HRB600E high-strength aseismic steel bar, preparation method and application

Abstract

The invention provides an HRB600E high-strength anti-seismic reinforcing steel bar, a preparation method and application, and the HRB600E high-strength anti-seismic reinforcing steel bar comprises the following chemical components in percentage by mass: 0.2 to 0.4 percent of C, 1.5 to 3.0 percent of Mn, 0.5 to 1.7 percent of Si, 0.01 to 0.3 percent of V, 0.01 to 0.1 percent of Nb, 0.01 to 0.05 percent of N, 0.01 to 0.605 percent of Al, Plt and the balance of Fe. 0.01%, Slt; 0.003%, and the balance being Fe and inevitable impurity elements. Wherein the yield strength is larger than or equal to 620 MPa, and the yield-strength ratio is larger than or equal to 1.25. The method is simple in process step and convenient to operate, the production cost is reduced, it is guaranteed that the surface smoothness of the manufactured steel bar is high, and the method is suitable for large-scale industrial production. The prepared HRB600E high-strength anti-seismic steel bar has good application in the aspect of improving the anti-seismic property in a building structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel rolling, and in particular relates to an HRB600E high-strength earthquake-resistant steel bar, a preparation method and an application thereof. Background Art

[0002] As a key reinforcement material for building structures, hot-rolled rebar's performance directly determines the safety and economic efficiency of construction projects. This has driven the continuous evolution of high-strength rebar for construction toward higher strength, superior toughness and ductility, and excellent weldability. HRB600E high-strength seismic rebar, due to its high strength, high strength-to-yield ratio, and excellent ductility, is considered a core representative of the new generation of green building steel.

[0003] In the field of metal material rolling and forming, the post-rolling cooling process is the core link for regulating the microstructure and mechanical properties of the material. The traditional water cooling process achieves rapid cooling by direct water cooling after rolling. Although the process is simple, the non-equilibrium phase transformation caused by rapid cooling easily generates martensite or local tempered structure, making the carbonitride precipitation phase uneven in size, making it difficult to balance strength and toughness, and the number density is low, resulting in poor stability of mechanical properties. In addition, due to the concentration of thermal stress during the cooling stage, it is easy to induce surface oxide scale peeling, affecting the surface finish of the steel bar and increasing production costs. In response to the above problems, a HRB600E high-strength earthquake-resistant steel bar, a preparation method and application are proposed. Summary of the Invention

[0004] The main purpose of the present invention is to provide a HRB600E high-strength earthquake-resistant steel bar, a preparation method and an application, aiming to solve the technical problems in the prior art of uneven size distribution of carbonitride precipitation phase, insufficient surface cleanliness and poor mechanical property stability.

[0005] To achieve the above objectives, the present invention provides an HRB600E high-strength earthquake-resistant steel bar, the chemical composition of the HRB600E high-strength earthquake-resistant steel bar, calculated by mass percentage, including: C 0.2-0.4%, Mn 1.5-3.0%, Si 0.5-1.7%, V 0.01-0.3%, Nb 0.01-0.1%, N 0.01-0.05%, Al 0.01-0.605%, P <0.01%, S <0.003%, and the balance being Fe and unavoidable impurity elements.

[0006] The yield strength of the HRB600E high-strength earthquake-resistant steel bar is ≥620MPa, and the strength-to-yield ratio is ≥1.25.

[0007] According to an embodiment of the present application, the structure of the precipitation phase of the HRB600E high-strength earthquake-resistant steel bar is ferrite and pearlite.

[0008] According to the embodiment of the present application, the particle size of the precipitated phase is 2 to 4.5 nm; the number density is 1600 to 2500 nm. -2 .

[0009] This application also proposes a method for preparing HRB600E high-strength earthquake-resistant steel bars, comprising the following steps:

[0010] The steel billet is heated to a first temperature at a rate of 10 to 20° C. / s and then kept at this temperature for 120 to 300 seconds to obtain a fully austenitized steel billet; the chemical composition of the steel billet is the same as that of HRB600E high-strength earthquake-resistant steel bars.

