Production method of hot-rolled H-shaped steel for ocean engineering structure

Abstract

The invention discloses a production method of hot-rolled H-shaped steel for an ocean engineering structure. The hot-rolled H-shaped steel comprises the following chemical components in percentage by mass: 0.06%-0.18% of C, 0.15%-0.40% of Si, 1.20%-1.60% of Mn, less than or equal to 0.025% of P, less than or equal to 0.025% of S, 0.010%-0.020% of Ti, 0.010%-0.020% of Re and the balance of Fe and inevitable impurities, and the total mass fraction is 100%. The production method comprises the steps of converter smelting, LF refining, beam blank continuous casting, casting blank stacking and slow cooling, beam blank heating and rolling. The invention aims to provide the production method of the hot-rolled H-shaped steel for the ocean engineering structure, and the hot-rolled H-shaped steel for ocean engineering, which is better in performance, lower in cost and better in economic benefit, is prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of smelting, continuous casting and rolling, and in particular relates to a production method of hot-rolled H-shaped steel for marine engineering structures. Background Art

[0002] With the continuous increase in the development of global marine resources, marine engineering projects, such as offshore wind farms, offshore oil drilling platforms, submarine pipelines and marine aquaculture facilities, are developing rapidly. As an important part of marine engineering structures, H-shaped steel is widely used in various structural supports of marine engineering due to its superior bearing capacity and good cross-sectional performance. The successful development of hot-rolled H-shaped steel for marine engineering structures will provide more reliable and durable structural materials for marine engineering, help the efficient development of my country's marine resources, and promote the further improvement of marine engineering equipment manufacturing technology. At the same time, this high-performance hot-rolled H-shaped steel also has broad market prospects worldwide, which can enhance the competitiveness of my country's steel industry in the international market.

[0003] Publication No. CN 105886961 A mainly introduces a hot-rolled H-beam with excellent corrosion resistance in marine environment and its production process, focusing on improving its corrosion resistance and mechanical properties. This patent introduces the production of hot-rolled H-beam with optimized chemical composition and excellent mechanical properties for marine engineering structures through converter smelting, LF refining and other processes. This patent not only improves the low-temperature toughness of steel by adding rare earth elements and optimizing the process, but also significantly reduces the production cost, which is particularly suitable for large-scale industrial production.

[0004] Publication No. CN 111945064 A mainly introduces a low-temperature resistant 355MPa grade hot-rolled H-beam suitable for marine engineering and its preparation process, focusing on improving the strength and toughness of steel in low-temperature environments. This patent introduces the production of hot-rolled H-beam with excellent mechanical properties for marine engineering structures by optimizing chemical composition and process flow. This patent uses rare earth microalloying technology to not only significantly improve the low-temperature impact toughness of steel, but also reduce production costs, making it more suitable for large-scale industrial production.

[0005] Publication No. CN 103556055 A produces a hot-rolled H-shaped steel with a yield strength of 400 MPa for offshore natural gas production platform structures by adding alloy elements Nb and Ti to steel. This patent adds rare earth alloys to replace part of the Nb alloy to reduce alloy costs and refine grains. By adding rare earth elements, the method of this patent produces hot-rolled H-shaped steel for offshore engineering with better performance, lower cost and better economic benefits than Document 1. Summary of the invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide a production method of hot-rolled H-shaped steel for marine engineering structures, so as to prepare a hot-rolled H-shaped steel for marine engineering with better performance, lower cost and better economic benefits.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention discloses a production method of hot-rolled H-shaped steel for marine engineering structures. The mass percentage of chemical components of the hot-rolled H-shaped steel includes: C 0.06%-0.18%, Si 0.15%-0.40%, Mn 1.20%-1.60%, P≤0.025%, S≤0.025%, Ti 0.010%-0.020%, Re 0.010%-0.020%, and the rest is Fe and inevitable impurities, with the mass fraction totaling 100%. The production method comprises: converter smelting, LF refining, profiled blank continuous casting, billet stacking slow cooling, profiled blank heating, and rolling; wherein:

[0009] In combined blowing converter smelting, the final slag basicity is controlled at 3.0, the endpoint control target C≥0.03%, T≥1640℃, SiMn and MnFe are used for deoxidation and alloying, and Al is used for final deoxidation. Lime is added during the steelmaking process to prevent slag during steelmaking.

