1. A method for producing HRB500E twisted steel bars by using high-speed bars is characterized in that the method for producing the HRB500E twisted steel bars by using the high-speed bars comprises the following steps:

the method comprises the following steps of smelting blast furnace molten iron, desulfurizing and pretreating the molten iron, smelting converter molten steel, blowing argon, LF refining, continuous casting of square billets, heating by a heating furnace, rough rolling, intermediate rolling, pre-finish rolling, controlled cooling and recovery, finish rolling, controlled cooling and recovery after rolling;

the components of the HRB500E twisted steel produced by the high-speed bar are as follows: c: 0.21-0.25 Wt%, Si: 0.65-0.80 Wt%, Mn: 1.2-1.35 Wt%, P: less than or equal to 0.04 Wt%, S: less than or equal to 0.035 Wt%, V: 0.03-0.06 Wt%, Nb: 0.008-0.02 Wt%, N: 0.007-0.017 Wt%, B: 0.001-0.003 Wt%, Cr: 0.1-0.2 Wt%.

2. The method for producing HRB500E twisted steel bars with high speed bars as claimed in claim 1, wherein the HRB500E twisted steel bars with the specification of 10 to 16mm has the following composition: c: 0.21-0.25 Wt%, Si: 0.65-0.80 Wt%, Mn: 1.2-1.35 Wt%, P: less than or equal to 0.04 Wt%, S: less than or equal to 0.035 Wt%, V: 0.03-0.045 Wt%, Nb: 0.008-0.02 Wt%, N: 0.007-0.015 Wt%, B: 0.001-0.002 Wt%, Cr: 0.1-0.2 Wt%.

3. The method for producing HRB500E twisted steel bars with high speed bars as claimed in claim 1, wherein the HRB500E twisted steel bars with the specification of 18 to 25mm has the following composition: c: 0.21-0.25 Wt%, Si: 0.65-0.80 Wt%, Mn: 1.2-1.35 Wt%, P: less than or equal to 0.04 Wt%, S: less than or equal to 0.035 Wt%, V: 0.045-0.06 Wt%, Nb: 0.008-0.02 Wt%, N: 0.009-0.017 Wt%, B: 0.002-0.003 Wt%, Cr: 0.1-0.2 Wt%.

4. The method for producing HRB500E twisted steel bars with high-speed bars as claimed in claim 1, wherein the method for producing the high-speed bar steel bars with single line is as follows: the method comprises the following steps of smelting in a blast furnace molten iron, desulfurizing and pretreating the molten iron, smelting in a converter molten iron, blowing argon, LF refining, continuous casting of square billets, heating in a heating furnace, rough rolling, intermediate rolling, pre-finish rolling, single line, pre-finish rolling, controlled cooling and recovery section, finish rolling, controlled cooling and recovery section after rolling, pinch rolls, disc double-length shear, a braking device, a hub device, cooling bed cooling and fixed-length shearing.

5. The method for producing HRB500E twisted steel bars with high-speed bars as claimed in claim 1, wherein the method for producing high-speed bar steel bars with two lines is: the method comprises the following steps of smelting in a blast furnace molten iron, desulfurizing and pretreating the molten iron, smelting in a converter molten steel, blowing argon, LF refining, continuous casting of square billets, heating in a heating furnace, rough rolling, intermediate rolling, pre-finish rolling and splitting into double lines, pre-finish rolling and controlled cooling and recovery sections of the double lines, finish rolling of the double lines, double-line diameter reduction of 2 frames, controlled cooling and recovery sections after double rolling, double-line pinch rolls, double-line disc double-length shear, double-line braking devices, double-line hub devices, cooling bed cooling and fixed-length shearing.

6. The method for producing HRB500E twisted steel bars by using high-speed bars as claimed in claim 1, wherein the reducing mill set adopts 2 frames of 45-degree top-cross cantilever reducing mill, and the rolling is realized below the recrystallization temperature or in a dual-phase region by single transmission.

7. The method for producing HRB500E twisted steel bars with high speed bars as claimed in claim 1, wherein the finishing mill group is two-line using 4-stand 45 ° top cross cantilever V type non-twist super heavy duty Morgan rolling mill.

