Double-high-bar HRB400E reinforcing steel bar and production method thereof
Through the combination and smelting process of medium silicon, low manganese and vanadium microalloyation, double high rod HRB400E steel bars were prepared, solving the problems of insufficient seismic performance and high production costs of traditional steel bars, and achieving low-cost and high-performance steel bar production.
Patent Information
- Application Number
- CN202510018940.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-06
- Publication Date
- 2025-04-11
AI Technical Summary
Traditional building steel bars have shortcomings in seismic resistance, and the production cost of high-strength seismic resistance steel bars is high and the consumption of alloy resources is excessive, which is not conducive to the sustainable development of the economy and society.
Using a combination of medium silicon, low manganese and vanadium microalloyation, double high rod HRB400E steel bars were prepared by controlling chemical composition and smelting process. The microstructure was ferrite + pearlite, and the grain size and mechanical properties were in accordance with GB/T 1499.2-2018 standards.
The HRB400E steel bar with low production costs and ideal mechanical properties has been achieved, reducing the cost of alloys, especially when the price of silicon-manganese alloys increases, it has a greater cost advantage.
Smart Images
Figure CN119800220A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of threaded steel bars, and specifically relates to a double-high-rod HRB400E steel bar and a production method thereof. Background Art
[0002] With the increasing requirements for building structural safety and earthquake resistance, traditional building steel bars have deficiencies in earthquake resistance. Therefore, high-strength, high-performance earthquake-resistant steel bars such as HRB400E have gradually become the mainstream of the market. In addition, with the rapid development of national infrastructure construction, such as the increase in post-disaster reconstruction, bridges, highways, high-rise buildings and other projects, the demand for high-strength earthquake-resistant steel bars is also increasing. These factors have jointly promoted the research and development and widespread application of HRB400E steel bars.
[0003] HRB400E steel bars are mainly improved by increasing the content of alloy elements, such as vanadium-nitrogen alloying, and by adding alloy elements to improve the strength and toughness of steel bars. However, this will also increase the production cost of steel bars and excessive consumption of alloy resources, which is not conducive to the sustainable development of the economy and society. Summary of the invention
[0004] The present application provides a double-high-rod HRB400E steel bar and a production method, which can obtain HRB400E steel bars with low production cost and ideal mechanical properties, especially with cost advantages when the price of silicon-manganese alloys increases.
[0005] The first aspect of the present application provides a double-high-rod HRB400E steel bar, which includes the following chemical composition by mass percentage: C: 0.23-0.25%, Si: 0.35-0.45%, Mn: 0.70-0.80%, P≤0.040%, S≤0.040%, V: 0.018-0.028%, N: 0.012-0.018%, and the rest are Fe and trace elements.
[0006] Among them, W (Si+Mn) / W v Satisfy: 40 ≤ W (Si+Mn) / Wv≤60,W (Si+Mn) is the sum of the mass percentage of Si and the mass percentage of Mn, W v is the mass percentage of V.
[0007] In a feasible implementation manner of the first aspect of the present application, the microstructure of the double-high rod HRB400E steel bar is ferrite + pearlite; the volume fraction of ferrite is 66% to 75%, and 67% to 70% may be selected; the volume fraction of pearlite is 25% to 34%, and 31% to 33% may be selected.
[0008] In a feasible implementation manner of the first aspect of the present application, the average grain size of the double-high rod HRB400E steel bar is 4.65μm~8.83μm, and 6.67μm~8.04μm can be selected; the grain size is 11.0~12.5, and 11.5~12.0 can be selected.
[0009] In a feasible implementation of the first aspect of the present application, the yield strength of the double high bar HRB400E steel bar is 435-455Mpa, the tensile strength is 570-595Mpa, the strength-yield ratio is 1.27-1.39, the yield-yield ratio is 1.09-1.14, the elongation is 17-26%, and the maximum force total elongation is 12.9-16.0. The surface quality is smooth and the steel bar quality meets the requirements of GB / T 1499.2-2018 standard.
