CN116497280A - 700 MPa-grade hot-rolled high-strength high-weather-resistance steel and preparation method and application thereof - Google Patents

700 MPa-grade hot-rolled high-strength high-weather-resistance steel and preparation method and application thereof Download PDF

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Publication number
CN116497280A
CN116497280A CN202310477994.5A CN202310477994A CN116497280A CN 116497280 A CN116497280 A CN 116497280A CN 202310477994 A CN202310477994 A CN 202310477994A CN 116497280 A CN116497280 A CN 116497280A
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steel
weather
groups
hot
heating
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Inventor
刘锟
张旭
姜杉
原园
牛涛
庞陆峰
白凤霞
黄天华
梁江涛
韩赟
田志红
徐永先
李飞
徐海卫
王伦
惠亚军
王学强
于孟
缪成亮
朱国森
安瑞东
李�瑞
李悦
郭慧敏
李永林
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Shougang Group Co Ltd
Beijing Shougang Co Ltd
Shougang Jingtang United Iron and Steel Co Ltd
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Shougang Group Co Ltd
Beijing Shougang Co Ltd
Shougang Jingtang United Iron and Steel Co Ltd
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Priority to CN202310477994.5A priority Critical patent/CN116497280A/en
Publication of CN116497280A publication Critical patent/CN116497280A/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
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
    • B21B3/02—Rolling special iron alloys, e.g. stainless steel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • 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
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C21D2211/004—Dispersions; Precipitations
    • 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
    • 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
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Abstract

The application relates to the field of weather-resistant steel materials, in particular to 700 MPa-grade hot-rolled high-strength high-weather-resistant steel, and a preparation method and application thereof; the hot rolled high-strength high-weather-resistance steel comprises the following chemical components in percentage by mass: c:0.043% -0.048%, si:0.51 to 0.59 percent, mn:0.61% -0.68%, P:0.041 to 0.049 percent, S:0.0031% -0.0038%, al:0.071% -0.079%, ti:0.092% -0.099%, cu:0.251% -0.259%, cr:1.81 to 1.98 percent, N:0.0031% -0.0034%, and the balance of Fe and unavoidable impurities; the microalloying design with low C content, low Mn content and high Ti content is adopted, the strength of the whole high weather resistant steel is improved, the deformation resistance in the rolling process is reduced, the rolling stability is good, the composite weather resistance design is carried out aiming at Si, P, cu and Cr elements, the contribution of low-cost weather resistant elements such as Si, P and the like to weather resistance and solid solution strengthening is fully exerted, the adverse influence of chromium carbide on weather resistance and toughness is reduced by utilizing Cu, the synchronous improvement of weather resistance and toughness is realized, and meanwhile, the rolling difficulty and the alloy cost can be reduced.

Description

700 MPa-grade hot-rolled high-strength high-weather-resistance steel and preparation method and application thereof
Technical Field
The application relates to the field of weather-resistant steel materials, in particular to 700 MPa-grade hot-rolled high-strength high-weather-resistant steel, and a preparation method and application thereof.
Background
The weathering steel is used as a functional structural steel with good atmospheric corrosion resistance, is widely applied to the fields of containers, railway vehicles, bridges, buildings, towers, photovoltaic brackets and the like, but the problems of insufficient light weight and corrosion resistance and low service life exist commonly at present, and the problems of excessive addition of noble alloy, high cost, welding performance deviation and the like exist in the potential solution, so that the green high-quality development of the steel structure industry is restricted. At present, the weathering steel with the highest strength grade is 700MPa grade in yield strength, and the thin-specification high-strength weathering steel with the thickness of 700MPa and above can be classified into a Cr-Ni-Cu system, a Cr-Ni-Cu-P system and a Cr-Cu-P system according to weathering alloy elements, and the Cr-Ni-Cu system is the main system at present. But has the following disadvantages:
1) Cr-Ni-Cu weather-resistant alloy system: the main system is added with a large amount of noble alloy Ni element, so that the cost is high, the economy is low, the alloy content of part of the system is high, the smelting and rolling difficulties are high, and the problem of welding formability deviation exists;
2) Cr-Ni-Cu-P weather-resistant alloy system: the system is mainly applied to a thin slab continuous casting and rolling line and a thin strip casting and rolling line, but has the problems of high microalloying cost, high rolling deformation resistance of thin-specification strip steel containing noble alloy Ni element, and insufficient contribution of economic phosphorus element to weather resistance;
3) Cr-Cu-P weather-resistant alloy system: the system has poor weather resistance and is difficult to meet the requirement of high weather resistance.
Therefore, how to provide a hot rolled high strength and high weather resistant steel containing no or a small amount of precious metal elements to reduce the rolling difficulty and the alloy cost is a technical problem which needs to be solved at present.
Disclosure of Invention
The application provides 700 MPa-grade hot-rolled high-strength high-weather-resistant steel and a preparation method and application thereof, and aims to solve the technical problems that in the prior art, the rolling difficulty is too large and the alloy cost is too high due to excessive addition of precious alloy in the high-weather-resistant steel.
In a first aspect, the present application provides a 700 MPa-grade hot rolled high strength high weathering steel comprising, in mass fractions: c:0.043% -0.048%, si:0.51 to 0.59 percent, mn:0.61% -0.68%, P:0.041 to 0.049 percent, S:0.0031% -0.0038%, al:0.071% -0.079%, ti:0.092% -0.099%, cu:0.251% -0.259%, cr:1.81 to 1.98 percent, N:0.0031% -0.0034% and the balance of Fe and unavoidable impurities.
Optionally, the structure of the hot rolled high strength and high weather resistance steel comprises ferrite and TiC nano-scale precipitates, wherein the nano-scale precipitated phase with the grain size of 2 nm-5 nm in the ferrite accounts for more than 88% of the TiC nano-scale precipitates.
