High-carbon drawing material smelting production and wire rod structure regulation and control method

Abstract

The invention discloses a high-carbon drawing material smelting production and wire rod structure regulation and control method, which improves the cleanliness of steel through smelting, regulates and controls the structure of high-carbon steel and realizes smooth drawing of the high-carbon steel. According to the high-carbon drawing material smelting production and wire rod structure regulation and control method, by implementing the method, the drawing performance of high-carbon steel is improved, and drawing can be carried out smoothly.

Description

Technical Field

[0001] The invention belongs to the technical field of metal smelting and rolling technology, and in particular relates to a method for smelting and producing high-carbon drawn materials and regulating wire rod structure. Background Art

[0002] High carbon steel has high strength and has a wide range of applications. It is generally required to be drawn, and it needs to undergo large strain cold drawing to significantly improve the strength of high carbon steel drawn materials. During the drawing process, due to the dissolution of cementite and other reasons, high carbon steel drawn materials are prone to stratification; at the same time, factors such as poor wire surface quality, low purity of molten steel, and central segregation of continuous casting billets may also cause wire breakage. During the manufacturing process of high carbon steel drawn materials, it is necessary to pay attention to controlling the surface quality of the wire, the purity of the molten steel, and the drawing process parameters to ensure product quality and performance. In order to develop high carbon drawn materials, the above problems were improved and optimized. Through the smelting control of cleanliness and the regulation of the optimal structure of the wire rod, the supply of Baosteel drawn materials and the smooth drawing of users were finally achieved. Summary of the invention

[0003] The purpose of the present invention is to provide a method for smelting and producing high-carbon drawing materials and regulating the structure of wire rods, so as to solve the problem that Baosteel's high-carbon steel cannot be drawn, improve the cleanliness of the steel through smelting, regulate the structure of the high-carbon steel, and realize the smooth drawing of the high-carbon steel.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a method for smelting and producing high-carbon drawn materials and controlling the structure of wire rods, comprising:

[0006] Hot metal conditions for furnace entry: Si: 0.30-0.50%, S≤0.015%, P≤0.120%, Ti≤0.10%, T≥1250℃. The amount of slag should not exceed 0.5%. At the same time, residual elements are required to be controlled: Cr≤0.20%, Ni≤0.20%, Cu≤0.20%;

[0007] The converter adopts high carbon drawing process, the final composition of the steel is C ≥ 0.06%, P ≤ 0.020%, S ≤ 0.015%, C greater than 0.10% accounts for 80%, T: 1610 ~ 1630 ℃; the alloying sequence of converter steel is low nitrogen carburizer + ferrosilicon + silicon manganese or ferromanganese, converter top slag is added, and lime is added after the alloy is added;

[0008] LF refining operation requires opening the working door, adjusting the argon flow rate, and controlling the diameter of the blown area to about 300-400mm; after heating for 5 minutes, it is necessary to perform oxygen determination operation, and add 300kg of quartz sand and 50kg of small ash during the heating process; add 50kg of calcium carbide and 50kg of ferrosilicon powder intermittently during the heating process. After heating for 5 minutes, dip the slag to observe the white slag situation, and measure the temperature and take samples at the same time. According to the oxygen determination and slag situation, add 50kg of ferrosilicon powder. The deoxidizer is required to be sprinkled on the slag surface. After the next heating stops, dip the sample to observe the slag color. If it is transparent glass slag, it is considered that the white slag is made, otherwise continue to sprinkle the deoxidizer; the amount of alloy added is based on The internal control component requirements are adjusted; the heating time of the entire refining process is not less than 15 minutes, and the temperature measurement operation is carried out before the end of the treatment; the atmosphere in the ladle is guaranteed to be a reducing atmosphere during the entire refining process, and there is slight smoke during the heating process; if the sample sulfur is high, the amount of lime is increased during the heating process, and 0.002-0.003% desulfurization is considered for every 100kg of lime; after treatment, secondary heating due to other reasons must be re-slag making. If the ladle was used to produce aluminum-killed steel last time, calcium wire is fed for calcium treatment, and the wire feeding amount is controlled at 50-100m according to the length of heating time; the soft blowing time is more than 15min, and the molten steel must not be exposed during the soft blowing process. Covering agent use requirements R <2.0, FeO <1.0%;

