CN111876691A - Super-thick high-toughness weather-resistant bridge steel plate and production method thereof - Google Patents
Super-thick high-toughness weather-resistant bridge steel plate and production method thereof Download PDFInfo
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- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
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- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
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- C21C7/064—Dephosphorising; Desulfurising
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- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
Abstract
The invention discloses an ultra-thick high-toughness weather-resistant bridge steel plate and a production method thereof, wherein the steel plate comprises the following elements in percentage by weight: c: 0.03 to 0.11%, Mn: 0.3 to 1.1%, Si: 0.10-0.50%, P: 0.020-0.030%, S is less than or equal to 0.001%, Cr: 0.4-0.7%, Ni: 0.3-0.6%, Cu: 0.2-0.5%, Ca is more than or equal to 0.0015%, Als: 0.010-0.045%, N: 0.0020-0.0050%, and the balance of Fe and inevitable impurity elements; the super-thick high-toughness weather-resistant bridge steel plate prepared by the invention has the thickness of more than or equal to 60mm, the width of more than or equal to 3000mm, the yield strength of more than or equal to 360MPa at normal temperature, the tensile strength of more than or equal to 510MPa, the elongation of more than or equal to 22 percent, the transverse and longitudinal impact energy of more than or equal to 250J at minus 40 ℃, the fiber rate of an impact fracture of more than or equal to 90 percent, and the super-thick high-toughness weather-resistant bridge steel plate has the advantages of high strength, high toughness, excellent welding performance and good.
Description
Technical Field
The invention relates to the technical field of manufacturing of super-wide weather-resistant bridge steel plates, in particular to a super-thick high-toughness weather-resistant bridge steel plate and a production method thereof.
Background
The prosperous development of the economic society pushes the pace of infrastructure construction, bridges also step into the rapid development stage as important components, and with the optimization of bridge design and the deepened development of bridge steel, the large-scale, large-span and high-strength large-scale steel bridge construction becomes the mainstream development trend, which puts higher requirements on the comprehensive performance of the bridge steel, especially in the environments of rivers, gulf-crossing roads, railway dual-purpose steel bridges and humid and hot ocean atmosphere distributed in coastal areas, SO2High content of SO2And Cl－Coexist and,The reaction becomes a normal state, great corrosivity is caused to the bridge steel, and the large-scale steel bridge in the environment not only requires that the bridge steel has high strength, toughness, strong shock resistance and weldability, but also requires that the bridge steel has good atmospheric corrosion resistance.
Meanwhile, with the continuous improvement of the construction of highway networks in China, the width of bridge floors of large bridges spanning rivers, gorges and valleys is continuously increased, the quantity of super-long super-wide and thick steel plates selected for the processing and construction of bridge steel box girder structures is continuously increased, but higher requirements on the performance of the steel plates are provided, high requirements on the production of medium and thick plate enterprises are provided, the production difficulty is increased, the product percent of pass is lower, and particularly the longitudinal impact power of the super-thick steel plate of which the thickness is more than or equal to 60mm cannot meet the standard requirements.
Therefore, the invention provides the super-thick high-toughness weather-resistant bridge steel plate and the production method thereof aiming at the problems, and the performance requirements of the super-thick weather-resistant bridge steel plate with the width of more than or equal to 3000mm and the thickness of more than or equal to 60mm are met.
Disclosure of Invention
The invention aims to provide an ultra-thick high-toughness weather-resistant bridge steel plate and a production method thereof, wherein the yield strength of the steel plate at normal temperature is more than or equal to 360MPa, the tensile strength is more than or equal to 510MPa, the elongation is more than or equal to 22 percent, the transverse and longitudinal impact energy at minus 40 ℃ is more than or equal to 250J, the fiber rate of an impact fracture is more than or equal to 90 percent, and the steel plate has the advantages of high strength, high toughness, excellent welding performance and good atmospheric corrosion resistance, and can meet the performance requirements of steel for weather-resistant structures such as weather.
In order to achieve the purpose, the invention provides an ultra-thick high-toughness weather-resistant bridge steel plate which comprises the following elements in percentage by weight: c: 0.03 to 0.11%, Mn: 0.3 to 1.1%, Si: 0.10-0.50%, P: 0.020-0.030%, S is less than or equal to 0.001%, Cr: 0.4-0.7%, Ni: 0.3-0.6%, Cu: 0.2-0.5%, Ca is more than or equal to 0.0015%, Als: 0.010-0.045%, N: 0.0020-0.0050%, and the balance of Fe and inevitable impurity elements.
In order to achieve the purpose, the super-thick high-toughness weather-resistant bridge steel plate further comprises the following elements in percentage by weight: nb: 0.010-0.050% and/or V: 0.010-0.060% and/or Ti: 0.010-0.030%.
