阅读说明：本技术 一种经济型630MPa高强抗震钢筋用钢及其生产方法 (Economical 630MPa high-strength anti-seismic steel bar steel and production method thereof ) 是由 于同仁 汪开忠 郭湛 余良其 杨应东 张晓瑞 姜婷 宋祖峰 袁月 尹德福 龚梦强 于 2021-06-18 设计创作，主要内容包括：本发明的一种经济型630MPa高强抗震钢筋用钢及其生产方法,属于混凝土用热轧带肋钢筋技术领域。经济型630MPa高强抗震钢筋用钢其化学成分组成及重量百分比含量包括：C：0.20～0.30％,Si：0.40～0.80％,Mn：1.40～1.60％,P：≤0.035％,S：≤0.035％,Nb：0.010～0.020％,V：0.050～0.100％,N：0.008～0.015％,W：0.010～0.020％,其余为Fe和不可避免的杂质元素。除C、Si、Mn、V、Nb等常规强化元素外,通过少量添加W元素,利用其在钢中形成稳定的W-2(C、N)、W(C、N)的高硬度碳氮化物,提高钢的强度。(The invention discloses an economical steel for 630MPa high-strength anti-seismic reinforcing steel bars and a production method thereof, and belongs to the technical field of hot-rolled ribbed reinforcing steel bars for concrete. The economical 630MPa high-strength anti-seismic steel bar comprises the following chemical components in percentage by weight: c: 0.20 to 0.30%, Si: 0.40-0.80%, Mn: 1.40-1.60%, P: less than or equal to 0.035%, S: less than or equal to 0.035%, Nb: 0.010-0.020%, V: 0.050 to 0.100%, N: 0.008-0.015%, W: 0.010-0.020%, and the balance of Fe and inevitable impurity elements. Besides the conventional strengthening elements such as C, Si, Mn, V, Nb and the like, by adding a small amount of W element,by means of which stable W is formed in steel 2 (C, N) and W (C, N) to improve the strength of the steel.)

1. The economical 630MPa high-strength anti-seismic steel bar steel is characterized by comprising the following chemical components in percentage by weight: c: 0.20 to 0.30%, Si: 0.40-0.80%, Mn: 1.40-1.60%, P: less than or equal to 0.035%, S: less than or equal to 0.035%, Nb: 0.010-0.020%, V: 0.050 to 0.100%, N: 0.008-0.015%, W: 0.010-0.020%, and the balance of Fe and inevitable impurity elements.

2. The economical 630MPa high-strength anti-seismic steel bar according to claim 1, wherein the chemical composition comprises: 1.35[ C ] +0.8[ N ] not more than 0.5[ W ] +0.2[ V ] +0.3[ Nb ] +0.25[ Si ] +0.1[ Mn ].

3. The economical 630MPa high-strength anti-seismic steel bar according to claim 1, wherein the chemical composition comprises: mo is more than or equal to 0.1 and less than or equal to 0.3.

4. The economical 630MPa high-strength anti-seismic steel bar steel according to claim 1, wherein the metallographic structure of the economical 630MPa high-strength anti-seismic steel bar steel is as follows: ferrite + pearlite.

5. The production method of the economical 630MPa high-strength anti-seismic steel bar is characterized by comprising the following steps of:

s1, smelting molten steel, and adding ferrotungsten in the tapping process of the smelting furnace;

s2, refining in an LF furnace;

s3, continuous casting;

s4, rolling an austenite non-recrystallization region;

and S5, quickly cooling after rolling, and putting on a cooling bed.

6. The method for producing an economical 630MPa high-strength aseismic steel bar according to claim 5, wherein in the step S1, ferrotungsten is added when the smelting furnace taps 3/5.

7. The production method of the economical 630MPa high-strength anti-seismic steel bar according to claim 5, wherein in the step S2, the refining time of the LF furnace is not less than 20 min.

