CN101831521A - Method for producing cord steel - Google Patents

Abstract

The invention discloses a method for producing cord steel, which comprises smelting, refining, continuous casting and rolling and specifically comprises the following steps of: 1, adding waste steel and molten iron raw materials into a converter, and raising quality requirements for the molten iron and the waste steel; 2, smelting the raw materials in the converter, and controlling the aim carbon content to be 0.30 to 0.70 percent; 3, controlling steel tapping; 4, refining the steel; 5, continuously casting billets, electromagnetically stirring the billets by using a crystallizer, and controlling the continuous casting pulling speed to be 2.0 to 2.6m/min; and 6, rolling wires at high speed, and rolling the billets to form cord steel coil rods by using a high-speed wire mill. The method saves the processes of molten iron desulfuration or molten iron three-removal pretreatment and RH or VD vacuum treatment of molten steel, saves electromagnetic stirring of two cooling zones and electromagnetic stirring of a tail end in continuous casting production, saves primary rolling cogging and steel ingot polishing, improves the yield, realizes reduction of cost, and saves energy.

Description

A kind of production method of cord steel

Technical field

The present invention relates to the ferrous metallurgy production field, be specifically related to a kind of production method and goods thereof of cord steel.

Background technology

Cord with steel in the intensity of steel, draw aspects such as dialling performance, purity of steel and inclusion size, form that high requirement is all arranged, be the representative products of ultra clean steel and the significant product of wire quality level, have the title of " wire rod superfine product ", it is one of steel grade of the highest, the production difficulty maximum of specification of quality in the wire fabrication, to smelt, each link such as rolling, processing all has higher technical requirements, is mainly used in automobile, plane tyre meridian.

At present, the production cord steel mainly contains following method both at home and abroad: method 1, dephosphorization, desiliconization and desophorization for hot metal → converter → LF → RH (VD) vacuum → bloom continuous casting → crystallizer induction stirring+two cold-zone induction stirring+terminal induction stirring; Method 2, desulfurizing iron → converter → LF → RH (VD) vacuum-treat → bloom continuous casting → crystallizer induction stirring+two cold-zone induction stirring+terminal induction stirring; Method 3, desulfurizing iron → converter → LF → RH (VD) vacuum-treat → die casting; Method 4, desulfurizing iron → converter → LF → RH (VD) vacuum-treat → continuous small-billet casting → crystallizer induction stirring+terminal induction stirring.

Method 1,2,4 also adopts two cold-zone induction stirring and terminal induction stirring except that adopting the crystallizer induction stirring, water coolant and power consumption increase; Method 1,2,3 adopts continuous casting blooms or static ingot, needs the secondary cogging, has increased cogging, reconditioning cost.

The common drawback of above-mentioned cord steel production method is: the one, all adopt hot metal pretreatment and vacuum processing technique process, and increased production cost; The 2nd, converter smelting all adopts " low catch carbon " homlolgation production, owing to contain impurity in the carburelant, a large amount of carburelants inevitably pollutes molten steel; The 3rd, there is technical sophistication in production technique, the cost height.

Summary of the invention

By Given this, the invention provides a kind of new process of production of cord steel, raw materials for production are claimed, first refining converter and ladle refining furnace control techniques are claimed, adopt continuous small-billet casting and high-speed wire rolling, produce the product that satisfies the cord steel specification of quality, desulfurizing iron or dephosphorization, desiliconization and desophorization for hot metal pre-treatment and molten steel have been reduced through RH or VD vacuum-treat, reduced two cold-zone induction stirring and terminal induction stirring in the continuous casting production, breaking down cogging and steel blank regrinding have been reduced, both improve output, reduced cost, saved the energy again.

To achieve these goals, the present invention is by the following technical solutions:

A kind of production method of cord steel comprises smelting, refining, and continuous casting and rolling comprises the steps:

Step 1 adds raw material steel scrap and molten iron in converter;

Molten iron requires: molten iron temperature 〉=1250 ℃, and the content of phosphorus, sulphur, titanium (mass percent) is in the molten iron: phosphorus≤0.100%; Sulphur≤0.050%; Titanium≤0.005%;

Steel scrap requires: be the heavy or medium-sized steel scrap of titaniferous, copper, zinc impurity element not;

Step 2, converter smelting, end point carbon is controlled at 0.30%～0.70%;

Step 3, tapping control,

Add pre-top slag in the tapping process, the raw material of pre-top slag is: pre-melted slag or/and lime or/and fluorite;

In the tapping process, when tap reach total amount 2/3rds the time, in ladle, add silicocalcium or/and calsibar alloy or/and Si-Ba alloy or/and silicon carbide or/and calcium carbide;

Step 4, refining,

Make refining slag in the LF refining furnace, the raw material of refining slag is: lime is or/and fluorite is controlled (Al in the refining slag ₂O ₃) content is less than 10%;

Refining time is:

L is the molten steel degree of depth in the ladle, and V is a different diameter inclusion floating speed

Step 5, continuous small-billet casting, crystallizer induction stirring, continuous casting pulling rate: 2.0～2.6m/min;

Step 6, high-speed wire rolling is rolled into the cord steel wire rod by high-speed rod-rolling mill.

