Method for producing high-quality carbon structural steel by using Si sedation

Abstract

The invention relates to a method for producing high-quality carbon structural steel through Si sedation, and belongs to the technical field of steel manufacturing. The method comprises the steps that KR method desulfurization, BOF oxygen blowing, RH refining and continuous casting are sequentially conducted on molten iron, and a plate blank with set chemical components is obtained; wherein the RH refining comprises RH primary refining and RH secondary refining, and low-carbon ferrosilicon is used as a deoxidizing agent in the RH primary refining; the plate blank is sequentially heated and roughly rolled, and an intermediate blank is obtained; and the intermediate billet is subjected to finish rolling, cooling and coiling in sequence, and the high-quality carbon structural steel is obtained. By optimizing smelting and refining processes, low-carbon ferrosilicon is used as a main deoxidizing agent to replace part of aluminum for deoxidation, and the addition amount of aluminum is reduced, so that generation of hard inclusions such as Al2O3 is effectively reduced, the purity and the structure uniformity of steel are improved, and reliable material guarantee is provided for producing the clutch transmission disc with high performance and high quality.

Description

Technical Field

[0001] The present application relates to the technical field of steel manufacturing, and in particular to a method for producing high-quality carbon structural steel using Si killing. Background Art

[0002] In the field of automobile manufacturing, the clutch is an important part of the transmission system, and its performance is directly related to the vehicle's power transmission efficiency, handling stability, and the driver's driving experience. The transmission disc in the clutch, as the core component of this system, carries the key functions of transmitting torque and realizing the connection and separation between the engine and the transmission. Therefore, the material selection and production process of the transmission disc are crucial to ensure the overall performance of the clutch. Traditionally, the transmission disc of automobile clutches is mostly made of high-quality carbon structural steel, which has good strength and toughness and can meet the use requirements of the clutch under complex working conditions. However, for high-performance vehicles or special-purpose clutches, the performance requirements for the transmission disc are more stringent. On the one hand, the transmission disc needs to have excellent wear resistance to cope with frequent friction and wear and extend its service life; on the other hand, its fatigue performance must also meet extremely high standards to ensure that it does not break or fail under long-term and high-load operation.

[0003] In addition, the control of inclusions in the material of the transmission disc is also extremely critical. Inclusions, especially hard inclusions such as Al2O3 formed during the Al killing process, will seriously affect the mechanical properties and processing properties of the steel, and reduce the reliability and service life of the transmission disc. These inclusions act as stress concentration points in the steel, which can easily cause the generation and expansion of cracks, thereby leading to early failure of the transmission disc. Summary of the invention

[0004] The present application provides a method for producing high-quality carbon structural steel using Si killing to solve the following technical problem: how to reduce the inclusion content in high-quality carbon structural steel.

[0005] The present application embodiment provides a method for producing high-quality carbon structural steel using Si killing, the method comprising:

[0006] The molten iron is sequentially subjected to KR desulfurization, BOF oxygen blowing, RH refining and continuous casting to obtain a slab with a set chemical composition; wherein the RH refining includes RH primary refining and RH secondary refining, and the RH primary refining uses low-carbon ferrosilicon as a deoxidizer;

[0007] The slab is sequentially heated and roughly rolled to obtain an intermediate slab;

[0008] The intermediate billet is sequentially subjected to finish rolling, cooling and coiling to obtain high-quality carbon structural steel.

[0009] Optionally, in terms of mass fraction, the set chemical composition includes: C: 0.1% to 0.15%, Si: 0.2% to 0.3%, Mn: 0.3% to 0.5%, P≤0.02%, S≤0.01%.

[0010] Optionally, after the KR process desulfurization, the mass fraction of S is ≤0.001%.

[0011] Optionally, the heated furnace exit temperature is 1200°C to 1250°C.

[0012] Optionally, the thickness of the intermediate blank is 32 mm to 45 mm.

[0013] Optionally, the initial temperature of the finish rolling is 1000°C to 1060°C, and the end temperature of the finish rolling is 860°C to 900°C.

[0014] Optionally, the coiling temperature is 600°C to 660°C.

[0015] Optionally, the microstructure of the high-quality carbon structural steel is mainly ferrite.

[0016] Optionally, the non-metallic inclusions of the high-quality carbon structural steel meet the following requirements: Class B inclusion level ≤ 0.5, Class A inclusion level + Class B inclusion level + Class C inclusion level + Class D inclusion level ≤ 1 level.

