Hot rolling process of high-strength anchor rod reinforcing steel bar

Abstract

The invention discloses a hot rolling process of a high-strength anchor rod steel bar. The hot rolling process comprises the following steps: S1, molten iron pretreatment; s2, molten iron smelting: molten iron, scrap steel and copper are added into a converter, a top-bottom combined blowing converter is adopted for blowing, and the tapping temperature is controlled to be 1620-1670 DEG C, S3, molten iron refining: 4-5 kg / t ferromolybdenum, 2-3 kg / t nickel plate and 1.5-2.5 kg / t ferrovanadium are added into the molten iron in the middle stage of refining; s4, RH vacuum degassing and soft argon blowing, wherein after RH vacuum degassing treatment, a silicon-calcium line is added for purifying molten steel, and then soft argon blowing treatment is conducted; s5, continuous casting: carrying out protective casting on molten steel in the whole process; the temperature of a preheating section is controlled to be 800-900 DEG C, the temperature of a heating section is controlled to be 980-1030 DEG C, and the temperature of a soaking section is controlled to be 1050-1080 DEG C; s7, steel billet rolling; and S8, cooling the anchor rod reinforcing steel bars. The high-strength and high-toughness composite material disclosed by the invention has relatively high strength and toughness and can be completely used under severe natural conditions in the engineering field, and the production method provided by the invention is simple, easy to implement, low in cost and suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metallurgical industry, and particularly relates to a hot rolling process of a high-strength anchor rod steel bar. BACKGROUND

[0002] The anchor rod steel bar is a tensile member used for reinforcing surrounding rock or soil in geotechnical engineering, and enhances the structural stability through prestress effect, and is widely applied in the fields of coal mine roadway, tunnel, slope support and the like. The hot rolling process of the anchor rod steel bar mainly comprises the steps of heating, rolling, controlled cooling and thread processing, and has the advantages of high strength, good toughness and excellent processing performance. The heating is to heat the billet to an austenite state (usually higher than the recrystallization temperature) to ensure the plastic deformation capacity; the rolling comprises finish rolling and rough rolling, the rough rolling is to gradually reduce the size of the billet through multi-pass rolling to form a preliminary shape, the finish rolling is to adopt pre-finish rolling and finish rolling unit to refine the grain through controlled rolling and controlled cooling technology to improve the strength, the controlled cooling is to adopt water cooling devices to grade control cooling before the finish rolling, between the finish rolling units and after the finish rolling to optimize the microstructure, the straightening is to eliminate the bending deformation after rolling to ensure the dimensional accuracy, and the thread processing is to process the steel bar through necking, thread rolling and nut spinning to make it into a mine anchor rod steel product meeting the supporting purpose in the engineering field. At present, with the rapid development of the engineering construction in China, the performance requirements of the anchor rod material are higher and higher in the fields of tunnel and underground engineering, mine engineering, bridge engineering and the like. Since the working environment of the bridge engineering and mine engineering is poor, the anchor rod steel bar used in the field is required to work under the conditions of high pressure and high load, which requires that the anchor rod steel bar used has high strength and high toughness. The 500MPa grade mine anchor rod steel produced in the prior art has the following problems in the process of use: firstly, the content of sulfur and phosphorus in the anchor rod steel bar is not ideal, the content of sulfur and phosphorus is high, the high content of phosphorus will reduce the plasticity, weldability and impact toughness of the anchor rod, phosphorus is easy to segregate at the grain boundary, causing the steel to be "cold brittle", which significantly reduces the low-temperature impact toughness of the steel, and sulfur will cause the steel to be "hot brittle", which will reduce the toughness and strength of the anchor rod steel bar, and brittle fracture will occur in the process of supporting in the engineering field; secondly, in the production process of the existing anchor rod steel bar, expensive alloy elements are generally added to the steel to improve the strength effect, the anchor rod prepared by the above method has a tensile strength of about 700MPa, a yield strength of about 600MPa and an elongation after fracture of less than 2%, and the strength and toughness of the anchor rod steel bar cannot meet the use requirements when the anchor rod is used in the special professional working environment of the bridge engineering and mine engineering. Therefore, it is an objective need to develop a hot rolling process of a high-strength anchor rod steel bar which has a scientific and reasonable production process, can effectively control the production cost and significantly improve the strength and toughness. SUMMARY

[0003] In order to solve the problems in the background art, the purpose of the present application is to provide a hot rolling process of high-strength anchor rod reinforcement which is scientific and reasonable in production process, can effectively control the production cost, and can significantly improve the strength and toughness.

