A heavy H-shaped steel and a manufacturing method of a thick-gauge high-strength heavy H-shaped steel satisfying a flaw detection standard requirement

Abstract

The application discloses a heavy H-shaped steel and a manufacturing method of thick-gauge high-strength heavy H-shaped steel meeting the flaw detection standard requirements, the heavy H-shaped steel comprises the following chemical components in percentage by weight: C 0.10-0.25%; Si 0.30-0.70%; Mn 1.30-1.70%; P≤0.035%; S≤0.035%; V 0.080-0.140%; Nb 0.010-0.060%; N≤300ppm; H≤5.0ppm, wherein the carbon equivalent CEV≤0.50%, Mn / S≥45, and Mn / Si≥4; the high-V micro-Nb alloying component design, refining steelmaking, secondary refining and continuous casting and other processes are adopted; the thick-gauge high-strength heavy H-shaped steel produced by the method meets the requirements of the single defect indication length or width: width < 20mm, length < 50mm, and the flaw detection performance is qualified.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of H-shaped steel, and particularly relates to a heavy H-shaped steel and a manufacturing method of thick-gauge high-strength heavy H-shaped steel meeting the requirements of flaw detection standards. BACKGROUND

[0002] The thick-gauge high-strength heavy H-shaped steel is rolled by using a near-final-shaped special-shaped blank, and due to the large section size of the heavy H-shaped steel special-shaped blank, such as a size of 1300mm*510mm*140mm*180mm, improper control of steelmaking composition, temperature and continuous casting process can easily cause defects such as loose R-angle area of the blank and internal cracks in the web.

[0003] After the heavy H-shaped steel special-shaped blank is hot-rolled, when thick-gauge products are produced, due to high strength, about 0.10% of V and Nb elements need to be added for alloying, and high V and high Nb components are prone to cause cracks in the blank during the production process. In the hot-rolling process of the thin-gauge heavy H-shaped steel special-shaped blank, under the condition of large compression ratio, the internal defects such as loose and cracks in the blank can be welded, and the flaw detection performance can meet the standard requirements. The maximum allowable single defect indication length or width requirement in the flaw detection standard for part of the heavy H-shaped steel for large buildings is: width≤20mm, length≤50mm.

[0004] However, when thick-gauge heavy H-shaped steel products with a flange thickness≥50mm are produced, due to the small compression ratio of the special-shaped blank, the internal defects such as loose and cracks in the blank are inherited to the heavy H-shaped steel products, and the produced heavy H-shaped steel has a large number of unqualified problems in flaw detection, which causes large building projects to be unable to use. To solve the problems of thick-gauge blank center loose and cracks, the traditional method is to use end electromagnetic stirring or light-heavy press-down technology for continuous casting. This technology has been maturely used in the fields of square billets, round billets and slab billets, but due to the complex section structure of the special-shaped blank, these technologies for solving the problems of center loose and cracks in the blank are still blank in the field of heavy special-shaped blank production.

[0005] At present, only a few foreign enterprises have the ability to produce heavy H-shaped steel, and there are few reports on heavy H-shaped steel products that can meet the requirements. There is no similar product production in China, and the improvement of the flaw detection qualified rate of heavy H-shaped steel is in the research and exploration stage.

[0006] Chinese patent CN 107876721A discloses a special-shaped blank web center crack control method, and the disclosed section size of the special-shaped blank continuous casting machine is 295mm*205mm*85mm-430mm*300mm*85mm; the base circular arc radius of the casting machine is 9-12m; the secondary cooling zone includes three cooling zones of foot roller section, secondary cooling zone section one and secondary cooling zone section two, and the distance between the casting blank support system outlet and the meniscus of the crystallizer is 4-6m. The special-shaped blank produced by the patent belongs to the field of small H-shaped steel.

[0007] The document 'Principle Analysis and Measures of Plate Rolling Defect' proposes that the causes of the defect are hydrogen-induced cracks, center segregation of the casting blank, internal inclusions of the casting blank and developed center banded structure, etc., and the document mainly solves the problem of plate defect.