[0010] Refining white slag operation, dip the slag sample after lifting the electrode each time, add silicon calcium barium according to the slag color, add white ash according to the slag viscosity, and the final slag requires white slag. Blow Ar throughout the process, desulfurization, composition fine-tuning and temperature increase operations are performed according to the composition and temperature of the converter molten steel; titanium iron and rare earth are added in the later stage of refining, and after adding, ensure that Ti is 0.010~0.020%, Re is 0.010%~0.020%, and the soft blowing time is guaranteed to be more than 15min;

[0011] Protected pouring is adopted throughout the whole process, the superheat is ≤30℃, and the weak cooling system is adopted. Before entering the straightening machine, the target temperature of the billet web is ≥900℃, and the target temperature of the billet flange is ≥800℃. The constant pulling speed operation is adopted, and the pulling speed is controlled at 0.9m / min-1.0m / min. After the continuous casting billet is cut, it is promptly taken offline and stacked for slow cooling, and the slow cooling time is greater than 48 hours.

[0012] Furthermore, the cross-sectional dimensions of the continuous casting billet are H350mm×290mm×100mm.

[0013] Furthermore, the mass percentage of the chemical composition of the hot-rolled H-beam includes: C 0.09%, Si 0.22%, Mn 1.47%, P 0.014%, S 0.009%, Ti 0.016%, Re 0.013%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0014] Furthermore, the mass percentage of the chemical composition of the hot-rolled H-beam includes: C 0.10%, Si 0.25%, Mn 1.45%, P 0.015%, S 0.010%, Ti 0.015%, Re 0.014%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0015] Furthermore, the mass percentage of the chemical composition of the hot-rolled H-beam includes: C 0.09%, Si 0.28%, Mn 1.46%, P 0.015%, S 0.008%, Ti 0.014%, Re 0.015%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0016] Furthermore, the hot-rolled H-beam can exhibit better toughness while maintaining higher strength, especially in harsh marine environments and low temperature conditions, thereby reducing the risk of brittle fracture.

[0017] Compared with the prior art, the beneficial technical effects of the present invention are:

[0018] (1) Rare earth elements can refine the grains of steel, purify grain boundaries and reduce harmful inclusions, thereby improving the overall strength and toughness of steel. Especially in low temperature environments, the effect of rare earth elements is particularly significant, which can effectively prevent the brittle fracture of H-shaped steel under low temperature conditions and improve the safety and reliability of the structure.

[0019] (2) By using rare earth elements to replace some expensive traditional alloying elements, the production cost can be reduced while maintaining or even improving the performance of steel. While rare earth elements improve the performance of steel, their addition amount is usually small, so it can effectively reduce the dependence on scarce and expensive alloy resources and improve economic benefits. The properties of the H-beam after rolling meet the standard requirements, with good mechanical properties, especially good low-temperature impact toughness, carbon equivalent CEV ≤ 0.36, and good welding performance. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below

[0021] The invention discloses a method for hot-rolling H-shaped steel for marine engineering structure. The chemical components of the H-shaped steel include: C 0.06%-0.18%, Si 0.15%-0.40%, Mn 1.20%-1.60%, P≤0.025%, S≤0.025%, Ti0.010%-0.020%, Re 0.010%-0.020%, and the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

[0022] The smelting process of hot-rolled H-shaped steel for marine engineering structure of the present invention comprises the following steps: converter smelting, LF refining, continuous casting of profiled billets, slow cooling of stacked cast billets, heating of profiled billets and rolling.

[0023] Further: combined blowing converter smelting, final slag basicity is controlled at 3.0, endpoint control target C≥0.03%, T≥1640℃, SiMn and MnFe deoxidation alloying are used, final deoxidation uses Al deoxidation, lime is added during steelmaking, and slag is blocked during steelmaking.

