CN116555667A - Weather-resistant bridge steel plate Q345qDNH with high impact toughness and manufacturing method - Google Patents

Weather-resistant bridge steel plate Q345qDNH with high impact toughness and manufacturing method Download PDF

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Publication number
CN116555667A
CN116555667A CN202310549618.2A CN202310549618A CN116555667A CN 116555667 A CN116555667 A CN 116555667A CN 202310549618 A CN202310549618 A CN 202310549618A CN 116555667 A CN116555667 A CN 116555667A
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China
Prior art keywords
weight percent
weather
q345qdnh
high impact
equal
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Inventor
李宗强
叶姜
朱鹏宇
肖娟
李显
廖耀俊
杨柳
袁勤攀
何涛
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Liuzhou Iron and Steel Co Ltd
Guangxi Liuzhou Iron and Steel Group Co Ltd
Guangxi Liugang Huachuang Technology R&D Co Ltd
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Liuzhou Iron and Steel Co Ltd
Guangxi Liuzhou Iron and Steel Group Co Ltd
Guangxi Liugang Huachuang Technology R&D Co Ltd
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Priority to CN202310549618.2A priority Critical patent/CN116555667A/en
Publication of CN116555667A publication Critical patent/CN116555667A/en
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
    • B21B1/24—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
    • B21B1/26—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process by hot-rolling, e.g. Steckel hot mill
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • 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
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • 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
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • 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
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • 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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

The invention providesThe weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following chemical components in percentage by weight: c:0.05 to 0.09 weight percent, si:0.15 to 0.35 weight percent, mn:1.10 to 1.30 weight percent, P is less than or equal to 0.020 weight percent, S is less than or equal to 0.008 weight percent, nb:0.030 to 0.045wt percent, ti:0.010 to 0.020wt%, cr:0.40 to 0.55 weight percent, ni:0.30 to 0.40 weight percent, cu:0.25 to 0.35 weight percent, alt:0.020 to 0.040 weight percent, and N is less than or equal to 0.005 weight percent; the balance of Fe and unavoidable trace elements; the invention obtains the yield strength R of the weather-resistant bridge steel plate Q345qDNH product with high impact toughness through reasonable design of components and production process eL More than or equal to 400MPa, tensile strength Rm more than or equal to 500MPa, elongation A more than or equal to 26 percent, and low-temperature impact energy at minus 20 ℃ more than or equal to 270J.

Description

Weather-resistant bridge steel plate Q345qDNH with high impact toughness and manufacturing method
Technical Field
The invention relates to the field of steel production and manufacturing, in particular to a weather-proof bridge steel plate Q345qDNH and a manufacturing method thereof, and especially relates to a weather-proof bridge steel plate Q345qDNH with high impact toughness and a manufacturing method thereof.
Background
At present, with the development of social economy in China, the national infrastructure is gradually perfected, and the quality requirements on the large-span, high-strength and light-weight bridge steel for the fields of highways, railways and oceans are higher and higher. The weather-resistant bridge steel plate Q345qDNH is specially used for constructing steel plates of highway or railway bridges, and is required to have higher strength and toughness, bear the load and impact of rolling stocks, and have good fatigue resistance, certain low-temperature toughness and atmospheric corrosion resistance.
In summary, the following problems exist in the prior art: the impact toughness of the existing weather-resistant bridge steel plate Q345qDNH can not meet the construction requirements of the constructed highway or railway bridge.
Disclosure of Invention
The invention provides a weather-proof bridge steel plate Q345qDNH with high impact toughness and a manufacturing method thereof, which are used for solving the problem that the impact toughness of the existing weather-proof bridge steel plate Q345qDNH cannot meet the construction requirement of a constructed highway or railway bridge, so that the weather-proof bridge steel plate Q345qDNH with stable mechanical performance and high impact toughness is obtained.