[0008] The above prior art is only limited to the field of casting machines and small H-shaped steel of the profiled blank, and the profiled blank of the small H-shaped steel has a large difference in the heavy profiled blank and belongs to different grades of H-shaped steel products. SUMMARY

[0009] To solve the above technical problems, the present application provides a heavy H-shaped steel and a manufacturing method of a thick-gauge high-strength heavy H-shaped steel meeting the flaw detection standard requirements, solves the problem of unqualified flaw detection of thick-gauge high-strength heavy H-shaped steel products, replaces the traditional welded H-shaped steel products, and meets the design requirements of large-scale construction projects.

[0010] The technical scheme adopted by the present application is as follows:

[0011] The present application provides a heavy H-shaped steel, which comprises the following chemical components by weight percentage: C 0.10% to 0.25%; Si 0.30% to 0.70%; Mn 1.30% to 1.70%; P≤0.035%; S≤0.035%; V 0.080% to 0.140%; Nb 0.010% to 0.060%; N≤300ppm; H≤5.0ppm; the balance being iron and unavoidable impurities, wherein the carbon equivalent CEV≤0.50%, Mn / S≥45, and Mn / Si≥4.

[0012] The heavy H-shaped steel preferably comprises the following chemical components by weight percentage: C 0.14% to 0.22%; Si 0.35% to 0.65%; Mn 1.35% to 1.65%; P≤0.032%; S≤0.032%; V 0.085% to 0.120%; Nb 0.015% to 0.045%; N≤260ppm, H≤4.0ppm; the balance being iron and unavoidable impurities, wherein the carbon equivalent CEV≤0.48%.

[0013] The calculation formula of the carbon equivalent is CEV(%)=C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15.

[0014] The heavy H-shaped steel has a metallographic structure of ferrite, bainite and pearlite, wherein the ferrite grain size grade is above 9.0, and the volume percentage of the bainite and the pearlite is not less than 22%.

[0015] The yield strength R eL of the heavy H-shaped steel is not less than 400MPa, the tensile strength Rm No less than 500 MPa, elongation A no less than 18%, and KV2 no less than 27 J at 0 ℃.

[0016] The application further provides a manufacturing method of the thick-gauge high-strength heavy H-shaped steel meeting the flaw detection standard requirement, which comprises the following steps: obtaining the heavy-shaped bloom of the heavy H-shaped steel through smelting and continuous casting, and obtaining the thick-gauge high-strength heavy H-shaped steel meeting the flaw detection standard requirement through rolling of the heavy-shaped bloom.

[0017] In the continuous casting step, the copper plate is used for pouring ≤300 furnaces, and the use frequency of the support 1 segment, the support 2 segment and the support 3 segment of the fan-shaped segment is ≤400 furnaces, so that the wear of the coating of the crystallizer and the taper deformation can be avoided due to the excessive use frequency; and the use frequency of the fan-shaped segment is strictly controlled to avoid the increase of the roll spacing and the blockage of the fan-shaped segment, so that the deformation of the outer shape size of the cast blank, the deterioration of the internal quality and the problem of the flaw detection of the cast blank can be prevented. The argon protection is performed during the whole pouring process, the insertion depth of the nozzle during the pouring process is controlled to be 80-120 mm, the liquid level of the tundish is rapidly increased to ≥12 tons at the beginning of pouring, so that the stable flow field of the crystallizer can be controlled, the slag rolling during the pouring process can be avoided, the quality of the cast blank cannot meet the rolling requirement, and the problem of the flange cracking can be avoided; in order to reduce the R angle center porosity and the web crack of the heavy-shaped bloom, the low pulling speed and the weak cooling mode of the secondary cooling water are adopted for control, the continuous casting machine has a continuous casting pulling speed range of 0.40-0.70 m / min, the superheat control range is 15-30 ℃, and the total pressure control range of the secondary cooling water is 10.0-13.0 bar; and the heavy-shaped bloom is obtained after the fire cutting.

[0018] The argon protection during the whole pouring process refers to that the argon protection is performed during the tundish transfer process during pouring, the argon protection is performed during the pouring of the tundish protection sleeve, and the argon protection is performed for the tundish of the heavy-shaped bloom continuous casting machine before pouring, so that the oxidation of the molten steel due to the contact with air, the increase of the internal inclusions of the cast blank and the inclusion defects of the cast blank after hot rolling can be avoided, the product quality is affected, the internal defects are increased, and the problem of the flaw detection failure can be avoided.