8. The method for producing an economical 630MPa high-strength aseismic reinforcing steel bar according to claim 5, wherein the step S4 of rolling the austenite non-recrystallized zone comprises the steps of:

(1) the heating temperature range is as follows: 1080-1180 ℃; the soaking temperature range is as follows: 1030-1130 ℃, the soaking time range is as follows: 80-120 min;

(2) the initial rolling temperature range is as follows: 950-1050 ℃;

(3) the finishing mill temperature range is: 900 to 950 ℃.

9. The method for producing economical 630MPa high-strength aseismic reinforcing steel bar according to claim 5, wherein a water spray cooling device is provided before finish rolling in step S4.

10. The method for producing the economical 630MPa high-strength anti-seismic steel bar according to claim 5, wherein in the step S5, the upper cooling bed red-returning temperature range is as follows: 800-900 ℃.

Technical Field

The invention belongs to the technical field of hot-rolled ribbed steel bars for concrete, and particularly relates to economical steel for 630MPa high-strength anti-seismic steel bars and a production method thereof.

Background

The high-speed industrialization and urbanization of China drive the rapid development of the construction industry, and the construction steel bars become the varieties with the largest consumption in steel products, and account for 1/5 of the total steel yield. In recent years, along with the popularization and application of a series of policies for reinforcing the high-strength steel bars, the yield and the growth rate of the high-strength steel bars and the proportion of the yield of the high-strength steel bars to the annual yield of the steel bars in China are in the situation of increasing year by year.

By applying the high-strength reinforcing steel bars, the workload of logistics transportation, processing and connection of the construction reinforcing steel bars can be reduced in the engineering construction stage, so that the consumption of energy and resources such as land, coal, water, ore and the like is saved, and the consumption of CO (carbon monoxide) is reduced₂、SO₂And the emission of harmful gases and waste residues; in the use stage, the energy consumption of building heating, illumination, household appliances, ventilation and the like can be reduced, the maintenance and use cost is reduced, the engineering cost is reduced, and huge direct or indirect economic benefits are obtained. High-strength steel barThe popularization and the application of the method accord with the national policy of sustainable development proposed by China, the energy and fuel can be saved and reasonably utilized, the scientific development of engineering construction can be promoted, and the method has important significance for promoting the structure adjustment, transformation and upgrading of the steel industry, eliminating the backward productivity and implementing the sustainable development.

Chinese patent application No. 201310444163.4, published as: 2014-01-08 discloses 'a 630 MPa-grade high-strength hot-rolled steel bar and a production process thereof'. The twisted steel comprises the following components: 0.38-0.43% of C, 0.8-1.1% of Cr, 0.75-1.0% of Mn, 0.15-0.25% of Mo, 0.15-0.3% of Si, less than or equal to 0.035% of S, P, less than or equal to 0.035% of N, and the balance of Fe. The manufacturing method of the twisted steel bar adopts a heating furnace to heat to 1000-1200 ℃, then cools the steel bar to 610-630 ℃ rapidly through an online first cooling procedure, then quenches the steel bar by water or quenching liquid in a quenching device within 12-14 seconds, then heats the steel bar to 550-660 ℃ through a tempering heating furnace, and then cools the steel bar to normal temperature through a second cooling procedure. It has the following disadvantages: (1) the Cr and Mo contents are high, the production cost is greatly increased, and the Cr is not favorable for extending indexes and is easy to break; (2) c, N content is too high to facilitate welding performance; (3) most of domestic steel bar production lines do not have an online tempering device, and the production process is difficult to realize.

