High-strength and low-toughness nanoparticle-reinforced heavy H-beams and their preparation methods

Abstract

This invention provides a high-strength, high-toughness, low-content nanoparticle-reinforced heavy H-beam and its preparation method. The preparation method mainly includes: mixing TiAl powder with BN powder and C powder to obtain mixture 1; mixing the liquid flow of mixture 1 with molten aluminum and casting to obtain mixture 2 containing nanoparticles; mixing AlNb powder with B4C powder, drawing, and electro-exploding to obtain mixture 4 containing nanoparticles; mixing mixture 2 and mixture 4, coating to obtain wire; mixing the wire with molten heavy H-beam and then passing it through an argon atmosphere. High-strength and low-content nanoparticle-reinforced heavy H-beams are obtained through protection, refining, vacuum treatment, continuous casting, heat treatment, and rolling. The nanoparticles in the high-strength and low-content nanoparticle-reinforced heavy H-beams account for 0.01-0.03 wt.%, are uniformly dispersed in the heavy H-beams, and have a particle size of 110-270 nm. The flange thickness of the heavy H-beams is ≥100 mm, the impact energy is ≥200 J, the yield strength is ≥460 MPa, the tensile strength is ≥590 MPa, and the elongation is ≥20%.

Description

Technical Field

[0001] This invention belongs to the field of heavy H-beam steel smelting technology, and specifically relates to high-strength and high-toughness, low-content nanoparticle-reinforced heavy H-beam steel and its preparation method. Background Technology

[0002] Heavy-duty H-beams, with their excellent structural strength, flexural modulus, and lightweight design, are widely used in the construction and manufacturing industries. They provide superior support for various building structures and mechanical equipment, ensuring stability and safety through their high strength. The expansion of applications in ultra-high-rise, ultra-large, and high-strength buildings, as well as offshore oil platforms, has increased the demand for large-size, thick-walled heavy-duty hot-rolled H-beams. When the flange thickness of heavy-duty hot-rolled H-beams exceeds 90mm, the flange and web thicknesses are significant, and the cross-sectional shape becomes more complex, making it difficult to simultaneously improve the uniformity and refinement of the microstructure and enhance both strength and toughness. Current technologies primarily address one aspect of high strength or high toughness in heavy-duty H-beams, failing to simultaneously improve strength and toughness while maintaining thick flanges. To address the aforementioned technical challenges, existing technologies primarily rely on adding large amounts of precious metals such as nitrogen (Nb) and rare earth elements to enhance the strength and toughness of heavy hot-rolled H-beams. While this can improve strength and toughness to a certain extent, as the thickness of the flanges and webs of heavy H-beams increases, it becomes difficult to achieve a simultaneous increase in strength and toughness with the addition of large amounts of precious metals. Furthermore, severe segregation occurs; that is, in some applications, strength may meet requirements, but toughness may not, leading to surface cracks in the cast billet, an imbalance between strength and toughness in the steel, and segregation exacerbates the deterioration of steel performance. In addition, current technologies employ a post-rolling online quenching + self-tempering (QST) cooling process, but this process places high demands on cooling equipment and is only suitable for products with thin flanges. In summary, avoiding or reducing the addition of precious metals, simplifying production control processes and reducing equipment replacement costs, while simultaneously being applicable to both thick and thin heavy hot-rolled H-beam flanges, and simultaneously improving the high strength and toughness of heavy H-beams, as well as achieving industrialized production, have become urgent technical challenges that need to be addressed. Summary of the Invention

[0003] To address the aforementioned technical challenges, this invention provides a high-strength, high-toughness, low-content nanoparticle-reinforced heavy H-beam, the preparation method of which includes the following steps: (1) Mix TiAl powder, BN powder and C powder in a mass ratio of 65-75:15-25:5-15 and then mix them at a speed of 20-85 r / min for 13-19 h to obtain mixture 1; then coat mixture 1 with pure aluminum strip to obtain wire A; then treat wire A with high frequency induction to form a liquid flow, and mix the liquid flow with pure aluminum liquid at a mass ratio of 1:17-39 at 650-680℃, and then mix it with mechanical stirring, ultrasonic treatment, casting, rolling and crushing to obtain mixture 2 containing nano-sized TiC and TiB2 particles; The particle size range of the TiAl powder is 0.1-10μm, the particle size range of the BN powder is 25-120μm, and the particle size range of the C powder is 15-55μm. The mass ratio of the mixture 1 to the pure aluminum strip is 3.5-4.0:1; The high-frequency induction processing is as follows: under argon protection, the reaction pressure is 0.01-0.06MPa, the reaction temperature is 3600-4200℃, the power supply operating frequency is 150-250kHz, and the output power is 14-45kW. The mechanical stirring is characterized by a stirring speed of 200-700 r / min and a stirring time of 1-3 min. The ultrasonic treatment is as follows: ultrasonic power 3.5-13kW, ultrasonic frequency 25-40kHz, ultrasonic time 2-6min; The casting and rolling process is as follows: casting and rolling temperature 610-640℃, casting and rolling speed 8-15m / min; (2) After mixing AlNb powder and B4C powder at a mass ratio of 20-50:10-30, the mixture is rotated at 28-68 r / min for 2-13 h to obtain mixture 3; after compacting, sintering, drawing and electro-explosion reaction of mixture 3, mixture 4 containing aluminum-coated nano-sized NbC and NbB2 particles is obtained; mixture 2 and mixture 4 obtained in step (1) are mixed evenly at a mass ratio of 1:2-6, and then coated with stainless steel strip to obtain wire D containing TiC-Nb solid solution and TiB2-Nb solid solution; The particle size range of the B4C powder is 20-300 μm, and the particle size range of the AlNb powder is 10-60 μm. The mass ratio of mixture 2 and mixture 4 to stainless steel is 2.0-4.5:1; The compaction is described as follows: pressure 300-600MPa, holding time 3-7min; The sintering process is as follows: sintering temperature 620-750℃, holding time 1.5-5.5h; The drawing process involves a deformation rate of 9-15% and 10-15 passes. The described electro-explosion reaction is as follows: under argon protection, absolute pressure 0.03-0.07 MPa, voltage 14-26 kV, and current density 10. 5 -10 6 A / mm²; (3) Under the conditions of 1560-1640℃ temperature and argon protection, the wire D obtained in step (2) is mixed with the heavy H-beam melt at a mass ratio of 0.01-0.15%:1, and then refined, vacuum treated, continuously cast, heat treated and rolled to obtain high strength and toughness low content nanoparticle reinforced heavy H-beam. The H-beams, by mass percentage, mainly comprise: C: 0.07-0.12 wt.%; Si: 0.35-0.50 wt.%; Mn: 1.15-1.30 wt.%; P: ≤0.025 wt.%; S: ≤0.01 wt.%; Cr: 0.05-0.30 wt.%; Ni: 0.10-0.30 wt.%; Cu: 0.05-0.30 wt.%; V: 0.07-0.10 wt.%; Mo: ≤0.08 wt.%; Fe: balance; The refining process is described as follows: refining time 16-28 minutes; The vacuum treatment is as follows: working vacuum degree 0.1-10KPa, temperature 1580-1620℃, degassing time 12-36min; The continuous casting process is as follows: liquidus temperature 1520-1530℃, superheat control range 10-25℃, continuous casting speed 0.5-0.7m / min, and total pressure control range of secondary cooling water 9-14MPa. The heat treatment is as follows: holding at 1200-1230℃ for 180-300 minutes; The rolling process is as follows: a total of 7-13 rolling passes, a total reduction of 50-70%, and a reduction of 5-10% per pass, with a rolling temperature ≤950℃. The high-strength, low-toughness, nanoparticle-reinforced heavy H-beams contain nanoparticles, with a nanoparticle mass percentage of 0.01-0.03 wt.%. The nanoparticles are uniformly dispersed in the heavy H-beams, with a particle size of 110-270 nm. The high-strength, low-toughness, nanoparticle-reinforced heavy H-beams have a grain size ≤18 μm, a flange thickness ≥100 mm, an impact energy ≥200 J, a yield strength ≥460 MPa, a tensile strength ≥590 MPa, and an elongation ≥20%.