[0019] The continuous casting pulling speed range of the continuous casting machine is preferably 0.45-0.65 m / min.

[0020] The cross-sectional specification of the heavy-shaped bloom is high*wide*web thickness*flange thickness=1300 mm*510 mm*140 mm*180 mm; the weight of the heavy-shaped bloom reaches 2.833 t, and the heavy-shaped bloom is the largest cross-section-shaped bloom in China.

[0021] The rolling process employs five passes: the first pass temperature ≤1000℃, the third pass temperature ≤980℃, and the fifth pass temperature ≤960℃, with a rolling speed ≤4.0 m / s. During rolling, all cooling water for the lower web of the universal section is turned on, and the side nozzles, upper nozzle, and lower nozzle are all open. The rolling pressure is ≥1.3 MPa. By matching the rolling temperature, speed, and cooling process, the rolling process is ensured to be stable, which can improve minor internal defects in the billet, refine the grains, and improve mechanical properties. Excessive temperature, excessive rolling speed, and uneven cooling can amplify internal defects during the rolling of heavy-duty shaped billets, leading to internal cracks in heavy H-beams and resulting in non-compliance of the heavy H-beam product during flaw detection.

[0022] The smelting process includes the following steps in sequence: KR molten iron pretreatment and desulfurization, converter smelting, and LF furnace refining.

[0023] In the KR molten iron pretreatment desulfurization step, the target S content of the desulfurized molten iron is ≤0.010%, and the bright surface of the molten iron after slag removal is ≥80%.

[0024] In the converter smelting step, the converter tapping temperature is controlled at 1600℃~1650℃, the converter tapping steel C≥0.07%, the converter tapping steel P≤0.030%, and the converter tapping steel S≤0.030%.

[0025] In the converter smelting process, argon is blown from the bottom at the beginning of the converter tapping process. The temperature of the molten steel is measured after entering the argon blowing station, and the argon blowing time is ≥3min.

[0026] In the LF furnace refining process, argon is blown into the bottom of the ladle, and alloys are added according to the composition design requirements. Argon blowing and strong stirring are carried out for 3 to 10 minutes, and temperature and sampling are performed. After the composition and temperature meet the design requirements, the ladle is discharged from the station. The target time from refining entry to exit is ≤30 minutes, and the heating time is ≤15 minutes. The refining composition control requirements are Mn / S≥45 and Mn / Si≥4. This can avoid R-angle shrinkage cavities and internal cracks in the web, which would lead to the failure of the flaw detection of the finished heavy H-beams after hot rolling.

[0027] The finished heavy H-beam has the following specifications: height × width × web thickness × flange thickness = 600mm × 476mm × 100mm × 140mm, and a weight of 1299kg per meter. It is the largest special-shaped billet in China and has strict requirements for the cooling process during continuous casting. If the production is not carried out in accordance with the processes required by this invention, the pass rate of flaw detection of the hot-rolled heavy H-beam cannot meet the production standard requirements.

[0028] The functions and controls of each component in the heavy H-beam provided by this invention are as follows:

[0029] C: Increased carbon content leads to higher strength and hardness in steel, but lower plasticity and toughness. While maintaining strength, reducing carbon content improves the toughness and cold-working properties of steel; therefore, this invention controls the carbon content to 0.10%–0.25%.

[0030] Si: Appropriately increasing the silicon content in heavy shaped billets is beneficial to the comprehensive mechanical properties of steel and also increases the corrosion resistance of steel. In this invention, the Si content is controlled at 0.30% to 0.70%.

[0031] Mn: An important alloying element for improving the strength and toughness of heavy H-beams. It can be infinitely dissolved in Fe, and while increasing the strength of steel, its impact on plasticity is relatively small. When the Mn content exceeds 1.5%, it promotes the formation of bainite. In order to improve the rolling performance of heavy special-shaped billets, this invention requires Mn / S ≥ 60 and Mn / Si ≥ 4, which helps to reduce crack defects that occur during the rolling process.

[0032] P: It has a very strong solid solution strengthening and work hardening effect. It segregates severely in steel, which increases the cold brittleness of steel and makes it susceptible to acid corrosion. For heavy H-beams with high quality requirements, the phosphorus content in the steel should be ≤0.035%.

