CN113528972B

CN113528972B - 460 MPa-level shock-resistant fire-resistant super-thick steel plate and production method thereof

Info

Publication number: CN113528972B
Application number: CN202111089850.XA
Authority: CN
Inventors: 杜平; 武凤娟; 曲锦波
Original assignee: Jiangsu Shagang Iron and Steel Research Institute Co Ltd
Current assignee: Jiangsu Shagang Iron and Steel Research Institute Co Ltd
Priority date: 2021-09-17
Filing date: 2021-09-17
Publication date: 2022-01-18
Anticipated expiration: 2041-09-17
Also published as: CN113528972A

Abstract

The invention discloses a 460 MPa-level shock-resistant fire-resistant super-thick steel plate and a production method thereof. The steel plate comprises the following chemical components: 0.06-0.09% of carbon; 0.2 to 0.3 percent of silicon; 1.45-1.55% of manganese; 0.3-0.45% of chromium; 0.02-0.05% of aluminum; 0.025-0.035% of niobium; 0.2-0.3% of molybdenum; 0.01-0.02% of titanium; less than 0.013% of phosphorus, less than 0.003% of sulfur and the balance of iron and impurities; is prepared by adopting TMCP technology; wherein water cooling is carried out for 1-2 times during the rough rolling period, then water cooling and finish rolling are carried out on the intermediate billet, and the finish rolling is carried out at the beginning of 810-830 ℃; and in the cooling process, water cooling is carried out to 250-300 ℃ through 2-3 times, the swing air cooling is carried out between two adjacent times of water cooling for 60-90 s, and the cooling speed is 3-8 ℃/s during each time of water cooling. The steel plate has low cost and excellent comprehensive performance.

Description

460 MPa-level shock-resistant fire-resistant super-thick steel plate and production method thereof

Technical Field

The invention belongs to the technical field of alloy steel production, and relates to a 460 MPa-level shock-resistant fire-resistant super-thick steel plate and a production method thereof.

Background

With the popularization of high-rise buildings and assembly type buildings, a steel structure is taken as an important structural form of modern buildings and becomes the development direction of the current buildings; the high-rise building pays more attention to safety, and the steel for the building structure is required to have good anti-seismic performance and fire resistance while ensuring the conventional mechanical property and welding performance.

When the temperature reaches 400 ℃, the yield strength of the traditional common construction steel is reduced to half of the strength of the room temperature, and when the temperature reaches 600 ℃, the strength is basically lost, so that the large-scale steel structure construction requires that a layer of fireproof coating is coated on the surface of a steel structure to enhance the capability of resisting fire. The method for spraying the refractory material can multiply increase the building cost, prolong the construction period, reduce the indoor effective use area and cause the splashing of the spraying operation to pollute the environment. Therefore, it is required to improve the fire resistance and the seismic resistance of the steel sheet itself to fundamentally improve the safety of the steel structure in the construction.

In the existing steel plate manufacturing, in order to improve the fire resistance and the earthquake resistance, a large amount of chemical component systems of precious metals such as Mo, V, rare earth and the like are usually adopted, or heat treatment procedures such as normalizing, tempering, quenching and tempering are added, so that the defects of high alloy cost, high production cost, long production period and the like exist.

Further, with respect to the super-thick steel sheet, there is no prior art for improving the resistance to the lamellar tearing.

Disclosure of Invention

The invention aims to provide an anti-seismic fire-resistant super-thick steel plate and a production method thereof, and the super-thick steel plate with 460MPa grade, low yield ratio, high low-temperature toughness, excellent fire resistance and excellent lamellar tearing resistance is obtained on the basis of low alloy cost and short production flow by mutual matching of chemical components and process methods.

In order to achieve the above object, an embodiment of the present invention provides a method for producing a 460 MPa-grade earthquake-resistant and fire-resistant super-thick steel plate, which comprises the steps of:

(1) molten steel smelting is carried out by adopting molten iron desulphurization, smelting and refining, and P in the finally obtained molten steel is controlled to be less than 0.013 percent and S is controlled to be less than 0.003 percent in percentage by mass;

(2) continuously casting the molten steel obtained in the step (1) into a continuous casting blank with the thickness of 220 mm-320 mm, and stacking the continuous casting blank for slow cooling; the temperature of the tundish during continuous casting is 1534-1549 ℃, and the casting speed of the continuous casting machine is 0.6-0.8 m/s; the chemical components of the obtained continuous casting slab comprise the following components in percentage by mass: 0.06-0.09% of C, 0.20-0.30% of Si, 1.45-1.55% of Mn, 0.30-0.45% of Cr, 0.020-0.050% of Al, 0.025-0.035% of Nb, 0.20-0.30% of Mo, 0.010-0.020% of Ti, and the balance of iron and inevitable impurities;