[0017] Optionally, the high-quality carbon structural steel meets at least one of the following properties: yield strength ≥290MPa, tensile strength ≥410MPa, elongation after fracture ≥36%, and hardness ≥125HV.

[0018] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0019] The embodiment of the present application provides a method for producing high-quality carbon structural steel using Si sedation, the method comprising: subjecting molten iron to KR desulfurization, BOF oxygen blowing, RH refining and continuous casting in sequence to obtain a slab with a set chemical composition; wherein the RH refining includes RH primary refining and RH secondary refining, and the RH primary refining uses low-carbon ferrosilicon as a deoxidizer; the slab is heated and rough-rolled in sequence to obtain an intermediate slab; the intermediate slab is finely rolled, cooled and coiled in sequence to obtain high-quality carbon structural steel. By optimizing the smelting and refining process, low-carbon ferrosilicon is used as the main deoxidizer to replace part of the aluminum for deoxidation, reducing the amount of aluminum added, thereby effectively reducing the generation of hard inclusions such as Al2O3, improving the purity and uniformity of the steel, and providing a reliable material guarantee for the production of high-performance, high-quality clutch transmission discs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 A schematic flow chart of a method for producing high-quality carbon structural steel using Si killing is provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0024] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range; in addition, whenever a numerical range is indicated in this document, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0025] In this document, the terms including "including" and "including" mean "including but not limited to". Relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "plurality" means two or more; "at least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items; for example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts" such as parts by weight and parts by mass indicate the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, if the weight ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should correspond to the proportional numbers in the proportional formula in the order of description, that is, the weight of substance A: the weight of substance B: the weight of substance C = 1:2:3.

[0026] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0027] Figure 1 A schematic flow chart of a method for producing high-quality carbon structural steel using Si killing provided in an embodiment of the present application;

[0028] like Figure 1 As shown, the embodiment of the present application provides a method for producing high-quality carbon structural steel using Si killing, comprising:

[0029] S1, subjecting molten iron to KR desulfurization, BOF oxygen blowing, RH refining and continuous casting in sequence to obtain a slab with a set chemical composition; wherein the RH refining includes RH primary refining and RH secondary refining, and the RH primary refining uses low-carbon ferrosilicon as a deoxidizer;

[0030] KR desulfurization, full name Kambara Reactor desulfurization, is an effective hot metal pretreatment technology. Its basic principle is to immerse a cross-shaped stirring head that is cast with refractory materials and baked into the molten iron pool to a certain depth. By using the vortex generated by its rotation, the weighed desulfurizer is added to the surface of the hot metal from the feeder and is drawn into the hot metal by the vortex, so that the desulfurizer and the hot metal are fully contacted and reacted to achieve the purpose of desulfurization. KR desulfurization of hot metal can effectively reduce the sulfur content in the hot metal.

[0031] In some embodiments, after the KR process desulfurization, the mass fraction of S is ≤0.001%.

[0032] The mass fraction of S in the molten iron after desulfurization is ≤0.001%, which can ensure the quality of subsequent smelting and steel.

[0033] The basic oxygen furnace (BOF) uses oxygen blowing to make steel. By blowing oxygen-rich air into the molten pool, part of the carbon in the molten pool is burned to release heat, and part of it is dissolved in the high-temperature molten pool to reduce the iron oxides and produce liquid molten steel. The molten steel after smelting is subjected to RH refining. Through RH refining, the composition and temperature of the molten steel can be further adjusted to prepare for subsequent continuous casting. RH refining includes RH primary refining, LF furnace heating and RH secondary refining. The main purpose of RH primary refining is to remove gas and inclusions in the molten steel and adjust the composition of the molten steel. During the RH refining process, the molten steel circulates in a vacuum chamber, and by blowing inert gases such as argon, the gas and inclusions in the molten steel are extracted, thereby achieving the purpose of refining. The LF (Ladle Furnace) furnace, that is, the ladle refining furnace, is a device used to heat and refine molten steel. The main purpose of LF furnace heating is to heat the molten steel to the required temperature to ensure the smooth progress of subsequent processes. During the heating process, the LF furnace can also further refine the molten steel to remove harmful gases and inclusions in the molten steel. RH secondary refining is to further refine the molten steel on the basis of primary refining. The main purpose of RH secondary refining is to further remove gases and inclusions in the molten steel, and at the same time adjust the composition and temperature of the molten steel to ensure the quality and performance of the final molten steel.