[0033] S: The presence of sulfur causes hot brittleness and rusting in steel, and it is a harmful impurity element. Therefore, the sulfur content of heavy H-beams should be ≤0.035%, and for large-scale construction projects with high design service life requirements, the sulfur content of heavy H-beams should be ≤0.032%.

[0034] V and Nb primarily function to refine grains in steel. Through the dispersed precipitation of their carbonitriding particles and the solid solution of Nb and V, they significantly improve the strength and toughness of the steel. Therefore, adding two microalloying elements, Nb and V, to heavy shaped billets, while ensuring a certain N content, is beneficial for improving the strength of the finished heavy H-beams. Because the thick-gauge heavy H-beams produced by this invention require high strength, the total V+Nb content reaches the range of 0.100–0.150%. The addition of high V and Nb content can easily lead to defects such as cracks during the continuous casting process of heavy shaped billets, resulting in unsatisfactory flaw detection performance.

[0035] Nitrogen (N): Increased nitrogen content significantly increases the strength of steel, but also significantly reduces its plasticity, especially toughness, worsens weldability, and exacerbates cold brittleness. It also increases aging tendency, cold brittleness, and hot brittleness, impairing the weldability and cold bending performance of the steel. This invention uses a VN alloy to increase nitrogen content, which also increases the nitrogen content in the molten steel. Ultimately, VN forms within the steel, inhibiting grain growth and providing dispersion strengthening. While increasing nitrogen content improves mechanical properties, it can also cause cracking during rolling. This invention requires nitrogen content to be controlled ≤300ppm to meet rolling requirements while providing strengthening.

[0036] Hydrogen (H): The most harmful element in steel. Dissolved hydrogen in steel can cause defects such as hydrogen embrittlement and white spots. Like oxygen and nitrogen, hydrogen has extremely low solubility in solid steel. At high temperatures, it dissolves into molten steel, and during cooling, it cannot escape in time, accumulating in the microstructure to form high-pressure micropores. This drastically reduces the steel's plasticity, toughness, and fatigue strength, and in severe cases, can cause cracks and brittle fracture. To reduce the H content in steel, dry raw materials are used in production, and the casting process is protected to prevent H accumulation in the continuous casting ladle. This invention controls H to ≤ 5.0 ppm.

[0037] This invention employs a high-V, micro-Nb alloying composition design. Based on the requirements of large-scale construction projects for the mechanical properties and internal quality of heavy H-beams, it refines processes such as steelmaking, ladle refining, and continuous casting. In particular, the continuous casting process utilizes low casting speed and a secondary cooling water weak cooling mode to reduce porosity at the center of the heavy irregular-shaped billet's radius (R-angle) and web cracks. After rolling on a heavy-duty universal rolling mill, the required yield strength (R) is achieved. eL Not less than 400MPa, tensile strength R m The steel profile provided by this invention has a strength of not less than 500 MPa, an elongation A of not less than 18%, and a KV2 of not less than 27 J at 0℃. After infrared flaw detection testing, the length or width of a single defect indication meets the requirements: width < 20 mm, length < 50 mm, indicating it is a high-strength, thick-gauge flaw detection qualified product. Attached Figure Description

[0038] Figure 1 Metallographic diagram of the H-beam produced in Example 1; Detailed Implementation

[0039] This invention provides a heavy-duty H-beam, which comprises the following chemical composition by weight percentage: C 0.10%–0.25%; Si 0.30%–0.70%; Mn 1.30%–1.70%; P ≤ 0.035%; S ≤ 0.035%; V 0.080%–0.140%; Nb 0.010%–0.060%; N ≤ 300 ppm; H ≤ 5.0 ppm; the balance being iron and unavoidable impurities, wherein the carbon equivalent (CEV) is ≤ 0.50%, Mn / S ≥ 45, and Mn / Si ≥ 4.

[0040] The manufacturing method of the heavy H-beam is as follows:

[0041] 1) KR molten iron pretreatment and desulfurization: Thick-gauge heavy H-beam products have certain requirements for the sulfur content of molten iron. When the sulfur content of molten iron exceeds 0.035%, the molten iron is pretreated at the KR desulfurization station before being added to the converter. The target sulfur content of the desulfurized molten iron is ≤0.010%, and the bright surface of the molten iron after slag removal is ≥80%.