In order to achieve the purpose, the components and the weight percentage content of the super-thick high-toughness weather-resistant bridge steel plate provided by the invention meet the following formula:
weather resistance index I ═ 26.01 (% Cu) +3.88 (% Ni) +1.20 (% Cr) +1.49 (% Si) +17.28 (% P) -7.29 (% Cu) (% Ni) -9.10 (% Ni) (% P) -33.39 (% Cu)2≥6.5。
The super-thick high-toughness weather-resistant bridge steel plate produced according to the components and the weight percentage content has the yield strength of more than or equal to 360MPa at normal temperature, the tensile strength of more than or equal to 510MPa, the elongation of more than or equal to 22 percent, the longitudinal impact energy of more than or equal to 250J at minus 40 ℃, and the impact fracture fiber rate of more than or equal to 90 percent; the high-strength high-toughness high-strength steel has high strength, high toughness, excellent welding performance and good atmospheric corrosion resistance, and can meet the performance requirements of the steel for weather-resistant structures such as weather-resistant bridges and the like.
Preferably, the thickness of the steel plate ranges from 60mm to 100mm, and the width of the steel plate is larger than or equal to 3000 mm.
In order to achieve the purpose, the production method of the super-thick high-toughness weather-resistant bridge steel plate comprises the following steps:
(1) smelting adopts LF + RH treatment to ensure that the S content is less than or equal to 0.001 percent, the RH treatment time is not less than 10min, calcium wires are fed into steel, and then the soft argon blowing time is ensured to be more than or equal to 8 min; ensuring that the superheat degree of molten steel is 10-25 ℃, adopting electromagnetic stirring and soft pressure in the continuous casting process, wherein the electromagnetic stirring adopts the electromagnetic stirring strength with the power frequency of 4-8 Hz and the current intensity of 400-500A in a secondary cooling section; adopting electromagnetic stirring intensity with power frequency of 3-5 Hz and current intensity of 300-400A at the solidification end;
(2) heating the continuous casting slab, and controlling the temperature of a soaking section to be 1150-1250 ℃ and the soaking time to be 45-60 minutes;
(3) rolling a steel plate by adopting a rough rolling and finish rolling two-stage rolling process, cooling the casting blank plate out of a heating furnace with water at a cooling rate lower than 10 ℃/s, reducing the temperature of the upper surface and the lower surface, waiting for more than 60s, starting to perform rough rolling, adopting low-temperature high-pressure reduction in the rough rolling stage, controlling the temperature range of the rough rolling stage to be 1040-1100 ℃, enabling rolling pass intervals to be 10-15 s, waiting for temperature after the rough rolling is completed, and ensuring the total reduction of the thickness in the finish rolling stage to be 20-40%; the initial rolling temperature of the finish rolling is not more than 880 ℃, the finish rolling temperature of the finish rolling is controlled to be 830-840 ℃, and the rolling process is not stopped;
(4) and immediately performing water cooling after the steel plate is rolled, wherein the cooling rate is 8-15 ℃/s, the final cooling temperature of water cooling is 500-600 ℃, and the steel plate is leveled and cooled to 400 ℃ in the air, and then is off-line stacked for slow cooling.
The function and control range of each component in the invention have the following characteristics:
c: c is the most effective element for improving the strength of the steel, and an austenite phase region is expanded, but the welding performance of the steel plate is greatly damaged when the carbon content is too high, when the C content is below 0.12%, the influence of the carbon equivalent of the steel on crack sensitivity is not large, when the carbon content is reduced, the steel is not decomposed into two phases of ferrite and cementite during the cooling process after high-temperature deformation, but is directly converted into various forms of ferrite, and a small amount of residual austenite is left, the toughness of bainite obtained by conversion is good, and in order to ensure that the steel plate meets the required strength requirement and does not damage the toughness and weldability of the steel, the content range of C is controlled to be 0.03-0.11%.
Mn: mn is used as a substitutional atom in steel, an austenite phase region is enlarged, the A3 temperature is reduced, pearlite is refined, the strength of low-carbon and medium-carbon pearlite steel is obviously improved, the ductility and plasticity of a steel plate are not obviously influenced while the strength is increased, and the common low-alloy steel utilizes manganese to strengthen ferrite and pearlite and improve the strength of the steel. Mn is added into steel and forms plastic MnS inclusion with S, and the steel plate is extended in the rolling process to cause the increase of the anisotropy of the steel plate. And when the Mn content exceeds 1.0%, the welding performance is reduced, and in order to obtain the best matching effect of the yield strength and the weldability of the steel, the Mn content is controlled to be 0.3-1.1%.
Si: si improves the strength of steel in a solid solution strengthening mode and is a good deoxidizer in a smelting process, but when the content of silicon in the steel is too high, the yield ratio is increased, the plasticity and the toughness of the steel are reduced, and in order to obtain a steel plate with low yield ratio, high toughness and high plasticity, the content of Si is controlled to be 0.15-0.50%.
P: p is one of the most effective alloy elements for improving the atmospheric corrosion resistance of steel, and shows better composite effect when P and Cu are jointly added. However, since the P content exceeds 0.030%, the cold brittleness of the steel increases, the low-temperature toughness of the steel decreases, and the weldability deteriorates, the P content is controlled to be in the range of 0.020 to 0.030% in the present invention.
