460mpa grade super-thick hot-rolled h-shaped steel and production method thereof

Abstract

The application provides a 460MPa grade super-thick hot-rolled H-shaped steel and a production method thereof, and the composition of the steel is as follows: C: 0.10-0.20%, Si: 0.30-0.50%, Mn: 0.8%-1.50%, P: ≤0.015%, S: ≤0.005%, Nb: 0.010-0.050%, V: 0.040%-0.100%, Ti: 0.006%-0.020%, Cr: 0.10%-0.30%, N: 0.0060%-0.0120%, and the rest is Fe and inevitable impurities, 0.35%≤C+Mn / 6≤0.45%, 0.060%≤Nb+V≤0.130%. In the production, a billet slow cooling area is arranged after the billet is continuously cast, and the drawn pile of billets is slowly cooled through a specific process, and then the controlled rolling and controlled cooling are carried out, so that the production difficulty of the super-thick high-strength hot-rolled H-shaped steel is solved, and the composition is low and the performance is excellent.

Description

Technical Field

[0001] This invention belongs to the field of hot-rolled H-beam production technology, and more specifically, relates to a 460MPa grade extra-thick hot-rolled H-beam and its production method. Background Technology

[0002] Extra-thick hot-rolled H-beams refer to hot-rolled H-beams with a flange thickness greater than 60mm. When producing extra-thick hot-rolled H-beams, due to the influence of production equipment and related technologies, ultra-large special-shaped billets with a flange thickness of 150mm-210mm are usually used as billets. The quality control of such special-shaped billets is much more difficult than that of small and medium-sized special-shaped billets, resulting in large fluctuations in the mechanical properties of the finished extra-thick hot-rolled H-beams.

[0003] Furthermore, with the increase in flange thickness of hot-rolled H-beams, the mechanical properties of the products are more difficult to improve due to the thickness effect. Currently, the yield strength of extra-thick hot-rolled H-beams with flange thickness greater than 60mm is mainly 355MPa, while there is currently no product with a yield strength of 460MPa.

[0004] With the increasing construction of super high-rise buildings, long-span bridges, and large stadiums, 460MPa grade extra-thick hot-rolled H-beams will become a key material for their supporting structures. In summary, extra-thick high-strength hot-rolled H-beams have broad application prospects, but related production technologies are currently lacking. Therefore, to address the shortcomings of existing technologies, it is urgent to develop a set of key production technologies for this type of product.

[0005] Patent CN 104630625 A, published on May 20, 2015, discloses a low-temperature resistant hot-rolled H-beam and its preparation method. The chemical composition of the hot-rolled H-beam is (wt%): C: 0.07–0.10%, Si: 0.2–0.4%, Mn: 1.30–1.60%, P≤0.020%, S≤0.015%, V: 0.015–0.070%, Ti: 0.010–0.030%, with the balance being Fe and unavoidable impurities. The production method includes converter smelting, LF furnace refining, continuous casting, and rolling. The H-beam prepared by this invention has a microstructure of polygonal ferrite and pearlite, and a yield strength of 350–450 MPa. This patented rolling process uses conventional methods, and the chemical composition is designed to achieve a post-rolling yield strength of 450MPa, an elongation at break of more than 22%, and a V-notch impact energy of more than 200J at -40℃. This invention is suitable for the production of high-strength, low-temperature resistant hot-rolled H-beams under 40mm in diameter, but not for the production of extra-thick hot-rolled H-beams over 60mm in diameter with a strength of 460MPa.