[0004] The hot rolling process of high-strength anchor rod reinforcement according to the present application is carried out in the following steps: S1 Molten iron pretreatment: Before smelting, the KR desulfurization method is used to add a desulfurizing agent for desulfurization treatment in the process of stirring the molten iron, so that the sulfur content of the molten iron entering the furnace is S≤0.003%; S2 Molten iron smelting: The molten iron, scrap steel and copper are added into the converter, and the top and bottom combined blowing converter is used for blowing, and the double slag method is used for operation to realize pre-P removal, so as to ensure that the P content at the end of the converter is ≤0.008%, and the molten steel is sent into the ladle for tapping, and the tapping temperature is controlled at 1620-1670℃, when the molten steel tapping amount reaches 50% of the total amount of molten steel, 0.2-0.3kg / t low-nitrogen carbon additive, 1.5-2.5kg / t low-titanium low-aluminum ferrosilicon, 1.5-2.8kg / t low-carbon chromium iron, and 1.5-2kg / t metal manganese are added for alloying, and the addition is completed when the molten steel tapping amount reaches 80% of the total amount of molten steel, and then the slag removal operation is carried out; S3 Molten iron refining: In the refining process, lime and silicon carbide are used to adjust the slag condition, and no slag surface deoxidization is performed, the refining temperature is controlled at 1600-1650℃, the molten iron is subjected to strong stirring of 450-500NL / min in the early stage of refining, and the molten iron is subjected to weak stirring of 150-200NL / min in the late stage of refining, 4-5kg / t ferromolybdenum, 2-3kg / t nickel plate and 1.5-2.5kg / t vanadium iron are added in the molten iron in the middle stage of refining, and Mo, Ni and V are adjusted to reach the target composition, and low-titanium low-aluminum ferrosilicon and metal manganese are used in the whole process of refining to adjust the Si and Mn contents in the steel; S4 RH vacuum degassing and soft argon blowing: After RH vacuum degassing treatment, silicon-calcium wire is added to purify the molten steel, and then soft argon blowing treatment is carried out; S5 Continuous casting: The molten steel is fully protected during casting, the superheat is ≤35℃, the weak cooling system is used, before entering the straightening machine, the target temperature of the web plate of the casting blank is ≥900℃, the target temperature of the flange of the casting blank is ≥800℃, the constant speed operation is used, and the casting speed is controlled at 2.0-2.5m / min, and the continuous casting blank is cut to obtain a steel blank; S6 Steel blank heating: The steel blank is heated, and during the heating process of the steel blank, the temperature in the preheating section is controlled at 800-900℃, the temperature in the heating section is controlled at 980-1030℃, and the temperature in the soaking section is 1050-1080℃, and the heating time of the steel blank is 50-80min; S7 billet rolling: The roughing rolling temperature is 1000-1040℃. The billet is rough rolled and then cooled through three water-cooled roller conveyors: the first water-cooled roller conveyor has a cooling rate of 150-200℃ / s, cooling to 800-830℃. After passing through the warming roller conveyor, it is cooled to 870-890℃. Then, it passes through the second water-cooled roller conveyor, cooling to 800-830℃. After passing through the warming roller conveyor, it is cooled to 870-890℃. Then, it passes through the third water-cooled roller conveyor, cooling to 800-830℃. After passing through the warming roller conveyor, it is cooled to 900-930℃. Finish rolling begins, with the finish rolling temperature controlled at 920-940℃ and the elongation ratio at 2.7-3.1. The billet is finished to the finished dimensions of the anchor rod reinforcement. S8 Anchor Rod Reinforcement Cooling: The temperature of the finished anchor rod reinforcement after rolling is 930-980℃. After passing through a water-cooled roller conveyor, it is cooled to 820-880℃, and then naturally cooled to room temperature on a cooling bed.

[0005] Furthermore, the chemical composition of the anchor rod steel bar comprises, by mass percentage: C: 0.20–0.23%, Si: 0.8–1.6%, Mn: 1.85–2.15%, Cr: 0.71–0.85%, Ni: 0.21–0.29%, Mo: 0.18–0.28%, Cu: 0.20–0.22%, V: 0.05–0.06%, Al: 0.002–0.025%, P: 0.01–0.015%, S: 0.003–0.004%, with the remainder being Fe and other unavoidable impurities.