Optionally, the thickness h of the hot rolled high strength and high weather resistance steel is 1.2 mm-8.0 mm.
In a second aspect, the present application provides a method of preparing the hot rolled high strength high weathering steel of the first aspect, the method comprising:
obtaining a casting blank containing the same chemical components as the hot-rolled high-strength high-weather-resistance steel in the first aspect;
heating the casting blank, and then sequentially performing rough descaling and rough rolling to obtain an intermediate plate blank;
and (3) performing fine descaling, finish rolling, ultra-fast cooling and laminar cooling on the intermediate slab, and coiling to obtain the hot-rolled high-strength high-weather-resistance steel.
Optionally, the heating comprises a preheating section, a heating section I, a heating section II and a soaking section II, wherein the heating rate of the preheating section is 16 ℃/min-19 ℃/min, and the section end temperature of the preheating section is more than or equal to 850 ℃;
the end temperature T1 of the heating section is as follows:
T1＝T*(0.936-0.013h+0.0020h 2 )；
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; t is the tapping temperature of the heating; and/or the number of the groups of groups,
the section end temperature T2 of the heating two sections meets the following conditions:
T2＝T*(1.016-0.015h+0.0018h 2 )；
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; t is the tapping temperature of the heating; and/or the number of the groups of groups,
the segment end temperature T of the soaking segment meets the following conditions:
T＝1262-8.33h；
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; t is the tapping temperature of the heating.
Optionally, the atmosphere of the preheating section is a strong oxidizing atmosphere, and the air excess coefficient alpha of the preheating section is 1.40-1.50; and/or the number of the groups of groups,
the atmosphere of the heating section is a weak oxidizing atmosphere, and the air excess coefficient alpha 1 of the heating section meets the following conditions:
α1＝1.15-0.025h，
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; and/or the number of the groups of groups,
the atmosphere of the heating second section is a weak oxidizing atmosphere, and the air excess coefficient alpha 2 of the heating second section meets the following conditions:
α2＝1.13-0.027h，
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm;
the atmosphere of the soaking section is a weak oxidizing atmosphere, and the air excess coefficient alpha 3 of the soaking section meets the following conditions:
α3＝1.11-0.029×h，
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm.
Optionally, the heating further comprises heating in a mode of controlling the total heating time to be more than or equal to 110min under the temperature condition of above 1100 ℃, wherein the total heating time t meets the following conditions:
t＝135-3.10h，
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; and/or the number of the groups of groups,
the time of the soaking section is 51-59 min.
Optionally, the rough rolling comprises a first rough rolling and a second rough rolling,
the total rolling reduction of the first rough rolling is 32.2-34.9%, the total rolling reduction of the second rough rolling is 49.3-51.9%, and the outlet temperature of the second rough rolling is 1061-1079 ℃; and/or the number of the groups of groups,
the finish rolling comprises the step of adopting a continuous finish rolling mode to finish rolling, wherein the outlet temperature of the finish rolling is 826-848 ℃.
Optionally, the ultra-fast cooling comprises cooling by adopting ultra-fast water cooling water, wherein the pressure of the ultra-fast cooling is 0.37-0.39 MPa, the outlet temperature of the ultra-fast cooling is 625-639 ℃, and the speed of the ultra-fast cooling is 51-79 ℃/s; and/or the number of the groups of groups,
the laminar cooling is carried out by adopting a mode of shielding hot rolled strip steel at the edge, and the width of the edge shielding is 210-240 mm; and/or the number of the groups of groups,
the coiling comprises coiling in a step-type U-shaped temperature mode of controlling the temperature of the finished strip steel body and the temperature of the head and the tail of the strip steel, wherein the coiling temperature of the strip steel body is 555-575 ℃; and/or the number of the groups of groups,
the coiling temperature at the position 0-15 m away from the head and the tail of the strip steel is 585-605 ℃; and/or the number of the groups of groups,
the coiling temperature at the position 16 m-30 m away from the head and the tail of the strip steel is 575-595 ℃; and/or the number of the groups of groups,
the coiling temperature at the position 31 m-45 m away from the head and the tail of the strip steel is 565-585 ℃.
In a third aspect, the present application provides a use of the hot rolled high strength high weathering steel of the first aspect, the use comprising: the hot rolled high strength and high weather resistant steel of the first aspect is used in a coating-free steel structure in a C1 to C3 atmospheric environment.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
compared with the traditional weathering steel system, the 700 MPa-level hot-rolled high-strength high-weathering steel provided by the embodiment of the application adopts a microalloying design with low C content, low Mn content and high Ti content, the strength of the whole high-weathering steel is improved by utilizing the separated microalloying precipitate, meanwhile, the deformation resistance in the rolling process can be reduced, the rolling stability is good, meanwhile, the composite weathering resistance design is carried out for Si, P, cu and Cr elements, the contribution of the low-cost weathering resistance elements such as Si, P and the like to weathering resistance and solid solution strengthening is fully exerted, the addition of Cu is utilized, the addition amount of Cr elements can be effectively reduced, the precipitate of chromium carbide is formed between the Cr elements and C, the adverse influence of the chromium carbide on weathering resistance and toughness is further reduced, the synchronous improvement of weathering resistance and toughness is realized, and meanwhile, the addition of valuable alloy elements such as Ni, nb, V and Mo is avoided, and the rolling difficulty and the alloy cost are reduced.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the description of the embodiments or the prior art will be briefly described below, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without inventive effort.
FIG. 1 is a schematic diagram of a metallographic structure of a hot rolled high strength and high weather resistance steel according to an embodiment of the present application;
fig. 2 is a schematic flow chart of the preparation of hot rolled high strength and high weather resistance steel according to the embodiment of the present application.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.
Unless specifically indicated otherwise, the various raw materials, reagents, instruments, equipment, and the like used in this application are commercially available or may be prepared by existing methods.