[0009] In addition to the chemical composition meeting the above requirements, narrow component control is required, and the C content fluctuation range is 0.69%-0.71%; the continuous casting machine operation requires vibration: 190 times / min, amplitude 4mm; covering agent: use carbonized rice husk or low alkalinity covering agent; specific water volume is 0.8L / kg; the terminal electric stirring parameters implement the following experimental scheme; current 300A, frequency 8Hz experiment 1-2 heats; current 330A, frequency 8Hz experiment 1-2 heats; before continuous casting production, the crystallizer, foot roller and fan-shaped segment roller must be aligned and confirmed; the protective casing gas volume must be >4m 3 / h; atmosphere replacement pipeline and atmosphere replacement time must be confirmed on site;

[0010] The temperature of the first furnace is 35-55℃, and the pulling speed is controlled at 1.7-2.1m / min. The other furnaces are cast at a constant pulling speed, and the control target is 1.9m / min. The temperature control target of the tundish after the second furnace is 1497-1507℃, and the superheat of the furnace needs to be controlled at 20-30℃. When the tundish temperature is greater than 1512℃, the pulling speed is reduced to 1.8m / min. When the tundish temperature is less than 1497℃, the pulling speed is 2m / min, and other temperatures are 1.9m / min. The liquid level fluctuation is not allowed to exceed ±5mm, and the tundish liquid level height is ≥600mm;

[0011] The temperature of the heating section is 1100±20℃, the temperature of the soaking section is 1110±20℃, the tail of the billet is 20℃ higher than the head, the heating time is controlled at 120±15min, the residual oxygen is 1-4%; the number of billets out of the furnace is controlled at 35-45 billets / hour, 1# outlet temperature: 1020±20℃; finishing rolling inlet temperature: 910±20℃; spinning temperature: 930℃±10℃; insulation hood: all open, the fan opening degree 1-5# fans are open at 90%, and 6-10 fans are open at 50%.

[0012] Further, 200 kg of lime was added.

[0013] Furthermore, the number of pieces discharged from the furnace is controlled at 40 pieces per hour.

[0014] Furthermore, the roller speed is shown in the following table:

[0015]

[0016] Furthermore, the final wire rod structure is controlled to be troostite by this method, and the troostitization rate is above 80%.

[0017] Compared with the prior art, the beneficial technical effects of the present invention are:

[0018] By implementing the method, the drawing performance of high carbon steel is improved and it can be drawn smoothly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings.

[0020] Figure 1 Schematic diagram of the final wire rod organization. DETAILED DESCRIPTION

[0021] In order to solve the problem that Baosteel's high carbon steel cannot be drawn, the cleanliness of the steel is improved through smelting, the structure of the high carbon steel is regulated, and the smooth drawing of the high carbon steel is achieved. The patent of this invention provides a method for smelting and producing high carbon drawing materials and regulating the structure of wire rods. Through the implementation of this method, the drawing performance of high carbon steel is improved, and it can be drawn smoothly. The composition requirements of the high carbon drawing materials involved are C: 0.69-0.71%, Si: 0.20-0.30%, Mn: 0.60-0.70%, P: ≤0.020%, S≤0.015%, N≤0.0040%, O: 0.0020%. The specific content of the invention is as follows:

[0022] The conditions of molten iron entering the furnace are Si: 0.30-0.50%, S≤0.015%, P≤0.120%, Ti≤0.10%, T≥1250℃. The amount of slag should not exceed 0.5%. At the same time, the residual elements are required to be controlled as follows: Cr≤0.20%, Ni≤0.20%, Cu≤0.20%.

[0023] The converter adopts high carbon drawing process, the final composition of the steel is C ≥ 0.06%, P ≤ 0.020%, S ≤ 0.015%, C greater than 0.10% accounts for 80%, T: 1610 ~ 1630 ℃. The order of alloying addition of converter steel is low nitrogen carburizer + ferrosilicon + silicon manganese (ferromanganese) converter top slag addition: add 200 kg of lime after the alloy is added. The required in-station composition is shown in the following table.