[0010] The second aspect of the present application provides a production method of double-high-bar HRB400E steel bars, comprising:
[0011] Obtaining raw materials with a predetermined mass percentage of chemical composition, smelting, casting, to obtain a steel billet; heating the steel billet, taking it out of the furnace, rolling, and cooling it to obtain double-high bar HRB400E steel; the heating temperature is ≤1150°C, the heating time is 40 to 80 minutes, and the steel tapping temperature is 900°C to 950°C;
[0012] The double high rod HRB400E steel bar includes the following chemical composition in mass percentage: C: 0.23-0.25%, Si: 0.35-0.45%, Mn: 0.70-0.80%, P≤0.040%, S≤0.040%, V: 0.018-0.028%, N: 0.012-0.018%, and the rest are Fe and trace elements.
[0013] In a feasible implementation manner of the second aspect of the present application, W (Si+Mn) / W v Satisfy: 40 ≤ W (Si+Mn) / Wv≤60,W (Si+Mn) is the sum of the mass percentage of Si and the mass percentage of Mn, W v is the mass percentage of V.
[0014] In a feasible implementation manner of the second aspect of the present application, in the step of obtaining a raw material with a predetermined mass percentage of chemical composition, smelting, and casting to obtain a steel billet, the smelting includes converter smelting and LF refining, wherein the converter smelting includes controlling the ladle bottom blowing argon gas flow rate at 50-100 Nm 3 / h, ferrosilicon and silicon-manganese alloy are added 1 minute after steel is tapped, vanadium-nitrogen or vanadium-containing pig iron and ferroniobium are added with the steel flow after half of the ferrosilicon and silicon-manganese alloy are added, and the addition is completed before the slag rod is thrown.
[0015] In a feasible implementation manner of the second aspect of the present application, in the step of obtaining a raw material with a predetermined mass percentage of chemical composition, smelting, and casting to obtain a steel billet, the smelting includes converter smelting and LF refining, wherein the LF refining includes controlling the ladle bottom blowing argon / nitrogen flow rate at 100-300 Nm 3 / h, add lime and slagging agent to control the binary basicity of the refined final slag to 2.5-3.5 to obtain refined molten steel.
[0016] In a feasible implementation manner of the second aspect of the present application, in the steps of obtaining raw materials with a predetermined mass percentage of chemical composition, smelting, and casting to obtain a steel billet, the physical and chemical properties of the protective slag used in the crystallizer during the casting process include: viscosity 0.15 poise to 0.26 poise at 1300°C, melting temperature 1070°C to 1110°C, and the protective slag includes the following compositions in mass percentage: SiO2: 28% to 37%, CaO: 22%-27%, K2O+Na2O: 8%-14%, F: 5%-9%, C solid: 8%-12%, and the rest are iron and trace elements.
[0017] In a feasible implementation manner of the second aspect of the present application, in the steps of obtaining raw materials with a predetermined mass percentage of chemical composition, smelting, and casting to obtain steel billets, the molten steel is subjected to secondary strong cooling in the crystallizer during the casting process, the water flow rates on the wide and narrow sides of the crystallizer are both 150t / h to 170t / h, and the specific water volume of the secondary cooling water is 1.4L / kg to 1.6L / kg.
[0018] In a feasible implementation manner of the second aspect of the present application, in the steps of heating, taking out of the furnace, rolling and cooling the steel billet to obtain double-high-rod HRB400E steel bars, the heating temperature of the steel billet is 50 to 100 minutes, the steel tapping temperature is 920 to 950°C, the finishing rolling temperature is 860 to 910°C, and the finished product temperature is 850°C to 900°C.
[0019] In a feasible implementation of the second aspect of the present application, the entire rolling line adopts full continuous rolling, and the rolling line is provided with 6 roughing mills, 4 intermediate mills, and 6 pre-finishing mills, all of which are short stress line mills without archways. The finishing mill group and the finished product mill both adopt a top-crossed 45° cantilever module mill, and adopt a 4+2 layout.
