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

Abstract

The invention discloses a production method of low-cost hot-rolled H-shaped steel for an ocean engineering structure. The production method comprises the steps of converter smelting, LF refining, VD vacuum degassing, beam blank continuous casting, casting blank heating and rolling. The low-cost hot-rolled H-shaped steel for the ocean engineering structure comprises the following chemical components in percentage by mass: 0.10%-0.15% of C, 0.20%-0.30% of Si, 1.30%-1.50% of Mn, less than or equal to 0.020% of P, less than or equal to 0.020% of S, 0.02%-0.03% of Re and the balance of Fe and inevitable impurities, and the total mass fraction is 100%. The rare earth element Re is added to replace traditional alloys such as Nb, V and Ti, so that the production cost is effectively reduced, and meanwhile, good strength and low-temperature toughness are achieved.

Description

Technical Field

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

[0002] The demand for marine engineering steel is increasing year by year, especially in the context of increasing global development of marine resources, the market demand for high-performance, low-cost materials is growing. Developing a low-cost H-shaped steel for marine engineering, by adding rare earth elements to replace traditional alloys such as Nb and V, can not only effectively reduce production costs, but also ensure that the performance of steel meets the strict requirements of marine engineering. Rare earth elements have a unique role in steel, which can improve the plasticity, toughness and corrosion resistance of steel, while refining grains and improving the comprehensive mechanical properties of materials. Compared with expensive alloy elements such as Nb and V, rare earth resources are abundant and relatively cheap, so this substitution strategy can significantly reduce production costs and improve market competitiveness. The addition of rare earth elements can not only help steel mills reduce production costs, but also enhance the technical advantages of products, increase added value, help occupy more market share, and promote my country's marine engineering steel technology to the international market. This new type of H-shaped steel has broad market prospects and application value, and will be widely used in offshore platforms, submarine pipelines, shipbuilding and other fields in the future.

[0003] Publication No. CN 118186293 A introduces a production method for hot-rolled H-beam AH40 for marine engineering structures, whose chemical composition contains elements such as C, Si, Mn, P, S, Nb, V and the like in specific proportions. Through converter smelting, LF refining, continuous casting of special-shaped billets, slow cooling of billet stacking and the like, the final slag basicity, endpoint composition and temperature, refining operation, casting conditions, continuous casting parameters and the like are controlled, and the AH40 hot-rolled H-beam billet produced is of good quality, and the performance after rolling meets the standard requirements and has good mechanical properties, especially low-temperature impact toughness. This patent discloses a low-cost hot-rolled H-shaped steel for marine engineering structures and a production method thereof. The chemical composition of the H-shaped steel contains specific proportions of C, Si, Mn, P, S, Re and other elements. Through converter smelting, LF refining, VD vacuum degassing, special-shaped billet continuous casting, billet heating, rolling and other processes, the parameters of each link are controlled, such as converter final slag basicity, refining conditions, VD vacuum degree, continuous casting parameters, heating temperature and time, rolling temperature and pass number, etc. The produced H-shaped steel has good strength and low-temperature toughness, and is lower in cost than the method of micro-alloying with alloy elements such as Nb and V.

[0004] Publication No. CN 118186293 A discloses a production method of FH36 hot-rolled H-beam for marine engineering structures, which has a specific chemical composition. Through converter smelting, LF refining, continuous casting of special-shaped billets, slow cooling of billet stacking, etc., the parameters of each link are controlled, including final slag basicity, end point composition and temperature, refining operation, pouring conditions, continuous casting parameters, etc., so that the produced FH36 hot-rolled H-beam billet has good quality, low surface crack rate, and performance after rolling meets the standard and has good mechanical properties, especially low-temperature impact toughness. This patent adds a VD vacuum degassing link in the production process, which is conducive to further improving the purity of molten steel, and by using the rare earth element Re, the production cost is effectively reduced while ensuring the performance of the steel.