8. The method of claim 1 for producing HRB500E twisted steel from high speed rods wherein the final two frame passes are deformed by more than 15%.

9. The method for producing HRB500E twisted steel bars with high speed bars as claimed in claim 1, wherein the finish rolling speed is not less than 25m/S for HRB500E twisted steel bars with 10 to 16mm gauge.

10. The high-speed bar material is used for producing HRB500E twisted steel, and is characterized in that the components of the high-speed bar material for producing HRB500E twisted steel are as follows: c: 0.21-0.25 Wt%, Si: 0.65-0.80 Wt%, Mn: 1.2-1.35 Wt%, P: less than or equal to 0.04 Wt%, S: less than or equal to 0.035 Wt%, V: 0.03-0.06 Wt%, Nb: 0.008-0.02 Wt%, N: 0.007-0.017 Wt%, B: 0.001-0.003 Wt%, Cr: 0.1-0.2 Wt% and produced by the method for producing HRB500E twisted steel bar by using the high-speed bar material as claimed in any one of claims 1-9.

Background

The steel bar produced by the high-speed bar has good control on the overall dimension, the finish rolling speed can reach 45 m/s or above, and the steel bar has the advantages of high yield, high quality and low cost, and is the development trend of the production of the current medium and small-sized twisted steel bars. Because the high-speed bar has high deformation speed and can use the controlled rolling and controlled cooling process, the HRB400E steel bar with fine grains is produced. However, when HRB500E steel bars with higher strength are produced, the contribution of fine-grain strengthening to yield strength is large, the contribution to tensile strength is weak, and the HRB500E anti-seismic steel is difficult to meetMuscle to tendon ratio of R DEG_m/R°_eL1.25 or more.

In summary, the following problems exist in the prior art: the HRB600E twisted steel bar produced by the existing high-speed bar is difficult to satisfy the yield ratio R DEG_m/R°_eL1.25 or more.

Disclosure of Invention

The technical problem solved by the embodiment of the invention is that the HRB600E twisted steel bar produced by the existing high-speed bar is difficult to meet the yield ratio R DEG_m/R°_eLA requirement of 1.25 or more.

To this end, in one aspect, the embodiments of the present invention provide a method for producing HRB500E twisted steel from high-speed bars, where the method for producing HRB500E twisted steel from high-speed bars includes:

the method comprises the following steps of smelting blast furnace molten iron, desulfurizing and pretreating the molten iron, smelting converter molten steel, blowing argon, LF refining, continuous casting of square billets, heating by a heating furnace, rough rolling, intermediate rolling, pre-finish rolling, controlled cooling and recovery, finish rolling, controlled cooling and recovery after rolling;

the components of the HRB500E twisted steel produced by the high-speed bar are as follows: c: 0.21-0.25 Wt%, Si: 0.65-0.80 Wt%, Mn: 1.2-1.35 Wt%, P: less than or equal to 0.04 Wt%, S: less than or equal to 0.035 Wt%, V: 0.03-0.06 Wt%, Nb: 0.008-0.02 Wt%, N: 0.007-0.017 Wt%, B: 0.001-0.003 Wt%, Cr: 0.1-0.2 Wt%.

Specifically, for HRB500E twisted steel with the specification of 10-16 mm, the components are as follows: c: 0.21-0.25 Wt%, Si: 0.65-0.80 Wt%, Mn: 1.2-1.35 Wt%, P: less than or equal to 0.04 Wt%, S: less than or equal to 0.035 Wt%, V: 0.03-0.045 Wt%, Nb: 0.008-0.02 Wt%, N: 0.007-0.015 Wt%, B: 0.001-0.002 Wt%, Cr: 0.1-0.2 Wt%.

Specifically, for HRB500E twisted steel with the specification of 18-25 mm, the components are as follows: c: 0.21-0.25 Wt%, Si: 0.65-0.80 Wt%, Mn: 1.2-1.35 Wt%, P: less than or equal to 0.04 Wt%, S: less than or equal to 0.035 Wt%, V: 0.045-0.06 Wt%, Nb: 0.008-0.02 Wt%, N: 0.009-0.017 Wt%, B: 0.002-0.003 Wt%, Cr: 0.1-0.2 Wt%.