[0034] In the RH primary refining process, in addition to aluminum, low carbon ferrosilicon is used as a deoxidizer to remove dissolved oxygen in the molten steel.

[0035] Aluminum is a traditional deoxidizer. Although it has a good deoxidation effect, it is easy to generate hard inclusions such as Al2O3, which affect the performance of steel. Low-carbon ferrosilicon has a lower carbon content and a higher silicon content, which makes it an ideal deoxidizer. The silicon element reacts with oxygen in molten steel to generate silicon oxides (SiO2), which are relatively easy to remove from the molten steel, thereby reducing the generation of inclusions. Compared with aluminum, silicon oxide (SiO2) has lower hardness and brittleness, and has less effect on the mechanical properties and processing properties of steel. The embodiment of the present application uses low-carbon ferrosilicon as the main deoxidizer, replacing part of the aluminum for deoxidation, reducing the amount of aluminum added, thereby effectively reducing the generation of hard inclusions such as Al2O3.

[0036] The molten steel after RH refining is continuously cast to obtain slabs with set chemical composition. Continuous casting is an advanced technology that directly pours and solidifies liquid steel. It eliminates the demoulding, mold filling, ingot soaking and billet opening processes in the traditional die casting process, making the production process more simplified. During the continuous casting process, the molten steel is distributed to each crystallizer through the tundish, and then cooled and solidified into a cast billet in the crystallizer. Finally, after cutting, conveying and other steps, the billet of the required specifications is obtained.

[0037] In some embodiments, the set chemical composition includes, by mass fraction: C: 0.1% to 0.15%, Si: 0.2% to 0.3%, Mn: 0.3% to 0.5%, P≤0.02%, S≤0.01%.

[0038] The positive effect of limiting the mass fraction of C to 0.1% to 0.15%: C is the main alloying element in steel and has a significant effect on the mechanical properties and processing properties of steel. The mass fraction of C is 0.1% to 0.15%, which can not only ensure that the steel has a certain strength and hardness, but also avoid the brittleness and difficulty in processing caused by too high a mass fraction of C. Exemplarily, the mass fraction of C can be 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, etc.

[0039] The positive effect of limiting the mass fraction of Si to 0.2% to 0.3% is that Si, as a deoxidizer, can reduce the oxygen content in steel, thereby reducing the formation of inclusions. At the same time, Si can also improve the strength and hardness of steel and help improve its corrosion resistance. The mass fraction of Si is 0.2% to 0.3%, which can not only meet the deoxidation requirements, but also will not adversely affect other properties of steel. Exemplarily, the mass fraction of Si can be 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3%, etc.

[0040] The positive effect of limiting the mass fraction of Mn to 0.3% to 0.5% is that Mn is an important alloying element in steel and can improve the strength and hardness of steel. At the same time, Mn can also improve the hardenability and toughness of steel, so that it can obtain a better microstructure during heat treatment. The mass fraction of Mn is 0.3% to 0.5%, which can meet the strength and toughness requirements of steel. Exemplarily, the mass fraction of Mn can be 0.3%, 0.34%, 0.38%, 0.42%, 0.46%, 0.5%, etc.

[0041] The positive effect of limiting the mass fraction of P to ≤ 0.02%: P is one of the harmful elements in steel, which will reduce the toughness and plasticity of steel. By strictly controlling the mass fraction of P, its adverse effects on the properties of steel can be avoided. For example, the mass fraction of P can be 0.01%, 0.012%, 0.014%, 0.016%, 0.018%, 0.02%, etc.

[0042] The positive effect of limiting the mass fraction of S to ≤ 0.01%: S is also a harmful element in steel. It will reduce the strength and toughness of steel and may cause hot brittleness. By strictly controlling the mass fraction of S, it can be ensured that the steel has good mechanical properties and processing properties. For example, the mass fraction of S can be 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, etc.

[0043] S2, heating and rough rolling the slab in sequence to obtain an intermediate slab;

[0044] In some embodiments, the heated furnace temperature is 1200°C to 1250°C.

