Production method for controlling scabbing of low-carbon wire drawing material

Abstract

The invention discloses a production method for controlling scabbing of a low-carbon wire drawing material, which comprises the following steps of: (1) controlling the end-point oxygen concentration to be less than or equal to 600ppm and the end-point carbon content to be 0.035-0.060% in converter smelting; (2) refining operation slag deoxidation and molten steel deoxidation are carried out synchronously, the Mn / S ratio is controlled to be larger than 13 in the refining stage, and the refining outbound oxygen concentration is 8-40 ppm; (3) in the continuous casting stage, the vibration mark depth is controlled to be 0.7-1.2 mm, the vibration mark interval is controlled to be 15-20 mm, and the over-withdrawal and straightening temperature of a casting blank is higher than 1050 DEG C; and (4) in the rolling stage, high-pressure water is adopted for descaling, and the descaling pressure is larger than 18 MPa. The surface quality of the steel billet is controlled, qualified raw materials are provided for the next procedure, the rolling procedure is improved, oxide scales on the surface of the casting billet of the heating furnace are cleaned, and the scabbing problem occurring in the production process of the low-carbon wire drawing material is controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of steelmaking, in particular to a method for controlling the production of scarred low-carbon wire drawing materials. Background Art

[0002] In the existing production process of low-carbon wire drawing materials, due to their functional characteristics, high requirements are imposed on their surface quality. Low-carbon wire drawing materials are often used to manufacture products such as galvanized steel wires and welding wires. In subsequent processing and use, any surface defects may affect the quality and performance of the final product. During the production process, even tiny defects such as scars and cracks, conventional production parameters, inclusions and gas content in the molten steel will directly affect the quality of the steel. The surface quality of the continuous casting billet is unstable, there is slag accumulation at the end of the continuous casting billet or slag on the rolling rolls during the rolling process, and there are problems such as blisters and pinholes in the subcutaneous tissue of the continuous casting billet, resulting in internal defects such as pores and looseness, reducing the strength and toughness of the steel, and various types of scars will appear on the surface of the steel, thus affecting the use effect, and generally it will be scrapped or downgraded. Summary of the Invention

[0003] In order to overcome the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method for controlling the production of scarred low-carbon wire drawing materials by improving the cleanliness of molten steel, improving the internal and external quality of continuous casting billets, providing qualified raw materials for rolling, controlling the rolling process, and reducing the number of scars.

[0004] The technical solution adopted by the present invention to solve its technical problems is: a method for controlling the production of scarred low-carbon wire drawing materials, comprising the following steps:

[0005] (1) In the converter smelting, control the end-point oxygen concentration ≤ 600 ppm, and control the end-point carbon content at 0.035% - 0.060%;

[0006] (2) In the refining operation, slag deoxidation and molten steel deoxidation are carried out simultaneously. Control the Mn / S ratio to be greater than 13 in the refining stage, and the oxygen concentration at the end of refining is 8 - 40 ppm;

[0007] (3) In the continuous casting stage, control the oscillation mark depth to be 0.7 - 1.2 mm, the oscillation mark spacing to be 15 - 20 mm, and the temperature of the continuous casting billet after the straightening machine is > 1050 °C;

[0008] (4) In the rolling stage, use high-pressure water descaling, and the descaling pressure > 18 MPa.

[0009] As a further improvement of the present invention: in the step (2), the residence time in the refining station > 15 min, and the soft blowing time > 5 min after the molten steel purification treatment is completed.

[0010] As a further improvement of the present invention: in the step (2), after deoxidation alloying, calcium carbide or raw dolomite powder is added for top slag pre-deoxidation, and the slag layer thickness is controlled to be 10 - 30 mm.

[0011] As a further improvement of the present invention: in the step (3), the superheat of molten steel in the continuous casting tundish is 20-30°C, the basicity of the mold powder is >0.9, and the slag consumption is >0.28 kg / t.

[0012] As a further improvement of the present invention: in the step (3), the continuous casting billet is cut by a flame cutting mode, and the cutting slag is cleaned up after cutting and recycled for the steel rolling process.

[0013] As a further improvement of the present invention: in the step (1), after tapping from the converter, aluminum-manganese iron particles are added into the ladle to strengthen the deoxidation of the slag.