[0011] The austenitized steel billet is first cooled to a first deformation temperature, and first kept warm, and then rolled to obtain a first deformed steel billet.

[0012] The first deformed steel billet is subjected to a second cooling process to a second deformation temperature, and is subjected to a second heat preservation process, and is rolled to obtain a second deformed steel billet.

[0013] The second deformed steel billet is cooled to room temperature through a third cooling process to obtain the HRB600E high-strength earthquake-resistant steel bar.

[0014] Wherein, the first temperature is 1150-1300°C.

[0015] According to an embodiment of the present application, the first cooling rate is 5-20°C / s, the second cooling rate is 5-20°C / s, and the third cooling rate is 0.5-20°C / s.

[0016] According to an embodiment of the present application, the first heat preservation time is 30 to 60 seconds, and the second heat preservation time is 30 to 60 seconds.

[0017] According to an embodiment of the present application, the first deformation temperature is 1000-1200°C, and the second deformation temperature is 1000-1100°C.

[0018] According to an embodiment of the present application, the deformation amount of the first deformed steel billet obtained after rolling is 30%, and the deformation amount of the second deformed steel billet obtained after rolling is 40%.

[0019] According to the embodiment of the present application, the deformation rates of the first deformed steel billet and the second deformed steel billet are 5 to 20s respectively. -1 .

[0020] The HRB600E high-strength earthquake-resistant steel bar or the HRB600E high-strength earthquake-resistant steel bar prepared by the above-mentioned method is used to improve the earthquake resistance of building structures.

[0021] The beneficial effects of the present invention are:

[0022] The HRB600E high-strength earthquake-resistant steel bar described in this invention has a suitable chemical composition and content. Among them, the yield strength is ≥620 MPa and the strength-to-yield ratio is ≥1.25. The performance of the HRB600E high-strength earthquake-resistant steel bar is guaranteed by the addition of alloying elements such as C, Mn, Si, V, Nb, and Al.

[0023] The above process is simple and easy to operate, reducing production costs while ensuring a smooth surface finish. This method is suitable for large-scale industrial production. The resulting HRB600E high-strength earthquake-resistant steel bar is well-suited for improving the seismic performance of building structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0025] Figure 1 Schematic diagram of the process for simulating the rolling and cooling process for this application;

[0026] Figure 2 Optical microscope images of HRB600E high-strength seismic-resistant steel bars obtained at different third cooling rates in Example 1; (a) 0.5°C / s, (b) 1°C / s, (c) 3°C / s, (d) 5°C / s, (e) 8°C / s, (f) 10°C / s, (g) 12°C / s, (h) 15°C / s, and (i) 20°C / s;

[0027] Figure 3 TEM images of the precipitated phase in polygonal ferrite at different third cooling rates; (a) 0.5℃ / s, (b) 1℃ / s, (c) 3℃ / s, (d) 5℃ / s;

[0028] Figure 4 Figure 2 shows the particle size (a) and number density statistics (b) of the nano-precipitated phase in HRB600E high-strength seismic steel bars at different cooling rates.

[0029] The realization of the objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] The following will be combined with the accompanying 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 embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0031] Moreover, 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 ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0032] To achieve the above objectives, the present invention provides an HRB600E high-strength earthquake-resistant steel bar, the chemical composition of the HRB600E high-strength earthquake-resistant steel bar, calculated by mass percentage, including: C 0.2-0.4%, Mn 1.5-3.0%, Si 0.5-1.7%, V 0.01-0.3%, Nb 0.01-0.1%, N 0.01-0.05%, Al 0.01-0.605%, P <0.01%, S <0.003%, and the balance being Fe and unavoidable impurity elements.

[0033] The yield strength of the HRB600E high-strength earthquake-resistant steel bar is ≥620MPa, and the strength-to-yield ratio is ≥1.25.

[0034] In some embodiments, niobium refines the grain size, improving the steel's strength and toughness. Vanadium further enhances the steel's strength through solid solution strengthening and precipitation strengthening. The addition of nitrogen reduces vanadium usage, lowering production costs while also improving the steel's strength and toughness. By incorporating niobium, vanadium, and nitrogen microalloying elements, HRB600E high-strength seismic rebar achieves a yield strength of ≥620 MPa and a strength-to-yield ratio of ≥1.25, ensuring excellent performance even under extreme conditions such as earthquakes.

