Plasticizing control method for 45 # steel inclusions

Abstract

The invention belongs to the technical field of steel production, and relates to a plasticization control method for 45 # steel inclusions, the smelting process adopts converter smelting, argon station, LF refining, RH refining and continuous casting, according to the characteristics of the inclusions in the 45 # steel smelting process and the use performance requirement of a wire rod, a smelting process is precisely regulated and controlled, and the plasticization control method for the 45 # steel inclusions with the components of 45%-50% of CaO, smaller than or equal to 10.2% of Al2O3, 32.8%-40.4% of SiO2, 4%-6% of MgO and the balance of Fe and inevitable impurities is obtained. According to the method, the content of [Al] s in the steel is controlled to be 6-10 ppm, the content of [Ca] in the steel is controlled to be 5-8 ppm, plastifying transformation of non-deformation inclusions is effectively promoted, the risk of wire rod drawing fracture caused by the inclusions is remarkably reduced, and then the overall quality and production efficiency of the steel are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of steel production and relates to a method for controlling plasticization of 45# steel inclusions. Background Art

[0002] 45# steel hard wire rod has high strength and excellent machinability, and is often used as the main raw material for making steel wire ropes and steel strands. However, 45# steel wire rods often break during the drawing process. Studies have found that large-sized inclusions with poor deformation ability in steel are one of the main reasons for inducing wire rod drawing fracture. Therefore, strict requirements are placed on the cleanliness of steel and inclusion control. The production of 45# steel mainly adopts the silicon-manganese deoxidation process. The main non-deformable inclusions in the molten steel are CaO-SiO2-Al2O3-MgO. Although it is almost impossible to completely remove the inclusions in actual production, the residual inclusions can be plasticized, deformed or broken during hot rolling or drawing, and the size of the inclusions can be reduced to achieve harmlessness of the inclusions.

[0003] Chinese patent CN115595402A discloses a 45# steel refining and slag making method. According to the characteristics of MnO-Al2O3-SiO2 and CaO-Al2O3-SiO2 inclusions in 45# steel, a specific slag system and deoxidation process are adopted to ensure that the inclusions in the steel are in a low melting point area and have good deformation ability and plasticity. This method is mainly used to control ternary inclusions in steel, and the influence and regulation mechanism of quaternary inclusions have not been deeply analyzed. Chinese patent CN116287557A discloses a method for producing silicon-deoxidized 45 steel bars. Through a specific refining process and deoxidation means, the purpose of producing 45# steel bars without using aluminum deoxidizer is achieved, and the problem of Al2O3 inclusions blocking the water inlet and causing stress concentration leading to steel fracture is solved. This method mainly focuses on reducing the generation of Al2O3 inclusions, but the specific properties and effects of the silicate inclusions formed are not elaborated in detail. Not all silicate inclusions have the characteristics of plastic inclusions. Summary of the invention

[0004] In view of this, the purpose of the present invention is to solve the above-mentioned problem and provide a method for controlling the plasticization of inclusions in 45# steel. The method is aimed at typical non-deformed CaO-SiO2-Al2O3-MgO inclusions generated during the refining process of 45# steel. The method effectively promotes the plasticization transformation of CaO-SiO2-Al2O3-MgO inclusions by precisely controlling the smelting process, significantly reduces the risk of wire rod drawing fracture caused by such inclusions, and thereby improves the overall quality and production efficiency of steel.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for controlling plasticization of 45# steel inclusions comprises the following steps:

[0007] Step 1: smelting in a converter, tapping after smelting, adding silicon manganese and ferrosilicon alloy for composite deoxidation during tapping, and adding lime and pre-melted synthetic slag for slagging after tapping;

[0008] Step 2: Enter the argon station and stir vigorously in the argon station;

[0009] Step 3: LF refining, lime is added in 2-3 batches in the early stage of refining, the timing of adding lime is determined according to the actual condition of the slag, and the temperature is raised by power; ferrosilicon, ferromanganese and carburizer are added in the middle stage of refining, the content of C, Si and Mn elements in the molten steel is adjusted to the target composition, and the argon flow rate is adjusted; fluorite balls are added according to the slag condition in the late stage of refining, and the argon flow rate is reduced for soft blowing;

[0010] Step 4: RH refining. After the molten steel temperature reaches the standard and arrives at the RH treatment station, adjust the argon flow rate to start vacuuming and perform vacuum refining. After re-pressing, add SiC for soft blowing.