(3) conveying the unstacked continuous casting blank to a heating furnace for heating, wherein the heating temperature is 1180-1250 ℃, and the heating time is controlled to be 9-10 min/cm according to the thickness of the continuous casting blank;

(4) after the continuous casting slab exits from the heating furnace, carrying out multi-pass rough rolling to obtain an intermediate slab with the thickness of 120-180 mm, wherein the reduction of each pass is not less than 25mm, the initial rolling temperature is 1060-1120 ℃, the final rolling temperature is 1020-1080 ℃, and water cooling is carried out for 1-2 times during the rolling of the continuous casting slab to the intermediate slab; performing water cooling on the obtained intermediate blank, then performing finish rolling for more than 6 times to obtain a steel plate with the thickness of 60-100 mm, wherein the final reduction of the three times is not more than 6mm, the initial rolling temperature is 810-830 ℃, and the final rolling temperature is 780-800 ℃;

(5) carrying out water cooling on the rolled steel plate for 2-3 times, swinging and air cooling for 60-90 s between two adjacent times of water cooling, and finally cooling the steel plate to 250-300 ℃; controlling the cooling rate of each water cooling to be 3-8 ℃/s;

(6) and (5) straightening, stacking, slow cooling, cutting and finishing the steel plate obtained in the step (5) to obtain a steel plate finished product.

Preferably, V, W and rare earth elements are not added in step (1).

Preferably, step (1) is: molten iron desulphurization, converter smelting, LF and RH refining are adopted for molten steel smelting, and P in the finally obtained molten steel is controlled to be less than 0.013 percent and S is controlled to be less than 0.003 percent in percentage by mass; wherein, the converter smelting process adopts a top-bottom combined blowing process, soft blowing is carried out for more than 20min after degassing of the RH refining process, and the vacuum treatment time is more than 15 min.

Preferably, unstacking is carried out after the stacking slow cooling treatment time of the step (2) is 48 hours; and/or unstacking the stacks in the step (6) after 48 hours of stack slow cooling treatment.

Preferably, in the step (4), a spray water tank is arranged at an outlet of the roughing mill, and the continuous casting billet is rolled into an intermediate billet by the roughing mill for N times, wherein N is a positive integer larger than or equal to 6;

wherein, the step of carrying out water cooling for 1-2 times during the process of rolling the continuous casting blank into the intermediate blank comprises the following steps: and when the blank passes through the roughing mill and enters a spray water tank, performing water cooling in 1-2 odd-numbered passes in the previous N-1 passes.

Preferably, in the step (4), in the process of roughly rolling the continuous casting billet into the intermediate billet, widening rolling and extension rolling are carried out on the billet; in the process of finish rolling the intermediate billet into a steel plate, only elongation rolling is performed on the billet, and the number of finish rolling passes is even.

Preferably, in the step (5), the speed of the roller way is controlled to be 0.2-0.5 m/s during each water cooling, and the steel plate is cooled by adopting the water pressure of 1.5 bar.

In order to achieve the above object, an embodiment of the present invention provides a 460 MPa-level earthquake-resistant and fire-resistant super-thick steel plate, which comprises the following chemical components by mass: 0.06-0.09% of C, 0.20-0.30% of Si, 1.45-1.55% of Mn, 0.30-0.45% of Cr, 0.020-0.050% of Al, 0.025-0.035% of Nb, 0.20-0.30% of Mo, 0.010-0.020% of Ti, less than 0.013% of P, less than 0.003% of S, and the balance of iron and inevitable impurities;

the steel plate is prepared by molten iron desulphurization, smelting, refining, continuous casting, blank heating, controlled rolling, controlled cooling, straightening, stacking slow cooling, cutting and finishing in sequence; wherein:

in the continuous casting process, continuously casting molten steel into a continuous casting blank with the thickness of 220-320 mm, and stacking the continuous casting blank for slow cooling; the temperature of the tundish during continuous casting is 1534-1549 ℃, and the casting speed of the continuous casting machine is 0.6-0.8 m/s;

in the blank heating procedure, conveying the unstacked continuous casting blank to a heating furnace for heating, wherein the heating temperature is 1180-1250 ℃, and the heating time is controlled to be 9-10 min/cm according to the thickness of the continuous casting blank;