[0004] Further, in step (1), mixture 1 is obtained by mixing the mixture at a mass ratio of 66-74:16-24:6-14 at a rotation speed of 25-80 r / min for 14-17 h; the mixture 1 is coated with pure aluminum strip to obtain wire A; the wire A is subjected to high-frequency induction treatment to form a liquid flow, and the liquid flow is mixed with pure aluminum liquid at a mass ratio of 1:18-38 at 655-675℃, and then subjected to mechanical stirring, ultrasonic treatment, casting, rolling and crushing to obtain mixture 2 containing nano-sized TiC and TiB2 particles; the particle size range of TiAl powder is 0.2-9 μm, the particle size range of BN powder is 30-110 μm, and the particle size range of C powder is 16-54 μm; the mass ratio of the mixture 1 to the pure aluminum strip is 3.6-3.9:1.

[0005] Further, the high-frequency induction treatment in step (1) is as follows: under argon protection, the reaction pressure is 0.02-0.05MPa, the reaction temperature is 3610-4190℃, the power supply operating frequency is 155-245kHz, and the output power is 15-44kW; the mechanical stirring is as follows: the stirring speed is 220-680r / min, and the stirring time is 1.5-2.5min; the ultrasonic treatment is as follows: the ultrasonic power is 4.5-11kW, the ultrasonic frequency is 26-39kHz, and the ultrasonic time is 2.5-5.5min; the casting and rolling is as follows: the casting and rolling temperature is 615-635℃, and the casting and rolling speed is 9-14m / min.

[0006] Further, in step (2), AlNb powder and B4C powder are mixed at a mass ratio of 21-49:12-28 and subjected to a rotation speed of 30-66 r / min for 3-12 h to obtain mixture 3; mixture 3 is then compacted, sintered, drawn, and subjected to an electro-explosion reaction to obtain mixture 4 containing aluminum-coated nano-sized NbC and NbB2 particles; mixture 2 and mixture 4 obtained in step (1) are mixed evenly at a mass ratio of 1:3-5, and then coated with stainless steel strip to obtain wire D containing TiC-Nb solid solution and TiB2-Nb solid solution; the particle size range of B4C powder is 25-295 μm, and the particle size range of AlNb powder is 15-55 μm; the mass ratio of mixture 2 and mixture 4 to stainless steel is 2.1-4.4:1.

[0007] Further, the compaction in step (2) is as follows: pressure 350-550 MPa, holding time 4-6 min; the sintering is as follows: sintering temperature 630-730℃, holding time 2-5 h; the drawing is as follows: deformation 10-14%, 11-14 passes; the electro-explosion reaction is as follows: under argon protection, absolute pressure 0.04-0.06 MPa, voltage 15-24 kV, current density 10 5 -10 6 A / mm².

[0008] Further, the chemical composition of the H-beam steel described in step (3) by mass percentage is as follows: C: 0.075-0.115wt.%; Si: 0.40-0.45wt.%; Mn: 1.20-1.25wt.%; P: ≤0.020wt.%; S: ≤0.009wt.%; Cr: 0.10-0.25wt.%; Ni: 0.15-0.25wt.%; Cu: 0.10-0.25wt.%; V: 0.08-0.09wt.%; Mo: ≤0.07wt.%; Fe: balance.

[0009] Further, the refining in step (3) is as follows: refining time 17-27 min; vacuum treatment is as follows: working vacuum degree 0.2-9.9 KPa, temperature 1582-1618℃, degassing time 13-35 min; continuous casting is as follows: liquidus temperature 1521-1529℃, superheat control range 11-24℃, continuous casting speed 0.55-0.65 m / min, secondary cooling water total pressure control range 10-13 MPa; heat treatment is as follows: holding at 1205-1225℃ for 182-298 min; rolling is as follows: total rolling passes 8-12, total reduction 52-68%, rolling per pass is as follows: reduction per pass 6-9%, rolling temperature ≤940℃.