[0035] In some embodiments, the precipitated phase of the HRB600E high-strength earthquake-resistant steel bar comprises ferrite and pearlite.

[0036] In some embodiments, ferrite is an interstitial solid solution formed by carbon dissolving in the interstitial spaces of the α-Fe lattice and has a body-centered cubic structure. The grains of ferrite are generally distributed in an equiaxed polygonal pattern and have good plasticity and toughness. Pearlite is a mechanical mixture of ferrite and cementite and is a eutectic transformation product of steel. The mechanical properties of pearlite are between those of ferrite and cementite, with high strength, moderate hardness, and certain plasticity. In HRB600E high-strength earthquake-resistant steel bars, ferrite can improve the plasticity and toughness of the steel bars, while pearlite provides higher strength. The organizational characteristics and distribution of ferrite and pearlite have a significant effect on the performance of steel bars, thereby improving the comprehensive performance of steel bars.

[0037] In some embodiments, the particle size of the precipitated phase is 2 to 4.5 nm; the number density is 1600 to 2500 nm. -2 .

[0038] In some embodiments, regulating the particle size and number density of precipitated phases in steel bars can significantly improve the strength, toughness, and corrosion resistance of the bars, while also optimizing microstructural uniformity and processing performance, and reducing production costs. For example, a small precipitate particle size can effectively hinder dislocation motion, inhibit grain growth, and refine grain size, thereby increasing the yield strength and tensile strength of the material. By controlling the particle size and number density of precipitated phases, elemental segregation can be reduced, the chemical composition uniformity of the material can be improved, and residual stress can be reduced, thereby improving the mechanical properties.

[0039] The HRB600E high-strength seismic rebar has a suitable chemical composition and alloying elements, with a yield strength of 620 MPa or higher and a strength-to-yield ratio of 1.25 or higher. The addition of alloying elements such as C, Mn, Si, V, Nb, and Al ensures the HRB600E's high-strength seismic rebar maintains excellent performance even under extreme conditions such as earthquakes.

[0040] This application also proposes a method for preparing HRB600E high-strength earthquake-resistant steel bars, comprising the following steps:

[0041] S1: The steel billet is heated to a first temperature at a rate of 10-20°C / s, and then held at that temperature for 120-300 seconds to obtain a fully austenitized steel billet. The chemical composition of the steel billet is the same as that of HRB600E high-strength earthquake-resistant steel bar. The first temperature is 1150-1300°C.

[0042] In some embodiments, a thermomechanical simulation test machine was used to simulate the rolling and cooling processes. A steel billet with the same chemical composition as HRB600E high-strength seismic steel bar was heated at a rate of 10-20°C / s to a first temperature of 1150-1300°C, followed by a holding time of 120-300 seconds to obtain a fully austenitized steel billet. By controlling the heating rate and holding time, complete austenitization of the steel billet can be achieved.

[0043] S2: Cooling the austenitized steel billet to a first deformation temperature, performing a first heat preservation, and rolling to obtain a first deformed steel billet.

[0044] In some embodiments, the fully austenitized billet is cooled to a first deformation temperature of 1000-1200°C at a predetermined first cooling rate (e.g., 5°C / s) to allow for sufficient recrystallization of the austenite and refinement of the particles, thereby ensuring uniform distribution and stability of the austenite grains. A first heat preservation step is then performed to ensure uniformity of the internal and external temperatures of the material. This heat preservation treatment can effectively reduce temperature gradients, avoid thermal stress and deformation caused by internal and external temperature differences, and improve the quality of the final product. Rolling is then performed at the first deformation temperature to ensure uniformity of the deformation process, resulting in a first deformed billet.

[0045] S3: Cooling the first deformed steel billet to a second deformation temperature, performing a second heat preservation, and rolling to obtain a second deformed steel billet.

