CN111155032A

CN111155032A - Rare earth high-performance bridge steel plate with yield strength of 500MPa and production method thereof

Info

Publication number: CN111155032A
Application number: CN202010049486.3A
Authority: CN
Inventors: 杨雄; 高军; 黄利; 姜秉坤; 卢晓禹; 王海明
Original assignee: Baotou Iron and Steel Group Co Ltd
Current assignee: Baotou Iron and Steel Group Co Ltd
Priority date: 2020-01-16
Filing date: 2020-01-16
Publication date: 2020-05-15

Abstract

The invention discloses a rare earth high-performance bridge steel plate with 500 MPa-grade yield strength, which comprises the following chemical components in percentage by mass: 0.06-0.08% of C, 0.20-0.30% of Si, 1.45-1.65% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, 0.035-0.045% of Nb, 0.05-0.07% of V, 0.010-0.020% of Ti, 0.15-0.25% of Cu, 0.15-0.25% of Ni, 0.15-0.25% of Cr, 0.024-0.034% of Als, and 0.0005-0.0030% of Ce. Its preparing process is also disclosed. The steel plate has yield strength of more than 500MPa, low yield ratio, good low-temperature toughness, cold formability, welding performance and corrosion resistance.

Description

Rare earth high-performance bridge steel plate with yield strength of 500MPa and production method thereof

Technical Field

The invention relates to the field of ferrous metallurgy, in particular to a rare earth high-performance bridge steel plate with the yield strength of 500MPa and a production method thereof.

Background

With the development of large steel structure bridges to full-welded structures and high parameters, the requirements on the safety and reliability of bridge structures are more and more strict, and simultaneously, higher requirements on the performance of bridge steel plates are provided, so that the bridge steel plates not only have high strength to meet the requirements on structure light weight, but also have excellent low-temperature toughness, weldability, weather resistance and the like to meet the requirements on safety, reliability, long service life and the like of the steel structures. Under these circumstances, the united states of america has proposed a concept of high performance steel (HPS steel for short), which means that the steel has excellent weldability, low-temperature impact toughness, and particularly corrosion resistance, in addition to high strength. For example, the high-performance bridge steel is successfully developed by the HPS-70W, the HPS100W in the United states, and domestic Wu steel, saddle steel, dance steel, first steel, south steel and the like.

Patent CN104946980A discloses a TMCP + tempering type 550 MPa-grade corrosion-resistant bridge steel and a production method thereof, wherein the bridge steel with high toughness and good welding performance is obtained by adopting C-Mn-Cu-V-W-Sn series microalloy element composite reinforcement and through a TMCP + tempering process. However, the W, Sn element is added in the chemical composition, so that the control is difficult, the tempering process is needed, and the cost is increased.

Patent CN105063509A discloses a bridge structural steel with 500 MPa-grade yield strength and a production method thereof, and a bridge steel plate with high strength, excellent low-temperature toughness and excellent welding performance is obtained through controlled rolling, controlled cooling and tempering processes. However, the component B increases the crack sensitivity of the steel, and the steel plate adopts a segmented control cooling process, which increases the production difficulty and is not beneficial to stable batch production.

Patent CN101892431A discloses weather-resistant bridge steel with 500 MPa-level yield strength in a hot rolling state and a manufacturing method thereof, and the weather-resistant bridge steel with 500MPa yield strength and corrosion resistance index I larger than 6.5 is obtained through smelting, continuous casting, heating, controlled rolling and controlled cooling. However, the contents of Cr, Ni and Cu in the components are high, and the noble element Mo is also contained, so that the production cost of the steel plate is increased, and the requirements on welding wires and welding processes are more severe, and the application is not facilitated.

Disclosure of Invention

The invention aims to provide a rare earth high-performance bridge steel plate with the yield strength of 500MPa, and solves the problem.

In order to solve the technical problems, the invention adopts the following technical scheme:

a rare earth high-performance bridge steel plate with 500 MPa-grade yield strength comprises the following chemical components in percentage by mass: c: 0.06-0.08%, Si: 0.20 to 0.30%, Mn: 1.45-1.65%, P: less than or equal to 0.015%, S: less than or equal to 0.008 percent, Nb: 0.035-0.045%, V: 0.05-0.07%, Ti: 0.010-0.020%, Cu: 0.15 to 0.25%, Ni: 0.15-0.25%, Cr: 0.15-0.25%, Als: 0.024-0.034%, rare earth Ce: 0.0005 to 0.0030%, and the balance Fe and inevitable impurities.