[0006] Patent CN 110016611 A, published on July 16, 2019, discloses a weather-resistant and low-temperature-resistant hot-rolled H-beam with a yield strength of 355 MPa. Its chemical composition by mass percentage includes: C: 0.08%–0.14%, Si: 0.35%–0.50%, Mn: 1.00%–1.15%, P≤0.020%, S≤0.015%, Cr: 0.40%–0.50%, Cu: 0.30%–0.40%, Ni: 0.30%–0.40%, Nb: 0.03%–0.05%, Al: 0.020%–0.040%, with the remainder being Fe and impurities, totaling 100% by mass. The patent also discloses a method for producing weather-resistant and low-temperature resistant hot-rolled H-beams with a yield strength of 355MPa using 280mm×380mm rectangular billets. This method successfully develops weather-resistant hot-rolled H-beams with good low-temperature toughness using rectangular billets. The invention incorporates 0.30–0.40% Ni, 0.40%–0.50% Cr, and 0.30%–0.40% Cu. The resulting hot-rolled H-beams exhibit good weather resistance and low-temperature toughness, but their strength level is only 355MPa, making them unsuitable for producing extra-thick hot-rolled H-beams with a strength of 460MPa or more (over 60mm).

[0007] The patent published on October 12, 2018, with publication number CN 108642381 A, discloses a hot-rolled high-toughness low-temperature resistant H-beam with a yield strength of 460MPa and its preparation method. The H-beams involved in this patent employ a nitrogen-containing composite microalloying design. Their chemical composition by weight percentage is: C: 0.03%–0.07%, Si≤0.3%, Mn: 1.20%–1.40%, Nb: 0.015%–0.030%, V: 0.10%–0.15%, Ti: 0.015%–0.025%, Ni: 0.25%–0.45%, Cr: 0.30%–0.50%, Als: 0.01%–0.06%, N: 0.010%–0.023%, P≤0.015%, S≤0.010%, O≤0.004%, with the remainder being Fe and unavoidable impurities. This allows for the achievement of strengths exceeding 460 MPa on ordinary hot-rolled H-beams while maintaining high strength and toughness. After rolling, its yield strength can reach 460 MPa, tensile strength can reach 600 MPa, and elongation ≥18%; the longitudinal impact energy at -40℃ can reach 100 J. This invention incorporates 0.015%–0.030% Nb, 0.10%–0.15% V, 0.015%–0.025% Ti, 0.25%–0.45% Ni, and 0.30%–0.50% Cr, achieving a strength level of 460 MPa and a longitudinal impact energy of 100 J at -40℃. However, its composition design cost is high, its economic efficiency is poor, and it is not conducive to actual industrial production.

[0008] Patent CN 103966507 A, published on August 6, 2014, discloses an extra-thick, low-temperature resistant hot-rolled H-beam with a yield strength of 275 MPa and its production method. The flange thickness is 26 mm ≤ flange thickness ≤ 35 mm. Its chemical composition by weight percentage is: C: 0.12%–0.17%, Si: 0.10%–0.30%, Mn: 0.90%–1.40%, P ≤ 0.02%, S ≤ 0.015%, V: 0.01–0.03%, Ti: 0.005–0.020%, with the remainder being iron and unavoidable impurities. The mechanical properties and longitudinal impact energy at -20℃ of the extra-thick, low-temperature resistant hot-rolled H-beam with a yield strength of 275 MPa provided by this invention fully meet the technical requirements for 275 MPa grade extra-thick, low-temperature resistant hot-rolled H-beams. The hot-rolled H-beams produced by this method have a thickness of 26-35 mm and a strength grade of 275 MPa. They are not suitable for the production of extra-thick hot-rolled H-beams with a thickness of 60 mm or more and a strength grade of 460 MPa.

[0009] Patent CN 109972042 A, published on July 5, 2019, discloses a low-temperature corrosion-resistant H-beam with a yield strength of 800 MPa and its preparation method. The chemical composition by mass percentage (%) is: C: 0.10–0.20; Si: 0.20–0.40; Mn: 1.20–1.60; Ni: 0.2–0.4; Cr: 0.2–0.6; V: 0.06–0.10; Nb: 0–0.04; Ti: 0.01–0.02; N: 100–150 ppm, P ≤ 0.020, S ≤ 0.020, with the balance being Fe and unavoidable impurities. The preparation process involves first preparing a billet, then hot rolling, followed by quenching and tempering. The hot rolling temperature is 1180–1150℃, and the final rolling temperature is 800℃–890℃. The quenching temperature is 900℃, and the cooling rate is 30~100℃ / s. The tempering temperature is 450℃~600℃. The resulting H-beams have a yield strength ≥800MPa, a tensile strength of 860~940MPa, an elongation after fracture ≥14.0%, and a low-temperature impact strength of ≥50J at -20℃. While this method can produce hot-rolled H-beams with a yield strength of up to 800MPa, the use of a tempering process undoubtedly increases production costs.