[0014] As a further improvement of the present invention: in the step (1), the addition amount of high-rate aluminum-manganese iron is controlled at 3.15-3.20 Kg / t, and the refining oxygen entering the station is <100 PPm.

[0015] As a further improvement of the present invention: in the step (1), the viscosity of the top slag is 0.02-0.10 Pa·s.

[0016] As a further improvement of the present invention: in the step (3), the liquid level fluctuation of the continuous casting mold is controlled ≤10 mm, the specific water ratio is ≤1.68, and there is no accumulation of cutting slag at the head and tail of the steel billet.

[0017] As a further improvement of the present invention: in the step (4), the water flow rate of the high-pressure water descaling device is 20-25 m / s, and the nozzle angle is 30°-45°.

[0018] As a further improvement of the present invention: in the step (4), after descaling, it is controlled that there is no slag accumulation and burrs on the discharge roller table, and the surface roughness Ra of the roller table is ≤0.8 μm.

[0019] As a further improvement of the present invention: in the step (3), the continuous casting billet is cooled by a gradient controlled cooling process, and the cooling rate is 10-15°C / min.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] The present invention provides a method for controlling the scarring of low-carbon drawn wire. By controlling the key parameters of the converter, the inclusions in the molten steel are reduced, the cleanliness of the molten steel is improved, the internal inclusions of the cast billet are reduced, the key parameters of refining are controlled to ensure the uniformity of the molten steel, fully promote the floating of inclusions, ensure the cleanliness of the molten steel, control the surface quality of the steel billet, provide qualified raw materials for the next process, improve the rolling process, clean the scale on the surface of the cast billet in the heating furnace, and control the scarring problem that appears in the production process of low-carbon drawn wire. Description of the Drawings

[0022] Figure 1This is a structural schematic diagram of the present invention. Specific Embodiments

[0023] To clearly and completely understand the technical solution, the present invention will be further described below in conjunction with embodiments and the accompanying drawings. Obviously, the described embodiments are only partial embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention.

[0024] It should be understood that when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0025] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in this specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0026] It should be further understood that the term "and / or" used in this specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0027] An embodiment of the present invention provides a method for controlling the production of scars on low-carbon drawn wire, including the following steps:

[0028] (1) In the converter smelting, control the end-point oxygen concentration ≤ 600 ppm, and control the end-point carbon content at 0.035% - 0.060%;

[0029] (2) In the refining operation, slag deoxidation and molten steel deoxidation are carried out simultaneously. Control the Mn / S ratio to be greater than 13 in the refining stage, and the oxygen concentration at the end of refining is 8 - 40 ppm;

[0030] (3) In the continuous casting stage, control the oscillation mark depth to be 0.7 - 1.2 mm, the oscillation mark spacing to be 15 - 20 mm, and the temperature of the continuously cast slab after the straightening machine > 1050 °C;

[0031] (4) In the rolling stage, use high-pressure water descaling, and the descaling pressure > 18 MPa.

[0032] This embodiment provides a method for controlling the scarring of low-carbon drawn wire. By controlling the key parameters of the converter, the inclusions in the molten steel are reduced, the cleanliness of the molten steel is improved, the internal inclusions in the continuous casting billet are reduced, the key parameters of refining are controlled to ensure the uniformity of the molten steel, the floating of inclusions is fully promoted, the cleanliness of the molten steel is ensured, the surface quality of the steel billet is controlled, qualified raw materials are provided for the next process, the rolling process is improved, the scale on the surface of the continuous casting billet in the heating furnace is cleaned, and the scarring problem occurring in the production process of low-carbon drawn wire is controlled. According to the method for controlling the production of low-carbon drawn wire with scars in this application, by integrating and optimizing the process parameters of the four key processes of converter smelting, refining, continuous casting, and rolling, the scarring rate can be reduced, the cleanliness of the molten steel can be improved, the surface quality of the continuous casting billet can be improved, and the rolling finished product rate can be stabilized. The converter smelting controls the end-point oxygen concentration ≤ 600 ppm, the end-point carbon content ≥ 0.035%, the oxygen concentration at the entrance of refining < 120 ppm, compared with the conventional process > 200 ppm, the dosage of deoxidizer is reduced by 20%, the initial oxygen content of the molten steel is reduced, the generation of oxide inclusions is inhibited, and a low-oxygen molten steel basis is provided for subsequent refining. The Mn / S ratio is greater than 13, the generation of sulfide inclusions is inhibited, the crack resistance of the steel billet is improved, and the oxygen concentration at the exit of refining is 8 - 40 ppm, which can ensure the cleanliness of the molten steel. In the continuous casting stage, the oscillation mark parameters are controlled, the oscillation mark depth is 0.7 - 1.2 mm, the oscillation mark spacing is 15 - 20 mm, the balance between lubrication and stress distribution is achieved, subcutaneous cracks are reduced, and the over-drawing and straightening temperature of the continuous casting billet > 1050 °C can release the internal stress of the continuous casting billet and inhibit crack propagation.