[0042] 2) Converter steelmaking: Steelmaking is carried out in a converter. During the tapping process, refining slag, lime, ferroaluminum, medium carbon ferromanganese and ferrosilicon and other auxiliary materials and alloys are added at once. The tapping temperature of the converter is controlled within the range of 1600℃~1650℃. The carbon content of the converter tapping steel is ≥0.07%, the phosphorus content is ≤0.030%, and the sulfur content is ≤0.030%. The composition of the converter tapping steel is adjusted to the target control range.

[0043] 3) Argon station: Argon is blown from the bottom at the beginning of the converter tapping process. The temperature of the molten steel is measured after it enters the argon blowing station. The argon blowing time is required to be ≥3min. The composition of the molten steel is measured before it leaves the station.

[0044] 4) LF furnace refining: Argon is blown into the bottom of the ladle, and alloys such as ferrovanadium and ferroniobium are added according to the composition design requirements. Argon is blown and stirred strongly for 3 to 10 minutes, and temperature is measured and samples are taken. After the composition and temperature meet the design requirements, the ladle is discharged from the station. In order to control the increase of N, O and H gas element content during the refining process, the target time from refining entry to exit from the station is required to be ≤30 minutes, and the heating time is required to be ≤15 minutes. The refining composition control requirements are Mn / S≥45 and Mn / Si≥4.

[0045] 5) Heavy-duty shaped billet continuous casting: This invention focuses on solving low-magnification quality problems such as porosity in the R-angle area and central web cracks in heavy-duty shaped billets. It requires precise control of the continuous casting equipment and production process. For the production of thick-gauge heavy H-beams, it requires the use of copper plates with a capacity of ≤300 heats for casting. The number of uses for support sections 1, 2, and 3 in the fan-shaped section should all be ≤400 heats. Argon blowing protection is applied during the ladle transfer process, and argon blowing protection is also applied to the ladle's protective sleeve during casting. Before casting begins, argon blowing protection is applied to the tundish of the heavy-duty shaped billet continuous casting machine. During the casting process, the nozzle insertion depth is controlled at 80–120 mm. At the start of casting, the molten steel level in the tundish is rapidly raised to ≥12 tons to begin casting. The continuous casting speed range of the heavy-duty shaped billet continuous casting machine is optimized from 0.40 to 0.70 m / min to 0.45 to 0.65 m / min. Low superheat casting is used, with superheat control ranging from 15 to 30°C. Weak cooling control is employed in the secondary cooling section, and the total pressure of the secondary cooling water is controlled within the range of 10.0 to 13.0 bar. After heat cutting, a fixed-length heavy-duty shaped billet with cross-sectional dimensions of 1300 mm × 510 mm × 140 mm × 180 mm (height × width × web thickness × flange thickness) is obtained. This heavy-duty shaped billet has a weight of 2.833 t per meter, making it the largest cross-sectional shaped billet unique in China.

[0046] 6) Hot rolling of thick-gauge heavy H-beams: Rolled by a heavy universal rolling mill in 5 passes, with the rolling temperature of the first pass ≤1000℃, the rolling temperature of the third pass ≤980℃, the rolling temperature of the fifth pass ≤960℃, and the rolling speed ≤4.0m / s; during the rolling process, the cooling water of the lower web of the universal section is fully opened, and the side nozzles, upper nozzles and lower nozzles are all opened, with the rolling pressure ≥1.3MPa.

[0047] The present invention will now be described in detail with reference to the embodiments.

[0048] The composition control of Examples 1 to 7 and Comparative Examples 1 to 3 in this invention is shown in Table 1, the process and billet quality control results are shown in Tables 2 and 3, and the mechanical properties and flaw detection results are shown in Table 4.

