Production process of tire cord steel with low carbon dioxide emission

Abstract

The invention discloses a production process of tire cord steel with low carbon dioxide emission, which relates to the technical field of steel production and sequentially comprises electric furnace smelting, refining, continuous casting, blank grinding and rolling. Wherein a raw material for electric furnace smelting is scrap steel. According to the method, 100% of scrap steel is adopted as ingredients, molten iron is not adopted, physical hot melting is completely achieved through electric arc energization of an electric furnace, and due to the fact that molten iron does not exist, CO2 emission is small or basically no emission exists, CO2 emission per ton of tire cord steel is smaller than or equal to 1.0 ton and is far lower than the CO2 emission level of a converter.

Description

Technical Field

[0001] The invention relates to the technical field of steel production, and in particular to a production process of cord steel with low carbon dioxide emission. Background Art

[0002] In order to make the cord steel wire rod have excellent cleanliness and drawing performance, the blast furnace-converter is often used for smelting in the metallurgical field. However, the smelting cycle of the blast furnace-converter is long, and the carbon emission level in the production process is high, which is not environmentally friendly. Nowadays, electric furnace smelting technology is also used for steel cord production, but the proportion of molten iron is high, and there are also problems such as high carbon emission levels and difficult to control steel quality. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the disadvantages of the prior art and provide a production process for cord steel with low carbon dioxide emission.

[0004] In order to solve the above technical problems, the technical solution of the present invention is as follows: A production process of cord steel with low carbon dioxide emission, comprising electric furnace smelting, refining, continuous casting, billet grinding and rolling in sequence; Wherein, the raw material for electric furnace smelting is scrap steel.

[0005] As a preferred solution of the production process of the low carbon dioxide emission cord steel described in the present invention, the electric furnace smelting process adopts one-time slag making to control the P element content in the molten steel, so that the final P element content is less than or equal to 0.02%, and the C content is less than or equal to 0.20%.

[0006] As a preferred solution of the production process of the cord steel with low carbon dioxide emission of the present invention, wherein: in the electric furnace smelting process, silicon and manganese are used for deoxidation of the steel.

[0007] As a preferred solution of the production process of the cord steel with low carbon dioxide emission described in the present invention, the refining process adopts LF refining furnace for refining, silicon carbide for deoxidation, lime and fluorite or refined slag for slag making and desulfurization, the slag basicity is R2.0-3.0, and after desulfurization, slag skimming or slag pouring is carried out, and then pre-melted slag or lime and quartz sand are added again for slag making and slag adjustment, and the slag basicity is controlled to be R0.6~1.3.

[0008] As a preferred solution of the production process of the cord steel with low carbon dioxide emission described in the present invention, the soft stirring time in the refining process is greater than 20 minutes.

[0009] As a preferred solution for the production process of the cord steel with low carbon dioxide emissions described in the present invention, wherein: in the continuous casting process, the continuous casting machine pulling speed is controlled to be 1.8-2.1m / min, the superheat of the molten steel is controlled to be 15-35°C, the specific water content is 1.2-1.8L / kg, electromagnetic stirring of the crystallizer and electromagnetic stirring at the end of solidification are adopted, and the central segregation coefficient of the continuous casting billet is less than or equal to 1.10.

[0010] As a preferred solution of the production process of the cord steel with low carbon dioxide emission of the present invention, wherein: the soaking temperature of the heating furnace in the rolling process is controlled to be 1160-1280°C, and the total time in the furnace is ≥120min.

[0011] As a preferred solution for the production process of the low carbon dioxide emission cord steel described in the present invention, the rolling process adopts the Stelmor cooling method to control cooling, the wire rod spinning temperature is 870-930°C, the pearlite phase transformation starting temperature is controlled at 550-630°C, the cooling rate before the phase transformation reaches 10-40°C / s, and the cooling rate during the phase transformation is -5-10°C / s.

