Hrb600 anti-vibration steel bar and its production method

Abstract

This invention provides an HRB600 seismic-resistant steel bar and its production method. The production method of the HRB600 seismic-resistant steel bar includes the following steps: continuous casting to obtain a square billet, controlling the fluctuation ≤0.2m / min, and the chemical composition and mass percentage of the square billet are 0.25wt%≤C≤0.28wt%, 0.60wt%≤Si≤0.80wt%, 1.40wt%≤Mn≤1.60wt%, 0.05wt%≤Cr≤0.25wt%, and 0.11wt%≤V≤0. The composition is as follows: 0.13wt%, 0.010wt%≤Nb≤0.030wt%, 0.020wt%≤N≤0.030wt%, P≤0.045wt%, S≤0.045wt%. Under continuous casting speeds of 3.2-3.6 m / min, the billet is tapped by direct rolling. The roughing temperature of the directly rolled billet is controlled at 920-980℃, followed by finishing rolling, finished product processing, and cooling on a cooling bed to obtain HRB600 seismic-resistant steel bars. This invention significantly improves production efficiency and reduces fuel costs.

Description

Technical Field

[0001] This invention relates to the field of earthquake-resistant steel reinforcement, and more particularly to an HRB600 earthquake-resistant steel reinforcement and its production method. Background Technology

[0002] After the release of the GB 1499.2-2024 standard, the requirements for composition, performance and metallographic structure were further standardized, which restricted the production of water-resistant steel bars. High-strength HRB600 hot-rolled ribbed earthquake-resistant steel bars are reinforced with high content of Nb and V microalloying. In order to ensure the strengthening effect, the heating and solution treatment temperature is required to be high, which leads to low production efficiency, high fuel consumption and high rolling cost.

[0003] HRB600 steel bars produced by the commonly used non-heated direct rolling production technology not only suffer from insufficient plasticity and toughness, but also exhibit large fluctuations in product performance, resulting in some products failing to meet seismic requirements.

[0004] Based on the above, it is urgent to study HRB600 seismic-resistant steel bars and their production methods in order to solve the above problems. Summary of the Invention

[0005] The main objective of this invention is to provide an HRB600 seismic-resistant steel bar and its production method, in order to solve the technical problems of high heating and solution treatment temperature requirements, resulting in low production efficiency, high fuel consumption, and high rolling costs in the commonly used technologies mentioned above.

[0006] To achieve the above objectives, the present invention provides a method for producing HRB600 seismic-resistant steel bars, comprising the following steps:

[0007] The billet is obtained by continuous casting, with fluctuation controlled to ≤0.2m / min. The chemical composition and mass percentage of the billet are as follows: 0.25wt%≤C≤0.28wt%, 0.60wt%≤Si≤0.80wt%, 1.40wt%≤Mn≤1.60wt%, 0.05wt%≤Cr≤0.25wt%, 0.11wt%≤V≤0.13wt%, 0.010wt%≤Nb≤0.030wt%, 0.020wt%≤N≤0.030wt%, P≤0.045wt%, S≤0.045wt%, with the remainder being iron and other unavoidable impurities.

[0008] When the continuous casting speed is 3.2-3.6 m / min, the billet is tapped by direct rolling, the billet is cut at 1020-1100℃, the continuous casting area is covered with a heat insulation cover, and the surface temperature drop of the billet before it reaches the rolling mill is ≤100℃.

[0009] The roughing temperature of the square billet produced by the direct rolling process is controlled at 920-980℃, followed by finishing rolling, finished product processing, and cooling on an upper cooling bed to obtain HRB600 seismic-resistant steel bars.

[0010] Furthermore, when the continuous casting speed is less than 3.2 m / min, the billet enters the heating furnace for heating after exiting the line. The rough rolling temperature of the billet after heating is controlled at 1020-1080℃. Then, after finishing rolling, finished product unit processing, and cooling on the upper cooling bed, HRB600 seismic steel bars are obtained.

[0011] Furthermore, the finishing temperature during the finishing rolling process is 950–1010°C.

[0012] Furthermore, the temperature of the finished product during the processing of the finished product unit is 940-1000℃.

[0013] Furthermore, the temperature of the cooling bed during the upper cooling bed cooling process is 940℃~1000℃.

