Production method of high-strength steel pile for building structure

Abstract

The invention discloses a production method of a high-strength steel pile for a building structure, and belongs to the technical field of smelting continuous casting and rolling. The steel comprises the following chemical components in percentage by mass: 0.15%-0.18% of C, 0.35%-0.45% of Si, 1.30%-1.50% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.05%-0.08% of V, 0.010%-0.020% of Re and the balance of Fe and inevitable impurities, and the total mass fraction is 100%. The invention further discloses a production method of the high-strength steel pile for the building structure. The high-strength H-shaped steel pile for the building structure is successfully developed through control over the smelting and rolling processes such as converter smelting, LF refining, special-shaped blank continuous casting, casting blank stacking and slow cooling, special-shaped blank heating, rough rolling, finish rolling, control over the finish rolling temperature and the rolling reduction of each pass and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of smelting, continuous casting and rolling, and particularly relates to a production method of a high-strength steel pile for building structure. BACKGROUND

[0002] With the continuous expansion and increasing complexity of modern construction engineering, the requirements for the bearing capacity and stability of building structure on the foundation are also increasing. Steel piles, as an important foundation reinforcement and bearing structure material, are widely used in bridges, wharfs, high-rise buildings and deep foundation engineering due to their excellent bearing performance, convenient construction and adaptability to complex geological conditions. Traditional steel piles are mostly made of ordinary low-carbon or low-alloy steel, which can meet some building requirements, but the limitations of their strength, corrosion resistance and welding performance are particularly prominent in some extreme working conditions. Especially in high-stress environments or corrosive media (such as marine environments), traditional steel piles often have problems such as easy breakage and short service life, which cannot meet the requirements of high strength and durability.

[0003] In recent years, with the development of high-strength low-alloy steel technology, high-strength steel piles have gradually become a research and development hotspot for building structure steel. Through the optimization of chemical composition design (such as the addition of trace alloying elements) and the strict control of manufacturing processes (such as refining, rolling and heat treatment processes), this type of steel realizes high yield strength, good toughness and excellent welding performance. The development of high-strength steel piles for building structure not only can effectively improve the bearing capacity of the structure, reduce the amount of piles and engineering cost, but also can improve the construction efficiency and reduce carbon emissions, which conforms to the trend of green building and sustainable development. Therefore, the development of new materials and new processes for high-strength steel piles for building structure has become one of the important research directions in the current steel industry. SUMMARY

[0004] The purpose of the present application is to provide a production method of a high-strength steel pile for building structure, and successfully develop a high-strength H-shaped steel pile for building structure.

[0005] To solve the above technical problems, the present application adopts the following technical solutions:

[0006] The production process of the high-strength steel pile for building structure is: converter smelting, LF refining, shaped billet continuous casting, billet stacking and slow cooling, shaped billet heating, rough rolling, finish rolling, controlling the final rolling temperature and pass reduction; specifically:

[0007] In the converter smelting process, low-sulfur molten iron is selected, top and bottom combined blowing technology is adopted, the final slag basicity is controlled at 2.0-3.8, and slag is blocked when tapping. Aluminum manganese iron is used for deoxidization and alloying to ensure the purity and quality of the molten steel;

[0008] The refining white slag operation adopts calcium carbide, silicon calcium barium and aluminum particle to adjust the slag, and the molten steel is refined to white slag before outlet. After sampling, the oxygen content of the molten steel is controlled to be less than or equal to 20 ppm. The whole process is under argon blowing, the soft blowing time is not less than 15 minutes, the refining period is at least 25 minutes, and the refining quality is stable;

[0009] The continuous casting adopts full protection pouring process, a long water nozzle and a sealing ring are arranged in the ladle, and a stopper is used in the tundish to accurately control the flow. The casting speed is set to 0.7-1.0 m / min, and the superheat is controlled to be 15-30℃, so as to prevent the water nozzle from being blocked, ensure smooth pouring and uniform billet quality, and provide high-quality shaped billets for subsequent rolling;