[0012] The beneficial effects of the present invention are: The ingredients of the present invention use 100% scrap steel instead of molten iron, and are completely melted by electric arc in an electric furnace. Since there is no molten iron, CO2 emissions are less or basically non-existent, so that CO2 emissions per ton of cord steel are ≤1.0 ton, which is much lower than the CO2 emission level of the converter. DETAILED DESCRIPTION

[0013] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific implementation methods.

[0014] The present application provides a production process of a cord steel with low carbon dioxide emission, which production process comprises the following steps in sequence: electric furnace smelting, refining, continuous casting, billet grinding and rolling.

[0015] Specifically, the raw material for electric furnace smelting is 100% scrap steel, and no molten iron is used. High-quality scrap steel is used, such as plate edge wire, ball flat, ship plate, thread cutting head and tail, etc. The residual elements of the above high-quality scrap steel are relatively low.

[0016] The electric furnace smelting process uses one-time slag making to control the P content in the molten steel. The electric furnace performs foam slag and flow slag operations. The final target P content is ≤0.010%, and the C content is ≤0.08%. Silicon and manganese are used for steel tapping, and aluminum or aluminum-containing deoxidizers are strictly prohibited for deoxidation. The tapping temperature is 1600-1680℃ to prevent slag.

[0017] In the refining process, the steel is refined in the LF furnace after the electric furnace is tapped. The LF furnace is used to refine silicon carbide for deoxidation. It is strictly forbidden to use aluminum or aluminum-containing deoxidizers to reduce the equilibrium oxygen content in the molten steel. Lime and an appropriate amount of fluorite, or refined slag, are used for slag making and desulfurization, and the slag basicity is R2.0-3.0. After desulfurization, the slag is removed or poured, and then the pre-melted slag, or lime and quartz sand are added again for slag making and slag adjustment, and the slag basicity is controlled to R0.6~1.3. According to the N content and inclusions, RH or VD treatment and duration should be selected to ensure that the soft stirring time is more than 20 minutes.

[0018] In the continuous casting process, the casting speed of 140mm×140mm-160mm×160mm square billet continuous casting machine is 1.8-2.1m / min (200mm×240mm square billet 1.0-1.5m / min), the superheat of molten steel is controlled at 15-35℃, the specific water volume is 1.2~1.8L / kg (200mm×240mm square billet 0.4-1.0m / min), and the crystallizer electromagnetic stirring and solidification end electromagnetic stirring are adopted. The center segregation coefficient of the continuous casting billet is ≤1.10 (C center / C average). The continuous casting billet can be directly rolled by high-speed wire.

[0019] In the billet grinding process, the continuous casting billet is shot blasted and flaw detected, and then ground according to the surface condition of the continuous casting billet. If the billet surface quality is good, it can be rolled directly or the billet can be hot-rolled.

[0020] In the rolling process, the soaking temperature of the continuous casting billet heating furnace is controlled at 1160-1280℃, and the total time in the furnace is ≥120min. After descaling, rough, medium, finishing rolling and sizing rolling, only the Stelmor cooling method is used to control cooling, the wire rod extrusion temperature is 870-930℃, and the pearlite phase transformation start temperature is controlled at 550-630℃; the cooling rate before the phase transformation reaches 10-40℃ / s; the cooling rate during the phase transformation is -5-10℃ / s.

[0021] The following is further described by means of specific examples.

[0022] Table 1 shows the chemical compositions and their mass percentages of Example 1 and Example 2.

[0023] Table 1 Example 1 provides a production method of cord steel with low carbon dioxide emission, which adopts electric furnace smelting and uses 100% preferred scrap steel (80% edge wire + 20% bulb flat) to smelt cord steel, electric furnace smelting to make foam slag and flow slag and slag replacement operation, LF refining first makes high basicity slag for desulfurization and then slag removal, and then re-makes acidic slag, controls residual elements and inclusions such as Cr, Cu, P, S, Al, N, etc., continuously casts into 150mm×150mm small squares, directly hot-rolls into Ø5.5mm wire rods, so that the cord steel emits 0.8 tons of CO2 per ton of steel, and specifically comprises the following steps: Scrap steel ingredients: 100% scrap steel is used for electric furnace smelting, and the preferred plate edge wire and bulb flat are used. The residual elements are relatively low. The ingredients are 80% edge wire + 20% bulb flat, and no molten iron is used.

