Production and preparation method of low-cost high-strength SY390 steel sheet pile

Abstract

The invention discloses a production and preparation method of a low-cost high-strength SY390 steel sheet pile. The production and preparation method comprises a steelmaking process flow and a steel rolling process flow, the steel sheet pile comprises the following chemical components in percentage by mass: 0.20%-0.25% of C, 0.45%-0.50% of Si, 1.20%-1.30% of Mn, less than or equal to 0.018% of P, less than or equal to 0.015% of S, 0.02%-0.03% of V, more than or equal to 0.010% of Al, 0.010%-0.012% of N and the balance of Fe and other trace impurity elements. Through reasonable chemical component design and production process control, the strength and plasticity of the steel sheet pile can be effectively improved, the steel sheet pile can be repeatedly used, and the performance of the steel sheet pile meets the requirements that the yield strength is larger than or equal to 390 MPa, the tensile strength is larger than or equal to 490 MPa, and the ductility is larger than or equal to 21%.

Description

Technical Field

[0001] The invention belongs to the technical field of material metallurgy, and in particular relates to a production method for low-cost and high-strength SY390 steel sheet piles. Background Art

[0002] Steel sheet piles are essential for water conservancy project construction, cofferdam construction, tunnel construction, roadbed engineering, and bridge foundation engineering. Steel sheet piles have the following advantages: high quality (high strength, light weight, good water-proofing); simple construction, short construction period, and low construction cost; good durability, with a service life of 20-50 years; the use of steel sheet piles is not restricted by weather conditions, and in the process of using steel sheet piles, the complex procedures for checking material or system performance can be simplified; good interchangeability, can be reused 3-5 times, can be recycled and reused, and save money; construction has a significant environmental protection effect, greatly reducing the amount of soil and concrete used, and effectively protecting land resources; disaster relief has a strong timeliness, such as flood control, landslides, collapses, quicksand, etc.

[0003] The practical value of steel sheet piles is reflected in the innovative production of many new products, such as: some special welded buildings; metal plates made by hydraulic vibrating pile drivers; the development of special sealing and printing processes is a good example in this regard. For example, the HOESCH patented system has created an important new field for steel sheet piles in pollution control. Since steel sheet piles have been used as vertical sealed retaining walls to protect contaminated land, it has been found that steel sheet piles meet all requirements for preventing leakage and pollution. The advantages of steel sheet piles as retaining walls have gradually been widely used in other fields.

[0004] The document of Chinese patent application No. 202210700589.0 discloses "An Economical Hot-rolled U-shaped Sheet Piles Steel and Production Method", whose components and weight percentages are C: 0.24-0.30%, Si: 0.20-0.30%, Mn: 0.8-1.30%, Nb: 0.007-0.011%, P≤0.035%, S≤0.035%, and the rest is Fe and unavoidable impurities. The production process is converter-refining-continuous casting-rolling, and its chemical composition range is wide, but the introduction of production process parameters is relatively small, and the operability is not strong.

[0005] The document of Chinese patent application No. 201910559462.X discloses "Hot-rolled steel sheet pile and its production method", whose components and weight percentages are: C 0.21-0.50%, Si≤0.17%, Mn 0.7-0.99%, P≤0.030%, S≤0.030%, and the rest is Fe and unavoidable impurities. Its yield strength is low, the chemical composition range is wide, and the production process is complicated, which is not conducive to guiding actual production.

[0006] The document of Chinese patent application No. 201010147762.6 discloses "Steel for hot-rolled U-shaped steel sheet pile with tensile strength ≥ 600MPa and its production method", whose components and weight percentages are C: 0.31-0.50%, Mn: 1.0-2.0%, Si: 0.10-0.60%, P≤0.02%, S≤0.02%, TAl: 0.01-0.06%, Nb: 0.015-0.035%, Ti: 0.005-0.030%. The rest is Fe and unavoidable impurities. Its chemical composition is complex, the alloy cost is high, and the high Al element is not conducive to continuous casting production. Summary of the invention

[0007] The purpose of the present invention is to provide a low-cost and high-strength SY390 steel sheet pile production and preparation method. The present invention can effectively improve the strength and plasticity of the steel sheet pile through reasonable chemical composition design and production process control, so that the steel sheet pile can be reused many times, and its performance meets the following requirements: yield strength ≥390MPa, tensile strength ≥490MPa, and elongation ≥21%.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] The present invention discloses a method for producing and preparing SY390 steel sheet piles with low cost and high strength. The steelmaking process includes: molten iron - molten iron pretreatment - converter - refining outside the furnace - rectangular billet continuous casting; the steel rolling process includes: walking beam heating furnace - high-pressure water dephosphorization - BD primary rolling - CCS finishing rolling - cooling - straightening - sawing - inspection - bundling - storage. The method is characterized in that the technical parameters controlled in the steelmaking process are:

[0010] Use VN alloy with V, N element percentage ≥ 0.01%;

[0011] Continuous casting superheat ≤30℃;

[0012] Casting machine pulling speed 0.60m / min~0.62m / min;

[0013] Crystallizer cooling water temperature ≥26℃;

[0014] The technical parameters controlled in the rolling process are:

[0015] 1) Heating temperature 1220-1250℃, insulation time ≥ 3 hours;

[0016] 2) Rolling temperature ≤ 1150℃;

[0017] 3) Final rolling temperature ≤ 870℃;

[0018] The chemical composition of the steel sheet pile is as follows: C: 0.20%-0.25%, Si: 0.45%-0.50%, Mn: 1.20%-1.30%, P≤0.018%, S≤0.015%, V: 0.02%-0.03%, Al: ≥0.010%, N: 0.010%-0.012%, and the rest are Fe and other trace impurity elements.

