CN116200665A

CN116200665A - HRB500E anti-seismic reinforcing steel bar and preparation method thereof

Info

Publication number: CN116200665A
Application number: CN202310165436.5A
Authority: CN
Inventors: 周玉丽; 宫翠; 邸全康; 王晓晨; 晁月林; 周洁; 李舒笳; 刘洋洋; 王勇; 代锦; 周剑波; 侯栋; 徐兵伟; 丁建国; 吴明安; 宋健; 张鑫; 李宁; 胡洪; 赵攀峰
Original assignee: Shougang Group Co Ltd
Current assignee: Shougang Group Co Ltd
Priority date: 2023-02-24
Filing date: 2023-02-24
Publication date: 2023-06-02

Abstract

The application relates to an HRB500E anti-seismic steel bar and a preparation method thereof, and belongs to the technical field of anti-seismic steel bar production. The chemical components of the steel bar comprise: c:0.20 wt% to 0.25 wt%, si:0.50 wt% to 0.75 wt%, mn:1.20 wt% to 1.40 wt%, P: less than or equal to 0.030 weight percent, S: less than or equal to 0.030 weight percent, V:0.05 wt% to 0.08 wt%, fe; the metallographic structure of the steel bar is as follows: ferrite and pearlite. The preparation method of the HRB500E anti-seismic steel bar provided by the application cancels a heating link of a heating furnace, optimizes the composition control, continuous casting billet pulling speed control, direct rolling heat preservation roller way conveying control, start rolling temperature, finish rolling inlet temperature, spinning temperature, air cooling process, roller way speed and the like, and has excellent tissue performance, mechanical performance and anti-seismic performance of the produced HRB500E anti-seismic steel bar, wherein the performance parameter Rp0.2 is more than or equal to 520Mpa, the tensile strength Rm is more than or equal to 700Mpa, the elongation is more than or equal to 18%, agt is more than or equal to 9%, the strength-to-deflection ratio is more than or equal to 1.25, and the Qu Qu ratio is less than or equal to 1.2.

Description

HRB500E anti-seismic reinforcing steel bar and preparation method thereof

Technical Field

The application relates to the field of anti-seismic steel bars, in particular to an HRB500E anti-seismic steel bar and a preparation method thereof.

Background

With the development of the heating-free direct rolling production technology, the application degree of continuous casting billet hot charging and hot feeding and continuous casting direct rolling technology has become a new index for measuring the steel production technology level.

At present, the HRB500E steel bar prepared by the heating-free direct rolling production technology can not only have the phenomenon of insufficient plastic toughness of products, but also have the phenomenon of large fluctuation of product performance, so that part of products cannot meet the anti-seismic requirement.

Disclosure of Invention

The application provides an HRB500E anti-seismic steel bar and a preparation method thereof, which are used for solving the technical problems of insufficient plastic toughness and large fluctuation of product yield strength of the existing HRB500E anti-seismic steel bar prepared by a heating-free direct rolling production technology.

In a first aspect, the present application provides an HRB500E earthquake-resistant rebar, the rebar comprising the chemical constituents:

c:0.20 wt% to 0.25 wt%, si:0.50 wt% to 0.75 wt%, mn:1.20 wt% to 1.40 wt%, P: less than or equal to 0.030 weight percent, S: less than or equal to 0.030 weight percent, V:0.05 wt% to 0.08 wt% of Fe.

Optionally, the metallographic structure of the steel bar is: ferrite and pearlite.

Optionally, the ferrite is present in an amount of 35% to 55% by volume.

Alternatively, the average diameter of the ferrite grains is 9.5 μm to 10 μm.

Optionally, the pearlite is present in an amount of 45% to 65% by volume.

Alternatively, the average diameter of the grains of the pearlite is 20 μm to 50 μm.