S: s is easy to form sulfides with alloy elements in steel, is unfavorable for low-temperature toughness, is unfavorable for toughness, elongation and reduction of area of steel due to the existence of sulfide inclusions, is unfavorable for weather resistance of steel, reduces S content, reduces the level of non-metallic inclusions in steel, is favorable for ensuring impact toughness, improves Z-direction performance and improves atmospheric corrosion resistance of steel, so that the S content is controlled to be less than or equal to 0.001 percent.
Cr: cr can form a compact oxide film on the surface of steel, thereby improving the passivation capability of the steel, and when the Cr content in the steel reaches more than 0.4 percent, good atmospheric corrosion resistance can be obtained. But the Cr content is too high, the tempering brittleness tendency of the steel plate is increased, and the Cr content range is controlled to be 0.4-0.7%;
cu: can improve the strength and the toughness. Copper is the most prominent alloy element with corrosion resistance in corrosion-resistant steel, and the corrosion resistance of copper steel is improved to a different degree compared with common carbon steel in industrial atmosphere, ocean atmosphere or rural atmosphere. Therefore, the selection range of Cu is as follows: 0.20 to 0.50 percent.
Ni: can be mutually fused with iron in any proportion, improves the low-temperature toughness of steel by thinning ferrite grains, and can obviously reduce the low-temperature ductile-brittle transition temperature of the steel plate. Meanwhile, Ni also has excellent chloride ion corrosion resistance, and the content of Ni in the steel is set to be 0.3-0.6%.
Ca: the trace calcium can be used as deoxidization and desulfurization cleaning agent in the steel to improve the form of non-metal inclusion, and can be used for calcium treatment of clean steel, and said invention adopts trace calcium treatment, and can control Ca content range to be greater than or equal to 0.0015%.
Al: al is a main deoxidizing element in steel, and can fix N element, refine crystal grains and improve the toughness of the steel, and in order to ensure that the deoxidizing and the nitrogen fixing are more sufficient, the content range of the Al is controlled to be more than or equal to 0.015 percent.
N: the steel has a solid solution strengthening effect, but after rapid cooling or when the steel stays for a long time at room temperature, because micro-nitrides are precipitated, precipitation strengthening can be formed, when the content of N is too high, the low-carbon steel has an aging phenomenon, the toughness is reduced, and the fracture sensitivity is increased, so that the content of residual nitrogen in the steel is too high, the macroscopic structure is loose or air holes are caused, and the control is needed, therefore, the content range of N is controlled to be 0.002-0.005%.
Nb: nb can obviously improve the austenite recrystallization temperature of the steel, enlarge the range of a non-recrystallization region and facilitate the realization of high-temperature rolling. The niobium can also inhibit the growth of austenite grains, has remarkable fine grain strengthening and precipitation strengthening effects, can remarkably improve the yield strength and the impact toughness and reduce the ductile-brittle transition temperature of the steel by adding the niobium into the steel, but is influenced by the limit value of the content of C and the heating temperature, the excessively high Nb cannot be dissolved in a solid solution, and the welding performance is deteriorated, so the control range of the Nb addition content in the invention is 0.010-0.050%.
Ti: the strong carbonitride element of Ti, which readily bonds with O, C, N, forms very stable Ti (C, N), which only melts slowly into solid solution above 1000 ℃ and effectively blocks austenite grain growth when the billet is heated. But when the titanium is added in a large amount, the nitride of the titanium is coarsened, the low-temperature toughness is reduced, and trace titanium is very effective in improving the toughness of a welding heat affected zone.
V: the steel is easy to form carbonitride with C, N elements, the carbonitride is precipitated in the cooling process after rolling or the tempering process after rolling, the precipitation strengthening effect is generated, when the precipitation is uniform and fine, the impact toughness of the steel can be improved, but when the V content is high, the welding performance of the steel is not good, so the V content range of the invention is 0.010-0.060%.
And the above element components and their weight percentages should also satisfy the following formula: atmospheric corrosion resistance index I ═ 26.01 (% Cu) +3.88 (% Ni) +1.20 (% Cr) +1.49 (%Si)+17.28(％P)－7.29(％Cu)(％Ni) －9.10(％Ni)(％P)－33.39(％Cu)2≥6.5。
According to the technical scheme provided by the invention, the refining process is optimized, the S content is controlled, large-particle MnS inclusions are reduced, the calcium wire is fed to perform denaturation treatment on the MnS and other plastic inclusions, and then the MnS inclusions are fully floated through soft blowing, so that the adverse effect of the MnS inclusions on the atmospheric corrosion resistance of steel is prevented.