Specifically, the method for producing the high-speed bar steel bar by the single line comprises the following steps: blast furnace molten iron smelting, molten iron desulphurization pretreatment, converter molten steel smelting, argon blowing, LF refining, square billet continuous casting, heating furnace heating, rough rolling, medium rolling (6 frames), pre-finish rolling (6 frames), single line, pre-finish rolling, controlled cooling and recovery section, finish rolling (4 frames), finish rolling (2 frames of reducing diameter), controlled cooling and recovery section after rolling, pinch rolls, disc double-length shear, braking device, hub device, cooling bed cooling and fixed-length shear.

Specifically, the method for producing the high-speed bar steel bars in a double-line mode comprises the following steps: the method comprises the following steps of smelting in a blast furnace molten iron, desulfurizing and pretreating the molten iron, smelting in a converter molten steel, blowing argon, LF refining, continuous casting of square billets, heating in a heating furnace, rough rolling, intermediate rolling, pre-finish rolling and splitting into double lines, pre-finish rolling and controlled cooling and recovery sections of the double lines, finish rolling of the double lines, double-line diameter reduction of 2 frames, controlled cooling and recovery sections after double rolling, double-line pinch rolls, double-line disc double-length shear, double-line braking devices, double-line hub devices, cooling bed cooling and fixed-length shearing.

Specifically, the reducing unit adopts 2 frames of 45-degree top-cross cantilever reducing machines, and realizes rolling below the recrystallization temperature or in a dual-phase region through independent transmission.

Specifically, the finishing mill group is divided into two lines and adopts 4 frames of 45-degree top cross cantilever V-shaped non-twist ultra-heavy-load Morgan rolling mills.

Specifically, the deformation of the last two machine frame passes is more than 15%.

Specifically, for HRB500E steel bars with the specification of 10-16 mm, the finish rolling speed is not less than 25 m/S.

On the other hand, the embodiment of the invention also provides a high-speed bar material for producing HRB500E twisted steel, and the HRB500E twisted steel produced by the high-speed bar material comprises the following components: c: 0.21-0.25 Wt%, Si: 0.65-0.80 Wt%, Mn: 1.2-1.35 Wt%, P: less than or equal to 0.04 Wt%, S: less than or equal to 0.035 Wt%, V: 0.03-0.06 Wt%, Nb: 0.008-0.02 Wt%, N: 0.007-0.017 Wt%, B: 0.001-0.003 Wt%, Cr: 0.1-0.2 Wt%, and is prepared by adopting a method for producing HRB500E twisted steel bars by using high-speed bars.

Compared with the HRB500E steel bar of the conventional production line, the method for producing the HRB500E twisted steel bar by the high-speed bar has the advantages that the alloy addition is reduced, and the production cost is reduced. The qualified HRB500E steel bars can be successfully produced by a high-speed bar production line, and the production efficiency and the surface quality are high. The elements with large contribution to the tensile strength are controlled according to the upper limit, elements which can enable the CCT curve to move to the right, such as V, N, B, Cr, Nb and the like are added, and finally a small amount of bainite structures are formed in the core metallographic structure of the high-speed bar HRB500E anti-seismic steel bar, so that reasonable yield strength and high tensile strength are obtained.

Detailed Description

The present invention will now be described in order to more clearly understand the technical features, objects, and effects of the present invention.

The invention provides a method for producing HRB500E twisted steel bars by high-speed bars, which comprises the following steps:

the production process of the single-wire high-speed bar steel bar comprises the following steps: blast furnace molten iron smelting, molten iron desulphurization pretreatment, converter molten steel smelting, argon blowing, LF refining, square billet continuous casting, heating furnace heating, rough rolling (6 frames), medium rolling (6 frames), pre-finish rolling (6 frames), single line, controlled cooling and recovery section, finish rolling (4 frames), finish rolling (diameter shearing 2 frames), controlled cooling and recovery section after rolling, pinch rolls, disc double-length shear, braking device, hub device, cooling bed cooling, fixed-length shear, inspection, packaging and warehousing. Is beneficial to refining crystal grains and reducing the cost. The reinforcing steel bars are stored on each tooth of the stepping cooling bed, so that heat dissipation is accelerated, and large-size reinforcing steel bars are cooled by air on the cooling bed.

