SU1548213A1 - Composition for inoculating iron - Google Patents

Abstract

The invention relates to foundry, in particular, to modifiers for gray iron with lamellar graphite, melted in cupolas and electric furnaces. The purpose of the invention is to reduce chill and increase the duration of the modifying effect. The mixture for the modification of cast iron contains, in wt.%: Ferrosilicochrome 40-65

silicomanganese 20-45

waste electrode production 10-20. The use of the mixture allows a 20-25% reduction in the bleachability of cast iron and an increase in the duration of the modifying effect by more than 10 minutes. 2 tab.

Description

The invention relates to foundry, in particular, to modifiers for gray iron with lamellar graphite, melted in cupolas and electric furnaces.

The aim of the invention is to reduce chill and increase the duration of the effect of the modifying effect.

The proposed mixture for modifying cast iron contains ferrosilicomer, silicomanganese, and electrode production waste in the following ratio of components, May .:

ferrosilicochrome 40-65

Silikomanganese 20-45

Electrode waste

production10-20

The proposed mixture is prepared from crushed or granulated components, with the ferrosilicochrome and silicomanganese fraction having to be 2-20 mm 3 depending on the metal capacity of the ladle, electrode production waste - in the form of powder with a fraction of 0.2-1 mm, which ensures the most effective absorption in the molten iron .

Granulated ferrosilicochrome PSC20 and PSC26 are used to introduce chromium and silicon into the original cast iron, which has a dual effect: graphitizing and carbide forming. When less than 40 wt.% Of ferrosilicochromium is introduced into the mixture, an insufficient amount of chromium passes into the cast iron and this has little effect on the improvement of the iron quasi-isotropy and strength properties. Increasing the content of ferrosilicochrome (more than 65 May.%}

315

leads to an increase in chill and decrease in the strength properties of cast iron.

-. The content in the mixture of silicomanganese within the mass% fulfills a double role: as one of the active perlisers, manganese contributes to the improvement of the mechanical properties of cast iron, as well as improving the absorption and distribution of graphite in the pg alloy of cast iron.

The upper limit of the content of silicomanganese in the mixture is determined by the effect of manganese to interfere with graphite formation, which entails an increase in the tendency to chill iron in thin sections of castings. The lower limit is determined by the ability of the silico-manganese to affect the strength properties of the iron.

Waste electrode production is introduced into the mixture to reduce chill, increase the duration of the effect of modification and improve the distribution of inclusions of graphite.

The positive effect of graphite on the microstructure and properties of cast iron begins to manifest itself when the mixture contains more than 10% by weight of graphite production waste.

An increase in their content in the mixture (more than 20 wt.%) Leads to an increase in the size of graphite inclusions in the iron structure and a decrease in its mechanical properties.

For experimental verification of the proposed composition, a test is performed. The iron melting is carried out in a high-frequency induction furnace with an acid stuffed lining with a capacity of 60 kg. Foundry and pig iron, waste carbon steel and cast iron scrap are used as starting materials. After melting the charge materials, the molten iron in the furnace is superheated to 1450 ° C and held for 5-10 minutes.

The effectiveness of the cast iron modification by the known and proposed mixtures is determined by the amount of chill in the fracture of a wedge sample cast in a sandy-clay mold cooled on one side by a massive cooler, as well as the mechanical properties of the cast iron. Modification (the addition value of the mixture is 0.8%) and the aging of the iron are carried out in a crucible of an induction furnace at 13 ° -1380 ° C. Modify cast iron containing, in wt.%: Carbon 3.0-3.2;

five

0

five

Q

0

five

0

five

0

five

silicon 1.5-1.6; manganese 0.6-0.8; phosphorus 0.95-0.1; sulfur 0.05-0.1.

The selection of liquid iron for casting is done after 5 minutes.

The composition of the approved modifiers, the amount of chillings and the duration of the effect of modification are given in Table. 1-2.

As can be seen from the test results, the known mixture (compounds 1 and 2) has a higher whitening ability, and the survivability of the modifying effect is no more than 5 minutes. The proposed mixture (compositions -6, 9, Yu, 13, with a ratio of components within the proposed limits, has a lower bleaching ability by 20-25%, the survivability of the modifying effect is more than 15 minutes, but the mechanical properties of cast iron increase: strength by 10- 15% and hardness 5-10%.

Introduction to the composition of the proposed mixture of graphite waste less than 10 wt.% (Composition 12) reduces the duration of the effect of modification. Introduction of a mixture of ferrosilicon-chromium and silicomanganese below the recommended limits (composition 3, 8) reduces the strength and duration of the effect of modification.

The introduction of silicomanganese and ferrosilicochrome above the recommended limits (compounds 7, 11) leads to an increase in bleachability.

When using the proposed mixture, the duration of the effect of modification is increased, the chill is reduced by 20-25% and the cost of the mixture decreases due to the use of silico-manganese.

Claims (1)

Invention Formula The mixture for modifying the cast iron, containing ferrosilicochrome and manganese-containing component, is different from that in order to reduce chill and increase the duration of the modifying effect, it additionally contains electrode production wastes, and as manganese-containing component is manganese in the following ratio of components , wt.%: Ferrosilicochrome 0-65 Silica manganese Electrode waste production10-20 Table 1 table 2 zo -330 320 290 250 245 225 eight Iy--. Continuation of table 2 19 13 11 11 20 15 eleven 11.5 21 15 11 12 21 16 12 13