[0011] Step 5: Continuous casting: the molten steel is transported to the continuous casting platform for casting.

[0012] Furthermore, in step one, the tapping temperature of the converter is controlled to be ≥1590°C, and feeding begins when 30-40% of the tapping is completed, with 5.5-6.0 kg / t of manganese silicon alloy, 1.0-2.0 kg / t of ferrosilicon, and 3.3-4.0 kg / t of recarburizer. After the tapping is completed, 2.5-3.5 kg / t of lime and 4.0-5.0 kg / t of pre-melted synthetic slag are added.

[0013] Furthermore, in step three, the amount of lime added in each batch is 1.0-2.0 kg / t, and the temperature is raised to above 1570°C.

[0014] Furthermore, in step 3, 0.7-1.5 kg / t of ferrosilicon, 1.7-2.5 kg / t of high carbon ferromanganese, 0.3-0.7 kg / t of carburizer are added in the middle of refining, and the argon flow rate is set to 50-70 Nm 3 / h.

[0015] Furthermore, in step 3, fluorite balls are added at a rate of 0.2-0.5 kg / t in the later stage of refining, the temperature is maintained above 1600°C, and the argon flow rate is reduced to 20-40 Nm 3 / h, soft blowing for about 10 to 15 minutes.

[0016] Furthermore, in step 4, RH enters the station, the molten steel temperature is controlled to be ≥1610℃, the RH vacuum is 20Pa, and the argon flow rate is 70~80Nm 3 / h, the amount of SiC added is 20-30kg, and the soft blowing time is 20-25 minutes.

[0017] Furthermore, the slag components obtained in the refining process are CaO: 45% to 50%, Al2O3: ≤10.2%, SiO2: 32.8% to 40.4%, MgO: 4% to 6%, and the slag basicity is 1.0 to 1.5.

[0018] Furthermore, the composition of the molten steel obtained after controlled refining is, by mass percentage, C: 0.44%~0.47%, Si: 0.18%~0.28%, Mn: 0.60%~0.70%, P: ≤0.020%, S: ≤0.01%, Al: 0.002%~0.004%, and the balance is iron.

[0019] Furthermore, the [Al]s content in the produced steel is 6-10ppm, and the [Ca] content is 5-8ppm; the inclusions in the ingot are mainly low-melting point CaO-SiO2-Al2O3-MgO system, the inclusion morphology is mainly spherical, and the inclusion size is between 1 and 5um.

[0020] The beneficial effects of the present invention are:

[0021] The smelting process of the present invention adopts converter smelting→argon station→LF refining→RH refining→continuous casting. According to the characteristics of inclusions in the smelting process of 45# steel and the performance requirements of wire rods, the smelting process is precisely controlled to obtain slag with the composition of CaO: 45%-50%, Al2O3: ≤10.2%, SiO2: 32.8%-40.4%, MgO: 4%-6%, and basicity of 1.0-1.5, and the [Al]s content in the steel is controlled to be 6-10ppm, and the [Ca] content is controlled to be 5-8ppm, so that the plastic transformation of non-deformed inclusions is effectively promoted, and the risk of wire rod drawing fracture caused by such inclusions is significantly reduced, thereby improving the overall quality and production efficiency of the steel.

[0022] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. DETAILED DESCRIPTION

[0023] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0024] Example 1

[0025] Step 1: smelting in converter, tapping after smelting, adding materials when tapping is 35%, 5.5kg / t of manganese silicon alloy, 1.5kg / t of ferrosilicon, 3.5kg / t of carburizer, 2.6kg / t of lime and 4.0kg / t of pre-melted synthetic slag are added after tapping;

[0026] Step 2: Enter the argon station and stir vigorously in the argon station;

[0027] Step 3: LF refining. Lime is added in two batches in the early stage of refining. The timing of adding lime is determined according to the actual slag conditions. The amount of lime added in each batch is 2.0 kg / t. The temperature is raised to 1590 °C. Ferrosilicon, ferromanganese, carburizer, etc. are added in the middle stage of refining to adjust the content of C, Si, and Mn elements in the molten steel to the target composition. The argon flow rate is set to 60 Nm 3 / h; in the later stage of refining, fluorite balls are added according to the slag conditions, the temperature is maintained at 1610℃, and the argon flow rate is reduced to 25Nm 3 / h, soft blowing for about 15 minutes;