[0005] Publication No. CN 118127285 A introduces and discloses a method for producing hot-rolled H-shaped steel containing Ni for marine engineering structures, whose chemical composition contains C, Si, Mn, P, S, Nb, V, Ni and other elements in specific proportions, and obtains the special-shaped steel through processes such as combined blowing converter smelting, LF refining, special-shaped steel continuous casting, and slow cooling of cast steel stacking, and then undergoes processes such as special-shaped steel heating, rough rolling, fine rolling, and cooling. The produced H-shaped steel has excellent yield strength, tensile strength, elongation, and low-temperature impact energy, and can be used in harsh deep-sea environments, and has good surface quality. This patent uses rare earth element Re, effectively reduces production costs and improves the market competitiveness of products while ensuring the performance of steel, and the provisions of parameters in each link in process control are more detailed and comprehensive, which is conducive to the stable production of high-quality and low-cost hot-rolled H-shaped steel for marine engineering structures. Summary of the invention

[0006] The purpose of the present invention is to provide a method for producing hot-rolled H-shaped steel for marine engineering structures at a low cost, thereby reducing the cost and optimizing the mechanical properties.

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

[0008] The present invention discloses a method for producing low-cost hot-rolled H-shaped steel for marine engineering structures, comprising converter smelting, LF refining, VD vacuum degassing, profiled billet continuous casting, billet heating, and rolling; wherein:

[0009] The converter uses low-sulfur molten iron and adopts top-bottom combined blowing technology to control the final slag basicity within the range of 2.0-3.8. Slag blocking operation is performed during steel tapping, and aluminum-manganese-iron is used for deoxidation and alloying during steel tapping.

[0010] During the refining process, white slag operation is implemented to adjust the slag with calcium carbide, silicon calcium barium and aluminum particles. It must be ensured that the white slag state is achieved before leaving the station. When the refining furnace enters the station, the initial sample is taken first, and then the oxygen content is measured, and the oxygen content is required to be no more than 20ppm. Bottom argon blowing operation must be carried out continuously throughout the refining process, and the soft blowing time must not be less than 15 minutes, and the refining cycle must not be less than 25 minutes;

[0011] When the molten steel is degassed by VD vacuum, the vacuum degree should be less than 67Pa. This is to prevent the molten steel from churning and absorbing nitrogen when in contact with air, and also to prevent the molten steel from being oxidized again. In addition, the weak stirring time before the molten steel leaves the station should be no less than 28 minutes, which is conducive to the floating of alumina inclusions.

[0012] The continuous casting process uses a full-protection pouring process, uses a long water nozzle for the large ladle, and installs a sealing ring; for the tundish, a plugger is used to pour molten steel, and the billet pulling speed must be reasonably controlled to prevent the water nozzle from being blocked, and the superheat is controlled within the range of 15-30℃; the billet pulling speed is set at 0.7-1.0m / min, and the smelted molten steel is poured into rectangular billets;

[0013] When heating the profiled blank, the heating furnace must be in a reducing atmosphere. The temperature of the preheating section must not be higher than 890°C, the temperature of the first heating section must not exceed 1050°C, the temperature of the second heating section must be controlled at 1100-1200°C, and the temperature of the soaking section must be controlled at 1200-1260°C. The entire heating process lasts for 2.5-3.2 hours.

[0014] Before the ingot enters BD1, it needs to be descaled with high-pressure water to remove the iron oxide scale on the surface of the ingot, so as to ensure the smoothness of the finished product surface;

[0015] The two-stage rolling process includes BD1 blanking and CCS finishing rolling. The rolling temperature of BD1 blanking mill is set in the range of 1130-1180℃. Five rolling passes are required, and the reduction rate is greater than or equal to 50%. The rough-rolled profiled blank is transferred to the finishing mill for rolling operation. The temperature during finishing rolling is in the range of 910-970℃. The finishing rolling process adopts the method of warm rolling and water-cooled controlled rolling, and the rolling passes are 5 times. The final rolling temperature is controlled at 850-880℃, and the total reduction of the two-stage rolling is not less than 75%. After rolling, air cooling is carried out, and then the steel enters the cooling bed for centralized cooling. The distance between each steel and the two steels in front and behind is 0.8±0.2m. When the temperature drops below 100℃, the straightening operation is carried out at the straightening machine, and finally the cutting to size and bundling are carried out.

[0016] The mass percentage of the chemical composition of the low-cost hot-rolled H-shaped steel for marine engineering structures includes: C 0.10%-0.15%, Si 0.20%-0.30%, Mn 1.30%-1.50%, P≤0.020%, S≤0.020%, Re 0.02-0.03%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0017] Furthermore, the cross-sectional dimensions of the continuous casting billet are H555mm×440mm×105mm.

[0018] Furthermore, the finished product size is H300×300×10×15×12000mm.