The production process of the double-line high-speed bar steel bar comprises the following steps: blast furnace molten iron smelting, molten iron desulphurization pretreatment, converter molten steel smelting, argon blowing, LF refining, square billet continuous casting, heating by a heating furnace, rough rolling (6 frames), intermediate rolling (6 frames), pre-finish rolling (6 frames) and cutting into double lines, a controlled cooling and recovery section multiplied by 2, finish rolling (4 frames) multiplied by 2, a shearing diameter 2 frames multiplied by 2, a controlled cooling and recovery section multiplied by 2 after rolling, a pinch roll multiplied by 2, a disc double-length shear multiplied by 2, a braking device multiplied by 2, a hub device multiplied by 2, cooling bed cooling, fixed-length shearing, inspecting, packaging and warehousing. Is beneficial to refining crystal grains and reducing the cost. The reinforcing steel bars are stored on each tooth of the stepping cooling bed, so that heat dissipation is accelerated, and large-size reinforcing steel bars are cooled by air on the cooling bed.

The rolling speed is kept high for different specifications.

Wherein, the process characteristics of each stage are as follows:

1. the components:

(1) c, Si: the solid solution strengthening effect is achieved, the contribution to the tensile strength is large, the contribution to the yield strength is small, and the upper limit is controlled.

(2) Mn: the solid solution strengthening effect is achieved, the contribution to the yield strength is slightly high, the cost can be reduced by controlling Mn at a moderate level, and the lost strength is compensated by fine crystalline strengthening at a lower temperature.

(3) Adding Nb to raise austenite recrystallization temperature, realizing non-recrystallization rolling at higher temperature and having precipitation strengthening effect, raising strength and increasing iron scale thickness. The trace amount of niobium dissolved in austenite delays the precipitation of pro-eutectoid ferrite and increases the time for the austenite to start decomposing and precipitating pearlite, but it hardly affects the transformation of bainite, and increases the transformation temperature of bainite, which is an advantageous element for forming bainite, so that Nb is added to control the bainite structure, and forms carbonitride to increase the strength.

(4) V, N, B content. The V element and trace B in the steel compete for N in the steel, and the combination of V and N for producing VN improves the strength of the steel and makes B difficult to combine with N to form BN. B exists on the austenite grain boundary, thereby reducing the austenite grain boundary energy and improving the stability of austenite in the temperature range above martensite, therefore, trace B can obviously improve the hardenability of steel. The elements with large contribution to the tensile strength are controlled according to the upper limit, elements which can enable the CCT curve to move to the right, such as V, N, B, Cr, Nb and the like are added, and finally a small amount of bainite structures are formed in the core metallographic structure of the high-speed bar HRB500E anti-seismic steel bar, so that reasonable yield strength and high tensile strength are obtained.

(5) Cr element. Cr has the solid solution strengthening effect, the diffusion speed of Cr in austenite is relatively low, and the diffusion of carbon can be hindered, so that the stability of austenite can be improved, the CCT curve can be shifted to the right, the critical cooling speed is reduced, the hardenability is improved, and bainite can be formed.

TABLE 1 HRB500E ingredients (wt%)

2. Arranging a rolling line:

6 rough rolling frames, 6 middle rolling frames, 6 pre-finish rolling frames, a controlled cooling device, a recovery section, 4 finishing mill sets, a controlled cooling device, a recovery section and 2 reducing mills.