[0020] In a feasible implementation manner of the second aspect of the present application, in the step of heating, taking out of the furnace, rolling and cooling the steel billet to obtain double-high-rod HRB400E steel bars, the temperature of the cooling bed on the steel bars is controlled to be 820°C to 860°C, the cooling rate is 3.0°C / s to 4.0°C / s, and the temperature difference from the start of rolling to the upper cooling bed is controlled within 120°C. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1It is an electron microscope image of the metallographic structure 500X of the double-high bar HRB400E hot-rolled ribbed steel bar shown in Example 1;
[0022] Figure 2 is an electron microscope image of the metallographic structure 500X of the double-high bar HRB400E hot-rolled ribbed steel bar shown in Example 2;
[0023] Figure 3 This is an electron microscope image of the metallographic structure 500X of the double-high rod HRB400E hot-rolled ribbed steel bar shown in Example 3. DETAILED DESCRIPTION
[0024] In order to make the invention purpose, technical scheme and beneficial technical effect of the present application clearer, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the embodiments described in this specification are only for explaining the present application, not for limiting the present application.
[0025] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range, and any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, although not explicitly stated, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.
[0026] In the description herein, when a composition is described as containing, comprising or including specific components, or when a process is described as containing, comprising or including specific process steps, it is expected that the composition of the present application also consists essentially of or consists of the components, and the process of the present application also consists essentially of or consists of the process steps.
[0027] The use of the terms "including," "comprising," "containing," and "having" should generally be interpreted as open ended and non-limiting unless expressly stated otherwise.
[0028] In the description of this article, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number itself, and the “multiple” in “one or more” means more than two.
[0029] The above-mentioned summary of the invention of the present application is not intended to describe each disclosed embodiment or each implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided by a series of examples, which can be used in various combinations. In each example, enumeration is only used as a representative group and should not be interpreted as exhaustive.
[0030] The inventors found that HRB400E steel bars are usually composed of C, Si, Mn, Cr, V, P, S, N, Fe and other trace elements. After the introduction of GB / T 1499.2-2018, the composition, performance and metallographic requirements were further standardized, and new requirements were put forward for the production process, metallographic structure and strength level of steel bars. In order to meet the standards, most steel mills use Nb, V, Cr and other micro-alloys to strengthen hot-rolled ribbed steel bars. Although the strength can meet the requirements, the alloy cost is still high.
[0031] In view of this, the inventor provides a double-high-rod HRB400E steel bar and a production method in the present application, which can obtain HRB400E steel bars with low production cost and ideal mechanical properties, especially when the price of silicon-manganese alloys increases, which has a cost advantage.
[0032] In the implementation of the first aspect of the present application, a double-high-rod HRB400E steel bar is provided, and the double-high-rod HRB400E steel bar comprises the following chemical composition by mass percentage: C: 0.23-0.25%, Si: 0.35-0.45%, Mn: 0.70-0.80%, P≤0.040%, S≤0.040%, V: 0.018-0.028%, N: 0.012-0.018%, and the rest are Fe and trace elements,
[0033] Among them, W (Si+Mn) / W v Satisfy: 40 ≤ W (Si+Mn) / Wv≤60,W (Si+Mn) is the sum of the mass percentage of Si and the mass percentage of Mn, W v is the mass percentage of V.
[0034] In the HRB400E steel bar of the present invention, a combination of medium silicon, low manganese and vanadium microalloying is adopted, the mass percentage of silicon and manganese is at a relatively low level, and it is strengthened with microalloyed vanadium of appropriate mass percentage, which is beneficial to reduce the cost of steel bars as a whole and can make the mechanical properties of HRB400E steel bars more ideal, effectively reducing the alloy cost by more than 10 yuan / ton of steel, especially the W in the HRB400E steel bar of the present invention. (Si+Mn) / W v Satisfy: 40 ≤ W (Si+Mn) / W v ≤60, which makes it have more cost advantages when the price of silicon-manganese alloys rises higher and the price of vanadium alloys is lower, and can improve the competitiveness of products.
