CN110592486A - Niobium-containing 550 MPa-grade thick weathering resistant steel and production method thereof - Google Patents

Niobium-containing 550 MPa-grade thick weathering resistant steel and production method thereof Download PDF

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CN110592486A
CN110592486A CN201911000213.3A CN201911000213A CN110592486A CN 110592486 A CN110592486 A CN 110592486A CN 201911000213 A CN201911000213 A CN 201911000213A CN 110592486 A CN110592486 A CN 110592486A
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steel
equal
niobium
weathering steel
rolling
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崔凯禹
李正荣
汪创伟
熊雪刚
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Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
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Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
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    • 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
    • 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
    • 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
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese

Abstract

The invention belongs to the technical field of hot continuous rolling strip production, and particularly relates to niobium-containing 550 MPa-grade thick weathering steel and a production method thereof. Aiming at the existing market demands, the invention develops high-strength thick weathering steel with brand-new components and a production method thereof. The niobium-containing 550 MPa-grade thick weathering steel comprises the following components: c, according to weight percentage: 0.06-0.08%, Si: 0.25 to 0.35%, Mn: 1.55-1.70%, P is less than or equal to 0.018%, S is less than or equal to 0.007%, Cu: 0.20-0.30%, Cr: 0.32 to 0.42%, Ni: 0.12-0.20%, Nb: 0.055-0.065%, Als: 0.015 to 0.050% and the balance of Fe and inevitable impurities. The preparation method comprises the following steps: smelting, hot rolling, laminar cooling and coiling. According to the invention, the weather resistance of the steel is improved through component design, the existing hot continuous rolling unit can be adopted to realize the production of the weather-resistant steel with the thickness of 12-16 mm under the component, the operation is simple, the production cost is low, and the comprehensive performance of the prepared product is excellent.