[0033] In the refining stage, the Mn / S ratio is controlled to be greater than 13. The Mn element can inhibit the formation of sulfide inclusions. Increasing the Mn / S ratio can refine the size of sulfide inclusions and improve the distribution, thereby reducing stress concentration and crack sources.

[0034] The descaling pressure > 18 MPa, reducing the surface defects caused by the extrusion of residues during rolling. By treating the surface cleanliness of the steel, the surface quality of the rolled steel is directly improved.

[0035] In an implementation manner of this embodiment, in the step (1), after the converter taps steel, aluminum-manganese iron pellets are added into the ladle to strengthen the deoxidation of the slag.

[0036] Furthermore, the addition amount of high-rate aluminum-manganese iron is controlled at 3.15 - 3.20 Kg / t, and the oxygen at the entrance of refining < 100 PPm.

[0037] In this embodiment, aluminum-manganese iron can be used as a deoxidizer, which can undergo an oxidation reaction in the molten steel to reduce the oxygen content of the molten steel.

[0038] In step (1), the viscosity of the top slag is 0.02-0.10 Pa·s. Since the viscosity of the top slag affects the deoxidation efficiency of the molten steel and the inclusion removal rate, too low viscosity results in an unstable slag layer, and too high viscosity will hinder the slag-steel reaction. Further, when the viscosity of the top slag is 0.05-0.10 Pa·s, within this range, the deoxidation efficiency and the inclusion removal rate can be improved.

[0039] In an embodiment of this example, in step (2), the refining time in the station > 15 min, and the soft blowing time > 5 min after the molten steel purification treatment is completed. After deoxidation alloying, calcium carbide or raw dolomite powder is added for pre-deoxidation of the top slag, and the thickness of the slag layer is controlled to be 10-30 mm.

[0040] In this example, the deoxidizer is added batch by batch at intervals to ensure sufficient reaction and avoid temperature fluctuations caused by concentrated heat release; the argon flow rate is adjusted in three stages of "pre-blowing → normal refining → soft blowing", the stirring time is extended, the slag amount and alkalinity are controlled, the fluidity of the slag layer is maintained, and desulfurization and inclusion adsorption are promoted; calcium carbide and raw dolomite powder decompose at high temperatures to generate CaO and MgO, which react with the dissolved oxygen in the molten steel to form stable oxides, further reducing the oxygen concentration in the molten steel to 8-40 ppm. CaO combines with sulfur in the molten steel to form CaS, which floats up through slag phase adsorption to achieve deep desulfurization. The refining time in the station > 15 min. Extending the refining time in the station can fully complete the diffusion deoxidation reaction of the deoxidizer, promote the formation and floating of sulfides, and long-term bottom blowing argon stirring accelerates the collision, aggregation and floating of non-metallic inclusions, and the inclusion removal rate can reach more than 90%; the soft blowing time > 5 min after the molten steel purification treatment is completed. After refining, continuous soft blowing of argon forms an inert gas covering layer to isolate the air and avoid secondary oxidation of the molten steel; when the thickness of the slag layer is 10-30 mm, the slag viscosity can be stabilized within the range of 0.02-0.10 Pa·s, ensuring moderate fluidity of the slag layer, effectively adsorbing inclusions, avoiding excessive entrainment of molten steel, and at the same time, an appropriate thickness of the slag layer forms a physical barrier, reducing secondary oxidation of the molten steel and slowing down the temperature drop of the molten steel.

[0041] In an embodiment of this example, in step (3), the superheat of the molten steel in the continuous casting tundish is 20-30 °C, the basicity of the mold powder > 0.9, and the slag consumption > 0.28 kg / t. In this example, the superheat of the molten steel can adjust the fluidity and solidification rate of the molten steel, thereby inhibiting subcutaneous pores and cracks. Increasing the basicity of the slag in the mold can improve the lubricity of the slag layer, adsorb inclusions, and reduce the depth of the oscillation marks on the surface of the casting billet; increasing the slag consumption ensures uniform coverage of the casting billet with the slag film, reduces the friction between the casting billet and the mold, and avoids scratches on the casting billet.

