HRB600 anti-seismic steel bar and production method thereof

Abstract

The production method of the HRB600 anti-seismic steel bar comprises the steps that a square billet is obtained through continuous casting, fluctuation is controlled to be smaller than or equal to 0.2 m / min, and the square billet comprises, by mass, 0.25 wt% or more of C and smaller than or equal to 0.28 wt%, 0.60 wt% or more of Si and smaller than or equal to 0.80 wt%, 1.40 wt% or more of Mn and smaller than or equal to 1.60 wt%, 0.05 wt% or more of Cr and smaller than or equal to 0.25 wt%, 0.11 wt% or more of V and smaller than or equal to 0.13 wt%, 0.010 wt% or more of Nb and smaller than or equal to 0.030 wt%, 0.020 wt% or more of N and smaller than or equal to 0.030 wt%, 0.045 wt% or less of P and 0.045 wt% or less of S; under the condition that the pulling speed of continuous casting is 3.2-3.6 m / min, the steel tapping mode of the square billet is direct rolling steel tapping; and the rough rolling temperature of the square billet obtained after direct rolling tapping is controlled to be 920-980 DEG C, and then the HRB600 anti-seismic steel bar is obtained through finish rolling treatment, finished product unit treatment and cooling bed cooling treatment. According to the production method, the production efficiency is remarkably improved, and the burnup cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of earthquake-resistant steel bars, and in particular to an HRB600 earthquake-resistant steel bar and a production method thereof. Background Art

[0002] After the introduction of GB 1499.2-2024 standard, the composition, performance and metallographic requirements were further standardized, and the production of water-piercing steel bars was restricted. High-strength HRB600 hot-rolled ribbed seismic steel bars are strengthened with higher contents of Nb and V microalloys. To ensure the strengthening effect, high heating and solution temperature requirements are required, resulting in low production efficiency, high fuel consumption and high rolling costs.

[0003] However, HRB600 steel bars produced by the commonly used direct rolling technology without heating not only have insufficient plasticity and toughness, but also have large fluctuations in product performance, resulting in some products failing to meet earthquake resistance requirements.

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

[0005] The main purpose of the present invention is to provide a HRB600 earthquake-resistant steel bar and a production method thereof, so as to solve the technical problems in the above-mentioned conventional technologies that high heating and solid solution temperature is required, resulting in low production efficiency, high fuel consumption and high rolling cost.

[0006] To achieve the above object, the present invention provides a method for producing HRB600 earthquake-resistant steel bars, comprising the steps of:

[0007] Continuously casting to obtain a square billet, controlling fluctuation ≤0.2 m / min, wherein 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%, 0.11wt%≤V≤0.13wt%, 0.010wt%≤Nb≤0.030wt%, 0.020wt%≤N≤0.030wt%, P≤0.045wt%, S≤0.045wt%, and the rest are iron and other inevitable impurities;

[0008] When the continuous casting speed is 3.2-3.6 m / min, the billet is tapped by direct rolling, the cutting temperature of the billet is 1020-1100° C., a heat preservation cover is provided in the continuous casting area, and the temperature drop from the billet to the front surface of the rolling mill is ≤100° C.;

[0009] The rough rolling temperature of the square billet produced by direct rolling is controlled at 920-980° C., and then the square billet is subjected to finish rolling, finished product unit treatment and cooling treatment on a cooling bed to obtain HRB600 earthquake-resistant steel bars.

[0010] Furthermore, when the continuous casting speed is less than 3.2 m / min, the billet is heated in a heating furnace after it comes off the production line, and the rough rolling temperature of the heated billet is controlled at 1020-1080°C, and then the billet is subjected to finish rolling, finished product unit treatment and cooling on a cooling bed to obtain HRB600 earthquake-resistant steel bars.

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

[0012] Furthermore, the temperature of the finished product when the finished product unit is processed is 940-1000°C.

[0013] Furthermore, the temperature of the cooling bed during the cooling treatment on the upper cooling bed is 940°C to 1000°C.

[0014] Furthermore, the cross-sectional dimension of the square billet is 165 mm*165 mm; the length of the square billet is 12000 mm.

[0015] Furthermore, the cooling treatment on the upper cooling bed also includes cold shearing to length treatment and sampling inspection treatment.

[0016] The present invention also provides an HRB600 earthquake-resistant steel bar produced by the production method as described in any one of the above items, characterized in that the metallographic phase of the HRB600 earthquake-resistant steel bar is ferrite + pearlite; the average grain diameter of the ferrite is 6 to 12 μm, and the grain size is 11.5 to 13.0; wherein the proportion of the ferrite is 50% to 60%, and the proportion of the pearlite is 40% to 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 earthquake-resistant steel bar is 12 mm to 25 mm.

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

[0020] The present invention provides a production method of HRB600 earthquake-resistant steel bars. Direct rolling of steel and controlling the rough rolling temperature at 900-960° C. can effectively match the production rhythm, significantly improve production efficiency, and reduce fuel consumption costs.