[0046] In some embodiments, the first deformed steel billet is subjected to a second cooling step to a second deformation temperature of 1000-1100° C., followed by a second holding step to partially recrystallize the austenite and introduce dislocations, thereby providing high-density nucleation sites for the precipitation of nanoscale carbonitrides. The second deformed steel billet is then rolled.

[0047] S4: Cooling the second deformed steel billet to room temperature through a third cooling step to obtain the HRB600E high-strength earthquake-resistant steel bar.

[0048] In some embodiments, the second deformed steel billet is subjected to a third cooling step to room temperature. By controlling the third cooling rate, the particle size and number density of the nano-precipitated phase in the HRB600E high-strength earthquake-resistant steel bar are effectively regulated. This effectively improves the mechanical properties and production stability of the HRB600E high-strength earthquake-resistant steel bar while reducing costs.

[0049] In some embodiments, the microstructure of the second deformed steel billet is ferrite with white contrast and pearlite with black contrast.

[0050] The above-mentioned method for preparing HRB600E high-strength earthquake-resistant steel bars utilizes a controlled rolling and cooling process to control the post-rolling composition and cooling rate using a steel billet with appropriate chemical composition and content, resulting in a macroscopic metallographic structure that meets the requirements for HRB600E high-strength earthquake-resistant steel bars. This method features simple process steps, convenient operation, reduced production costs, and ensures a high surface finish for the resulting steel bars. The method is suitable for large-scale industrial production.

[0051] In some embodiments, the first cooling rate is 5-20° C. / s, the second cooling rate is 5-20° C. / s, and the third cooling rate is 0.5-20° C. / s.

[0052] In some specific embodiments, the first cooling rate is 10° C. / s, the second cooling rate is 10° C. / s, and the third cooling rate is 0.5° C. / s. The corresponding cooling rates are controlled by controlling the amount and intensity of cooling water.

[0053] In some embodiments, after rolling, the second deformed steel billet is required to be subjected to a third cooling process to room temperature, and the rate of the third cooling process is controlled to ensure the microstructure and performance of the HRB600E high-strength earthquake-resistant steel bar. Controlling the rate of the third cooling process can achieve uniform cooling, so that the particle size of the nano-precipitated phase is 2 to 4.5 nm and the number density is 1600 to 2500 nm. -2 If the third cooling rate is too high, the amount of precipitated phase decreases and the corresponding particle size of precipitated phase increases.

[0054] In some embodiments, the first insulation time is 30 to 60 seconds, and the second insulation time is 30 to 60 seconds.

[0055] To ensure uniform temperature inside and outside the material, in some embodiments, a holding step is typically included during the heating or cooling process to ensure uniform temperature inside and outside the material, reduce temperature gradients, and avoid thermal stress and deformation caused by internal and external temperature differences. The holding time is selected based on the material size, composition, and process requirements and is not specifically limited, as long as the internal and external temperatures are uniform.

[0056] According to an embodiment of the present application, the first deformation temperature is 1000-1200°C, and the second deformation temperature is 1000-1100°C.

[0057] In some embodiments, the first deformation temperature is 1000-1200° C., and the second deformation temperature is 1000-1100° C. The first deformation temperature and the second deformation temperature are controlled to achieve rolling at different temperatures to obtain the HRB600E high-strength earthquake-resistant steel bar described in this application.

[0058] In some embodiments, the deformation amount of the first deformed steel billet obtained after rolling is 30%, and the deformation amount of the second deformed steel billet obtained after rolling is 40%.

[0059] In some embodiments, the deformation of the first deformed steel billet after rolling is 30%, which can reduce the size of the steel billet by 30%. If the thickness of the steel billet is 100 mm, the thickness of the first deformed steel billet after rolling is 70 mm. By regulating the deformation of the first steel billet, the size of the steel billet can be quickly reduced, which is beneficial to subsequent rolling and processing. The deformation of the second deformed steel billet is 40%, which further reduces the size of the steel billet by 40% on the basis of the first deformed steel billet. If the thickness of the first deformed steel billet is 70 mm, the thickness of the second deformed steel billet is 42 mm. Through rolling, the density and uniformity of the material are improved, and rapid forming and performance optimization of the steel billet are achieved.