And (3) cooling the casting blank with water after the casting blank is taken out of the heating furnace, wherein the cooling rate is lower than 5 ℃/s, and after the temperature of the upper surface and the lower surface is reduced, the casting blank begins to enter rough rolling for more than 60s, so that the temperature of the upper surface and the lower surface of the casting blank is properly reduced, the size of austenite grains is reduced, the core part of the casting blank, which is transferred by rolling force in the rough rolling process, is ensured, the full recovery recrystallization behavior of the austenite grains in the casting blank is.
And in the rough rolling stage, the temperature range of the rough rolling stage is controlled to be 1040-1100 ℃ under low temperature and high pressure, the rolling pass interval is 10-15 s, the austenite is fully recovered after recrystallization, and all grains are uniform. And (3) after the rough rolling is finished, the temperature is kept, the thickness ensures that the total rolling reduction in the finish rolling stage is 20-40%, and the purpose is to solve the problem that the super-thick steel plate with the thickness of more than or equal to 60mm ensures that the transverse rolling broadening reduction of the width of the steel plate is larger, fully ensure the pass reduction of longitudinal rolling and fully refine longitudinal grains.
The total reduction amount in the finish rolling stage is 20-50%, the initial rolling temperature of finish rolling is not more than 880 ℃, and the finish rolling temperature of finish rolling is controlled to be 830-840 ℃; by controlling the rolling reduction, the austenite grains can be properly deformed, and the purpose of keeping the rolling process is to ensure the thinning accumulation of the austenite grains and ensure the uniform and fine grains in the thickness direction. And after the steel plates are cooled, stacking and slow cooling are carried out, so that the uniform release of the stress in the steel is ensured. Thereby obtaining the super-thick high-toughness weather-proof bridge steel plate with the thickness of more than or equal to 60 mm.
The super-thick high-toughness weather-resistant bridge steel plate prepared by the invention has the thickness of more than or equal to 60mm, the yield strength of more than or equal to 360MPa at normal temperature, the tensile strength of more than or equal to 510MPa, the elongation of more than or equal to 22 percent, the transverse and longitudinal impact energy of-40 ℃ of more than or equal to 250J, and the fiber rate of an impact fracture of more than or equal to 90 percent, has high strength, high toughness, excellent welding performance and good atmospheric corrosion resistance, and can meet the performance requirements of steel for weather-resistant structures such as weather-resistant.
Detailed Description
In order to better explain the technical solution of the present invention, the technical solution of the present invention is further described below with reference to specific examples, which are only exemplary to illustrate the technical solution of the present invention and do not limit the present invention in any form.
The following table 1 is a list of chemical components contained in the steel plate in each example of the invention by mass percentage;
table 2 below is a table listing the results of the primary performance tests for each of the examples of the present invention.
The invention discloses an ultra-thick high-toughness weather-resistant bridge steel plate which comprises the following elements in percentage by weight: c: 0.03 to 0.11%, Mn: 0.3 to 1.1%, Si: 0.10-0.50%, P: 0.020-0.030%, S is less than or equal to 0.001%, Cr: 0.4-0.7%, Ni: 0.3-0.6%, Cu: 0.2-0.5%, Ca is more than or equal to 0.0015%, Als: 0.010-0.045%, N: 0.0020-0.0050%, and the balance of Fe and inevitable impurity elements.
Besides the elements, the alloy also comprises the following elements in percentage by weight: nb: 0.010-0.050% and/or V: 0.010-0.060% and/or Ti: 0.010-0.030%.
The components and the weight percentage content also accord with the following formula:
weather resistance index I ═ 26.01 (% Cu) +3.88 (% Ni) +1.20 (% Cr) +1.49 (% Si) +17.28 (% P) -7.29 (% Cu) (% Ni) -9.10 (% Ni) (% P) -33.39 (% Cu)2≥6.5。
The production method of the super-thick high-toughness weather-resistant bridge steel plate comprises the following steps:
(1) smelting adopts LF + RH treatment to ensure that the S content is less than or equal to 0.001 percent, the RH treatment time is not less than 10min, calcium wires are fed into steel, and then the soft argon blowing time is ensured to be more than or equal to 8 min; the refining process is optimized, the S content is controlled, large-particle MnS inclusions are reduced, plastic inclusions such as MnS and the like are subjected to denaturation treatment by calcium feeding wires, and then the plastic inclusions are fully floated through soft blowing, so that the adverse effect of the MnS inclusions on the atmospheric corrosion resistance of steel is prevented; ensuring that the superheat degree of molten steel is 10-25 ℃, adopting electromagnetic stirring and soft pressure in the continuous casting process, wherein the electromagnetic stirring adopts the electromagnetic stirring strength with the power frequency of 4-8 Hz and the current intensity of 400-500A in the secondary cooling section; adopting electromagnetic stirring intensity with power frequency of 3-5 Hz and current intensity of 300-400A at the solidification end;
(2) heating the continuous casting slab, and controlling the temperature of a soaking section to be 1150-1250 ℃ and the soaking time to be 45-60 minutes; the heating process is set below 1250 ℃, so as to prevent austenite grains from coarsening to seriously affect the toughness, ensure enough soaking time and fully and uniformly diffuse the element segregation and the like of the steel grade;