Chinese patent application No. 201310593620.6, published as: 2014-03-19 discloses "a reinforced bar with high strength above 630MPa and a reinforced concrete application method thereof". The high-strength steel bar comprises the following components in percentage by weight: 0.28 to 0.38 percent of carbon, 0 to 0.35 percent of silicon, 0 to 0.90 percent of manganese, 0.80 to 1.50 percent of chromium, 3.00 to 4.00 percent of nickel, 0.40 to 0.60 percent of molybdenum, 0 to 0.015 percent of phosphorus, 0 to 0.015 percent of sulfur, 0 to 2.0ppm of hydrogen, 0.10 to 0.20 percent of vanadium, 0 to 0.025 percent of titanium, 0 to 0.20 percent of copper, 0 to 0.05 percent of aluminum, 0 to 0.50 percent of residual elements and the balance of Fe. The high-strength steel bar contains a large amount of alloys such as Ni and Mo which are national strategic resources, so that the production cost is high, and unnecessary waste of the national strategic resources is caused.

Based on the above, the invention provides the economical steel for the 630MPa high-strength anti-seismic reinforcing steel bar and the production method thereof by combining the existing process and related equipment, and greatly saves the cost and resources on the premise of meeting the performance requirement of the 630MPa high-strength reinforcing steel bar.

Disclosure of Invention

1. Problems to be solved

Aiming at the problems of poor anti-seismic performance and low strength of the existing steel bar, the invention provides an economical 630MPa high-strength anti-seismic steel bar steel; the component range of the 635MPa steel bar and the two-phase region rolling process are designed by combining the existing process equipment conditions, and the strength grade reaches 635MPa on the premise of not reducing the ductility index, so that the requirements of high-rise and large-span building structures are met.

The invention also aims to provide a production method of the economical 630MPa high-strength anti-seismic steel bar.

2. Technical scheme

In order to solve the problems, the technical scheme adopted by the invention is as follows:

the invention relates to an economical 630MPa high-strength anti-seismic steel bar steel, which comprises the following chemical components in percentage by weight: c: 0.20 to 0.30%, Si: 0.40-0.80%, Mn: 1.40-1.60%, P: less than or equal to 0.035%, S: less than or equal to 0.035%, Nb: 0.010-0.020%, V: 0.050 to 0.100%, N: 0.008-0.015%, W: 0.010-0.020%, and the balance of Fe and inevitable impurity elements. In addition to the conventional strengthening elements such as C, Si, Mn, V, Nb, etc., the W element is added in a small amount, and is utilized to form stable W in steel₂(C, N) and W (C, N) to improve the strength of the steel.

As a further illustration of the present invention, the chemical composition is as follows: 1.35[ C ]]+0.8[N]≤0.5[W]+0.2[V]+0.3[Nb]+0.25[Si]+0.1[Mn]。W₂(C, N) and W (C, N) can play a role in inhibiting grain growth, ensure the ductility of steel, namely, by utilizing the formula, enough carbonitride precipitation is ensured, the precipitation strengthening effect of V, Nb and Mo is fully exerted, and the strength requirement is met.

As a further illustration of the present invention, the chemical composition is as follows: mo is more than or equal to 0.1 and less than or equal to 0.3. By adopting the rolling process of the austenite non-recrystallization region, the growth of crystal grains is inhibited, and simultaneously a large amount of dislocation and sub-crystal are promoted to be formed in the crystal grains, on the premise of ensuring the performance, the addition amount of microalloy elements such as V, Nb is greatly reduced, a small amount of W element is added to make up the strength reduction caused by the reduction of V and Nb, namely the formula ensures that the rolling of the austenite non-recrystallization region is realized under the condition of ensuring the proper proportion of W and V, Nb elements.

As further illustration of the invention, the metallographic structure of the economical 630MPa high-strength anti-seismic steel bar is as follows: ferrite + pearlite.

The invention relates to a production method of an economical 630MPa high-strength anti-seismic steel bar, which comprises the following steps:

s1, smelting molten steel, and adding ferrotungsten in the tapping process of the smelting furnace;

s2, refining in an LF furnace;

s3, continuous casting;

s4, rolling an austenite non-recrystallization region;

and S5, quickly cooling after rolling, and putting on a cooling bed.

