SU1666546A1 - Method of producing high-strength cast iron with spheroidal graphite - Google Patents

Abstract

The invention relates to metallurgy and can be used in the manufacture of castings from nodular cast iron. The purpose of the invention is to increase the level of mechanical properties in various-mass massive castings. The proposed method includes smelting iron in an induction furnace, cerium mischmetall additive in the furnace crucible, releasing the melt into the ladle with the first part of the magnesium-containing ligature pre-inserted on its bottom and ferrosilicon, blowing the melt with compressed air, adding the arc-shaped patterns to the melt in the second part of the pattern. , removal of slag from the ladle, additive in the amount of 0.3 - 0.6 wt.% of a substance containing zirconium and rare-earth elements with the ratio between them 1: (1 - 3). Additional input into the molten iron ZR - REM containing a complex alloy or a mechanical mixture of two complex alloys will increase the level of mechanical properties in castings with wall thickness from 75 to 200 mm σ 1.13 - 1.24 times

δ 1.28 - 2.11 times and HB 1.06 - 1.15 times. 2 hp ff, 3 tab.

Description

The invention relates to metallurgy, in particular to the development of methods for producing nodular cast iron,

The purpose of the invention is to increase the level of mechanical properties in various massive castings.

The invention is illustrated by the measurement of a specific implementation. 0 Selection of the boundary limits of the modes of the proposed method for producing chsh

After the metal has been melted in the furnace, the chemical composition has been refined and thermo-time treated.

in cast iron 0.05-0.1% of the mass of the mismetal metal melt to neutralize harmful impurities of the iron (element - demodifiers), such as lead, mouse, bismuth, etc. ..

i The cast iron treated with cerium mismetal is poured into a casting ladle equipped for blowing0 85-95% of the calculated amount of magnesium-containing master alloy and 75-80% of the graphitizing modifier are loaded onto the bottom of the ladle, loaded with a piece of sheet steel, then the ladle is filled with metal and blown through for 1 5-2.5 min.

ABOUT

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As the gaseous medium, air, nitrogen, and argon can be used. After the metal is aged for 2–5 min, the slag is cleaned and the second Stage of the pig iron is processed and the graphitizing And magnesium-containing reagents are deposited layer-by-layer with reagents for 0.5 "- 1 min, holding the min, cleansing the rЈpakas. Then, the sony-containing modifier was placed in the bucket in the com- partment 0, S, 6% of the liquid liquid" ugun, was blown into the form of 0 min, and the bucket was poured into the metal

Separating the magnesium input and the gras of fitting reagents during iron processing during the purging process helps stabilize the modification process, increases the degree of assimilation of the input components, which leads to a decrease in the consumption of additives. At the same time, the metal sensitivity to the cooling rate is significantly reduced at 3-stage processing melt, which provides more than one non-native structure in massive castings, cooled with temperature gradient

Gradual treatment of the cast iron helps to completely globularize the grain, reduce the size and increase the number of globules, which significantly prolongs the preservation time of the modifying effect. Layering of reagents provides better absorption of the modifying elements (magnesium, calcium, REE), prevents them from a great waste

Additional input of rare-earth metals “-zirconium containing modifier in quantities of ve, 6% by weight of liquid iron with a ratio of zirconium to rare-earth metals from 1: 1: 3, followed by blowing in Te“ Oi5H min provides additional modification of iron with zirconium and rare-earth metals, which contributes to the crushing of graphite inclusions in massive cast iron differential sections, increasing the mechanical properties of cast iron, as well as increasing the duration of the modifying effect. RZM - zirconium modifier contains, wt%: REM 5-30; zirconium 5-10; talnre "silicon, iron.

As a rare-earth metal of zirconium modifier, you can use a mecha-mixture of rare-earth silicon-silicon alloy,

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for example, FSZORZMZO and silica zirconium with an appropriate ratio of zirkons to rare earth metals.

When introducing REM "-Zirconium modifier in an amount of only 0.3%, the effect of its modifying effect is weak; Zirconium modifier in bone sections of massive castings separate inclusions of tsegentite appear, leading to a decrease in the strength of cast iron, especially its plastic property.