(3) rolling a steel plate by adopting a rough rolling and finish rolling two-stage rolling process, cooling the casting blank plate out of a heating furnace by water at a cooling rate lower than 5 ℃/s, and waiting for more than 60s to start rough rolling after the temperature of the upper surface and the lower surface is reduced, so that the temperature of the upper surface and the lower surface of the casting blank is properly reduced, the size of austenite grains is reduced, the core part of the casting blank, which is transferred by rolling force in the rough rolling process, is ensured, the full recovery recrystallization behavior of the austenite grains in the casting blank is ensured, and the grains are refined; the rough rolling stage adopts low temperature and high pressure, the temperature range of the rough rolling stage is controlled to be 1040-1100 ℃, the rolling pass interval is 10-15 s, the full recovery of austenite after recrystallization is ensured, and the uniformity of each crystal grain is ensured; after rough rolling is finished, temperature is kept, the thickness ensures that the total rolling reduction in the finish rolling stage is 20-40%, and the purpose is to solve the problems that an ultra-thick steel plate with the width of more than or equal to 3000mm and the thickness of more than or equal to 60mm ensures that the transverse rolling broadening reduction of the steel plate width is larger, and the pass reduction of longitudinal rolling is fully ensured, so that longitudinal grains are fully refined; the initial rolling temperature of the finish rolling is not more than 880 ℃, the finish rolling temperature of the finish rolling is controlled to be 830-840 ℃, and the rolling process is not stopped; by controlling the rolling reduction, the austenite grains can be properly deformed, and the purpose of keeping the rolling process is to ensure the thinned accumulation of the austenite grains and the uniform and small grains in the thickness direction;
(4) and immediately carrying out water cooling after the steel plate is rolled, wherein the cooling rate is 8-15 ℃/s, the final cooling temperature of water cooling is 500-600 ℃, the steel plate is leveled and cooled to 400 ℃ in the air, and then is subjected to off-line stacking and slow cooling, so that the stress in the steel is ensured to be uniformly released, and the super-thick high-toughness weather-resistant bridge steel plate with the thickness of more than or equal to 60mm is obtained.
The super-thick high-toughness weather-resistant bridge steel plate with the thickness of more than or equal to 60mm and the manufacturing method thereof have the advantages that the yield strength of the steel plate at normal temperature is more than or equal to 360MPa, the tensile strength is more than or equal to 510MPa, the elongation is more than or equal to 22 percent, the transverse and longitudinal impact energy at minus 40 ℃ is more than or equal to 250J, the fiber rate of an impact fracture is more than or equal to 90 percent, the steel plate has high strength, high toughness, excellent welding performance and good atmospheric corrosion resistance, and can meet the performance requirements of steel for weather.
The technical solutions of the present invention are further described in detail with reference to the following specific examples, which should be understood that the following examples are only illustrative of the present invention and are not intended to limit the present invention.
TABLE 1 tabulation of chemical composition in mass percentage of steel plate in each example of the present invention
Example 1
This example illustrates how to prepare an ultra-thick high toughness weather-resistant bridge steel plate with a width of 3150mm and a thickness of 60 mm. The steel sheet of this example had the composition and the weight percentage content shown in table 1.
The production method of the super-thick high-toughness weather-resistant bridge steel plate comprises the following steps:
(1) LF and RH treatment are adopted for smelting, the RH treatment time is not less than 13min, calcium wires are fed into the steel, and then the soft argon blowing time is ensured for 10 min; ensuring that the superheat degree of the molten steel is 15 ℃, adopting electromagnetic stirring and light pressure in the continuous casting process, wherein the electromagnetic stirring adopts the electromagnetic stirring strength with the power frequency of 6Hz and the current intensity of 450A in a secondary cooling section; adopting the electromagnetic stirring intensity with the power frequency of 4Hz and the current intensity of 350A at the solidification end;
(2) the specification of the continuous casting plate blank is 300 x 2200 mm; the temperature of the soaking section of the plate blank is 1235 ℃, and the soaking time is 48 minutes;
(3) rolling a steel plate by adopting a two-stage rolling process of rough rolling and finish rolling, cooling the blank of a casting blank by water after the blank is taken out of a heating furnace at a cooling rate of 5 ℃/s, reducing the temperature of the upper surface and the lower surface, waiting for 65s, adopting low-temperature high pressure reduction in the rough rolling stage, controlling the temperature range of the rough rolling stage to be 1050-1095 ℃, the rolling pass interval to be 10s, and finishing the rough rolling until the temperature and the thickness are 100 mm; the initial rolling temperature of the finish rolling is 851 ℃, the final rolling temperature of the finish rolling is controlled to be 834 ℃, and the rolling process is not stopped;
(4) immediately carrying out water cooling after the steel plate is rolled, wherein the cooling rate is 8 ℃/s, the final cooling temperature of water cooling is 586 ℃, and the steel plate is cooled to 400 ℃ in the air after being leveled and then is subjected to off-line stacking and slow cooling; the steel plate manufactured by adopting the element component content and the processing steps has the thickness specification of 60mm × 3150mm, and the mechanical properties of the steel plate are shown in table 2.