Further, the paint comprises the following chemical components in percentage by mass: c: 0.06%, Si: 0.20%, Mn: 1.49%, P: 0.013%, S: 0.002%, Nb: 0.043%, V: 0.06%, Ti: 0.015%, Cu: 0.22%, Ni: 0.21%, Cr: 0.24%, Als: 0.025%, rare earth Ce: 0.0010%, the balance being Fe and unavoidable impurities.

Further, the paint comprises the following chemical components in percentage by mass: c: 0.07%, Si: 0.24%, Mn: 1.52%, P: 0.012%, S: 0.003%, Nb: 0.035%, V: 0.05%, Ti: 0.011%, Cu: 0.23%, Ni: 0.22%, Cr: 0.23%, Als: 0.024%, rare earth Ce: 0.0015%, and the balance of Fe and inevitable impurities.

Further, the paint comprises the following chemical components in percentage by mass: c: 0.08%, Si: 0.27%, Mn: 1.55%, P: 0.010%, S: 0.002%, Nb: 0.038%, V: 0.07%, Ti: 0.011%, Cu: 0.22%, Ni: 0.24%, Cr: 0.22%, Als: 0.028%, rare earth Ce: 0.0027%, and the balance of Fe and inevitable impurities.

A production method of a rare earth high-performance bridge steel plate with 500 MPa-level yield strength comprises the following steps:

1) smelting and casting

Adding prepared low-phosphorus (less than or equal to 0.010 percent), low-sulfur (less than or equal to 0.005 percent), low-oxygen (less than or equal to 0.0040 percent), low-nitrogen (less than or equal to 0.0060 percent) high-quality scrap steel and other calculated and prepared alloys into a laboratory 100kg vacuum smelting furnace, starting to melt and smelt after vacuumizing, casting into a rectangular steel die after melting, and casting into a rectangular billet with the size of 220 multiplied by 250 multiplied by 300 mm.

2) Heating and rolling:

the method comprises the steps of loading a steel billet into a high-temperature resistance furnace by using a manipulator, heating the steel billet at 1200-1220 ℃, wherein the total in-furnace time is more than or equal to 240min, ensuring the uniform temperature of the steel billet, and when the steel billet meets the heating requirement, sending the steel billet to a phi 750 x 550mm experimental rolling mill by using the manipulator, controlling the rolling process in two stages, namely rolling in an austenite recrystallization region and rolling in an austenite non-recrystallization region, wherein the start rolling temperature is 1130-1180 ℃, the 1 st-2 nd pass reduction is more than 10%, and then at least 1-2 th pass reduction is controlled to be more than 25% so as to fully refine original austenite grains, wherein when rolling in the austenite non-recrystallization region, the rolling in the stage enables austenite to elongate, the area of grain boundaries is increased, meanwhile, a large number of deformation bands are introduced into the grains, the nucleation density and nucleation points are increased when gamma → α phase transformation is carried out later, α grains are further refined, the start rolling temperature is set to be less than or equal to 930 ℃, and the thickness of an intermediate billet is 2.0-3..

3) Cooling the mixture

And after the rolling is controlled to be finished, the steel plate enters a laminar flow cooling area, is cooled to 550-580 ℃ at a cooling speed of 10-15 ℃/s, and then enters a cooling bed for cooling.

Further, heating the steel billet to 1210 ℃, keeping the total furnace time for 252 minutes, performing first-stage rolling on a rolling mill, namely rolling in an austenite recrystallization zone, wherein the initial rolling temperature is 1176 ℃, the reduction of the 1 st to 2 nd pass is more than 10%, then at least the reduction of the 1 st to 2 th pass is controlled to be more than 25%, when the thickness of a rolled piece is 45mm, heating the rolled piece on a roller table to 930 ℃, then performing second-stage rolling, namely rolling in an austenite non-recrystallization zone, wherein the final rolling temperature is 830 ℃, the thickness of a finished steel plate is 14mm, and after the rolling is finished, feeding the steel plate into a laminar cooling device, and cooling the steel plate to 552 ℃ at the speed of 12 ℃/s.

Further, the heating temperature of the steel billet is 1220 ℃, the total in-furnace time is kept for 256 minutes, the initial rolling temperature of the first stage rolling is 1175 ℃, the thickness of the intermediate billet is 60mm, the initial rolling temperature of the second stage rolling is 925 ℃, the final rolling temperature is 836 ℃, the thickness of the finished steel plate is 20mm, and after the rolling is finished, the steel plate enters a laminar cooling device and is cooled to 561 ℃ at the speed of 13 ℃/s.