Description

Niobium-containing 550 MPa-grade thick weathering resistant steel and production method thereof
Technical Field
The invention belongs to the technical field of hot continuous rolling strip production, and particularly relates to niobium-containing 550 MPa-grade thick weathering steel and a production method thereof.
Background
Weathering steel, also known as atmospheric corrosion resistant steel, is a low alloy steel with good corrosion resistance in the atmosphere. The weathering steel contains less than 0.2 wt% of C, and Cu, Cr, Ni, P, Si, Mn, etc. as main alloying elements. A great deal of research shows that the weathering steel shows good weathering performance, mainly because the weathering steel is exposed to the atmosphere for a long time, a layer of compact oxidation products with good adhesion is generated on the surface, so that a steel matrix is isolated from external corrosive substances, and the corrosion resistance of the weathering steel is obviously improved. The weathering steel is mainly applied to railway vehicles, the railway vehicles are continuously subjected to atmospheric corrosion and dynamic load abrasion action when in use, and the steel used in the severe working condition environment has the characteristics of high reliability, long service life, light weight, low cost and the like. With the development of modern railway construction and the continuous improvement of high-speed and heavy-load requirements, the body materials of railway vehicles are also developed from low-strength common carbon steel and low-strength weathering steel to high-strength weathering steel. For manufacturing vehicle parts, containers and other mobile equipment, the high-strength weathering steel is adopted to enhance weight reduction, so that the production cost of products can be reduced, the effective load can be improved, and the energy consumption can be reduced. Therefore, the application of the high-strength weathering steel (the yield strength is more than or equal to 450MPa) is more and more extensive.
Patent CN103305760A discloses a method for manufacturing a 550 MPa-grade high-strength weather-resistant steel by strip continuous casting, which comprises the following chemical components in percentage by weight: 0.03-0.08%, Si is less than or equal to 0.4%, Mn: 0.6-1.5%, P: 0.07-0.22%, S is less than or equal to 0.01%, N is less than or equal to 0.012%, Cu: 0.25 to 0.80%, and further comprises at least one of Nb, V, Ti, and Mo, wherein Nb: 0.01-0.08%, V: 0.01-0.08%, Ti: 0.01 to 0.08%, Mo: 0.1-0.4%, and the balance of Fe and inevitable impurities. The weathering steel in the patent is produced by adopting a thin slab continuous casting and rolling process, and the thickness of a casting blank is greatly reduced (the thickness is 50-90 mm). Therefore, the casting blank can be obtained only by 1-2 times of rough rolling or without rough rolling. In addition, the casting blank produced by the process can directly enter a soaking pit furnace for soaking and heat preservation without cooling, or a small amount of temperature supplement can be carried out, so that the process flow can be greatly shortened. Meanwhile, the solidification and cooling speed of the casting blank is accelerated under the process condition, and the element macrosegregation can be reduced to a certain extent, so that the content range of elements such as P, Cu of the weathering steel can be properly widened. In addition, the thickness of the weathering steel rolled by the method is 1-3 mm, the weathering steel is thin strip steel, and the method has no revelation effect on the rolling process of thick strip steel. Therefore, the method has certain limitation in use, and the components and the process of the method cannot be used for reference in the rolling of thick-specification steel plates in the traditional hot continuous rolling production.
Patent CN108251737A discloses a method for manufacturing high-strength weathering steel with yield strength of 550MPa grade, the alloy components and weight percentage content of the weathering steel are as follows: c: 0.03-0.08%, Si is less than or equal to 0.15%, Mn: 0.70-1.40%, P is less than or equal to 0.020%, S is less than or equal to 0.008%, Alt: 0.020-0.050%, N is less than or equal to 0.006%, and Cu: 0.20-0.55%, Cr: 0.30-0.60%, Ni: 0.04-0.20%, Ti: 0.05 to 0.09 percent of the total weight of the alloy, and the balance of Fe and inevitable trace elements. The weathering steel of the patent has higher Ti content, and TiN, TiC and Ti exist in Ti microalloyed steel4C2S2And the formation of a large amount of precipitates is present in each stage from continuous casting to coiling. The liquated TiN is micron-sized particles and can generate adverse effect on the performance of steel; TiN and T precipitated in solid statei4C2S2The size is also larger, and the strengthening effect is not obvious. It therefore has high requirements for ingredient and process stability control.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: develops a high-strength thick weathering steel with brand-new components and excellent performance and a production method thereof.
The technical scheme for solving the technical problems comprises the following steps: provides a thick weathering steel containing niobium 550 MPa. The niobium-containing 550 MPa-grade thick weathering steel comprises the following chemical components: c, according to weight percentage: 0.06-0.08%, Si: 0.25 to 0.35%, Mn: 1.55-1.70%, P is less than or equal to 0.018%, S is less than or equal to 0.007%, Cu: 0.20-0.30%, Cr: 0.32 to 0.42%, Ni: 0.12-0.20%, Nb: 0.055-0.065%, Als: 0.015 to 0.050% and the balance of Fe and inevitable impurities.
The yield strength of the weathering steel is more than or equal to 550MPa, the tensile strength is more than or equal to 600MPa, the elongation is more than or equal to 18%, the impact energy at minus 40 ℃ is more than or equal to 60J in a 180-degree cold bending test D-2 a, and the relative corrosion rate is less than or equal to 55%.
In the niobium-containing 550 MPa-grade thick weathering steel, the thick weathering steel is 12-16 mm thick weathering steel.
The invention also provides a production method of the niobium-containing 550 MPa-grade thick weathering steel, which comprises the following steps:
a. smelting the molten steel into a steel billet; the molten steel comprises the following components: c, according to weight percentage: 0.06-0.08%, Si: 0.25 to 0.35%, Mn: 1.55-1.70%, P is less than or equal to 0.018%, S is less than or equal to 0.007%, Cu: 0.20-0.30%, Cr: 0.32 to 0.42%, Ni: 0.12-0.20%, Nb: 0.055-0.065%, Als: 0.015 to 0.050% and the balance of Fe and inevitable impurities;
b. b, carrying out hot rolling on the steel billet smelted in the step a, wherein the tapping temperature before the hot rolling is 1220-1260 ℃, carrying out rough rolling for 5 times, the deformation of each time is more than or equal to 20%, carrying out full-length descaling, the initial rolling temperature of finish rolling is less than or equal to 960 ℃, and the final rolling temperature is 820-860 ℃;
c. performing sparse cooling after hot rolling;
d. and coiling the cooled steel at the coiling temperature of 560-600 ℃ to obtain the niobium-containing 550 MPa-grade thick weathering steel.
In the production method of the niobium-containing 550 MPa-grade thick weathering steel, the number of the cooling water racks opened in the step b finish rolling is more than or equal to 5.