in the controlled rolling procedure, after the continuous casting slab exits from the heating furnace, the continuous casting slab is roughly rolled into an intermediate slab with the thickness of 120 mm-180 mm for multiple times, the reduction of each time is not less than 25mm, the initial rolling temperature is 1060-1120 ℃, the final rolling temperature is 1020-1080 ℃, and water cooling is carried out for 1-2 times during the rolling of the continuous casting slab into the intermediate slab; performing water cooling on the obtained intermediate blank, then performing finish rolling for more than 6 times to obtain a steel plate with the thickness of 60-100 mm, wherein the final reduction of the three times is not more than 6mm, the initial rolling temperature is 810-830 ℃, and the final rolling temperature is 780-800 ℃;

in the controlled cooling process, the rolled steel plate is subjected to water cooling for 2-3 times, swinging air cooling is carried out between two adjacent times of water cooling for 60-90 s, and the steel plate is finally cooled to 250-300 ℃; and the cooling rate during each water cooling is controlled to be 3-8 ℃/s.

Preferably, the tensile strength of the obtained steel plate is more than or equal to 570MPa, the elongation is more than or equal to 20 percent, and the yield ratio is less than or equal to 0.80.

Preferably, the impact energy of the obtained steel plate at the low temperature of-40 ℃ is more than or equal to 150J, and the shrinkage of the Z-direction end face is more than or equal to 35 percent; d =2a when the cold bending property is 180 degrees, and the appearance is free of cracks, wherein d is the bending core diameter, and a is the thickness of the sample; the yield strength of the steel plate is more than 307MPa after the steel plate is subjected to heat preservation for 3 hours at 600 ℃.

Preferably, V, W and rare earth elements are not added in the smelting process and the refining process.

Preferably, the smelting process is carried out in a converter, and a top-bottom combined blowing process is adopted in the converter smelting process; the refining process is carried out in an LF furnace and an RH furnace in sequence, soft blowing is carried out for more than 20min after degassing of the RH refining process, and the vacuum treatment time is more than 15 min.

Preferably, in the continuous casting process, the continuous casting billets are stacked and slowly cooled for 48 hours, and then unstacked; and/or, stacking and slow cooling treatment is carried out for 48 hours after straightening, and then unstacking is carried out.

Preferably, in the controlled rolling procedure, a spray water tank is arranged at the outlet of the roughing mill, and the continuous casting billet is rolled into an intermediate billet by the roughing mill for N times, wherein N is a positive integer larger than or equal to 6; wherein, the step of carrying out water cooling for 1-2 times during the process of rolling the continuous casting blank into the intermediate blank comprises the following steps: and when the blank passes through the roughing mill and enters a spray water tank, performing water cooling in 1-2 odd-numbered passes in the previous N-1 passes.

Preferably, in the controlled rolling process, in the process of roughly rolling the continuous casting blank into an intermediate blank, widening rolling and extension rolling are carried out on the blank; in the process of finish rolling the intermediate billet into a steel plate, only elongation rolling is performed on the billet, and the number of finish rolling passes is even.

Preferably, in the controlled cooling process, the speed of the roller way is controlled to be 0.2-0.5 m/s during each water cooling, and the steel plate is cooled by adopting the water pressure of 1.5 bar.

Compared with the prior art, the invention has the beneficial effects that: through reasonable component design, Cr, Mo, Nb and Ti microalloy is added, process means in rolling and controlled rolling cooling are combined, particularly, under the condition that the content of a refractory element Mo is low and the refractory element such as V, W and rare earth elements is not contained, the cooling, rolling temperature and rolling reduction in the rolling process are controlled, and the whole means of cooling is controlled, heat treatment processes such as tempering, normalizing, quenching and tempering are not needed, so that the manufacturing of a 460MPa anti-seismic steel plate with the thickness of 60 mm-100 mm can be realized by using a continuous casting billet with the thickness of 250 mm-320 mm, the obtained steel plate has high strength, low yield ratio, low-temperature toughness, lamellar tearing resistance and excellent fire resistance, the alloy cost of the steel plate is reduced, the production process is simplified, the production period is shortened, and the production efficiency is improved.

Drawings

FIG. 1 is a metallographic structure diagram of a steel sheet in example 1;

FIG. 2 is a metallographic structure diagram of a steel sheet in example 2.

Detailed Description

The technical solution of the present invention is further described below with reference to specific embodiments, but the scope of protection claimed is not limited to the description.

The embodiment of the invention provides a production method of an ultra-thick steel plate and the ultra-thick steel plate prepared by the production method. The super-thick steel plate is a steel plate having a thickness of 60mm or more, and in the present embodiment, the thickness of the steel plate is 60mm to 100 mm.