[0010] The shaped continuous casting billet enters the heating furnace under digital control, and the heating process is started. In this process, the temperature of the billet is stabilized in the range of 1180 to 1250℃, so that the internal organization of the billet is homogenized. The holding time is controlled to be 200 to 230 minutes, so that the billet is fully heated. At the moment when the billet completes heating and leaves the furnace, a high-pressure water device is used for descaling operation to completely remove the iron oxide scale attached to the surface of the billet, so that the billet enters the next link in a clean state;

[0011] The rough rolling temperature is controlled to be 1100-1200℃, and the shaped billet after rough rolling is sent to the finishing rolling mill station for continuous rolling;

[0012] In the finishing rolling stage, the temperature needs to be controlled in the range of 920-1000℃, and the combination of temperature waiting rolling and water cooling control is used, and the shaped billet is rolled for 5-7 passes, and the final rolling temperature is stabilized at 850-900℃, and the total reduction of the two rolling stages is not less than 70%. After rolling, the shaped billet is air-cooled first, then concentrated cooling is carried out in the cooling bed, and then the shaped billet is moved to the straightening machine for straightening, and finally the shaped billet is cut to size and baled;

[0013] The chemical composition of the high-strength steel pile for building structure includes: C 0.15% to 0.18%, Si 0.35% to 0.45%, Mn 1.30% to 1.50%, P≤0.015%, S≤0.010%, V 0.05% to 0.08%, Re 0.010% to 0.020%, the rest is Fe and inevitable impurities, and the total mass fraction is 100%.

[0014] Further, the cross-sectional size of the continuous casting billet is H555mm×440mm×105mm.

[0015] Further, the size of the finished product is UBP305×305×223×12000mm.

[0016] Further, the mass percentage of the chemical composition of the high-strength steel pile for building structure comprises: C 0.16%, Si 0.38%, Mn 1.32%, P 0.012%, S 0.006%, V 0.06%, Re 0.014%, and the rest is Fe and inevitable impurities, and the mass fraction is 100%.

[0017] Further, the mass percentage of the chemical composition of the high-strength steel pile for building structure comprises: C 0.17%, Si 0.41%, Mn 1.31%, P 0.013%, S 0.007%, V 0.07%, Re 0.017%, and the rest is Fe and inevitable impurities, and the mass fraction is 100%.

[0018] Further, the mass percentage of the chemical composition of the high-strength steel pile for building structure comprises: C 0.16%, Si 0.39%, Mn 1.33%, P 0.014%, S 0.010%, V 0.08%, Re 0.016%, and the rest is Fe and inevitable impurities, and the mass fraction is 100%.

[0019] Further, the mass percentage of the chemical composition of the high-strength steel pile for building structure comprises: C 0.17%, Si 0.40%, Mn 1.34%, P 0.016%, S 0.004%, V 0.05%, Re 0.015%, and the rest is Fe and inevitable impurities, and the mass fraction is 100%.

[0020] Compared with the prior art, the beneficial technical effects of the present application are:

[0021] (1) By optimizing the chemical composition design and rolling process control, the high-strength steel pile of the present application has high yield strength (ReH≥590MPa) and tensile strength (Rm≥700MPa), and also has good impact toughness and plasticity, meeting the use requirements of building structure under high stress and complex working conditions.(2) By adding rare earth elements (Re) and optimizing the deoxidization and inclusion control process, the corrosion resistance and inclusion morphology of the steel are effectively improved, and the service life and reliability of the steel pile in marine environment and corrosive medium are improved.(3) By using high-efficiency smelting and rolling process (such as top and bottom combined blowing, white slag operation in refining and precise rolling control), energy consumption is reduced and process is stabilized, and raw material consumption and carbon emission are also reduced, which meets the trend of green building and sustainable development. DETAILED DESCRIPTION

[0022] The present application will be further described in detail below

[0023] The application discloses a production method of a high-strength steel pile for building structures, and the chemical composition of the high-strength steel pile comprises the following components in percentage by mass: C 0.15-0.18%, Si 0.35-0.45%, Mn 1.30-1.50%, P≤0.015%, S≤0.010%, V 0.05-0.08%, Re 0.010-0.020%, and the rest is Fe and inevitable impurities, and the total is 100%.

[0024] The application discloses a production process of a high-strength H-shaped steel pile for building structures, which comprises the following steps: converter smelting, LF refining, shaped blank continuous casting, casting blank stacking slow cooling, shaped blank heating, rough rolling, finish rolling, and control of finish rolling temperature and pass reduction.