[0021] In order to maximize the product performance of the HRB600 earthquake-resistant steel bar worthy of the above process, the chemical composition and mass percentage of the square 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%, and the rest are iron and other inevitable impurities;

[0022] Among them: Carbon (C): content range is 0.25wt% ≤ C ≤ 0.28wt%. Carbon is one of the most important strengthening elements in steel, which can significantly improve the strength and hardness of steel. However, too high carbon content will reduce the plasticity and toughness of steel. 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, and improve the hardenability and hot working properties 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 range is 0.11wt%≤V≤0.13wt%. 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): The content range is 0.010wt% ≤ Nb ≤ 0.030wt%. Niobium can also refine the grains of steel and improve the strength and toughness of steel, especially at high temperatures.

[0028] Nitrogen (N): The content range is 0.020wt%≤N≤0.030wt%. 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 is limited to P ≤ 0.045wt% and S ≤ 0.045wt%. Phosphorus and sulfur are harmful elements in steel, which will reduce the plasticity and toughness of steel and increase the brittleness of steel. Therefore, their content needs to be strictly controlled.

[0030] The present invention aims to improve the strength, toughness, corrosion resistance and heat resistance of steel bars by adding appropriate amounts of alloying elements (such as carbon, silicon, manganese, chromium, vanadium, niobium and nitrogen). At the same time, by adding elements such as vanadium and niobium that refine grains, and in conjunction with carbon content control, the toughness and impact resistance of steel bars can be significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention 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, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0032] Figure 1 is the metallographic structure diagram of HRB600 prepared in Example 1 of the present invention;

[0033] Figure 2 is the metallographic structure diagram of HRB600 prepared in Example 3 of the present invention;

[0034] Figure 3 is the metallographic structure diagram of HRB600 prepared in Example 5 of the present invention;

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0039] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0040] The present invention provides a method for producing HRB600 earthquake-resistant steel bars, comprising the steps of:

[0041] S1. Continuously casting a square billet, wherein the casting speed is 3.2-3.6 m / min, and the fluctuation is controlled to be ≤0.2 m / min, to obtain a 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%, and the rest are iron and other inevitable impurities.

[0042] As an earthquake-resistant steel bar, the optimization of its chemical composition helps to improve its earthquake resistance, making it more suitable for structures with high requirements for earthquake resistance, such as high-rise buildings and bridges.

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

[0044] S2. The rough rolling temperature of the square billet produced by direct rolling is controlled at 920-980° C., and then the square billet is subjected to finish rolling, finished product unit processing and cooling on a cooling bed to obtain HRB600 earthquake-resistant steel bars.

[0045] Among them, the rough rolling temperature of 920~980℃ is the steel-out temperature of the lower billet during direct rolling.

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

[0047] A mode of complementary steelmaking between direct rolling and heating furnace is adopted. When the pulling speed at the beginning and end of the pouring is lower than 3.2m / min, the temperature of the billet is lower than the direct rolling temperature requirement. The billet is immediately hoisted into the heating furnace for insulation after it comes off the production line. This can effectively match the production rhythm, significantly improve production efficiency and reduce fuel consumption costs.

[0048] The above-mentioned direct rolling temperature can be 100°C lower than the steel-out temperature of the heating furnace because the micro-alloying elements V and Nb of the continuous casting billet precipitate less at high temperature, and the core temperature of the direct rolled billet is about 1000°C, which can basically maintain the same effect as the re-solid solution of alloy elements by heating in a heating furnace. In addition, the two different steel-out methods of direct rolling and heating furnace can adjust the amount of cooling water before finishing rolling to achieve basically the same finishing rolling temperature and upper cooling bed temperature, ensuring that the direct rolling performance is basically the same as the rolling performance of steel-out from a heating furnace.

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

[0050] Improve the plasticity of steel bars: By heating, the internal structure of the steel bars can be softened and its plasticity can be improved, making it easier to carry out subsequent processing such as rolling.

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

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

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

[0054] In some embodiments, the production specification of hot rolling can be ∮12mm to ∮25mm.

[0055] High-speed bar technology can be used to roll the material to be rolled efficiently and accurately to produce bar products that meet the requirements. High-speed bar production lines usually use advanced rolling technology and equipment, such as full short stress torsion-free rolling, multi-wire slitting technology, etc., to improve production efficiency and product quality.

[0056] In some embodiments, the finishing rolling temperature during the finishing rolling process may be 950-1010° C. A temperature above the upper limit is not conducive to grain refinement, while a temperature below the lower limit may result in premature precipitation of microalloys.

[0057] Double-wire slitting can be performed before pre-finishing rolling.

[0058] It should be noted that different cooling degrees can be used to ensure that the finishing rolling temperature, the temperature of the finished product and the temperature of the cooling bed are consistent for the two different steel-out methods of direct rolling and heating furnace.