[0014] Furthermore, the cross-sectional dimensions of the billet are 165mm*165mm; the length of the billet is a fixed length of 12000mm.

[0015] Furthermore, the cooling process after the upper cooling bed also includes cold shearing for length determination and sampling inspection.

[0016] The present invention also provides an HRB600 seismic-resistant steel bar produced by any of the above-described production methods, characterized in that the metallographic structure of the HRB600 seismic-resistant steel bar is ferrite + pearlite; the average grain diameter of the ferrite is 6-12 μm, and the grain size is 11.5-13.0 grade; wherein the proportion of ferrite is 50%-60%, and the proportion of pearlite is 40%-50%.

[0017] Furthermore, the yield strength is 620–660 MPa, the tensile strength is 770–870 MPa, the strength-to-yield ratio is 1.25–1.30, the yield-to-yield ratio is 1.03–1.13, the elongation after fracture is 16.0%–20.0%, and the total elongation after fracture at maximum force is 10.0%–12.0%.

[0018] Furthermore, the diameter of the HRB600 seismic-resistant steel bar is 12mm to 25mm.

[0019] The beneficial effects of this invention are as follows:

[0020] This invention provides a method for producing HRB600 earthquake-resistant steel bars. Direct rolling and controlling the rough rolling temperature at 900-960℃ can effectively match the production rhythm, significantly improve production efficiency, and reduce fuel costs.

[0021] To ensure the highest possible performance of the HRB600 seismic-resistant steel bars produced by the above-mentioned process, the chemical composition and mass percentage of the billet material are controlled as follows: 0.25wt%≤C≤0.28wt%, 0.60wt%≤Si≤0.80wt%, 1.40wt%≤Mn≤1.60wt%, 0.05wt%≤Cr≤0.25wt%, 0.11wt%≤V≤0.13wt%, 0.010wt%≤Nb≤0.030wt%, 0.020wt%≤N≤0.030wt%, P≤0.045wt%, S≤0.045wt%, with the remainder being iron and other unavoidable impurities.

[0022] Carbon (C): its content ranges from 0.25 wt% ≤ C ≤ 0.28 wt%. Carbon is one of the most important strengthening elements in steel, significantly improving its strength and hardness. However, excessively high carbon content can reduce the steel's plasticity and toughness. Within this range, the carbon content is precisely controlled to balance strength and toughness.

[0023] Silicon (Si): Content range is 0.60wt% ≤ Si ≤ 0.80wt%. Silicon is mainly used as a deoxidizer, which can significantly improve the strength and hardness of steel, and also helps to improve the heat resistance and corrosion resistance of steel.

[0024] Manganese (Mn): Content range is 1.40wt% ≤ Mn ≤ 1.60wt%. Manganese is an important alloying element in steel, which can significantly improve the strength and hardness of steel, while also improving the hardenability and hot workability of steel.

[0025] Chromium (Cr): Content range is 0.05wt% ≤ Cr ≤ 0.25wt%. Chromium is mainly used to improve the corrosion resistance and heat resistance of steel, and can also improve the strength and hardness of steel to a certain extent.

[0026] Vanadium (V): Content ranges from 0.11 wt% ≤ V ≤ 0.13 wt%. Vanadium is a strong carbide-forming element that can significantly improve the strength and toughness of steel, especially through grain refinement and precipitation strengthening mechanisms.

[0027] Niobium (Nb): Content ranges from 0.010 wt% to 0.030 wt%. Niobium can also refine the grain structure of steel, improving its strength and toughness, especially at high temperatures.

[0028] Nitrogen (N): Content ranges from 0.020 wt% ≤ N ≤ 0.030 wt%. Nitrogen exists in steel mainly in the form of nitrides, which can refine grains and improve the strength and wear resistance of steel.

[0029] Phosphorus (P) and sulfur (S): The content of both is limited to P ≤ 0.045 wt% and S ≤ 0.045 wt%. Phosphorus and sulfur are harmful elements in steel, which reduce the plasticity and toughness of steel and increase its brittleness. Therefore, their content needs to be strictly controlled.