[0045] The furnace temperature is one of the key factors affecting the microstructure and properties of steel. Limiting the furnace temperature to the range of 1200℃ to 1250℃ can ensure that the steel obtains a uniform temperature distribution during the heating process, thereby avoiding the phenomenon of uneven organization caused by local overheating or overcooling. This temperature range helps the steel obtain a ferrite-based microstructure, which has good toughness and plasticity and can meet the requirements of components such as clutch transmission plates for the mechanical properties of steel. Exemplarily, the heated furnace temperature can be 1200℃, 1210℃, 1220℃, 1230℃, 1240℃, 1250℃, etc.

[0046] In some embodiments, the intermediate blank has a thickness of 32 mm to 45 mm.

[0047] The thickness of the intermediate billet after rough rolling is 32 mm to 45 mm, providing a suitable billet size for subsequent finish rolling. For example, the thickness of the intermediate billet can be 32 mm, 35 mm, 37 mm, 39 mm, 41 mm, 43 mm, 45 mm, etc.

[0048] S2. The intermediate billet is sequentially subjected to finish rolling, cooling and coiling to obtain high-quality carbon structural steel.

[0049] In some embodiments, the initial temperature of the finish rolling is 1000°C to 1060°C, and the end temperature of the finish rolling is 860°C to 900°C.

[0050] Precise control of the finishing temperature range helps to obtain an ideal microstructure. Within the above temperature range, the austenite in the steel can undergo appropriate deformation and transform into the desired ferrite structure during the subsequent cooling process, thereby improving the mechanical properties of the steel. By accurately controlling the initial and final temperatures of finishing rolling, it is possible to ensure that the steel obtains good deformation and recrystallization effects during the rolling process, thereby improving the mechanical properties of the steel such as yield strength, tensile strength, and elongation after fracture. Finishing rolling temperature also has a significant effect on the processing properties of steel. Finishing rolling at the above temperature can ensure that the steel has good plasticity and toughness, thereby facilitating subsequent processing operations such as cutting, bending, and welding. Exemplarily, the initial temperature of finishing rolling can be 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, 1060°C, etc.; the final temperature of the finishing rolling can be 860°C, 870°C, 880°C, 890°C, 900°C, etc.

[0051] In some embodiments, the coiling temperature is 600°C to 660°C.

[0052] At a coiling temperature of 600°C to 660°C, the ferrite in the steel can undergo sufficient phase transformation and strengthening, thereby improving the yield strength, tensile strength and other mechanical properties of the steel. At the same time, a suitable coiling temperature can also maintain the toughness and plasticity of the steel, ensuring that it can maintain good deformation ability when subjected to stress. Exemplarily, the coiling temperature can be 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, etc.

[0053] In some embodiments, the microstructure of the high-quality carbon structural steel is mainly ferrite.

[0054] The microstructure of high-quality carbon structural steel is mainly ferrite, which has good mechanical properties and processing properties.

[0055] In some embodiments, the non-metallic inclusions in the high-quality carbon structural steel meet the following requirements: Class B inclusion level ≤ 0.5, Class A inclusion level + Class B inclusion level + Class C inclusion level + Class D inclusion level ≤ 1 level.

[0056] Class B inclusions are mainly alumina inclusions, most of which are not deformed, angular, have a small shape ratio (generally <3), are black or bluish, and are arranged in a row along the rolling direction. This type of inclusion is likely to become a fatigue source in steel, which has an adverse effect on the fatigue strength and toughness of the steel. Therefore, controlling the level of Class B inclusions below 0.5 can significantly reduce its adverse effect on the properties of steel. In addition to Class B inclusions, Class A, Class C and Class D inclusions also have an important impact on the properties of steel. Class A inclusions are sulfides with high ductility; Class C inclusions are silicates with high ductility and smooth boundaries; Class D inclusions are spherical oxides, which are not deformed and are mostly angular or round in shape. The presence of these inclusions will reduce the purity and uniformity of the steel, thereby affecting its mechanical properties and processing properties. By controlling the sum of the levels of Class A, Class B, Class C and Class D inclusions below Class 1, we can ensure that the total content of inclusions in the steel is low, thereby improving the purity and uniformity of the steel. This helps to improve the mechanical properties and processing properties of the steel and meet the needs of various application scenarios.

[0057] In some embodiments, the high-quality carbon structural steel meets at least one of the following properties: yield strength ≥ 290 MPa, tensile strength ≥ 410 MPa, elongation after fracture ≥ 36%, and hardness ≥ 125 HV.