[0019] Furthermore, the mass percentage of the chemical composition of the low-cost hot-rolled H-beam for marine engineering structures includes: C 0.14%, Si 0.21%, Mn 1.39%, P 0.016%, S 0.004%, Re 0.025%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0020] Furthermore, the mass percentage of the chemical composition of the low-cost hot-rolled H-beam for marine engineering structures includes: C 0.10%, Si 0.26%, Mn 1.40%, P 0.014%, S 0.007%, Re 0.024%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0021] Furthermore, the mass percentage of the chemical composition of the low-cost hot-rolled H-beam for marine engineering structures includes: C 0.13%, Si 0.24%, Mn 1.35%, P 0.014%, S 0.005%, Re 0.022%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0022] Furthermore, the mass percentage of the chemical composition of the low-cost hot-rolled H-beam for marine engineering structures includes: C 0.11%, Si 0.23%, Mn 1.41%, P 0.016%, S 0.004%, Re 0.028%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are:

[0024] (1) By adding the rare earth element Re to replace traditional alloys such as Nb, V, and Ti, the production cost is effectively reduced. Rare earth resources are abundant and relatively cheap. For example, compared with comparative examples 2, 3, 4, and 5, the alloy cost of Example 1 is significantly reduced, which is reduced by 84.04 yuan / ton, 127.10 yuan / ton, 57.46 yuan / ton, and 159.29 yuan / ton, respectively. (2) The low-cost hot-rolled H-beam for marine engineering structures of the present invention has good strength and low-temperature toughness. The properties of the steel meet the following requirements: yield strength ≥ 370MPa, tensile strength ≥ 520MPa, elongation ≥ 28%; -20℃ transverse impact absorption energy KV2 ≥ 100J, -20℃ longitudinal impact energy ≥ 250J (as shown in Examples 1-4, all mechanical performance indicators meet or exceed the standard requirements. DETAILED DESCRIPTION

[0025] Embodiment 1:

[0026] A method for producing low-cost hot-rolled H-shaped steel for marine engineering structures, the production process is carried out in the following steps:

[0027] The converter uses low-sulfur molten iron and top and bottom double blowing technology. The final slag basicity is 2.8. Slag blocking operation is performed during steel tapping, and aluminum-manganese-iron is used for deoxidation and alloying treatment during the steel tapping process.

[0028] During the refining process, white slag operation is implemented. When the refining furnace enters the station, the initial sample is taken first, and then the oxygen content is measured, which is 15ppm. Bottom argon blowing operation is carried out continuously throughout the refining process, with a soft blowing time of 18 minutes and a refining cycle of 28 minutes.

[0029] When the molten steel is degassed in VD vacuum, the vacuum degree is 55 Pa. The weak stirring time before the molten steel leaves the station is 32 minutes.

[0030] The continuous casting process uses a full-protection pouring process, with an overheat of 25°C and a casting speed of 0.8m / min.

[0031] The special-shaped blanks are heated, wherein the temperature of the preheating section is 880°C, the temperature of the first heating section is 1030°C, the temperature of the second heating section is 1120°C, the temperature of the soaking section is 1220°C, and the entire heating process lasts for 2.6 hours.

[0032] High-pressure water descaling is used to remove the iron oxide scale on the surface of the ingot.

[0033] The two-stage rolling process includes BD1 slab opening and CCS finishing rolling. The BD1 slab opening mill has a rolling temperature of 1150℃, 5 passes, and a reduction rate of 50%. The finishing rolling temperature is 950℃, and 5 passes are rolled. The final rolling temperature is 880℃. After rolling, the steel is air-cooled and then enters the cooling bed for centralized cooling. The distance between each steel bar and the two steel bars in front and behind is 0.8m. When the temperature drops below 100℃, it is straightened, cut to size, and bundled.

[0034] Example 2-4: Except for some specific process parameters that are different from those in Example 1, the rest of Example 2-4 is exactly the same as Example 1. See Table 1 for specific process parameters.

[0035] Table 1 Process parameters of each embodiment

[0036]

[0037]

[0038] Comparative Example 1:

[0039] Comparative Example 1 is completely the same as Example 1 except that the content of the rare earth element Re is different from that of Example 1. The content of the rare earth element Re in this comparative example is 0.050%.

