SU1255272A1 - Method of producing elongated thick-wall cast iron castings - Google Patents

Description

The invention relates to the production of cast iron long items.

The purpose of the invention is to obtain equal Honpo4tibix in length and with increased strength of surface layers of cast iron-modified castings, preferably long-length.

The equal strength of a lengthy casting, on the order of two meters or more, is achieved by the fact that after the introduction of the modifying additive, the entire quarter length of the rotating mold is additionally introduced

ten

700 kg. Casting wall thickness 50 mm. Cast iron of the following chemical composition,%: C 3.5-3.8; Si 2.4-3.0; Mp 0.7-1.0; Si 0.5-0.7; Ni 0.4-0.9; AT 0.6-0.8.

A 5% dry pig iron chip is introduced into the rotary mold using a sandbox. Then a modifying additive of 0.5% by weight of the melt is introduced uniformly along the entire length of the mold. The ratio of magnesium to silicon in the additive is 1: 2. After completion of the casting, a flux consisting of a fluorite material, sodium silicate and low-melting magnesium-containing additives of boric acid is blown into the internal surface of the casting. The depth was obtained in the amount of 0.1–0.15% of the mass of the surface layer with graphite of spheroidal cast iron melt. At the same time, the ideal shape is 10 mm. The average ratio of the amount of low-melting modulus of ring strength is 458 MPa. the amount of magnesium-containing additive to the Brinell-modifying additive hardness is 20 from the outer layers to the inner ones 0.125-0.2. Introduction of modifying cuts 10mm: 190; 190; 160; 140; 160. Additives containing spheroidizing and graphitizing elements make it possible to form spheroidal graphite on the surface of the casting and thereby increase the strength of the surface layers. The ratio of the amount of magnesium to the amount of silicon in the modifying additive is 0.5-1.0, depending on the required thickness of the iron layer on the surface of the casting with. spheroidal graphite. The modifying additive is introduced in an amount of 0.5-1.25% by weight of the melt.

Before the introduction of additives.

A dry layer of dry iron chips to stabilize the effect of modification to form spheroidal graphite inclusions. The amount of iron chips is introduced up to 5% by weight of the melt.

The application of the proposed method in an amount of 0.3% at a ratio allows forming in a transverse amount of magnesium to silicon 1: 4; after lengthy castings, it structures the formation of a spheroidal py with differentiated mechanical graphite in a layer 2-3 mm thick.

A modifying additive of 0.750% by weight of the melt is introduced. The ratio of magnesium to silicon is 25 lt 1: 1.33. Received graphite

inclusions of spheroidal shape to a depth of 25-30 mm. The average module is 620-768 MPa. Hardness distribution: 240; 240; 180; 200

thirty

Introduce modifying additive

in the amount of 1.25% by weight of the melt when the ratio of the amount of magnesium to silicon is 1: 1. Spheroidal graphite

„.. ... inclusions extend to gLubin

the surface forms form insulation to 35-45 mm. The remaining thickness of the sections

have vermicular and lamellar graphite. The average modulus is 881-887 MPa. The hardness from the surface to the depth of the casting is: 240; 250; 240; 245; 180.

The use of properties modifying the added by changing the shape of graphite inclusions. Spheroidal graphite is formed in the structure of the outer surface layers. Vermicular forms in the deeper layers, and lamellar graphite on the inner layers.

Example. Used factory fittings produce a roller body with a mass

VNIIPI Order 4749/11 Circulation 757

Production polygr pr-tie, Uzhgorod, st. Project, 4

The average modulus is 336-340 MPa. Hardness throughout the section 137-140 HB. When a modifying additive is introduced in an amount of 1.5% by weight of the melt and the ratio of magnesium to silicon is 5: 4, spheroidal graphite is formed over the entire thickness of the casting. The average module is 1130-1120 MPa. Hardness 285-300 HB.

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Claims (4)

1. METHOD FOR PRODUCING LONG-DIMENSIONAL THICK-WALL CAST IRON CASTINGS, mainly from alloys close to eutectic, comprising introducing a modifying additive throughout the entire length of the casting mold and pouring the melt, characterized in that, in order to obtain modified castings of equal strength along the length, after the modifying additive is introduced along the entire length of the mold to the last quarter of the length, fusible magnesium-containing additives are additionally added in an amount of 0.1 - 0.15% of the mass of the melt being poured with the ratio of the number of light Avka magnesium-containing additives to the amount of modifying additives 0.125-0.2. 2. The method of pop. 1, it is important that, in order to increase the surface strength of iron castings due to the formation of spheroidal graphite, a modifying additive is introduced into the form in the form of a mixture of ligatures containing, in addition to spheroidizing elements, graphitizing with respect to the total amount magnesium to silicon 0.5-1.0. 3. The method according to PP. 1 and 2, which consists in the fact that a modifying additive is introduced into the form in an amount of 0.5-1.25% by weight of the melt. 4. The method according to PP. 1 to 3, characterized in that on the surface of the mold before the introduction of additives, an insulating layer of dry cast iron shavings is formed.