As a further explanation of the present invention, it is characterized in that ferrotungsten is added when the steel 3/5 is tapped from the smelting furnace in step S1.

As a further description of the invention, the refining time of the LF furnace in the step S2 is not less than 20 min.

As a further explanation of the present invention, the step S4 is characterized in that the rolling of the austenite non-recrystallized region includes the steps of:

(1) the heating temperature range is as follows: 1080-1180 ℃; the soaking temperature range is as follows: 1030-1130 ℃, the soaking time range is as follows: 80-120 min; the method is favorable for austenitizing the steel and promoting the dissolution of Si, Mn, V, Nb and W in austenite, and the square billet is cooled by water spray on a conveying roller way.

(2) The initial rolling temperature range is as follows: 950-1050 ℃; rolling by 6 frames of rough rolling mill set with 20% of deformation, rolling by 6 frames of middle rolling mill set with 20% of deformation, and arranging a water spray cooling device between the middle rolling mill set and the finishing mill set.

(3) The finishing mill temperature range is: 900-950 ℃; the steel is rolled in an austenite non-recrystallization region by a 6-frame finishing mill group, the large deformation amount is 60 percent, the transformation from gamma austenite to alpha ferrite + P pearlite is promoted by utilizing the low temperature and the large deformation amount, ferrite grains are refined, a large amount of dislocation is promoted to be formed in the grains, and the toughness of the steel is improved.

As a further feature of the present invention, in step S4, a water spray cooling device is provided before finish rolling.

As a further description of the present invention, in step S5, the upper cooling bed temperature range of returning red is: 800-900 ℃. And a rapid water cooling device is arranged behind the finishing mill, the temperature of red returning on the cooling bed is controlled to be 800-900 ℃ after the finish rolling, an ideal fine grain structure mainly comprising ferrite and pearlite is obtained, the grain size reaches 9 grades and above, and the precipitation of second phase particles of V (C, N) and NbC is promoted, so that the toughness of the steel bar is improved.

3. Advantageous effects

Compared with the prior art, the invention has the beneficial effects that:

(1) the economical 630MPa high-strength anti-seismic steel bar provided by the invention has the advantages that the produced steel has the yield strength of more than or equal to 630MPa, the tensile strength of more than or equal to 790MPa, the elongation after fracture of more than or equal to 15%, the total elongation under maximum force of more than or equal to 9.0%, the yield ratio of more than or equal to 1.25 and the yield ratio of less than or equal to 1.30. The key technology to be solved is to provide an economic alloy component range and an austenite non-recrystallization rolling process of the 630MPa grade high-strength anti-seismic steel bar, so that the requirement of the market on the 630MPa grade high-strength anti-seismic steel bar is met, and the cost and the resource are greatly saved;

(2) according to the economical 630MPa high-strength anti-seismic steel bar, the economical component design is adopted, the rolling method of the austenite non-recrystallization region is combined, the comprehensive strengthening measures such as solid solution and precipitation of micro-alloy elements and rolling fine grain strengthening of the austenite non-recrystallization region are comprehensively utilized, the strength and toughness of the steel bar are improved, and the performance requirement of the 630MPa high-strength anti-seismic steel bar is met;

(3) the invention relates to a production method of an economical 630MPa high-strength anti-seismic steel bar, which is characterized in that the heating temperature is controlled to be 1080-1180 ℃, the soaking temperature is controlled to be 1030-1130 ℃, the soaking time is 80-120min, the austenitization of the steel and the promotion of the dissolution of Si, Mn, V, Nb and W in austenite are facilitated, a square billet is cooled on a conveying roller way by water spray, the initial rolling temperature is controlled to be 950-1050 ℃, the square billet is rolled by 6 roughing mill sets, the deformation amount is 20 percent, the square billet is rolled by 6 middle mill sets, the deformation amount is 20 percent, a water spray cooling device is arranged between the middle mill sets and the finishing mill sets, the temperature of a finishing mill is controlled to be 900-950 ℃, the square billet is rolled in an austenite non-recrystallization region by 6 finishing mill sets, the large deformation amount is 60 percent, the transformation of gamma austenite to alpha ferrite plus P pearlite is promoted by utilizing the low temperature and the large deformation amount, the transformation of the gamma austenite is promoted, ferrite grains are refined, the dislocation is promoted, the strength and toughness of the steel are improved, a rapid water cooling device is arranged behind a finishing mill, the temperature of red returning of an upper cooling bed is controlled to be 800-900 ℃ after rolling, an ideal fine grain structure mainly comprising ferrite and pearlite is obtained, the grain size reaches 9 grades and above, and the precipitation of second phase particles of V (C, N) and NbC is promoted, so that the strength and toughness of the steel bar are improved.