6 stands of short stress line rolling mill of roughing mill group, 6 stands of short stress line rolling mill of medium rolling and 6 stands of short stress line rolling mill of pre-finish rolling (all stands are connected by loop, the bar is cut twice from the 4 th stand and enters two channels at the outlet of pre-finish rolling respectively)

The finishing mill group is two lines and adopts 4 top-crossed cantilevers (V-shaped) of 45 degrees to have no torsion and overload type Morgan rolling mills, 2 groups of modules are totally adopted, and each group of modules is driven by a motor alone, compares the collective transmission, has following advantages: each group of rollers can be independently regulated, the speed regulation range is wide, and the speed regulation flexibility is high; each motor has small power and small size; is convenient for maintenance and repair.

The reducing unit adopts 2 frames of 45-degree top-cross cantilever reducing machines for independent transmission. The addition of the reducing unit can realize rolling below the recrystallization temperature or in a dual-phase region (namely, heat engine rolling), and the aims of refining grains and improving the performance of steel are fulfilled by designing a deformation system of the last two passes to crush the grains and inducing ferrite phase change through deformation. In addition, the production rate of the rolling mill can be improved, the dimensional tolerance and the surface quality of products can be improved, the variety and the specification can be increased, the metallurgical performance of the products can be improved, and the like.

The reducing unit adopts 2 frames of 45-degree top-cross cantilever reducing machines, and realizes rolling below the recrystallization temperature or in a double-phase region through independent transmission.

The finishing mill group is a two-line V-shaped non-twist overload Morgan rolling mill with 4 frames of top cross cantilevers of 45 degrees.

And the deformation of the last two machine frame passes is more than 15%.

For HRB500E steel bar with the specification of 10-16 mm, the finish rolling speed is not less than 25 m/S.

3. The rolling process comprises the following steps:

(1) the heating time of the steel billet is 60-90 minutes, and the initial rolling temperature is as follows: 1030 +/-30 ℃.

(2) Double-line and single-line rolling with the specification of phi 10-phi 16 mm: the temperature of finish rolling and the temperature of the reducing mill are controlled, the austenite recrystallization temperature is increased by Nb, the non-recrystallization rolling of austenite can be realized at higher temperature, cooling control equipment cannot be installed behind the reducing mill, the formation of the scale is facilitated, and the temperature of the reducing mill can be slightly higher due to large deformation during single-line rolling, so that the generation of the scale is more facilitated.

(3) Double-line and single-line rolling with phi 18-phi 25 specifications: the finish rolling unit is not put into use, the water tank after pre-finish rolling and finish rolling is used by utilizing the concept of graded cooling control, the water tank is kept in a long-open state, the phenomenon that the intensity of primary cooling is overlarge and is not beneficial to the control of organization and iron scale is avoided, and the temperature of the reducer can be slightly higher due to the large deformation during single-line rolling, so that the generation of the iron scale is more beneficial. After the reducing mill is arranged to the front of the upper cooling bed, no cooling control equipment is arranged and used, so that the steel bar is in a natural cooling state, and the surface of the steel bar obtains higher temperature of the upper cooling bed.

(4) The deformation of the last two frames (K1, K2) is more than 15%.

TABLE 2 Rolling Key temperature (wt%)

4. Final rolling speed: the rolling speed is kept higher for different specifications, which is beneficial to grain refinement (see table 3).

TABLE 3 Final Rolling speed

5. Cooling by a cooling bed: the reinforcing steel bars are stored on each tooth of the stepping cooling bed, so that heat dissipation is accelerated, and large-size reinforcing steel bars are cooled by air on the cooling bed.

The measures can control the bainite content at the edge part of the cross section of the HRB500E steel bar structure to be 0%, the bainite content at 1/4 part to be 0% and the bainite content at the center part of the cross section to be 1-10%. And successfully producing qualified HRB500E steel bars by using a high-speed bar production line.

The invention also provides a high-speed bar for producing HRB500E twisted steel, and the HRB500E twisted steel produced by the high-speed bar comprises the following components: c: 0.21-0.25 Wt%, Si: 0.65-0.80 Wt%, Mn: 1.2-1.35 Wt%, P: less than or equal to 0.04 Wt%, S: less than or equal to 0.035 Wt%, V: 0.03-0.06 Wt%, Nb: 0.008-0.02 Wt%, N: 0.007-0.017 Wt%, B: 0.001-0.003 Wt%, Cr: 0.1-0.2 Wt% and produced by the method for producing HRB500E twisted steel bar by using the high-speed bar material as claimed in any one of claims 1-9.

