Cord steel and manufacturing method thereof

Abstract

The embodiment of the invention provides tire cord steel and a manufacturing method thereof. The tire cord steel comprises, by mass, 0.825%-0.845% of C, 0.17%-0.21% of Si, 0.50%-0.54% of Mn, smaller than or equal to 0.018% of P, smaller than or equal to 0.010% of S, 0.04% of Cr, smaller than or equal to 0.04% of Ni, smaller than or equal to 0.05% of Cu, 0.01% of Mo, smaller than or equal to 0.0010% of Ti, smaller than or equal to 0.0020% of AL, smaller than or equal to 0.0045% of N, smaller than or equal to 0.007% of Sn and the balance iron and inevitable impurity elements. The inclusion in the wire rod comprises the following components in percentage by mass: 5-15% of Al2O3, 3-15% of MgO, less than or equal to 0.05% of TiN, less than or equal to 0.05% of TiO2, less than or equal to 0.5% of CaS, less than or equal to 4% of MnO, 39-47% of SiO2 and 36-45% of CaO. The manufacturing cost of the tire cord steel is low.

Description

Technical Field

[0001] The present invention relates to the field of metallurgy, and in particular to a cord steel and a manufacturing method thereof. Background Art

[0002] Cord steel products are usually used in automobile tires as radial wires. The wire drawing diameter reaches 0.17mm. The wire breakage in 10,000 meters is generally required to be no more than 3 times. In order to achieve this standard, steel mills often use high-quality and high-priced clean raw and auxiliary alloys. Solving the high cost is a technical problem that the steel industry is generally facing today, especially the cord steel product wire rod Al 2 O 3 Component content control, high Al 2 O 3 The number of inclusions, the frequency of wire breakage during drawing process, low Al 2 O 3 The content component rolling plasticity ability is insufficient and the inclusion size exceeds the standard. Summary of the invention

[0003] The embodiment of the present invention provides a cord steel and a manufacturing method thereof, so as to at least solve the problem of high cost in the related art.

[0004] According to the invention, the cord steel has the following components in percentage by mass: C: 0.825-0.845%, Si: 0.17-0.21%, Mn: 0.50-0.54%, P: ≤0.018%, S: ≤0.010%, Cr: 0.04%, Ni: ≤0.04%, Cu: ≤0.05%, Mo: 0.01%, Ti: ≤0.0010%, Al: ≤0.0020%, N: ≤0.0045%, Sn: ≤0.007%, and the rest are iron and unavoidable impurity elements; The composition of inclusions in the wire rod is as follows: Al 2 O 3 : 5~15%, MgO: 3~15%, TiN: ≤0.05%, TiO 2 : ≤0.05%, CaS: ≤0.5%, MnO: ≤4%, SiO 2 :39~47%, CaO: 36~45%.

[0005] Further, the steps include: (1) KR mechanical stirring desulfurization treatment of molten iron; (2) Perform converter smelting, add ferrosilicon during the converter steel alloying process, and the ferrosilicon contains 1.0-1.8% Al by mass; (3) LF refining station receives the cord steel molten steel for further refining and smelting, so that the chemical composition of the molten steel meets the following requirements: C: 0.825~0.845%, Si: 0.17~0.21%, Mn: 0.50~0.54%, P: ≤0.018%, S: ≤0.010%, Cr: 0.04%, Ni: ≤0.04%, Cu: ≤0.05%, Mo: 0.01%, Ti: ≤0.0010%, Al: ≤0.0020%, N: ≤0.0045%, Sn: ≤0.007%; (4) Continuous casting protection pouring; (5) Cord steel forming.

[0006] Furthermore, in step (2), the ferrosilicon components are as follows by mass percentage: Si: 72-75%, C: ≤0.2%, Mn: ≤0.4%, P: ≤0.04%, S: ≤0.02%, Al: 1.0-1.8%, Cr: ≤0.3%, Ti: ≤0.3%.

[0007] Furthermore, in step (2), ferrosilicon is added to reduce the Al content in the refined slag. 2 O 3 The mass fraction is above 4%; the amount of lime added at the end of the converter is controlled to make the Al content in the refined slag 2 O 3 The mass fraction is 4~7%.