[0025] Further, in the converter smelting process, low-sulfur molten iron is selected, top and bottom combined blowing technology is adopted, the final slag basicity is controlled to be 2.0-3.8, and the slag is blocked when tapping.

[0026] Further, the refining white slag operation is adopted, calcium carbide, silicon calcium barium and aluminum particles are used for slag adjusting, and the white slag is refined before the exit. After the molten steel is sampled, the oxygen content is controlled to be ≤20ppm. Argon is blown at the bottom throughout the process, the soft blowing lasts for not less than 15 minutes, and the refining period is at least 25 minutes, so that the refining quality is stable.

[0027] Further, the continuous casting adopts the full protection pouring process, a long water nozzle and a sealing ring are arranged in the ladle, and the flow is accurately controlled by using a stopper in the tundish. The casting blank pulling speed is set to be 0.7-1.0 m / min, and the overheating degree is controlled to be 15-30 DEG C, so that the water nozzle is prevented from being blocked, the pouring is smooth, the casting blank quality is uniform, and the high-quality shaped blank is provided for subsequent rolling.

[0028] The cross section size of the continuous casting blank is H555mm*440mm*105mm.

[0029] The shaped continuous casting blank enters the heating furnace under the digital control, and the heating process is started. In the process, the temperature of the casting blank is stabilized in the range of 1180-1250 DEG C, so that the internal organization of the casting blank is homogenized. The heat preservation time is controlled to be 200-230 minutes, so that the casting blank is fully heated. Immediately after the casting blank is heated and discharged, the high-pressure water device is used for descaling operation, so that the iron oxide scale attached to the surface of the casting blank is completely removed, and the casting blank enters the next link in a clean state.

[0030] Further, the rough rolling temperature is controlled to be 1100-1200 DEG C, the shaped blank is cooled by using water cooling, and the shaped blank is rolled for 3-5 passes. The shaped blank after the rough rolling is sent to the finish rolling machine station for continuous rolling.

[0031] Further: the temperature needs to be controlled at 920-1000℃ in the finishing rolling stage, the mode of waiting-temperature rolling combined with water cooling control is used, 5-7 passes are rolled, the final rolling temperature is stabilized at 850-900℃, the total reduction of the two-stage rolling is not less than 70%. After rolling, air cooling is firstly conducted, then concentrated cooling is conducted on the cooling bed, when the temperature is reduced to below 100℃, the product is moved to the straightening machine for straightening, and finally, the product is cut to size and baled.

[0032] Further: the finished product size is UBP305*305*223*12000mm.

[0033] Further: the surface quality of the high-strength steel pile for building structure is inspected, and the mechanical properties are also tested.

[0034] Example 1:

[0035] The production method of the high-strength steel pile for building structure is carried out according to the following steps:

[0036] The converter adopts low-sulfur molten iron, top and bottom combined blowing, and the final slag basicity is controlled at 2.5, the tapping process adopts aluminum-manganese iron deoxidizing alloying, and the slag is blocked during tapping.

[0037] In the refining process, the slag system is adjusted by using calcium carbide, silicon calcium barium and aluminum particles to ensure that the white slag state is reached before leaving the station. Sampling is detected immediately after the molten steel enters the station, and then the oxygen operation is carried out, and the oxygen content is strictly controlled below 20ppm. The whole refining process maintains bottom blowing argon operation, the soft blowing argon time is 18 minutes, and the total refining time is 30 minutes.

[0038] The continuous casting adopts full-process protection pouring, is equipped with a long nozzle and a sealing ring, the pouring flow is controlled by using a stopper in the tundish, the casting speed is set at 0.85m / min, and the superheat is kept at 25℃, and the molten steel is poured into an irregular billet.

[0039] The irregular continuous casting billet is heated at 1200℃ in the digital heating furnace, and the temperature is kept for 250 minutes, and the scale is removed by high-pressure water after the billet is discharged.

[0040] The rough rolling temperature is controlled at 1150℃, and after water cooling control, 3-5 passes are rolled, and then the product is sent to the finishing rolling machine for finishing rolling.