Therefore, the invention provides a weather-resistant bridge steel plate Q345qDNH and a manufacturing method thereof, in particular to a weather-resistant bridge steel plate Q345qDNH with high impact toughness and a manufacturing method thereof, wherein the weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following chemical components in percentage by weight: c:0.05 to 0.09 weight percent, si:0.15 to 0.35 weight percent, mn:1.10 to 1.30 weight percent, P is less than or equal to 0.020 weight percent, S is less than or equal to 0.008 weight percent, nb:0.030 to 0.045wt percent, ti:0.010 to 0.020wt%, cr:0.40 to 0.55 weight percent, ni:0.30 to 0.40 weight percent, cu:0.25 to 0.35 weight percent, alt:0.020 to 0.040 weight percent, and N is less than or equal to 0.005 weight percent; the balance of Fe and unavoidable trace elements; the yield strength R of the weather-resistant bridge steel plate Q345qDNH product with high impact toughness eL More than or equal to 400MPa, tensile strength Rm more than or equal to 500MPa, elongation A more than or equal to 26 percent, and low-temperature impact energy at minus 20 ℃ more than or equal to 270J.
The manufacturing method of the weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following sequentially performed process steps:
blast furnace molten iron smelting, molten iron desulfurization pretreatment, converter molten steel smelting, LF molten steel refining (ladle refining) treatment, RH molten steel refining (molten steel vacuum circulation degassing refining) treatment, slab continuous casting, hot plate billet heating, descaling, rough rolling, finish rolling, straightening, sampling, steel plate II-level flaw detection and marking warehousing;
wherein the soaking temperature of the casting blank heating furnace is controlled to be 1160-1240 ℃.
Further, the heating time of the casting blank in the furnace is more than or equal to 210min, and the soaking time is more than or equal to 35min.
Further, finish rolling was set to 8-pass continuous rolling.
Further, the weather-resistant bridge steel plate Q345qDNH with high impact toughness does not use rolling mill cooling water and post-rolling cold control water after rolling.
Further, when the thickness of the finished product of the weather-resistant bridge steel plate Q345qDNH with high impact toughness is delta, delta is more than or equal to 8 and less than or equal to 10mm, the finish rolling start temperature is 1030+/-30 ℃, and the finish rolling temperature is 850+/-30 ℃.
Further, when the thickness of the finished product of the weather-resistant bridge steel plate Q345qDNH with high impact toughness is delta, delta is more than 10mm and less than or equal to 16mm, the finish rolling start temperature is 960+/-30 ℃, and the finish rolling temperature is 850+/-30 ℃.
Further, when the thickness of the finished product of the weather-resistant bridge steel plate Q345qDNH with high impact toughness is delta, delta is 16mm less than or equal to 20mm, the finish rolling start temperature is 920+/-30 ℃, and the finish rolling temperature is 840+/-30 ℃.
Further, when the thickness of the finished product of the weather-resistant bridge steel plate Q345qDNH with high impact toughness is delta, delta is more than 20mm and less than or equal to 30mm, the finish rolling start temperature is 890+/-30 ℃, and the finish rolling temperature is 820+/-30 ℃.
Further, smelting the converter molten steel: the molten iron requirement S is less than or equal to 0.010 weight percent, the whole process of bottom blowing argon is adopted in the smelting process, and the converter end point control C:0.04 to 0.06 weight percent, and P is less than or equal to 0.015 weight percent.
Further, the thickness delta of the finished product of the weather-resistant bridge steel plate Q345qDNH with high impact toughness is 10mm, and the chemical components in percentage by weight are as follows: c:0.071wt%, si:0.25wt%, mn:1.22wt%, P:0.014wt%, S:0.003wt%, nb:0.040wt%, ti:0.019wt%, cr:0.45wt%, ni:0.33wt%, cu:0.28wt%, alt:0.026wt%, N:0.0045wt% of Fe and the balanceUnavoidable trace elements, the soaking temperature of a casting blank heating furnace is 1218 ℃, the heating time of the casting blank in the furnace is 263min, the soaking time is 43min, the finish rolling starting temperature is 1023 ℃, the finish rolling finishing temperature is 834 ℃, and the yield strength R of the product is obtained eL 452MPa, a tensile strength Rm of 596MPa, an elongation A of 27.3% and a low-temperature impact energy of 273J at-20 ℃.