[0010] Furthermore, according to claim 1, the high-strength, low-toughness, low-content nanoparticle-reinforced heavy H-beam is characterized in that the grain size of the high-strength, low-toughness, low-content nanoparticle-reinforced heavy H-beam is 8-17μm, the flange thickness is 110-160mm, the impact energy is 210-280J, the yield strength is 465-540MPa, the tensile strength is 595-650MPa, and the elongation is 21-28%.

[0011] Compared with existing technologies, the present invention has the following advantages:

[0012] 1. Hot-rolled heavy H-beams, due to their complex cross-sectional shape and large flange thickness, suffer from poor microstructure uniformity. Existing technologies mainly improve the performance of heavy H-beams by adding alloying elements such as rare earth elements and nitrogen (Nb). However, this faces the contradiction of balancing alloy addition amount with cost control and difficulty in simultaneously improving strength and toughness. Furthermore, with increased flange thickness, alloying elements are prone to compositional segregation in heavy H-beams, resulting in insufficient strength and toughness in localized areas. Therefore, it is difficult to simultaneously improve the flange thickness and strength and toughness of heavy H-beams. Existing alloying elements add Nb at a rate of 0.06-0.15 wt.% and rare earth elements at a rate of 0.05-0.12 wt.%, resulting in a microstructure mainly composed of ferrite and pearlite with a size greater than 30 μm. This invention, however, adds a low content of nanoparticles, controlling the nanoparticle content to 0.03%. The percentage is below 100%, and through the interaction, ratio, process, and control of process parameters between nanoparticles and elements, without adding large amounts of high-cost metal elements such as rare earth and Nb, the process is simplified, avoiding the coarse microstructure (reaching the hundred-micrometer level) caused by existing technologies when the flange thickness is greater than 100mm. The present invention obtains finer ferrite, bainite, and pearlite when the flange thickness is greater than 100mm, with a grain size ≤18μm. At the same time, the yield strength of existing heavy H-beams is ≤420MPa and the impact energy is ≤150J, while the present invention obtains a yield strength ≥460MPa and an impact energy ≥200J for heavy H-beams. Compared with existing technologies, it achieves simultaneous improvement in strength, toughness, and thickness, without the need for other auxiliary processes, and is simple to operate and easy to industrialize.

[0013] 2. This invention adds a small amount of raw materials, reducing the use of a large number of high-cost elements, such as Nb and rare earth elements. In the original composition design, only ≤0.03wt.% of nanoparticles are added. The nanoparticles do not contain high-cost metal elements and have no requirements for production equipment, resulting in low production costs. At the same time, it simplifies the production process, improves production efficiency, and increases the added value of the product.

[0014] 3. Compared with the existing technology, it is difficult to achieve simultaneous improvement of the thickness and high strength and toughness of heavy H-beams. However, the present invention can simultaneously improve the thickness and high strength and toughness of heavy H-beams. The flange thickness of the heavy H-beams of the present invention can reach ≥100mm, impact energy ≥200J, yield strength ≥460MPa, tensile strength ≥590MPa, elongation ≥20%, and simultaneously improve the alloy strength and toughness. Attached Figure Description

[0015] Figure 1 This is a room temperature tensile curve of the high-strength and low-toughness nanoparticle-reinforced heavy H-beam 1 in Example 1 of the present invention.

[0016] Figure 2 This is a room temperature tensile curve of the high-strength and low-toughness nanoparticle-reinforced heavy H-beam 2 in Example 2 of the present invention.

[0017] Figure 3 This is a room temperature tensile curve of the high-strength and low-toughness nanoparticle-reinforced heavy H-beam 3 in Example 3 of the present invention.

[0018] Figure 4 This is a room temperature tensile curve of heavy H-beam 4 in Comparative Example 1 of the present invention. Detailed Implementation

[0019] The present invention will be further illustrated by specific embodiments below. These embodiments are for illustrative purposes only, and the scope of protection of the present invention is not limited to these embodiments. Example 1

