Effect of Cooling Rate on Microstructure and Mechanical Properties of Thin-Walled Ductile Iron Castings

Górny, M.; Tyrała, E.

doi:10.1007/s11665-012-0233-0

Cited by 71 publications

(53 citation statements)

References 2 publications

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“…The cooling rate increased from the center to the edge. Therefore, the amount of the graphite balls gradually increased with an increase in the cooling rate [21][22][23] . The Research & Development CHINA FOUNDRY morphology and quantity of the carbides were also related to the cooling rate.…”

Section: Effect Of Cooling Rate On the Formation Of Spheroidal Carbidementioning

confidence: 99%

Formation mechanism of spheroidal carbide in ultra-low carbon ductile cast iron

Shen

et al. 2016

China Foundry

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Male, born in 1957, Ph.D., Professor. His research interests mainly focus on the new type of abrasive materials such as ADI, CADI and their forming technology, the development of the iron melt quality online measurement and control system. A ustempered ductile iron (ADI) as a kind of very promising engineering material, is extensively used in gears, heavy machinery and transportation industries due to the combination of superior properties, such as high strength with good ductility, good wear resistance and fatigue tolerance [1][2][3][4] . The microstructure of the ADI consists of a certain number of graphite nodules, and the coarse graphite nodules with a strong fragmentation effect on the matrix structures seriously damage the properties of the materials [5,6] . Therefore, people try to obtain tiny, round and uniformly distributed graphite nodules to improve the mechanical properties by reducing the carbon content, and extensive efforts have been devoted to investigating ultra-low carbon ADI [7] .The ultra-low carbon ADI can be prepared with a certain composition of ductile iron through austempering heat treatment [8] , so an important step in the development of the ultra-low carbon ADI involves melting and casting of ultra-low carbon ductile irons. In the traditional Fe-C binary phase diagram, the right to the point (2.1wt.%) is called iron, and the left is called steel. However, the Abstract: The formation mechanism of the spheroidal carbide in the ultra-low carbon ductile cast iron fabricated by the metal mold casting technique was systematically investigated. The results demonstrated that the spheroidal carbide belonged to eutectic carbide and crystallized in the isolated eutectic liquid phase area. The formation process of the spheroidal carbide was related to the contact and the intersection between the primary dendrite and the secondary dendrite of austenite. The oxides of magnesium, rare earths and other elements can act as heterogeneous nucleation sites for the spheroidal carbide. It was also found that the amount of the spheroidal carbide would increase with an increase in carbon content. The cooling rate has an important influence on the spheroidal carbide under the same chemical composition condition.

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Section: Effect Of Cooling Rate On the Formation Of Spheroidal Carbidementioning

confidence: 99%

Formation mechanism of spheroidal carbide in ultra-low carbon ductile cast iron

Shen

et al. 2016

China Foundry

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“…Moulding materials with a low ability to absorb heat (e.g., LDASC sand) have a significant effect in reducing the cooling rates. 24,25) Attention should be paid to when LDASC sand is used as casting moulds (heat accumulation is equal a≈0.025 J/(°C·cm )), the cooling rates at the beginning of solidification decrease from about 29.1 K/s to 5.8 K/s.…”

Section: Thermal Analysismentioning

confidence: 99%

Thermal Conductivity of Thin Walled Compacted Graphite Iron Castings

et al. 2015

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This study addresses the effect of the cooling rate and of titanium additions on the exhibited microstructure and thermophysical parameters of thin-walled compacted graphite iron (TWCI) castings as determined by changing the moulding materials (silica sand and insulating sand LDASC), and Ferro Titanium. The research was conducted for thin-walled iron castings with a 3-mm wall thickness. The tested material represents the occurrence of graphite in the shape of nodules, flakes (C and D types, according to ISO Standard) and compacted graphite with a different shape factor and percent of nodularity. Thermal conductivity has been evaluated by the laser flash technique in a temperature range of 22-600°C. The results show that the cooling rates together with the titanium content largely influence the microstructure, graphite morphology and finally thermal conductivity of thin walled castings. Finally mechanism for thermal conductivity profile as a function of temperature for thin wall castings with different graphite morphology is provided.

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“…Characteristic features of thin-walled castings are also significant changes of cooling rate during insignificant wall thickness variation. The thermal analysis [12] shows that the change in wall thickness from 5 to 3 mm results in a significant increase in the cooling rate. This causes shortening of the solidification time and the risk of chill occurrence in cast iron.…”

Section: Microstructurementioning

confidence: 99%

“…The cooling rate of a casting is primarily a function of its section size, pouring temperature, and the ability of the material mold to absorb the heat. The process of obtaining thin-walled castings is not simple, because it is associated with a wide range of cooling rates at the beginning of graphite eutectic solidification [11,12]. With increasing cooling rates in thin-walled VGCI castings, thermal undercooling increases and graphite gradually becomes nodular, resulting in an increased nodule count and lower vermicular graphite ratio.…”

Section: Introductionmentioning

confidence: 99%

Role of Titanium in Thin Wall Vermicular Graphite Iron Castings Production

Górny

Kawalec

2013

Archives of Foundry Engineering

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In this paper the effects of titanium addition in an amount up to 0.13 wt.% have been investigated to determine their effect on the microstructure and mechanical properties of Thin Wall Vermicular Graphite Iron Castings (TWVGI). The study was performed for thinwalled iron castings with 3-5 mm wall thickness and for the reference casting with 13 mm. Microstructural changes were evaluated by analyzing quantitative data sets obtained by image analyzer and also using scanning electron microscope (SEM). Metallographic examinations show that in thin-walled castings there is a significant impact of titanium addition to vermicular graphite formation. Thinwalled castings with vermicular graphite have a homogeneous structure, free of chills, and good mechanical properties. It may predispose them as a potential use as substitutes for aluminum alloy castings in diverse applications.

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Effect of Cooling Rate on Microstructure and Mechanical Properties of Thin-Walled Ductile Iron Castings

Cited by 71 publications

References 2 publications

Formation mechanism of spheroidal carbide in ultra-low carbon ductile cast iron

Formation mechanism of spheroidal carbide in ultra-low carbon ductile cast iron

Thermal Conductivity of Thin Walled Compacted Graphite Iron Castings

Role of Titanium in Thin Wall Vermicular Graphite Iron Castings Production

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