Further, the thickness delta of the finished product of the weather-resistant bridge steel plate Q345qDNH with high impact toughness is 16mm, and the chemical components in percentage by weight are as follows: c:0.064wt%, si:0.25wt%, mn:1.18wt%, P:0.013wt%, S:0.004wt%, nb:0.037wt%, ti:0.017wt%, cr:0.45wt%, ni:0.32wt%, cu:0.27wt%, alt:0.029wt%, N:0.0038wt%, and the balance of Fe and unavoidable trace elements, wherein the soaking temperature of a casting blank heating furnace is 1211 ℃, the heating time of the casting blank in the furnace is 255min, the soaking time is 46min, the finish rolling start temperature is 972 ℃, the finish rolling temperature is 841 ℃, and the yield strength R of the product is obtained eL The tensile strength Rm is 548MPa, the elongation A is 29.8%, and the low-temperature impact energy at-20 ℃ is 327J.
Further, the thickness delta of the finished product of the weather-resistant bridge steel plate Q345qDNH with high impact toughness is 20mm, and the chemical components in percentage by weight are as follows: c:0.080wt%, si:0.23wt%, mn:1.20wt%, P:0.013wt%, S:0.001wt%, nb:0.034wt%, ti:0.015wt%, cr:0.46wt%, ni:0.32wt%, cu:0.27wt%, alt:0.031wt%, N:0.0037wt%, and the balance of Fe and unavoidable trace elements, wherein the soaking temperature of a casting blank heating furnace is 1213 ℃, the heating time of the casting blank in the furnace is 260min, the soaking time is 42min, the finish rolling start temperature is 912 ℃, the finish rolling temperature is 839 ℃, and the yield strength R of the product is obtained eL The tensile strength Rm is 536MPa, the elongation A is 29.5%, and the low-temperature impact energy at-20 ℃ is 351J.
The invention also provides a weather-resistant bridge steel plate Q345qDNH with high impact toughness, which is prepared by the method according to any one of the steps, wherein the weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following chemical components in percentage by weight: c:0.05 to 0.09 weight percent, si:0.15 to 0.35 weight percent, mn:1.10 to 1.30 weight percent, P is less than or equal to 0.020 weight percent, S is less than or equal to 0.008 weight percent, nb:0.030 to 0.045wt percent, ti:0.010 to 0.020wt%, cr:0.40 to 0.55 weight percent, ni:0.30 to 0.40 weight percent, cu:0.25 to 0.35 weight percent, alt:0.020 to 0.040 weight percent, and N is less than or equal to 0.005 weight percent; the balance of Fe and unavoidable trace elements.
The invention provides a weather-proof bridge steel plate Q345qDNH with high impact toughness and a manufacturing method thereof through reasonable design components and a production process, wherein the weather-proof bridge steel plate Q345qDNH with high impact toughness comprises the following chemical components in percentage by weight: c:0.05 to 0.09 weight percent, si:0.15 to 0.35 weight percent, mn:1.10 to 1.30 weight percent, P is less than or equal to 0.020 weight percent, S is less than or equal to 0.008 weight percent, nb:0.030 to 0.045wt percent, ti:0.010 to 0.020wt%, cr:0.40 to 0.55 weight percent, ni:0.30 to 0.40 weight percent, cu:0.25 to 0.35 weight percent, alt:0.020 to 0.040 weight percent, and N is less than or equal to 0.005 weight percent; the balance of Fe and unavoidable trace elements;
the manufacturing method of the weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following sequentially performed process steps:
blast furnace molten iron smelting, molten iron desulfurization pretreatment, converter molten steel smelting, LF molten steel refining, RH molten steel refining, slab continuous casting, hot plate blank heating, descaling, rough rolling, finish rolling, straightening, sampling, steel plate II-level flaw detection and marking warehousing;
wherein the soaking temperature of the casting blank heating furnace is controlled to be 1160-1240 ℃.