The inventive thinking of this application is:
the existing 700MPa thin high-strength weathering steel can be divided into Cr-Ni-Cu system, cr-Ni-Cu-P system and Cr-Cu-P system according to weathering resistance alloy elements, and the existing systems have the following problems:
1) Cr-Ni-Cu weather-resistant alloy system: the main system comprises: the content range of Cr is 0.30% -1.25%, the content range of Ni is 0.03% -0.80%, the content range of Cu is 0.10% -0.60%, such as patent application numbers CN200610123458, CN200710031548, CN201010246778, CN107365940B, CN109402508B and the like, although the weather resistance is increased by about 1 time compared with carbon steel, the requirements of less than or equal to 55% of relative corrosion rate in a field and an industrial atmospheric environment can be met, but the requirements of high weather resistance of less than or equal to 37% of relative corrosion rate are not met, noble alloy Ni elements are added more, the cost is higher, and the economical efficiency is not strong; part adopts a high Cr-high Ni-Cu weather-resistant alloy system, such as 2.50 to 10.00 percent of Cr, 0.20 to 1.00 percent of Ni and 0.20 to 0.50 percent of Cu in the weather-resistant steel with the yield strength of more than 700MPa and the manufacturing method thereof in the patent application No. CN200910056602, and has better weather resistance, but has the problems of high alloy content, high smelting and rolling difficulty and welding formability deviation.
2) Cr-Ni-Cu-P weather-resistant alloy system: the component system is mainly applied to a sheet billet continuous casting and rolling production line and a sheet strip casting and rolling production line, for example, 0.05-0.20% of vanadium is adopted in a method for producing 700 MPa-grade V-N microalloyed high-strength atmospheric corrosion resistant steel based on a sheet billet continuous casting and rolling process in patent application number CN200610035800.2, and vanadium-nitrogen microalloying is utilized; the method comprises the steps that 0.03-0.05% of Ti and 0.25-0.45% of Mo are adopted for compound microalloying in a 700 MPa-grade high-strength weather-resistant steel belt and a CSP process production method thereof in patent application number CN 201911108607.0; for example, in the patent application No. CN201810587493.1, 0.05 to 0.20 percent of Nb and 0.05 to 0.20 percent of V are adopted for composite microalloying in the process of casting and rolling 700MPa grade weathering steel with thin strip and the production method thereof; for example, in the patent application No. CN201210066986.3, nb, V, ti and Mo elements are adopted for composite microalloying in a manufacturing method of thin strip continuous casting 700 MPa-level high-strength weathering steel; however, the series of patents all have the problems of high microalloying cost, high rolling deformation resistance of thin-specification strip steel, and insufficient contribution of economic phosphorus element to weather resistance.
3) Cr-Cu-P weather-resistant alloy system: the weathering steel for the wide 700 MPa-level hot rolled container and the manufacturing method thereof adopt the design of low weathering alloy of 0.22 to 0.29 percent of Cr, 0.11 to 0.19 percent of Cu and 0.035 to 0.045 percent of P in the patent application No. CN202010362920.3, the weathering index is low, and the high weathering requirement can not be met.
Therefore, how to provide a hot rolled high strength and high weather resistant steel containing no or a small amount of precious metal elements to reduce the rolling difficulty and the alloy cost is a technical problem which needs to be solved at present.
The embodiment of the application provides 700 MPa-grade hot-rolled high-strength high-weather-resistance steel, which comprises the following chemical components in percentage by mass: c:0.043% -0.048%, si:0.51 to 0.59 percent, mn:0.61% -0.68%, P:0.041 to 0.049 percent, S:0.0031% -0.0038%, al:0.071% -0.079%, ti:0.092% -0.099%, cu:0.251% -0.259%, cr:1.81 to 1.98 percent, N:0.0031% -0.0034% and the balance of Fe and unavoidable impurities.
In the embodiment of the application, the positive effect of limiting the mass fraction of C to be 0.043% -0.048% is that the strength of the steel is improved by solid solution strengthening and precipitation strengthening of interaction with microalloy elements, but when the content of C is higher, the formability and weldability of the steel are poor, meanwhile, the structural uniformity is poor, micro-area galvanic corrosion is formed, and the weather resistance of the steel is reduced; when the content of C is low, the effects of solid solution strengthening and precipitation strengthening are insufficient, and the strength of the steel is low, so that the content of C is controlled to be 0.043-0.048%.
The mass fraction of Si is 0.51% -0.59%, and the Si mainly plays a solid solution strengthening role, so that the content of Si is improved, alpha FeOOH in the rust layer in the weathering steel can be thinned, the resistance of the rust layer is increased, and the weathering resistance of the steel is improved; the Si content is increased, the P content is increased, and through the synergistic effect of the Si content and the P content, the red rust defect on the surface of steel can be effectively inhibited, and on the other hand, the Cu element enrichment at a low temperature section in the heating process of a plate blank can be inhibited, the Cu element diffusion at a high temperature section is promoted, and the Cu enrichment quantity at a unit interface of an iron sheet and a steel matrix is reduced, so that the copper embrittlement is inhibited; however, the Si content is too high, which is detrimental to the toughness and weldability of the strip steel, so that the Si content is controlled to be 0.51% -0.59%.
The positive effect of Mn with mass fraction of 0.61-0.68% is that Mn mainly plays the roles of solid solution strengthening and fine grain strengthening, but Mn is an easily segregated element, the content of Mn is too high, which leads to the increase of banded structure, the anisotropy of steel is obvious, the formability and the weldability are deteriorated, and the weather resistance is also reduced, so that the content of Mn is controlled to be 0.61-0.68%.
The positive effect that the mass fraction of P is 0.041-0.049% is that the P is an important solid solution strengthening element, is the most economic and effective element for improving the weather resistance of the steel, can cooperate with Si element to reduce the red rust defect on the surface of the steel with high Si content, and can cooperate to inhibit the copper embrittlement defect of the steel with Cu, but the content is too high, so that the cold brittleness, weldability and plasticity are poor, and the content of P needs to be controlled to be 0.041-0.049%.