[0020] The preparation method of high-strength, low-toughness, nanoparticle-reinforced heavy H-beam 1 includes the following steps: (1) TiAl powder, BN powder and C powder are mixed at a mass ratio of 67:18:7 and rotated at 25 r / min for 14 h to obtain mixture 1; mixture 1 is coated with pure aluminum strip to obtain wire A; wire A is treated with high frequency induction to form liquid flow, and the liquid flow is mixed with pure aluminum liquid at a mass ratio of 1:19 at 665℃, and then mixed with mechanical stirring, ultrasonic treatment, casting, rolling and crushing to obtain mixture 2 containing nano-sized TiC and TiB2 particles; The particle size range of the TiAl powder is 0.1-10μm, the particle size range of the BN powder is 25-120μm, and the particle size range of the C powder is 15-55μm. The mass ratio of the mixture 1 to the pure aluminum strip is 3.8:1; The high-frequency induction processing is carried out under argon protection, with a reaction pressure of 0.02 MPa, a reaction temperature of 3800℃, a power supply operating frequency of 160 kHz, and an output power of 15 kW. The mechanical stirring is performed at a speed of 320 r / min for a duration of 1.5 min. The ultrasonic treatment was performed with an ultrasonic power of 4.5 kW, an ultrasonic frequency of 26 kHz, and an ultrasonic time of 2.5 min. The casting and rolling process is as follows: casting and rolling temperature 615℃, casting and rolling speed 9m / min; (2) AlNb powder and B4C powder were mixed at a mass ratio of 21:12 and subjected to a rotation speed of 32 r / min for 3 h to obtain mixture 3; mixture 3 was compacted, sintered, drawn and subjected to an electro-explosion reaction to obtain mixture 4 containing aluminum-encapsulated nano-sized NbC and NbB2 particles; mixture 2 and mixture 4 obtained in step (1) were mixed evenly at a mass ratio of 1:3, and then coated with stainless steel strip to obtain wire D containing TiC-Nb solid solution and TiB2-Nb solid solution; The particle size range of the B4C powder is 20-300 μm, and the particle size range of the AlNb powder is 10-60 μm. The mass ratio of mixture 2 and mixture 4 to stainless steel is 3:1; The compaction is as follows: pressure 350 MPa, holding time 4 min; The sintering process is as follows: sintering temperature 620℃, holding time 2h; The drawing process is as follows: 10% deformation, 11 passes; The described electro-explosion reaction is as follows: under argon protection, absolute pressure 0.04 MPa, voltage 16 kV, and current density 10... 5 A / mm²; (3) Under the conditions of 1565℃ temperature and argon protection, the wire D obtained in step (2) is mixed with the heavy H-beam melt at a mass ratio of 0.01%:1, and then refined, vacuum treated, continuously cast, heat treated and rolled to obtain high strength and toughness low content nanoparticle reinforced heavy H-beam 1. The H-beams, by weight percentage, mainly comprise: C: 0.11 wt.%; Si: 0.42 wt.%; Mn: 1.23 wt.%; P: 0.009 wt.%; S: 0.003 wt.%; Cr: 0.14 wt.%; Ni: 0.16 wt.%; Cu: 0.14 wt.%; V: 0.088 wt.%; Mo: 0.056 wt.%; Fe: balance; The refining process is described as follows: refining time 18 minutes; The vacuum treatment is as follows: working vacuum degree 5 kPa, temperature 1590℃, degassing time 16 min; The continuous casting is characterized by a liquidus temperature of 1525℃, a superheat control range of 15℃, a continuous casting speed of 0.6m / min, and a total pressure control range of 11MPa for the secondary cooling water. The heat treatment is as follows: holding at 1210℃ for 190 minutes; The rolling process is as follows: a total of 8 rolling passes, a total reduction of 55%, and a reduction of 6% per pass, with a rolling temperature of 940℃. The room temperature tensile curve of the high-strength, low-toughness nanoparticle-reinforced heavy H-beam 1 prepared in this embodiment is shown in the figure below. Figure 1As shown, its yield strength is 470 MPa, tensile strength is 598 MPa, and fracture strain is 22%; as shown in Table 1, the impact energy is 226 J; the flange thickness of the high-strength and low-content nanoparticle-reinforced heavy H-beam 1 prepared in this embodiment is 137 mm, in which the nanoparticles account for 0.01% of the mass of the heavy H-beam, the particle size is 145-250 nm, the microstructure is fine ferrite, bainite, and pearlite, and the grain size is 13-16 μm. While improving strength, toughness is also improved, and the existing production equipment is not changed, making it suitable for industrial production and product promotion. Example 2

[0021] The preparation method of high-strength, low-toughness, nanoparticle-reinforced heavy H-beam 2 includes the following steps: (1) TiAl powder, BN powder and C powder are mixed at a mass ratio of 71:23:11 and rotated at 45 r / min for 16 h to obtain mixture 1; mixture 1 is coated with pure aluminum strip to obtain wire A; wire A is treated with high frequency induction to form a liquid flow, and the liquid flow is mixed with pure aluminum liquid at a mass ratio of 1:23 at 670℃. After mechanical stirring, ultrasonic treatment, casting, rolling and crushing, mixture 2 containing nano-sized TiC and TiB2 particles is obtained. The particle size range of the TiAl powder is 0.1-10μm, the particle size range of the BN powder is 25-120μm, and the particle size range of the C powder is 15-55μm. The mass ratio of the mixture 1 to the pure aluminum strip is 3.7:1; The high-frequency induction processing is carried out under argon protection, with a reaction pressure of 0.04 MPa, a reaction temperature of 4000℃, a power supply operating frequency of 180 kHz, and an output power of 20 kW. The mechanical stirring is performed at a speed of 340 r / min for a duration of 2 min. The ultrasonic treatment was performed with an ultrasonic power of 6.5 kW, an ultrasonic frequency of 28 kHz, and an ultrasonic time of 3 min. The casting and rolling process is as follows: casting and rolling temperature 625℃, casting and rolling speed 10m / min; (2) AlNb powder and B4C powder were mixed at a mass ratio of 23:13 and subjected to a rotation speed of 35 r / min for 6 h to obtain mixture 3; mixture 3 was compacted, sintered, drawn and subjected to an electro-explosion reaction to obtain mixture 4 containing aluminum-coated nano-sized NbC and NbB2 particles; mixture 2 and mixture 4 obtained in step (1) were mixed evenly at a mass ratio of 1:4, and then coated with stainless steel strip to obtain wire D containing TiC-Nb solid solution and TiB2-Nb solid solution; The particle size range of the B4C powder is 20-300 μm, and the particle size range of the AlNb powder is 10-60 μm. The mass ratio of mixture 2 and mixture 4 to stainless steel is 4:1; The compaction is defined as follows: pressure 360 ​​MPa, holding time 5 min; The sintering process is as follows: sintering temperature 650℃, holding time 3h; The drawing process is as follows: 12% deformation, 12 passes; The described electro-explosion reaction is as follows: under argon protection, absolute pressure 0.05 MPa, voltage 20 kV, and current density 10... 5 A / mm²; (3) Under the conditions of 1570℃ temperature and argon protection, the wire D obtained in step (2) is mixed with the heavy H-beam melt at a mass ratio of 0.02%:1, and then refined, vacuum treated, continuously cast, heat treated and rolled to obtain high strength and toughness low content nanoparticle reinforced heavy H-beam 2. The H-beams, by weight percentage, mainly comprise: C: 0.10 wt.%; Si: 0.41 wt.%; Mn: 1.24 wt.%; P: 0.008 wt.%; S: 0.004 wt.%; Cr: 0.15 wt.%; Ni: 0.12 wt.%; Cu: 0.13 wt.%; V: 0.085 wt.%; Mo: 0.054 wt.%; Fe: balance; The refining process is described as follows: refining time 20 minutes; The vacuum treatment is as follows: working vacuum degree 10 kPa, temperature 1600℃, degassing time 20 min; The continuous casting is characterized by a liquidus temperature of 1526℃, a superheat control range of 20℃, a continuous casting speed of 0.55m / min, and a total secondary cooling water pressure control range of 9.5 MPa. The heat treatment is as follows: holding at 1220℃ for 200 min; The rolling process is as follows: a total of 10 rolling passes, a total reduction of 60%, and a rolling reduction of 8% per pass at a rolling temperature of 935°C. The room temperature tensile curve of the high-strength, low-toughness nanoparticle-reinforced heavy H-beam 2 prepared in this embodiment is shown in the figure below. Figure 2As shown, its yield strength is 472 MPa, tensile strength is 609 MPa, and fracture strain is 21%; as shown in Table 1, the impact energy is 232 J; the flange thickness of the high-strength and low-content nanoparticle-reinforced heavy H-beam 2 prepared in this embodiment is 137 mm, in which the nanoparticles account for 0.02% of the mass of the heavy H-beam, the particle size is 130-235 nm, the microstructure is fine ferrite, bainite, and pearlite, and the grain size is 12-17 μm. While improving strength, toughness is also improved, and the existing production equipment is not changed, making it suitable for industrial production and product promotion. Example 3