[0035] In some embodiments, the microstructure of the double high rod HRB400E steel bar is ferrite + pearlite; the volume fraction of ferrite is 66% to 75%, and 67% to 70% can be selected; the volume fraction of pearlite is 25% to 34%, and 31% to 33% can be selected. In this application, ferrite + pearlite has a suitable volume fraction so that the HRB400E steel bar has a suitable organizational structure, so that the HRB400E steel bar has good mechanical properties.
[0036] In some embodiments, the average grain size of the double-high-bar HRB400E steel bar is 4.65 μm to 8.83 μm, and 6.67 μm to 8.04 μm can be selected; the grain size is 11.0 to 12.5, and 11.5 to 12.0 can be selected. In this application, the HRB400E steel bar has a suitable average grain size and grain size as shown in the above range, which can balance the requirements of strength, toughness, cold bending performance and other aspects of the material to meet the needs of different engineering applications.
[0037] In some embodiments, the yield strength of the double high bar HRB400E steel bar is 435-455Mpa, the tensile strength is 570-595Mpa, the strength-to-yield ratio is 1.27-1.39, the yield-to-yield ratio is 1.09-1.14, the elongation is 17-26%, and the maximum force total elongation is 12.9-16.0. The surface quality is smooth and the steel bar quality meets the requirements of GB / T 1499.2-2018 standard.
[0038] In an embodiment of the second aspect of the present application, a method for producing double-high-bar HRB400E steel bars is provided, comprising:
[0039] Obtaining raw materials with a predetermined mass percentage of chemical composition, smelting, casting, to obtain a steel billet; heating the steel billet, taking it out of the furnace, rolling, and cooling it to obtain double-high bar HRB400E steel; the heating temperature is ≤1150°C, the heating time is 40 to 80 minutes, and the steel tapping temperature is 900°C to 950°C;
[0040] The double high rod HRB400E steel bar includes the following chemical composition in mass percentage: C: 0.23-0.25%, Si: 0.35-0.45%, Mn: 0.70-0.80%, P≤0.040%, S≤0.040%, V: 0.018-0.028%, N: 0.012-0.018%, and the rest are Fe and trace elements.
[0041] In some embodiments, W (Si+Mn) / W v Satisfy: 40 ≤ W (Si+Mn) / Wv≤60,W (Si+Mn) is the sum of the mass percentage of Si and the mass percentage of Mn, W vis the mass percentage of V.
[0042] In some embodiments, in the step of obtaining a raw material with a predetermined mass percentage of chemical composition, smelting, and casting to obtain a steel billet, the smelting includes converter smelting and LF refining, wherein the converter smelting includes controlling the flow rate of argon gas at the bottom of the ladle to be 50-100 Nm 3 / h, ferrosilicon and silicon-manganese alloy are added 1 minute after steel is tapped, vanadium-nitrogen or vanadium-containing pig iron and ferroniobium are added with the steel flow after half of the ferrosilicon and silicon-manganese alloy are added, and the addition is completed before the slag rod is thrown.
[0043] In some embodiments, in the step of obtaining a raw material with a predetermined mass percentage of chemical composition, smelting, and casting to obtain a steel billet, the smelting includes converter smelting and LF refining, wherein the LF refining includes controlling the ladle bottom blowing argon / nitrogen flow rate at 100-300 Nm 3 / h, add lime and slagging agent to control the binary basicity of the refined final slag to 2.5-3.5 to obtain refined molten steel.