[0040] Comparative Example 2:

[0041] Comparative Example 2 is completely the same as Example 1 except that Nb and Ti elements are used to replace the rare earth element Re for microalloying, which is different from Example 1. The Nb content of this comparative example is 0.020% and the Ti content is 0.035%. Adding one Re increases the cost by 2.43 yuan; adding one Ti increases the cost by 5.65 yuan; adding one Nb increases the cost by 35.17 yuan. Example 1 adds 2.5 Re, and Comparative Example 1 adds 2.0 Nb elements and 3.5 Ti elements. Compared with Comparative Example 2, the cost of a ton of steel in Example 1 is reduced by 84.04 yuan.

[0042] Comparative Example 3:

[0043] Comparative Example 3 is completely the same as Example 1 except that Nb and V elements are used to replace the rare earth element Re for microalloying, which is different from Example 1. The Nb content of this comparative example is 0.020%, and the V content is 0.035%. Adding one Re increases the cost by 2.43 yuan; adding one V increases the cost by 23.29 yuan; adding one Nb increases the cost by 35.17 yuan. Example 1 adds 2.5 Re, and Comparative Example 1 adds 1.8 Nb elements and 3.0 V elements. Compared with Comparative Example 3, the cost of a ton of steel in Example 1 is reduced by 127.10 yuan.

[0044] Comparative Example 4:

[0045] Comparative Example 4 is completely the same as Example 1 except that Ti and V elements are used to replace the rare earth element Re for microalloying, which is different from Example 1. The Ti content of this comparative example is 0.030% and the V content is 0.020%. Adding one Re increases the cost by 2.43 yuan; adding one Ti increases the cost by 5.65 yuan; adding one V increases the cost by 23.29 yuan. Example 1 adds 2.5 Re, and Comparative Example 1 adds 3.0 Ti elements and 2.0 V elements. Compared with Comparative Example 4, the cost of one ton of steel in Example 1 is reduced by 57.46 yuan.

[0046] Comparative Example 5:

[0047] Comparative Example 5 is completely the same as Example 1 except that the rare earth element Re is replaced by Ti, V, and Nb elements for microalloying, which is different from Example 1. The Ti content of this comparative example is 0.030%, the V content is 0.040%, and the Nb content is 0.018%. Adding one Re increases the cost by 2.43 yuan; adding one Ti increases the cost by 5.65 yuan; adding one V increases the cost by 23.29 yuan; adding one Nb increases the cost by 35.17 yuan. Example 1 adds 2.5 Re, and Comparative Example 1 adds 3.0 Ti elements, 4.0 V elements, and 1.8 Nb elements. Compared with Comparative Example 5, the cost of one ton of steel in Example 1 is reduced by 159.29 yuan.

[0048] Comparative Example 6:

[0049] Comparative Example 6 is completely the same as Example 1 except that the VD vacuum degassing process is not performed, which is different from Example 1.

[0050] Comparative Example 7:

[0051] Comparative Example 7 is completely the same as Example 1 except that the final rolling temperature is not controlled, which is different from Example 1. The final rolling temperature of this comparative example is 950°C.

[0052] The surface quality of the finished hot-rolled H-beam for low-cost marine engineering structures was inspected, and the mechanical properties were tested. No obvious surface quality defects of the finished products 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 2 is the chemical composition of each embodiment, and Table 3 further illustrates the present invention in combination with the embodiments and comparative examples.

[0053] Table 2 Chemical composition of each example (mass percentage / %)

[0054] Example C Si Mn P S Nb V Ti Re Example 1 0.14 0.21 1.39 0.016 0.004 —— —— —— 0.025 Example 2 0.10 0.26 1.40 0.014 0.007 —— —— —— 0.024 Example 3 0.13 0.24 1.35 0.014 0.005 —— —— —— 0.022 Example 4 0.11 0.23 1.41 0.016 0.004 —— —— —— 0.028 Comparative Example 1 0.12 0.25 1.37 0.015 0.015 —— —— —— 0.050 Comparative Example 2 0.13 0.23 1.38 0.015 0.014 0.020 —— 0.035 —— Comparative Example 3 0.12 0.24 1.34 0.014 0.015 0.018 0.030 —— —— Comparative Example 4 0.11 0.25 1.42 0.013 0.016 —— 0.020 0.030 —— Comparative Example 5 0.12 0.22 1.37 0.015 0.012 0.018 0.040 0.030 —— Comparative Example 6 0.12 0.22 1.37 0.015 0.016 —— —— —— 0.026 Comparative Example 7 0.13 0.25 1.38 0.013 0.015 —— —— —— 0.027