Specifically, in the production method, steel smelting is carried out according to a preset chemical composition design scheme, and the obtained molten steel is cast into a continuous casting billet. Therefore, the chemical composition of the molten steel at the steel smelting end point, the chemical composition of the continuous casting billet and the chemical composition of the finally obtained steel plate all meet the preset chemical composition design scheme. The predetermined chemical composition design scheme is that the chemical composition comprises the following components in percentage by mass: 0.06-0.09% of C, 0.20-0.30% of Si, 1.45-1.55% of Mn, 0.30-0.45% of Cr, 0.020-0.050% of Al, 0.025-0.035% of Nb, 0.20-0.30% of Mo, 0.010-0.020% of Ti, less than 0.013% of P, less than 0.003% of S, and the balance of iron and inevitable impurities.

In the aspect of process flow, the production method comprises molten iron desulphurization, smelting, refining, continuous casting, billet heating, controlled rolling, controlled cooling, straightening, stacking slow cooling and cutting finishing in sequence. The details are as follows.

(1) Smelting steel

Smelting steel through a molten iron desulphurization process, a smelting process and a refining process, and regulating the content of each chemical element in the molten steel according to the preset chemical composition design scheme in the whole steel smelting process, wherein P is less than 0.013 percent and S is less than 0.003 percent in the finally obtained molten steel in percentage by mass.

(2) Continuous casting

Continuously casting molten steel finally obtained in the smelting process into a continuous casting blank with the thickness of 220 mm-320 mm, and stacking and slowly cooling the continuous casting blank; the temperature of the tundish during continuous casting is 1534-1549 ℃, and the casting speed of the continuous casting machine is 0.6-0.8 m/s. Thus, the center segregation of the continuous casting billet can be reduced, and the internal defects of internal cracks, shrinkage cavities and the like of the continuous casting billet are prevented.

(3) Heating of blanks

And conveying the unstacked continuous casting blank to a heating furnace for heating, wherein the heating temperature is 1180-1250 ℃, and the heating time is controlled to be 9-10 min/cm according to the thickness of the continuous casting blank. For example, for a continuous casting slab with the thickness of 300mm, the heating time is 270-300 min.

(4) Controlled rolling

And (4) rolling the continuous casting billet in two stages after the continuous casting billet is taken out of the heating furnace.

The first stage is a rough rolling stage, and the continuous casting blank is roughly rolled into an intermediate blank with the thickness of 120-180 mm through multiple passes; the reduction per pass is not less than 25mm, for example, 25 mm-40 mm; the initial rolling temperature is 1060-1120 ℃, and the final rolling temperature is 1020-1080 ℃; and carrying out water cooling for 1-2 times during the process of rolling the continuous casting blank into the intermediate blank.

The second stage is a finish rolling stage, after the finish rolling stage is finished and before the finish rolling stage is started, the intermediate blank obtained by the rough rolling is firstly subjected to water cooling for 2 times, for example, two cooling water tanks are arranged between the rough rolling mill and the finish rolling mill in the front and back directions, so that the intermediate blank is respectively subjected to water cooling when sequentially passing through the two cooling water tanks. Then, performing finish rolling for more than 6 times to obtain a steel plate with the thickness of 60 mm-100 mm, wherein the reduction of the final finish rolling for three times is not more than 6mm, for example, 2-6 mm; the initial rolling temperature is 810-830 ℃, and the final rolling temperature is 780-800 ℃.

Therefore, on one hand, the surface hardness of the blank is higher than the core hardness by carrying out water cooling during the rough rolling and carrying out water cooling on the transition section between the rough rolling and the finish rolling, so that the deformation and the penetration to the core in the rolling process are facilitated, and the uniformity of the surface and the core is improved; on the other hand, the transition section between water cooling, rough rolling and finish rolling is controlled during rough rolling, the water cooling and the reduction amount are controlled, and the rolling temperature in the rough rolling stage and the finish rolling stage is controlled, so that the rough rolling stage is maintained in an austenite recrystallization region for rolling, the finish rolling stage is maintained in a non-recrystallization region, namely a deformation induced phase transformation region for rolling, austenite crystal grains are fully refined, a bainite structure is obtained by combining with subsequent cooling, and precipitates are fine in size and are dispersed in the bainite structure, so that the fire resistance, the low-temperature toughness and the tensile strength are improved, and the good plate shape can be kept.

(5) Controlled cooling

Carrying out 2-3 times of water cooling on the rolled steel plate, and swinging and air cooling for 60-90 s between two adjacent times of water cooling, and finally cooling the steel plate to 250-300 ℃; wherein the cooling rate during each water cooling is controlled to be 3-8 ℃/s.

