SU1488340A1 - Innoculating composition - Google Patents

Description

The invention relates to metallurgy and can be used in the production of iron castings in metal forms. The purpose of the invention is to improve the mechanical properties of cast iron in castings. The proposed modifier contains May. 2: 8Ϊ 50-65,

Me 2.1-3.4., Ba 0.5-5.0, A1 0.5-5.0,

Ca 0.5–5.0, REM 0.5–8.0, B 0.05–0.4, and Pe are the rest. · Additional input into the composition of the modifier B and an increase in the Mg content from 0.12, 0 to 2.1-3.4 May. 2 provided increasing <about _in (MPa) and ductility 1,2-1,36 times with 0.1 5,7-7,82. about

The invention relates to metallurgy, in particular to the development of compositions of modifiers for the manufacture of castings in metal forms.

The purpose of the invention is to improve the mechanical properties of cast iron in castings.

The choice of the boundary limits of the content of components in the composition of the modifier is determined as follows. Within the recommended limits of boron, its effect is expressed in the effect of graphitization (at the lower level). With a further increase in the amount of boron in the modifier, a known carbide-stabilizing effect of this element is manifested: the amount of cementite increases in the structure of cast iron, the amount of graphite inclusions decreases. Possessing a high affinity for oxygen and nitrogen, these elements bind them and create conditions for the dissolution of all boron in iron.

The minimum limits of the concentrations of barium, calcium, aluminum, and rare-earth metals are due to the almost discovered effect of their action.

The maximum concentrations of these components are determined by their necessary and sufficient quantity to bind impurities in the iron (sulfur, oxygen, nitrogen) and to ensure the effective action of magnesium and boron. An increase in the mass fraction of A1, Ca, Ba above the upper limits leads to slagging00

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1488340

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modifier during the processing of liquid iron. The amount of rare-earth metals in the motor over 8% leads to the bleaching of pig iron. $

The lower and upper limits of the magnesium content ensure stable production of spherical graphite without pyroelectric effect and smoke emissions.

! The silicon content in the range of 50-65% corresponds to the optimum conditions of the technology for producing an alloy.

When the silicon content is below 50%, the solubility of alkaline-earth, rare-earth metals and magnesium falls and 15 it becomes impossible to obtain a modifier with a given content of these metals.

The concentration of silicon in the alloy over 65% reduces the density of the alloy and 20 worsens its solubility in the iron.

Thus, the proposed composition of the modifier has new properties that make it possible to effectively produce high-strength cast iron with enhanced mechanical characteristics under conditions of rapid cooling of castings.

Example. Modifiers were obtained by silicothermic reduction of the charge components in an electric arc furnace.

The chemical compositions of the known and proposed modifiers for iron castings are given in table. one.

Made modifiers introduced 55 in the iron in the amount of 1.3% by weight of the metal. The composition of the initial cast iron was as follows: 36% C, 1.8% 8ί, 0.64% Mn, 0.10% P, 0.03% 3. The chemical composition of the cast iron after modification was monitored, the amount of cementite, the amount and form of graphite inclusions, mechanical properties.

Modification was carried out in a ladle with an additive of the modifier to the bottom before pouring iron, followed by pouring into metal molds.

The temperature of the cast iron during the modification was 1400 ° C. The cooling rate of the cast iron is 20 degrees / s.

The results of processing modifiers known and proposed compositions in the manufacture of iron castings are given in table. 2

Experimental data show that the use of a modifier of the proposed composition allows to obtain in conditions of increased cooling rate of castings <nodular cast iron with high mechanical properties: increased tensile strength 1.20-1.36 times and improved from 0.1 to 5, 1-7.8% ductility.

Claims (1)

Claim The modifier is mainly for cast iron castings obtained at high cooling rates, containing silicon, magnesium, barium, aluminum, calcium, rare earth elements and iron, characterized in that, in order to improve the mechanical properties of cast iron in castings, it additionally contains boron in the following ratio components, May. %: Silicon 50-65 Magnesium 2.1-3.4 Barium 0.5-5.0 Aluminum 0.5-5.0 Calcium 0.5-5.0 Rarely landable metals 0.5-8.0 Boron 0.05-0.4 Iron Rest Table 1 The composition of the modifier Contents of elements, May. % Mg | Va [sa A1 | Tx | REM | 8Ϊ ¹ H Re Famous 1.1 2.3 2.4 2.0 7.2 2.5 66.2 2.2 Rest Proposed 1 2.1 0.5 0.5 0.5 - 0.5 50 0.05 - 2 2.8 3.1 2.2 2.2 - 4.0 58,8 0.2. - - ^P 4- 3 3.4 5.0 5.0 5.0 - 8.0 65.0 0.4 _ 11 ^ five 1488340 table 2 The composition of the modifier Power spheroidization graphite, 7 The number of inclusions of graphite per 1 mm ² Cementite content 7 SG (relative to HB, Note MPa elongation 8 ₉ % MPa Famous 70 thirty 25 455 .0,1 3900 Non-graphite Proposed one 80 530 0 550 5.1 2100 correct spherical and vermicular shape Graphite ta- 2 95 700 - 0 610 7,8 1970 rovid forms Also 3 95 650 0 620 7.4 1970 -