[0044] In some embodiments, in the steps of obtaining raw materials with a predetermined mass percentage of chemical composition, smelting, and casting to obtain a steel billet, the physical and chemical properties of the protective slag used in the crystallizer during the casting process include: viscosity of 0.15 poise to 0.26 poise at 1300°C, melting temperature of 1070°C to 1110°C, and the protective slag includes the following mass percentage compositions: SiO2: 28% to 37%, CaO: 22%-27%, K2O+Na2O: 8%-14%, F: 5%-9%, C solid: 8%-12%, and the rest are iron and trace elements.
[0045] In some embodiments, in the steps of obtaining raw materials with a predetermined mass percentage of chemical composition, smelting, and casting to obtain steel billets, the molten steel is subjected to secondary strong cooling in the crystallizer during the casting process, the water flow rates on the wide and narrow sides of the crystallizer are both 150 t / h to 170 t / h, and the specific water volume of the secondary cooling water is 1.4 L / kg to 1.6 L / kg.
[0046] In some embodiments, in the step of heating the steel billet, taking out of the furnace, rolling, and cooling to obtain double-high-bar HRB400E steel bars, the heating temperature of the steel billet is 50 to 100 minutes, the steel tapping temperature is 920°C to 950°C, the finishing rolling temperature is 860°C to 910°C, and the finished product temperature is 850°C to 900°C.
[0047] In some embodiments, the entire rolling line adopts full continuous rolling, and the rolling line is equipped with 6 roughing mills, 4 intermediate mills, and 6 pre-finishing mills, all of which are short stress line mills without archways. The finishing mill group and the finished product mill both adopt top-crossed 45° cantilever module mills, and adopt a 4+2 layout.
[0048] In some embodiments, in the step of heating, taking out of the furnace, rolling, and cooling the steel billet to obtain double-high-rod HRB400E steel bars, the temperature of the cooling bed on the steel bars is controlled to be 820°C to 860°C, the cooling rate is 3.0°C / s to 4.0°C / s, and the temperature difference from the start of rolling to the upper cooling bed is controlled within 120°C.
[0049] The HRB400E steel bar in this application is combined with the appropriate preparation process in some of the above embodiments, so that the HRB400E steel bar has better organizational structure, mechanical properties and cold bending performance.
[0050] Example
[0051] The following examples more specifically describe the disclosure of the present application, which are intended for illustrative purposes only, as it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the disclosure of the present application. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.
[0052] The present invention is further described below by means of specific examples 1-6.
[0053] Example 1
[0054] A preparation method of double high bar HRB400E hot rolled ribbed steel bar, comprising: blast furnace molten iron → converter smelting → LF refining → billet continuous casting → heating furnace heating → rough rolling → intermediate rolling → finishing rolling → controlled cooling → multiple length shearing → cooling on a cooling bed → cold shearing to length → finishing → packaging → weighing → warehousing;
[0055] Obtaining raw materials with a predetermined mass percentage of chemical composition, smelting, and casting to obtain a steel billet; the smelting includes converter smelting and LF refining, wherein the converter smelting includes controlling the ladle bottom blowing argon gas flow rate at 78Nm 3 / h, ferrosilicon and silicon-manganese alloy are added 1 minute after steel is tapped, vanadium nitrogen or vanadium-containing pig iron and ferroniobium are added with the steel flow after half of ferrosilicon and silicon-manganese alloy are added, and the addition is completed before the slag rod is thrown. LF refining includes controlling the argon / nitrogen flow rate of the ladle bottom blowing at 80Nm 3 / h, add lime and slagging agent, the refining time is 37min, and the binary basicity of the refined final slag is controlled to be 2.3 to obtain refined molten steel; the refined molten steel is cast, and the physical and chemical properties of the protective slag used in the crystallizer during the casting process include: viscosity 0.2 poise at 1300℃, melting temperature 1080℃, and the protective slag includes the composition of mass percentage: SiO2: 30%, CaO: 25%), K2O+Na2O: 10%, F: 6%, C solid: 10%, and the rest are iron and trace elements; during the casting process, the molten steel is subjected to secondary strong cooling at the crystallizer, and the water flow rates of the wide and narrow sides of the crystallizer are both 160t / h; the specific water volume of the secondary cooling water is: 1.5L / kg.
