Mechanization of electric melting furnace operations

The power density in glass melts has been studied at different arrangements of electrodes in all-electric melting furnace. Bottom, top and plate electrodes have been arranged into the model furnace in form of hexahedron about the edge 1m. The results of mathematical modelling showed that there has been very narrow relationship between the distribution of power density in glass melt and the temperature field and therefore by means of suitable arrangement of electrodes it is possible to influence the intensity of convective currents of the glass melt. From evaluated dependencies of power density distribution near the tips of electrodes follows that in case of rod electrodes, the power density decreases with increasing length of the electrodes. Opposite behaviour happens at plate electrodes because the power density distribution in the centre of the basin between electrodes increases with increasing distance of the electrodes from the bottom of the furnace. By means of mathematical modelling also have been evaluated the volumes of glass melt in surroundings of electrodes where are the power densities superior to pmean (60000 W.m-3). The volumes are very small with regard on the total volume of furnace and do not exceed the value 22%. From mentioned follows that mathematical modelling of glass melting furnaces by means of CFD programme Fluent gives to acceptable computational subservience to study of power density distribution in all-electric melting furnaces.

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Recycling of Steel AISI 52100 Gotten by the Route of Powder Metallurgy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.805.325 ◽

2014 ◽

Vol 805 ◽

pp. 325-330

Author(s):

Wellington S. Diogo ◽

Dalton G.B. de Souza ◽

Rayana F. Rodrigues Lourenço ◽

M.L.M. Noronha Melo ◽

Kátia R. Cardoso ◽

...

Keyword(s):

Powder Metallurgy ◽

Crystallite Size ◽

Melting Furnace ◽

High Energy ◽

Electric Melting ◽

Ball Bearings ◽

Powder Morphology ◽

Cold Forming ◽

Aisi 52100 ◽

Aisi 52100 Steel

The AISI 52100 steel is a material widely used in the industry due to its high fatigue resistance, dimensional stability, high hardness and wear resistance. This steel is used for production of ball bearings, stamping tools, etc. In case of production of ball bearings and its track this material is spherodized because, due to its high content of carbon, about 1%, it has high mechanical strength making it impossible to cold forming. To obtain a wear resistant surface, after forming, this material is hardened and tempered. Normally to obtain the AISI 52100 steel, arc electric melting furnace is used. This work aims the reuse of AISI 52100 steel by powder metallurgy route, starting from the machined chips using high energy mill (planetary) to obtain the powder. Then, the powder was uniaxially pressed into a press with a load of 4 tons, to form the specimen, later on pressed in an isostatic press at a pressure of 300MPa to obtain a better densification. To analyze the powder morphology and the phases obtained after sintering, was used a scanning electron microscope and X-ray diffraction to calculate the crystallite size. It was verified that with more than 10 hours of grinding, the crystallite size does not change significantly, the particles gained rounded shapes with a size distribution between 30 and 5μm. The microstructure obtained by the two routes was nearly identical after sintering.

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Thermal Expansion Behavior of Alloyed Pearlitic Flake Graphite Cast Irons

Journal of Engineering Materials and Technology ◽

10.1115/1.3225895 ◽

1986 ◽

Vol 108 (4) ◽

pp. 358-364

Author(s):

M. C. Rukadikar ◽

G. P. Reddy

Keyword(s):

Thermal Expansion ◽

Coefficient Of Thermal Expansion ◽

Melting Furnace ◽

Steel Scrap ◽

Electric Melting ◽

Flake Graphite ◽

Cast Irons ◽

Thermal Expansion Behavior ◽

Expansion Behavior ◽

Nickel Copper

Precise understanding of thermal expansion behavior of flake graphite cast irons is essential to know the thermal fatigue resistance of these irons when used for elevated temperature application like diesel engine components, ingot moulds, hot mill rolls, glass moulds, dies, etc. Twenty-three pearlitic flake graphite irons having identical base compositions (levels of sulfur, manganese, phosphorus, dissolved gases, and trace elements) having two levels of carbon (3.93 percent and 3.00 percent) and alloyed with elements such as molybdenum, vanadium, chromium, tin, nickel, copper, antimony, and aluminum were produced by carburizing steel scrap in an electric melting furnace. Thermal expansion behavior of all these irons were studied with the help of a dilatometer to determine the influence of graphite morphology and chemical composition. It is seen from the results that thermal contraction of flake graphite irons follows a different path during cooling than the thermal expansion path followed during heating. Further increase in graphitic carbon and coarseness of graphite tend to lower the coefficient of thermal expansion. Additions like molybdenum/copper at high level help in reducing thermal expansion; higher content of tin/antimony/aluminum/silicon tend to increase it while chromium/nickel/copper at low level have no effect. The present investigation has thus provided information regarding thermal expansion/contraction behavior of twenty-three flake graphite irons having almost all commonly used alloying elements.

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