[0041] The finishing rolling temperature is kept at 970℃, the mode of waiting-temperature rolling combined with water cooling is adopted, 5-7 passes are rolled, the final rolling temperature is 880℃, and the total reduction is greater than or equal to 70%. After rolling, air cooling is conducted to below 100℃, and then the product is straightened, cut to size and baled.

[0042] Examples 2-4:

[0043] In examples 2-4, except that some specific process parameters are different from those in example 1, the rest are completely the same as those in example 1. The specific process parameters are shown in table 1.

[0044] Process parameters of each example in Table 1

[0045]

[0046] Comparative Example 1

[0047] Comparative Example 1 is identical to Example 1 except that no rare earth elements are added and the top and bottom combined blowing technique is not used.

[0048] Comparative Example 2

[0049] Comparative Example 2 is identical to Example 1 except that the Si content is increased and the Mn content is decreased. In this comparative example, the Si content is 0.50% and the Mn content is 1.10%.

[0050] Comparative Example 3

[0051] Comparative Example 3 is identical to Example 1 except that the top and bottom combined blowing technique is not used, the refining time is 10 minutes, and the final slag basicity is low (1.8).

[0052] Comparative Example 4

[0053] Comparative Example 4 is identical to Example 1 except that the final rolling temperature is high (970°C).

[0054] No obvious surface quality defects were found during the inspection of each example, and the surface quality was good. The properties of the rolled steel piles met the standard requirements. Table 2 shows the chemical composition of each example and comparative example, Table 3 shows the non-metallic inclusions and austenite grain size, and Table 4 shows the mechanical properties of each example and comparative example.

[0055] Table 2 Chemical composition of each example (mass percent / %)

[0056] Example C Si Mn P S V Re Example 1 0.16 0.38 1.32 0.012 0.006 0.06 0.014 Example 2 0.17 0.41 1.31 0.013 0.007 0.07 0.017 Example 3 0.16 0.39 1.33 0.014 0.010 0.08 0.016 Example 4 0.17 0.40 1.34 0.016 0.004 0.05 0.015 Comparative Example 1 0.16 0.37 1.31 0.012 0.006 0.07 —— Comparative Example 2 0.17 0.50 1.10 0.013 0.007 0.06 0.014 Comparative Example 3 0.16 0.40 1.33 0.014 0.005 0.08 0.015 Comparative Example 4 0.17 0.38 1.34 0.015 0.004 0.05 0.017

[0057] Table 3 Non-metallic inclusions and austenite grain size of each example

[0058]

[0059] Table 4 Mechanical properties of each example after rolling

[0060]

[0061] Through the comparison of the multiple comparative examples and the embodiments, the present application realizes the excellent balance of performance in the alloy composition design and the smelting process optimization, especially in the comprehensive improvement of the key indicators such as the yield strength, the tensile strength and the impact toughness. In contrast, the performance of the comparative examples fails to meet the overall standards, fully illustrating the technical improvement and the innovation of the present application. The difference is derived from the accurate optimization of the material composition and the process parameters, effectively solving the technical problems universally existing in the comparative examples.

[0062] From the above embodiments and comparative examples, it can be seen that: (1) the embodiments significantly improve the inclusion morphology of the steel material by adding rare earth elements (Re 0.010% ~ 0.020%), thereby improving the toughness of the steel material, especially showing higher reliability under complex working conditions. (2) The embodiments optimize the Si content (0.35% ~ 0.45%) and the Mn content (1.30% ~ 1.50%), thereby improving the strength while maintaining good plasticity and toughness, avoiding the increase in brittleness caused by excessive Si content and the insufficient low-temperature impact performance caused by low Mn content. (3) The embodiments use top and bottom combined blowing technology and prolong the refining time (≥25 minutes), effectively reducing the content of harmful impurities in the molten steel, significantly improving the purity and uniformity of the steel material, thereby improving the mechanical properties and surface quality of the finished product. (4) The embodiments control the finish rolling temperature at 850°C ~ 900°C, realizing the refinement of the grain and the homogenization of the structure, significantly improving the strength and toughness of the steel material, avoiding the performance degradation problem caused by excessively high finish rolling temperature.

