austenite and further stabilizing the retained austenite. Hence, the volume fraction of retained austenite and the carbon content in it both increase with the increase in graphite nodules. The amounts in graphite nodules affect the mechanical properties significantly after austempering treatment; this outcome is related to the phase constituents of ductile iron after austempering treatment. Herein, the detailed mechanisms are discussed.

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Effect of graphite morphology on the tensile strength and thermal conductivity of cast iron

Cited by 45 publications

References 33 publications

Effects of aluminum and copper on the graphite morphology, microstructure, and compressive properties of ductile iron

Effects of aluminum and copper on the graphite morphology, microstructure, and compressive properties of ductile iron

Thermal conductivity of cast iron -A review

Influence of Graphite Nodules on the Microstructure and Mechanical Properties of Hollow Ductile Iron Pipe after Austempering Treatment

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