[0022] The preparation method of high-strength, low-toughness, nanoparticle-reinforced heavy H-beam 3 includes the following steps: (1) TiAl powder, BN powder and C powder are mixed at a mass ratio of 69:20:9 and rotated at 30 r / min for 18 h to obtain mixture 1; mixture 1 is coated with pure aluminum strip to obtain wire A; wire A is treated with high frequency induction to form liquid flow, and the liquid flow is mixed with pure aluminum liquid at a mass ratio of 1:20 at 675℃. After mechanical stirring, ultrasonic treatment, casting, rolling and crushing, mixture 2 containing nano-sized TiC and TiB2 particles is obtained. The particle size range of the TiAl powder is 0.1-10μm, the particle size range of the BN powder is 25-120μm, and the particle size range of the C powder is 15-55μm. The mass ratio of the mixture 1 to the pure aluminum strip is 3.6:1; The high-frequency induction processing is carried out under argon protection, with a reaction pressure of 0.06 MPa, a reaction temperature of 4100℃, a power supply operating frequency of 200 kHz, and an output power of 30 kW. The mechanical stirring is performed at a speed of 345 r / min for a duration of 2.5 min. The ultrasonic treatment was performed with an ultrasonic power of 8.5 kW, an ultrasonic frequency of 30 kHz, and an ultrasonic time of 3.5 min. The casting and rolling process is as follows: casting and rolling temperature 630℃, casting and rolling speed 12m / min; (2) AlNb powder and B4C powder were mixed at a mass ratio of 24:15 and subjected to a rotation speed of 40 r / min for 9 h to obtain mixture 3; mixture 3 was compacted, sintered, drawn, and subjected to an electro-explosion reaction to obtain mixture 4 containing aluminum-encapsulated nano-sized NbC and NbB2 particles; mixture 2 and mixture 4 obtained in step (1) were mixed evenly at a mass ratio of 1:5, and then coated with stainless steel strip to obtain wire D containing TiC-Nb solid solution and TiB2-Nb solid solution; The particle size range of the B4C powder is 20-300 μm, and the particle size range of the AlNb powder is 10-60 μm. The mass ratio of mixture 2 and mixture 4 to stainless steel is 4:1; The compaction is as follows: pressure 370 MPa, holding time 6 min; The sintering process is as follows: sintering temperature 660℃, holding time 4h; The drawing process is as follows: 13% deformation, 14 passes; The described electro-explosion reaction is as follows: under argon protection, absolute pressure 0.06 MPa, voltage 24 kV, and current density 10. 5 A / mm²; (3) Under the conditions of 1580℃ temperature and argon protection, the wire D obtained in step (2) is mixed with the heavy H-beam melt at a mass ratio of 0.03%:1, and then refined, vacuum treated, continuously cast, heat treated and rolled to obtain high strength and toughness low content nanoparticle reinforced heavy H-beam 3. The H-beams, by weight percentage, mainly comprise: C: 0.12 wt.%; Si: 0.41 wt.%; Mn: 1.20 wt.%; P: 0.007 wt.%; S: 0.003 wt.%; Cr: 0.16 wt.%; Ni: 0.15 wt.%; Cu: 0.16 wt.%; V: 0.084 wt.%; Mo: 0.058 wt.%; Fe: balance; The refining process is described as follows: refining time 22 minutes; The vacuum treatment is as follows: working vacuum degree 6 kPa, temperature 1585℃, degassing time 24 min; The continuous casting is characterized by a liquidus temperature of 1524℃, a superheat control range of 14℃, a continuous casting speed of 0.65m / min, and a total pressure control range of 10MPa for the secondary cooling water. The heat treatment is as follows: holding at 1225℃ for 220 minutes; The rolling process is as follows: a total of 12 rolling passes, a total reduction of 65%, and a rolling reduction of 10% per pass at a rolling temperature of 930°C. The room temperature tensile curve of the high-strength, low-toughness nanoparticle-reinforced heavy H-beam 3 prepared in this embodiment is shown in the figure below. Figure 3 As shown, its yield strength is 485 MPa, tensile strength is 611 MPa, and fracture strain is 24%; as shown in Table 1, the impact energy is 240 J; the flange thickness of the high-strength and low-content nanoparticle-reinforced heavy H-beam 3 prepared in this embodiment is 137 mm, in which the nanoparticles account for 0.03% of the mass of the heavy H-beam, the particle size is 115-220 nm, the microstructure is fine ferrite, bainite, and pearlite, and the grain size is 8-11 μm. While improving strength, toughness is also improved, and the existing production equipment is not changed, making it suitable for industrial production and product promotion. Comparative Example 1