[0055] Table 2 Mechanical properties of H-beam after rolling in various embodiments

[0056]

[0057] As can be seen from Table 2, (1) the content of rare earth element Re in Comparative Example 1 is 0.050%, which is higher than the range of 0.02-0.03% in the embodiment. The embodiment avoids the cost increase caused by excessive addition of rare earth elements by reasonably controlling the content of rare earth elements while ensuring the performance of steel. Although the strength index of Comparative Example 1 is similar to that of the embodiment, the impact energy is significantly lower than that of the embodiment, especially the lateral impact absorption energy is only about 57% of that of Example 1, indicating that the higher the content of rare earth element Re is, the better. The embodiment has better low-temperature toughness while ensuring strength. (2) Comparative Examples 2-5 use Nb, Ti, V and other elements to replace the rare earth element Re for microalloying, and these alloying elements are expensive. Adding one Re increases the cost by 2.43 yuan, while adding one Ti increases the cost by 5.65 yuan, adding one Nb increases the cost by 35.17 yuan, and adding one V increases the cost by 23.29 yuan. Example 1 adds 2.5 Re, and compared with Comparative Example 2 (adding 2.0 Nb elements and 3.5 Ti elements), the cost per ton of steel is reduced by 84.04 yuan; compared with Comparative Example 3 (adding 1.8 Nb elements and 3.0 V elements), the cost per ton of steel is reduced by 127.10 yuan; compared with Comparative Example 4 (adding 3.0 Ti elements and 2.0 V elements), the cost per ton of steel is reduced by 57.46 yuan; compared with Comparative Example 5 (adding 3.0 Ti elements, 4.0 V elements, and 1.8 Nb elements), the cost per ton of steel is reduced by 159.29 yuan. However, the embodiment performs better in terms of yield strength, tensile strength, elongation, and impact energy, indicating that the embodiment obtains better comprehensive mechanical properties while reducing costs by adding the rare earth element Re. (3) Comparative Example 6 does not perform the VD vacuum degassing process, while the embodiment performs this process. VD vacuum degassing can prevent molten steel from churning, nitrogen absorption and re-oxidation, and ensures that the molten steel is weakly stirred before leaving the station, which is conducive to the floating of alumina inclusions, thereby improving the purity of the steel. The embodiment ensures the quality of the steel through a complete process flow, including VD vacuum degassing, so that the performance of the finished product is better than that of Example 6, while Example 6 does not perform this process, which affects the performance of the steel. (4) Example 7 does not perform final rolling temperature control, and the final rolling temperature is 950°C, while the final rolling temperature of the embodiment is controlled at 850-880°C. The embodiment is conducive to obtaining good performance by precisely controlling the final rolling temperature. From the mechanical property data, the embodiment is superior to Example 7 in terms of yield strength, tensile strength, elongation and impact energy, indicating that reasonable final rolling temperature control plays an important role in ensuring steel performance.

[0058] It can be seen from the above embodiments and comparative examples that: (1) By adding an appropriate amount of rare earth element Re to replace traditional expensive alloys such as Nb and V, the cost is significantly reduced while ensuring the performance of the steel. (2) The low-cost hot-rolled H-beam for marine engineering structures of the present invention has good strength and low-temperature toughness and other performance indicators that are better than the comparative examples. (3) The present invention has unique advantages in component selection, production process and product performance, and provides a new, more economical and high-performance solution for the production of hot-rolled H-beam for marine engineering structures.

[0059] 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 low-cost hot-rolled H-shaped steel for marine engineering structures, characterized in that: Including converter smelting, LF refining, VD vacuum degassing, beam billet continuous casting, billet heating, rolling; among which: The converter uses low-sulfur molten iron and adopts top-bottom combined blowing technology to control the final slag basicity within the range of 2.0-3.