[0060] In some embodiments, the deformation rates of the first deformed steel billet and the second deformed steel billet are 5 to 20 seconds respectively. -1 .

[0061] In some embodiments, the deformation rates of the first deformed steel billet and the second deformed steel billet are controlled to be 5-20s respectively. -1 , which can effectively optimize the microstructure and mechanical properties of the material. Among them, the deformation rate of the first deformed steel billet and the deformation rate of the second deformed steel billet can be appropriately adjusted according to the specific material and process.

[0062] The HRB600E high-strength earthquake-resistant steel bar or the HRB600E high-strength earthquake-resistant steel bar produced by the aforementioned method is used to improve the seismic performance of building structures. Due to its high strength, HRB600E high-strength earthquake-resistant steel bar can reduce steel usage without compromising structural safety, thereby lowering construction costs. Furthermore, its excellent plastic deformation capacity allows it to absorb energy during earthquakes through its own deformation, reducing structural deformation and damage during earthquakes. This improves the overall stability and load-bearing capacity of buildings, making it an indispensable and important material in modern building structures.

[0063] For further understanding of the present invention, now illustrate with examples:

[0064] Example 1

[0065] The chemical composition of the HRB600E high-strength earthquake-resistant steel bar, calculated by mass percentage, includes C: 0.27%, Mn: 1.55%, Si: 0.73%, V: 0.152%, Nb: 0.015%, N: 0.022%, P < 0.01%, S < 0.003%, and the balance is Fe and unavoidable impurity elements.

[0066] A Gleeble-1500D testing machine was used to simulate the rolling and cooling process. A steel billet with the same chemical composition as that of HRB600E high-strength earthquake-resistant steel bar was heated to 1220°C at a rate of 10°C / s and then kept at this temperature for 180s to complete the austenitization of the steel billet.

[0067] The fully austenitized steel billet is cooled to the first deformation temperature of 1100°C at a first cooling rate of 10°C / s, and the first heat preservation is carried out for 30s. The deformation rate of the first deformation steel billet is adjusted to 10s -1 After rolling, the deformation of the first deformed steel billet is 30%.

[0068] Then, the first deformed billet is cooled to the second deformation temperature of 1050°C at a second cooling rate of 10°C / s, and the second heat preservation is carried out for 30s. The deformation rate of the second deformed billet is adjusted to 10s -1 After rolling, the deformation of the second deformed steel billet is 40%.

[0069] Finally, the third cooling rate was controlled to be 0.5°C / s to cool the steel bar to room temperature, thereby obtaining the HRB600E high-strength earthquake-resistant steel bar.

[0070] According to the test, the yield strength of the HRB600E high-strength earthquake-resistant steel bar is 630MPa, the strength-to-yield ratio is 1.29, the structure is ferrite and pearlite, the average diameter of the nano-precipitates is 4nm, and the average number density is 1860nm. -2 .

[0071] Example 2

[0072] Compared with Example 1, the third cooling rate was changed to 1° C. / s.

[0073] According to the test, the yield strength of the HRB600E high-strength earthquake-resistant steel bar is 640MPa, the strength-to-yield ratio is 1.27, the structure is ferrite and pearlite, the average diameter of the nano-precipitates is 3.5nm, and the average number density is 2450nm. -2 .

[0074] Example 3

[0075] Compared with Example 1, the third cooling rate was changed to 3° C. / s.

[0076] According to the test, the yield strength of the HRB600E high-strength earthquake-resistant steel bar is 645MPa, the strength-to-yield ratio is 1.28, the structure is ferrite, pearlite and a small amount of bainite, the average diameter of the nano-precipitates is 2.5nm, and the average number density is 2300nm. -2 .

[0077] Example 4

[0078] Compared with Example 1, the third cooling rate was changed to 5° C. / s.

[0079] According to the test, the yield strength of the HRB600E high-strength earthquake-resistant steel bar is 655MPa, the strength-to-yield ratio is 1.26, the structure is ferrite, pearlite and a small amount of bainite, the average diameter of the nano-precipitates is 3.0nm, and the average number density is 1700nm. -2 .