Drawings

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and examples, but it should be understood that these drawings are designed for illustrative purposes only and thus do not limit the scope of the present invention. Furthermore, unless otherwise indicated, the drawings are intended to be illustrative of the structural configurations described herein and are not necessarily drawn to scale.

Fig. 1 is a schematic diagram of 500 times metallographic structure of an economical 630MPa high-strength anti-seismic reinforcing steel bar of the invention, wherein white: ferrite, gray: pearlite, grade 11.5 grain size.

Detailed Description

The following detailed description of exemplary embodiments of the invention refers to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration exemplary embodiments in which the invention may be practiced. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that various changes to the invention may be made without departing from the spirit and scope of the present invention. The following more detailed description of the embodiments of the invention is not intended to limit the scope of the invention, as claimed, but is presented for purposes of illustration only and not limitation to describe the features and characteristics of the invention, to set forth the best mode of carrying out the invention, and to sufficiently enable one skilled in the art to practice the invention. Accordingly, the scope of the invention is to be limited only by the following claims.

The economical 630MPa high-strength anti-seismic steel bar provided by the invention comprises the following chemical components in percentage by weight as shown in Table 1:

TABLE 1 chemical element composition and weight percentages (weight percentage%, balance Fe and unavoidable impurities) of each example

The ingredients of the above examples satisfy the following ranges:

c: 0.20 to 0.30%, Si: 0.40-0.80%, Mn: 1.40-1.60%, P: less than or equal to 0.035%, S: less than or equal to 0.035%, Nb: 0.010-0.020%, V: 0.050 to 0.100%, N: 0.008-0.015%, W: 0.010-0.020%, and the balance of Fe and inevitable impurity elements.

The effects of the elements in the steel for the anti-seismic steel bar are basically as follows:

c is a main element for strengthening the steel, can form solid solution and carbide in the steel to improve the strength and is beneficial to improving the yield ratio. The higher the C content, the higher the strength, but the lower the plasticity and toughness. Therefore, the content of C should be reduced as much as possible while ensuring that the strength of the steel can meet the use requirements. The content of C in the invention is 0.20-0.30%.

Si plays a role in solid solution strengthening, and mainly forms solid solution in ferrite to improve the strength of the steel, which is beneficial to improving the yield ratio, but can reduce the plasticity of the steel. The Si content of the invention is 0.40-0.80%.

Mn acts as solid solution strengthening, forms a solid solution mainly in pearlite to improve the strength of steel, and contributes to the improvement of the yield ratio, but at higher contents, it coarsens grains, increases brittleness, and also affects the weldability of steel. The Mn content of the invention is 1.40-1.60%.

Nb mainly plays a role in fine grain strengthening, and a small amount of Nb (less than or equal to 0.02 percent) can obviously improve the tensile strength and the yield strength of the steel without reducing the ductility index of the steel. The Nb content is 0.010-0.020%.

V mainly plays a role in precipitation strengthening, and the toughness of the steel is obviously improved by utilizing the fine dispersion distribution of V (C, N) second phase particles in the steel, but V resources are wasted due to excessive addition of V. The content of V in the invention is 0.05-0.10%.