The mass fraction of S is 0.0031% -0.0038%, and the positive effects are that sulfide inclusion formed by S can reduce the plasticity and toughness of steel, and meanwhile, the S is used as a pitting source to cause the deterioration of weather resistance; for Ti microalloyed steel, large particle carbosulfide Ti is formed 4 C 2 S 2 The content of effective Ti can be reduced; however, the content of S is controlled to be too low, the refining desulfurization burden is obviously increased, and the desulfurization cost is increased, so that the content of S is controlled to be 0.0031-0.0038%.
The positive effect of the Al with the mass fraction of 0.071-0.079% is that the Al is an important deoxidizing element and fine-grain strengthening element, and is also an element for improving the compactness of the weathering steel rust layer, but the Al belongs to an extremely active element, and special covering slag needs to be adapted when the content is higher, so that the continuous casting cost is increased.
The mass fraction of Ti is 0.092% -0.099%, and the positive effects are that Ti is a strong carbonitride forming element, is the most economic and effective fine crystal and precipitation strengthening element, and meanwhile, ti and P element are added in a compounding way, so that a certain amount of iron-titanium-phosphorus phases are formed, grain boundary segregation of the P element is reduced, and the play of the effect of improving weather resistance of the P element is promoted; however, when the Ti content is too high, coarse TiN or TiC particles are formed, and the toughness of the steel is deteriorated, so that the Ti content is controlled to be 0.092% -0.099%.
The mass fraction of Cu is 0.251% -0.259%, and the positive effects are that Cu has the effects of activating a cathode and promoting anode passivation in steel, is an important element for improving the weather resistance of steel, and can obviously improve the weather resistance by adding a proper amount, the weather resistance is increased to a small extent when more Cu is added, and the risk of Cu brittle defects is obviously increased, so that the content of Cu is controlled to be 0.251% -0.259%.
The mass fraction of Cr is 1.81-1.98%, and the positive effects are that Cr is an important solid solution strengthening element, when a small amount of Cr is added, the weathering resistance can be enriched and improved in the rust layer in the steel, and when a large amount of Cr is added, a passivation film can be formed on the surface of the steel, so that the weathering resistance can be further improved, but when the Cr content is higher, a large amount of CrxCy can be formed in the steel, and the plasticity, the toughness, the formability and the welding performance of the steel are deteriorated, so that the Cr content is controlled to be 1.81-1.98%.
The positive effect of the mass fraction of N being 0.0031% -0.0034% is that N is easy to combine with Ti element to form large-particle TiN, a part of Ti is consumed, so that the content of effective Ti is reduced, meanwhile, the plasticity of steel is deteriorated, but the degassing cost of a refining process is obviously increased by controlling the content of N to be too low, and the content of N is controlled to be in a narrow range from the viewpoint of improving the performance stability of a product, so that the content of N is controlled to be 0.0031% -0.0034%.
In some alternative embodiments, as shown in fig. 1, the structure of the hot rolled high strength high weathering steel includes ferrite and TiC nano-sized precipitates, wherein the nano-sized precipitates having a grain size of 2nm to 5nm in the ferrite account for 88% or more of the TiC nano-sized precipitates.
In the embodiment of the application, the precipitates with the grain size of 2-5 nm in ferrite are limited to be main precipitation forms, which shows that the high-strength high-weather-resistant steel obtained by the application has excellent performance, so that the product with the yield strength of more than or equal to 700MPa, the tensile strength of more than or equal to 800MPa, the elongation after break of more than or equal to 18%, the impact energy of more than or equal to 47J at minus 40 ℃ and the rolling yield strength fluctuation of less than or equal to 65MPa is obtained.
In some alternative embodiments, the thickness h of the hot rolled high strength high weathering steel is from 1.2mm to 8.0mm.
In the embodiment of the application, the specific thickness of the hot-rolled high-strength high-weather-resistant steel is limited, and the excellent performance of the high-strength high-weather-resistant steel is ensured, so that the product with the yield strength of more than or equal to 700MPa, the tensile strength of more than or equal to 800MPa, the elongation after fracture of more than or equal to 18 percent, the impact energy of more than or equal to 47J at minus 40 ℃ and the rolling yield strength fluctuation of less than or equal to 65MPa is obtained.
As shown in fig. 2, the present application provides a method of preparing the hot rolled high strength and high weather resistance steel, the method comprising:
s1, obtaining a casting blank containing the same chemical components of the hot-rolled high-strength high-weather-resistance steel;
s2, heating the casting blank, and then sequentially performing rough descaling and rough rolling to obtain an intermediate plate blank;
s3, performing fine descaling, finish rolling, ultra-fast cooling and laminar cooling on the intermediate slab, and coiling to obtain the hot-rolled high-strength high-weather-resistance steel.
In the embodiment of the application, the high-strength high-weather-resistance steel raw material with target chemical components is processed according to the rough process of smelting, continuous casting blank heating, rough descaling, fixed-width press, rough rolling, flying shear, fine descaling, finish rolling, ultra-fast cooling and laminar cooling, and coiling into a steel coil, so that a steel product meeting the expected strength and weather resistance can be obtained.
The method is directed to the preparation method of the hot-rolled high-strength high-weather-resistant steel, and the specific composition of the hot-rolled high-strength high-weather-resistant steel can refer to the above embodiment.
In some optional embodiments, the heating comprises a preheating section, a first heating section, a second heating section and a soaking section, wherein the heating rate of the preheating section is 16-19 ℃ per minute, and the end temperature of the preheating section is more than or equal to 850 ℃;
the end temperature T1 of the heating section is as follows:
T1＝T*(0.936-0.013h+0.0020h 2 )；
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; t is the furnace outlet temperature of heating, and the temperature is DEG C; and/or the number of the groups of groups,
the section end temperature T2 of the heating two sections meets the following conditions:
T2＝T*(1.016-0.015h+0.0018h 2 )；
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; t is the furnace outlet temperature of heating, and the temperature is DEG C; and/or the number of the groups of groups,
the segment end temperature T of the soaking segment meets the following conditions:
T＝1262-8.33h；
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; t is the tapping temperature of the heating, and the temperature is DEG C.