[0023] Heavy H-beam 4, its preparation method includes the following steps: (1) Under the conditions of 1580℃ temperature and argon protection, heavy H-beam steel melt is refined, vacuum treated, continuously cast, heat treated and rolled to obtain heavy H-beam steel 4; The chemical composition of the H-beam steel, by mass percentage, is as follows: C: 0.10 wt.%; Si: 0.39 wt.%; Mn: 1.21 wt.%; P: 0.009 wt.%; S: 0.004 wt.%; Cr: 0.14 wt.%; Ni: 0.16 wt.%; Cu: 0.13 wt.%; V: 0.084 wt.%; Mo: 0.061 wt.%; Fe: balance; The refining process is described as follows: refining time 18 minutes; The vacuum treatment is as follows: working vacuum degree 5 kPa, temperature 1590℃, degassing time 16 min; The continuous casting is characterized by a liquidus temperature of 1525℃, a superheat control range of 15℃, a continuous casting speed of 0.6m / min, and a total pressure control range of 11MPa for the secondary cooling water. The heat treatment is as follows: holding at 1210℃ for 190 minutes; The rolling process is as follows: a total of 8 rolling passes, a total reduction of 55%, and a reduction of 6% per pass, with a rolling temperature of 940℃. The room temperature tensile curve of heavy H-beam 4 in this comparative example is shown below. Figure 4 As shown, its yield strength is 454 MPa, tensile strength is 590 MPa, and fracture strain is 18%; as shown in Table 1, the impact energy is 191 J; the flange thickness of heavy H-beam 4 is 137 mm, and the microstructure is relatively coarse ferrite, bainite, and pearlite, with a grain size of 20-28 μm.

[0024] The main difference between Examples 1-3 and Comparative Example 1 is that different contents (0.01 wt.%, 0.02 wt.%, 0.03 wt.%) of nanoparticles were added in Examples 1-3; no nanoparticles were added in Comparative Example 1, and the process parameters were the same as in Example 1. As shown in Table 1, compared with Comparative Example 1, the yield strength, tensile strength, fracture strain, and impact energy of the high-strength, low-toughness nanoparticle-reinforced heavy H-beam 1 of Example 1 increased by 3.52%, 1.35%, 22.22%, and 18.32%, respectively; compared with Comparative Example 1, the yield strength, tensile strength, fracture strain, and impact energy of the high-strength, low-toughness nanoparticle-reinforced heavy H-beam 2 of Example 2 increased by 3.96%, 3.22%, 16.67%, and 21.47%, respectively; and compared with Comparative Example 1, the yield strength, tensile strength, fracture strain, and impact energy of the high-strength, low-toughness nanoparticle-reinforced heavy H-beam 3 of Example 3 increased by 6.83%, 3.56%, and 33.33%, respectively. %, 25.65%; therefore, compared with Comparative Example 1, the high-strength and tough, low-content nanoparticle-reinforced heavy H-beams obtained in Examples 1-3 of the present invention have better strength and toughness properties. Comparative Example 2

[0025] Patent document CN108754327B discloses a high-toughness weather-resistant hot-rolled H-beam for bridge structures with a yield strength of 460MPa and its production method. The production method includes the following steps: hot metal pretreatment, converter smelting, argon blowing refining, LF refining, special-shaped billet protective continuous casting, H-beam rolling, and air cooling after rolling. The typical H-beam steel has the following chemical composition by mass percentage: C: 0.10 wt.%; Si: 0.38 wt.%; Mn: 1.49 wt.%; P: 0.013 wt.%; S: 0.004 wt.%; Cr: 0.58 wt.%; Ni: 0.35 wt.%; Cu: 0.32 wt.%; V: 0.091 wt.%; Nb: 0.022 wt.%; Alt: 0.023 wt.%; Fe: balance; as shown in Table 1, the H-beam steel has a flange thickness of 31.8 mm, a yield strength of 468 MPa, a tensile strength of 579 MPa, an elongation after fracture of 24%, and an impact energy of 161 J. Comparative Example 2 obtained a heavy H-beam with a flange thickness of 31.8 mm by adding 0.022 wt.% Nb and 0.58 wt.% Cr along with other alloying elements and air cooling after rolling. Its microstructure consists of ferrite, bainite and pearlite, with a grain size of 17-19 μm.

[0026] Compared to Comparative Example 2, taking Example 1, which has the worst performance in this invention, as an example, this invention does not add the precious metal element Nb, and the Cr content is 0.14 wt.% and the Ni content is 0.16 wt.%, while Comparative Example 2 adds 0.022 wt.% Nb, the Cr content is 0.58 wt.%, and the Ni content is 0.35 wt.%. Therefore, the amount of alloying elements such as Cr and Ni added in Comparative Example 2 is higher than that in Example 1. Compared with Comparative Example 2, this invention significantly reduces the raw material cost. The rolling process of Example 1 involves a total of 8 rolling passes, a total reduction of 55%, a reduction of 6% per pass, and a rolling temperature of 940°C. In Comparative Example 2, the cumulative reduction in the flange thickness direction of the first 3 reciprocating rolling passes is 35%, the rolling temperature is 948°C, and the temperature after the 3rd pass is controlled at 897°C. The rolling process strictly controls the reduction distribution and temperature, thus simplifying the rolling process of this invention. Example 1 yielded a heavy H-beam with a flange thickness of 137 mm, exhibiting a yield strength of 470 MPa, a tensile strength of 598 MPa, a fracture strain of 22%, and an impact energy of 226 J. Comparative Example 2 yielded a heavy H-beam with a flange thickness of 31.8 mm, exhibiting a yield strength of 468 MPa, a tensile strength of 579 MPa, an elongation after fracture of 24%, and an impact energy of 161 J. Compared to existing technologies, this invention achieves simultaneous improvement in flange thickness and toughness. Example 1 of this invention adds 0.01 wt.% nanoparticles to the molten heavy H-beam. The nanoparticles are uniformly dispersed, with a grain size of 13-16 μm, while the heavy H-beam in Comparative Example 2 has a grain size of 17-19 μm, achieving a refined microstructure. Therefore, this invention, without altering existing production processes and equipment, eliminates the need for large-scale addition of precious metal elements, reduces raw material costs, and simplifies the process, enabling the production of heavy H-beams with flange thicknesses greater than 100 mm while simultaneously improving the strength and toughness of the H-beam.