N can improve the strength of steel, particularly in V-containing steel, N can promote precipitation of V and refine grains, VN steel has a precipitation strengthening effect which is nearly 2 times that of V steel, but aging hardening can be caused by the fact that the content of N is too high. The content of N in the invention is 0.008-0.015%.

W is a strong carbide-forming element, forms stable high-hardness carbides of W2C and WC in the steel, and also has a function of improving the strength of the steel and refining grains by partially containing tungsten in the austenite in a solid solution state. However, too high W content not only wastes resources but also deteriorates the elongation properties of the steel. The content of W in the invention is 0.010-0.020%.

Among the above elements, a small amount of W element is added in addition to conventional reinforcing elements such as C, Si, Mn, V, Nb, etc., whereby stable W is formed in steel₂(C, N) and W (C, N) to improve the strength of the steel.

W₂(C, N) and W (C, N) can play a role in inhibiting grain growth, ensure the ductility of steel, namely, by utilizing the formula, enough carbonitride precipitation is ensured, the precipitation strengthening effect of V, Nb and Mo is fully exerted, and the strength requirement is met. Through 1.35[ C ]]+0.8[N]≤0.5[W]+0.2[V]+0.3[Nb]+0.25[Si]+0.1[Mn]The element control of (1) is achieved.

The rolling process of the austenite non-recrystallization zone is adopted, the growth of crystal grains is inhibited, meanwhile, a large amount of dislocation and sub-crystal are promoted to be formed in the crystal grains, on the premise of ensuring the performance, the adding amount of micro-alloy elements such as V, Nb is greatly reduced, a small amount of W element is added to make up for the strength reduction caused by the reduction of V and Nb, namely, the formula ensures that the rolling of the austenite non-recrystallization zone is realized under the condition of ensuring the proper proportion of W and V, Nb elements. The element control is carried out by 0.1 ≦ Mo/([ V ] + [ Nb ]) ≦ 0.3.

The invention relates to a production method of an economical 630MPa high-strength anti-seismic steel bar, which comprises the following steps:

s1, smelting molten steel, controlling the carbon content at the smelting end point, stopping slag and tapping, and adding ferrotungsten in the tapping process of the smelting furnace; the W content of the ferrotungsten is 70-80%, and the ferrotungsten is added when tapping 3/5.

S2, refining in an LF furnace; the refining time of the LF furnace is more than or equal to 20min, and the yield of W is more than or equal to 95%.

And S3, continuously casting into a required blank.

S4, rolling an austenite non-recrystallization region, wherein the rolling of the austenite non-recrystallization region comprises the following steps:

(1) the heating temperature range is as follows: 1080-1180 ℃; the soaking temperature range is as follows: 1030-1130 ℃, the soaking time range is as follows: 80-120 min; the method is favorable for austenitizing the steel and promoting the dissolution of Si, Mn, V, Nb and W in austenite, and the square billet is cooled by water spray on a conveying roller way.

(2) The initial rolling temperature range is as follows: 950-1050 ℃; rolling by 6 frames of rough rolling mill set with 20% of deformation, rolling by 6 frames of middle rolling mill set with 20% of deformation, and arranging a water spray cooling device between the middle rolling mill set and the finishing mill set.

(3) The finishing mill temperature range is: 900-950 ℃; the steel is rolled in an austenite non-recrystallization region by a 6-frame finishing mill group, the large deformation amount is 60 percent, the transformation from gamma austenite to alpha ferrite + P pearlite is promoted by utilizing the low temperature and the large deformation amount, ferrite grains are refined, a large amount of dislocation is promoted to be formed in the grains, and the toughness of the steel is improved.