[0010] Patent CN 103938079 A, ​​published on July 23, 2014, discloses a low-compression-ratio, ultra-thick, low-temperature resistant hot-rolled H-beam and its production method. The H-beam is composed of the following chemical composition by weight percentage: C: 0.11–0.19%, Si: 0.15–0.30%, Mn: 1.30–1.55%, P≤0.02%, S≤0.008%, Ti: 0.008–0.020%, V: 0.015–0.055%, with the remainder being Fe and unavoidable impurities. The production method of this H-beam includes converter or electric furnace smelting, LF refining, continuous casting of shaped billets under full protection, heating, rolling, and cooling processes. The final product is a low-temperature hot-rolled H-beam with a flange thickness of approximately 35 mm, a compression ratio of 2.5 < 3.0, and good surface quality. Its average longitudinal impact energy at -20℃ is over 150 J, indicating broad market application prospects. The maximum flange thickness of the hot-rolled H-beam produced by this method is 35mm, the minimum compression ratio is 2.5, and the flange thickness is less than 60mm. Therefore, this method is not suitable for the production of extra-thick hot-rolled H-beams with a thickness of more than 60mm and a pressure of 460MPa.

[0011] Therefore, it is essential to provide a low-cost, high-performance 460MPa grade extra-thick hot-rolled H-beam. Summary of the Invention

[0012] The purpose of this invention is to provide a 460MPa grade extra-thick hot-rolled H-beam and its production method. Through composition optimization and matching process parameters, hot-rolled H-beams with flange thicknesses of 60-140mm are obtained, and the yield strength R of the product is [not specified]. eH It has a strength of 466–493 MPa, a tensile strength of 613–680 MPa, an elongation of 22.0–26.5%, and an impact value of 78–106 J at -20℃. It solves the production difficulties of extra-thick, high-strength hot-rolled H-beams, and features low composition and excellent performance.

[0013] The specific technical solution of this invention is as follows:

[0014] A 460MPa grade extra-thick hot-rolled H-beam, comprising the following components by weight percentage:

[0015] C: 0.10–0.20%, Si: 0.30–0.50%, Mn: 0.8%–1.50%, P≤0.015%, S≤0.005%, Nb: 0.010–0.050%, V: 0.040%–0.100%, Ti: 0.006%–0.020%, Cr: 0.10%–0.30%, N: 0.0060%–0.0120%, with the remainder being Fe and unavoidable impurities.

[0016] The composition of the 460MPa grade extra-thick hot-rolled H-beams meets the following requirements: 0.35% ≤ C + Mn / 6 ≤ 0.45%;

[0017] The composition of the 460MPa grade extra-thick hot-rolled H-beams meets the following requirements: 0.060% ≤ Nb + V ≤ 0.130%;

[0018] The above formulas ensure that the steel has sufficient strength and toughness. If the C+Mn / 6 ratio is too low, the carbon equivalent will be too low. A low carbon equivalent weakens the solid solution strengthening effect of C and Mn in the steel, which is detrimental to the strength improvement of the steel and may even make it difficult to guarantee the required strength. If the C+Mn / 6 content is too high, it affects the weldability of the steel, resulting in poor weldability. The recommended C content is 0.10–0.20%, and Mn is 0.8%–1.50%, with 0.35% ≤ C+Mn / 6 ≤ 0.45%. To ensure sufficient strength and good weldability, Nb+V composite addition has a better effect. Adding Nb alone has a good toughness improvement effect, but its strengthening effect is limited. Adding V alone has a good strengthening effect, but its toughness improvement is limited. If the total Nb+V content is too low, the steel will lack strength and toughness. If the total content is too high, especially if the Nb content is too high, the high-temperature plasticity of the steel will decrease significantly, making it prone to cracking defects during production. To ensure sufficient strength and toughness, and to guarantee the surface quality of the steel, Nb: 0.010~0.050%, V: 0.040%~0.100%, and 0.060%≤Nb+V≤0.130%.