[0008] Furthermore, the converter endpoint controls overoxidation so that the endpoint oxygen content is less than 900 ppm.

[0009] Furthermore, in step (3), the Al in the inclusions is reacted with the slag metal to form 2 O 3 The quality fraction is controlled at 5-15%.

[0010] Furthermore, in step (2), clean scrap steel is added to the converter and molten iron that has been desulfurized and meets the requirements of cord steel is added to perform converter smelting.

[0011] Furthermore, in step (3), the time from the completion of LF refining and the addition of synthetic slag to the start of soft stirring is ≥45 min; and the soft stirring time of LF refining is ≥15 min.

[0012] Furthermore, in step (4), the continuous casting protective pouring adopts a large ladle with a long nozzle and argon seal, a tundish covering agent, and an integral nozzle for full protection pouring. Before pouring, an argon blowing pipe is used to remove the air in the tundish. The lower end of the argon blowing pipe is 400-500mm away from the bottom of the tundish. Argon is blown until the covering agent is added. The liquid level of the tundish is controlled to be ≥30t for the start of pouring, ≥35t for the tundish during normal pouring, and ≥30t for the tundish during continuous casting and changing ladles. The large ladle is operated with steel retention, and the amount of steel retained is ≥2t.

[0013] Furthermore, step (5) includes: stretching the cord steel wire rod - peeling - heat treatment wire drawing - cold drawing Φ0.3~0.15mm - stranding.

[0014] Beneficial effect: Compared with the existing technology, this technical method uses ordinary ferrosilicon instead of high-quality, high-priced, low-titanium, low-aluminum ferrosilicon to deoxidize and alloy the molten steel during the steelmaking process of cord steel products, and controls the reasonable Al 2 O 3 The component content reduces the cost of steelmaking alloys and improves production efficiency. In the past, the alloying of cord steel converter steel used high-quality and high-priced clean raw and auxiliary alloys, one of which is ultra-low titanium and low aluminum ferrosilicon. This technical invention uses ordinary ferrosilicon instead of high-quality and high-priced low titanium and low aluminum ferrosilicon for deoxidation and alloying of molten steel in converter steel, and uses the Al content in ordinary ferrosilicon to reduce the Al in the slag. 2 O 3 The content of the component is controlled at 4-7%. The steelmaking alloying method of this process is used to remove inclusions in conjunction with argon stirring to control the reasonable Al content in the wire. 2 O 3 The content of the component becomes more and more important. This patent provides a technical method for using ordinary ferrosilicon to replace ultra-low titanium and low aluminum ferrosilicon in cord steel, and timely improves the Al content in refined slag. 2 O 3 Component content, and then through the slag-metal reaction, the Al in the inclusions 2 O 3 The content is controlled at 5-15%, increasing the CaO-SiO 2 -Al 2 O 3 The deformation ability of inclusions is improved, the size of inclusions does not exceed the standard, the broken wires in 10,000 meters of wire rod drawing do not exceed the standard, the production efficiency is improved, the use of high-quality alloys for cord steel is significantly improved and reduced, and the production cost is directly and indirectly reduced. It is calculated that the cost of smelting ferrosilicon for cord steel by using the technology of the present invention can be reduced by about 1.9 yuan / t. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 It is a schematic diagram of the principle of an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0017] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0018] See also Figure 1 , an embodiment of the present invention provides a cord steel, the components of the cord steel are as follows by mass percentage: C: 0.825-0.845%, Si: 0.17-0.21%, Mn: 0.50-0.54%, P: ≤0.018%, S: ≤0.010%, Cr: 0.04%, Ni: ≤0.04%, Cu: ≤0.05%, Mo: 0.01%, Ti: ≤0.0010%, Al: ≤0.0020%, N: ≤0.0045%, Sn: ≤0.007%, and the rest are iron and unavoidable impurity elements; The composition of inclusions in the wire rod is as follows: Al 2 O 3 : 5~15%, MgO: 3~15%, TiN: ≤0.05%, TiO 2 : ≤0.05%, CaS: ≤0.5%, MnO: ≤4%, SiO 2 :39~47%, CaO: 36~45%.