In a second aspect, the present application provides a method for preparing an HRB500E earthquake-resistant steel bar, for preparing the HRB500E earthquake-resistant steel bar according to any one of the first aspects, the method comprising:

continuously casting the molten steel containing the chemical components under the condition of setting the drawing speed to obtain a casting blank;

under the condition of setting the initial rolling temperature, carrying out heat preservation and conveying of the casting blank to a rolling mill for rough rolling;

performing finish rolling on the rough rolled casting blank under the condition of setting the finish rolling temperature to obtain strip steel;

carrying out spinning treatment on the strip steel under the condition of setting spinning temperature to obtain a reinforcing steel bar;

and (3) air cooling the steel bars under the conditions of setting the first section roller way speed, setting the final cooling temperature and setting the joint temperature.

Optionally, the value of the set blank pulling speed is not less than 3.0m/min; and/or

The value of the set initial rolling temperature is 950-980 ℃.

Optionally, the value of the set finish rolling temperature is 860-880 ℃; and/or

The value of the set spinning temperature is 910-930 ℃.

Optionally, the value of the speed of the roller way at the first section is set to be 0.6m/s-0.7m/s, the value of the final cooling temperature is set to be 660-680 ℃, and the value of the temperature of the set overlap point is not more than 680 ℃.

Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:

according to the method provided by the embodiment of the application, a heating link of a heating furnace is omitted, optimization is performed in terms of chemical composition design, the strength, hardness and hardenability of steel are improved by adding a proper amount of Mn element, the hot processing performance of the steel is improved, the strength and the strength-to-deflection ratio of the material are improved by adding a proper amount of C element, the elastic limit, the yield point and the tensile strength of the steel are improved by adding a proper amount of Si element, and the structure grains are refined by adding a proper amount of V element, so that the strength and the toughness are improved; the HRB500E anti-seismic steel bar produced by the design components has the characteristics of excellent plastic toughness and product yield strength fluctuation less than 50 MPa.

Drawings

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

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the description of the embodiments or the prior art will be briefly described below, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without inventive effort.

Fig. 1 is a schematic flow chart of a method for preparing an HRB500E earthquake-resistant steel bar according to an embodiment of the present application;

Detailed Description

For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.

Unless specifically indicated otherwise, the various raw materials, reagents, instruments, equipment, and the like used in this application are commercially available or may be prepared by existing methods.

Various embodiments of the present application may exist in a range format; it should be understood that the description in a range format is merely for convenience and brevity and should not be interpreted as a rigid limitation on the scope of the application. It is therefore to be understood that the range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that a description of a range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, wherever applicable. In addition, whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the indicated range.

In this application, unless otherwise indicated, terms of orientation such as "upper" and "lower" are used specifically to refer to the orientation of the drawing in the figures. In addition, in the description of the present application, the terms "include", "comprising" and the like mean "including but not limited to".

Relational terms such as "first" and "second", and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Herein, "and/or" describing an association relationship of an association object means that there may be three relationships, for example, a and/or B, may mean: a alone, a and B together, and B alone. Wherein A, B may be singular or plural. Herein, "at least one" means one or more, and "a plurality" means two or more. "at least one", "at least one" or the like refer to any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a. b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.

In the embodiment, the effect of C is to improve the strength and the strong buckling ratio of the material, but the plasticity and the impact toughness are reduced, the reason for controlling the mass fraction of C to be 0.20% -0.25% is to obtain proper strength and the strong buckling ratio, the adverse effect of the excessive mass fraction is that the standard requirement is not met, and the adverse effect of the excessive mass fraction is that the strength and the strong buckling ratio are insufficient;

in this example, si functions to increase the elastic limit, yield point and tensile strength of steel, but reduces the weldability of steel. The reason for controlling the mass fraction of Si to be 0.50% -0.75% is to obtain a proper yield point and ensure welding performance, wherein the adverse effect of the excessive mass fraction is that the welding performance is reduced, and the adverse effect of the insufficient mass fraction is that the strength is insufficient;

in this example, mn has an effect of increasing the strength, hardness and hardenability of steel, improving the hot workability of steel, but weakening the corrosion resistance of steel and reducing the weldability. The reason for controlling the mass fraction of Mn to be 1.20% -1.40% is to obtain proper strength hardness and welding performance, and the adverse effect of the mass fraction with excessive value is poor welding performance and the adverse effect of the mass fraction with insufficient strength hardness;

in general, P, S is a harmful element in steel, and P increases cold brittleness of steel, deteriorates welding performance, reduces plasticity, and deteriorates cold bending performance. S causes hot shortness of the steel, and reduces the ductility and toughness of the steel. The lower P, S in the steel the better, but the lower the requirement increases the investment in equipment and costs.