[0019] In the calculation formula, the index value of each element = the content of that element in the steel × 100.

[0020] Preferably, the Nb content of the 460MPa grade extra-thick hot-rolled H-beam should be controlled between 0.020% and 0.040%. Nb within this range can prevent the growth of austenite grains during the billet heating process, thereby refining the ferrite grain size and improving the strength and toughness of the steel. Too low an Nb content is detrimental to the steel's strength and toughness, while too high an Nb content is detrimental to its plasticity.

[0021] Preferably, the V content of the 460MPa grade extra-thick hot-rolled H-beam should be controlled between 0.060% and 0.100% to ensure better performance of the post-rolling precipitation strengthening effect. Too low a V content is detrimental to the strength of the steel, while too high a V content is detrimental to the toughness of the steel.

[0022] Preferably, the Ti content of the 460MPa grade extra-thick hot-rolled H-beam should be controlled between 0.008% and 0.015%. Ti is more refractory than Nb and V during the billet heating process, and its ability to inhibit the growth of the original austenite grains is more pronounced. Simultaneously, the fine Ti precipitates after rolling can more significantly pin dislocations, resulting in a higher strengthening effect. Furthermore, Nb precipitates typically precipitate along Ti precipitates, achieving a soft phase encapsulating a hard phase, thereby effectively improving the steel's toughness. Too low a Ti content results in too few Ti precipitates, which is detrimental to strength; too high a Ti content results in excessively large precipitates, which is detrimental to the steel's plasticity and toughness.

[0023] Preferably, the nitrogen (N) content of the 460MPa grade extra-thick hot-rolled H-beam should be controlled between 0.0080% and 0.0100% to ensure the formation of a sufficient amount of fine and uniform carbonitrides with Nb, V, and Ti. Simultaneously, nitrogen can also appropriately improve the hardenability of the steel. If the N content is too low, it will be insufficient to form a sufficient amount of Nb, V, and Ti carbonitrides, making it difficult for the microalloying elements to exert their effects; if the N content is too high, cracks are easily generated.

[0024] Preferably, the Cr content of the 460MPa grade extra-thick hot-rolled H-beam should be controlled between 0.20% and 0.30% to increase the hardenability of the steel after rolling. If the Cr content is too low, it will be detrimental to the strength of the steel, and if the Cr content is too high, it will be detrimental to the plasticity and toughness of the steel.

[0025] The flange microstructure of the 460MPa grade extra-thick hot-rolled H-beam is as follows: the surface 2mm is tempered sorbite; the core is ferrite + pearlite, with ferrite area accounting for 80±2% and pearlite area accounting for 20±2%, and grain size ≥8.0 grade.

[0026] The flange thickness of the 460MPa grade extra-thick hot-rolled H-beam is 60-140mm;

[0027] The yield strength R of the 460MPa grade extra-thick hot-rolled H-beam. eH 466~493MPa, tensile strength 613~680MPa, elongation 22.0~26.5%, impact value at -20℃ is 78~106J.

[0028] This invention provides a method for producing extra-thick hot-rolled H-beams with a strength of 460MPa, comprising: casting billet pulling, stacking and cooling; reheating, controlled rolling and controlled cooling;

[0029] The flange thickness of the cast billet is 180–210 mm.

[0030] The stack cooling, stack cooling time t d >5 hours effectively reduces the hydrogen content in the billet, preventing hydrogen accumulation that could lead to low or even non-existent elongation.

[0031] Preferably, the stack cooling time t d Temperature T of the billet before it enters the cold packing zone d The relationship between them is as follows Temperature T of billet exiting the cold zone c Temperature controlled at 400–500℃, stack cooling time t d The time should be controlled to >5 hours. The temperature T of the billet before it enters the stack cooling zone. d The typical temperature range is 900-1300℃. If the cooling time is too short, it will hinder hydrogen diffusion and negatively impact the tensile properties of the steel. If the cooling time is too long, it will negatively affect production efficiency.