[0019] Furthermore, the chemical composition of the steel sheet pile is as follows: C: 0.22%, Si: 0.47%, Mn: 1.23%, P: 0.018%, S: 0.010%, V: 0.029%, Al: 0.012%, N: 0.0105%, and the rest are Fe and other trace impurity elements.

[0020] Furthermore, the chemical composition of the steel sheet pile is as follows: C: 0.23%, Si: 0.46%, Mn: 1.25%, P: 0.014%, S: 0.011%, V: 0.026%, Al: 0.012%, N: 0.0115%, and the rest are Fe and other trace impurity elements.

[0021] Furthermore, the chemical composition of the steel sheet pile is as follows: C: 0.22%, Si: 0.46%, Mn: 1.28%, P: 0.015%, S: 0.009%, V: 0.025%, Al: 0.011%, N: 0.0108%, and the rest are Fe and other trace impurity elements.

[0022] Furthermore, the steel rolling process parameters are: heating temperature 1240°C.

[0023] Furthermore, the steel rolling process parameters are: heating time 3.5h.

[0024] Furthermore, the steel rolling process parameters are: starting rolling temperature 1095-1130 degrees Celsius, and final rolling temperature 845-859℃.

[0025] The functions of some elements in the steel of the present invention are as follows:

[0026] C: It is the main element that determines the strength of steel and the main substance that forms pearlite. The form and amount of carbides in steel determine the hardness and strength of steel. That is, as the C content increases, the strength and hardness of steel increase, while the plasticity and toughness of steel decrease. Therefore, the C content should not be too high, and carbon is the most effective element for improving strength, so the C content should not be too low. Therefore, the C content is controlled within the range of 0.20-0.22%.

[0027] Si: It can improve the corrosion resistance of steel and is often added to stainless steel, low alloy steel, and corrosion-resistant alloys to improve the corrosion resistance of these alloys, so that they have the properties of resistance to chloride stress corrosion cracking, pitting corrosion, hot concentrated nitric acid corrosion, oxidation resistance, and seawater corrosion resistance. Studies have shown that in a hot and humid atmospheric environment, Si can significantly improve the atmospheric corrosion resistance of carbon steel and low alloy steel. In addition, Si can also improve the corrosion resistance of low alloy steel in the splash zone of seawater. The Si element content of the steel of the present invention is designed to be 0.45-0.55%.

[0028] Mn: It is an important strengthening element with low composition. With the increase of manganese content, the strength of steel is significantly improved, the processing performance of steel is improved, and the tough-brittle transition temperature hardly changes. However, if the manganese content is too high, it will inhibit the transformation of ferrite, affect the yield strength of steel, and be unfavorable for the control of yield strength ratio. The Mn element content of the steel of the present invention is designed to be 1.20-1.30%.

[0029] P and S are impurity elements in steel. P has a certain effect of improving corrosion resistance, but P is an element that is easy to segregate. It will cause serious segregation in parts of the steel, reduce plasticity and toughness, and is extremely harmful to low-temperature toughness. The S element is easy to segregate and enrich in steel, and is an element that is harmful to corrosion resistance. The steel of the present invention strictly controls the sulfur and phosphorus content levels in terms of metallurgical quality, that is, P: ≤0.018%, S: ≤0.015% to meet the requirements of steel grade for purity, impact toughness, welding performance and corrosion resistance.

[0030] V: V has a strong bonding ability with C, O, and N, and forms extremely stable compounds with them, thereby refining the grains, reducing the thermal sensitivity and temper brittleness of steel. It can significantly improve the welding performance of ordinary low-alloy steel. The V content of the steel of the present invention is designed to be 0.02-0.03%.

[0031] Al: Al has a strong affinity with O and N, and is a deoxidizing and nitrogen fixing agent during steelmaking. Aluminum can strongly reduce the austenite phase region in steel, refine the intrinsic grain size of steel, reduce the notch sensitivity of steel, reduce and eliminate the aging phenomenon of steel, especially reduce the toughness-brittleness transition temperature of steel, and improve the low-temperature toughness of steel. However, when the solid-solution Al content in steel exceeds a certain value, the austenite grains tend to grow and coarsen. The Al element content of the steel of the present invention is designed to be ≥0.010%.