Example 2
This example illustrates the preparation of an ultra-thick high-toughness weather-resistant bridge steel plate with a width of 3280mm and a thickness of 70 mm. The steel sheet of this example had the composition and the weight percentage content shown in table 1.
The production method of the super-thick high-toughness weather-resistant bridge steel plate comprises the following steps:
(1) LF and RH treatment are adopted for smelting, the RH treatment time is not less than 15min, calcium wires are fed into the steel, and then the soft argon blowing time is ensured for 12 min; ensuring that the superheat degree of molten steel is 25 ℃, adopting electromagnetic stirring and soft reduction in the continuous casting process, wherein the electromagnetic stirring adopts the electromagnetic stirring strength with the power frequency of 7Hz and the current intensity of 430A in a secondary cooling section; adopting the electromagnetic stirring intensity with the power frequency of 5Hz and the current intensity of 380A at the solidification end;
(2) the selected continuous casting slab is 300 x 2300 mm; the temperature of the soaking section of the plate blank is 1189 ℃, and the soaking time is 56 minutes;
(3) rolling a steel plate by adopting a rough rolling and finish rolling two-stage rolling process, cooling the casting blank plate blank out of a heating furnace at a cooling rate of 4 ℃/s, waiting for 70s after the temperature of the upper surface and the lower surface is reduced, adopting low-temperature high pressure in the rough rolling stage, controlling the temperature range of the rough rolling stage to be 1055-1100 ℃, the rolling pass interval to be 10s, and finishing the rough rolling until the temperature and the thickness are 115 mm; the initial rolling temperature of the finish rolling is 845 ℃, the final rolling temperature of the finish rolling is 835 ℃, and the rolling process is not stopped;
(4) and immediately performing water cooling after the steel plate is rolled, wherein the cooling rate is 12 ℃/s, the final cooling temperature of water cooling is 505 ℃, and the steel plate is cooled to 400 ℃ in the air after being leveled and then is subjected to off-line stacking and slow cooling. The steel plate manufactured by adopting the element component content and the processing steps has the thickness specification of 70mm 3280mm, and the mechanical properties of the steel plate are shown in table 2.
Example 3
In this example, the present invention is explained in detail by taking an example of preparing an ultra-thick high-toughness weather-resistant bridge steel plate with a width of 3080mm and a thickness of 80 mm. The steel sheet of this example had the composition and the weight percentage content shown in table 1.
The production method of the super-thick high-toughness weather-resistant bridge steel plate comprises the following steps:
(1) LF and RH treatment are adopted for smelting, the RH treatment time is not less than 19min, calcium wires are fed into the steel, and then the soft argon blowing time is ensured for 11 min; ensuring that the superheat degree of molten steel is 19 ℃, adopting electromagnetic stirring and soft pressure in the continuous casting process, wherein the electromagnetic stirring adopts the electromagnetic stirring strength with the power frequency of 8Hz and the current intensity of 470A in a secondary cooling section; adopting the electromagnetic stirring intensity with the power frequency of 3Hz and the current intensity of 320A at the solidification end;
(2) the selected continuous casting slab is 300 x 2300 mm; the temperature of the soaking section of the plate blank is 1189 ℃, and the soaking time is 56 minutes;
(3) rolling a steel plate by adopting a rough rolling and finish rolling two-stage rolling process, cooling the casting blank plate blank out of a heating furnace at a cooling rate of 4 ℃/s, waiting for 70s after the temperature of the upper surface and the lower surface is reduced, adopting low-temperature high pressure in the rough rolling stage, controlling the temperature range of the rough rolling stage to be 1055-1100 ℃, rolling pass interval to be 10s, and finishing the rough rolling until the temperature and the thickness are 120 mm; the initial rolling temperature of finish rolling is 851 ℃, the final rolling temperature of finish rolling is controlled to be 840 ℃, and the rolling process is not stopped;
(4) and immediately performing water cooling after the steel plate is rolled, wherein the cooling rate is 9 ℃/s, the final cooling temperature of the water cooling is 536 ℃, and the steel plate is cooled to 400 ℃ in the air after being leveled and then is subjected to off-line stacking and slow cooling. The steel plate manufactured by adopting the element component content and the processing steps has the thickness specification of 80mm 3280mm, and the mechanical properties of the steel plate are shown in table 2.
Example 4
This example illustrates how to prepare an ultra-thick high toughness weather-resistant bridge steel plate with a width of 3300mm and a thickness of 90 mm. The steel sheet of this example had the composition and the weight percentage content shown in table 1.