In the embodiment of the application, the temperatures of the preheating section, the heating first section, the heating second section and the soaking section in the heating process are changed along with the thickness of the final strip steel product, so that the oxidation enrichment of copper elements at the interface between an iron sheet and a steel matrix in the low-temperature stage is reduced, the enrichment quantity of copper elements at the interface is reduced, the copper embrittlement hazard of a liquid copper-rich phase in the subsequent rolling process is reduced, and the quality problem of copper embrittlement of the surface of the strip steel caused by the design of a chemical component system without nickel and with low cost is avoided.
In some alternative embodiments, the atmosphere of the preheating section is a strong oxidizing atmosphere, and the air excess coefficient alpha of the preheating section is 1.40-1.50; and/or the number of the groups of groups,
the atmosphere of the heating section is a weak oxidizing atmosphere, and the air excess coefficient alpha 1 of the heating section meets the following conditions:
α1＝1.15-0.025h，
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; and/or the number of the groups of groups,
the atmosphere of the heating second section is a weak oxidizing atmosphere, and the air excess coefficient alpha 2 of the heating second section meets the following conditions:
α2＝1.13-0.027h，
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm;
the atmosphere of the soaking section is a weak oxidizing atmosphere, and the air excess coefficient alpha 3 of the soaking section meets the following conditions:
α3＝1.11-0.029×h，
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm.
In the embodiment of the application, the specific atmosphere and the air excess coefficient of each stage in the heating process are limited, and the diffusion of copper elements enriched at the interface of the iron sheet and the steel matrix into the iron sheet and the steel matrix is accelerated through long-time heat preservation of the weak oxidizing atmosphere, so that the enrichment quantity of the copper elements at the interface is effectively reduced, and the copper embrittlement hazard of the liquid copper-rich phase in the subsequent rolling process is reduced.
In summary, through adopting the design of a fine heating process system adopting the 'strong oxidizing atmosphere high-temperature quick-heating of the heating front section and the long-time heat preservation of the weak oxidizing atmosphere of the middle and rear sections', the oxidation enrichment of copper elements at the interface of the iron sheet and the steel matrix at the low-temperature stage is reduced through low-temperature quick heating; the copper element enriched at the interface of the iron sheet and the steel matrix is accelerated to diffuse into the iron sheet and the steel matrix by long-time heat preservation in the weak oxidizing atmosphere, so that the enrichment quantity of the copper element at the interface is effectively reduced, and the copper embrittlement hazard of the liquid copper-rich phase in the subsequent rolling process is reduced.
In some alternative embodiments, the heating further comprises controlling the total time of heating at a temperature above 1100 DEG C
Heating in a mode of more than or equal to 110min, wherein the total heating time t meets the following conditions:
t＝135-3.10h，
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; and/or the number of the groups of groups,
the time of the soaking section is 51-59 min.
In the embodiment of the application, the specific time for heating to more than 1000 ℃ and the thickness relation of the strip steel are limited, and the soaking period time is limited, so that the heating process can meet the requirements of 'high-temperature quick heating of strong oxidizing atmosphere in the heating front section and long-time heat preservation of weak oxidizing atmosphere in the middle and rear sections of heating', and the quality problem of copper embrittlement on the surface of the strip steel caused by the nickel-free low-cost design of 700 MPa-grade hot-rolled high-strength high-weather-resistant steel is avoided.
In some alternative embodiments, the rough rolling includes a first rough rolling and a second rough rolling,
the total rolling reduction of the first rough rolling is 32.2-34.9%, the total rolling reduction of the second rough rolling is 49.3-51.9%, and the outlet temperature of the second rough rolling is 1061-1079 ℃; and/or the number of the groups of groups,
the finish rolling comprises the step of adopting a continuous finish rolling mode to finish rolling, wherein the outlet temperature of the finish rolling is 826-848 ℃.
In the embodiment of the application, the rough rolling is sequentially performed by adopting two rough rolling mills (R1 and R2), a 3+3 mode is adopted, the rough rolling R1 and the rough rolling R2 are all rolled for three times, the rough rolling R1 adopts first, second and third descaling, the rough rolling R2 adopts first and third descaling, and the liquid copper-rich at the interface of the iron sheet and the steel matrix is removed together with the iron sheet by adopting a mode of increasing descaling passes of the rough rolling.
The specific rolling total reduction rate of rough rolling and finish rolling is limited, and a reduction strategy for reducing the three-pass reduction rate before rough rolling and increasing the three-pass reduction rate after rough rolling is adopted, so that the harmful effect of austenite grain boundary liquid copper-rich phase on the surface of the steel substrate is reduced.
The outlet temperature of the second rough rolling is 1061-1079 ℃, and the positive effect is that the outlet temperature of the strip steel after the rough rolling R2 is controlled below 1085 ℃ of the melting point of the liquid copper-rich phase in the temperature range;
the continuous finish rolling adopts a mode of 6-7 frames for continuous rolling, and the outlet temperature of the finish rolling is 826-848 ℃, so that the purposes of finishing rolling stability, fine crystal control and cooling after rolling are achieved in a lower finish rolling outlet temperature range, and the grain size of deformed austenite before phase transformation is refined.