[0019] Further, the steps include: (1) Perform KR mechanical stirring desulfurization treatment on molten iron to make the mass percentage of S in the molten iron ≤0.005%; (2) Perform converter smelting, and add ferrosilicon (200-350 kg) during the converter steel alloying process, wherein the ferrosilicon contains 1.0-1.8% Al by mass; (3) LF refining station receives the cord steel molten steel for further refining and smelting, so that the chemical composition of the molten steel meets the following requirements: C: 0.825~0.845%, Si: 0.17~0.21%, Mn: 0.50~0.54%, P: ≤0.018%, S: ≤0.010%, Cr: 0.04%, Ni: ≤0.04%, Cu: ≤0.05%, Mo: 0.01%, Ti: ≤0.0010%, Al: ≤0.0020%, N: ≤0.0045%, Sn: ≤0.007%; (4) Continuous casting protection pouring; (5) Cord steel forming.

[0020] Furthermore, in step (2), the ferrosilicon components are as follows by mass percentage: Si: 72-75%, C: ≤0.2%, Mn: ≤0.4%, P: ≤0.04%, S: ≤0.02%, Al: 1.0-1.8%, Cr: ≤0.3%, Ti: ≤0.3%.

[0021] Furthermore, in step (2), ferrosilicon is added to reduce the Al content in the refined slag. 2 O 3 The mass fraction is above 4%; the amount of lime added at the end of the converter is controlled to make the Al content in the refined slag 2 O 3 The mass fraction is 4~7%.

[0022] Furthermore, the converter endpoint controls overoxidation so that the endpoint oxygen content is less than 900 ppm.

[0023] Furthermore, in step (3), the Al in the inclusions is reduced by slag-metal reaction (the refined molten steel is heated by electricity, and the bottom blowing argon gas stirring is combined to further promote the reduction reaction of the refined slag). 2 O 3 The quality fraction is controlled at 5-15%.

[0024] Furthermore, in step (2), clean scrap steel is added to the converter and molten iron that has been desulfurized and meets the requirements of cord steel is added to perform converter smelting.

[0025] Furthermore, in step (3), the time from the addition of synthetic slag (synthetic slag 1400 kg) to the start of soft stirring in LF refining is ≥ 45 min; the soft stirring time in LF refining is ≥ 15 min.

[0026] Furthermore, in step (4), the continuous casting protective pouring adopts a large ladle with a long nozzle and argon seal, a tundish covering agent, and an integral nozzle for full protection pouring. Before pouring, an argon blowing pipe is used to remove the air in the tundish. The lower end of the argon blowing pipe is 400-500mm away from the bottom of the tundish. Argon is blown until the covering agent is added. The liquid level of the tundish is controlled to be ≥30t for the start of pouring, ≥35t for the tundish during normal pouring, and ≥30t for the tundish during continuous casting and changing ladles. The large ladle is operated with steel retention, and the amount of steel retained is ≥2t.

[0027] Furthermore, step (5) includes: stretching the cord steel wire rod - peeling - heat treatment wire drawing - cold drawing Φ0.3~0.15mm - stranding.

[0028] The method of using ordinary ferrosilicon alloying in this embodiment includes: (1) The Al content in ordinary ferrosilicon is confirmed by inspection, AL=1.0~1.8%; (2) Optimize and improve the converter steel alloying process, and use ordinary ferrosilicon to increase the content of AL2O3 components in LF refined slag to more than 4%; (3) Optimize and improve the converter endpoint control, control overoxidation, and appropriately add lime in an amount of about 200 kg to further increase the content of AL2O3 components in the refined slag and stabilize it within the range; (4) At the same time, through the slag-metal reaction, the Al2O3 content in the inclusions is controlled at 5-15%, the deformation capacity of CaO-SiO2-AL2O3 inclusions is improved, the inclusion size does not exceed the standard (≤35μm), and the wire breakage of 10,000 meters of wire rod drawing does not exceed the standard.