Further, in the described step 4, the refining time of the big-and-middle-sized smelting furnace more than 100 tons is 60～100min.

Further, in the described step 5, the continuously cast bloom cross dimensions of producing is: 150 * 150mm ²

Further, in the described step 6,

Start rolling temperature control: 970 ± 50 ℃; Finishing mill temperature control: 900 ± 50 ℃;

Stanermo wind-cooling linear control: entrance roller table speed: 38～60m/min; Outlet section roller table speed: 40～65m/min;

Blower fan is opened 1～8, wherein 1～4 typhoon machine opening degree, 80%～100%, 5～8 typhoon machine opening degrees 60%～90%.

Further, described cord steel wire rod cross dimensions is φ 5.5mm, and sorbite content reaches more than 85% in the described cord steel wire rod.

Beneficial effect of the present invention is:

The present invention compares with other cord steel production technique, has the following advantages:

1, reduces desulfurizing iron or dephosphorization, desiliconization and desophorization for hot metal pre-treatment and molten steel through RH or VD vacuum processing technique process, realized the reduction of cost;

2, first sweetening process adopts " high catch carbon " smelting technology, and end point carbon is controlled at 0.30%-0.70%, so both can reduce the carburelant consumption, reduces production costs, and can reach the minimizing inclusion content of steel again, improves the purpose of molten steel purity;

3, refinery practice control, concerning the production of cord steel, the purified main purpose is exactly the removal of inclusion, by the requirement of cord steel to inclusion, greater than necessary removal of being mingled with of 20 μ m, thereby draw definite LF refining furnace refining time of the removal time that is mingled with greater than 20 μ m by Theoretical Calculation;

4, continuous casting production process has reduced two cold-zone induction stirring and terminal induction stirring.By the control of tundish superheating temperature and secondary cooling intensity, can produce and satisfy the qualified strand that cord steel requires, reduced continuously cast bloom reconditioning operation;

5, the pairing continuously cast bloom cross dimensions of the present invention is: 150 * 150mm ², can be directly being rolled into the cross dimensions that cord steel requires by high-speed rod-rolling mill is φ 5.5mm wire rod.Reduce secondary cogging and steel blank regrinding operation, reduced production cost.

Other advantages of the present invention, target and feature will be set forth to a certain extent in the following description, and to a certain extent, based on being conspicuous to those skilled in the art, perhaps can obtain instruction from the practice of the present invention to investigating hereinafter.Target of the present invention and other advantages can realize and obtain by specifically noted structure in following specification sheets or the accompanying drawing.

Embodiment

The present invention will be further described below in conjunction with embodiment:

Is example with existing production cord with steel LX70A technology, and production unit mainly contains: 900 tons of hot metal mixer, desulfurizing iron pretreatment unit, 100 tons of converters, 100 tons of uhp electric arc furnaces, 100 tons of LF refining furnaces, 100 tons of VD vacuum-treat stoves, R8m billet caster, crystallizer induction stirring and terminal induction stirring, high-speed rod-rolling mill.

Cord of the present invention with the steel LX70A technological process of production is:

---the R8m billet caster is cast 150 * 150mm to 900 tons of hot metal mixer in 100 tons of converters---100 tons of LF ladle refining furnaces--- ²---the high-speed rod unit is rolling---weighing---puts in storage strand.

1, ingredient requirement:

Molten iron: directly adopt blast furnace or melten iron in hot-metal mixer to smelt, without hot metal pretreatment.Temperature 〉=1250 ℃; Composition: phosphorus≤0.100%; Sulphur≤0.050%; Titanium≤0.005%.

Steel scrap: adopt heavy or medium-sized steel scrap, must not use the steel scrap of impurity elements such as titaniferous, copper, zinc.

2, converter smelting:

At present both at home and abroad the producer of production cord steel all adopts " low catch carbon method " to produce, and promptly converter smelting endpoint carbon is controlled at 0.10-0.30%, use then carburelant carbon with addition of in claimed range.

The present invention adopts " high catch carbon " smelting technology, and end point carbon so both can reduce the carburelant consumption 0.30%～0.70%, reduced production costs, and can reach the minimizing inclusion content of steel again, improves the purpose of molten steel purity.

3, converter tapping control:

Add pre-top slag in the tapping process, the raw material of pre-top slag is: pre-melted slag or/and lime or/and fluorite;

In the tapping process, when tap reach total amount 2/3rds the time, in ladle, add silicocalcium or/and calsibar alloy or/and Si-Ba alloy or/and silicon carbide or/and calcium carbide, the pre-deoxidation of tapping.

4, refining furnace technology controlling and process

Adopt lime+fluorite to make refining slag, do not add other higher raw material of aluminium content, as bauxitic clay, with (Al in the control slag ₂O ₃) content is less than 10%, reduces brittle inclusion content in the steel.

The purified main purpose is a deoxidation alloying, composition fine setting, temperature adjustment, and the removal of inclusion.Concerning the production of cord steel, the purified main purpose is exactly the removal of inclusion, by the requirement of cord steel to inclusion, and greater than removing being mingled with of 20 μ m, therefore can be by the removal time that is mingled with greater than 20 μ m is determined LF refining furnace refining time.