[0049] Table 1. Composition control of thick-gauge high-strength heavy-duty H-beams (wt%); N and H in ppm

[0050] Ingredients C Si Mn P S V Nb N H CEV Example 1 0.18 0.45 1.52 0.030 0.027 0.098 0.038 228 3.7 0.45 Example 2 0.14 0.52 1.48 0.025 0.019 0.102 0.015 210 3.5 0.41 Example 3 0.19 0.36 1.60 0.022 0.029 0.110 0.045 236 3.1 0.48 Example 4 0.22 0.35 1.48 0.032 0.032 0.090 0.038 258 3.7 0.48 Example 5 0.19 0.48 1.45 0.018 0.030 0.094 0.040 243 4.0 0.45 Example 6 0.21 0.65 1.52 0.020 0.018 0.103 0.036 260 3.6 0.48 Example 7 0.21 0.54 1.47 0.023 0.027 0.105 0.035 255 3.9 0.48 Comparative Example 1 0.22 0.70 1.62 0.035 0.03 0.115 0.050 280 4.2 0.51 Comparative Example 2 0.21 0.30 1.49 0.038 0.039 0.085 0.014 258 3.7 0.48 Comparative Example 3 0.22 0.43 1.30 0.027 0.035 0.094 0.026 249 3.9 0.46

[0051] Table 2 Production Process Control of Thick-Spec High-Strength Heavy-Duty H-Beam Steel Billets

[0052]

[0053]

[0054] Table 3. Production Process Control of Thick-Spec High-Strength Heavy H-Beams in Hot Rolling

[0055]

[0056] Heavy H-beams produced from heavy shaped billets through subsequent processing have the following mechanical property requirements: yield strength ReL not less than 400MPa, tensile strength Rm not less than 500MPa, elongation A not less than 18%, and KV2 not less than 27J at 0℃. Infrared flaw detection tests were also performed on the R-angle region and web of the examples and comparative examples.

[0057] Table 4 Performance Control of Thick-Spec High-Strength Heavy H-Beams

[0058]

[0059]

[0060] The thick-gauge high-strength heavy-duty shaped billets produced using Examples 1 to 7 above exhibit excellent quality and a good surface finish. Low-magnification analysis shows that the central porosity is ≤1.0 mm, central segregation is ≤1.0 mm, and corner cracks are ≤1.0 mm. There are no quality issues such as subcutaneous cracks, intermediate cracks, central cracks, or subcutaneous bubbles. The billets manufactured using this invention, after processes including heating furnace, hot rolling, controlled cooling, and finishing, produce thick-gauge high-strength heavy-duty H-beams that meet the required yield strength R. eL 460~490MPa, tensile strength R mThick-gauge high-strength heavy H-beams with a strength of 560-600MPa, an elongation A of not less than 23%, and a KV2 of not less than 75J at 0℃, after infrared flaw detection testing, have a single defect indication length or width that meets the requirements: width < 20mm, length < 50mm, and are qualified products with high-strength thick-gauge flaw detection performance.

[0061] The thick-gauge, high-strength, heavy-duty shaped billets produced using Comparative Examples 1 to 3 exhibit excellent quality and good surface finish. Low-magnification analysis shows that the central porosity is ≤1.5 mm, central segregation is ≤1.0 mm, and corner cracks are ≤1.5 mm. No subcutaneous cracks, intermediate cracks, central cracks, or subcutaneous bubbles are found. The heavy-duty H-beams produced from the billets manufactured using these comparative examples, after furnace heating, hot rolling, controlled cooling, and finishing processes, have a yield strength R... eL Not less than 400MPa, tensile strength R m Thick-gauge high-strength heavy H-beams with an elongation of not less than 17% and a KV2 of not less than 27J at 0℃, are deemed unqualified after infrared flaw detection if cracks with a width > 20mm and a length > 50mm are found in the R-angle area and the middle of the web.

[0062] The above detailed description of a heavy H-beam and a method for manufacturing a thick, high-strength heavy H-beam that meets the requirements of flaw detection standards, with reference to the embodiments, is illustrative rather than limiting. Several embodiments can be listed within the defined scope. Therefore, variations and modifications that do not depart from the overall concept of the present invention should be within the protection scope of the present invention.