[0080] Comparative Example 1

[0081] Compared with Example 1, the second deformation temperature is changed to 900°C.

[0082] The test results show that the yield strength of the steel bar is 660MPa, the strength-to-yield ratio is 1.23, the structure is ferrite and pearlite, the average diameter of the nano-precipitates is 5nm, and the average number density is 1950nm. -2 .

[0083] in, Figure 1 Schematic diagram of the process for simulating the rolling and cooling process for this application; Figure 2 Optical microscope images of HRB600E high-strength seismic-resistant steel bars obtained at different third cooling rates in Example 1; (a) 0.5°C / s, (b) 1°C / s, (c) 3°C / s, (d) 5°C / s, (e) 8°C / s, (f) 10°C / s, (g) 12°C / s, (h) 15°C / s, and (i) 20°C / s; Figure 3 TEM images of the precipitated phase in polygonal ferrite at different third cooling rates; (a) 0.5℃ / s, (b) 1℃ / s, (c) 3℃ / s, (d) 5℃ / s; Figure 4 Figure 2 shows the particle size (a) and number density statistics (b) of the nano-precipitated phase in HRB600E high-strength seismic steel bars at different cooling rates.

[0084] Depend on Figure 2 (a) and Figure 2 (b) It can be seen that as the third cooling rate increases from 0.5℃ / s to 1℃ / s, the microstructure of HRB600E high-strength seismic steel bar is composed of ferrite with white contrast and pearlite with black-brown contrast. Figure 2 (c) It can be seen that when the third cooling rate is 3℃ / s, the pearlite grain size and content are significantly reduced, and the ferrite grain size is gradually refined. Figure 2 (d) It can be seen that when the third cooling rate increases to 5℃ / s, the pearlite grain size and content further decrease, and the bainite phase variable gradually increases. Figure 2 (e) It can be seen that when the third cooling rate increases to 8℃ / s, pearlite basically disappears, martensite begins to form, and ferrite transforms from a mixed structure of polygonal intragranular ferrite and grain boundary ferrite to a network grain boundary ferrite. Figure 2 (f)~ Figure 2 (i) It can be seen that when the third cooling rate increases to 10℃ / s-20℃ / s, the microstructure is dominated by martensite, and the proportion of grain boundary ferrite and bainite gradually decreases. Different matrix microstructures can be obtained at different cooling rates.

[0085] Depend on Figure 3 It can be seen that when the third cooling rate is 0.5°C / s to 5°C / s, a high-density nanoscale fine precipitate phase is obtained. Figure 4 Figure 1 shows the particle size (a) and number density (b) of the nano-precipitates in HRB600E high-strength seismic rebar at different third cooling rates. The diameter and number density of the (V, Nb)(C, N) precipitates are affected only by the third cooling rate after rolling. Increasing the third cooling rate after rolling increases the driving force for nucleation of the (V, Nb)(C, N) precipitates and the nucleation rate.

[0086] Depend on Figure 4 (a) and Figure 4 (b) As can be seen, at the third cooling rate of 0.5°C / s, the (V, Nb)(C, N) nano-precipitates are numerous, with a number density of 1861.91 μm and a relatively large diameter, with an average diameter of 4.15 nm. At the third cooling rate of 1°C / s, the number of (V, Nb)(C, N) nano-precipitates increases, reaching 2453.36 μm, and their diameter is relatively large, with an average diameter of 3.27 nm. This fully meets the structural requirements of steel bars. It can be seen that when the third cooling rate increases from 0.5°C / s to 1°C / s, the number density of the precipitates increases, while the diameter decreases. This is because the increased third cooling rate increases the nucleation rate of (V, Nb)(C, N). Simultaneously, its growth behavior is suppressed, resulting in a reduction in size. When the third cooling rate increases from 1°C / s to 3°C / s or 5°C / s, the nucleation driving force increases, but this cannot compensate for the decreased diffusion rate of the microalloying elements. Therefore, the increase in the third cooling rate reduces the amount of precipitated phases, and due to the uneven distribution of microalloying elements, the diameter of the precipitated phase increases slightly at 5℃ / s.