In some alternative embodiments, the ultra-fast cooling comprises cooling by adopting ultra-fast water cooling water, wherein the pressure of the ultra-fast cooling is 0.37-0.39 MPa, the outlet temperature of the ultra-fast cooling is 625-639 ℃, and the speed of the ultra-fast cooling is 51-79 ℃/s; and/or the number of the groups of groups,
the laminar cooling is carried out by adopting a mode of shielding hot rolled strip steel at the edge, and the width of the edge shielding is 210-240 mm; and/or the number of the groups of groups,
the coiling comprises coiling in a step-type U-shaped temperature mode of controlling the temperature of the finished strip steel body and the temperature of the head and the tail of the strip steel, wherein the coiling temperature of the strip steel body is 555-575 ℃; and/or the number of the groups of groups,
the coiling temperature at the position 0-15 m away from the head and the tail of the strip steel is 585-605 ℃; and/or the number of the groups of groups,
the coiling temperature at the position 16 m-30 m away from the head and the tail of the strip steel is 575-595 ℃; and/or the number of the groups of groups,
the coiling temperature at the position 31 m-45 m away from the head and the tail of the strip steel is 565-585 ℃.
In the embodiment of the application, a cooling mode of ultra-fast cooling and laminar cooling is adopted after rolling, the pressure of the ultra-fast cooling is controlled to be 0.37-0.39 MPa, the outlet temperature of the ultra-fast cooling is controlled to be 625-639 ℃, and the speed of the ultra-fast cooling is controlled to be 51-79 ℃/s, so that the precipitation strengthening contribution and the fine grain strengthening contribution of Ti microalloying are considered, and the 700 MPa-grade finished strip steel is ensured to have good obdurability matching.
The specific form of laminar cooling is limited, the narrow performance control of the through-coiled steel performance is ensured by utilizing edge shielding and stepped U-shaped coiling, and insufficient precipitation quantity caused by lower temperature of the edges and the heads and the tails of the strip steel are avoided.
Based on one general inventive concept, the present application provides an application of the hot rolled high strength and high weather resistance steel, the application comprising: the hot-rolled high-strength high-weather-resistance steel is used for a coating-free steel structure in a C1-C3 atmospheric environment.
Based on the excellent performance of the hot-rolled high-strength high-weather-resistant steel, the hot-rolled high-strength high-weather-resistant steel can be used for manufacturing railway vehicles, containers, photovoltaic supports, highway guardrails, building scaffolds and the like, and the manufactured products can be applied to the fields of the photovoltaic supports, the highway guardrails, the building scaffolds and the like without coating under the C1-C3 atmospheric environment.
The application is realized based on the hot-rolled high-strength high-weather-resistant steel, and the specific composition of the hot-rolled high-strength high-weather-resistant steel can refer to the embodiment, and because the application adopts part or all of the technical schemes of the embodiment, the application at least has all the beneficial effects brought by the technical schemes of the embodiment, and the detailed description is omitted.
The present application is further illustrated below in conjunction with specific examples. It should be understood that these examples are illustrative only of the present application and are not intended to limit the scope of the present application. The experimental procedures, which are not specified in the following examples, are generally determined according to national standards. If the corresponding national standard does not exist, the method is carried out according to the general international standard, the conventional condition or the condition recommended by the manufacturer.
In the actual production process, the specific preparation process of the hot-rolled high-strength high-weather-resistance steel comprises the following steps of:
the chemical composition ratios shown in table 1 were used according to: smelting, continuous casting billet heating, rough descaling, fixed-width press, rough rolling, flying shear, fine descaling, finish rolling, ultra-fast cooling and laminar cooling, and coiling into a steel coil, wherein the concrete flow is as follows:
(1) Smelting and continuous casting: molten steel is smelted according to the set components and poured into billets, and the chemical elements of the molten steel are shown in the following table 1 in percentage by mass.
TABLE 1 chemical composition of high strength and high weather resistance steels of different groups (%)
In table 1, the weather resistance index I is calculated as follows:
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 ，
wherein, (% Cu) is Cu content, (% Ni) is Ni content, (% Cr) is Cr content, (% Si) is Si content, and (% P) is P content.
The calculation result of the weather resistance index I is that I is more than or equal to 8.0.
The calculation formula of the composite factor index T is as follows:
T＝[5(％P)+(％Cu)+(％Cr)/3+0.1(％Si)+0.1(％Al)]/[4(％C)+0.5(％Mn)]，
wherein, (% P) is the content of P, (% Cu) is the content of Cu, (% Cr) is the content of Cr, (% Si) is the content of Si, (% Al) is the content of Al, (% C) is the content of C, and (% Mn) is the content of Mn.
The calculation result of the comprehensive factor index T is that T is more than or equal to 2.3.
(2) And (3) heating a plate blank: in the preheating section, a strong oxidizing atmosphere with an air excess coefficient alpha of 1.40-1.50 is adopted, and the mixture is rapidly heated to be more than or equal to 850 ℃ at a heating rate of 16-19 ℃/min;
in the heating stage, a weak oxidizing atmosphere with an air excess coefficient alpha 1 of (1.15-0.025 h) is adopted, and the furnace is quickly heated to a temperature T1=tapping temperature (0.936-0.013 h+0.0020h) 2 )；
In the second heating stage, a weak oxidizing atmosphere with an air excess coefficient alpha 2 of (1.13-0.027 h) is adopted, and the furnace is quickly heated to a temperature T2=tapping temperature (1.016-0.015 h+0.0018 h) 2 )；
And in the soaking section, a weak oxidizing atmosphere with an air excess coefficient alpha 3 of (1.11-0.029 h) is adopted, the furnace is quickly heated to a tapping temperature T= (1262-8.33 h) DEG C, the soaking time is 51-59 min, wherein h is the thickness of hot-rolled high-strength high-weather-resistant steel, mm, the total heating time T above 1100 ℃ is required to be (135-3.10 h) min and more than or equal to 110min, the sufficient austenitization is realized, the dissolution of microalloying elements and the sufficient diffusion of a liquid copper-rich phase at the interface of the iron sheet and the steel matrix are ensured, and the heating process is shown in table 2.