[0032] Stack cooling time t d The unit is hours (h); the temperature T of the billet before it enters the cold packing zone. d The unit is ℃; when calculating with the above formula, simply substitute the data before the unit into the formula.

[0033] The heating process involves feeding the cooled billet into a heating furnace for heating. The heating time is controlled between 120 min and 180 min, and the furnace temperature is controlled between 1200℃ and 1250℃. The furnace exit temperature is 1200℃ to 1250℃.

[0034] Preferably, the heating time should be controlled between 130 min and 150 min. If the heating time is too short, the carbonitrides of Nb, V and Ti cannot be completely melted into austenite. The unmelted second phase particles are prone to be too large when they precipitate after rolling, which does not contribute significantly to the mechanical properties and may even be harmful. If the heating time is too long, the original austenite grain size is prone to grow, which is detrimental to the mechanical properties of the product.

[0035] The heating temperature of this invention should be controlled between 1200℃ and 1250℃. If the heating temperature is too low, the carbonitrides of Nb, V, and Ti cannot be completely melted into austenite. The unmelted second-phase particles are prone to be too large when they precipitate after rolling, which does not contribute significantly to the mechanical properties and may even be harmful. If the heating temperature is too high, the original austenite grain size is prone to grow, which is detrimental to the mechanical properties of the product.

[0036] The controlled rolling and controlled cooling includes a universal rolling stage after the billet opening stage;

[0037] The universal rolling stage: for the first to fourth passes, the flange cooling device should be turned on to control the cooling of the flange. The flange cooling rate is 15℃ / s to 30℃ / s, and the temperature after cooling is controlled at 960℃ to 980℃. Among them, the second pass of universal rolling adopts temperature-controlled rolling, that is, the opening rolling temperature of the web is controlled at 900℃ to 950℃.

[0038] After the universal rolling stage is completed, post-rolling controlled cooling is carried out using a rapid cooling device. The initial cooling temperature is controlled at 900℃~950℃, the flange cooling rate is 30℃ / s~50℃ / s, and the surface temperature of the steel is controlled at 400℃~500℃ after controlled cooling.

[0039] Preferably, the cooling rate of the flanges in the first to fourth passes is controlled at 20℃ / s to 25℃ / s. If the cooling rate is too high, the rolling pressure will be too high and the equipment wear will be too great. If the cooling rate is too low, it will not be conducive to improving the mechanical properties of the steel.

[0040] Preferably, the opening temperature of the second pass of universal rolling should be controlled between 920℃ and 940℃. If the opening temperature is too low, the rolling pressure will be too high, which will cause great damage to the equipment. If the opening temperature is too high, it will not be conducive to grain refinement and will be detrimental to the mechanical properties of the steel.

[0041] Preferably, the starting temperature for controlled cooling is controlled between 910℃ and 930℃. If the starting temperature for controlled cooling is too low, it will be detrimental to both the strength and toughness of the steel. If the starting temperature for controlled cooling is too high, it will be detrimental to the toughness of the steel.

[0042] Preferably, during controlled cooling after rolling, the cooling rate should be controlled at 35℃ / s to 45℃ / s, and the surface temperature of the steel after controlled cooling should be controlled at 430℃ to 460℃. The temperature after controlled cooling is the self-tempering temperature of the extra-thick H-beam. If this temperature is too low, it will be detrimental to the toughness of the steel; if this temperature is too high, it will be detrimental to both the strength and toughness of the steel.

[0043] After controlled rolling and cooling, the product is placed on a cooling bed and cooled naturally. The heat in the core is gradually conducted to the secondary and outer layers, allowing the controlled-cooled secondary and outer layer metals to undergo self-tempering, thereby improving their mechanical properties.