[0087] The present invention ensures the performance of HRB600E high-strength earthquake-resistant steel bars by adding alloying elements such as C, Mn, Si, V, Nb, and Al. The appropriate chemical composition and content are also regulated. The yield strength of HRB600E high-strength earthquake-resistant steel bars is ≥620 MPa, and the strength-to-yield ratio is ≥1.25. Furthermore, the process steps are simple, the operation is convenient, the production cost is reduced, and the surface finish of the steel bars obtained is ensured to be high. This method is suitable for large-scale industrial production. The obtained HRB600E high-strength earthquake-resistant steel bars have good applications in improving the earthquake resistance of building structures.

[0088] In summary, the above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description 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 HRB600E high-strength earthquake-resistant steel bar, characterized in that: The chemical composition of the HRB600E high-strength earthquake-resistant steel bar, in terms of mass percentage, includes: C 0.2-0.4%, Mn 1.5-3.0%, Si 0.5-1.7%, V 0.01-0.3%, Nb 0.01-0.1%, N 0.01-0.05%, Al 0.01-0.605%, P < 0.01%, S < 0.003%, and the balance is Fe and unavoidable impurity elements; The yield strength of the HRB600E high-strength earthquake-resistant steel bar is ≥620MPa, and the strength-to-yield ratio is ≥1.

25.

2. The HRB600E high-strength earthquake-resistant steel bar according to claim 1, characterized in that: The precipitated phase of the HRB600E high-strength earthquake-resistant steel bar consists of ferrite and pearlite.

3. The HRB600E high-strength earthquake-resistant steel bar according to claim 2, characterized in that: The particle size of the precipitated phase is 2 to 4.5 nm; the number density is 1600 to 2500 nm -2 .

4. A method for preparing HRB600E high-strength earthquake-resistant steel bars according to any one of claims 1 to 3, characterized in that the steps include: S1: heating the steel billet to a first temperature at a rate of 10-20°C / s, and then holding the temperature for 120-300s to obtain a fully austenitized steel billet; the chemical composition of the steel billet is the same as that of HRB600E high-strength earthquake-resistant steel bar; S2: cooling the austenitized steel billet to a first deformation temperature, performing a first heat preservation, and rolling to obtain a first deformed steel billet; S3: cooling the first deformed steel billet to a second deformation temperature, performing a second heat preservation, and rolling to obtain a second deformed steel billet; S4: cooling the second deformed steel billet to room temperature through a third step to obtain the HRB600E high-strength earthquake-resistant steel bar; Wherein, the first temperature is 1150-1300°C.

5. The method for preparing HRB600E high-strength earthquake-resistant steel bars according to claim 4, characterized in that: The first cooling rate is 5-20°C / s, the second cooling rate is 5-20°C / s, and the third cooling rate is 0.5-20°C / s.

6. The method for preparing HRB600E high-strength earthquake-resistant steel bars according to claim 4, characterized in that: The first heat preservation time is 30 to 60 seconds, and the second heat preservation time is 30 to 60 seconds.

7. The method for preparing HRB600E high-strength earthquake-resistant steel bars according to claim 4, characterized in that: The first deformation temperature is 1000-1200°C, and the second deformation temperature is 1000-1100°C.

8. The method for preparing HRB600E high-strength earthquake-resistant steel bars according to claim 4, characterized in that: The deformation amount of the first deformed steel billet obtained after the rolling is 30%, and the deformation amount of the second deformed steel billet obtained after the rolling is 40%.

9. The method for preparing HRB600E high-strength earthquake-resistant steel bars according to claim 4, characterized in that: The deformation rates of the first deformed steel billet and the second deformed steel billet are 5 to 20 seconds respectively. -1 .

10. Use of the HRB600E high-strength earthquake-resistant steel bar according to any one of claims 1 to 3 or the HRB600E high-strength earthquake-resistant steel bar produced by the method according to any one of claims 4 to 9 in improving earthquake resistance in building structures.

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