[0030] This invention aims to improve the strength, toughness, corrosion resistance, and heat resistance of reinforcing steel bars by adding appropriate amounts of alloying elements (such as carbon, silicon, manganese, chromium, vanadium, niobium, and nitrogen). Simultaneously, by adding grain-refining elements such as vanadium and niobium, and in conjunction with controlled carbon content, the toughness and impact resistance of the reinforcing steel bars are significantly improved. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0032] Figure 1 The image shows the metallographic structure of HRB600 obtained in Example 1 of this invention.

[0033] Figure 2 The image shows the metallographic structure of HRB600 obtained in Example 3 of this invention.

[0034] Figure 3 The metallographic structure of HRB600 obtained in Example 5 of this invention is shown.

[0035] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] It should be noted that all directional indicators (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0038] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0039] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0040] This invention provides a method for producing HRB600 seismic-resistant steel bars, comprising the following steps:

[0041] S1. A square billet is obtained by continuous casting at a casting speed of 3.2-3.6 m / min, with fluctuations controlled to ≤0.2 m / min, to obtain the material to be rolled; the chemical composition and mass percentage of the square billet material are 0.25wt%≤C≤0.28wt%, 0.60wt%≤Si≤0.80wt%, 1.40wt%≤Mn≤1.60wt%, 0.05wt%≤Cr≤0.25wt%, 0.11wt%≤V≤0.13wt%, 0.010wt%≤Nb≤0.030wt%, 0.020wt%≤N≤0.030wt%, P≤0.045wt%, S≤0.045wt%, with the remainder being iron and other unavoidable impurities.

[0042] As a seismic-resistant steel bar, the optimization of its chemical composition helps to improve its seismic performance, making it more suitable for high-rise buildings, bridges and other structures with high seismic performance requirements.

[0043] By adjusting the chemical composition of the steel bars (i.e., straight-rolled HRB600E straight seismic steel bars, hereinafter the same), and then optimizing the appropriate processing technology, the chemical composition and the process are coordinated to obtain straight-rolled HRB600 straight seismic steel bars with good strength in a way with low fuel consumption and high production efficiency.

[0044] S2. The roughing temperature of the square billet produced by direct rolling is controlled at 920-980℃, and then it undergoes finishing rolling, finished product processing and cooling on an upper cooling bed to obtain HRB600 seismic steel bars.

[0045] Among them, the roughing temperature of 920-980℃ is the tapping temperature of the billet below the direct rolling tapping.

[0046] In some embodiments, when the casting speed in step S1 is less than 3.2 m / min, the billet enters a heating furnace for heating after being rolled off the line, and the rough rolling temperature of the billet after heating and tapping is controlled at 1020 to 1080°C.

[0047] By adopting a complementary model of direct rolling and hot furnace steel output, when the casting speed at the beginning and end of the casting cycle is less than 3.2m / min, the billet temperature is lower than the direct rolling temperature requirement. After being arranged to come off the line, it is immediately hoisted into the hot furnace for heat preservation, which can effectively match the production rhythm, significantly improve production efficiency, and reduce fuel costs.

[0048] The reason why the direct rolling temperature can be 100°C lower than the furnace exit temperature is that the microalloying elements V and Nb in the continuously cast billet precipitate less at high temperatures, and the core temperature of the direct-rolled billet is about 1000°C, which can basically maintain the same effect as the furnace heating to resolidify the alloying elements. In addition, the two different exit methods of direct rolling and furnace can adjust the amount of cooling water before entering the finishing mill to make the temperature of entering the finishing mill and the temperature of the upper cooling bed basically the same, ensuring that the performance of direct rolling and the rolling performance of furnace exit are basically the same.

[0049] In the commonly used techniques, heating in the furnace is a crucial step in the processing of HRB600 seismic-resistant steel bars. The heating temperature range is between 1120℃ and 1250℃, and its necessity is mainly reflected in the following aspects:

[0050] Improving the plasticity of steel bars: Heating can soften the internal structure of steel bars, increasing their plasticity and making them easier to process in subsequent processes such as rolling.

[0051] Uniform steel temperature: The heating furnace can ensure that the temperature of the steel bar is uniform along its entire length, avoiding performance differences caused by uneven temperature during the rolling process.

[0052] Relieving internal stress: During the heating process, the internal stress of the steel bar is released, which helps to reduce deformation and cracks during processing.