[0044] Compared with existing technologies, the present invention achieves finer and more uniform grain size in the billet through specific composition design during the steelmaking process. After continuous casting, a slow cooling zone is set up to subject the pulled-out stacks of billets to a specific slow cooling process, allowing hydrogen to effectively diffuse out of the billet. A specific controlled rolling and cooling process is employed in the rolling zone. When using the method of the present invention to produce hot-rolled H-beams with flange thicknesses of 60-140mm, the yield strength (ReH) of the product is 466-493MPa, the tensile strength is 613-680MPa, the elongation is 22.0-26.5%, and the impact value at -20℃ is 78-106J. The metallographic structure of the product is as follows: Figure 2 As shown, the surface layer is tempered sorbite; the core is ferrite + pearlite with a grain size of 8.0. The tensile specimen fracture surface has no white spots. Attached Figure Description

[0045] Figure 1This is a schematic diagram of the irregular billet stacking cooling of the present invention; in conventional stacking cooling, the bottom, top and all sides are equipped with windbreak walls with heat insulation cotton, and the billet is naturally and slowly cooled in the stacking cooling zone;

[0046] Figure 2 The present invention is used to produce the metallographic structure of hot-rolled H-beams;

[0047] Figure 3 The fracture surfaces of hot-rolled H-beam tensile specimens are shown in Figure a, where the method of this invention was used, and Figure b, where the method of this invention was not used. Detailed Implementation

[0048] The following description of implementation examples further details the specific embodiments of the present invention:

[0049] Examples 1-5

[0050] An extra-thick hot-rolled H-beam of 460MPa grade comprises the following composition by mass percentage as shown in Table 1. The balance not shown in Table 1 is Fe and unavoidable impurities.

[0051] Comparative Example 1 - Comparative Example 2

[0052] An extra-thick hot-rolled H-beam of 460MPa grade comprises the following composition by mass percentage as shown in Table 1. The balance not shown in Table 1 is Fe and unavoidable impurities.

[0053] Table 1. Composition and content (wt%) of H-beams in each embodiment and comparative example.

[0054]

[0055] The above embodiments and comparative examples are produced according to the following method: including casting billet pulling, stacking and cooling; reheating, controlled rolling and controlled cooling;

[0056] After the billet is drawn, it undergoes stacking cooling for more than 5 hours; preferably, the stacking cooling time t d Temperature T of the billet before it enters the cold packing zone d The relationship between them is as follows Temperature T of billet exiting the cold zone c Temperature controlled at 400–500℃, stack cooling time t d Control time > 5 hours. Temperature T of the billet before it enters the cold packing zone. dThe general temperature range is 900-1300℃. The cooled billet is then fed into a heating furnace. The heating time is controlled between 120 and 180 minutes, and the furnace temperature is controlled between 1200 and 1250℃. The exit temperature is 1200-1250℃. There are no special requirements for the specific process during the billet opening stage. During the universal rolling stage, the flange cooling device should be activated for the first four passes to control the cooling of the flanges at a rate of 15-30℃ / s, with the post-cooling temperature controlled between 960 and 980℃. The second pass of universal rolling uses temperature-controlled rolling, where the opening rolling temperature of the web is controlled between 900 and 950℃. After the universal rolling process is completed, post-rolling controlled cooling should be performed using a rapid cooling device. The opening cooling temperature is controlled between 900 and 950℃, and the cooling rate is 30-50℃ / s. After controlled cooling, the surface temperature of the steel is controlled between 400 and 500℃. Each embodiment and comparative example is controlled according to the parameters in Table 2.

[0057] Table 2. Main process parameters for each embodiment and comparative example.

[0058]

[0059]

[0060] The properties of H-beams produced according to the above method are shown in Table 3. Sampling and sample preparation shall be in accordance with GB / T 2975, tensile testing shall be performed in accordance with GB / T 228.1, and impact testing shall be performed in accordance with GB / T 229.

[0061] Table 3 Main performance of each embodiment and comparative example

[0062]

[0063]

[0064] The underlined data above are data that do not meet the requirements of this invention.