In the production method of the niobium-containing 550 MPa-grade thick weathering steel, the boiling water rates of the upper header pipe and the lower header pipe which are opened in the sparse cooling in the step c are respectively 60% and 90%.
The invention has the beneficial effects that:
the invention develops the high-strength weathering steel with brand new components, a certain amount of Nb is introduced into the steel components, and the effect of Nb element fine grain strengthening is fully exerted; meanwhile, a proper amount of Cu, Cr and Ni elements are added, so that the corrosion resistance of the product is improved. Aiming at the steel with specific components, the invention also provides a specific production method, the uniformity of the structure in the thickness direction of the strip steel is improved through a controlled rolling and cooling process, the production of high-strength thick weathering steel on a hot continuous rolling mill set is realized, and finally 550 MPa-grade thick weathering steel is obtained, the yield strength of the steel is more than or equal to 550MPa, the tensile strength of the steel is more than or equal to 600MPa, the elongation of the steel is more than or equal to 18 percent, the 180-degree cold bending test D is 2a, the impact power at minus 40 ℃ is more than or equal to 60J, the relative corrosion rate is less than or equal to 55 percent, the strength is high, the corrosion resistance is strong, the structure is uniform, and the steel is suitable for being.
Detailed Description
The invention provides niobium-containing 550 MPa-grade thick weathering steel which comprises the following chemical components in percentage by weight: c: 0.06-0.08%, Si: 0.25 to 0.35%, Mn: 1.55-1.70%, P is less than or equal to 0.018%, S is less than or equal to 0.007%, Cu: 0.20-0.30%, Cr: 0.32 to 0.42%, Ni: 0.12-0.20%, Nb: 0.055-0.065%, Als: 0.015 to 0.050% and the balance of Fe and inevitable impurities.
C is an effective strengthening element in steel, can be dissolved into a matrix to play a role in solid solution strengthening, can be combined with V, Nb to form carbide precipitated particles to play a role in fine grain strengthening and precipitation strengthening, improves the carbon content, and is favorable for improving the strength, but too high carbon content can form more large and thick brittle carbide particles in the steel, is unfavorable for plasticity and toughness, and too high carbon content can form a segregation zone in the center of the steel plate, is unfavorable for bending performance formability, and simultaneously, too high carbon content increases welding carbon equivalent, and is unfavorable for welding processing. Thus, design C of the present invention: 0.06-0.08%.
Si has higher solid solubility in steel, is beneficial to thinning rust layer tissues, reduces the integral corrosion rate of the steel and improves the toughness, but the scale removal is difficult during rolling due to the over-high content, and the welding performance is reduced. Therefore, the invention designs Si: 0.25 to 0.35 percent.
Mn has a strong solid solution strengthening effect, can obviously reduce the phase transition temperature of steel, refines the microstructure of the steel, is an important toughening element, but easily produces casting blank cracks in the continuous casting process when the content of Mn is excessive, and simultaneously can reduce the welding performance of the steel. Therefore, the invention designs Mn: 1.55 to 1.70 percent.
P can effectively improve the atmospheric corrosion resistance of steel, and when P and Cu are jointly added into the steel, a better composite effect can be displayed, but the plasticity and the low-temperature toughness of the steel are obviously reduced when the content of P is too high. Therefore, the design P is less than or equal to 0.018 percent.
S can form sulfide inclusions to deteriorate the performance of steel, and meanwhile, pitting corrosion expansion is easy to form in the corrosion process, and the corrosion performance is adversely affected. Therefore, S is less than or equal to 0.007 percent in the design.
The addition of Cu is favorable for forming a compact amorphous oxide (alkyl oxide) protective layer with good adhesion on the surface of steel, and the corrosion resistance is more obvious. In addition, Cu forms insoluble sulfides with S, thereby counteracting the deleterious effects of S on steel corrosion resistance. However, if the Cu content is too high, cracks are likely to occur during heating or hot rolling. Therefore, the present invention designs Cu: 0.20 to 0.30 percent.
Cr has an obvious effect of improving the passivation capability of steel, can promote the surface of the steel to carry out a compact passivation film or a protective rust layer, and the enrichment of Cr in the rust layer can effectively improve the selective permeability of the rust layer to corrosive media. However, too high Cr content increases the production cost. Therefore, the invention designs Cr: 0.32 to 0.42 percent.
While Ni can significantly improve the low-temperature toughness of steel and effectively prevent the hot brittleness of Cu, Ni is a precious metal element, and too high Ni increases the adhesion of scale, and hot rolling defects are formed on the surface when pressed into steel. Therefore, the present invention designs Ni: 0.12 to 0.20 percent.
Nb can pin austenite grain boundaries to prevent grain growth and finally refine grains, but the content is too high to be beneficial to the welding performance of steel, and the production cost is increased. The present invention therefore designs Nb: 0.055-0.065%.
Al plays a role in deoxidation when added into steel, but the content of Al is too high, and nitrogen oxides are easy to precipitate at austenite grain boundaries to cause casting blank cracks to be generated. Therefore, the invention designs Als: 0.015-0.050%.
The invention particularly designs high-strength thick weathering steel, which has the advantages that the strength can meet the requirements of the existing industrial standards and the weather resistance of steel is improved by limiting the components such as C, Si, Mn, P, S, Cu and the like in a reasonable range and adding certain contents of alloy components such as Cr, Ni, Nb and the like.
In the high-strength thick weathering steel prepared by the invention, the yield strength of the thick weathering steel containing niobium and with the grade of 550MPa is more than or equal to 550MPa, the tensile strength is more than or equal to 600MPa, the elongation is more than or equal to 18%, the impact energy at minus 40 ℃ is more than or equal to 60J in a 180-degree cold bending test D-2 a, and the relative corrosion rate (relative to Q345B) is less than or equal to 55%.
In the niobium-containing 550 MPa-grade thick weathering steel, the thick weathering steel is 12-16 mm thick weathering steel.
Aiming at the thick weathering steel with specific components, the invention provides a production method of the thick weathering steel containing niobium and 550MPa, which comprises the following steps:
a. smelting the molten steel into a steel billet; the molten steel comprises the following components: c, according to weight percentage: 0.06-0.08%, Si: 0.25 to 0.35%, Mn: 1.55-1.70%, P is less than or equal to 0.018%, S is less than or equal to 0.007%, Cu: 0.20-0.30%, Cr: 0.32 to 0.42%, Ni: 0.12-0.20%, Nb: 0.055-0.065%, Als: 0.015 to 0.050% and the balance of Fe and inevitable impurities;