[0058] Yield strength is the minimum stress value at which steel begins to undergo plastic deformation when subjected to external forces. This performance index reflects the ability of steel to resist permanent deformation. For high-quality carbon structural steel, the higher the yield strength, the stronger its ability to withstand external forces without permanent deformation. Therefore, yield strength ≥ 290MPa is a key indicator to ensure that steel has sufficient load-bearing capacity in application. Exemplarily, the yield strength can be 290MPa, 292MPa, 294MPa, 296MPa, 298MPa, 300MPa, etc.

[0059] Tensile strength is the maximum stress value that steel withstands in a tensile test, which reflects the ability of steel to resist fracture. The higher the tensile strength of high-quality carbon structural steel, the less likely it is to break when subjected to external forces. Therefore, tensile strength ≥ 410MPa is an important indicator to ensure that the steel has sufficient strength and durability in application. The tensile strength can be 410MPa, 412MPa, 414MPa, 416MPa, 418MPa, 420MPa, etc.

[0060] The elongation after fracture is the ratio of the elongation of steel after fracture in a tensile test to the original length, which reflects the plastic deformation capacity of steel. The higher this performance index is, the greater the plastic deformation of the steel can be without breaking when subjected to external force. Therefore, the elongation after fracture ≥ 36% is a key indicator to ensure that the steel has good toughness and deformation capacity in application. For example, the elongation after fracture can be 36%, 37%, 38%, 39%, 40%, etc.

[0061] Hardness is the ability of steel to resist local pressure deformation, which reflects the wear resistance and scratch resistance of steel. The higher the hardness of high-quality carbon structural steel, the less likely its surface will be scratched or worn. Therefore, hardness ≥ 125HV is an important indicator to ensure that the steel has sufficient wear resistance and service life in the application. Exemplarily, the hardness can be 125HV, 126HV, 127HV, 128HV, 129HV, 130HV, etc.

[0062] In summary, the embodiment of the present application optimizes the smelting and refining process and uses low-carbon ferrosilicon as a deoxidizer to replace part of the aluminum for deoxidation. This innovative strategy not only effectively reduces the formation of hard inclusions such as Al2O3, but also improves the purity and uniformity of the steel, providing reliable material guarantees for the production of high-performance, high-quality clutch transmission discs and other application products.

[0063] The present application is further described below in conjunction with specific embodiments. The experimental methods in the following embodiments that do not specify specific conditions are usually measured in accordance with national standards / industry standards; if there are no corresponding national standards / industry standards, they are measured in accordance with common international standards, conventional conditions, or conditions recommended by the manufacturer.

[0064] Example 1

[0065] The chemical composition of high-quality carbon structural steel includes: C0.12%, Si0.25%, Mn0.4%, P0.013%, S0.008%.

[0066] The preparation process of high-quality carbon structural steel includes: KR method hot metal desulfurization, BOF oxygen blowing steelmaking, RH refining and continuous casting. After the KR method desulfurization is completed, the mass fraction of S is 0.0007%; RH refining includes primary refining, LF furnace heating and RH secondary refining, Si killing is achieved by adding low-carbon ferrosilicon to increase Si, and low aluminum is achieved by reducing aluminum addition. The hot rolling process includes heating, rough rolling, finishing rolling, cooling and coiling. The heating furnace temperature is 1220℃, the intermediate billet thickness is 36mm, the finishing rolling initial temperature is 1050℃, the end temperature is 880℃, and the coiling temperature is 650℃.

[0067] The microstructure of the high-quality carbon structural steel produced in this embodiment is ferrite, the level of B-type alumina inclusions is 0, the level of A-type inclusions + B-type inclusions + C-type inclusions + D-type inclusions is 0.5, the yield strength is 299MPa, the tensile strength is 429MPa, the elongation after fracture is 37.5%, and the hardness is 130HV.

[0068] Example 2

[0069] The chemical composition of high-quality carbon structural steel includes: C0.13%, Si0.26%, Mn0.41%, P0.014%, S0.007%.

[0070] The preparation process of high-quality carbon structural steel includes: KR method hot metal desulfurization, BOF oxygen blowing steelmaking, RH refining and continuous casting. After the KR method desulfurization is completed, the mass fraction of S is 0.0005%; RH refining includes primary refining, LF furnace heating and RH secondary refining. Si sedation is achieved by adding low-carbon ferrosilicon to increase Si and by reducing aluminum addition to achieve low aluminum. The hot rolling process includes heating, rough rolling, finishing rolling, cooling and coiling. The heating furnace temperature is 1225℃, the intermediate billet thickness is 36mm, the finishing rolling initial temperature is 1040℃, the end temperature is 885℃, and the coiling temperature is 6450℃.

