SU1479544A1 - Inoculator of iron for castings - Google Patents

Abstract

FIELD OF THE INVENTION The invention relates to foundry, in particular, to cast iron modifier with lamellar graphite. The purpose of the invention is to increase the isotropy of the structure and mechanical properties of cast iron in differential castings. The cast iron modifier contains silicon-containing ferroalloy and graphitized electrode powder in the following ratio, wt.%: Powder of graphitized electrodes 20-40, silicon-containing ferroalloy 60-80, and in the composition of silicon-containing ferroalloy contains @ 3-4% wt. MG and 2-8 MAC .% REM. The addition of 3-4 wt.% MG and 2–8 wt.% REM into the silicon-containing ferroalloy and the use of graphite electrodes as a carbon-containing powder allows a 6–8-fold reduction in the hardness data of difference castings. The use of the invention is most expedient in the production of basic parts of machine tools with differential parts with massive portions of castings, to which increased demands are made on the structure and properties of cast iron, their stability and uniformity over the section of castings. 1 tab.

Description

and silicon-containing ferroalloy, additionally contains 3-4% by weight of magnesium and 2-8% of rare earth metals,

Using the modifier as a silicon-containing ferroalloy ferrosilicon with 3-4 wt.% Magnesium, 2-8 wt.% Of rare-earth metals allows

INCREASE IT MODIFIER EFFECT,

provides an improvement in the structure of the metal base of iron and graphite inclusions and their homogeneity over the cross section of iron and thick-walled castings.

With an increase in the content of ferro-silico-magnesium alloy from 2-8 wt.% Rare earth metals above 80 mass% and, consequently, with a decrease in the powder content of graphitized electrodes in the composition of the proposed modifier below 20 wt.%, The modifying effect, especially the graphitizing ability of the modifier, and the suggestiveness decrease its preservation, the chipping of the pig iron and the heterogeneity of the structure and properties of the metal over the cross section of differential castings due to the introduction of an insufficient amount of g tovyh germinal centers for the crystallization of graphite and an increased amount of magnesium and rare earth metals facilitate the formation of free cementite and structurally edge chill in the castings.

With a decrease in the content of ferro-silico-magnesium alloy from 2-8 wt.%

rare earth metals below 60mae,%

and, therefore, increasing the powder content of graphitized electrodes in the composition of the proposed modifier above 40 wt.% decreases the strength of the modified cast iron and increases the heterogeneity of the structure and properties of cast iron over the cross section of iron castings due to the introduction of excess carbon into the liquid cast iron, enlargement of graphite inclusions, deterioration of their shape and distribution, increasing the amount of graphite inclusions and ferritizing the metal base.

When using a ferrosilicon alloy with a concentration of rare-earth metals above 8 wt.% In the composition of the proposed modifier, the tendency of cast iron to

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five

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Bela, appears structurally free cementite, especially in thin sections and edges of the casting, which leads to an increase in the heterogeneity of the structure and properties of cast iron in the cross section of differential castings.

When using silicon-containing ferroalloy with a concentration of rare-earth metals below 2 wt.% In the composition of the proposed modifier, the heterogeneity of the structure and properties of cast iron in the cross section of differential castings increases due to the excessive graphitizing effect of the modifier: ferrite appears in the cast iron base and in that quantity more than thicker than the wall of the casting, the inclusions of graphite vary in size from 25 to 360 µm, their number increases, as a result of which the heterogeneity of the properties of the pig iron increases. about the cross section of castings.

The modifier for cast iron uses materials in the following form: powder of graphitized electrodes (TU 01-17-68) with particles less than 1 mm in size, a ferrosilicomagnetic alloy with 2-8 wt.% Rare earth metals FSMgZ and FSMg4 (TU 14- 5-134-86) with particles ranging in size from 1 to 2 mm.

The modifier for cast iron is prepared by weighing the calculated doses of the components in accordance with the proposed quantitative ratio and depending on the mass of the melt being processed.

The effectiveness of the modifier is detected on cast iron from 3.15 to 3.25 ° C, 1.70-1.88% Si; 0.45-0.52% MP; up to 0.1% P; to 0.08% S melted in an induction furnace and heated to 1450 ± 10 ° С, and then cooled to 1400 ° С. The modification is carried out in a stream or in a ladle when liquid iron is drained from the furnace with an additive modifier in an amount of 0.3% of the mass of liquid iron.

The table shows the compositions of the proposed and known modifiers and the properties of cast iron after it has been processed by the tested compounds.

The effectiveness of the proposed and known modifier compositions was evaluated: according to the tensile strength Gg and Gn bending of cylindrical specimens with a diameter of 30 mm and a length of 340 mm, by structural samples with a cross section of 10, 20, 40 and 60 core shape with a metal one, and for the duration of the preserve modifying effect.

The proposed iron modifier, as compared with the known, is characterized by a higher modifying effect, manifested in an increase in tensile strength by 16-25% and a uniform structure of the metal base and inclusions of graphite, a decrease in the hardness variation of iron over the cross-sectional and thick-walled castings (10-60 mm) about 6-8 times, and increasing the duration of the preservation of the modifying effect by 1.5-2.0 times, can be used in the production of a wide range of castings of parts with high operation ionic properties (strength, durability), as permits reliably obviate The relative Br in thin sections of castings and x inhibit ferritization thick sechesvoystva iron.

Claims (1)

Invention Formula The cast iron modifier for castings, including carbon-containing and silicon-containing materials, is due to the fact that, in order to increase the isotropy of the structure and mechanical properties of cast iron in remote castings, powder of graphitized electrodes, silicon-containing material is used as carbon-containing material. material - ferrous silicate alloy with REM in the following ratio of components, wt.%: Powder of graphitized electrodes 20-40 Ferro silico-magnesium alloy with RZM60-80 and Ferro-silico-magnesium alloy with REM, contains, wt%: Magnesium REM Silicon containing ferroalloy 3-4 2-8 Rest 6 (prototype) 33 67 250 14795448  Table continuation Editor T. Lazarenko Compiled by A. Barmykov Tehred M. Didyk Proof-reader I. Erdeyi Order 2507/27 Circulation 577 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 4/5, Moscow, Zh-35, Raushsk, Emb. 113035 “M - ta. ..- - - - ..-.-- “. Production and publishing plant Patent, Uzhgorod, st. Gagarin, 101 Subscription