According to the invention, cu, ni and Cr elements are added into steel to ensure weather resistance, a proper amount of Nb+Ti microalloy is added into the steel through the design of low carbon components in the steel, the N content in the steel is strictly controlled, a reasonable smelting-continuous casting-rolling process is formulated, stable production of the product is realized, and the weather-resistant bridge steel plate Q345qDNH with stable mechanical property and high impact toughness is obtained. The yield strength R of the weather-resistant bridge steel plate Q345qDNH product with high impact toughness eL More than or equal to 400MPa, tensile strength Rm more than or equal to 500MPa, elongation A more than or equal to 26 percent, and low-temperature impact energy at minus 20 ℃ more than or equal to 270J.
Drawings
FIG. 1 is a photograph showing a metallographic structure of example 1 of the present invention;
FIG. 2 is a photograph showing a metallographic structure of example 4 of the present invention.
Detailed Description
The present invention will now be described for a clearer understanding of technical features, objects, and effects of the present invention.
The invention provides a weather-resistant bridge steel plate Q345qDNH with high impact toughness and a manufacturing method thereof, and the yield strength R of a researched product eL More than or equal to 400MPa, tensile strength Rm more than or equal to 500MPa, elongation A more than or equal to 26 percent, and low-temperature impact energy at minus 20 ℃ more than or equal to 270J.
1. In order to achieve the above purpose, the present invention adopts the following technical scheme:
the manufacturing method of the weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following chemical components in percentage by weight: 0.05 to 0.09 weight percent, si:0.15 to 0.35 weight percent, mn:1.10 to 1.30 weight percent, P is less than or equal to 0.020 weight percent, S is less than or equal to 0.008 weight percent, nb:0.030 to 0.045wt percent, ti:0.010 to 0.020wt%, cr:0.40 to 0.55 weight percent, ni:0.30 to 0.40 weight percent, cu:0.25 to 0.35 weight percent, alt:0.020 to 0.040 weight percent, and N is less than or equal to 0.005 weight percent; the balance of Fe and unavoidable trace elements.
The manufacturing method of the weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following process routes: blast furnace molten iron smelting, molten iron desulfurization pretreatment, converter molten steel smelting, LF molten steel refining, RH molten steel refining, slab continuous casting, hot plate blank heating, descaling, rough rolling, finish rolling, straightening, sampling, steel plate II-level flaw detection and marking and warehousing.
The specific technical measures comprise:
(1) The low-carbon component design is adopted, the C range in the steel is controlled to be 0.05-0.09 wt%, the impact toughness of the steel plate can be effectively improved, and the steel plate has low welding crack sensitivity; the N in the steel is controlled to be less than or equal to 0.005wt%, the precipitation of Ti and N in liquid molten steel in the slab continuous casting process is reduced, and the damage of the coarse TiN precipitates to the toughness of the steel plate for the welded structure can be reduced.
(2) Nb in the design steel: 0.030 to 0.045 weight percent, fully exerting the grain refinement, improving the impact toughness of the steel and reducing the brittle transition temperature; ti in the design steel: 0.010 to 0.020wt percent, the N content of the steel reacting with Al element is reduced, the AlN precipitation is restrained, and the surface cracks of the casting blank are effectively reduced.
(3) Smelting converter molten steel: the requirement of S for molten iron to enter the furnace is less than or equal to 0.010 weight percent; the whole process of smelting adopts bottom blowing argon; converter end point control C:0.04 to 0.06 weight percent, and P is less than or equal to 0.015 weight percent;
(4) Refining LF molten steel: removing impurities, balancing temperature and alloying treatment of molten steel in an LF furnace;
(5) Refining RH molten steel: the total circulation time of the vacuum is 15-20 min, and the holding time of the extreme vacuum is more than 10min; the net circulation time is more than 3 min; soft argon blowing time is 8-10 min after calcium treatment; molten steel sedation time: 15-30 min;
(6) Continuous slab casting: the ladle slag discharge detection control is adopted, the pouring temperature of the tundish is 1530-1560 ℃, the alkaline covering agent is used for the tundish, the low alloy steel covering slag is used for the tundish, and the casting blank pulling speed is 0.85-1.16 m/min.