[0056] The billet is transported to the heating furnace for heating and discharged from the furnace. The outlet temperature of the steel is measured at the exit of the 6# frame. After the billet is discharged from the furnace, the entire rolling line adopts full continuous rolling. The rolling line is equipped with 6 roughing mills, 4 intermediate rolling mills, and 6 pre-finishing mills, all of which are short stress line mills without archways. The finishing mill group and the finished product mill both adopt the top-crossing 45° cantilever module mill, and adopt the 4+2 layout. The rolling specifications are ∮12mm~∮20mm. The steel bars are cooled in the air cooling of the cooling bed, and the produced rebars are sampled and inspected, and then sheared, packaged, and stored to obtain double-high-bar HRB400E steel bars.
[0057] Embodiment 2-3
[0058] The differences between Examples 2 to 3 and Example 1 are shown in Tables 1 to 4 below.
[0059] Embodiments 4 to 6
[0060] The compositions of the steel bars of Examples 4 to 6 are the same as those of Example 3, and the different parameters in the preparation process are shown in Tables 1 to 4 below.
[0061] Table 1 Chemical composition of steel bars in Examples 1 to 3
[0062]
[0063] Table 2 Process parameters in the steelmaking process of each embodiment
[0064]
[0065] Table 3 Process parameters during rolling of each embodiment
[0066]
[0067]
[0068] Table 4 Steel structure parameters of each embodiment
[0069]
[0070] The performance of the double-high rod HRB400E hot-rolled ribbed steel bars obtained in each embodiment was tested, and the test results are shown in Table 5 below.
[0071] Table 5 Performance test results of steel in various examples
[0072]
[0073] It can be seen from the data in the table that the metallographic structure and surface quality of the HRB400E hot-rolled ribbed steel bars produced in the embodiments of the present application fully meet the requirements of GB / T 1499.2-2018, effectively reducing the alloy cost by more than 10 yuan / ton of steel, and in the case of price increases of silicon-manganese alloy, the alloy cost can be reduced by more than 20 yuan / ton of steel. Among them, the performance of Example 1 is slightly worse than that of Examples 2 to 3 due to the small nitrogen flow rate in refining and smelting, the basicity of the final slag in refining is small, and the nitrogen content in the finished steel product is low. Example 4 has a small water volume of the secondary cooling water and a large water flow rate in the crystallizer, so there is a risk of steel leakage during casting. Example 5 has a high temperature on the upper cooling bed and a slow cooling rate, so the performance is slightly worse than that of Examples 2 to 3. Example 6 has a low billet tapping temperature and a high finished product temperature, and the outer ring has a semi-closed loop fine grain structure.
[0074] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.
Claims
1. A double high bar HRB400E steel bar, characterized in that: The double high rod HRB400E steel bar includes the following chemical composition by mass percentage: C: 0.23-0.25%, Si: 0.35-0.45%, Mn: 0.70-0.80%, P≤0.040%, S≤0.040%, V: 0.018-0.028%, N: 0.012-0.018%, and the rest is Fe and trace elements; Among them, W (Si+Mn) / W v Satisfy: 40 ≤ W (Si+Mn) / W v ≤60; W (Si+Mn) is the sum of the mass percentage of Si and the mass percentage of Mn, W v is the mass percentage of the V.
2. The double high rod HRB400E steel bar according to claim 1, characterized in that: The microstructure of the double-high-bar HRB400E steel bar is ferrite+pearlite; the volume fraction of the ferrite is 66% to 75%, and can be 67% to 70%; the volume fraction of the pearlite is 25% to 34%, and can be 31% to 33%.
3. The double high rod HRB400E steel bar according to claim 1, characterized in that: The average grain size of the double-high rod HRB400E steel bar is 4.65 μm to 8.83 μm, and can be 6.67 μm to 8.04 μm; the grain size is 11.0 to 12.5, and can be 11.5 to 12.