b. b, carrying out hot rolling on the steel billet smelted in the step a, wherein the tapping temperature before the hot rolling is 1220-1260 ℃, carrying out rough rolling for 5 times, the deformation of each time is more than or equal to 20%, carrying out full-length descaling, the initial rolling temperature of finish rolling is less than or equal to 960 ℃, and the final rolling temperature is 820-860 ℃;
c. performing sparse cooling after hot rolling;
d. and coiling the cooled steel at the coiling temperature of 560-600 ℃ to obtain the niobium-containing 550 MPa-grade thick weathering steel.
In the production method of the niobium-containing 550 MPa-grade thick weathering steel, the number of the cooling water racks opened in the step b finish rolling is more than or equal to 5.
In the production method of the niobium-containing 550 MPa-grade thick weathering steel, the water boiling rates of the upper and lower cooling water collecting pipes in the cooling of the step c are respectively 60% and 90%.
In the production method, in the hot rolling procedure, the high heating temperature is adopted to play a role in homogenizing the composition segregation of the as-cast structure, but the problems of burning loss, overheating, overburning and the like can occur when the heating temperature is too high; the rough rolling needs to reach enough deformation to ensure austenite recrystallization, refine austenite grains and prevent mixed crystal tissues, and the rough rolling is full-length and full-line descaling to fully remove iron scales so as to avoid the surface quality problem caused by pressing of the iron scales; if the initial rolling temperature of finish rolling is too high, the deformation of the non-recrystallization region of austenite in the finish rolling process is insufficient, and the structure is not refined; if the finish rolling temperature is too low, the difference between the finish rolling temperature and the initial rolling temperature is too large, so that the cooling speed in the finish rolling process is too high, the risk of rolling in a two-phase region by a plurality of racks after finish rolling exists, the comprehensive performance of a product is poor, and if the finish rolling temperature is too high, the cooling speed in the laminar cooling process is too large, so that an abnormal structure is generated. Thus, the present invention is finally determined by experiments: the tapping temperature before hot rolling is 1220-1260 ℃, the rough rolling is carried out for 5 times of rolling, the deformation of each time is more than or equal to 20%, the full-length descaling is carried out, the finish rolling starting temperature is less than or equal to 960 ℃, and the final rolling temperature is 820-860 ℃, so that the steel meeting the requirements can be obtained.
The invention adopts a sparse cooling mode during cooling, and the sparse cooling can reduce the temperature difference between the thickness center and the surface in the cooling process of thick-specification strip steel, thereby being beneficial to improving the uniformity of the structure in the thickness direction and further improving the comprehensive performance of the product. And cooling water between the racks is opened during finish rolling, so that the cooling speed of the strip steel in the finish rolling process can be increased, the rolling speed is increased on the basis of ensuring the start rolling temperature and the finish rolling temperature of the finish rolling, the difference between the finish cooling temperature and the coiling temperature of a laminar cooling section is reduced, and the product performance is ensured. The number of the cooling water racks opened during finish rolling is more than or equal to 5, and the water boiling rates of the upper and lower collecting pipes of the cooling water during laminar cooling are respectively 60% and 90%; this was obtained by the inventors through a number of experimental screens. The invention sets a difference value for the water boiling rate of the upper and lower collecting pipes, thus the cooling speed of the upper and lower collecting pipes is equal, and the cooled steel tissue is more uniform finally.
In the coiling process, if the coiling temperature is too low, the cooling speed in the laminar cooling process is too high, so that abnormal structures are generated, the coiling temperature is too high, so that the crystal grains are coarse, so that the comprehensive performance of a finished product is poor, and the coiling temperature is 560-600 ℃.
The following examples are given to further illustrate the embodiments of the present invention, but the scope of the present invention is not limited thereto.
Examples 1 and 2 preparation of niobium-containing 550 MPa-grade thick weathering steel by the method of the present invention
Examples the composition of the weathering steel is shown in table 1 below.
TABLE 1 composition/% of weathering steel of the examples
Numbering C Si Mn P S Cr Ni Cu Nb Als
Example 1 0.08 0.32 1.61 0.015 0.004 0.37 0.14 0.23 0.059 0.041
Example 2 0.08 0.30 1.65 0.016 0.003 0.36 0.15 0.23 0.059 0.039
The molten steel of the above composition is subjected to smelting, hot rolling, cooling and coiling. Wherein, the rough rolling in the hot rolling procedure is carried out for 5 times of rolling, the deformation of each time is more than or equal to 20 percent, the whole length of the rolling line is descaled for a whole number, and 5 frames of cooling water between the frames are opened. The specific process control is shown in table 2.
TABLE 2 examples weathering steel preparation parameters
Comparative examples 1 and 2 weathering steel without the preparation method of the invention
The composition of the comparative steel is shown in table 3 below.
TABLE 3 comparative example weathering steel composition%
The molten steel of the above composition is subjected to smelting, hot rolling, cooling and coiling. Wherein, the rough rolling in the hot rolling procedure is carried out for 5 times of rolling, the deformation of each time is more than or equal to 20 percent, the whole length of the rolling line is descaled for a whole number, and 5 frames of cooling water between the frames are opened. The specific process control is shown in table 4.
TABLE 4 comparative example weathering steel preparation parameters
The weathering steels prepared in the examples and comparative examples have the overall properties shown in Table 5.
TABLE 5 combination of properties of weathering steel prepared in examples and comparative examples
As can be seen from the examples and comparative examples, the invention develops a new component niobium-containing 550MPa thick weathering steel, which contains Cr, Ni, Nb and other alloy components, and improves the strength and weather resistance of the steel. The production process of the steel provided by the invention is reasonable in design, the existing hot continuous rolling mill set is adopted to realize the production of the weathering steel with the thickness of 12-16 mm, the operation is simple, the production cost is low, and the prepared product has excellent comprehensive performance and good application prospect.

