SU543684A1 - Modifier - Google Patents

Description

(54; MODIFIER

This invention relates to ferrous metal, in particular, to electrometallurgy of complex modifiers based on rare-earth metals (REM; for alloying and modifying steels and alloys.

The known composition of the modifier containing (in%. ;: REM 7-45, calcium 2-25, Fe 3-13, C 0.05-0.15, Si - the rest.

The disadvantages of the known composition are Cu, the high silicon content in the alloy, which does not allow its use for alloying and modifying low silicon (up to 0.4% Si; high speed steels and alloys. Due to the low specific weight of the alloys

The rare-earth metals with silicon and calcium, constituting 4.0-5.0 g / cm for this alloy, the absorption of rare-earth metals when alloying steel and alloys does not exceed 307 °. In addition, the introduction of this alloy into steel is accompanied by the appearance of a pyro effect.

The aim of the invention is to develop a modifier composition, which, along with the preservation of modifying effects in steels and alloys from known alloys with REM, would also increase the beneficial use of REM, eliminate the pyroeffect and reduce the cost of the finished product.

To achieve this goal, a modifier has been proposed, in which cobalt has been additionally introduced and the ingredients are taken in the following ratio (in weight,% ;:

Cobalt 49.5 - 87.5

Carbon0.05-0.5

Iron0,5 - 2,0

Earth to Earth

MetalsEverything.

Cerium concentrates CeO - 5 O%, (Pr) 0 are used as REM in the preparation of a modifier on its basis.

-45%, (Y + Sm + Gfdto, and other REM -5% or yttrium (YiOj - 25%, SEO) - Ya5%.

 - 5-10%, S-m20j- 10-15%, OCT. - REM-5-8%; enriched concentrates, as well as individual cerium oxides (CeO.;, yttrium (Y20j) and other rare-earth metals). Cobalt is introduced into the alloy either as a metal powder or as cobalt oxides directly into the mixture to produce an alloy based on its content. not less than 5% of cobalt. Reducing the content of cobalt below the specified limit will result in the formation of pure, chemically unrelated individual REM 2 in the alloy and a decrease in the specific gravity of the alloy. This may lead to the formation of REM carbides during the preparation of melt and increased rarefaction of rare-earth metals when used in steel. In addition, the lower limit for cobalt (49.5%) also determines the upper limit for carbon (0.5% because the lower content of cobalt in the modifier, as shown above , leads to the presence of free REM and to the intensive formation of their carbides. Reducing the content of cobalt in the modifier significantly reduces its specific weight, which has a negative effect on the assimilation of REM when the modifier is introduced into the steel. A decrease in REM in the modifier of less than 1O% or an increase in cobalt and more than 87.5 leads to the formation of a low-melting eutectic (t. Pl. 12OO C), which makes it difficult for the modifier to get, t, k, the minimum temperature of reduction of REM oxides even in vacuum at rarefaction mm Hg Art. is 1450-1500 In addition, a low content of REM in the modifier will lead to an increased consumption of modifier, a decrease as a result of this temperature of the metal being modified, and, as a result, unstable and low absorption of REM. The modifier of the proposed composition was obtained under laboratory conditions in a TBB-5 type furnace using a vacuum thermal method. Concentrates of cerium or yttrium subgroups or concentrates enriched with yttrium or pure oxides of yttrium Y Oj as the most difficult to restore in thermodynamic terms were used as REM-containing raw materials in various variants. These materials were briquetted together with metal powder of cobalt or its oxides and carbonaceous reducing agent taken by stoichiometry on the basis of the complete reduction of oxides of rare-earth metals and cobalt. The briquetted mixture was stirred into a vacuum furnace, where they were staged heated to 145 ° -153 ° C and then decreased up to 1050-1150 Cs excluding the melting of the final product, with a vacuum of 0.6-2-10 mm Hg. Art. with holding at this temperature until complete cessation of gassing. Then the furnace was cooled to 150-80 ° C while maintaining a vacuum of 5-0.1 mm Hg. then the alloy was removed from the furnace. The resulting product was tested in the smelting of fast cutting steel Р6М5К5 as a microalloying and modifying additive. In tab. 1 shows the chemical composition of the modifier obtained using various raw materials.

4 A modifier based on RZM bkp tested in the smelting of steelmaking steel R6M5KE in the Edukdonnobob BZhS furnace type LPZ-67. For comparison, Mishmetall was used as a REM-containing microalloying additive (RETA 67-58; research data is given in Table 2. In all cases, the weight of the R6M5K5 steel being modified was 30 kg. According to the previously described tests, STV occurs at a residual content of REM in steel equal to 0.08-0.1%. The tests were carried out in such a way that, with the introduction of various REM-s with the holding modifiers, to achieve in steel the same residual content of REM that provides an increase in operating From the data given in Table 2, the consumption of modifiers for the composition in terms of REM is about 2 times less than that of the standard mischmetall and the absorption of REM increased from 28.7 to 5 O-57%, which accordingly, it reduced the consumption of rare-earth metals in general. The increase in the assimilation of rare-earth metals with the addition of modifiers of the proposed composition containing 50-86% Co is explained as follows: -the indicated alloys have an increased density (6.5-8 g / cm), compared to Misch metal (4.7-5.5 g / cm) and silicon alloys with REM (4.4-4.7 g / cm which creates more benefit favorable conditions for its immersion in the alloy, thereby reducing the surface contact with air, the degree and rate of oxidation of rare-earth metals; - rare earth metals in the form of the claimed cobalt modifier are well absorbed by the modifiable steel, also containing cobalt, since rare earth metals with 8 cobalt form compounds; - the additive of the developed modifier does not exhibit the pyroelectric effect, since rare-earth elements are in intermetallic compounds with cobalt, which sharply reduces their oxidability. Thus, the application of the proposed modifier will reduce the consumption of rare-earth metals by 50% on average. In addition, the cost of 1 ton of rare-earth metals in the proposed modifier obtained by the method described above is about 1.5–2 times lower than in an electrically missed metal, the cost of 1 ton of rare-earth metals in which is about 10 thousand rubles.

modifier and its relatively low for micro-alloying and modifying the cost becomes obvious technical-eco-heat-resistant and heat-resistant steels to alloys, the nominal efficiency of using it containing cobalt.

543684

9

The results of testing the claimed modifier during smelting

R6M5K5 steel

Alloy 1

15453,9OD

Alloy 2

12761,20,1

Alloy 3

42552.0OD

Mish metal

(RETA 67-58)

Claims (1)

1121040.1 Claims of the invention A modifier containing rare earths (thalls, iron and carbon, is distinguished by -11 and so that, in order to use rare-earth metals and eliminate the pyroelectric effect while simultaneously treating and modifying steels and alloys table 2 55.28 49.13 57.85 28.7 rocks, it additionally contains cobalt in the following ratio of ingredients (in weight, Cobalt49.5 - 87.5 Carbon0.05-0.5 Iron0.5 - 2.0 Rare-earth metals Else.