V has the function of refining the structure grains and improving the strength and the toughness. The carbon-nitrogen compound formed by vanadium, carbon and nitrogen can improve the hydrogen corrosion resistance under high temperature and high pressure. The reason for controlling the mass fraction of V to be 0.05-0.08% is to obtain proper grain size and strength, and the adverse effect of the excessive mass fraction is that the strength is too high, the strength-to-yield ratio is insufficient, and the adverse effect of the too small is that the strength is insufficient;

in some embodiments, the steel bar has a metallographic structure of: ferrite and pearlite.

The advantage of the structure being ferrite and pearlite is that a good match of strength and plasticity can be obtained.

In some embodiments, the ferrite is present in an amount of 35% to 55% by volume.

The advantage of controlling the structure to be 35-55% ferrite by volume is that good plasticity is obtained.

In some embodiments, the average diameter of the ferrite grains is 9.5 μm to 10 μm.

The advantage of ferrite grains having an average diameter of 9.5 μm to 10 μm is that a suitable strength and strength to yield ratio is obtained.

In some embodiments, the pearlite is present in an amount of 45% to 65% by volume.

The advantage of a pearlite content of 45-65% by volume is that a suitable strength is obtained.

In some embodiments, the average diameter of the grains of pearlite is 20 μm to 50 μm.

The advantage of the average diameter of the grains of pearlite being 20 μm to 50 μm is that a good strength and plasticity match is obtained.

In this embodiment, the HRB500E earthquake-resistant steel bar is produced by the following process: molten iron, converter smelting, alloy adding, LF refining, continuous casting into small square billets, straight roller channel conveying, controlled rolling and controlled cooling, wherein the alloy is added at the end point of the converter, the continuous casting adopts full protection casting, and the superheat degree is not more than 35 ℃. The heat preservation is conveyed to a rolling mill: the high-pulling-speed continuous casting billet from the casting machine is subjected to heat preservation between the withdrawal and straightening machine and the hydraulic shear, heat preservation between the hydraulic shear and the fixed length, heat preservation on a waiting position of a conveying roller way, an automatic steel-making system is arranged, the continuous casting billet passes through a converging climbing turning heat preservation roller way and a direct rolling heat preservation roller way of a steel rolling area according to the time interval of high-speed line or high-rod steel rolling, and is converged into a discharging roller way from the side of a heating furnace, and is sent into a rolling mill for direct rolling, so that the tail temperature in the head of the continuous casting billet is uniform when the continuous casting billet enters the rolling mill, and the temperature difference is controlled within 30 ℃. In the air cooling stage, fans 1# and 2# are started according to 100%, and the fan 3# is started by 80%.

In some embodiments, the set withdrawal speed has a value of not less than 3.0m/min; and/or

The value of the set initial rolling temperature is 950-980 ℃.

When the pulling speed is lower than 3.0m/min, the difference between the temperature of the head part of the casting blank and the temperature of the tail part of the casting blank is too large, so that the setting requirement of the initial rolling temperature is not met, and the setting of the initial rolling temperature to 950-980 ℃ has the advantages of refining austenite grains and avoiding overload of initial rolling equipment.

In some embodiments, the set finish rolling temperature has a value of 860 ℃ to 880 ℃; and/or

The value of the set spinning temperature is 910-930 ℃.

The advantages of finishing temperature of 860-880 ℃ and spinning temperature of 910-930 ℃ are that austenite grains are refined and overload of finishing equipment is avoided.

In some embodiments, the set first stage roller speed is 0.6m/s to 0.7m/s, the set final cooling temperature is 660 ℃ to 680 ℃, and the set overlap point temperature is no greater than 680 ℃.

