SU1696557A1 - Modifier for high-strength cast iron preparation - Google Patents

Abstract

FIELD OF THE INVENTION The invention relates to linear production and can be used for the production of nodular cast iron. The purpose of the invention is to improve the crushability, decrease the melting temperature of the modifier, as well as reduce the hardness of cast iron and increase its ductility. The modifier contains May%: magnesium 25-80; REM 1-15; aluminum - the rest. The increased magnesium content in the proposed modifier provides a low melting point (t = 435-455 ° C). 1 tab

Description

The invention relates to metallurgy and foundry, in particular to modifier ligatures for the production of nodular cast iron.

The purpose of the invention is to improve the crushability, decrease the melting temperature of the modifier, as well as reduce the hardness of cast iron and increase its plasticity.

The goal is achieved by the fact that the modifier containing magnesium, rare earth metals and aluminum contains components in the following ratio, wt%: magnesium 25-80; rare earth metals 1-15; aluminum - the rest.

When the content of magnesium is less than 25% and more than 80%, the modifier is poorly crushed into fractions necessary for dosing when modifying the cast iron and a sufficiently high assimilation of the components of the modifier. Magnesium combined with aluminum in

selected limits ensures good crushability of the modifier and the lowest melting temperature (450 ° C), which is a positive factor in the processing of low temperature liquid cast irons

The content of rare-earth metals less than 1% does not ensure the neutralization of aluminum as an element of antiglobulizer when modifying cast iron, which causes the production of lamellar graphite and a decrease in the mechanical properties of cast iron. The content of rare-earth metals in the modifier above 15% causes stabilization of perlite and the appearance of cementite in the structure of high-strength cast iron, which reduces ductility, increases hardness and impairs the machining of cast iron.

Apyuminium within the specified limits helps to obtain low-melting modoSo

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fixer and when entering into the iron acts as a graphitizing element.

For the experimental verification of the proposed composition and a comparative analysis with a known modifier, eight modifier compositions were prepared, three of which corresponded to the known, three to the proposed composition and two to those outside the interval specified in the proposed composition.

The modifier was smelted in graphite crucibles, which were installed in the working space of the electric furnace of the CH3-3 x 8 x 2/10 resistivity. Technically pure aluminum and magnesium, as well as mischmetall (alloy of rare-earth metals) were used as charge materials. The resulting modifier was crushed into fractions of 2-10 mm.

Cast iron composition: carbon 3.2-3.4; silicon 2.0-2.2; manganese 0.3-0.5, sulfur 0.02; phosphorus 0.05 was melted in an ICT-0.16 induction furnace with a quartz lining. High-strength cast iron was produced by the in-mold modification method. Cast iron before pouring into molds was treated with FS-75 ferrosilicon in an amount up to 1% by weight of the liquid metal. The consumption of the modifier during in-house modification was constant in all experiments — 0.2% of the weight of the cast iron poured into the mold. The temperature of the cast iron during casting was in the range of 1300-1360 ° C. Samples were cut from the finished casting to determine hardness, tensile strength and elongation, as well as samples for microstructural analysis.

The test results and analyzes of the modifier and cast iron samples are presented in the table.

From the table it follows that the proposed modifier (compounds 4-6) to obtain

High-strength cast iron has significantly lower melting points (435-455 ° C) and crush strength limits (2.0–18 kg / mm), which accordingly provides for better absorption when processing low-temperature liquid cast irons and crush to fractions. The presence of ferritic base in the structure of cast iron, treated with the modifier of the proposed composition, without

structural-free cement and ledeburite provides a significant increase in mechanical properties - elongation to 16-18% with a tensile strength of 40-42 kg / mm2 and hardness of 160-170 HB,

which allows you to improve the machinability of cast iron.

The use of the proposed invention will reduce energy costs and labor costs in the manufacture of master alloy,

significantly reduce the consumption of ligatures during the modification, reduce energy costs and lining materials in the smelting of iron due to the lower temperature of the liquid iron required

when modifying, and also to reduce the consumption of tools during the machining of castings and to improve the physical and mechanical properties of the processed iron.

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Claims (1)

Invention Formula The modifier for producing high-strength cast iron containing magnesium, rare earth metals and aluminum, is due to the fact that, in order to improve crushability, lower the melting temperature of the modifier, as well as reduce the hardness and increase the ductility of the cast iron, it contains the following ratio, wt.%: magnesium 25-80; rare earth metals 1-15; aluminum - the rest subject to 25.0 50.0 80.0 15.0 6.0  1.0 Else Else Else 1B, 0 2.0 16,0 16.0 16.0 16.0 1) 00 "about 1 (20 "5" About "5