For example, after the steel plate finally leaves from the finishing mill, the steel plate firstly moves forwards on a cooling roller way, the cooling roller way is provided with a cooling water tank, the cooling water tank is provided with a plurality of rows of cooling water collecting pipes (provided with nozzles) positioned at the upper side and the lower side of the cooling roller way, when the steel plate moves forwards on the cooling roller way, the cooling water collecting pipes are opened to carry out the 1 st-time water cooling, and the cooling rate is maintained to be controlled within 3 ℃/s-8 ℃/s; after finishing (namely after being taken out of the cooling water tank), the steel plate swings and air-cools for 60-90 s; then, the steel plate is returned backwards on the cooling roller way, the cooling water header is started to carry out the 2 nd pass water cooling in the period, and the cooling rate is maintained to be controlled at 3 ℃/s-8 ℃/s; after finishing (namely after being taken out of the cooling water tank), the steel plate swings and air-cools for 60-90 s; and finally, moving the steel plate forward on the cooling roller way again, starting the cooling water header to carry out 3 rd pass water cooling in the period, and maintaining the cooling rate to be controlled at 3-8 ℃/s.

Thus, by combining the process means of controlled rolling and the controlled cooling, austenite grains can be fully refined through 2-3 times of low cooling rate cooling and swing air cooling between two times, a bainite structure can be obtained by combining subsequent cooling, and precipitates are fine in size and are dispersed in the bainite structure, so that the fire resistance, the low-temperature toughness and the tensile strength are improved, and the lamellar tearing resistance is improved.

And as the example, the reciprocating moving mode is carried out by utilizing the same section of cooling roller way, so that the method further has the advantages of low equipment cost, small construction site and the like.

(6) Finished product

And straightening, stacking, slowly cooling, cutting and finishing the cooled steel plate to obtain a finished steel plate.

As can be seen from the above, the production process framework of the embodiment belongs to the TMCP technology, and through reasonable component design, Cr, Mo, Nb, Ti micro-alloys are added, and in combination with the process means of controlled rolling and controlled rolling cooling, particularly, under the condition that the content of the refractory element Mo is low and the refractory elements such as V, W and rare earth elements are not added in the smelting process and the refining process, the cooling, rolling temperature, reduction and the whole means of controlled cooling in the rolling process are controlled, and the heat treatment processes such as tempering, normalizing, quenching and tempering are not needed, the manufacturing of 460MPa steel plates of 60mm to 100mm can be realized by using a continuous casting billet of 250mm to 320mm, that is, the normal temperature yield strength ReH of the steel plates is not less than 460MPa, and the obtained steel plates have high strength, low yield ratio, excellent anti-seismic performance, low temperature toughness, lamellar tearing resistance and excellent fire resistance, specifically, the tensile strength of the steel plates is not less than 570MPa, the elongation is more than or equal to 20 percent, the yield ratio is less than or equal to 0.80, the low-temperature impact energy at minus 40 ℃ is more than or equal to 150J, the shrinkage of the end face in the Z direction is more than or equal to 35 percent, the cold bending property is 180 degrees, d =2a is qualified, the appearance is crack-free (wherein d is the diameter of a bending core, and a is the thickness of a sample), and the yield strength after heat preservation for 3 hours at 600 ℃ is more than 307MPa, so the alloy cost of the steel plate is reduced, the production process is simplified, the production period is shortened, and the production efficiency is improved.

Preferably, the smelting process is carried out in a converter, and a top-bottom combined blowing process is adopted in the converter smelting process; the refining process is carried out in an LF furnace and an RH furnace in sequence, soft blowing is carried out for more than 20min after degassing of the RH refining process, and the vacuum treatment time is more than 15 min. Therefore, the method is beneficial to improving the purity of the molten steel and reducing impurities.

Preferably, in the continuous casting process, rare gas (such as argon) is used for protection in the whole pouring process, and the liquid level of the tundish is controlled to be stable, so that impurities are further reduced, and the purity is improved. In addition, the continuous casting slabs are stacked for slow cooling treatment for 48 hours, and then unstacked.

Preferably, in the controlled rolling procedure, a spray water tank is arranged at the outlet of the roughing mill, and the continuous casting billet is rolled into an intermediate billet by the roughing mill for N times, wherein N is more than or equal to 6 and is a positive integer; wherein, the step of carrying out water cooling for 1-2 times during the process of rolling the continuous casting blank into the intermediate blank comprises the following steps: and in 1-2 odd-numbered passes in the previous N-1 pass, such as the 3 rd pass or the 3 rd pass and the 5 th pass, performing water cooling when the blank passes through the roughing mill and enters a spray water tank.