[0063] The above-described embodiments only describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A method for producing high-strength steel piles for building structures, comprising the following processes: converter smelting, LF refining, continuous casting of shaped billets, slow cooling of billet stacking, heating of shaped billets, rough rolling, finish rolling, and control of final rolling temperature and reduction in each pass; characterized in that, Specifically: During the converter smelting process, low-sulfur molten iron is selected, and top and bottom blowing technology is adopted to control the final slag basicity at 2.0-3.

8. Slag is blocked during tapping. Aluminum-manganese ferroalloying is used for deoxidation to ensure the purity and quality of the molten steel. The white slag refining process employs calcium carbide, calcium-barium silicate, and aluminum granules for slag conditioning, refining the slag to white slag before it leaves the station. After molten steel is sampled upon arrival at the station, an oxygen determination process is performed, controlling the oxygen content to ≤20ppm. Argon is blown into the bottom throughout the process, with soft blowing lasting at least 15 minutes, and the refining cycle is at least 25 minutes to ensure stable refining quality. Continuous casting employs a fully protected casting process, with the ladle equipped with a long nozzle and sealing ring, and the tundish using a stopper rod to precisely control the flow rate. The billet casting speed is set at 0.7-1.0 m / min, and the superheat is controlled at 15-30℃ to prevent nozzle blockage, ensure smooth casting and uniform billet quality, and provide high-quality shaped billets for subsequent rolling. The irregularly shaped continuous casting billet enters the digitally controlled heating furnace to begin the heating process. During this process, the billet temperature must be stabilized between 1180 and 1250℃ to ensure homogenization of the internal structure of the billet. The holding time is controlled between 200 and 230 minutes to allow the billet to fully accumulate heat. The moment the billet is heated and removed from the furnace, it is immediately descaled using a high-pressure water device to thoroughly remove the iron oxide scale adhering to the surface of the billet, allowing the billet to enter the next stage in a clean state. The roughing temperature is controlled at 1100-1200℃ and cooled by water. The rolling process is carried out in 3-5 passes. The rough-rolled billet is then sent to the finishing mill for further rolling. During the finishing rolling stage, the temperature needs to be controlled at 920-1000℃. A combination of preheating rolling and water cooling is used, with 5-7 passes. The final rolling temperature is stabilized at 850-900℃, and the total reduction between the two rolling stages is not less than 70%. After rolling, the rolls are first air-cooled, then moved to a cooling bed for centralized cooling. Once the temperature drops below 100℃, the rolls are transferred to a straightening machine for straightening, and finally cut to length and bundled. The chemical composition of the high-strength steel piles used in the building structure comprises the following percentages by mass: C 0.15%–0.18%, Si 0.35%–0.45%, Mn 1.30%–1.50%, P ≤0.015%, S ≤0.010%, V 0.05%–0.08%, Re 0.010%–0.020%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.

2. The method for producing high-strength steel piles for building structures according to claim 1, characterized in that, The cross-sectional dimensions of the continuously cast billet are H555mm×440mm×105mm.

3. The method for producing high-strength steel piles for building structures according to claim 1, characterized in that, The finished product dimensions are UBP305×305×223×12000mm.

4. The method for producing high-strength steel piles for building structures according to claim 1, characterized in that, The chemical composition of the high-strength steel piles used in the building structure comprises the following percentages by mass: C 0.16%, Si 0.38%, Mn 1.32%, P 0.012%, S 0.006%, V 0.06%, Re 0.014%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.

5. The method for producing high-strength steel piles for building structures according to claim 1, characterized in that, The chemical composition of the high-strength steel piles used in the building structure comprises the following percentages by mass: C 0.17%, Si 0.41%, Mn 1.31%, P 0.013%, S 0.007%, V 0.07%, Re 0.017%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.

6. The method for producing high-strength steel piles for building structures according to claim 1, characterized in that, The chemical composition of the high-strength steel piles used in the building structure comprises the following percentages by mass: C 0.16%, Si 0.39%, Mn 1.33%, P 0.014%, S 0.010%, V 0.08%, Re 0.016%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.

7. The method for producing high-strength steel piles for building structures according to claim 1, characterized in that, The chemical composition of the high-strength steel piles used in the building structure comprises the following percentages by mass: C 0.17%, Si 0.40%, Mn 1.34%, P 0.016%, S 0.004%, V 0.05%, Re 0.015%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.

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