[0024] Table 1 Composition of high carbon drawn materials entering the refining station

[0025] Steel Type C Si Mn P S High carbon drawn material 0.60～0.65 0.15～0.20 0.55～0.60 ≤0.020 ≤0.015

[0026] LF refining operation requires opening the working door, adjusting the argon flow rate, and controlling the diameter of the blow-open area to about 300-400mm. After heating for 5 minutes, it is necessary to perform oxygen determination operation, and add 300kg of quartz sand and 50kg of small ash during the heating process. 50kg of calcium carbide and 50kg of ferrosilicon powder are added intermittently during the heating process. After heating for 5 minutes, dip the slag to observe the white slag situation, and measure the temperature and take samples at the same time. According to the oxygen determination and slag situation, add 50kg of ferrosilicon powder. The deoxidizer is required to be sprinkled on the slag surface. After the next heating stops, dip the sample to observe the color of the slag. If it is transparent glass slag, it is considered that the white slag is made, otherwise continue to sprinkle the deoxidizer. The amount of alloy added is adjusted according to the requirements of internal control components. The heating time of the entire refining process is not less than 15 minutes, and the temperature measurement operation is performed before the end of the treatment. The atmosphere in the bag is guaranteed to be a reducing atmosphere during the entire refining process, and there is a slight smoke during the heating process. If the sampled sulfur is high, the amount of lime can be increased during the heating process, and the desulfurization rate is considered to be 0.002-0.003% per 100kg of lime. After treatment, secondary heating due to other reasons must be repeated for slag making. If the steel ladle was used to produce aluminum-killed steel last time, calcium wire is fed for calcium treatment. The wire feeding amount is controlled at 50-100m according to the heating time. The soft blowing time is more than 15min, and the molten steel must not be exposed during the soft blowing process. The requirements for the use of covering agent are R<2.0, FeO<1.0%.

[0027] The chemical composition shall comply with the above provisions, and require narrow composition control, with the C content fluctuating within the range of 0.69%-0.71%.

[0028] The continuous casting machine operation requires vibration: 190 times / min, amplitude 4mm; covering agent: use carbonized rice husk or low alkalinity covering agent; specific water content is 0.8L / kg. The terminal electric stirring parameters implement the following experimental scheme: current 300A, frequency 8Hz experiment 1-2 heats; current 330A, frequency 8Hz experiment 1-2 heats. Before continuous casting production, the crystallizer, foot roller and fan-shaped segment roller must be aligned and confirmed; the protective casing gas volume must be >4m 3 / h; the atmosphere replacement pipeline and atmosphere replacement time must be confirmed on site.

[0029] The temperature of the first furnace is 35-55℃, and the pulling speed is controlled at 1.7-2.1m / min. The other furnaces are cast at a constant pulling speed, with a control target of 1.9m / min. The temperature control target of the tundish after the second furnace is 1497-1507℃, and the superheat of the furnace needs to be controlled at 20-30℃. When the temperature of the tundish is greater than 1512℃, the pulling speed is reduced to 1.8m / min, and when the temperature of the tundish is less than 1497℃, the pulling speed is 2m / min, and other temperatures are 1.9m / min. The liquid level fluctuation is not allowed to exceed ±5mm, and the liquid level height of the tundish is ≥600mm. When burning the residue in the casing of the large ladle, the lower end of the casing of the large ladle must be placed outside the tundish. It is not allowed to burn oxygen drainage and bare pouring, and the judgment will be changed if it exceeds the standard.

[0030] Non-metallic inclusions are inspected in each furnace, and the inclusion level is implemented according to the requirements of Table 2. If the inclusion level exceeds the standard, the judgment will be revised.

[0031] Table 2 Non-metallic inclusions / grade

[0032] Category A Category B Category C Category D Ds Class ≤2.0 ≤1.5 ≤1.5 ≤1.5 ≤1.0

[0033] The ingot shall not have serious de-squareness, bulging, or central shrinkage. Low-magnification hot acid test specimens of the ingot shall be taken from each furnace for inspection. The defect levels of subcutaneous cracks, subcutaneous bubbles, corner cracks, and middle cracks shall not be greater than level 1.5, and the remaining defects shall not be greater than level 2. Ingots exceeding the standards shall be re-judged.

[0034] The material loader shall carefully check the shape and surface quality of the billet, reject the unqualified billet, and mark it in time. It is strictly forbidden to put unqualified billet into the furnace. Turn on the high-pressure water descaling during rolling to ensure the working pressure of the descaling water and the smooth flow of the nozzle. The pressure is ≥10MPa to ensure that all the iron oxide scale on the surface of the billet is removed. Harmful defects such as cracks, folds, inclusions, ears, scars, and delamination are not allowed on the surface of the wire rod. Defects such as pits, pits, scratches, etc. with a depth (or height) greater than 0.10mm are not allowed on the surface of the wire rod.