[0065] When hot-rolled H-beams with flange thicknesses of 60-140mm are produced using the method described in this invention, the yield strength (ReH) of the products ranges from 466 to 493 MPa, the tensile strength from 613 to 680 MPa, the elongation from 22.0% to 26.5%, and the impact value at -20℃ from 78 to 106 J, as detailed in Table 1. The metallographic structure of the products is as follows: Figure 2 As shown, its surface layer is tempered sorbite; the core is ferrite + pearlite, with a grain size of 8.0. The tensile specimen fracture surface shows no white spots. Figure 3As shown in (a). Hot-rolled H-beams with a flange thickness of 140mm produced without the method and apparatus described in this invention exhibit yield strength (ReH) of 398–502 MPa, tensile strength of 568–730 MPa, elongation of 20.0–24.5%, and impact value at -20℃ of 22–101 J, as detailed in Table 1. The tensile test specimens of the products show fish-eye-like white spots on the fracture surface, such as… Figure 3 As shown in (b).

Claims

1. A 460MPa grade extra-thick hot-rolled H-beam, characterized in that, The 460MPa grade extra-thick hot-rolled H-beams comprise the following composition by weight percentage: C: 0.10~0.20%, Si: 0.30~0.50%, Mn: 0.8~1.50%, P≤0.015%, S≤0.005%, Nb: 0.010~0.050%, V: 0.040~0.100%, Ti: 0.006~0.020%, Cr: 0.10~0.30%, N: 0.0060~0.0120%, with the remainder being Fe and unavoidable impurities; The composition of the 460MPa grade extra-thick hot-rolled H-beams meets the following requirements: 0.35%≤C+Mn / 6≤0.45%; The composition of the 460MPa grade extra-thick hot-rolled H-beams meets the following requirements: 0.060%≤Nb+V≤0.130%; The flange microstructure of the 460MPa grade extra-thick hot-rolled H-beam is as follows: the surface 2mm is tempered sorbite; the core is ferrite + pearlite, with ferrite accounting for 80±2% of the area and pearlite accounting for 20±2% of the area, and the grain size is ≥8.0 grade; The flange thickness of the 460MPa grade extra-thick hot-rolled H-beam is 60-140mm; The yield strength R of the 460MPa grade extra-thick hot-rolled H-beam. eH 466~493MPa, tensile strength 613~680MPa, elongation 22.0~26.5%, impact value at -20℃ is 78~106J.

2. A method for producing 460MPa grade extra-thick hot-rolled H-beams as described in claim 1, characterized in that, The production method includes casting the billet, pulling it out, cooling it in a pile, reheating it, and then controlling the rolling and cooling process.

3. The production method according to claim 2, characterized in that, The stack cooling, stack cooling time t d >5 hours.

4. The production method according to claim 2, characterized in that, Stack cooling time t d Temperature T of the billet before it enters the cold packing zone d The relationship between them is as follows The temperature T of the billet before it enters the cold packing zone d 900-1300℃.

5. The production method according to claim 2, characterized in that, The reheating process involves sending the cooled billet into a heating furnace for heating. The heating time is controlled between 120 and 180 minutes, and the furnace temperature is controlled between 1200°C and 1250°C. The furnace exit temperature is 1200°C to 1250°C.

6. The production method according to claim 2, characterized in that, The controlled rolling and cooling process involves a universal rolling stage following the billet opening stage.

7. The production method according to claim 6, characterized in that, The universal rolling stage: the flange cooling device is turned on for the first to fourth passes to control the cooling of the flanges at a rate of 15℃ / s to 30℃ / s; the second pass of universal rolling adopts temperature-controlled rolling, and the opening temperature of the web is controlled at 900℃ to 950℃.

8. The production method according to claim 6 or 7, characterized in that, After the rolling process is completed in the universal rolling stage, post-rolling controlled cooling is carried out. A rapid cooling device is used for cooling, with the initial cooling temperature controlled at 900℃~950℃ and the cooling rate at 30℃ / s~50℃ / s. After controlled cooling, the surface temperature of the steel is controlled at 400℃~500℃.

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