(7) Rolling the medium plate: controlling the soaking temperature of a casting blank heating furnace to be 1160-1240 ℃, ensuring that the heating time of the casting blank in the furnace is more than or equal to 210min and the soaking time is more than or equal to 35min, enabling microalloying elements Nb and Ti to be in solid solution and controlling the austenite grain size; the rough rolling last pass adopts manual large-reduction rolling to uniformly hot-rolled state tissues, so that the plate shape of the steel plate and the stamping performance after rolling are improved; finish rolling 8-pass continuous rolling, wherein the cogging thickness, the finish rolling start rolling target temperature and the finish rolling target temperature of finished products with different thicknesses are shown in table 1. The cooling water of the rolling mill and the cooling water after rolling are not used after the steel plate is rolled.
TABLE 1 cogging and controlled rolling schemes for different thicknesses
2. Examples
(1) The invention provides a weather-proof bridge steel plate Q345qDNH with high impact toughness and a manufacturing method thereof, wherein the weather-proof bridge steel plate Q345qDNH with high impact toughness adopts the following component proportion and specific process. Wherein, table 2 is the composition (in weight percent) of each example steel as follows:
the weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following chemical components: c:0.071wt%, si:0.25wt%, mn:1.22wt%, P:0.014wt%, S:0.003wt%, nb:0.040wt%, ti:0.019wt%, cr:0.45wt%, ni:0.33wt%, cu:0.28wt%, alt:0.026wt%, N:0.0045wt%; the balance of Fe and unavoidable trace elements;
the weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following chemical components: c:0.064wt%, si:0.25wt%, mn:1.18wt%, P:0.013wt%, S:0.004wt%, nb:0.037wt%, ti:0.017wt%, cr:0.45wt%, ni:0.32wt%, cu:0.27wt%, alt:0.029wt%, N:0.0038wt%; the balance of Fe and unavoidable trace elements;
the weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following chemical components: c:0.080wt%, si:0.23wt%, mn:1.20wt%, P:0.013wt%, S:0.001wt%, nb:0.034wt%, ti:0.015wt%, cr:0.46wt%, ni:0.32wt%, cu:0.27wt%, alt:0.031wt%, N:0.0037wt%; the balance of Fe and unavoidable trace elements;
the weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following chemical components: c:0.067wt%, si:0.24wt%, mn:1.18wt%, P:0.012wt%, S:0.003wt%, nb:0.034wt%, ti:0.018wt%, cr:0.44wt%, ni:0.33wt%, cu:0.27wt%, alt:0.033wt%, N:0.0042wt%; the balance of Fe and unavoidable trace elements;
table 2: chemical composition (wt%)
Examples C Si Mn P S Alt Nb Ti Cr Ni Cu N
Example 1 0.071 0.25 1.22 0.014 0.003 0.026 0.040 0.019 0.45 0.33 0.28 0.0045
Example 2 0.064 0.25 1.18 0.013 0.004 0.029 0.037 0.017 0.45 0.32 0.27 0.0038
Example 3 0.080 0.23 1.20 0.013 0.001 0.031 0.034 0.015 0.46 0.32 0.27 0.0037
Example 4 0.067 0.24 1.18 0.012 0.003 0.033 0.034 0.018 0.44 0.33 0.27 0.0042
(2) Specific process parameters of the weather-resistant bridge steel plate Q345qDNH with high impact toughness, which is rolled to have the thickness of 8-30mm, are shown in table 3, wherein the thickness of the weather-resistant bridge steel plate Q345qDNH with high impact toughness is 10mm, 16mm, 20mm and 25mm respectively, and table 3 is the process parameters corresponding to the example steels shown in table 2.
