SU1014957A1 - Cast iron - Google Patents

Abstract

CAST IRON containing carbon, silicon, manganese, nickel, magnesium. calcium, copper, rare earth metals, barium and iron, characterized in that, in order to stabilize the mechanical properties of the casting section, it contains components at the following ratio, wt.%: Carbon 3.2 - 3.6 Silicon 2.55- 3.7 0.45-0.9 Manganese 0.01-0.2 Nickel Magnesium 0.02-0.07 Calcium 0.005-0.05 Copper 0.05-0.25 Rare-earth 0.06-0.1 Metals 0,005-0,02 Barium Iron Else (L

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The invention relates to metallurgy, more specifically to the search for high-strength cast irons, and can be used in the production of precision differential castings with high strength and satisfactory plasticity with good machinability. Known cast iron. I of the following chemical composition, wt.%: Carbon 2-4.5 Silicon 1.5-3.8 Manganese 0.1-1.5 Chromium. 0.01-0.15 Nickel0.01-1.5 Magnesium 0.01-0.09 Calcium0.01-0.09 Barium0.001-0.08 Rare-Earth Metals0.001-0.15 Aluminum0.01-5.0 Iron Remaining B A disadvantage of the known cast iron is the low stability of the mechanical properties over the section of the casting. The closest to the proposed technical essence and the achieved result is cast iron 2 of the following chemical composition,. wt.%: Carbon 3.2-3-3 Silicon 2.55-3.2 Manganese 0.01-0.4 Magnesium 0.005-0.08 Calcium 0.005-0.05 Rare-earth metals 0.005-0.05 Nickel -0, 3-0.6 Copper0.3-0.6 Barium0.001-0.03 Chromium0.01-0.06 IronOstal The disadvantage of the known cast iron is the instability of the mechanical properties of the section of the castings. The purpose of the invention is to stabilize the mechanical properties of the casting section. This goal is achieved by the fact that cast iron containing carbon, silicon, manganese, nickel, magnesium, calcium, copper, rare earth metals, barium and iron contains components in the following ratio, wt%; Carbon3,2-3,6 Silicon2,55-3,7 Manganese0.45-0.9 Nickel0.01-0.2 Magnesium0.02-0.07 Calcium0.005-0.05 Copper0.05-0.25 Rare Earth metals. 0.06-0.1 Barium 0.005-0.02 IronOstal As an impurity, the proposed cast iron may contain: phosphorus up to 0.1, sulfur up to 0.08 and chromium up to 0.1 wt.%. Example. The cast iron is melted in 50 kg of an acid-lined induction furnace and, after melting, is superheated to. Cast iron LKZ, steel scrap, ferroalloys, copper, and nickel are used as charge materials. After overheating, the cast iron is adjusted according to the chemical composition of the melt in the furnace with the appropriate ferroalloys. Also, a preliminary ladle treatment of the melt with a mixture of ferroceri and ferrosilicobarium is carried out, followed by spheroidizing treatment of the melt with an LCM-type ligature in a mold. Then plates with a thickness of 30 mm are cast from which standard specimens are cut out for mechanical testing. The table shows the chemical composition and mechanical properties of the proposed cast iron in comparison with the known with different sulfur content. Magnesium provides nodular graphite and high mechanical properties. When the content of magnesium is less than 0.02%, inclusions of lamellar and vermicular graphite are observed in the structure even in low-sulfur iron (0.01-0.02% sulfur; the introduction of magnesium over 0.07% is irrational, as the shape of graphite worsens to chill (remodification effect), modifier consumption increases.The introduction of cerium group in the composition of the REM alloy in amounts of 0.06 0, 1% helps to obtain the correct spherical shape of graphite and stabilize the mechanical properties of cast iron in differential castings. stabilization of the cast iron properties with rare earth elements with significant fluctuations of the harmful sulfur impurity in the initial melt up to 0.08%. The lower limit of the content of REM The upper limit (0.1%) is limited by the increase in the tendency of pig iron to chill when the content of REM in the alloy is higher than 0.1%. To obtain a high alloy strength (compensation of a decrease in the concentration of Cu and Ni compared to the known composition) with sufficient ductility. the content of manganese In it is from 0.45 to 0.9%. The lower limit of the manganese content is due to the need to obtain sufficient strength. The upper limit (0.9% MP) is limited by an increase in the tendency of pig iron to chill and a decrease in ductility.

The concentration of silicon (2.5-3.5% contributes to the crystallization of the alloy according to a stable state diagram without structurally free carbides.

The lower limit for cremish (2.5% JI is set on the basis of the requirement to exclude chill in castings. Over the upper limit (3.5%), silicon somewhat deteriorates the spherical shape of graphite and reduces the plastic properties of the alloy.

Carbon in the range of 3.2-3.6% provides good casting and mechanical properties. The lower limit of carbon is 3.2% due to the need to exclude structural-free carbides in the alloy. Increasing the carbon concentration above 3.6% worsens the shape of graphite inclusions. Thus, a carbon concentration of 3.2–3.6% is optimal.

The calcium content (0.005-0.05%) in the alloy contributes to improving the shape of spherical graphite and increasing the purity of the melt in terms of impurities.

The optimum combination of increased strength and ductility of high-strength cast iron is achieved by alloying it with copper in the range of 0.05.

up to 0.25% and nickel - 0.01-0.2. Moreover, to increase the strength, copper and nickel should be selected on the upper limits, and to improve the plastic properties of the alloy, these components should be selected on the lower and middle limits. Thus, by varying the composition of the copper of copper and nankel in the cast iron, it is possible to obtain a spectrum of mechanical properties.

The content of barium in the alloy in concentrations of 0.005-0.02 contributes to the crystallization of cast iron according to a stable diagram without structurally free cementite. Exceeding this limit of barium content is uneconomical, due to its low growth effective; his action.

Concentration of harmful impurities in amounts of sulfur up to 0.08 and phosphorus up to 0.1% was established based on the need to provide spherical shape of graphite and to obtain high and uniform mechanical properties in complex differential castings during cupola iron smelting.

The structure of the proposed iron has a ferritic-pearlitic metal matrix and compact spherical inclusions of graphite.

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increases in the iron content of sulfur, and known. Thus, offering

being a harmful impurity, the pig iron is more resistant to mechanical properties due to unavoidable fluctuations, and their dispersion over the cross section of sulfur in it. The expected economic casting is reduced. The strength of the cue effect will be 50 thousand rubles a year.

Claims (2)

PIG IRON containing carbon, silicon, manganese, nickel, magnesium, calcium, copper, rare earth metals, barium and iron, characterized in that, in order to stabilize the mechanical properties over the cross section of the casting, it contains components in the following ratio, wt.%: Carbon Silicon Manganese Nickel Magnesium Calcium Copper Rare Earth 3.2 - 3.6 2,55-3,7 0.45-0.9 0.01-0.2 0.02-0.07 0.005-0.05 0.05-0.25 metals 0.06-0.1 Barium 0.005-0.02 Iron Else