Preferably, in the controlled rolling process, in the process of roughly rolling the continuous casting blank into an intermediate blank, widening rolling and extension rolling are carried out on the blank; in the process of finish rolling the intermediate billet into a steel plate, only elongation rolling is performed on the billet, and the number of finish rolling passes is even. By adopting even-number pass finish rolling, the tail part of the steel plate is firstly subjected to water cooling for controlling a cooling process, so that the plate shape can be further improved, and the head and tail warpage is reduced.

Preferably, in the controlled cooling process, the speed of the roller way is controlled to be 0.2-0.5 m/s during each water cooling, and the steel plate is cooled by adopting the water pressure of 1.5 bar. Therefore, the method can not only ensure faster production rhythm, but also meet the requirement of cooling rate.

In addition, straightening was followed by stacking annealing for 48 hours, followed by unstacking and cutting finishing.

Compared with the prior art, the invention has the beneficial effects that: through reasonable component design and combined with technological means in controlled rolling and controlled rolling cooling, the manufacturing of 60-100 mm 460MPa earthquake-resistant steel plates can be realized by using 250-320 mm continuous casting billets without adding V, W and rare earth elements and other refractory elements and without tempering, normalizing, quenching and tempering, and the obtained steel plates have high strength, low yield ratio, earthquake resistance, low-temperature toughness, lamellar tearing resistance and excellent refractory performance.

The following provides 2 examples of the present invention to further illustrate the technical solution of the present invention. Of course, these 2 embodiments are only some, but not all, of the many variations that may be included in this embodiment.

Example 1

The steel plate comprises the following chemical components in percentage by mass: 0.070% of C, 0.25% of Si, 1.50% of Mn, 0.010% of P, 0.001% of S, 0.38% of Cr, 0.03% of Al, 0.030% of Nb, 0.015% of Ti, 0.26% of Mo and the balance of Fe and inevitable impurities.

The production process of the steel plate is as follows:

(1) sequentially carrying out KR molten iron desulphurization, converter smelting, LF refining and RH refining, wherein the converter smelting is carried out in a 180-ton converter and adopts a top-bottom combined blowing process, degassing in an RH refining process is carried out, then soft blowing is carried out for 22min, and the vacuum treatment time is 16 min;

(2) continuously casting RH refined steel into a continuous casting billet with the thickness of 320mm, the thickness of 2090mm and the thickness of 2769mm, wherein the temperature of a tundish is 1534-1549 ℃, the drawing speed of a continuous casting machine is 0.65m/s, and then stacking and slowly cooling the continuous casting billet for 48 hours to unstack;

(3) heating the continuous casting slab to 1200 ℃, wherein the heating time is 288-320 min;

(4) firstly, roughly rolling a continuous casting blank into an intermediate blank with the thickness of 150mm in multiple passes according to widening rolling and extension rolling modes; the initial rolling temperature is 1078 ℃, the final rolling temperature is 1050 ℃, and the reduction of each pass is not less than 25 mm; and the outlet of the roughing mill is provided with a spray water tank, and water cooling is respectively carried out when the 1 st rough rolling and the 3 rd rough rolling are finished (namely when the blank passes through the roughing mill and enters the spray water tank);

after the rough rolling stage is finished and before the finish rolling stage is started, carrying out water cooling on the intermediate blank obtained by rough rolling for 2 times, and then carrying out finish rolling on the intermediate blank by an even number of times of more than 6 times in an extension rolling mode to obtain a steel plate with the thickness of 60mm multiplied by 2872mm multiplied by 10746mm, wherein the initial rolling temperature is 820 ℃, the final rolling temperature is 792 ℃, and the reduction of the finish rolling of the last three times is not more than 6 mm;

(5) after the steel plate finally leaves from the finishing mill, the steel plate firstly moves forwards on a cooling roller way at the speed of 0.5m/s, cooling water collecting pipes on the upper side and the lower side of the cooling roller way are started to carry out the 1 st pass water cooling during the forward movement, the water pressure is 1.5bar, and the cooling rate is controlled to be 3 ℃/s-8 ℃/s; after finishing, the steel plate swings and air-cools for 60 s; then, the steel plate is returned backwards on a cooling roller way, the speed of the roller way is 0.5m/s, the cooling water header is started to carry out the 2 nd-pass water cooling in the period, the water pressure is 1.5bar, the cooling rate is maintained to be controlled at 3 ℃/s-8 ℃/s, and the steel plate is finally cooled to 267 ℃;

(6) straightening the cooled steel plate by using a 9-roller hydraulic straightening machine to reduce the residual stress inside and on the surface of the steel plate; stacking, slowly cooling for 48 hours, unstacking, cutting and finishing to obtain the finished steel plate.