[0006] In this invention, cost control and product performance are considered comprehensively. During the iron smelting and refining processes, after alloying the molten iron, relatively inexpensive chromium-molybdenum steel is used to balance cost and performance. Specifically, the reasons for limiting the chemical composition of the steel used to make anchor rod reinforcement in this invention are as follows: C: It can improve the strength and hardenability of steel, considering the requirements of material strength, toughness, and stability. However, a high carbon content will adversely affect the toughness and weldability of the steel. According to production and testing data, a low carbon content results in a low yield strength, while a high carbon content results in a low elongation. Therefore, the carbon content in the steel is controlled within the range of 0.20% to 0.23%. Si: It can dissolve in ferrite and austenite to improve the strength and hardness of steel and is also a deoxidizer. In this invention, it plays a role in improving strength. Mn: It can improve the hardness and wear resistance of steel, significantly improve the hardenability of steel, and improve the hot working performance of steel. It also has the effect of solid solution strengthening, which can expand the austenite region, lower the transformation temperature of austenite to ferrite, and thus refine the ferrite grains and improve the strength and toughness of steel; Cr: can significantly improve the strength, hardness and hardenability of steel; Ni: can lower the critical transformation temperature of steel, reduce the diffusion rate of alloying elements, and significantly improve the low-temperature impact toughness of steel. The higher the Ni content, the better the impact toughness. Ni can also improve the strength of steel while maintaining good plasticity and toughness; Mo: can strengthen ferrite, improve the strength and hardness of steel, and also lower the critical cooling rate of steel, improving the hardenability of steel; Cu: can improve the strength of steel and improve the steel's resistance to atmospheric corrosion. The corrosion resistance of steel is 2 to 5 times that of Cu-free steel when the Cu content is greater than 0.20%. V: mainly exists in steel as carbides and nitrides, its main function is to refine the steel's microstructure and grain size, improving its strength and toughness. Al: Alumina inclusions in steel can cause brittle fracture in bolts, seriously affecting the material's service life. Therefore, this invention strictly controls the residual Al content in steel, aiming to control the Al content below 0.025%. P: causes cold brittleness in steel, reduces its impact toughness, and also worsens its weldability and reduces its plasticity. P is also an element that easily segregates, increasing temper brittleness and reducing fatigue life. To reduce segregation in steel, prevent cold brittle fracture of bolts at low temperatures, and improve bolt fatigue life, phosphorus content above 0.035% will cause phosphorus segregation in steel, reducing its toughness. Therefore, phosphorus content needs to be controlled as low as possible. Sulfur (S) is an element that easily segregates. In steel, it generally exists in the form of FeS. When steel solidifies, FeS precipitates at the primary grain boundaries, causing hot brittleness. S also affects the uniformity of steel properties. Moreover, S mainly exists in steel as non-metallic inclusions, affecting the purity of the steel and reducing bolt fatigue life. Sulfur content above 0.035% will cause sulfur segregation in steel, resulting in "hot brittleness." Therefore, sulfur content should be controlled as low as possible.

[0007] Furthermore, in step S1, the composition of the molten iron before desulfurization is required to be as follows: Si: 0.15-0.5%, P≤0.20%, S≤0.05%, 0.52%≤Mn≤0.85%.

[0008] Furthermore, in step S1: the mass ratio of the desulfurizing agent to molten iron is 1:120-150, and the desulfurizing agent uses passivated magnesium particles with a particle diameter controlled between 0.2 and 0.6 mm, and the content exceeding this range is no more than 5%.

[0009] Furthermore, in step S2, a special steel ladle constructed with aluminum-free magnesia-carbon bricks is used for tapping. A slag-forming agent is used for slag formation during the alloying process of the tapped steel. The slag-forming agent is a mixture of lime and quartz sand, with a mass ratio of lime to quartz sand of 1:0.3 to 0.5. The mass ratio of the slag-forming agent to the molten iron is 1:140 to 150.

[0010] Furthermore, in step S2, the mass ratio of the scrap steel to the molten iron is 1:15 to 30, and the mass ratio of the copper to the molten iron is 1:130 to 150.

[0011] Furthermore, in step S3, while adding ferromolybdenum, nickel plate, and ferrovanadium to the molten iron, lime needs to be added to form slag. The mass ratio of the lime to the mass of the molten iron is 1:140-150 to avoid the slag being too thick and affecting the desulfurization effect.

[0012] Furthermore, in step S4, the molten steel needs to undergo RH vacuum degassing under a vacuum of 70-75 Pa for at least 20 minutes to remove N and O from the molten steel; the soft-blown argon treatment time is at least 20 minutes, and the argon flow rate is controlled at 50-150 NL / min during the soft-blown argon treatment.