[0035] The temperature of the heating section is 1100±20℃, the temperature of the soaking section is 1110±20℃, the tail of the billet is 20℃ higher than the head, the heating time is controlled at 120±15min, and the residual oxygen is 1-4%. The number of billets out of the furnace is controlled at 40 / hour, and the outlet temperature of 1# is 1020±20℃. The entrance temperature of the finishing rolling is 910±20℃. The wire laying temperature is 930℃±10℃. The heat preservation cover: all open, the roller speed (see the table below), the fan opening degree 1-5# fans open 90%, 6-10 fans open 50%. The finished product precision is controlled according to Class C.

[0036] Table 3 Roller speed control requirements

[0037]

[0038] In order to better illustrate the invention content of the patent of this invention, specific operation methods are proposed, and specific examples are analyzed. The specific implementation methods are as follows.

[0039] Through the above-mentioned desulfurization-converter-refining-continuous casting-rolling key process control, high carbon steel has good drawing performance. The conditions of molten iron entering the furnace are Si: 0.30-0.50%, S≤0.015%, P≤0.120%, Ti≤0.10%, T≥1250℃. The amount of slag shall not exceed 0.5%. At the same time, the residual elements are required to be controlled: Cr≤0.20%, Ni≤0.20%, Cu≤0.20%. The converter adopts a high carbon drawing process, and the final composition of the steel is C≥0.06%, P≤0.020%, S≤0.015%, C greater than 0.10% accounts for 80%, T: 1610-1630℃. The entire refining strictly implements the white slag operation according to the above operation, and the amount of alloy added is adjusted according to the internal control component requirements. The heating time of the entire refining process is not less than 15 minutes, and the temperature measurement operation is carried out before the end of the treatment. The entire refining process ensures that the atmosphere in the bag is a reducing atmosphere, and there is a slight smoke during the heating process. The soft blowing time is more than 15 minutes, and the molten steel shall not be exposed during the soft blowing process. Except for the first furnace, the other furnaces are cast at a constant speed, with a control target of 1.9m / min, and the furnace superheat needs to be controlled at 20-30℃. Adjust the casting speed according to the superheat situation, and the liquid level fluctuation is not allowed to exceed ±5mm, and the tundish liquid level height is ≥600mm.

[0040] During rolling, the size and surface quality of the billet shall be carefully checked. Unqualified billets shall be discarded and marked in time. Unqualified billets are strictly prohibited from entering the furnace. High-pressure water descaling is turned on during rolling to ensure the working pressure of the descaling water and the smooth flow of the nozzle. The pressure is ≥10MPa to ensure that all the iron oxide scale on the surface of the billet is removed. Harmful defects such as cracks, folds, inclusions, ears, scars, and delamination are not allowed on the surface of the wire rod. Defects such as pits, pits, and scratches with a depth (or height) greater than 0.10mm are not allowed on the surface of the wire rod.

[0041] The temperature of the heating section is 1100±20℃, the temperature of the equalizing section is 1110±20℃, the tail of the billet is 20℃ higher than the head, the heating time is controlled at 120±15min, and the residual oxygen is 1-4%. The number of rods out of the furnace is controlled at 40 rods / hour, and the outlet temperature of 1# is 1020±20℃. The entrance temperature of finishing rolling is 910±20℃. Wire drawing temperature: 930℃±10℃. Insulation hood: all open, roller speed (see the table below), fan opening degree 1-5# fans open 90%, 6-10 fans open 50%. The starting roller speed is 0.70m / s. Through this operation, the final wire rod structure is controlled to be troostite, and the troostitization rate is above 80%. Figure 1 shown.

[0042] Table 4 Sorbentization rate and non-metallic inclusions

[0043]

[0044]

[0045] The patent of the present invention is reliable to implement, and users can pull and use it smoothly. The method quantifies the key technical requirements, so it is easy to promote and implement in all converter-refining-continuous casting-rolling processes, and the implementation effect can be guaranteed.