[0042] In an embodiment of this example, in step (3), the continuous casting controls the liquid level fluctuation of the mold ≤ 10 mm, the specific water volume ≤ 1.68, and there is no accumulation of cutting slag at the head and tail of the steel billet.

[0043] In this embodiment, by adjusting the liquid level fluctuation in the mold, the fluctuation of the oscillation mark depth is reduced, the solidification process is stable, the surface finish after rolling is improved, the occurrence of shell cracks, subcutaneous pores and inclusions can be achieved. At the same time, the specific water volume is adjusted to enhance the cooling intensity, and there is no accumulation of cutting slag at both ends of the billet feeding, which can prevent the scale from being pressed into the surface of the rolled material, reduce the scar rate, and the coordinated control of the parameters in the mold reduces process abnormalities.

[0044] In an implementation manner of this embodiment, in the step (4), the water flow rate of the high-pressure water descaling device is 20 - 25 m / s, and the nozzle angle is 30° - 45°.

[0045] In this embodiment, the combined action of the water flow rate and the angle on the billet can improve the scale peeling efficiency. When the nozzle angle is 30° - 45°, there is a large shear force of the water flow on the surface of the steel, which improves the scale peeling efficiency.

[0046] In an implementation manner of this embodiment, in the step (4), after descaling, it is necessary to control that there is no slag accumulation and burrs on the discharge roller table, and the surface roughness Ra of the roller table is ≤ 0.8 μm. In this embodiment, no slag accumulation and burrs on the discharge roller table can avoid the adhesion of scale or metal debris on the surface of the rolled material, reduce scratches in subsequent rolling or deep processes, and the process should ensure that the surface of the roller table is smooth to prevent microcracks from being generated due to the friction between the roller table and the rolled material.

[0047] In an implementation manner of this embodiment, in the step (3), the continuous casting billet is cooled by a gradient controlled cooling process, and the cooling rate is 10 - 15 °C / min.

[0048] This embodiment balances the temperature difference between the core and the surface of the billet through gradient controlled cooling, avoids surface temper brittleness or scale thickening caused by uneven cooling, reduces the concentration of thermal stress, and reduces the crack rate inside the billet.

[0049] In the implementation manner of the present invention, the following problems exist in the prior art;

[0050] 1. The surface quality of the billet is unstable, and root-like scar problems caused by the billet are likely to occur;

[0051] 2. There is slag accumulation at the end of the billet or slag on the roll in the rolling process, and rootless scars are likely to occur;

[0052] 3. There are problems such as blisters and pinholes in the subcutaneous tissue of the billet, and root-like scars appear.

[0053] The object of the present invention is to provide a method for controlling the scarring of low-carbon drawn steel. By controlling the key parameters of the converter, the inclusions in the molten steel are reduced, the cleanliness of the molten steel is improved, the internal inclusions of the continuous casting billet are reduced, the key parameters of the refining are controlled to ensure the uniformity of the molten steel, fully promote the floating of inclusions, ensure the cleanliness of the molten steel, control the surface quality of the steel billet, provide qualified raw materials for the next process, improve the rolling process, clean the scale on the surface of the continuous casting billet in the heating furnace, and control the scarring problem occurring in the production process of low-carbon drawn steel.

[0054] Working process of this embodiment (key parameter control)

[0055] 1. Key parameters of converter control. The endpoint oxygen is controlled below 600PPm, the endpoint C is controlled at 0.035% - 0.060%, the addition amount of high-rate ferromanganese aluminum is controlled according to 3.15 - 3.20 Kg / t, and the incoming station refining oxygen < 100PPm. The purpose of this key control parameter is to reduce the inclusions in the molten steel, improve the quality of the molten steel, and reduce the subcutaneous pores of the continuous casting billet.

[0056] 2. The residence time in the refining station needs to be greater than 15 min, the soft blowing time needs to be greater than 5 min after the purification treatment of the molten steel is completed, the refining operation needs to carry out slag deoxidation and molten steel deoxidation synchronously, and the refining outgoing oxygen needs to be controlled at 8 - 40PPm. The purpose of this key control parameter is to ensure the uniformity of the molten steel, fully promote the floating of inclusions, and ensure the cleanliness of the molten steel.