[0071] The microstructure of the high-quality carbon structural steel produced in this embodiment is ferrite, the level of B-type alumina inclusions is 0, the level of A-type inclusions + B-type inclusions + C-type inclusions + D-type inclusions is 0.5, the yield strength is 301MPa, the tensile strength is 435MPa, the elongation after fracture is 38%, and the hardness is 133HV.

[0072] Example 3

[0073] The chemical composition of high-quality carbon structural steel includes: C0.125%, Si0.24%, Mn0.4%, P0.015%, S0.009%.

[0074] The preparation process of high-quality carbon structural steel includes: KR method hot metal desulfurization, BOF oxygen blowing steelmaking, RH refining and continuous casting. After the KR method desulfurization is completed, the mass fraction of S is 0.0008%; RH refining includes primary refining, LF furnace heating and RH secondary refining, Si killing is achieved by adding low-carbon ferrosilicon to increase Si, and low aluminum is achieved by reducing aluminum addition. The hot rolling process includes heating, rough rolling, finishing rolling, cooling and coiling. The heating furnace temperature is 1215℃, the intermediate billet thickness is 36mm, the finishing rolling initial temperature is 1045℃, the end temperature is 878℃, and the coiling temperature is 640℃.

[0075] The microstructure of the high-quality carbon structural steel produced in this embodiment is ferrite, the level of B-type alumina inclusions is 0, the level of A-type inclusions + B-type inclusions + C-type inclusions + D-type inclusions is 0.5, the yield strength is 318MPa, the tensile strength is 441MPa, the elongation after fracture is 39%, and the hardness is 133HV.

[0076] It can be seen from Examples 1 to 3 that the chemical composition and preparation process of the examples are within the required range of the present invention, with yield strength ≥290 MPa, tensile strength ≥410 MPa, elongation after fracture ≥36%, hardness ≥125 HV, and low inclusion content.

[0077] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0078] The embodiment of the present invention innovatively uses Si to kill high-quality carbon structural steel, which can meet the low inclusion requirements of the clutch transmission plate and provide strong technical support for improving the overall performance of the clutch and extending its service life.

[0079] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. It will be apparent to those skilled in the art that various modifications to these embodiments are possible, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown in the present application, but will conform to the widest range consistent with the principles and novel features applied for by the present application.

Claims

1. A method for producing high-quality carbon structural steel using Si killing, the method comprising: The molten iron is sequentially subjected to KR desulfurization, BOF oxygen blowing, RH refining and continuous casting to obtain a slab with a set chemical composition; wherein the RH refining includes RH primary refining and RH secondary refining, and the RH primary refining uses low-carbon ferrosilicon as a deoxidizer; The slab is sequentially heated and roughly rolled to obtain an intermediate slab; The intermediate billet is sequentially subjected to finish rolling, cooling and coiling to obtain high-quality carbon structural steel.

2. The method according to claim 1, characterized in that In terms of mass fraction, the set chemical composition includes: C: 0.1% to 0.15%, Si: 0.2% to 0.3%, Mn: 0.3% to 0.5%, P≤0.02%, and S≤0.01%.

3. The method according to claim 1, characterized in that After the KR method desulfurization, the mass fraction of S is ≤0.001%.

4. The method according to claim 1, characterized in that: The heating furnace temperature is 1200°C to 1250°C.

5. The method according to claim 1, characterized in that: The thickness of the intermediate blank is 32 mm to 45 mm.

6. The method according to claim 1, characterized in that The initial temperature of the finish rolling is 1000°C to 1060°C, and the end temperature of the finish rolling is 860°C to 900°C.

7. The method according to claim 1, characterized in that The coiling temperature is 600°C to 660°C.

8. The method according to claim 1, characterized in that The microstructure of the high-quality carbon structural steel is mainly ferrite.

9. The method according to claim 1, characterized in that: The non-metallic inclusions of the high-quality carbon structural steel meet the following requirements: Class B inclusion level ≤ 0.5, Class A inclusion level + Class B inclusion level + Class C inclusion level + Class D inclusion level ≤ 1 level.

10. The method according to claim 1, characterized in that The high-quality carbon structural steel meets at least one of the following properties: yield strength ≥290MPa, tensile strength ≥410MPa, elongation after fracture ≥36%, and hardness ≥125HV.

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