[0024] Electric furnace smelting: The electric furnace smelting process adopts one-time slag making to control the P content in the molten steel. The electric furnace shall perform foam slag and flow slag operations. The final target P content is 0.011%, and the C content is 0.07%. Silicon and manganese are used for deoxidation in the converter. It is strictly forbidden to use aluminum or aluminum-containing deoxidizers for deoxidation. The tapping temperature is 1620℃ to prevent slag.

[0025] Refining: After the steel is tapped from the electric furnace, it is refined in the LF furnace. The LF furnace is used to refine silicon carbide for deoxidation. It is strictly forbidden to use aluminum or aluminum-containing deoxidizers for deoxidation to reduce the equilibrium oxygen content in the molten steel. Lime and an appropriate amount of fluorite are used for slag making and desulfurization, and the slag basicity is R2.6. After desulfurization, the slag is skimmed, and then 1 ton of pre-melted slag is added again for re-slag making, and the slag basicity is controlled to R0.9, and the soft stirring time is 26 minutes.

[0026] Continuous casting: When using a 150mm×150mm square billet continuous casting machine, the casting speed is 2.0m / min, the superheat of the molten steel is controlled at 25℃, the specific water volume is 1.4L / kg, and electromagnetic stirring of the crystallizer and electromagnetic stirring at the end of solidification are adopted. The center segregation coefficient of the continuous casting billet is ≤1.10 (C center / C average).

[0027] Billet processing: The billet surface quality is good and is directly hot-rolled.

[0028] Rolling: The soaking temperature of the continuous casting billet heating furnace is controlled at 1180℃, and the total time in the furnace is 150min; after descaling, rough, medium, finish rolling and sizing rolling, only the Stelmor cooling method is used to control cooling, the wire rod spinning temperature is 880℃, and the pearlite phase transformation starting temperature is controlled at 550-630℃; the cooling rate before phase transformation reaches 10-50℃ / s; the cooling rate during phase transformation is -5-10℃ / s.

[0029]

[0030] Table 2 Table 2 shows various data indicators of carbon dioxide emission of the cord steel produced in Example 1.

[0031] Example 2 provides a production method of cord steel with low carbon dioxide emissions, which adopts electric furnace smelting and uses 100% preferred scrap steel (60% ship plate + 40% thread cut head) to smelt cord steel, electric furnace smelting to make foam slag and flow slag and slag replacement operations, LF refining first makes high basicity slag for desulfurization and then slag removal, and then re-makes acidic slag, and then VD vacuum degassing is performed to control residual elements and inclusions such as Cr, Cu, P, S, Al, and N, and continuous casting is performed into 200mm×240mm small squares, and directly hot-rolled into Ø5.5mm wire rods, so that the cord steel "from cradle to gate" has a CO2 emission of 0.9 tons per ton of steel, and specifically includes the following steps: Scrap steel ingredients: 100% scrap steel is used for electric furnace smelting, and the preferred ship plate and threaded cut head are adopted to control the residual elements. The ingredients are 60% ship plate + 40% threaded cut head, and no molten iron is used.

[0032] Electric furnace smelting: The electric furnace smelting process uses one-time slag making to control the P content in the molten steel. The electric furnace is required to perform foam slag and flow slag operations. The final target P content is 0.012%, and the C content is 0.06%. Silicon and manganese are used for deoxidation in the converter. It is strictly forbidden to use aluminum or aluminum-containing deoxidizers for deoxidation. The tapping temperature is 1630℃ to prevent slag.