[0057] 3. Composition control: The Mn / S ratio is greater than 13. The purpose of this design is to improve the crack resistance sensitivity of the steel billet and meet the machinability.

[0058] The content of each material of the low-carbon drawn steel is shown in Table 1.

[0059] Table 1

[0060] Standard C，％ Si, % Mn, % P，％ S，％ Judgment ≤0.12 ≤0.20 ≤0.55 ≤0.035 ≤0.040 Internal control 0.04-0.06 0.02-0.06 0.15-0.30 ≤0.020 ≤0.020

[0061] 4. Continuous casting control parameters: The liquid level fluctuation in the mold ≤ 10 mm, the oscillation mark depth 0.7 - 1.2 mm, the oscillation mark spacing 15 - 20 mm, the specific water volume ≤ 1.68, and there shall be no obvious accumulation of cutting slag at the head and tail of the steel billet. The temperature of the continuous casting billet passing through the straightening machine > 1050 °C. The basicity of the mold powder > 0.9, and the consumption of the slag > 0.28 kg / t. The purpose of controlling the key parameters of continuous casting is to ensure the surface quality of the continuous casting billet, prevent rolling cracks, subcutaneous cracks and corner cracks, and improve the surface quality of the continuous casting billet.

[0062] The main purpose of the above key measures is to provide high-quality continuous casting billets for the rolling process and control the root scarring.

[0063] 5. Rolling process: The high-pressure water descaling pressure > 18 MPa. The purpose is to clean the scale, mold powder and cutting slag on the surface of the continuous casting billet in the heating furnace and control the root-like scarring.

[0064] In summary, after reading the present invention document, those of ordinary skill in the art can make various other corresponding transformation schemes without creative mental labor according to the technical solutions and technical concepts of the present invention, and all of them fall within the scope protected by the present invention.

Claims

1. A production method for controlling the formation of scars on low-carbon drawn wire, characterized in that, It includes the following steps: (1) In the converter smelting, control the final oxygen concentration ≤ 600 ppm, and control the final carbon content at 0.035% - 0.060%; (2) In the refining operation, slag deoxidation and molten steel deoxidation are carried out simultaneously. Control the Mn / S ratio to be greater than 13 in the refining stage, and the oxygen concentration at the end of refining is 8 - 40 ppm; (3) In the continuous casting stage, control the oscillation mark depth to be 0.7 - 1.2 mm, the oscillation mark spacing to be 15 - 20 mm, and the temperature of the slab after the straightening machine > 1050 °C; (4) In the rolling stage, use high-pressure water descaling, and the descaling pressure > 18 MPa.

2. According to a method for controlling the production of scars on low-carbon drawn wires described in claim 1, in the step (2), the residence time in the station during refining > 15 min, and the soft blowing time > 5 min after the purification treatment of the molten steel is completed.

3. In the step (2), after deoxidation alloying, add calcium carbide or raw dolomite powder for top slag pre-deoxidation, and control the slag layer thickness to be 10 - 30 mm.

4. According to a method for controlling the production of scars on low-carbon drawn wires described in claim 1, in the step (3), the superheat of the molten steel in the tundish during continuous casting is 20 - 30 °C, the basicity of the mold powder > 0.9, and the consumption of the slag > 0.28 kg / t.

5. According to a method for controlling the production of scars on low-carbon drawn wires described in claim 1, in the step (1), after tapping from the converter, add aluminum-manganese iron particles into the ladle to strengthen the deoxidation of the slag.

6. According to a method for controlling the production of scars on low-carbon drawn wires described in claim 1, in the step (1), the addition amount of high-rate aluminum-manganese iron is controlled at 3.15 - 3.20 Kg / t, and the oxygen content at the entrance of refining < 100 PPm.

7. According to a method for controlling the production of scars on low-carbon drawn wires described in claim 1, the viscosity of the top slag is 0.02 - 0.10 Pa·s.

8. According to a method for controlling the production of scars on low-carbon drawn wires described in claim 1, in continuous casting, control the liquid level fluctuation in the mold ≤ 10 mm, the specific water volume ≤ 1.68, and there is no accumulation of cutting slag at the head and tail of the steel billet.

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