The ratio in the zirconium and REM modifier, equal to from 1: 1 to 1: 3, ensures that when the ratio of zirconium to rare-earth metals goes beyond, i.e., 1: 3.2, the effect of modification deteriorates, the mechanical properties reduce - This is apparently due to de "- modifying the effect of increased levels of rare-earth metals. With a lower content of rare-earth metals in the modifier (the ratio of zirconium: rare-earth metals, equal to 1: 0.95), the modifying effect of rare-earth metals does not provide a compact form of graphite inclusions in massive sections of castings, respectively, and the mechanical properties of cast iron are reduced. I

Example The smelting of cast iron was carried out in an ICTNOM2, induction furnace. Before the treatment, the cast iron had the following chemical composition, mass%: carbon 3.8; silicon 1.65; manganese 0.6; sulfur 0, OZD {phosphorus 0.06, the melt was superheated to 1450 ° C, kept in the furnace for 15 minutes, slag removed, 7 kg of cerium mismetal grade were introduced. Preheated to 700g-800 ° C, a ladle equipped for purging was injected with 1.8% by weight of the melt or 90% of the total estimated amount of magnesium-containing ligature (magnesium content 8%), then 1.1% by weight of metal or 75% of the total calculated amount of ferrosilicon F7575 reagents were loaded by cutting steel of grade St 3 in the amount of 2% by weight of the metal. Then cast iron was poured into the ladle and metal was purged for 2 minutes. "After this, the caster" —with cast iron, 4 minutes lived, the putty was removed, and then layers of

0.38% of ferrosilicon (25% of the calculated amount of the reagent) and 0.2% of the magnesium-containing ligature were injected and the melt was purged with air for 50 s. After removing the sponge, 0.4% of the REM-zirconium modifier was inserted into the metal mirror, wt0%: P31I 20; zirconia 10; the rest is silicon, iron

Air was purged for 40 s. Then the forms were cast. Other variants of the method for producing pig-iron with a spherical shape of graphite were obtained in accordance with the boundary parameters of the consumption of reagents. For comparative analysis, a well-known method of obtaining high-strength iron according to auth. evo № 1296589

The results of the comparative tests are presented in Tables 1 and 2.

As follows from Tables 1 and 2, the addition of a substance containing zirconium and rare-earth metals to the pig iron melt, as well as the subsequent blowing of the melt with air, made it possible to increase 1.13-1.24 times; fl 1.28-2.11 times on the IW 1.06-1.15 times.

Claims (1)

Invention Formula 1 "A method of producing high-strength nodular cast iron, including smelting iron in an induction furnace, a cerium mischmetal additive in the furnace, a melt is released into a ladle with the first containing magnesium alloy ligature and ferrosiliconite pre-inserted at its bottom, five 0 melt blown with compressed air, additive to the melt mirror, into the ladle of the second portion of magnesium-containing ligature and ferrosilicon, removal of slag and subsequent casting of iron, characterized in that, in order to increase the level of mechanical properties in different massive castings, after removing the spat from the ladle to the melt additionally set in an amount of 0.3-0.6% by weight, a substance containing zirconium and rare-earth elements at a ratio of 1 :(), and then subsequent melt blowing 2 The method according to claim 1, characterized in that a complex alloy of the following composition is used as a substance containing zirconium and rare earth elements, wt0%: Zirconium 5-10 Rare Earth 5-30 Iron5-25 Silicon Else I 0 3. The method according to p. 1, distinguished by the fact that, as a substance containing zirconium and rare earth elements, a mechanical mixture of complex alloys is used, 5 in the following ratio between them, Complex alloy containing rare earths 50-80 0 Complex alloy ferrosilikotsirkoni Else Table 1 five Proposed 1 Options 20  The composition relates to a mechanical mixture containing PHZO RZMZO 60%; FSTSr Y 40%, 20 15 Rest Comparative test results 50-90 50-90 5MO 80-100 90-110 80-100 90-110 80-100 90-110 0.3 1: 1  30-45 35.5 1-3 - prototype; 4-10 claimed method; 10 refers to the input of a mechanical carry composition; 11-13 outside of the claimed parameters. Continuation of table 2 The results of comparative tests (continued) 3.4 3.0 3.6 7,6 thirty  200 217 200 220 210 229 225 7.4 7.4 7.2 7.4 7.2 7.2 235 230 235 229 230 229 table 2 0 0 0 580 590 600 680 562 570 566 660 540,546,541 653 540 524 522 640 The experiments used the codifier of the composition of the type 190 18V FO1g7 (6.5-7.5 mg; 139 18 0.3-0.51 REM, 0.3-0.5Z Ca, 190 182 the rest is silicon, iron). Consumption modnfika-210 210 torus - 2-2.21 by weight liquid cast iron. As 210 210 graphitic acid additives 210 209, ferrosilicon 215 209 С75 was used. Its consumption was 210 209 1.3-1.61. The temperature of cast iron 215 210 when modifying 1430-220 209 1450VS The modes of blowing pig iron: pressure of compressed air 0.5-0.6 Sh, time of Nerves blowing 2-2.5 min, second 40-50.c, third 3 (MO s.