[0033] Refining: After the steel is tapped from the electric furnace, it is refined in the LF furnace. The LF furnace refines silicon carbide for deoxidation. It is strictly forbidden to use aluminum or aluminum-containing deoxidizers for deoxidation to reduce the equilibrium oxygen content in the molten steel. Lime and an appropriate amount of fluorite are used for slag making and desulfurization, and the slag basicity is R2.5. After desulfurization, the slag is skimmed, and then 1 ton of pre-melted slag is added again for re-slag making, and the slag basicity is controlled to R0.9. Then it is subjected to VD vacuum treatment, and the soft stirring time is 28 minutes.

[0034] Continuous casting: When using a 200mm×240mm square billet continuous casting machine, the casting speed is 1.2m / min, the superheat of the molten steel is controlled at 28℃, the specific water volume is 0.6L / kg, and electromagnetic stirring of the crystallizer, electromagnetic stirring at the end of solidification and light pressure are used. The center segregation coefficient of the continuous casting billet is ≤1.06 (C center / C average).

[0035] Billet processing: The billet surface quality is good and is directly hot-rolled.

[0036] Rolling: The soaking temperature of the continuous casting billet heating furnace is controlled at 1220℃, and the total time in the furnace is 220min; after descaling, rough, medium, finish rolling and sizing rolling, only the Stelmor cooling method is used to control cooling, the wire rod spinning temperature is 870℃, and the pearlite phase transformation starting temperature is controlled at 550-630℃; the cooling rate before phase transformation reaches 10-50℃ / s; the cooling rate during phase transformation is -5-10℃ / s.

[0037]

[0038] Table 3 Table 3 shows various data indicators of carbon dioxide emission of the cord steel produced in Example 2.

[0039] It can be seen from this that the technical solution of the present application makes the CO2 emission per ton of steel of cord steel ≤1.0 ton, which is much lower than the CO2 emission level of the converter.

[0040] In addition to the above embodiments, the present invention may also have other implementation modes; any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A production process for cord steel with low carbon dioxide emissions, characterized in that: It includes electric furnace smelting, refining, continuous casting, billet grinding and rolling in sequence; Wherein, the raw material for electric furnace smelting is scrap steel.

2. The production process of low carbon dioxide emission cord steel according to claim 1, characterized in that: The electric furnace smelting process adopts one-time slag making to control the P element content in the molten steel, so that the final P element content is less than or equal to 0.02%, and the C content is less than or equal to 0.20%.

3. The production process of low carbon dioxide emission cord steel according to claim 1, characterized in that: In the electric furnace smelting process, the steel is deoxidized by using silicon and manganese.

4. The production process of low carbon dioxide emission cord steel according to claim 1, characterized in that: The refining process adopts LF refining furnace for refining, silicon carbide for deoxidation, lime and fluorite or refined slag for slag making and desulfurization, the slag basicity is R2.0-3.0, and after desulfurization, slag is skimmed or poured, and then pre-melted slag or lime and quartz sand are added again for slag making and slag adjustment, and the slag basicity is controlled to be R0.6-1.

3.

5. The production process of low carbon dioxide emission cord steel according to claim 1, characterized in that: The soft stirring time in the refining process is greater than 20 minutes.

6. The production process of low carbon dioxide emission cord steel according to claim 1, characterized in that: In the continuous casting process, the casting speed of the continuous casting machine is controlled to be 1.8-2.1m / min, the superheat of the molten steel is controlled to be 15-35°C, the specific water content is 1.2-1.8L / kg, electromagnetic stirring of the crystallizer and electromagnetic stirring at the end of solidification are adopted, and the central segregation coefficient of the continuous casting billet is less than or equal to 1.

10.

7. The production process of low carbon dioxide emission cord steel according to claim 1, characterized in that: In the rolling process, the soaking temperature of the heating furnace is controlled to be 1160-1280° C., and the total time in the furnace is ≥120 min.

8. The production process of low carbon dioxide emission cord steel according to claim 1, characterized in that: The rolling process adopts the Stelmor cooling method to control cooling, the wire rod spinning temperature is 870-930°C, the pearlite phase transformation starting temperature is controlled at 550-630°C, the cooling rate before the phase transformation reaches 10-40°C / s, and the cooling rate during the phase transformation is -5-10°C / s.

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