The production method of the super-thick high-toughness weather-resistant bridge steel plate comprises the following steps:
(1) LF and RH treatment are adopted for smelting, the RH treatment time is not less than 15min, calcium wires are fed into the steel, and then the soft argon blowing time is ensured for 13 min; ensuring that the superheat degree of molten steel is 12 ℃, adopting electromagnetic stirring and soft reduction in the continuous casting process, wherein the electromagnetic stirring adopts the electromagnetic stirring strength with the power frequency of 5Hz and the current intensity of 430A in a secondary cooling section; adopting the electromagnetic stirring intensity with the power frequency of 4Hz and the current intensity of 340A at the solidification end;
(2) the selected continuous casting slab is 300 x 2300 mm; the temperature of the soaking section of the plate blank is 1166 ℃, and the soaking time is 60 minutes;
(3) rolling a steel plate by adopting a rough rolling and finish rolling two-stage rolling process, cooling the casting blank plate blank out of a heating furnace at a cooling rate of 3 ℃/s, waiting for 60s after the temperature of the upper surface and the lower surface is reduced, adopting low-temperature high pressure in the rough rolling stage, controlling the temperature range of the rough rolling stage to be 1045-1100 ℃, the rolling pass interval to be 12s, and finishing the rough rolling until the temperature and the thickness are 120 mm; the initial rolling temperature of finish rolling is 847 ℃, the final rolling temperature of finish rolling is controlled to be 833 ℃, and the rolling process is not stopped;
(4) and immediately performing water cooling after the steel plate is rolled, wherein the cooling rate is 8 ℃/s, the final cooling temperature of water cooling is 562 ℃, and the steel plate is cooled to 400 ℃ in the air after being leveled and then is subjected to off-line stacking and slow cooling. The steel plate manufactured by adopting the element component content and the processing steps has the thickness specification of 90mm 3300mm, and the mechanical properties of the steel plate are shown in table 2.
Example 5
This example illustrates the preparation of an ultra-thick high toughness weather resistant bridge steel plate with a width of 3020mm and a thickness of 100 mm. The steel sheet of this example had the composition and the weight percentage content shown in table 1.
The production method of the super-thick high-toughness weather-resistant bridge steel plate comprises the following steps:
(1) LF and RH treatment are adopted for smelting, the RH treatment time is not less than 17min, calcium wires are fed into the steel, and then the soft argon blowing time is ensured for 15 min; ensuring that the superheat degree of molten steel is 18 ℃, adopting electromagnetic stirring and soft pressure in the continuous casting process, wherein the electromagnetic stirring adopts the electromagnetic stirring strength with the power frequency of 6Hz and the current intensity of 450A in a secondary cooling section; the power frequency is 3Hz and the current intensity is 300A at the solidification end.
(2) The selected continuous casting slab is 300 x 2300 mm; the temperature of the soaking section of the plate blank is 1216 ℃, and the soaking time is 49 minutes;
(3) rolling a steel plate by adopting a rough rolling and finish rolling two-stage rolling process, cooling the casting blank plate blank out of a heating furnace at a cooling rate of 4 ℃/s, waiting for 63s after the temperature of the upper surface and the lower surface is reduced, adopting low-temperature high pressure in the rough rolling stage, controlling the temperature range of the rough rolling stage to be 1051-1100 ℃, the rolling pass interval to be 11s, and finishing the rough rolling until the temperature and the thickness are 140 mm; the initial rolling temperature of the finish rolling is 840 ℃, the final rolling temperature of the finish rolling is controlled to be 835 ℃, and the rolling process is not stopped;
(4) and immediately performing water cooling after the steel plate is rolled, wherein the cooling rate is 9 ℃/s, the final cooling temperature of water cooling is 543 ℃, and the steel plate is cooled to 400 ℃ in the air after being leveled, and then is off-line stacked for slow cooling. The steel plate manufactured by adopting the element component contents and the processing steps has the thickness specification of 100 mm-3020 mm, and the mechanical properties of the steel plate are shown in table 2.
TABLE 2 Main mechanical Properties test List of the steel plates in the examples of the present invention
As can be seen from Table 2 and various examples, by adopting the super-thick high-toughness weather-resistant bridge steel plate and the production method thereof provided by the invention, the yield strength of the prepared steel plate at normal temperature is more than or equal to 360MPa, the tensile strength is more than or equal to 510MPa, the elongation is more than or equal to 22%, the transverse and longitudinal impact energy at minus 40 ℃ is more than or equal to 250J, the fiber rate of an impact fracture is more than or equal to 90%, the width is more than or equal to 3000mm, and the thickness is more than; the data in table 1 also show that the atmospheric corrosion resistance index I of the steel plate in the embodiment of the present invention is higher than 6.5 (in the industry, the atmospheric corrosion resistance index I exceeding 6.0 is a steel material with good corrosion resistance), which is higher than the requirement in the industry, and the value of the steel plate I in the embodiment 2 even reaches 7.49, which fully indicates that the steel material of the present invention has high strength, high toughness, excellent welding performance and good atmospheric corrosion resistance, and can meet the performance requirements of the steel for weather-resistant structures such as weather-resistant bridges.