Table 3: specific process parameters of the examples
(3) The weather-resistant bridge steel plate Q345qDNH with high impact toughness has detailed mechanical properties shown in Table 4, the mechanical properties ReL of the weather-resistant bridge steel plate Q345qDNH obtained by the invention are more than or equal to 400MPa, the tensile strength Rm is more than or equal to 500MPa, the elongation A is more than or equal to 26 percent, the low-temperature impact energy at-20 ℃ is more than or equal to 270J, and Table 4 shows the mechanical properties corresponding to the component steels in each embodiment shown in Table 2.
Table 4: mechanical Properties of the examples
Examples Thickness/mm of finished product R eL /MPa R m /MPa A/％ Low temperature impact energy A at-20 DEG C kv /J
Example 1 10 452 596 27.3 273
Example 2 16 451 548 29.8 327
Example 3 20 431 536 29.5 351
Example 4 25 424 518 28.2 307
(4) The thickness range of the weather-resistant bridge steel plate Q345qDNH finished product with high impact toughness is 10-25 mm, the metallographic structures are F+P, the F grain size level is 10.5-10.0, the metallographic structure data of each example are shown in Table 5, the metallographic structure photo of example 1 is shown in FIG. 1, and the metallographic structure photo of example 4 is shown in FIG. 2.
Table 5: metallographic structure data of each example
Examples Thickness/mm of finished product Tissue of F grain size/grade
Example 1 10 F+P 10.5
Example 2 16 F+P 10.5
Example 3 20 F+P 10.0
Example 4 25 F+P 10.0
The invention provides a novel tool by reasonable design of components and production processAccording to the requirements of national standard GB/T714 components, cu, ni and Cr elements are added into steel to ensure weather resistance, a proper amount of Nb+Ti microalloy is added into the steel through the design of low carbon components in the steel, the N content in the steel is strictly controlled, a reasonable smelting-continuous casting-rolling process is formulated, stable production of the product is realized, and the weather-resistant bridge steel plate Q345qDNH with stable mechanical property and high impact toughness is obtained. The weather-resistant bridge steel plate Q345qDNH mechanical property R obtained by the invention eL More than or equal to 400MPa, tensile strength Rm more than or equal to 500MPa, elongation A more than or equal to 26 percent, and low-temperature impact energy at minus 20 ℃ more than or equal to 270J.
The foregoing is illustrative of the present invention and is not to be construed as limiting the scope of the invention. In order that the components of the invention may be combined without conflict, any person skilled in the art shall make equivalent changes and modifications without departing from the spirit and principles of the invention.

Claims (10)

1. The manufacturing method of the weather-resistant bridge steel plate Q345qDNH with high impact toughness is characterized by comprising the following chemical components in percentage by weight: c:0.05 to 0.09 weight percent, si:0.15 to 0.35 weight percent, mn:1.10 to 1.30 weight percent, P is less than or equal to 0.020 weight percent, S is less than or equal to 0.008 weight percent, nb:0.030 to 0.045wt percent, ti:0.010 to 0.020wt%, cr:0.40 to 0.55 weight percent, ni:0.30 to 0.40 weight percent, cu:0.25 to 0.35 weight percent, alt:0.020 to 0.040 weight percent, and N is less than or equal to 0.005 weight percent; the balance of Fe and unavoidable trace elements; the yield strength R of the weather-resistant bridge steel plate Q345qDNH product with high impact toughness eL Not less than 400MPa, tensile strength R m More than or equal to 500MPa, the elongation A more than or equal to 26 percent, and the low-temperature impact energy at minus 20 ℃ more than or equal to 270J.