[0027] Table 1: Mechanical property results of heavy H-beams in each embodiment and comparative example

[0028] In summary, compared with the prior art, the advantages of this invention are: no precious metal alloying elements such as Nb and rare earth are added, and the addition of a large number of alloying elements is reduced, thereby reducing raw material costs. At the same time, it avoids the performance inconsistencies caused by segregation and uneven microstructure due to high alloying; it avoids complex rolling processes, simplifies the process flow, and reduces energy consumption. Existing technologies struggle to simultaneously improve the strength or toughness of heavy H-beams. While increasing the strength of heavy H-beams with thick flanges often results in reduced toughness and coarse microstructure, limiting the ability to refine grains through subsequent processing. For instance, existing technologies achieve grain refinement by adding alloying elements and controlling the rolling process; however, increasing the cross-sectional size requires adding large amounts of alloying elements and complex rolling processes, increasing the production cost of heavy H-beams. In contrast, this invention produces heavy H-beams with superior performance even when the flange thickness exceeds 100mm. This invention uses low-content nanoparticles, with the mass controlled below 0.03%, reducing the amount of alloying elements added, lowering raw material costs, and simplifying the production process without altering existing equipment. This achieves high thickness and refined grains in heavy H-beams, simultaneously improving both strength and toughness. Furthermore, the uniformly dispersed nanoparticles in this invention maintain a clean interface with the heavy H-beams, promoting homogenization of their performance. Furthermore, each embodiment of this invention uses different component ratios and process parameters, yet achieves significantly different technical effects. This demonstrates that the optimal effect of this invention is not determined by a single component, ratio, process, or parameter, but rather by the synergistic control of alloying element interactions, ratios, processes, and process parameters. Moreover, only within the scope of the claims of this invention can a significantly improved technical effect be achieved. This invention overcomes the technical bottleneck of existing technologies, which primarily prepare conventional H-beams, making it difficult to simultaneously improve the strength and toughness of large-flange-thickness H-beams. This invention improves the instability of the material's mechanical properties and processing characteristics, ultimately enabling the heavy H-beams prepared by this invention to possess stable and reliable comprehensive performance in actual service. Specifically, in the high-strength, low-toughness, low-content nanoparticle-reinforced heavy H-beams of this invention, the nanoparticles are uniformly dispersed within the heavy H-beams, with a particle size of 110-270 nm, a grain size ≤18 μm, a flange thickness ≥100 mm, an impact energy ≥200 J, a yield strength ≥460 MPa, a tensile strength ≥590 MPa, and an elongation ≥20%.

Claims

1. A high-toughness, low-content nanoparticle- strengthened heavy H-beam characterized in that, Its preparation method includes the following steps: (1) Mix TiAl powder, BN powder and C powder in a mass ratio of 65-75:15-25:5-15 and then rotate at a speed of 20-85 r / min for 13-19 h to obtain mixture 1; then coat mixture 1 with pure aluminum strip to obtain wire A; After high-frequency induction treatment, wire A is formed into a liquid flow. The liquid flow is mixed with pure aluminum liquid at a mass ratio of 1:17-39 at 650-680℃. After mechanical stirring, ultrasonic treatment, casting, rolling and crushing, a mixture 2 containing nano-sized TiC and TiB2 particles is obtained. The particle size range of the TiAl powder is 0.1-10 μm, the particle size range of the BN powder is 25-120 μm, and the particle size range of the C powder is 15-55 μm. The mass ratio of the mixture 1 to the pure aluminum strip is 3.5-4.0:1; The high-frequency induction processing is as follows: under argon protection, the reaction pressure is 0.01-0.06MPa, the reaction temperature is 3600-4200℃, the power supply operating frequency is 150-250kHz, and the output power is 14-45kW. The mechanical stirring is characterized by a stirring speed of 200-700 r / min and a stirring time of 1-3 min. The ultrasonic treatment is as follows: ultrasonic power 3.5-13kW, ultrasonic frequency 25-40kHz, ultrasonic time 2-6min; The casting and rolling process is as follows: casting and rolling temperature 610-640℃, casting and rolling speed 8-15m / min; (2) After mixing AlNb powder and B4C powder at a mass ratio of 20-50:10-30, the mixture is rotated at 28-68 r / min for 2-13 h to obtain mixture 3; after compacting, sintering, drawing and electro-explosion reaction of mixture 3, mixture 4 containing aluminum-coated nano-sized NbC and NbB2 particles is obtained; mixture 2 and mixture 4 obtained in step (1) are mixed evenly at a mass ratio of 1:2-6, and then coated with stainless steel strip to obtain wire D containing TiC-Nb solid solution and TiB2-Nb solid solution; The particle size range of the B4C powder is 20-300 μm, and the particle size range of the AlNb powder is 10-60 μm. The mass ratio of mixture 2 and mixture 4 to stainless steel is 2.0-4.5:1; The compaction is described as follows: pressure 300-600MPa, holding time 3-7min; The sintering process is as follows: sintering temperature 620-750℃, holding time 1.5-5.5h; The drawing process involves a deformation rate of 9-15% and 10-15 passes. The electric explosion reaction is: under the protection of argon, absolute pressure 0.03-0.07 MPa, voltage 14-26 kV, current density 10 5 - 10 6 A / mm²; (3) Under the conditions of 1560-1640℃ temperature and argon protection, the wire D obtained in step (2) is mixed with the heavy H-beam melt at a mass ratio of 0.01-0.15%:1, and then refined, vacuum treated, continuously cast, heat treated and rolled to obtain high strength and toughness low content nanoparticle reinforced heavy H-beam. The H-beams, by mass percentage, mainly consist of: C: 0.07-0.12 wt.%; Si: 0.35-0.50 wt.%; Mn: 1.15-1.30 wt.%; P: ≤0.025 wt.%; S: ≤0.01 wt.%; Cr: 0.05-0.30 wt.%; Ni: 0.10-0.30 wt.%; Cu: 0.05-0.30 wt.%; V: 0.07-0.10 wt.%; Mo: ≤0.08 wt.%; Fe: Balance; The refining process is described as follows: refining time 16-28 minutes; The vacuum treatment is as follows: working vacuum degree 0.1-10KPa, temperature 1580-1620℃, degassing time 12-36min; The continuous casting process is as follows: liquidus temperature 1520-1530℃, superheat control range 10-25℃, continuous casting speed 0.5-0.7m / min, and total pressure control range of secondary cooling water 9-14MPa. The heat treatment is as follows: holding at 1200-1230℃ for 180-300 minutes; The rolling process is as follows: a total of 7-13 rolling passes, a total reduction of 50-70%, and a reduction of 5-10% per pass, with a rolling temperature ≤950℃. The high-strength, low-toughness, nanoparticle-reinforced heavy H-beams contain nanoparticles, with a nanoparticle mass percentage of 0.01-0.03 wt.%. The nanoparticles are uniformly dispersed in the heavy H-beams, with a particle size of 110-270 nm. The high-strength, low-toughness, nanoparticle-reinforced heavy H-beams have a grain size ≤18 μm, a flange thickness ≥100 mm, an impact energy ≥200 J, a yield strength ≥460 MPa, a tensile strength ≥590 MPa, and an elongation ≥20%.

