SU1632984A1 - Mixture for refining, deoxidizing and alloying of steel - Google Patents

Abstract

The invention relates to the metallurgy of ferrous metals, 8 namely, steelmaking in electric arc steel-smelting furnaces with basic lining. The goal is to improve the quality and mechanical properties of steel. The mixture contains, wt%: lime or limestone to 14-15; fluorspar 44-45; silicocalcium 4-30; coke or coal 0.6-7; vanadium 5-29; titanium 2-4.4. The use of the mixture allows increasing the ultimate strength of steel by 9.5-10.8%, relative elongation by 10-12%, relative narrowing by 7-10%, impact strength 1.68-1.77 times and the surface hardness of steel by 14.6-25%. 2 tab. Yu

Description

The invention relates to the metallurgy of ferrous metals, namely to steelmaking in electric arc steel-smelting furnaces with a base lining.

The purpose of the invention is to improve the quality and mechanical properties of steel.

The proposed mixture for refining, deacidification and doping contains lime or limestone, fluorspar, silicocalcium, coke or gol, vanadium and titanium in the following ratio of components, wt.%:

Lime or

known to 14-15

Fluoric

spar.44-45

Silikokalilsh 4-30

Coke or

coal 0.6-7

Vanadium 5-29

Titanium2-4,4

The combined use of lime or limestone, fluorspar, silicocalcium, coke or coal, vanadium and titanium provides a complex effect on the quality of the metal in the following directions: the formation in the furnace of an active, liquid refining shpak with a high reduction potential, based on the created reducing conditions, The removal of sulfur and phosphorus is indicated, and the phosphorus is removed according to the scheme ECTSLPOVPTOLbooe ooo.

oo

U

ten

15

20

oh dephosphorization in the form of phosphides. When the melting is completed on the metal crystallization stage, an additional refining of its zeen from a phosphide eutectic is carried out. These processes provide improved quality and mechanical properties of the metal.

In the case of consumption of lime or lime less than 14 wt.%, The basicity of the slag phase decreases and, accordingly, its refining properties with respect to sulfur and phosphorus. The consumption of lime or limestone over 15 wt.% Leads to an increase in the melting temperature, viscosity and degree of slag heterogeneity, and consequently, to a decrease in its grnphus ability.

With the consumption of hydrofluoric pshat less than 44 wt.%, The molten liquid of the slag melt and the concept of calcium cations in it decrease, which leads to a drop in the reducing potential of the claque and, accordingly, to a decrease in the degree of desulfur. metal, an increase in the consumption of flipped about or in about uma t and more than 45 wt.% reduces the basicity of the furnace shpak.

The consumption of strong-calcium less than 4 wt.% Reduces the minimum concentration of calcium cations in the metal acceptable for the conditions of restorative cephosphorization; at the same time, the degree of oxidation of the metal increases; non-metallic inclusions, sulfur and phosphorus. When the silping consumption is increased by more than 30 wt.%, The concentration of silicon dioxide in the slag increases, which reduces its basicity and finishes.

In the case of coke or coal consumption less than 0.6 wt.%, The reduction potential of the gas-slag interface decreases, which leads to an increase in calcium loss by oxidation and, accordingly, to a decrease in the quality of the metal due to a decrease in the degree of desulfurization and reductive dephosphorization. The consumption of these materials over 7 wt.% Leads to the development of the reaction of formation of calcium carbide, which also reduces the rate of refining the metal from sulfur and phosphorus,

In the case of a vanadium consumption of less than 5 wt.%, The reduction potential of the metal decreases, while the reduction potential of the metal is 30.

40

45

55

0

five

0

0

five

ABOUT

five

the phosphate eutectic falls out along the grain boundaries, the coarse-grain structure falls, the values of the mechanical properties of the steel decrease. Vanadium consumption of more than 29% may intensifies the carbidization process in the metal structure, 5 which leads to a drop in the values of steel toughness.

When titanium consumption is less than 2 wt.%, The concentration of oxide nonmetallic inclusions in steel, serum and phosphorus increases, grain of the metal grows, wear resistance and impact strength of steel decrease. In case of titanium consumption over 4.4 wt.%, The metal contamination of refractory nonmetallic inclusions increases m, while there is a decrease in the values of the mechanical characteristics of the steel being melted. Sources of vanadium and titanium are ferrovanadium and ferrotite-en.

Example. The proposed mixture for refining deoxidation and alloying is used in the smelting of steel UG13.P in an electric arc steel-smelting furnace with basic lining. At the same time, the mixture is loaded 10–20 minutes before the end of the recovery period. Its consumption is 5-35 kg. // T.

Table 1 shows the compositions of the proposed mixture, which are used for melting in an electric arc furnace: compositions 1 and 2 correspond to the boundary contents of the components, compounds 3-6 to the average content, compositions 7 and 8 differ from those proposed, and one of the components is missing. As a known mixture used composition, wt.%: Aluminum 12,5; silicocalcium 18.5; hydrofluor boards 20; lime 49.

The results of melting steel using the proposed and known mixtures are given in table 2. The use of the proposed mixture makes it possible to increase the quality of the metal by reducing the sulfur concentration by 30–40 wt.%, Phosphorus by 25–37.5 May.%, Non-metallic inclusions by 43.8–500 wt.%. An important role in achieving a positive effect from the use of the proposed mixture belongs to the physical properties of the slag phase. The values of the initial melting point of the donkey when using

the composition of the mixture below on

4Q-50 ° C, viscosity at 0.3-0.4 N C / m2.

The positive effect of the proposed mixture on the structure of steel and the purity of the boundaries of its grains is associated with data on the increase in the values of mechanical properties (Table 2). As a result of using the proposed mixture, the ultimate strength ((Tg) of steel increases by 9.5-10.8%, relative elongation (a) by 10-12%, relative narrowing (1 я by 7-10%, impact strength (С} ц)) 1.8-1.77 times with

ten

20 ° С

properties, and the goal is not achieved (Table 2).

Claims (1)

Invention Formula A mixture for refining, deoxidizing and alloying steel, containing lime or lime, fluorspar, silicocalcium, characterized in that, in order to improve the quality and mechanical properties of steel, it additionally contains coke or coal, vanadium, and tees; 1.45.64 times when -5 .5 ta in the following ratio: Composting hardness (HV) by 14.6-25%. In case of using compounds 7 and 8 (Table 1) the quality of the metal deteriorates, the values of the mechanical properties of the steel decrease . The use of compounds 7 and 8 does not provide for the formation of fluid-moving slags with low values of solidus temperature and viscosity (Table 2). When using compounds 9-14 (Table 1), the object does not possess the specified 20 25 nanov, wt.%: Lime or known to Fluoric spar Silicocalcium Coke or coal Vanadium Titanium 14-15 44-45 4-30 0.6-7 5-29 2-4.4 properties, and the goal is not achieved (Table 2). Invention Formula A mixture for refining, deoxidizing and alloying steel, containing lime or lime, fluorspar, silicocalcium, characterized in that, in order to improve the quality and mechanical properties of steel, it additionally contains coke or coal, vanadium and titanium in the following ratio five nanov, wt.%: Lime or known to Fluoric spar Silicocalcium Coke or coal Vanadium Titanium 14-15 44-45 4-30 0.6-7 5-29 2-4.4 Table 1 14 15 14.5 14.5 122 sixteen 23 2 16 16 15 14.5 14.5 1.6 table 2