[0024] Further: Refining white slag operation, dip the slag sample after each electrode is lifted, add silicon calcium barium according to the color of the slag, add white ash according to the viscosity of the slag, and the final slag requires white slag. Blow Ar operation is carried out throughout the process, desulfurization, component fine-tuning and temperature increase operation are carried out according to the composition and temperature of the converter molten steel. After desulfurization, S≤0.010%, the composition content is C 0.08%~0.10%, Si 0.20%~0.30%, Mn 1.40%~1.50%, P≤0.017%, S≤0.010%, and the temperature after heating is T≥1560℃. Titanium iron and rare earth are added in the later stage of refining. After adding, Ti 0.010~0.020%, Re 0.010%~0.020% are guaranteed, and the soft blowing time is guaranteed to be greater than 15min.

[0025] Further: The composition of the molten steel for continuous casting is C 0.09%, Si 0.22%, Mn 1.47%, P 0.014%, S0.009%, Ti 0.015%, Re 0.012%.

[0026] Further: protective pouring is adopted throughout the process, superheat is ≤30℃, weak cooling system is adopted, before entering the straightening machine, the target temperature of the billet web is ≥900℃, the target temperature of the billet flange is ≥800℃, constant pulling speed operation is adopted, the pulling speed is controlled at 0.9m / min-1.0m / min, and the continuous casting billet is promptly taken offline and stacked for slow cooling after cutting, and the slow cooling time is greater than 48 hours.

[0027] Further: the cross-sectional dimensions of the continuous casting billet are H350mm×290mm×100mm.

[0028] Further: inspect the surface quality of hot-rolled H-beam special-shaped continuous casting billets for marine engineering structures, conduct low-power hot acid inspection on the internal quality and track the quality of H-beam.

[0029] Further: No obvious surface and internal quality defects of the ingot were found during the inspection. The quality of the ingot is good, and the surface crack rate of the ingot is less than 2%.

[0030] Further: the special-shaped continuous casting billet is heated in a digitally controlled heating furnace, the heating temperature of the billet is 1200-1280°C, the insulation time is 2.5-4 hours, and the billet is descaled by high-pressure water after being taken out of the furnace.

[0031] Further: the rough rolling temperature is 1100-1200℃, water cooling is used for controlled cooling, the rolling passes are 3-5 times, and then the rough rolled profile is sent to the finishing mill for rolling. The finishing rolling temperature is 900-980℃, and the finishing rolling adopts warm rolling and water cooling controlled rolling, and the rolling passes are 5-7 times. The final rolling temperature is 860-900℃, and the total reduction of the two-stage rolling is ≥75%. After rolling is completed, air cooling is carried out and concentrated cooling is carried out in the cooling bed. After the temperature drops below 100℃, it is straightened in the straightening machine, and finally cut to size and bundled.

[0032] Further: the finished product size is H300×300×10×15×12000mm.

[0033] The surface quality of the finished product of ultra-high strength hot-rolled H-beam for marine engineering structures was inspected, and the mechanical properties were tested at the same time. No obvious surface quality defects of the finished product were found during the inspection, the surface quality was good, and the various properties of the H-beam after rolling met the standard requirements. Table 1 is the chemical composition of each steel grade, and Tables 2, 3, and 4 further illustrate the present invention in combination with the embodiments and comparative examples.

[0034] Table 1 Chemical composition of each embodiment and comparative example (mass percentage / %)

[0035] Examples C Si Mn P S Nb Ti Re Example 1 0.09 0.22 1.47 0.014 0.009 —— 0.016 0.013 Example 2 0.10 0.25 1.45 0.015 0.010 —— 0.015 0.014 Example 3 0.09 0.28 1.46 0.015 0.008 —— 0.014 0.015 Example 4 0.10 0.23 1.43 0.013 0.007 —— 0.018 0.016 Comparative Example 1 0.12 0.20 1.40 0.015 0.009 0.034 0.016 —— Comparative Example 2 0.13 0.18 1.36 0.011 0.006 0.032 0.018 —— Comparative Example 3 0.14 0.19 1.35 0.013 0.005 0.030 0.015 —— Comparative Example 4 0.13 0.20 1.37 0.014 0.008 0.033 0.016 ——

[0036] Table 2 Non-metallic inclusions and austenite grain size of each embodiment and comparative example

[0037]

[0038] Table 3 Carbon equivalent of each embodiment and comparative example

[0039]

[0040]

[0041] Table 4 Mechanical properties of H-beam after rolling in various embodiments and comparative examples

[0042]

[0043] From Table 1-4 we can see that:

[0044] (1) The addition of rare earth elements not only optimizes the microstructure of the steel, but also promotes grain refinement, thereby significantly improving the strength and toughness of the steel. Compared with the comparative example, the material in the embodiment can maintain higher strength while showing better toughness, especially in harsh marine environments and low temperature conditions, reducing the risk of brittle fracture.