The manufacturing method of the weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following sequentially performed process steps:
blast furnace molten iron smelting, molten iron desulfurization pretreatment, converter molten steel smelting, LF molten steel refining, RH molten steel refining, slab continuous casting, hot plate blank heating, descaling, rough rolling, finish rolling, straightening, sampling, steel plate II-level flaw detection and marking warehousing;
wherein the soaking temperature of the casting blank heating furnace is controlled to be 1160-1240 ℃.
2. The method for manufacturing the weather-resistant bridge steel plate Q345qDNH with high impact toughness according to claim 1, wherein the heating time of a casting blank in a furnace is more than or equal to 210min, and the soaking time is more than or equal to 35min.
3. The method for producing a weather-resistant bridge steel sheet Q345qDNH with high impact toughness according to claim 1, wherein the finish rolling is set to 8-pass continuous rolling.
4. The method for producing a weather-resistant bridge steel sheet Q345qDNH with high impact toughness according to claim 1, wherein the weather-resistant bridge steel sheet Q345qDNH with high impact toughness is not rolled with rolling mill cooling water or post-rolling cooling water.
5. The method for producing a weather-resistant bridge steel sheet Q345qDNH having high impact toughness according to claim 1, wherein when the thickness of the finished product of the weather-resistant bridge steel sheet Q345qDNH having high impact toughness is δ, δ is 8.ltoreq.10 mm, the finish rolling start temperature is 1030.+ -. 30 ℃ and the finish rolling temperature is 850.+ -. 30 ℃.
6. The method for producing a weather-resistant bridge steel sheet Q345qDNH having high impact toughness according to claim 1, wherein when the thickness of the finished product of the weather-resistant bridge steel sheet Q345qDNH having high impact toughness is delta, delta is 10mm < delta < 16mm, the finish rolling start temperature is 960.+ -. 30 ℃ and the finish rolling temperature is 850.+ -. 30 ℃.
7. The method for producing a weather-resistant bridge steel sheet Q345qDNH having high impact toughness according to claim 1, wherein the finish rolling start temperature is 920.+ -. 30 ℃ and the finish rolling temperature is 840.+ -. 30 ℃ when the finished product thickness of the weather-resistant bridge steel sheet Q345qDNH having high impact toughness is δ,16mm < δ.ltoreq.20 mm.
8. The method for producing a weather-resistant bridge steel sheet Q345qDNH having high impact toughness according to claim 1, wherein when the thickness of the finished product of the weather-resistant bridge steel sheet Q345qDNH having high impact toughness is δ,20mm < δ.ltoreq.30 mm, the finish rolling start temperature is 890.+ -. 30 ℃ and the finish rolling temperature is 820.+ -. 30 ℃.
9. The method for producing a weather-resistant bridge steel sheet Q345qDNH with high impact toughness according to claim 1, wherein the converter molten steel is smelted: the molten iron requirement S is less than or equal to 0.010 weight percent, the whole process of bottom blowing argon is adopted in the smelting process, and the converter end point control C:0.04 to 0.06 weight percent, and P is less than or equal to 0.015 weight percent.
10. Weather-resistant bridge steel plate Q345qDNH with high impact toughness, which is characterized by being prepared by the method according to any one of claims 1 to 9, wherein the weather-resistant bridge steel plate Q345qDNH with high impact toughness comprises the following chemical components in percentage by weight: c:0.05 to 0.09 weight percent, si:0.15 to 0.35 weight percent, mn:1.10 to 1.30 weight percent, P is less than or equal to 0.020 weight percent, S is less than or equal to 0.008 weight percent, nb:0.030 to 0.045wt percent, ti:0.010 to 0.020wt%, cr:0.40 to 0.55 weight percent, ni:0.30 to 0.40 weight percent, cu:0.25 to 0.35 weight percent, alt:0.020 to 0.040 weight percent, and N is less than or equal to 0.005 weight percent; the balance of Fe and unavoidable trace elements.
CN202310549618.2A 2023-05-16 2023-05-16 Weather-resistant bridge steel plate Q345qDNH with high impact toughness and manufacturing method Pending CN116555667A (en)

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