[0032] N: Nitrogen can dissolve in steel to form a solid solution. In addition, nitrogen can also form nitrides in steel, which preferentially nucleate in steel and increase the dislocation of ferrite, which can effectively increase the strength and toughness of steel. The N content of the steel of the present invention is designed to be 0.010-0.012%.

[0033] Compared with the prior art, the beneficial technical effects of the present invention are:

[0034] 1) The chemical composition range is more accurate, and low-carbon micro-alloying is used to produce steel sheet piles, which is simple to operate and easy to produce.

[0035] 2) The cost of VN microalloying is lower than that of VFe microalloying. Adding a small amount of Al can fix the N element in the air and improve the strength and plasticity of the steel sheet pile. DETAILED DESCRIPTION

[0036] The present invention is further described below by means of specific examples. The examples are only for the purpose of explanation, and the protection scope of the present invention is not limited to these examples.

[0037] The present invention will be further described below:

[0038] Table 1 and Table 2 show the weight percentage content of chemical components and carbon equivalent and steelmaking process parameters of various embodiments of the present invention.

[0039] Table 1 Chemical composition and weight percentage content of the examples

[0040]

[0041]

[0042] Table 2 shows the steelmaking process parameters

[0043]

[0044] Tables 3 and 4 show the rolling process parameters and the mechanical properties test data of SY390.

[0045] Table 3 Steel rolling process parameters

[0046] Example Heating temperature(℃) Heating time (h) Rolling temperature (℃) Finishing rolling temperature(℃) 1 1240 3.5 1095 856 2 1240 3.5 1100 859 3 1240 3.5 1130 845

[0047] Table 4 Mechanical properties of SY390.

[0048] Example Yield strength / MPa Tensile strength / MPa Elongation / % 1 473 619 24 2 486 628 23 3 461 610 24

[0049] It can be seen from Table 1 that the chemical composition and steelmaking process of Examples 1 and 2 are within the scope required by the patent of the present invention, and the smelting composition is well controlled.

[0050] Through the test data analysis in Table 3 and Table 4 and the rolling process, all performance indicators meet the technical requirements.

[0051] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A low-cost and high-strength SY390 steel sheet pile production and preparation method, steelmaking process: molten iron - molten iron pretreatment - converter - refining outside the furnace - rectangular billet continuous casting, steel rolling process: walking beam heating furnace - high-pressure water dephosphorization - BD initial rolling - CCS finishing rolling - cooling - straightening - sawing - inspection - bundling - storage, characterized by: The technical parameters controlled in the steelmaking process are: Use VN alloy with V, N element percentage ≥ 0.01%; Continuous casting superheat ≤30℃; Casting machine pulling speed 0.60m / min~0.62m / min; Crystallizer cooling water temperature ≥26℃; The technical parameters controlled in the rolling process are: 1) Heating temperature 1220-1250℃, insulation time ≥ 3 hours; 2) Rolling temperature ≤ 1150℃; 3) Final rolling temperature ≤ 870℃; The chemical composition of the steel sheet pile is as follows: C: 0.20%-0.25%, Si: 0.45%-0.50%, Mn: 1.20%-1.30%, P≤0.018%, S≤0.015%, V: 0.02%-0.03%, Al: ≥0.010%, N: 0.010%-0.012%, and the rest are Fe and other trace impurity elements.

2. The low-cost and high-strength SY390 steel sheet pile production and preparation method according to claim 1 is characterized in that: The chemical composition of the steel sheet pile is as follows: C: 0.22%, Si: 0.47%, Mn: 1.23%, P: 0.018%, S: 0.010%, V: 0.029%, Al: 0.012%, N: 0.0105%, and the rest are Fe and other trace impurity elements.

3. The low-cost and high-strength SY390 steel sheet pile production and preparation method according to claim 1 is characterized in that: The chemical composition of the steel sheet pile is as follows: C: 0.23%, Si: 0.46%, Mn: 1.25%, P: 0.014%, S: 0.011%, V: 0.026%, Al: 0.012%, N: 0.0115%, and the rest are Fe and other trace impurity elements.

4. The low-cost and high-strength SY390 steel sheet pile production and preparation method according to claim 1 is characterized in that: The chemical composition of the steel sheet pile is as follows: C: 0.22%, Si: 0.46%, Mn: 1.28%, P: 0.015%, S: 0.009%, V: 0.025%, Al: 0.011%, N: 0.0108%, and the rest are Fe and other trace impurity elements.

5. The low-cost and high-strength SY390 steel sheet pile production and preparation method according to claim 1 is characterized in that: Steel rolling process parameters: heating temperature 1240℃.

6. The method for producing and preparing low-cost and high-strength SY390 steel sheet piles according to claim 5, characterized in that: Steel rolling process parameters: heating time 3.5h.

7. The method for producing and preparing low-cost and high-strength SY390 steel sheet piles according to claim 6, characterized in that: Steel rolling process parameters: starting rolling temperature 1095-1130 degrees Celsius, final rolling temperature 845-859℃.

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