[0045] (2) By replacing part of the alloying elements with rare earth elements, the steel in the embodiment achieves a reduction in carbon equivalent. Low carbon equivalent means less hardening tendency and lower crack sensitivity of the material during welding, thereby significantly improving welding performance. Compared with the comparative example, the steel in the embodiment has a lower carbon equivalent, and the welding process is more stable and reliable.

[0046] (3) The amount of rare earth elements used is usually small, but they can effectively replace some expensive traditional alloy elements. The embodiment reduces the use of these scarce alloys, not only reducing material costs, but also improving the overall economic benefits without affecting the performance of steel.

[0047] 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 method for producing hot-rolled H-shaped steel for marine engineering structures, characterized in that: The mass percentage of the chemical composition of the hot-rolled H-beam includes: C 0.06%-0.18%, Si 0.15%-0.40%, Mn 1.20%-1.60%, P≤0.025%, S≤0.025%, Ti 0.010%-0.020%, Re 0.010%-0.020%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%. The production method includes: converter smelting, LF refining, profiled billet continuous casting, billet stacking slow cooling, profiled billet heating, and rolling; wherein: In combined blowing converter smelting, the final slag basicity is controlled at 3.0, the endpoint control target C≥0.03%, T≥1640℃, SiMn and MnFe are used for deoxidation and alloying, and Al is used for final deoxidation. Lime is added during the steelmaking process to prevent slag during steelmaking. Refining white slag operation, dip the slag sample after lifting the electrode each time, add silicon calcium barium according to the slag color, add white ash according to the slag viscosity, and the final slag requires white slag. Blow Ar throughout the process, desulfurization, composition fine-tuning and temperature increase operations are performed according to the composition and temperature of the converter molten steel; titanium iron and rare earth are added in the later stage of refining, and after adding, ensure that Ti is 0.010~0.020%, Re is 0.010%~0.020%, and the soft blowing time is guaranteed to be more than 15min; Protected pouring is adopted throughout the whole process, the superheat is ≤30℃, and the weak cooling system is adopted. Before entering the straightening machine, the target temperature of the billet web is ≥900℃, and the target temperature of the billet flange is ≥800℃. The constant pulling speed operation is adopted, and the pulling speed is controlled at 0.9m / min-1.0m / min. After the continuous casting billet is cut, it is promptly taken offline and stacked for slow cooling, and the slow cooling time is greater than 48 hours.

2. The method for producing hot-rolled H-shaped steel for marine engineering structures according to claim 1, characterized in that: The cross-sectional dimensions of the continuous casting billet are H350mm×290mm×100mm.

3. The method for producing hot-rolled H-shaped steel for marine engineering structures according to claim 1, characterized in that: The mass percentage of the chemical composition of the hot-rolled H-beam includes: C 0.09%, Si 0.22%, Mn 1.47%, P 0.014%, S 0.009%, Ti 0.016%, Re 0.013%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

4. The method for producing hot-rolled H-shaped steel for marine engineering structures according to claim 1, characterized in that: The mass percentage of the chemical composition of the hot-rolled H-beam includes: C 0.10%, Si 0.25%, Mn 1.45%, P 0.015%, S 0.010%, Ti 0.015%, Re 0.014%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

5. The method for producing hot-rolled H-shaped steel for marine engineering structures according to claim 1, characterized in that: The mass percentage of the chemical composition of the hot-rolled H-beam includes: C 0.09%, Si 0.28%, Mn 1.46%, P 0.015%, S 0.008%, Ti 0.014%, Re 0.015%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

6. The method for producing hot-rolled H-shaped steel for marine engineering structures according to claim 1, characterized in that: The hot-rolled H-shaped steel can exhibit better toughness while maintaining higher strength, especially in harsh marine environments and low temperature conditions, reducing the risk of brittle fracture.

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