8. Slag blocking operation is performed during steel tapping, and aluminum-manganese-iron is used for deoxidation and alloying during steel tapping. During the refining process, white slag operation is implemented, and calcium carbide, silicon calcium barium and aluminum particles are used to adjust the slag. Before leaving the station, it must be ensured that the slag reaches the white slag state. When the refining furnace enters the station, the initial sample is taken first, and then the oxygen content is measured, and the oxygen content is required to be no more than 20ppm. During the entire refining process, the bottom argon blowing operation must be carried out continuously, and the soft blowing time must not be less than 15 minutes, and the refining cycle must not be less than 25 minutes. When the molten steel is degassed by VD vacuum, the vacuum degree should be less than 67Pa. This is to prevent the molten steel from churning and absorbing nitrogen when in contact with air, and also to prevent the molten steel from being oxidized again. In addition, the weak stirring time before the molten steel leaves the station should be no less than 28 minutes, which is conducive to the floating of alumina inclusions. The continuous casting process uses a full-protection pouring process, uses a long water nozzle for the large ladle, and installs a sealing ring; for the tundish, a plugger is used to pour molten steel, and the billet pulling speed must be reasonably controlled to prevent the water nozzle from being blocked, and the superheat is controlled within the range of 15-30℃; the billet pulling speed is set at 0.7-1.0m / min, and the smelted molten steel is poured into rectangular billets; When heating the profiled blank, the heating furnace must be in a reducing atmosphere. The temperature of the preheating section must not be higher than 890°C, the temperature of the first heating section must not exceed 1050°C, the temperature of the second heating section must be controlled at 1100-1200°C, and the temperature of the soaking section must be controlled at 1200-1260°C. The entire heating process lasts for 2.5-3.2 hours. Before the ingot enters BD1, it needs to be descaled with high-pressure water to remove the iron oxide scale on the surface of the ingot, so as to ensure the smoothness of the finished product surface; The two-stage rolling process includes BD1 blanking and CCS finishing rolling. The rolling temperature of BD1 blanking mill is set in the range of 1130-1180℃. Five rolling passes are required, and the reduction rate is greater than or equal to 50%. The rough-rolled profiled blank is transferred to the finishing mill for rolling operation. The temperature during finishing rolling is in the range of 910-970℃. The finishing rolling process adopts the method of warm rolling and water-cooled controlled rolling, and the rolling passes are 5 times. The final rolling temperature is controlled at 850-880℃, and the total reduction of the two-stage rolling is not less than 75%. After rolling, air cooling is carried out, and then the steel enters the cooling bed for centralized cooling. The distance between each steel and the two steels in front and behind is 0.8±0.2m. When the temperature drops below 100℃, the straightening operation is carried out at the straightening machine, and finally the cutting to size and bundling are carried out. The mass percentage of the chemical composition of the low-cost hot-rolled H-shaped steel for marine engineering structures includes: C 0.10%-0.15%, Si 0.20%-0.30%, Mn 1.30%-1.50%, P≤0.020%, S≤0.020%, Re 0.02-0.03%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

2. The method for producing low-cost hot-rolled H-beam for marine engineering structures according to claim 1, characterized in that: The cross-sectional dimensions of the continuous casting billet are H555mm×440mm×105mm.

3. The method for producing low-cost hot-rolled H-beam for marine engineering structures according to claim 1, characterized in that: The finished product size is H300×300×10×15×12000mm.

4. The method for producing low-cost hot-rolled H-beam for marine engineering structures according to claim 1, characterized in that: The mass percentage of the chemical composition of the low-cost hot-rolled H-beam for marine engineering structures includes: C 0.14%, Si 0.21%, Mn 1.39%, P 0.016%, S 0.004%, Re 0.025%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

5. The method for producing low-cost hot-rolled H-beam for marine engineering structures according to claim 1, characterized in that: The mass percentage of the chemical composition of the low-cost hot-rolled H-beam for marine engineering structures includes: C 0.10%, Si 0.26%, Mn 1.40%, P 0.014%, S 0.007%, Re 0.024%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

6. The method for producing low-cost hot-rolled H-beam for marine engineering structures according to claim 1, characterized in that: The mass percentage of the chemical composition of the low-cost hot-rolled H-beam for marine engineering structures includes: C 0.13%, Si 0.24%, Mn 1.35%, P 0.014%, S 0.005%, Re 0.022%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

7. The method for producing low-cost hot-rolled H-beam for marine engineering structures according to claim 1, characterized in that: The mass percentage of the chemical composition of the low-cost hot-rolled H-beam for marine engineering structures includes: C 0.11%, Si 0.23%, Mn 1.41%, P 0.016%, S 0.004%, Re 0.028%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

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