The first section roller way speed is controlled to be 0.6-0.7 m/s, and the advantages of the method are that overlap joint is reduced, and cooling is uniform.

The temperature of the lap joint is controlled to be not higher than 680 ℃, and the advantage of the lap joint is that the phase change of the lap joint is ensured to be completed.

The present application is further illustrated below in conjunction with specific examples. It should be understood that these examples are illustrative only of the present application and are not intended to limit the scope of the present application. The experimental procedures, which are not specified in the following examples, are generally determined according to national standards. If the corresponding national standard does not exist, the method is carried out according to the general international standard, the conventional condition or the condition recommended by the manufacturer.

Example 1:

the chemical components used in this example are: c:0.25 wt%, si:0.75 wt%, mn:1.40 wt%, V:0.08 wt.%, the balance being Fe and unavoidable impurities. The production process of the HRB500E anti-seismic steel bar is shown in figure 1, wherein alloy is added at the end point of a converter, full protection casting is adopted for continuous casting, the superheat degree is not more than 35 ℃, and the heat preservation conveying control is as follows: the continuous casting billet with high pulling speed from the casting machine is subjected to heat preservation between the withdrawal and straightening machine and the hydraulic shear, heat preservation between the hydraulic shear and the fixed length, heat preservation on the waiting position of a conveying roller way, an automatic steel-making system is arranged, and the continuous casting billet passes through a converging climbing turning heat preservation roller way and a direct rolling heat preservation roller way of a steel rolling area according to the time interval of high-speed line or high-rod steel rolling, is gathered into a discharging roller way from the side of a heating furnace, and is sent into the rolling machine for direct rolling. The initial rolling temperature is 978 ℃, the finish rolling temperature is 878 ℃, the spinning temperature is 928 ℃, and the air cooling process is as follows: the fans 1# and 2# are started according to 100%, the fan 3# is started to 80%, the speed of a first section roller way is 0.65m/s, the final cooling temperature is controlled to 675 ℃, the maximum temperature of a lap joint is 675 ℃, and the mechanical properties are shown in the table 1.

Example 2:

the chemical components used in this example are: c:0.23 wt%, si:0.62 wt%, mn:1.30 wt%, V:0.065 wt%, the balance being Fe and unavoidable impurities. The production process of the HRB500E anti-seismic steel bar is shown in figure 1, wherein alloy is added at the end point of a converter, full protection casting is adopted for continuous casting, the superheat degree is not more than 35 ℃, and the heat preservation conveying control is as follows: the continuous casting billet with high pulling speed from the casting machine is subjected to heat preservation between the withdrawal and straightening machine and the hydraulic shear, heat preservation between the hydraulic shear and the fixed length, heat preservation on the waiting position of a conveying roller way, an automatic steel-making system is arranged, and the continuous casting billet passes through a converging climbing turning heat preservation roller way and a direct rolling heat preservation roller way of a steel rolling area according to the time interval of high-speed line or high-rod steel rolling, is gathered into a discharging roller way from the side of a heating furnace, and is sent into the rolling machine for direct rolling. The initial rolling temperature is 966 ℃, the finish rolling temperature is 871 ℃, the spinning temperature is 921 ℃, and the air cooling process is as follows: the fans 1# and 2# are started according to 100%, the fan 3# is started to 80%, the speed of a first section roller way is 0.65m/s, the final cooling temperature is controlled to 670 ℃, the maximum temperature of a lap joint is 671 ℃, and the mechanical properties are shown in table 1.