S5, rapidly cooling after rolling, and loading on a cooling bed, wherein the temperature range of the upper cooling bed for returning red is as follows: 800-900 ℃. And a rapid water cooling device is arranged behind the finishing mill, the temperature of red returning on the cooling bed is controlled to be 800-900 ℃ after the rapid cooling after the rolling, as shown in figure 1, an ideal fine-grain structure mainly comprising ferrite and pearlite is obtained, the grain size reaches 9 grades and above, and the precipitation of second-phase particles of V (C, N) and NbC is promoted, so that the toughness of the steel bar is improved.

Example 1

The chemical composition and the weight percentage content of the economical 630MPa high-strength anti-seismic steel bar for the embodiment are shown in the embodiment 1 in the table 1.

The production method of the economical 630MPa high-strength anti-seismic steel bar of the embodiment comprises the following steps based on chemical components of the embodiment:

s1, carrying out converter steelmaking, controlling the carbon content at the smelting end point to be 0.06% C, stopping slag and tapping, adding ferrotungsten when tapping 3/5, controlling the W content of ferrotungsten to be 70-80%, and adding ferrotungsten when tapping 3/5.

S2, refining in an LF furnace; the refining time of the LF furnace is more than or equal to 20min, and the yield of W is more than or equal to 95%.

And S3, continuously casting into square billets of 150 x 150 mm.

S4, rolling an austenite non-recrystallization region, wherein the rolling of the austenite non-recrystallization region comprises the following steps:

(1) the heating temperature range is as follows: 1080 ℃; the soaking temperature range is as follows: the soaking time range is as follows at 1030 ℃: 120 min;

(2) the initial rolling temperature range is as follows: 950 ℃; rolling by 6 frames of rough rolling mill set with 20% of deformation, rolling by 6 frames of middle rolling mill set with 20% of deformation, and arranging a water spray cooling device between the middle rolling mill set and the finishing mill set.

(3) The finishing mill temperature range is: 900 ℃; rolling the steel in an austenite non-recrystallization region by a 6-frame finishing mill group, wherein the deformation is 60%, the transformation of gamma austenite to alpha ferrite + P pearlite is promoted by utilizing low temperature and large deformation, ferrite grains are refined, a large amount of dislocation is promoted to be formed in the grains, and the toughness of the steel is improved.

S5, rapidly cooling after rolling, and loading on a cooling bed, wherein the temperature range of the upper cooling bed for returning red is as follows: 800 ℃.

The mechanical properties of the obtained steel for the anti-seismic reinforcing steel bar are shown in table 2 after three tests:

table 2 mechanical properties of steel for earthquake resistant reinforcing bar of example 1

ReL(MPa)	Rm(MPa)	High yield ratio (R)m/ReL)	Yield ratio (R)eL/630)	A(％)	Agt(％)
						657	832	1.27	1.04	18.5	10.6
655	820	1.25	1.04	19.5	11.5
						660	852	1.29	1.05	20.0	9.5

Example 2

The chemical composition and the weight percentage content of the economical 630MPa high-strength anti-seismic steel bar for the embodiment are shown in the embodiment 2 in the table 1.

The production method of the economical 630MPa high-strength anti-seismic steel bar of the embodiment comprises the following steps based on chemical components of the embodiment:

s1, carrying out converter steelmaking, controlling the carbon content at the smelting end point to be 0.07% C, stopping slag and tapping, adding ferrotungsten when tapping 3/5, controlling the W content of ferrotungsten to be 70-80%, and adding ferrotungsten when tapping 3/5.

S2, refining in an LF furnace; the refining time of the LF furnace is more than or equal to 20min, and the yield of W is more than or equal to 95%.

And S3, continuously casting into square billets of 150 x 150 mm.

S4, rolling an austenite non-recrystallization region, wherein the rolling of the austenite non-recrystallization region comprises the following steps:

(1) the heating temperature range is as follows: 1180 deg.C; the soaking temperature range is as follows: 1130 ℃, soaking time ranges are: 80 min;

(2) the initial rolling temperature range is as follows: 1050 ℃; rolling by 6 frames of rough rolling mill set with 20% of deformation, rolling by 6 frames of middle rolling mill set with 20% of deformation, and arranging a water spray cooling device between the middle rolling mill set and the finishing mill set.