2. The high tough low content nanoparticle reinforced heavy gauge H-beam steel of claim 1, wherein, In step (1), mixture 1 is obtained by rotating at a speed of 25-80 r / min for 14-17 h at a mass ratio of 66-74:16-24:6-14. Mixture 1 is then coated with pure aluminum strip to obtain wire A. Wire A is then subjected to high-frequency induction treatment to form a liquid flow. The liquid flow is mixed with pure aluminum liquid at a mass ratio of 1:18-38 at 655-675℃. After mechanical stirring, ultrasonic treatment, casting, rolling, and crushing, mixture 2 containing nano-sized TiC and TiB2 particles is obtained. The particle size range of TiAl powder is 0.2-9 μm, the particle size range of BN powder is 30-110 μm, and the particle size range of C powder is 16-54 μm. The mass ratio of mixture 1 to pure aluminum strip is 3.6-3.9:

1.

3. The high tough low content nanoparticle reinforced heavy gauge H-beam steel of claim 1, wherein, The high-frequency induction treatment in step (1) is as follows: under argon protection, the reaction pressure is 0.02-0.05MPa, the reaction temperature is 3610-4190℃, the power supply operating frequency is 155-245kHz, and the output power is 15-44kW; the mechanical stirring is as follows: the stirring speed is 220-680r / min, and the stirring time is 1.5-2.5min; the ultrasonic treatment is as follows: the ultrasonic power is 4.5-11kW, the ultrasonic frequency is 26-39kHz, and the ultrasonic time is 2.5-5.5min; the casting and rolling is as follows: the casting and rolling temperature is 615-635℃, and the casting and rolling speed is 9-14m / min.

4. The high-strength, low-toughness, nanoparticle-reinforced heavy H-beam according to claim 1, characterized in that, In step (2), AlNb powder and B4C powder are mixed at a mass ratio of 21-49:12-28 and subjected to a rotation speed of 30-66 r / min for 3-12 h to obtain mixture 3. After compaction, sintering, drawing, and electro-explosion reaction, mixture 3 is subjected to a mixture 4 containing aluminum-encapsulated nano-sized NbC and NbB2 particles. Mix mixture 2 and mixture 4 obtained in step (1) are mixed evenly at a mass ratio of 1:3-5, and then coated with stainless steel strip to obtain wire D containing TiC-Nb solid solution and TiB2-Nb solid solution. The particle size range of B4C powder is 25-295 μm, and the particle size range of AlNb powder is 15-55 μm. The mass ratio of mixture 2 and mixture 4 to stainless steel is 2.1-4.4:

1.

5. The high-strength, low-toughness, nanoparticle-reinforced heavy H-beam according to claim 1, characterized in that, The compacting in step (2) is at a pressure of 350-550 MPa for 4-6 min; the sintering is at a temperature of 630-730 DEG C for 2-5 h; the drawing is at a deformation of 10-14% in 11-14 passes; and the electric explosion reaction is in argon protection at an absolute pressure of 0.04-0.06 MPa, a voltage of 15-24 kV, and a current density of 10 5 -10 6 A / mm².

6. The high-strength, low-toughness, nanoparticle-reinforced heavy H-beam according to claim 1, characterized in that, The chemical composition of the H-beam steel mentioned in step (3), by mass percentage, is as follows: C: 0.075-0.115 wt.%; Si: 0.40-0.45 wt.%; Mn: 1.20-1.25 wt.%; P: ≤0.020 wt.%; S: ≤0.009wt.%; Cr: 0.10-0.25wt.%; Ni: 0.15-0.25wt.%; Cu: 0.10-0.25wt.%; V: 0.08-0.09wt.%; Mo: ≤0.07wt.%; Fe: Balance.

7. The high-strength, low-toughness, nanoparticle-reinforced heavy H-beam according to claim 1, characterized in that, The refining in step (3) is as follows: refining time 17-27 min; vacuum treatment is as follows: working vacuum degree 0.2-9.9 kPa, temperature 1582-1618 ℃, degassing time 13-35 min; continuous casting is as follows: liquidus temperature 1521-1529 ℃, superheat control range 11-24 ℃, continuous casting speed 0.55-0.65 m / min, secondary cooling water total pressure control range 10-13 MPa; heat treatment is as follows: holding at 1205-1225 ℃ for 182-298 min; rolling is as follows: total rolling passes 8-12, total reduction 52-68%, rolling per pass 6-9%, rolling temperature ≤940 ℃.

8. The high-strength, low-toughness, nanoparticle-reinforced heavy H-beam according to claim 1, characterized in that, High-strength and low-toughness heavy H-beams reinforced with nanoparticles have a grain size of 8-17μm, a flange thickness of 110-160mm, an impact energy of 210-280J, a yield strength of 465-540MPa, a tensile strength of 595-650MPa, and an elongation of 21-28%.

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