SU740837A1 - Modifying mixture - Google Patents

Description

I

This invention relates to ferrous metallurgy, in particular, to the modification and refining of steel and alloys.

Known complex modifier containing the following components, wt.%: Magnesium 1.0-10, fluorspar 10-25, yttrium fluoride 2-10, fluoride rare-earth metals 3-25, silicocalcium - the rest fl.

The disadvantage of this cog / plox alloy is the low modifying efficiency, due to the fact that magnesium and alloys are evaporated relatively quickly in steel, and rare-earth fluorides are sufficiently thermodynamically strong compounds and for the reduction of rare-earth metals from fluorides, a significant consumption of calcium and magnesium is required, which reduces the effect of modification. The complex alloy weakly refines the steel, since the slag formed by the treatment of steel has a low asi: or the ability to mold against the non-metallic inclusions that are formed.

It has low fluidity and little protects the active components of the mixture from burnout.

The aim of the invention is to modify the modifying and refining capacity of the mixture.

11el is achieved by the fact that the modifying mixture additionally contains cypochemistry, silicobarium, lime and corundum, with the following ratio of components, weight. %:

Silikomishmetall10-ZO

Silikokaltsiy1O-29

Silicobarium10-30

Magnesium1-5

Lime15-30

Corundum 5-10

Hydrofluoric ballast: 5-10

Silikomishmetall, silicocalcium, snobarium and magnesium are introduced into the mixture to give it a modifying ability, slag-forming (lime, corundum, fluorspar) - to increase the refining ability of the mixture and protect

burnout elements. Silikomishmetall is introduced into the mixture in a vvde alloy simish, siitmish (TU-14 5-50-74) or FSMI (TU-14-141 58-76). Rare-earth metals favorably change the composition and shape of nonmetallic inclusions, transform them into a globular shape, and —wind the anisotropy of the properties of rolled steel. Alkaline earth metals, calcium and barium contribute to obtaining the most favorable type of nonmetallic inclusions in steel-oxide in sulfide shell. When the content of Schmetall's silica in the mixture is less than 10%, the modifying capacity of the mixture is reduced, its content is more than 30% is not advisable since it increases the cost of the mixture, and the improvement of properties is moderate. Silicocalcium should be injected into the mixture in the form of the grades CKIO and CK15 (GOST 4762-71) ha, in which case the absorption of calcium increases. When the content of silica-gel in a mixture is less than 10%, its effect on the properties of the treated steel mixture is small, while its content is more

30% of the modification is accompanied by a noticeable pyroelectric effect and steel boring, which is undesirable, since the release of metal is possible. Silicobarium (TU-14-1461-6-73) is introduced into steel for primary grinding. . structures and changes in the composition and shape of non-metal 1-month inclusions. When its content in the mixture is less than 10%, its effect on the properties of the modified steel is not very noticeable; the content of the silicobar mixture in the mixture is 30% impractical because the mixture becomes more expensive. Magnesium in the composition of the mixture performs the role. active modifier, significantly grinding the primary structure and reducing the chemical heterogeneity of steel. Granular magnesium grades MHP-1 or MHP-2 are used for uniform distribution in the mixture. When the content of magnesium in the mixture is less than 1%, its effect on the properties of the steel being treated is little noticeable; if its content in the mixture is more than 5%, the modification is accompanied by smoke emission and pyro effect. Moreover, the possibility of splashing metal from the ladle is not excluded, therefore the magnesium content in the mixture should not exceed 5% .

The molten substances were introduced into the mixture to produce fast-forming liquid-mobile slag, protecting magnesium and complex alloys.