TABLE 2 heating process parameters
(3) And (3) hot rolling: in order to reduce the harmful effect of austenite grain boundary liquid copper-rich phase on the surface of the steel substrate, rough rolling adopts a 3+3 mode, rough rolling R1 adopts three times of rolling, rough rolling R2 adopts three times of rolling, the total reduction ratio of R1 three times is 32.2% -34.9%, the total reduction ratio of R1 three times is the first, second and third times of descaling, and the total reduction ratio of R2 three times is the ratio
49.3% -51.9% and R2 is descaled by adopting the first and third times; meanwhile, the outlet temperature of the rough rolling R2 is controlled below 1085 ℃ of the melting point of the liquid copper-rich phase, namely 1061 ℃ to 1079 ℃; the finish rolling is carried out continuously by adopting 6-7 frames, the lower finish rolling finishing temperature is 826-848 ℃, and the hot rolling process is shown in table 3.
TABLE 3 soaking and Rolling Process parameters
(4) Cooling after rolling: after rolling, adopting an ultra-fast cooling and laminar cooling mode, wherein the cooling water pressure is 0.37-0.39 MPa, the ultra-fast cooling outlet temperature is 625-639 ℃, and the ultra-fast cooling speed range is 51-79 ℃/s; and after ultra-fast cooling, performing laminar cooling, adopting edge shielding and U-shaped coiling, wherein the edge shielding width is 210-240 mm, the coiling temperature of the strip steel body is controlled at 555-575 ℃, the coiling temperature of the strip steel head and tail is 0-15 m higher than that of the body by 30 ℃, the coiling temperature of the strip steel head and tail is 16-30 m higher than that of the body by 20 ℃, the coiling temperature of the strip steel head and tail is 31-45 m higher than that of the body, and the specific cooling process parameters after rolling are shown in table 4.
Table 4 after-rolling cooling process parameters
Related experiment and effect data:
the hot-rolled high-strength high-weather-resistance steel obtained by each group is respectively detected on various mechanical properties and corrosion properties, wherein the corrosion properties are 0.01mol/L NaHSO with common carbon steel Q345B 3 The relative corrosion rates for 72-hour dip corrosion are set forth in Table 5.
TABLE 5 mechanical Properties and Corrosion resistance of Hot rolled high Strength high weathering Steel of each group
Examples 1/2 and 3 in Table 5 were not suitable for impact test because the thickness of the steel sheet was too thin, and thus only the steel sheet of example 4 was subjected to impact test.
As can be seen from Table 5, the yield strength of the hot rolled high strength and weather resistant steel of the present application is more than 700MPa, and up to 754MPa; the tensile strength is more than 800MPa, and the maximum tensile strength reaches 879MPa; the elongation after breaking is more than or equal to 18.0 percent, and the maximum elongation is 24.0 percent; meanwhile, 180 DEG d=a is qualified in transverse and longitudinal cold bending tests; impact energy at-40 ℃ (sample size 5 x 10 x 55 mm) is more than or equal to 47J, and corrosion rate is less than or equal to 37% relative to common structural steel Q345B; the hot-rolled high-strength high-weather-resistant steel obtained in the examples 1-4 is a metallographic structure of TiC nano-scale precipitates with quasi-polygonal ferrite and dispersion distribution, wherein nano-scale precipitates in ferrite are mainly precipitates with particle size distribution of 2-5 nm, and the ratio of the nano-scale precipitates to the ferrite is up to 88%.
One or more technical solutions in the embodiments of the present application at least further have the following technical effects or advantages: (1) The 700 MPa-level hot-rolled high-strength high-weather-resistant steel has a quasi-polygonal ferrite+dispersed TiC nano-scale precipitate organization structure, and the nano-scale precipitate phase in the ferrite is mainly precipitates with the particle size distribution of 2-5 nm and accounts for 88 percent; the yield strength can reach more than 700MPa, the tensile strength reaches more than 800MPa, the elongation after fracture reaches more than 18%, 180 DEG d=a is qualified in transverse bending, the impact energy at-40 ℃ is more than or equal to 47J, the fluctuation of the through-rolling yield strength is less than or equal to 65MPa, and the corrosion rate is less than or equal to 37% relative to the common structural steel Q345B.
(2) The 700 MPa-level hot-rolled high-strength high-weather-resistance steel has good plate shape, surface quality, cold formability, weldability and weather resistance, and can meet the processing and service performance requirements of a steel structure.
(3) The application provides a 700MPa grade hot rolling high strength high weather resistant steel, the railway vehicle that uses this high strength high weather resistant steel to make, container, photovoltaic support, highway guardrail, building scaffold etc. have excellent cold forming performance, welding performance and corrosion resistance, and can avoid the application in fields such as photovoltaic support, highway guardrail, building scaffold under the C1-C3 atmospheric environment, and its life reaches more than 23 years.
Various embodiments of the present application may exist in a range format; it should be understood that the description in a range format is merely for convenience and brevity and should not be interpreted as a rigid limitation on the scope of the application. It is therefore to be understood that the range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that a description of a range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, wherever applicable. In addition, whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the indicated range.
In this application, unless otherwise indicated, terms of orientation such as "upper" and "lower" are used specifically to refer to the orientation of the drawing in the figures. In addition, in the description of the present application, the terms "include", "comprise", "comprising" and the like mean "including but not limited to". Relational terms such as "first" and "second", and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Herein, "and/or" describing an association relationship of an association object means that there may be three relationships, for example, a and/or B, may mean: a alone, a and B together, and B alone. Wherein A, B may be singular or plural. Herein, "at least one" means one or more, and "a plurality" means two or more. "at least one", "at least one" or the like refer to any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
The foregoing is merely a specific embodiment of the application to enable one skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. The 700 MPa-grade hot-rolled high-strength high-weather-resistant steel is characterized by comprising the following chemical components in percentage by mass: c:0.043% -0.048%, si:0.51 to 0.59 percent, mn:0.61% -0.68%, P:0.041 to 0.049 percent, S:0.0031% -0.0038%, al:0.071% -0.079%, ti:0.092% -0.099%, cu:0.251% -0.259%, cr:1.81 to 1.98 percent, N:0.0031% -0.0034% and the balance of Fe and unavoidable impurities.