Claims (6)

1. The niobium-containing 550 MPa-grade thick weathering steel is characterized by comprising the following chemical components: c, according to weight percentage: 0.06-0.08%, Si: 0.25 to 0.35%, Mn: 1.55-1.70%, P is less than or equal to 0.018%, S is less than or equal to 0.007%, Cu: 0.20-0.30%, Cr: 0.32 to 0.42%, Ni: 0.12-0.20%, Nb: 0.055-0.065%, Als: 0.015 to 0.050% and the balance of Fe and inevitable impurities.
2. The niobium-containing 550MPa grade thick gauge weathering steel of claim 1, characterized by: the yield strength of the weathering steel is more than or equal to 550MPa, the tensile strength is more than or equal to 600MPa, the elongation is more than or equal to 18 percent, the 180-degree cold bending test D is 2a, the impact energy at minus 40 ℃ is more than or equal to 60J, and the relative corrosion rate is less than or equal to 55 percent.
3. The niobium-containing 550MPa grade thick gauge weathering steel of claim 1, characterized by: the thick weathering steel is 12-16 mm thick weathering steel.
4. The method for producing the thick gauge weathering steel containing niobium 550MPa grade as claimed in any of claims 1 to 3, characterized by comprising the following steps:
a. smelting the molten steel into a steel billet; the molten steel comprises the following components: c, according to weight percentage: 0.06-0.08%, Si: 0.25 to 0.35%, Mn: 1.55-1.70%, P is less than or equal to 0.018%, S is less than or equal to 0.007%, Cu: 0.20-0.30%, Cr: 0.32 to 0.42%, Ni: 0.12-0.20%, Nb: 0.055-0.065%, Als: 0.015 to 0.050% and the balance of Fe and inevitable impurities;
b. b, carrying out hot rolling on the steel billet smelted in the step a, wherein the tapping temperature before the hot rolling is 1220-1260 ℃, carrying out rough rolling for 5 times, the deformation of each time is more than or equal to 20%, carrying out full-length descaling, the initial rolling temperature of finish rolling is less than or equal to 960 ℃, and the final rolling temperature is 820-860 ℃;
c. performing sparse cooling after hot rolling;
d. and coiling the cooled steel at the coiling temperature of 560-600 ℃ to obtain the niobium-containing 550 MPa-grade thick weathering steel.
5. The method for producing niobium-containing 550MPa grade thick gauge weathering steel of claim 4, wherein: and (b) opening cooling water racks in the finish rolling of the step b, wherein the number of the opened cooling water racks is more than or equal to 5.
6. The method for producing niobium-containing 550MPa grade thick gauge weathering steel of claim 4, wherein: and c, respectively controlling the water boiling rates of the upper header and the lower header to be 60% and 90% when the water is sparsely cooled in the step c.
CN201911000213.3A 2019-10-21 2019-10-21 Niobium-containing 550 MPa-grade thick weathering resistant steel and production method thereof Pending CN110592486A (en)

