SU1541272A1 - Method of inoculating grey iron - Google Patents

Abstract

The invention relates to foundry, in particular to the production of modified gray iron. The goal is to increase the strength and hardenability of cast iron. Low-alloyed scale steels are introduced into the melt in the amount of 2-5% of the mass of liquid iron, followed by modification with ferrosilicon and ferromanganese (or silicomanganese). 1 tab.

Description

The invention relates to foundry, in particular to the production of modified gray iron.

The purpose of the invention is to increase the strength and hardenability of cast iron.

Molten iron injected into forge scale low alloy steels in the amount of 2-5% by weight of the melt, and then a modified mixture consisting of 75% ferrosilicon and ferromanganese (silicomanganese).

The difference of the proposed method lies in the fact that the cast iron prior to the introduction of scale is prepared for subsequent modification. Blacksmith dross alloyed steel, introduced into the iron in the amount of 2-5%, reduces the content of silicon and carbon. Carbon reductions are also due to the addition of a carbon-free additive. Alloy elements, such as nickel, are reduced from the scale introduced into the liquid iron.

chromium, molybdenum. Oxidation of cast iron produces oxides, which, being embryos, contribute to its graphitization. Graphitization is enhanced by the subsequent introduction of ferrosilicon 75%. The introduction of blacksmith doped alloy steels of less than 2% does not sufficiently increase the mechanical tensile strength and depth of the hardened layer. Entering blacksmith dross over 5% already contributes to increasing the strength and hardenability. Ferrosilicon 75% has a graphitizing effect on cast iron, which can significantly reduce its bleaching. Ferromanganese contributes to the perlitization of cast iron, which has a positive effect on its strength and hardenability. Ferromanganese or silicomanganese manganese forms strong compounds with sulfur, which also contributes to graphitization.

Intensive modification serves to equalize the distribution of graphite.

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four

1C 1C

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plate in different sections of the casting. The reduction of carbon, silicon, the introduction of manganese makes it possible to obtain a pearlite structure, which has a positive effect on increasing the strength and hardenability of cast iron.

Comparative testing of cast iron modification according to the known and proposed methods has been carried out.

Note The original cast iron has the following chemical composition, wt.%: Carbon 3.49 {silicon 2.30; manganese 0.42; sulfur 0.05; phosphorus 0.09; chromium 0.26; nickel 0.30; copper 0.025; titanium 0.04.

The cast iron is melted in an induction crucible furnace, using as cast materials cast iron, steel scrap, ferroalloys, copper, and nickel. Cast iron is overheated to 1390 C.

For the modification of cast iron, blacksmith dross of low alloyed steels is used: ferromanganese, ferrosilicon, silicomanganese. amount

4J2724

modifier (delivers 0.8% by weight of the liquid metal.

The strength of the iron and the hardenability are determined. Hardening is performed from a temperature of 870 ° C to engine oil. The hardenability is determined by the depth of the hardened layer to a hardness of 40 HRC.

Data on the parameters of the method of modifying the cast iron, its strength and hardenability are given in the table;

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Claims (1)

DETAILED DESCRIPTION OF THE INVENTION A method for modifying gray iron, including smelting, overheating, and modifying with ferrosilicon and ferromanganese or silicomanganese, characterized in that, in order to increase the strength and hardenability of the iron, 2-5% low-alloy steel is added to the melt before modifying melt.  Discontinuities, utzhiny on samples.