2. The hot-rolled high strength and high weather resistant steel according to claim 1, wherein the structure of the hot-rolled high strength and high weather resistant steel comprises ferrite and TiC nano-sized precipitates, wherein a nano-sized precipitated phase having a grain size of 2nm to 5nm in the ferrite accounts for 88% or more of the TiC nano-sized precipitates.
3. The hot rolled high strength and high weather resistant steel as claimed in claim 1, wherein the thickness h of the hot rolled high strength and high weather resistant steel is 1.2mm to 8.0mm.
4. A method of preparing a hot rolled high strength high weathering steel as defined in any one of claims 1 to 3, characterized in that the method comprises:
obtaining a cast slab comprising the same chemical composition as the hot rolled high strength high weathering steel according to any one of claims 1-3;
heating the casting blank, and then sequentially performing rough descaling and rough rolling to obtain an intermediate plate blank;
and (3) performing fine descaling, finish rolling, ultra-fast cooling and laminar cooling on the intermediate slab, and coiling to obtain the hot-rolled high-strength high-weather-resistance steel.
5. The method of claim 4, wherein the heating comprises a preheating section, a heating first section, a heating second section and a soaking section, wherein the heating rate of the preheating section is 16 ℃/min-19 ℃/min, and the temperature of the end of the preheating section is not less than 850 ℃;
the end temperature T1 of the heating section is as follows:
T1＝T*(0.936-0.013h+0.0020h 2 )；
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; t is the temperature of the heating furnace, and the temperature is DEG C; and/or the number of the groups of groups,
the section end temperature T2 of the heating two sections meets the following conditions:
T2＝T*(1.016-0.015h+0.0018h 2 )；
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; t is the furnace outlet temperature of heating, and the temperature is DEG C; and/or the number of the groups of groups,
the segment end temperature T of the soaking segment meets the following conditions:
T＝1262-8.33h；
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; t is the tapping temperature of the heating, and the temperature is DEG C.
6. The method according to claim 5, wherein the atmosphere of the preheating section is a strong oxidizing atmosphere, and the air excess coefficient α of the preheating section is 1.40 to 1.50; and/or the number of the groups of groups,
the atmosphere of the heating section is a weak oxidizing atmosphere, and the air excess coefficient alpha 1 of the heating section meets the following conditions:
α1＝1.15-0.025h，
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; and/or the number of the groups of groups,
the atmosphere of the heating second section is a weak oxidizing atmosphere, and the air excess coefficient alpha 2 of the heating second section meets the following conditions:
α2＝1.13-0.027h，
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm;
the atmosphere of the soaking section is a weak oxidizing atmosphere, and the air excess coefficient alpha 3 of the soaking section meets the following conditions:
α3＝1.11-0.029×h，
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm.
7. The method of claim 5, wherein the heating further comprises heating at a temperature above 1100 ℃ for a total heating time of greater than or equal to 110 minutes, wherein the total heating time t is:
t＝135-3.10h，
wherein h is the thickness of the hot-rolled high-strength high-weather-resistance steel, and mm; and/or the number of the groups of groups,
the time of the soaking section is 51-59 min.
8. The method of claim 5, wherein the rough rolling comprises a first rough rolling and a second rough rolling,
the total rolling reduction of the first rough rolling is 32.2-34.9%, the total rolling reduction of the second rough rolling is 49.3-51.9%, and the outlet temperature of the second rough rolling is 1061-1079 ℃; and/or the number of the groups of groups,
the finish rolling comprises the step of adopting a continuous finish rolling mode to finish rolling, wherein the outlet temperature of the finish rolling is 826-848 ℃.
9. The method according to claim 4, wherein the ultra-fast cooling comprises cooling by means of ultra-fast water cooling water, wherein the pressure of the ultra-fast cooling is 0.37-0.39 MPa, the outlet temperature of the ultra-fast cooling is 625-639 ℃, and the speed of the ultra-fast cooling is 51-79 ℃/s; and/or the number of the groups of groups,
the laminar cooling is carried out by adopting a mode of shielding hot rolled strip steel at the edge, and the width of the edge shielding is 210-240 mm; and/or the number of the groups of groups,
the coiling comprises coiling in a step-type U-shaped temperature mode of controlling the temperature of the finished strip steel body and the temperature of the head and the tail of the strip steel, wherein the coiling temperature of the strip steel body is 555-575 ℃; and/or the number of the groups of groups,
the coiling temperature at the position 0-15 m away from the head and the tail of the strip steel is 585-605 ℃; and/or the number of the groups of groups,
the coiling temperature at the position 16 m-30 m away from the head and the tail of the strip steel is 575-595 ℃; and/or the number of the groups of groups,
the coiling temperature at the position 31 m-45 m away from the head and the tail of the strip steel is 565-585 ℃.
10. Use of a hot rolled high strength high weathering steel as claimed in any of the claims 1-3, characterized in that the use comprises: use of the hot rolled high strength high weathering steel as defined in any one of claims 1 to 3 in a coating free steel structure in a C1 to C3 atmosphere.
CN202310477994.5A 2023-04-28 2023-04-28 700 MPa-grade hot-rolled high-strength high-weather-resistance steel and preparation method and application thereof Pending CN116497280A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118653093A (en) * 2024-08-16 2024-09-17 北京科技大学 800 MPa-grade rare earth composite Nb and Ti microalloyed high-strength weathering steel and preparation method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118653093A (en) * 2024-08-16 2024-09-17 北京科技大学 800 MPa-grade rare earth composite Nb and Ti microalloyed high-strength weathering steel and preparation method thereof

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