Claims (6)
1. The super-thick high-toughness weather-resistant bridge steel plate is characterized by comprising the following elements in percentage by weight: c: 0.03 to 0.11%, Mn: 0.3 to 1.1%, Si: 0.10-0.50%, P: 0.020-0.030%, S is less than or equal to 0.001%, Cr: 0.4-0.7%, Ni: 0.3-0.6%, Cu: 0.2-0.5%, Ca is more than or equal to 0.0015%, Als: 0.010-0.045%, N: 0.0020-0.0050%, and the balance of Fe and inevitable impurity elements.
2. The ultra-thick high-toughness weather-resistant bridge steel plate as claimed in claim 1, wherein the steel plate further comprises the following elements in percentage by weight: nb: 0.010-0.050% and/or V: 0.010-0.060% and/or Ti: 0.010-0.030%.
3. The ultra-thick high-toughness weather-resistant bridge steel plate as claimed in claim 1, wherein: the components and the weight percentage content of the steel plate are in accordance with the following formula:
index of atmospheric corrosion resistanceI=26.01（%Cu）+3.88（%Ni）+1.20（%Cr）+1.49（%Si）+17.28（%P）－7.29（%Cu）（%Ni）－9.10（%Ni）（%P）－33.39（%Cu）2≥6.5。
4. The ultra-thick high-toughness weather-resistant bridge steel plate as claimed in claim 1, wherein: the yield strength of the steel plate at normal temperature is more than or equal to 360MPa, the tensile strength is more than or equal to 510MPa, the elongation is more than or equal to 22 percent, the longitudinal impact energy at minus 40 ℃ is more than or equal to 250J, and the fiber percentage of an impact fracture is more than or equal to 90 percent.
5. The ultra-thick high-toughness weather-resistant bridge steel plate as claimed in claim 1, wherein: the thickness range of the steel plate is 60-100 mm, and the width is larger than or equal to 3000 mm.
6. The method for producing the ultra-thick high-toughness weather-resistant bridge steel plate as claimed in any one of claims 1 to 5, which is characterized by comprising the following steps of:
(1) smelting adopts LF + RH treatment to ensure that the S content is less than or equal to 0.001 percent, the RH treatment time is not less than 10min, calcium wires are fed into steel, and then the soft argon blowing time is ensured to be more than or equal to 8 min; ensuring that the superheat degree of molten steel is 10-25 ℃, adopting electromagnetic stirring and soft pressure in the continuous casting process, wherein the electromagnetic stirring adopts the electromagnetic stirring strength with the power frequency of 4-8 Hz and the current intensity of 400-500A in the secondary cooling section; adopting electromagnetic stirring intensity with power frequency of 3-5 Hz and current intensity of 300-400A at the solidification end;
(2) heating the continuous casting slab, and controlling the temperature of a soaking section to be 1150-1250 ℃ and the soaking time to be 45-60 minutes;
(3) rolling a steel plate by adopting a rough rolling and finish rolling two-stage rolling process, cooling the casting blank plate out of a heating furnace with water at a cooling rate lower than 10 ℃/s, reducing the temperature of the upper surface and the lower surface, waiting for more than 60s, starting to perform rough rolling, adopting low-temperature high pressure reduction in the rough rolling stage, controlling the temperature range of the rough rolling stage to be 1040-1100 ℃, enabling rolling pass intervals to be 10-15 s, waiting for temperature after the rough rolling is completed, and ensuring the total reduction of the thickness in the finish rolling stage to be 20-40%; the initial rolling temperature of the finish rolling is not more than 880 ℃, the finish rolling temperature of the finish rolling is controlled to be 830-840 ℃, and the rolling process is not stopped;
(4) and immediately performing water cooling after the steel plate is rolled, wherein the cooling rate is 8-15 ℃/s, the final cooling temperature of water cooling is 500-600 ℃, and the steel plate is leveled and cooled to 400 ℃ in the air and then is off-line stacked for slow cooling.
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| CN113667888A (en) * | 2021-07-14 | 2021-11-19 | 武汉钢铁有限公司 | 690 MPa-grade low-silicon corrosion-resistant bridge steel and preparation method thereof |
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| CN113817948A (en) * | 2021-08-16 | 2021-12-21 | 包头钢铁（集团）有限责任公司 | Production method of high-toughness bridge steel with yield strength of 345MPa |
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| CN114381663A (en) * | 2021-12-16 | 2022-04-22 | 南阳汉冶特钢有限公司 | 100 mm-thick HPS420WZ35 weather-resistant bridge plate and production method for ensuring performance thereof |
| CN114752724A (en) * | 2022-05-25 | 2022-07-15 | 宝武集团鄂城钢铁有限公司 | 750 MPa-grade bridge steel with excellent low-internal-stress welding performance and preparation method thereof |
| CN114892090A (en) * | 2022-05-25 | 2022-08-12 | 湖南华菱湘潭钢铁有限公司 | Production method of Q550-grade high-corrosion-resistance high-strength offshore structure steel |
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