Sampling detection is carried out on the steel plate finished product of the embodiment: (1) the metallographic structure detection result is shown in fig. 1, and the structure is a bainite structure; (2) the actual measured thickness of the steel plate is 60.10 mm; (3) the normal-temperature yield strength ReH is 527.57MPa, the tensile strength Rm is 692.83MPa, the elongation is 23.10 percent, and the yield ratio is 0.76; (4) the-40 ℃ low-temperature impact energy of the three samples is 219.62J, 199.62J and 203.33J respectively, and the Z-direction end face shrinkage rates of the three samples are 65.5%, 69.0% and 70.1% respectively; (5) d =2a is qualified when the cold bending performance is 180 degrees, and the appearance is free from cracks (wherein d is the bending core diameter, and a is the thickness of the sample); the yield strength of the product is 388.71MPa after the product is kept at 600 ℃ for 3 hours.

Therefore, the steel plate meets the standard of 460MPa anti-seismic and fireproof steel, the yield ratio is low so as to meet the anti-seismic requirement, the low-temperature toughness is excellent, the high-temperature fireproof performance meets the requirement of GB/T28415-.

Example 2

The steel plate comprises the following chemical components in percentage by mass: 0.075% of C, 0.25% of Si, 1.49% of Mn, 0.009% of P, 0.001% of S, 0.38% of Cr, 0.03% of Al, 0.031% of Nb, 0.015% of Ti, 0.26% of Mo, and the balance of Fe and inevitable impurities.

The production process of the steel plate is as follows:

(1) sequentially carrying out KR molten iron desulphurization, converter smelting, LF refining and RH refining, wherein the converter smelting is carried out in a 180-ton converter and adopts a top-bottom combined blowing process, degassing in an RH refining process is carried out, then soft blowing is carried out for 22min, and the vacuum treatment time is 17 min;

(2) continuously casting RH refined steel into a continuous casting blank with the thickness of 320mm, the thickness of 2090mm, the thickness of 4625mm, the temperature of a tundish at 1534-1549 ℃, the drawing speed of a continuous casting machine at 0.65m/s, and then stacking and slowly cooling the continuous casting blank for 48 hours to unstack;

(4) firstly, roughly rolling a continuous casting blank into an intermediate blank with the thickness of 170mm in multiple passes according to widening rolling and extension rolling modes; the initial rolling temperature is 1081 ℃, the final rolling temperature is 1048 ℃, and the reduction of each pass is not less than 25 mm; and the outlet of the roughing mill is provided with a spray water tank, and water cooling is respectively carried out when the 1 st rough rolling and the 3 rd rough rolling are finished (namely when the blank passes through the roughing mill and enters the spray water tank);

after the rough rolling stage is finished and before the finish rolling stage is started, carrying out water cooling on the intermediate blank obtained by rough rolling for 2 times, and then carrying out finish rolling on the intermediate blank by an even number of times of more than 6 times in an extension rolling mode to obtain a steel plate with the thickness of 100mm multiplied by 2857mm multiplied by 10545mm, wherein the initial rolling temperature is 810 ℃, the final rolling temperature is 795 ℃, and the reduction of the finish rolling of the last three times is not more than 6 mm;

(5) after the steel plate finally leaves from the finishing mill, the steel plate firstly moves forwards on a cooling roller way at the speed of 0.3m/s, cooling water collecting pipes on the upper side and the lower side of the cooling roller way are started to carry out the 1 st pass water cooling during the forward movement, the water pressure is 1.5bar, and the cooling rate is controlled to be 3 ℃/s-8 ℃/s; after finishing, the steel plate swings and is air-cooled for 80 s; then, the steel plate is returned backwards on the cooling roller way, the speed of the roller way is 0.3m/s, the cooling water header pipe is also started to carry out the 2 nd-pass water cooling in the period, the water pressure is 1.5bar, and the cooling rate is maintained to be controlled at 3 ℃/s-8 ℃/s; after finishing, the steel plate swings and air-cools for 60 s; then, moving the steel plate on a cooling roller way forward again, wherein the speed of the roller way is 0.3m/s, the cooling water header pipe is started to carry out 3 rd-pass water cooling in the period, the water pressure is 1.5bar, and the cooling rate is maintained to be controlled at 3 ℃/s-8 ℃/s, so that the steel plate is finally cooled to 229 ℃;

Sampling detection is carried out on the steel plate finished product of the embodiment: (1) the metallographic structure detection result is shown in fig. 2, and the structure is a bainite structure; (2) the actual measured thickness of the steel plate is 100.12 mm; (3) the normal-temperature yield strength ReH is 498.94MPa, the tensile strength Rm is 659.43MPa, the elongation is 23.47 percent, and the yield ratio is 0.76; (4) the-40 ℃ low-temperature impact work of the three samples is 214.17J, 217.35J and 233.08J respectively, and the Z-direction end face shrinkage rates of the three samples are 61.4%, 64.0% and 59.1% respectively; (5) d =2a is qualified when the cold bending performance is 180 degrees, and the appearance is free from cracks (wherein d is the diameter of a bending core, and a is the thickness of a sample); the yield strength of the product is 368.32MPa after the product is kept at 600 ℃ for 3 hours.