. from burnout and having a high refining ability with respect to harmful impurities and products, deoxidation and modification. Top and bottom

 There is always in the furnace slag in an amount of from 15 (mostly) to 60% (sour), and when steel is introduced into the ladle, the slag is also in the emulsified state together with the metal. The lower limit of lime (CaO) - 15% is selected from the condition for obtaining low-melting slag, which has the necessary basicity for the assimilation of sulfide inclusions. When the content of lime in the mixture is less than 15% itMegT slag low refining ability. The content of lime in the mixture above 30% is undesirable because of the increase in the slag melting temperature and the decrease in its assimilating ability to nonmetallic inclusions. Corundum (A2-jO is used to dilute the slag. Corundum content less than 5% is not enough to produce liquid slag. When content is slag refractoriness rises in a mixture of more than 10%, which is undesirable. Fluorspar (fluorite) is introduced into the mixture to accelerate the time of slag formation and liquefaction. At the same time, plated spar effectively liquefies and reduces viscosity Both basic and acidic slags increase their refining ability. When less fluorspar is introduced into the mixture, spar lengthens the formation time of the Fioro slag fluid, which reduces e (}) the efficiency of lime, corundum and fluorspar selected from the feasibility of slag optimal physicochemical properties. When the composition of the individual components of the slag-forming slag below the lower and upper upper limits, the refining and modifying ability of the mixture deteriorates. It is advisable to use the modified mixture for treating open-hearth, converter and electric steels in a ladle. The optimum mixture consumption is 4-6 kg / ton steel. The maximum size of ferroalloys and slag-forming materials should not exceed 30 mm. The ratio of the slag-forming compounds in the mixture is determined by the condition for the formation of a liquid-moving slag, which is necessary for the assimilation of solid and solid oxide and sulfide non-metallic inclusions. The basis of all railway sliding slags is the CaO-Si 3 system.

modifying. When its content in the mixture is more than 10%. the emission of smoke and the emission of fluorinated gases increases, which leads to pollution of the surrounding atmosphere, and the improvement in the quality of the formed slag is insignificant. 5 pilot melts of steel ZOL were melted. The steel is preliminarily in a furnace, deoxidized with manganese (0.5%), silicon (0.3%) and aluminum (0.1%), treated into a ladle with an experimental modifying mixture and a complex modifier in an amount of 5 kg / t and cast ingots

5O kg The chemical composition of the modifying blend and in% is given in table. 1. The well-known complex modifica- tion p- has the following chemical composition, weight,%: | aluminum 5, fluorspar 20, fluoride 6, fluoride REM 15, silicocalcium - the rest. After cutting the ingots and heat treatment of the blanks according to the mode: normalization at 890 ° C, holding for 30 minutes, tempering at 620 ° C for 2 hours, testing the mechanical properties of ZOL steel (Table 2).

Table

The tests show that we offer a modifying mixture that increases by 2-3 kgf / mm the strength characteristics of the steel ZOL and by 10-20% plasticity. Impact viscosity at room temperature by 15-40% and almost 2 times higher at - 40 C. The contamination index of steel with non-metallic inclusions on guest 1778-70 is 2-2.5 times lower than steel treated with the same number of known modifiers. Thus, modifying the mixture according to the refining method

The impact of steel properties on steel properties has significant advantages over steel treated with a known complex modifier. The invention formula Modifying mixture containing magnesium, silicocalcium, fluoride mat, characterized in that, in order to increase its modifying and refining ability, it additionally contains silico-metallic, si-

  : ... ®

likobary, ivest. I lay down Korund 5-10

Our ratio of components, weight. %: Fluorspar 5-10

S il ikb MISH metal 10-30 Sources of information

Silikokaltsy 10-29prinye ing in attention during the examination

Silicobaric 10-305

Magnesium 1-51. USSR author's certificate

Lime 15-30№ 364688, cl. C 22 C 35/00, 1972.

Claims (1)

Claim "A modifying mixture containing magnesium, silicocaldium, fluorspar, characterized in that, in order to increase its modifying and refining ability, it additionally contains silicomishmetapl, si." * "'. .. * *, 740837 _ ι ι "α ·". · --— · lycobarium, ivest and- “orund in the following ratio of components, weight. %: With silt ikb mish met all 10-30 Silicocalcium 10-29 Silicobarium 10-30 Magnesium1-5 Lime15-30 Corundum 5-10 Fluorspar 5-10