[0028] Step 4: RH refining, the molten steel inlet temperature is 1615℃, the RH vacuum is 20Pa, and the argon flow rate is 75Nm 3 / h, SiC addition amount is 20kg, and soft blowing time is 20 minutes;

[0029] Step 5: Continuous casting: the molten steel is transported to the continuous casting platform for casting.

[0030] After implementing the above steps, the slag components obtained in the refining process are CaO: 46%, Al2O3: 9.2%, SiO2: 34.5%, MgO: 5%, and the basicity is 1.33. The [Al]s content in the steel is 9ppm, the [Ca] content is 8ppm, and the CaO-SiO2-Al2O3-MgO inclusion composition is in the low melting point phase region, with good plasticity.

[0031] Example 2

[0032] Step 1: smelting in converter, tapping after smelting, start adding materials when tapping is 35%, 5.8kg / t of manganese silicon alloy, 2.0kg / t of ferrosilicon, 3.7kg / t of carburizer, 3.3kg / t of lime and 4.5kg / t of pre-melted synthetic slag are added after tapping.

[0033] Step 2: Enter the argon station and stir vigorously in the argon station;

[0034] Step 3: LF refining. In the early stage of refining, lime is added in two batches. The timing of adding lime is determined according to the actual slag conditions. The amount of lime added in each batch is 2.0 kg / t. The temperature is raised to 1580 °C. In the middle stage of refining, ferrosilicon, ferromanganese, carburizer, etc. are added to adjust the C, Si, and Mn element contents in the molten steel to the target composition. The argon flow rate is set to 65 Nm 3 / h; in the later stage of refining, fluorite balls are added according to the slag conditions, the temperature is maintained at 1610℃, and the argon flow rate is reduced to 26Nm 3 / h, soft blowing for about 15 minutes;

[0035] Step 4: RH refining, the molten steel inlet temperature is 1612℃, the RH vacuum is 20Pa, and the argon flow rate is 77Nm 3 / h, SiC addition amount is 20kg, and soft blowing time is 20 minutes;

[0036] Step 5: Continuous casting: the molten steel is transported to the continuous casting platform for casting.

[0037] After implementing the above steps, the slag components obtained in the refining process are CaO: 50%, Al2O3: 9.0%, SiO2: 36%, MgO: 5%, and the basicity is 1.38. The [Al]s content in the steel is 8ppm, the [Ca] content is 8ppm, the CaO-SiO2-Al2O3-MgO inclusion composition is in the low melting point phase region, and has good plasticity.

[0038] Example 3

[0039] Step 1: smelting in converter, tapping after smelting, start adding materials when 30% of the steel is tapped, 6.0kg / t of manganese silicon alloy, 1.8kg / t of ferrosilicon, 3.6kg / t of carburizer, 3.5kg / t of lime and 4.6kg / t of pre-melted synthetic slag are added after tapping.

[0040] Step 2: Enter the argon station and stir vigorously in the argon station;

[0041] Step 3: LF refining. Lime is added in two batches in the early stage of refining. The timing of adding lime is determined according to the actual slag conditions. The amount of lime added in each batch is 1.8 kg / t. The temperature is raised to 1600 °C. Ferrosilicon, ferromanganese, carburizer, etc. are added in the middle stage of refining to adjust the content of C, Si, and Mn elements in the molten steel to the target composition. The argon flow rate is set to 68 Nm 3 / h; in the later stage of refining, fluorite balls are added according to the slag conditions, the temperature is maintained at 1612℃, and the argon flow rate is reduced to 30Nm 3 / h, soft blowing for about 15 minutes;

[0042] Step 4: RH refining, the molten steel inlet temperature is 1615℃, the RH vacuum is 20Pa, and the argon flow rate is 75Nm 3 / h, SiC addition amount is 20kg, and soft blowing time is 20 minutes;

[0043] Step 5: Continuous casting: the molten steel is transported to the continuous casting platform for casting.