Specifically, for HRB500E twisted steel with the specification of 10-16 mm, the components are as follows: c: 0.21-0.25 Wt%, Si: 0.65-0.80 Wt%, Mn: 1.2-1.35 Wt%, P: less than or equal to 0.04 Wt%, S: less than or equal to 0.035 Wt%, V: 0.03-0.045 Wt%, Nb: 0.008-0.02 Wt%, N: 0.007-0.015 Wt%, B: 0.001-0.002 Wt%, Cr: 0.1-0.2 Wt%.

Specifically, for HRB500E twisted steel with the specification of 18-25 mm, the components are as follows: c: 0.21-0.25 Wt%, Si: 0.65-0.80 Wt%, Mn: 1.2-1.35 Wt%, P: less than or equal to 0.04 Wt%, S: less than or equal to 0.035 Wt%, V: 0.045-0.06 Wt%, Nb: 0.008-0.02 Wt%, N: 0.009-0.017 Wt%, B: 0.002-0.003 Wt%, Cr: 0.1-0.2 Wt%.

Compared with the HRB500E steel bar of the conventional production line, the method for producing the HRB500E twisted steel bar by the high-speed bar has the advantages that the alloy addition is reduced, and the production cost is reduced. The qualified HRB500E steel bars can be successfully produced by a high-speed bar production line, and the production efficiency and the surface quality are high. The elements with large contribution to the tensile strength are controlled according to the upper limit, elements which can enable the CCT curve to move to the right, such as V, N, B, Cr, Nb and the like are added, and finally a small amount of bainite structures are formed in the core metallographic structure of the high-speed bar HRB500E anti-seismic steel bar, so that reasonable yield strength and high tensile strength are obtained.

Example (b):

1. the technology for producing phi 10-25 mm straight twisted steel bars by using double-line high-speed bars comprises the following steps: blast furnace molten iron smelting, molten iron desulphurization pretreatment, converter molten steel smelting, argon blowing, LF refining, square billet continuous casting, heating by a heating furnace, rough rolling (6 frames), intermediate rolling (6 frames), pre-finish rolling (6 frames) and cutting into double lines, a controlled cooling and recovery section multiplied by 2, finish rolling (4 frames) multiplied by 2, a shearing diameter 2 frames multiplied by 2, a controlled cooling and recovery section multiplied by 2 after rolling, a pinch roll multiplied by 2, a disc double-length shear multiplied by 2, a braking device multiplied by 2, a hub device multiplied by 2, cooling bed cooling, fixed-length shearing, inspecting, packaging and warehousing.

2. The heating time of the billet is 60-90 minutes, and the initial rolling temperature is 1010-1050 ℃.

3. The following components are mixed and prepared in a specific process. Wherein, Table 4 shows the compositions (in weight%) of the steels of the respective examples. Table 5 shows the production specifications, process parameters, mechanical properties, scale thickness corresponding to the example steels described in table 4.

Table 4: chemical composition (wt%) of product

Examples of the invention	C	Si	Mn	P	S	V	Nb	N	B	Cr
											Example 1	0.23	0.70	1.25	0.035	0.027	0.035	0.012	0.0126	0.0015	0.14
Example 2	0.24	0.75	1.22	0.029	0.025	0.041	0.015	0.0121	0.0017	0.16
											Example 3	0.22	0.72	1.26	0.031	0.033	0.037	0.016	0.0135	0.0014	0.15
Example 4	0.24	0.69	1.28	0.026	0.032	0.055	0.014	0.0159	0.0026	0.12
											Example 5	0.25	0.71	1.23	0.033	0.029	0.052	0.013	0.0142	0.0023	0.18

Table 5: specific process parameters and mechanical properties of the examples

The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. In order that the components of the present invention may be combined without conflict, it is intended that all equivalent changes and modifications made by those skilled in the art without departing from the spirit and principles of the present invention shall fall within the protection scope of the present invention.