[0053] Improving steel properties: Appropriate heating temperature and time can optimize the mechanical properties of steel bars, such as increasing strength and toughness.

[0054] In some embodiments, the production specifications for hot rolling can be ∮12mm~∮25mm.

[0055] High-speed bar technology can be used to efficiently and precisely roll materials to produce bar products that meet requirements. High-speed bar production lines typically employ advanced rolling technologies and equipment, such as full short-stress twist-free rolling and multi-wire cutting technology, to improve production efficiency and product quality.

[0056] In some embodiments, the finishing temperature during the finishing rolling process can be 950–1010°C. Temperatures above the upper limit are not conducive to grain refinement, while temperatures below the lower limit can lead to premature precipitation of microalloys.

[0057] Double-line cutting can be performed before pre-finishing rolling.

[0058] It should be noted that different cooling levels can be used to keep the finishing temperature, the temperature of the finished product, and the temperature of the upper cooling bed consistent for two different steel output methods: direct rolling and heating furnace.

[0059] In some embodiments, the temperature of the finished product during the finished product unit processing is 940 to 1000°C. Temperatures above the upper limit are not conducive to grain refinement, while temperatures below the lower limit will cause premature precipitation of microalloys.

[0060] In some embodiments, the cooling bed temperature during the upper cooling bed cooling process is 940°C to 1000°C. Temperatures above the upper limit are not conducive to grain refinement, while temperatures below the lower limit will lead to excessive cooling of the outer ring, resulting in a semi-closed-loop structure.

[0061] In some embodiments, the cross-sectional dimensions of the billet are 165mm*165mm; the length of the billet is a fixed length of 12000mm.

[0062] After cooling on a cooling bed, the process may also include cold shearing to length and sampling inspection.

[0063] The present invention also provides an HRB600 seismic-resistant steel bar produced by any of the above-described production methods, characterized in that the metallographic structure of the HRB600 seismic-resistant steel bar is ferrite + pearlite; the average grain diameter of the ferrite is 6-10 μm, and the grain size is 11.5-13.0 grade; wherein the proportion of ferrite is 50%-60%, and the proportion of pearlite is 40%-50%.

[0064] HRB600 seismic-resistant steel bars have a yield strength of 620–660 MPa, a tensile strength of 770–870 MPa, a strength-to-yield ratio of 1.25–1.30, a yield-to-yield ratio of 1.03–1.13, an elongation after fracture of 16.0%–20.0%, and a total elongation after fracture at maximum force of 10.0%–12.0%.

[0065] For example, the metallographic structure is F+P, and both the mechanical properties and metallographic structure meet the GB 1499.2-2024 standard and seismic requirements.

[0066] For example, the diameter of HRB600 seismic-resistant steel bars can be 12mm to 25mm.

[0067] To make it easier to understand, here is an example:

[0068] This invention provides a method for producing HRB600 straight anti-seismic steel bars by direct rolling. The process includes steelmaking, continuous casting, high-speed direct rolling of bar stock / rolling of steel from a heating furnace, controlled rolling and cooling, cooling on a cooling bed, cold shearing to length, sampling and inspection, and packaging and warehousing.

[0069] The present invention will be further described below through specific embodiments 1 to 3:

[0070] Examples 1, 3, and 5 respectively produced three specifications of HRB600 hot-rolled ribbed steel bars with diameters of ∮14mm, ∮20mm, and ∮25mm. The chemical composition by mass percentage (wt%) is shown in Table 1, with the remainder being residual elements in the molten steel. The drawing speed, temperature control, and final rolling speed are shown in Table 2. The mechanical property and plate shape measurement results are shown in Table 3.

[0071] Table 1. Chemical composition (wt%, balance Fe) of each embodiment.

[0072] Example C Si Mn Cr P S Nb V Ceq 1 0.28 0.65 1.53 0.12 0.028 0.020 0.018 0.115 0.56 3 0.27 0.68 1.48 0.14 0.020 0.035 0.020 0.122 0.55 5 0.26 0.66 1.46 0.06 0.025 0.022 0.019 0.126 0.54 National Standard ≤0.28 ≤0.80 ≤1.60 - ≤0.045 ≤0.045 - - ≤0.58

[0073] Table 2. Rolling speed, roughing temperature, temperature before finishing mill, temperature before finished product, temperature before cooling bed, and final rolling speed parameters for each embodiment.