Claims

1. A production method of a 460 MPa-level shock-resistant fire-resistant super-thick steel plate is characterized by comprising the following steps:

(2) continuously casting the molten steel obtained in the step 1 into a continuous casting blank with the thickness of 220 mm-320 mm, and stacking the continuous casting blank for slow cooling; the temperature of the tundish during continuous casting is 1534-1549 ℃, and the casting speed of the continuous casting machine is 0.6-0.8 m/s; the chemical components of the obtained continuous casting slab comprise the following components in percentage by mass: 0.06-0.09% of C, 0.20-0.30% of Si, 1.45-1.55% of Mn, 0.30-0.45% of Cr, 0.020-0.050% of Al, 0.025-0.035% of Nb, 0.20-0.30% of Mo, 0.010-0.020% of Ti, and the balance of iron and inevitable impurities;

(5) carrying out 2-3 times of water cooling on the rolled steel plate, and swinging and air-cooling for 60-90 s between two adjacent times of water cooling, and finally cooling the steel plate to 250-300 ℃; wherein the cooling rate during each water cooling is controlled to be 3-8 ℃/s;

(6) and (3) straightening, stacking, slow cooling, cutting and finishing the steel plate obtained in the step (5) to obtain a steel plate finished product, wherein d =2a when the cold bending property of the obtained steel plate is 180 degrees, and the appearance of the steel plate is free of cracks, wherein d is the diameter of a bending core, and a is the thickness of a sample.

2. The production method of 460MPa grade earthquake-resistant and fire-resistant super-thick steel plate according to claim 1, wherein V, W and rare earth elements are not added in step (1).

3. The production method of the 460 MPa-grade earthquake-resistant and fire-resistant super-thick steel plate according to claim 1, wherein the step (1) is as follows: molten iron desulphurization, converter smelting, LF and RH refining are adopted for molten steel smelting, and P in the finally obtained molten steel is controlled to be less than 0.013 percent and S is controlled to be less than 0.003 percent in percentage by mass; wherein, the converter smelting process adopts a top-bottom combined blowing process, soft blowing is carried out for more than 20min after degassing of the RH refining process, and the vacuum treatment time is more than 15 min.

4. The production method of 460MPa grade earthquake-resistant and fire-resistant super-thick steel plate according to claim 1, wherein the stacking of step (2) is unstacked after 48 hours of slow cooling treatment time; and/or unstacking the stacks in the step (6) after 48 hours of stack slow cooling treatment.

5. The production method of the 460 MPa-level anti-seismic and fire-resistant super-thick steel plate according to claim 1, wherein in the step (4), a spray water tank is arranged at an outlet of a roughing mill, the continuous casting billet is rolled into an intermediate billet by the roughing mill for N times, wherein N is a positive integer not less than 6;

6. The production method of 460 MPa-grade earthquake-resistant and fire-resistant super-thick steel plate according to claim 1, wherein in the step (4), in the process of roughly rolling the continuous casting slab into the intermediate slab, the slab is subjected to widening rolling and extension rolling; in the process of finish rolling the intermediate billet into a steel plate, only elongation rolling is performed on the billet, and the number of finish rolling passes is even.

7. The production method of the 460 MPa-grade earthquake-resistant and fire-resistant super-thick steel plate according to claim 1, wherein in the step (5), the speed of the roller way is controlled to be 0.2-0.5 m/s during each water cooling, and the steel plate is cooled by adopting a water pressure of 1.5 bar.

8. The production method of the 460 MPa-level earthquake-resistant and fire-resistant super-thick steel plate according to claim 1, wherein the tensile strength of the obtained steel plate is greater than or equal to 570MPa, the elongation is greater than or equal to 20%, and the yield ratio is less than or equal to 0.80.

9. The production method of the 460 MPa-level earthquake-resistant and fire-resistant super-thick steel plate according to claim 1, wherein the-40 ℃ low-temperature impact energy of the obtained steel plate is not less than 150J, and the Z-direction end face shrinkage is not less than 35%; the yield strength of the steel plate is more than 307MPa after the steel plate is subjected to heat preservation for 3 hours at 600 ℃.

10. A460 MPa-grade anti-seismic fire-resistant super-thick steel plate is characterized by being prepared by the production method of any one of claims 1 to 9.