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Citations (5)

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CN101235469A (en) * 2008-02-28 2008-08-06 武汉钢铁(集团)公司 High-strength easy-formation atmospheric corrosion resisting steel
CN102168229A (en) * 2010-02-25 2011-08-31 宝山钢铁股份有限公司 Weather resistant steel plate and manufacturing method thereof
CN106521352A (en) * 2016-11-16 2017-03-22 攀钢集团攀枝花钢铁研究院有限公司 Niobium-containing heavy gauge weathering steel and rolling method thereof
CN107419191A (en) * 2017-08-16 2017-12-01 攀钢集团攀枝花钢铁研究院有限公司 Ultra-thin weathering steel and its production method
CN107841689A (en) * 2017-10-19 2018-03-27 南京钢铁股份有限公司 A kind of weather-resistant steel plate and its manufacture method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101235469A (en) * 2008-02-28 2008-08-06 武汉钢铁(集团)公司 High-strength easy-formation atmospheric corrosion resisting steel
CN102168229A (en) * 2010-02-25 2011-08-31 宝山钢铁股份有限公司 Weather resistant steel plate and manufacturing method thereof
CN106521352A (en) * 2016-11-16 2017-03-22 攀钢集团攀枝花钢铁研究院有限公司 Niobium-containing heavy gauge weathering steel and rolling method thereof
CN107419191A (en) * 2017-08-16 2017-12-01 攀钢集团攀枝花钢铁研究院有限公司 Ultra-thin weathering steel and its production method
CN107841689A (en) * 2017-10-19 2018-03-27 南京钢铁股份有限公司 A kind of weather-resistant steel plate and its manufacture method

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Application publication date: 20191220