(3) The finishing mill temperature range is: 950 ℃; rolling the steel in an austenite non-recrystallization region by a 6-frame finishing mill group, wherein the deformation is 60%, the transformation of gamma austenite to alpha ferrite + P pearlite is promoted by utilizing low temperature and large deformation, ferrite grains are refined, a large amount of dislocation is promoted to be formed in the grains, and the toughness of the steel is improved.

S5, rapidly cooling after rolling, and loading on a cooling bed, wherein the temperature range of the upper cooling bed for returning red is as follows: at 900 ℃.

The mechanical properties of the obtained steel for the anti-seismic reinforcing steel bar are shown in table 3 after three tests:

table 3 mechanical properties of steel for earthquake resistant reinforcing bar of example 1

ReL(MPa)	Rm(MPa)	Yield ratio (Rm/ReL)	Flexion ratio (ReL/630)	A(％)	Agt(％)
						684	865	1.26	1.09	18.0	9.0
674	845	1.25	1.07	19.0	9.5
						670	845	1.26	1.06	20.6	12.0

Example 3

The chemical composition and the weight percentage content of the economical 630MPa high-strength anti-seismic steel bar steel are shown in Table 1 as example 3.

The production method of the economical 630MPa high-strength anti-seismic steel bar of the embodiment comprises the following steps based on chemical components of the embodiment:

s1, carrying out converter steelmaking, controlling the carbon content at the smelting end point to be 0.08% C, stopping slag and tapping, adding ferrotungsten when tapping 3/5, controlling the W content of ferrotungsten to be 70-80%, and adding ferrotungsten when tapping 3/5.

S2, refining in an LF furnace; the refining time of the LF furnace is more than or equal to 20min, and the yield of W is more than or equal to 95%.

And S3, continuously casting into square billets of 150 x 150 mm.

S4, rolling an austenite non-recrystallization region, wherein the rolling of the austenite non-recrystallization region comprises the following steps:

(1) the heating temperature range is as follows: 1130 ℃; the soaking temperature range is as follows: 1080 ℃, and the soaking time range is as follows: 100 min;

(2) the initial rolling temperature range is as follows: 1000 ℃; rolling by 6 frames of rough rolling mill set with 20% of deformation, rolling by 6 frames of middle rolling mill set with 20% of deformation, and arranging a water spray cooling device between the middle rolling mill set and the finishing mill set.

(3) The finishing mill temperature range is: 925 ℃; rolling the steel in an austenite non-recrystallization region by a 6-frame finishing mill group, wherein the deformation is 60%, the transformation of gamma austenite to alpha ferrite + P pearlite is promoted by utilizing low temperature and large deformation, ferrite grains are refined, a large amount of dislocation is promoted to be formed in the grains, and the toughness of the steel is improved.

S5, rapidly cooling after rolling, and loading on a cooling bed, wherein the temperature range of the upper cooling bed for returning red is as follows: 850 ℃.

The mechanical properties of the obtained steel for the anti-seismic reinforcing steel bar are shown in table 3 after three tests:

table 3 mechanical properties of steel for earthquake resistant reinforcing bar of example 1

ReL(MPa)	Rm(MPa)	Yield ratio (Rm/ReL)	Flexion ratio (ReL/630)	A(％)	Agt(％)
						679	863	1.27	1.08	18.2	9.3
669	843	1.26	1.06	19.2	9.8
						665	843	1.27	1.06	20.8	12.3

In the above examples, R_eLIs the yield strength; r_mIs tensile strength; high yield ratio (R)_m/R_eL)，R_mFor measured tensile strength, R_eLMeasured yield strength; yield ratio (R)_eL/635)，630 is the yield strength characteristic value of the steel bar, and the unit is MPa; a is elongation after fracture; a. the_gtElongation at maximum force.