[0046] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for smelting and producing high-carbon drawn materials and controlling the structure of wire rods, characterized in that: include: Hot metal conditions for furnace entry: Si: 0.30-0.50%, S≤0.015%, P≤0.120%, Ti≤0.10%, T≥1250℃. The amount of slag should not exceed 0.5%. At the same time, residual elements are required to be controlled: Cr≤0.20%, Ni≤0.20%, Cu≤0.20%; The converter adopts high carbon drawing process, the final composition of the steel is C ≥ 0.06%, P ≤ 0.020%, S ≤ 0.015%, C greater than 0.10% accounts for 80%, T: 1610 ~ 1630 ℃; the alloying sequence of converter steel is low nitrogen carburizer + ferrosilicon + silicon manganese or ferromanganese, converter top slag is added, and lime is added after the alloy is added; LF refining operation requires opening the working door, adjusting the argon flow rate, and controlling the diameter of the blown area to about 300-400mm; after heating for 5 minutes, it is necessary to perform oxygen determination operation, and add 300kg of quartz sand and 50kg of small ash during the heating process; add 50kg of calcium carbide and 50kg of ferrosilicon powder intermittently during the heating process. After heating for 5 minutes, dip the slag to observe the white slag situation, and measure the temperature and take samples at the same time. According to the oxygen determination and slag situation, add 50kg of ferrosilicon powder. The deoxidizer is required to be sprinkled on the slag surface. After the next heating stops, dip the sample to observe the slag color. If it is transparent glass slag, it is considered that the white slag is made, otherwise continue to sprinkle the deoxidizer; the amount of alloy added is based on The internal control component requirements are adjusted; the heating time of the entire refining process is not less than 15 minutes, and the temperature measurement operation is carried out before the end of the treatment; the atmosphere in the ladle is guaranteed to be a reducing atmosphere during the entire refining process, and there is slight smoke during the heating process; if the sample sulfur is high, the amount of lime is increased during the heating process, and 0.002-0.003% desulfurization is considered for every 100kg of lime; after treatment, secondary heating due to other reasons must be re-slag making. If the ladle was used to produce aluminum-killed steel last time, calcium wire is fed for calcium treatment, and the wire feeding amount is controlled at 50-100m according to the length of heating time; the soft blowing time is more than 15min, and the molten steel must not be exposed during the soft blowing process. Covering agent use requirements R <2.0, FeO <1.0%; In addition to the chemical composition meeting the above requirements, narrow component control is required, and the C content fluctuation range is 0.69%-0.71%; the continuous casting machine operation requires vibration: 190 times / min, amplitude 4mm; covering agent: use carbonized rice husk or low alkalinity covering agent; specific water volume is 0.8L / kg; the terminal electric stirring parameters implement the following experimental scheme; current 300A, frequency 8Hz experiment 1-2 heats; current 330A, frequency 8Hz experiment 1-2 heats; before continuous casting production, the crystallizer, foot roller and fan-shaped segment roller must be aligned and confirmed; the protective casing gas volume must be >4m 3 / h; atmosphere replacement pipeline and atmosphere replacement time must be confirmed on site; The temperature of the first furnace is 35-55℃, and the pulling speed is controlled at 1.7-2.1m / min. The other furnaces are cast at a constant pulling speed, and the control target is 1.9m / min. The temperature control target of the tundish after the second furnace is 1497-1507℃, and the superheat of the furnace needs to be controlled at 20-30℃. When the tundish temperature is greater than 1512℃, the pulling speed is reduced to 1.8m / min. When the tundish temperature is less than 1497℃, the pulling speed is 2m / min, and other temperatures are 1.9m / min. The liquid level fluctuation is not allowed to exceed ±5mm, and the tundish liquid level height is ≥600mm; The temperature of the heating section is 1100±20℃, the temperature of the soaking section is 1110±20℃, the tail of the billet is 20℃ higher than the head, the heating time is controlled at 120±15min, the residual oxygen is 1-4%; the number of billets out of the furnace is controlled at 35-45 / hour, the outlet temperature of 1# is 1020±20℃; the entrance temperature of the finishing rolling is 910±20℃; the wire laying temperature is 930℃±10℃; Insulation cover: All open, fan opening degree 1-5 fans open 90%, 6-10 fans open 50%.

2. The method for smelting and producing high-carbon drawn materials and controlling the structure of wire rods according to claim 1, characterized in that: Add 200Kg of lime.

3. The method for smelting and producing high-carbon drawn materials and controlling the structure of wire rods according to claim 1, characterized in that: The number of pieces out of the oven is controlled at 40 pieces per hour.

4. The method for smelting and producing high-carbon drawn materials and controlling the structure of wire rods according to claim 1, characterized in that: The roller speeds are shown in the following table:

5. The method for smelting and producing high-carbon drawn materials and controlling the structure of wire rods according to claim 1, characterized in that: By this method, the final wire rod structure is controlled to be troostite, and the troostitization rate is above 80%.

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