[0029] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A cord steel, characterized in that: The composition of the cord steel is as follows by mass percentage: C: 0.825-0.845%, Si: 0.17-0.21%, Mn: 0.50-0.54%, P: ≤0.018%, S: ≤0.010%, Cr: 0.04%, Ni: ≤0.04%, Cu: ≤0.05%, Mo: 0.01%, Ti: ≤0.0010%, Al: ≤0.0020%, N: ≤0.0045%, Sn: ≤0.007%, and the rest are iron and unavoidable impurity elements; The components of inclusions in the wire rod are as follows by mass percentage: Al2O3: 5~15%, MgO: 3~15%, TiN: ≤0.05%, TiO2: ≤0.05%, CaS: ≤0.5%, MnO: ≤4%, SiO2: 39~47%, CaO: 36~45%.

2. A method for manufacturing a cord steel according to claim 1, characterized in that: Includes steps: (1) KR mechanical stirring desulfurization treatment of molten iron; (2) Perform converter smelting, add ferrosilicon during the converter steel alloying process, and the ferrosilicon contains 1.0-1.8% Al by mass; (3) LF refining station receives the cord steel molten steel for further refining and smelting, so that the chemical composition of the molten steel meets the following requirements: C: 0.825~0.845%, Si: 0.17~0.21%, Mn: 0.50~0.54%, P: ≤0.018%, S: ≤0.010%, Cr: 0.04%, Ni: ≤0.04%, Cu: ≤0.05%, Mo: 0.01%, Ti: ≤0.0010%, Al: ≤0.0020%, N: ≤0.0045%, Sn: ≤0.007%; (4) Continuous casting protection pouring; (5) Cord steel forming.

3. The method for manufacturing cord steel according to claim 2, characterized in that: In step (2), the ferrosilicon components are as follows by mass percentage: Si: 72-75%, C: ≤0.2%, Mn: ≤0.4%, P: ≤0.04%, S: ≤0.02%, Al: 1.0-1.8%, Cr: ≤0.3%, Ti: ≤0.3%.

4. The method for manufacturing cord steel according to claim 3, characterized in that: In step (2), ferrosilicon is added to make the mass fraction of Al2O3 in the refined slag greater than 4%; at the end of the converter, the mass fraction of Al2O3 in the refined slag is controlled to be 4-7%.

5. The method for manufacturing cord steel according to claim 4, characterized in that: The converter endpoint controls overoxidation so that the endpoint oxygen content is less than 900ppm.

6. The method for manufacturing cord steel according to claim 5, characterized in that: In step (3), the mass fraction of Al2O3 in the inclusions is controlled to be 5-15% through slag-metal reaction.

7. The method for manufacturing cord steel according to claim 2, characterized in that: In step (2), clean scrap steel is added to the converter and molten iron that has been desulfurized and meets the requirements of cord steel is added to perform converter smelting.

8. The method for manufacturing the cord steel according to claim 2, characterized in that: In step (3), the time from the completion of adding synthetic slag to the start of soft stirring in LF refining is ≥45min; the soft stirring time in LF refining is ≥15min.

9. The method for manufacturing cord steel according to claim 2, characterized in that: In step (4), the continuous casting protective pouring adopts a large ladle with a long nozzle and argon seal, a tundish covering agent, and an integral nozzle for full protective pouring. Before pouring, an argon blowing pipe is used to remove the air in the tundish. The lower end of the argon blowing pipe is 400-500mm away from the bottom of the tundish. Argon is blown until the covering agent is added. The liquid level of the tundish is controlled to be ≥30t for the start of pouring, ≥35t for the tundish during normal pouring, and ≥30t for the tundish tonnage during continuous casting and changing ladles. The large ladle is operated with steel retention, and the amount of steel retained is ≥2t.

10. The method for manufacturing cord steel according to claim 2, characterized in that: Step (5) includes: stretching the cord steel wire rod - peeling - heat treatment wire drawing - cold drawing Φ0.3~0.15mm - twisting.

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