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

[0060] In some embodiments, the cooling bed temperature during the upper cooling bed cooling treatment is 940°C to 1000°C. A temperature above the upper limit is not conducive to grain refinement, while a temperature below the lower limit will cause excessive cooling of the outer ring to form a semi-closed loop structure.

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

[0062] After the cooling treatment on the cooling bed, it can also include cold shearing to length treatment and sampling inspection treatment.

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

[0064] The yield strength of HRB600 earthquake-resistant steel bars is 620~660Mpa, the tensile strength is 770~870Mpa, 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.

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

[0066] Exemplarily, the diameter of the HRB600 earthquake-resistant steel bar may be 12 mm to 25 mm.

[0067] For easier understanding, here is an example:

[0068] The invention provides a production method of direct-rolled HRB600 straight seismic steel bars, the process comprising steelmaking-continuous casting-high-speed bar direct rolling / steel rolling from a heating furnace-controlled rolling and controlled cooling-cooling on a cooling bed-cold shearing to length-sampling and inspection-packaging and storage.

[0069] The present invention is further described below by specific embodiments 1 to 3:

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

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

[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 Parameters of rolling speed + rough rolling temperature + finishing rolling temperature + finished product temperature + upper cooling bed temperature + final rolling speed of each embodiment

[0074]

[0075] The other steps in Example 2 are the same as those in Example 1, except that the continuous casting speed is adjusted to less than 3.2 m / min, and direct rolling is replaced by the heating furnace steelmaking method.

[0076] The other steps in Example 4 are the same as those in Example 3, except that the continuous casting speed is adjusted to less than 3.2 m / min, and direct rolling is replaced by the heating furnace steelmaking method.

[0077] The other steps in Example 6 are the same as those in Example 5, except that the continuous casting speed is adjusted to less than 3.2 m / min, and direct rolling is replaced by steel tapping from a heating furnace.

[0078] Table 3 Mechanical properties of each embodiment

[0079]

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

[0081] The metallographic organization diagrams obtained in Example 1, Example 3 and Example 5 are shown in the attached drawings. Figure 1 , Attachment Figure 2 And attached Figure 3 shown.

[0082] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for producing HRB600 earthquake-resistant steel bars, characterized in that: Includes steps: Continuously casting to obtain a square billet, controlling fluctuation ≤0.2 m / min, wherein 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%, 0.11wt%≤V≤0.13wt%, 0.010wt%≤Nb≤0.030wt%, 0.020wt%≤N≤0.030wt%, P≤0.045wt%, S≤0.045wt%, and the rest are iron and other inevitable impurities; When the continuous casting speed is 3.2-3.6 m / min, the billet is tapped by direct rolling, the cutting temperature of the billet is 1020-1100° C., there is a heat preservation cover in the continuous casting area, and the temperature drop from the billet to the front surface of the rolling mill is ≤100° C.; The rough rolling temperature of the square billet produced by direct rolling is controlled at 920-980° C., and then the square billet is subjected to finish rolling, finished product unit treatment and cooling treatment on a cooling bed to obtain HRB600 earthquake-resistant steel bars.

2. The production method according to claim 1, characterized in that When the continuous casting speed is less than 3.2 m / min, the billet is heated in a heating furnace, and the rough rolling temperature of the heated billet is controlled at 1020-1080°C. The billet is then subjected to finish rolling, finished product unit treatment and cooling on a cooling bed to obtain HRB600 earthquake-resistant steel bars.

3. The production method according to claim 1, characterized in that The finishing rolling temperature during the finishing rolling treatment is 950 to 1010°C.

4. The method for producing HRB600 earthquake-resistant steel bars according to claim 4, characterized in that: The temperature of the finished product when the finished product unit is processed is 940-1000°C.

5. The method for producing HRB600 earthquake-resistant steel bars according to claim 4, characterized in that: The temperature of the cooling bed during the upper cooling bed cooling treatment is 940°C to 1000°C.

6. The method for producing HRB600 earthquake-resistant steel bars according to claim 4, characterized in that: The cross-sectional size of the square billet is 165 mm*165 mm; the length of the square billet is 12000 mm.

7. The method for producing HRB600 earthquake-resistant steel bars according to claim 4, characterized in that: The cooling process on the upper cooling bed also includes cold shearing to length processing and sampling and inspection processing.

8. A HRB600 earthquake-resistant steel bar produced by the production method according to any one of claims 1 to 7, characterized in that: The metallographic phase of the HRB600 earthquake-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; wherein the proportion of the ferrite is 50%-60%, and the proportion of the pearlite is 40%-50%.

9. The HRB600 earthquake-resistant steel bar according to claim 1, characterized in that: Yield strength 620~660Mpa, tensile strength 770~870Mpa, strength-to-yield ratio 1.25~1.30, yield-to-yield ratio 1.03~1.13, elongation after break 16.0%~20.0%, and total elongation after break at maximum force 10.0~12.

0.

10. The HRB600 earthquake-resistant steel bar according to claim 1, characterized in that: The diameter of the HRB600 earthquake-resistant steel bar is 12 mm to 25 mm.

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