The removal time that is mingled with greater than 20 μ m is determined:

When being mingled with size and being no more than 150 μ m, its ascent rate is obeyed Stokes'theorem:

V＝Kr ²

$k=\frac{2g({\mathrm{\ρ}}_m-{\mathrm{\ρ}}_s)}{9{\mathrm{\η}}_m}$

During steel liquid deoxidation, molten steel density p m=7.1g/cm ³

Inclusion density p s=3.0g/cm ³

Molten steel viscosity η m=0.05p

Then: V=44644r ²

When being mingled with when being 20 μ m, its ascent rate is: V=17.86mm/min

According to refining and continuous casting coupling is that refining time equated with the continuous casting time, the inclusion half-distance that in refining process, floats, and then refining time is:

L is the molten steel degree of depth in the ladle, and V is a different diameter inclusion floating speed.

By measures such as steel ladle bottom argon blowing, the weak churning time of increase, can promote inclusion further to float in addition, reach the purpose of pure molten steel.

The present invention is concerning the big-and-middle-sized smelting furnace more than 100 tons, and refining time was at 60～100 minutes.

5, continuous small-billet casting

Adopt the continuously cast bloom cross dimensions that the present invention produced to be: 150 * 150mm ²

(1) adopts the crystallizer induction stirring;

(2) continuous casting pulling rate: 2.0～2.6m/min.

Its quality of continuously cast bloom that adopts above explained hereafter to go out is:

Project	Center segregation	Center porosity	Central pipe
				Rank	??≤3	??≤3	??≤2

6, Rolling Production technology

Adopt the present invention, use 150 * 150mm ²Continuously cast bloom, directly being rolled into cross dimensions by high-speed rod-rolling mill is φ 5.5mm wire rod.

(1) start rolling temperature control: 970 ± 50 ℃;

(2) finishing mill temperature control: 900 ± 50 ℃;

(3) Stanermo wind-cooling linear control: entrance roller table speed: 38～60m/min; Outlet section roller table speed: 40～65m/min; Blower fan is opened the 1-8 platform, wherein, and 1-4 platform opening degree 80%-100%, 5-8 platform opening degree 60%-90%.

The φ 5.5mm cord steel wire rod that adopts the present invention to produce is produced through steel cord factory and to be used, and the result is: can produce φ 0.22mm-0.38mm monofilament: rough, in draw, carefully draw not fracture of wire; The steel cord produced behind plying: performance, completely the wheel rate is suitable with other factory's product.

Claims (5)

1. the production method of a cord steel comprises smelting, refining, and continuous casting and rolling is characterized in that: comprise the steps:

Step 1 adds raw material steel scrap and molten iron in converter;

Molten iron requires: molten iron temperature 〉=1250 ℃, and the content of phosphorus, sulphur, titanium (mass percent) is in the molten iron: phosphorus≤0.100%; Sulphur≤0.050%; Titanium≤0.005%;

Steel scrap requires: be the heavy or medium-sized steel scrap of titaniferous, copper, zinc impurity element not;

Step 2, converter smelting, end point carbon is controlled at 0.30%～0.70%;

Step 3, tapping control,

Add pre-top slag in the tapping process, the raw material of pre-top slag is: pre-melted slag or/and lime or/and fluorite;

In the tapping process, when tap reach total amount 2/3rds the time, in ladle, add silicocalcium or/and calsibar alloy or/and Si-Ba alloy or/and silicon carbide or/and calcium carbide;

Step 4, refining,

Make refining slag in the LF refining furnace, the raw material of refining slag is: lime is or/and fluorite is controlled (Al in the refining slag ₂O ₃) content is less than 10%;

Refining time is:

L is the molten steel degree of depth in the ladle, and V is a different diameter inclusion floating speed

Step 5, continuous small-billet casting, crystallizer induction stirring, continuous casting pulling rate: 2.0～2.6m/min;

Step 6, high-speed wire rolling is rolled into the cord steel wire rod by high-speed rod-rolling mill.

2. the production method of a kind of cord steel according to claim 1, it is characterized in that: in the described step 4, the refining time of the big-and-middle-sized smelting furnace more than 100 tons is 60～100min.

3. the production method of a kind of cord steel according to claim 1, it is characterized in that: in the described step 5, the continuously cast bloom cross dimensions of producing is: 150 * 150mm ²

4. the production method of a kind of cord steel according to claim 1 is characterized in that: in the described step 6,

Start rolling temperature control: 970 ± 50 ℃; Finishing mill temperature control: 900 ± 50 ℃;

Stanermo wind-cooling linear control: entrance roller table speed: 38～60m/min; Outlet section roller table speed: 40～65m/min;

Blower fan is opened 1～8, wherein 1～4 typhoon machine opening degree, 80%～100%, 5～8 typhoon machine opening degrees 60%～90%.

5. according to the production method of claim 1 or 4 described a kind of cord steel, it is characterized in that: described cord steel wire rod cross dimensions is φ 5.5mm, and sorbite content reaches more than 85% in the described cord steel wire rod.