0.
4. A production method of double high rod HRB400E steel bar, characterized in that: include: Obtaining raw materials with a predetermined mass percentage of chemical composition, smelting, and casting to obtain steel billets; The steel billet is heated, discharged from a furnace, rolled, and cooled to obtain double-high bar HRB400E steel; the heating temperature is ≤1150°C, the heating time is 40-80 minutes, and the discharge temperature is 900°C-950°C; The double-high-rod HRB400E steel bar includes the following chemical composition in percentage by mass: C: 0.23-0.25%, Si: 0.35-0.45%, Mn: 0.70-0.80%, P≤0.040%, S≤0.040%, V: 0.018-0.028%, N: 0.012-0.018%, and the rest are Fe and trace elements.
5. The production method of double high rod HRB400E steel bar according to claim 4, characterized in that: In the step of obtaining raw materials with a predetermined mass percentage of chemical composition, smelting, and casting to obtain a steel billet, the smelting includes converter smelting and LF refining, wherein the converter smelting includes controlling the flow rate of argon gas at the bottom of the ladle to be 50-100 Nm 3 / h, ferrosilicon and silicon-manganese alloy are added 1 minute after steel is tapped, vanadium-nitrogen or vanadium-containing pig iron and ferroniobium are added with the steel flow after half of the ferrosilicon and silicon-manganese alloy are added, and the addition is completed before the slag rod is thrown.
6. The production method of double high rod HRB400E steel bar according to claim 4, characterized in that: In the step of obtaining a raw material with a predetermined mass percentage of chemical composition, smelting, and casting to obtain a steel billet, the smelting includes converter smelting and LF refining, wherein the LF refining includes controlling the flow rate of argon / nitrogen blowing at the bottom of the ladle to be between 100 and 300 Nm 3 / h, add lime and slagging agent to control the binary basicity of the refined final slag to 2.5-3.5 to obtain refined molten steel.
7. The production method of double high rod HRB400E steel bar according to claim 4, characterized in that: In the steps of obtaining raw materials with a predetermined mass percentage of chemical composition, smelting, and casting to obtain a steel billet, the physical and chemical properties of the protective slag used in the crystallizer during the casting process include: viscosity of 0.15 poise to 0.26 poise at 1300°C, melting temperature of 1070°C to 1110°C, and the protective slag includes the following mass percentage compositions: SiO2: 28% to 37%, CaO: 22% to 27%, K2O+Na2O: 8% to 14%, F: 5% to 9%, C solid: 8% to 12%, and the rest are iron and trace elements.
8. The method for producing double-high-rod HRB400E steel bars according to claim 4, characterized in that: In the steps of obtaining raw materials with a predetermined mass percentage of chemical composition, smelting, and casting to obtain steel billets, the molten steel is subjected to secondary strong cooling at the crystallizer during the casting process, the water flow rates of the wide and narrow sides of the crystallizer are both 150t / h to 170t / h, and the specific water volume of the secondary cooling water is 1.4L / kg to 1.6L / kg.
9. The method for producing double-high-rod HRB400E steel bars according to claim 4, characterized in that: In the steps of heating the steel billet, taking out of the furnace, rolling and cooling to obtain double-high-bar HRB400E steel bars, the heating temperature of the steel billet is 50min-100min, the steel tapping temperature is 920℃-950℃, the finishing rolling temperature is 860℃-910℃, and the finished product temperature is 850℃-900℃.
10. The production method of double-high-rod HRB400E steel bars according to claim 4, characterized in that: In the step of heating, taking out of the furnace, rolling and cooling the steel billet to obtain double-high-bar HRB400E steel bars, the temperature of the cooling bed on the steel bars is controlled to be 820°C to 860°C, the cooling rate is 3.0°C / s to 4.0°C / s, and the temperature difference from the start of rolling to the upper cooling bed is controlled within 120°C.