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

the high-performance bridge steel plate with yield strength of more than 500MPa, low yield ratio, good low-temperature toughness, cold formability, welding performance and corrosion resistance can be obtained by reasonable chemical component design and the production method, and the high-performance bridge steel plate has the characteristics of simple preparation process flow, short production period and low production cost.

Drawings

The invention is further illustrated in the following description with reference to the drawings.

FIG. 1 is a metallographic structure diagram of a steel sheet according to example 2 of the present invention.

Detailed Description

Example 1

Smelting according to the chemical components shown in the table 1, casting the materials into a steel billet, heating the steel billet to 1210 ℃, keeping the furnace time for 252 minutes, carrying out first-stage rolling on an experimental rolling mill, namely rolling in an austenite recrystallization region, wherein the starting rolling temperature is 1176 ℃, the reduction of 1 st to 2 nd passes is more than 10%, the reduction of at least 1 to 2 passes is controlled to be more than 25%, when the thickness of a rolled piece is 45mm, heating the rolled piece on a roller way to 930 ℃, and then carrying out second-stage rolling, namely rolling in an austenite non-recrystallization region. The final rolling temperature is 830 ℃, and the thickness of the finished steel plate is 14 mm. And after rolling, the steel plate enters a laminar flow cooling device, and is cooled to 552 ℃ at the speed of 12 ℃/s, and finally the steel plate is obtained.

Example 2

The implementation mode is the same as that of example 1, wherein the heating temperature is 1220 ℃, the total in-furnace time is kept for 256 minutes, the initial rolling temperature of the first stage rolling is 1175 ℃, the thickness of the intermediate blank is 60mm, the initial rolling temperature of the second stage rolling is 925 ℃, the final rolling temperature is 836 ℃, and the thickness of the finished steel plate is 20 mm. And after rolling, the steel plate enters a laminar flow cooling device, and is cooled to 561 ℃ at the speed of 13 ℃/s, and finally the steel plate can be obtained. The microstructure of this steel sheet is shown in FIG. 1, and the microstructure mainly includes bainite and fine ferrite.

Example 3

The procedure is as in example 1, wherein the heating temperature is 1226 ℃ and the total in-furnace time is 260 minutes; the initial rolling temperature of the first stage rolling is 1180 ℃, and the thickness of the intermediate billet is 80 mm; the initial rolling temperature of the second stage of rolling is 930 ℃, the final rolling temperature is 850 ℃, and the thickness of the finished steel plate is 40 mm; and after rolling, the steel plate enters a laminar flow cooling device, and is cooled to 572 ℃ at the speed of 15 ℃/s, and finally the steel plate is obtained.

TABLE 1 chemical composition (wt%) of inventive examples 1 to 3

Examples	C	Si	Mn	P	S	Nb	V	Ti	Cu	Ni	Cr	Als	Ce
														1	0.06	0.20	1.49	0.013	0.002	0.043	0.06	0.015	0.22	0.21	0.24	0.025	0.0010
2	0.07	0.24	1.52	0.012	0.003	0.035	0.05	0.011	0.23	0.22	0.23	0.024	0.0015
														3	0.08	0.27	1.55	0.010	0.002	0.038	0.07	0.011	0.22	0.24	0.22	0.028	0.0027

The mechanical properties of the steel sheets of examples 1 to 3 of the present invention were examined, and the results are shown in Table 2.

TABLE 2 mechanical Properties of Steel sheets according to examples 1 to 3 of the present invention

The bridge steel provided by the embodiment of the invention has the yield strength of more than or equal to 500MPa, the tensile strength of more than or equal to 630MPa, the elongation of more than or equal to 18 percent, the yield ratio of less than or equal to 0.86 and the longitudinal impact energy KV2 of more than or equal to 120J at minus 40 ℃.

Table 3 shows the weld crack sensitivity Pcm and the corrosion resistance index I of the steels according to the examples of the present invention.

TABLE 3 weld crack susceptibility Pcm and Corrosion resistance index I for inventive examples

The smaller the value of the welding crack sensitivity coefficient Pcm is, the better the welding performance of the steel is, and the welding cold crack is not easy to generate during welding; the larger the corrosion resistance index I value is, the better the corrosion resistance is.

From the results of the above examples, it can be seen that the high-performance bridge steel with 500MPa yield strength has excellent mechanical properties, especially low-temperature toughness, and simultaneously has good welding performance and atmospheric corrosion resistance, and can be used for manufacturing large-span highways, railways, river-crossing bridges and river-crossing bridges.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. The rare earth high-performance bridge steel plate with the yield strength of 500MPa is characterized by comprising the following chemical components in percentage by mass: c: 0.06-0.08%, Si: 0.20 to 0.30%, Mn: 1.45-1.65%, P: less than or equal to 0.015%, S: less than or equal to 0.008 percent, Nb: 0.035-0.045%, V: 0.05-0.07%, Ti: 0.010-0.020%, Cu: 0.15 to 0.25%, Ni: 0.15-0.25%, Cr: 0.15-0.25%, Als: 0.024-0.034%, rare earth Ce: 0.0005 to 0.0030%, and the balance Fe and inevitable impurities.