[0074]

[0075] In Example 2, the other steps are the same as in Example 1, except that when the casting speed is adjusted to <3.2m / min, direct rolling is replaced by steel tapping from a heated furnace.

[0076] In Example 4, the other steps are the same as in Example 3, except that when the casting speed is adjusted to <3.2m / min, direct rolling is replaced by steel tapping from a heated furnace.

[0077] In Example 6, the other steps are the same as in Example 5, except that when the continuous casting speed is adjusted to <3.2m / min, direct rolling is replaced by steel tapping from a heated furnace.

[0078] Table 3 Mechanical properties of each embodiment

[0079]

[0080] Examples 1, 3, and 5 show that HRB600 produced by a direct rolling matching heating furnace has stable temperature control, good surface quality, and its mechanical properties and metallographic properties fully meet the requirements of GB 1499.2-2024.

[0081] The metallographic structures obtained in Examples 1, 3, and 5 are shown in the attached figures. Figure 1 Appendix Figure 2 and appendix Figure 3 As shown.

[0082] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for producing HRB600 seismic-resistant steel bars, characterized in that, Including the following steps: The billet is obtained by continuous casting, with fluctuation controlled to ≤0.2m / min. The chemical composition and mass percentage of the billet are 0.25wt%≤C≤0.28wt%, 0.60wt%≤Si≤0.80wt%, 1.40wt%≤Mn≤1.60wt%, 0.06wt%≤Cr≤0.25wt%, 0.11wt%≤V≤0.13wt%, 0.010wt%≤Nb≤0.030wt%, 0.020wt%≤N≤0.030wt%, P≤0.045wt%, S≤0.045wt%, with the remainder being iron and other unavoidable impurities. When the continuous casting speed is 3.2-3.6 m / min, the billet is tapped by direct rolling, the billet cutting temperature is 1020-1100℃, the continuous casting area is equipped with a heat insulation cover, and the surface temperature drop of the billet before reaching the rolling mill is ≤100℃; the rough rolling temperature of the billet tapped by direct rolling is controlled at 920~980℃, and then it undergoes finishing rolling, finished product unit processing and cooling on an upper cooling bed to obtain HRB600 seismic steel bars; Alternatively, if the casting speed of the continuous casting is less than 3.2 m / min, the billet is sent to a heating furnace for heating after it is removed from the line. The rough rolling temperature of the billet after heating is controlled at 1020~1080℃. Then, after finishing rolling, finishing unit processing and cooling on a cooling bed, HRB600 seismic steel bars are obtained. The finishing temperature during the finishing rolling process is 950~1010℃, the finished product temperature during the finished product unit process is 940~1000℃, and the cooling bed temperature during the upper cooling bed cooling process is 940℃~1000℃. The HRB600 seismic-resistant steel bars have a yield strength of 620~660 MPa, a tensile strength of 770~870 MPa, a strength-to-yield ratio of 1.25~1.30, a yield-to-yield ratio of 1.03~1.13, an elongation after fracture of 16.0%~20.0%, and a total elongation after fracture at maximum force of 10.0~12.0%.

2. The method for producing HRB600 seismic-resistant steel bars according to claim 1, characterized in that, The cross-sectional dimension of the billet is 165mm. 165mm; the length of the billet is a fixed length of 12000mm.

3. The method for producing HRB600 seismic-resistant steel bars according to claim 1, characterized in that, The cooling process on the upper cooling bed also includes cold shearing for length determination and sampling inspection.

4. An HRB600 seismic-resistant steel bar produced by the production method according to any one of claims 1 to 3, characterized in that, The metallographic structure of the HRB600 seismic-resistant steel bar is ferrite + pearlite; the average grain diameter of the ferrite is 6~12µm and the grain size is 11.5~13.0 grade; wherein, the proportion of ferrite is 50%~60% and the proportion of pearlite is 40%~50%.

5. The HRB600 seismic-resistant steel bar according to claim 4, characterized in that, The diameter of the HRB600 seismic-resistant steel bars is 12mm~25mm.

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