Claims

1. A thick-gauge, high-strength, heavy-duty H-beam that meets flaw detection standards, characterized in that: The heavy H-beams comprise the following chemical composition by weight percentage: C 0.10%~0.25%; Si 0.30%~0.70%; Mn 1.30%~1.70%; P≤0.035%; S≤0.035%; V 0.080%~0.140%; Nb 0.010%~0.060%; N≤300ppm; H≤5.0ppm; the balance being iron and unavoidable impurities, wherein the carbon equivalent CEV≤0.50%, Mn / S≥45, and Mn / Si≥4; The manufacturing method of the thick-gauge high-strength heavy H-beam that meets the flaw detection standard includes the following steps: obtaining a heavy shaped billet of the heavy H-beam with the chemical composition by smelting and continuous casting, and then rolling the heavy shaped billet to obtain the thick-gauge high-strength heavy H-beam that meets the flaw detection standard. The smelting process includes the following steps in sequence: KR hot metal pretreatment and desulfurization, converter smelting, and LF furnace refining; In the KR molten iron pretreatment and desulfurization step, the target S content of the desulfurized molten iron is ≤0.010%; In the converter smelting step, the converter tapping temperature is controlled at 1600℃~1650℃, the converter tapping steel C≥0.07%, the converter tapping steel P≤0.030%, and the converter tapping steel S≤0.030%; In the LF furnace refining process, argon is blown into the bottom of the ladle, alloys are added according to the composition design requirements, argon blowing and strong stirring are performed for 3 to 10 minutes, temperature is measured and samples are taken, and the ladle is discharged after the composition and temperature meet the design requirements; the heating time is ≤15 minutes. During the continuous casting process, the casting speed of the continuous casting machine ranges from 0.40 to 0.70 m / min; the total pressure of the secondary cooling water is controlled within the range of 10.0 to 13.0 bar. In the rolling process, five passes are used, with the first pass temperature ≤1000℃, the third pass temperature ≤980℃, the fifth pass temperature ≤960℃, and the universal section pressure ≥1.3MPa.

2. The thick-gauge high-strength heavy H-beam meeting the flaw detection standards as described in claim 1, characterized in that, The metallographic structure of the heavy H-beam is ferrite, bainite and pearlite, wherein the ferrite grain size grade is above 9.0 and the volume percentage of bainite and pearlite is not less than 22%.

3. The thick-gauge high-strength heavy H-beam meeting the flaw detection standards as described in claim 1, characterized in that, The yield strength R of the heavy H-beam eL Not less than 400MPa, tensile strength R m Not less than 500MPa, elongation A not less than 18%, KV2 not less than 27J at 0℃.

4. A method for manufacturing thick-gauge high-strength heavy H-beams that meet flaw detection standards, characterized in that, The manufacturing method includes the following steps: smelting and continuous casting to obtain a heavy shaped billet of heavy H-beam as described in claim 1, and rolling the heavy shaped billet to obtain thick-gauge high-strength heavy H-beam that meets the requirements of flaw detection standards. In the continuous casting process, copper plates with a capacity of ≤300 heats are used for casting, and the number of times the sector support section 1, support section 2, and support section 3 are used is ≤400 heats. Argon gas protection is carried out throughout the casting process, and the insertion depth of the tundish nozzle is controlled at 80~120mm. When casting begins, the liquid level of the molten steel in the tundish is quickly raised to ≥12 tons. The superheat is controlled within the range of 15~30℃. After fire cutting, heavy special-shaped billets are obtained.

5. The manufacturing method according to claim 4, characterized in that, During the rolling process, the rolling speed is ≤4.0m / s; the cooling water for the lower web of the universal section is fully turned on, and the side nozzles, upper nozzles, and lower nozzles are all turned on.

6. The manufacturing method according to claim 4, characterized in that, The smelting process includes the following steps in sequence: KR hot metal pretreatment desulfurization, converter smelting, LF furnace refining.

7. The manufacturing method according to claim 6, characterized in that, In the KR molten iron pretreatment desulfurization step, the slag removal bright surface of the molten iron is ≥80%.

8. The manufacturing method according to claim 6, characterized in that, In the converter smelting process, argon is blown from the bottom at the beginning of the converter tapping process. The temperature of the molten steel is measured after entering the argon blowing station, and the argon blowing time is ≥3min.

9. The manufacturing method according to claim 6, characterized in that, In the LF furnace refining step, the target time from refining entry to exit is ≤30min; the refining composition control requirements are Mn / S≥45 and Mn / Si≥4.

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