2. The rare earth high-performance bridge steel plate with the yield strength of 500MPa is characterized by comprising the following chemical components in percentage by mass: c: 0.06%, Si: 0.20%, Mn: 1.49%, P: 0.013%, S: 0.002%, Nb: 0.043%, V: 0.06%, Ti: 0.015%, Cu: 0.22%, Ni: 0.21%, Cr: 0.24%, Als: 0.025%, rare earth Ce: 0.0010%, the balance being Fe and unavoidable impurities.

3. The rare earth high-performance bridge steel plate with the yield strength of 500MPa is characterized by comprising the following chemical components in percentage by mass: c: 0.07%, Si: 0.24%, Mn: 1.52%, P: 0.012%, S: 0.003%, Nb: 0.035%, V: 0.05%, Ti: 0.011%, Cu: 0.23%, Ni: 0.22%, Cr: 0.23%, Als: 0.024%, rare earth Ce: 0.0015%, and the balance of Fe and inevitable impurities.

4. The rare earth high-performance bridge steel plate with the yield strength of 500MPa is characterized by comprising the following chemical components in percentage by mass: c: 0.08%, Si: 0.27%, Mn: 1.55%, P: 0.010%, S: 0.002%, Nb: 0.038%, V: 0.07%, Ti: 0.011%, Cu: 0.22%, Ni: 0.24%, Cr: 0.22%, Als: 0.028%, rare earth Ce: 0.0027%, and the balance of Fe and inevitable impurities.

5. The production method of the rare earth high-performance bridge steel plate with the yield strength of 500MPa according to any one of claims 1 to 4, characterized by comprising the following steps:

1) smelting and casting

The prepared low-phosphorus: less than or equal to 0.010%), low sulfur: 0.005%) and hypoxia: less than or equal to 0.0040%), low nitrogen: adding high-quality scrap steel less than or equal to 0.0060% and other calculated and prepared alloys into a vacuum smelting furnace, starting to melt and smelt after vacuumizing, casting into a rectangular steel die after melting, and casting into a steel billet;

2) heating and rolling:

loading a steel billet into a high-temperature resistance furnace by using a manipulator, heating the steel billet at 1200-1220 ℃, wherein the total in-furnace time is more than or equal to 240min, ensuring the uniform temperature of the steel billet, and when the steel billet meets the heating requirement, conveying the steel billet to a rolling mill by using the manipulator, wherein a two-stage control rolling process is adopted, namely, the rolling in an austenite recrystallization region and the rolling in an austenite non-recrystallization region are adopted, the start rolling temperature is 1130-1180 ℃, the 1-2 pass reduction is more than 10%, and at least 1-2 pass reduction rate is controlled to be more than 25% so as to fully refine original austenite grains;

3) cooling the mixture

And after the rolling is controlled to be finished, the steel plate enters a laminar cooling area and is cooled to 550-580 ℃ at a cooling speed of 10-15 ℃/s.

6. The production method of claim 5, wherein the billet is heated to 1210 ℃ for 252 minutes, the first stage rolling, i.e. austenite recrystallization zone rolling, is performed on a rolling mill at 1176 ℃, the reduction of the 1 st to 2 nd pass is more than 10%, the reduction of at least 1 st to 2 th pass is controlled to be more than 25%, the temperature is kept to 930 ℃ on a roller table when the thickness of the rolled piece is 45mm, the second stage rolling, i.e. austenite non-recrystallization zone rolling, the final rolling temperature is 830 ℃, the thickness of the finished product steel plate is 14mm, and the steel plate enters a laminar cooling device after the rolling is finished and is cooled to 552 ℃ at the speed of 12 ℃/s.

7. The production method of claim 5, wherein the heating temperature of the billet is 1220 ℃, the total in-furnace time is kept for 256 minutes, the initial rolling temperature of the first stage rolling is 1175 ℃, the thickness of the intermediate billet is 60mm, the initial rolling temperature of the second stage rolling is 925 ℃, the final rolling temperature is 836 ℃, the thickness of the finished steel plate is 20mm, and after the rolling is finished, the steel plate enters a laminar cooling device and is cooled to 561 ℃ at the speed of 13 ℃/s.