Example 3:

the chemical components used in this example are: c:0.20 wt%, si:0.50 wt%, mn:1.20 wt%, V:0.05 wt.%, balance Fe and unavoidable impurities. The production process of the HRB500E anti-seismic steel bar is shown in figure 1, wherein alloy is added at the end point of a converter, full protection casting is adopted for continuous casting, the superheat degree is not more than 35 ℃, and the heat preservation conveying control is as follows: the continuous casting billet with high pulling speed from the casting machine is subjected to heat preservation between the withdrawal and straightening machine and the hydraulic shear, heat preservation between the hydraulic shear and the fixed length, heat preservation on the waiting position of a conveying roller way, an automatic steel-making system is arranged, and the continuous casting billet passes through a converging climbing turning heat preservation roller way and a direct rolling heat preservation roller way of a steel rolling area according to the time interval of high-speed line or high-rod steel rolling, is gathered into a discharging roller way from the side of a heating furnace, and is sent into the rolling machine for direct rolling. The initial rolling temperature is 955 ℃, the finish rolling temperature is 861 ℃, the spinning temperature is 912 ℃, and the air cooling process is as follows: the fans 1# and 2# are started according to 100%, the fan 3# is started to 80%, the speed of a first section roller way is 0.65m/s, the final cooling temperature is controlled to 662 ℃, the maximum temperature of the lap joint is 665 ℃, and the mechanical properties are shown in table 1.

The related experiment test method comprises the following steps:

the metallographic structure detection method comprises the following steps: GB/T13298, method for metal microstructure inspection.

The mechanical property detection method comprises the following steps: GB/T18900 steel test method for reinforced concrete.

Related experiment and effect data:

TABLE 1

Steel grade	R _el ,MPA	Rm,MPa	A5％	Agt,％	Rm/R _el	R ^o _el /R _el
							Example 1	585	780	24.0	13.5	1.33	1.17
Example 2	575	760	25.0	13.0	1.32	1.15
							Example 3	535	720	25.5	13.0	1.35	1.07

The invention reasonably designs the processes of chemical components, continuous casting drawing speed, heat preservation conveying roller way, rolling, air cooling and the like, so that the temperature of the head, middle and tail parts of a continuous casting blank of the heating-free HRB500E anti-vibration steel bar is uniform when the continuous casting blank enters a rolling mill, the temperature difference is controlled within 30 ℃, the starting rolling temperature can meet the conventional process requirement, the fluctuation of the yield strength of the product is within 50MPa, the narrow-range stable control of the comprehensive performance is realized, the purpose of energy saving and consumption reduction is also achieved, and the high-strength anti-vibration steel bar produced by the invention has the structure of ferrite and pearlite, the ferrite grain size is 9.5-10.5 grade, rp0.2 is more than or equal to 520MPa, the tensile strength Rm is more than or equal to 700MPa, the elongation is more than or equal to 18%, the Agt is more than or equal to 9%, the strength-to 1.25, and the Qu Qu ratio is less than or equal to 1.2.

The foregoing is merely a specific embodiment of the application to enable one skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An HRB500E earthquake-resistant rebar, wherein the rebar comprises the following chemical components:

2. The HRB500E earthquake-resistant rebar of claim 1, wherein the rebar has a metallographic structure of: ferrite and pearlite.

3. The HRB500E earthquake-resistant steel bar of claim 1 or 2, wherein the ferrite content is 35-55% by volume.

4. HRB500E earthquake-resistant steel according to claim 1 or 2, wherein the average diameter of the ferrite grains is 9.5-10 μm.

5. The HRB500E earthquake-resistant steel bar of claim 1 or 2, wherein the pearlite content is 45-65% by volume.

6. HRB500E earthquake-resistant steel according to claim 1 or 2, wherein the average diameter of the grains of pearlite is 20-50 μm.

7. A method for preparing an HRB500E earthquake-resistant steel bar, the method comprising:

and (3) air cooling the steel bars under the conditions of setting the first section roller way speed, setting the final cooling temperature and setting the lap joint temperature.

8. The method according to claim 7, wherein the set withdrawal speed has a value of not less than 3.0m/min; and/or

The value of the set initial rolling temperature is 950-980 ℃.

9. The method according to claim 7, wherein the set finish rolling temperature has a value of 860 ℃ to 880 ℃; and/or

The value of the set spinning temperature is 910-930 ℃.

10. The method according to claim 7, wherein the set first stage roller speed is 0.6m/s to 0.7m/s, the set final cooling temperature is 660 ℃ to 680 ℃, and the set overlap point temperature is not more than 680 ℃.