[0044] After implementing the above steps, the slag components obtained in the refining process are CaO: 48%, Al2O3: 8.5%, SiO2: 35%, MgO: 5%, and the basicity is 1.37. The [Al]s content in the steel is 9ppm, the [Ca] content is 8ppm, and the CaO-SiO2-Al2O3-MgO inclusion composition is in the low melting point phase region, with good plasticity.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for controlling plasticization of 45# steel inclusions, characterized in that: The following steps are involved: Step 1: Converter smelting, tapping after smelting, adding silicon manganese and ferrosilicon alloy for composite deoxidation during tapping, adding lime and pre-melted synthetic slag for slagging after tapping; Step 2: Enter the argon station and stir vigorously in the argon station; Step 3: LF refining, lime is added in 2-3 batches in the early stage of refining, the timing of adding lime is determined according to the actual condition of the slag, and the temperature is raised by power; ferrosilicon, ferromanganese and carburizer are added in the middle stage of refining, the content of C, Si and Mn elements in the molten steel is adjusted to the target composition, and the argon flow rate is adjusted; fluorite balls are added according to the slag condition in the late stage of refining, and the argon flow rate is reduced for soft blowing; Step 4: RH refining. After the molten steel temperature reaches the standard and arrives at the RH treatment station, adjust the argon flow rate to start vacuuming and perform vacuum refining. After re-pressing, add SiC for soft blowing. Step 5: Continuous casting: the molten steel is transported to the continuous casting platform for casting.

2. The 45# steel inclusion plasticization control method according to claim 1 is characterized in that: In step 1, the tapping temperature of the converter is controlled to be ≥1590°C, and the material is added when 30-40% of the steel is tapped, including 5.5-6.0 kg / t of manganese silicon alloy, 1.0-2.0 kg / t of ferrosilicon, and 3.3-4.0 kg / t of carburizer. After the tapping is completed, 2.5-3.5 kg / t of lime and 4.0-5.0 kg / t of pre-melted synthetic slag are added.

3. The 45# steel inclusion plasticization control method according to claim 1, characterized in that: In step 3, the amount of lime added in each batch is 1.0-2.0 kg / t, and the temperature is raised to above 1570°C.

4. The 45# steel inclusion plasticization control method according to claim 1, characterized in that: In step 3, add 0.7-1.5kg / t of ferrosilicon, 1.7-2.5kg / t of high carbon ferromanganese, 0.3-0.7kg / t of carburizer in the middle of refining, and set the argon flow rate to 50-70Nm 3 / h.

5. The 45# steel inclusion plasticization control method according to claim 1, characterized in that: In step 3, fluorite balls are added at a rate of 0.2-0.5 kg / t in the later stage of refining, the temperature is maintained above 1600°C, and the argon flow rate is reduced to 20-40 Nm 3 / h, soft blowing for about 10 to 15 minutes.

6. The 45# steel inclusion plasticization control method according to claim 1, characterized in that: In step 4, RH enters the station, the molten steel temperature should be ≥1610℃, the RH vacuum degree should be 20Pa, and the argon flow rate should be 70~80Nm 3 / h, the amount of SiC added is 20-30kg, and the soft blowing time is 20-25 minutes.

7. The 45# steel inclusion plasticization control method according to claim 1, characterized in that: The components of the slag obtained in the refining process are CaO: 45% to 50%, Al2O3: ≤10.2%, SiO2: 32.8% to 40.4%, MgO: 4% to 6%, and the slag basicity is 1.0 to 1.

5.

8. The 45# steel inclusion plasticization control method according to claim 1, characterized in that: The composition of the molten steel obtained after controlled refining is, by mass percentage, C: 0.44%~0.47%, Si: 0.18%~0.28%, Mn: 0.60%~0.70%, P: ≤0.020%, S: ≤0.01%, Al: 0.002%~0.004%, and the balance is iron.

9. The 45# steel inclusion plasticization control method according to claim 1, characterized in that: The [Al]s content in the produced steel is 6-10ppm, and the [Ca] content is 5-8ppm; the inclusions in the ingot are mainly low-melting point CaO-SiO2-Al2O3-MgO system, the inclusion morphology is mainly spherical, and the inclusion size is between 1 and 5um.