[0013] Furthermore, in step S4, the main components of the silicon-calcium wire used to purify the molten steel are: 25-50% Ca, 18-40% Si, and 15-25% Al.

[0014] Compared with existing technologies, the advantages of this device are: First, this invention strictly controls the raw material composition of anchor reinforcement bars. Firstly, it reduces the C and Cr content and increases the Si and Mn content, refining the ferrite grains and improving the steel's strength and toughness. Secondly, it regulates the C, Si, Mn, Cr, and Mo element composition to fully utilize the role of alloying elements, enhancing the strength and toughness of the anchor reinforcement bars and ensuring stability and safety during support. Finally, it precisely controls the Cu, Ni, and V alloying elements in the steel grade, refining the microstructure while improving the steel's strength and impact toughness, ensuring that all performance indicators of the anchor reinforcement bars consistently meet standard requirements. Second, this invention optimizes the hot rolling process. First, it desulfurizes the molten iron entering the furnace, strictly controlling the sulfur content. Then, it controls the iron-to-metal ratio of the molten iron entering the furnace, followed by smelting in the converter. During smelting, it controls the carbon and phosphorus content and the tapping temperature. When the smelted steel enters the ladle, it uses low-titanium, low-aluminum ferrosilicon and metallic manganese to adjust the Si and Mn content. The composition and purity of the molten steel are controlled by strictly controlling the order and timing of the addition of lime and alloys. Next, lime and silicon carbide are used to adjust the slag condition during the refining process, without slag surface deoxidation. In the later stages of refining, weak stirring at 150-200 NL / min is employed to prevent slag from entraining large inclusions in the molten steel, thus reducing inclusions and improving the fluidity and purity of the molten steel. This, in turn, improves the quality and purity of the continuously cast steel billets. Finally, the rolling process is optimized. During rough rolling, water cooling combined with reheating is used after each rough rolling. This allows for the formation of a better ferrite structure within the rolled steel bar, refining the grains and significantly improving the strength and toughness of the steel bar. The anchor steel bar prepared by this invention possesses excellent comprehensive mechanical properties, with a tensile strength exceeding 1000 MPa, a yield strength exceeding 800 MPa, and an elongation after fracture exceeding 20%. Its production method is simple, easy to implement, and low-cost, making it suitable for industrial production. Detailed Implementation

[0015] The present invention will be further described below with reference to embodiments, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention. Example 1

[0016] This embodiment 1 describes a hot rolling process for high-strength anchor rod reinforcement, characterized by the following steps: S1 Hot Metal Pretreatment: The required composition of the hot metal before desulfurization is as follows: Si: 0.15-0.5%, P≤0.20%, S≤0.05%, 0.52%≤Mn≤0.85%. Since Mn exists as MnO, too high a concentration will cause slag overflow, while too low a concentration will result in insufficient oxidizing heat. Since Si exists as SiO2, too low a concentration will result in insufficient heat, while too high a concentration will lead to low slag basicity, which is detrimental to dephosphorization. Before smelting, the hot metal is desulfurized using the KR desulfurization method, adding a desulfurizing agent during the stirring process. Sulfur treatment ensures that the sulfur content (S) in the molten iron fed into the furnace is ≤0.003%, removing all sulfur-containing slag after desulfurization and preventing sulfur reversion when added to the converter. Preferably, the mass ratio of the desulfurizing agent to the molten iron is 1:120. The desulfurizing agent uses passivated magnesium particles with a particle diameter controlled between 0.2 and 0.6 mm, and the content exceeding this range is no more than 5%. Passivated magnesium is a desulfurizing agent used in the prior art. By reacting with sulfur in the molten iron, passivated magnesium forms slag, achieving a better desulfurization effect. S2 Iron Smelting: Molten iron, scrap steel, and copper are added to a converter. The mass ratio of scrap steel to molten iron is 1:15, and the mass ratio of copper to molten iron is 1:130. A 100t converter, as used in existing technology, can be used. The scrap steel used is tailings from self-produced continuous casting cuts, with a sulfur content (S) of ≤ 0.005%. Sludge balls and sinter should not be used in the scrap steel, as their sulfur content reaches 0.4%, which is detrimental to sulfur control during tapping. A top-and-bottom combined blowing converter is used, employing a double-slag method for pre-removal of phosphorus (P), ensuring that the final P content at the converter endpoint is ≤ 0.008%. The smelted steel is then tapped into a ladle at a controlled temperature of 1620℃. A special ladle constructed with aluminum-free magnesia-carbon bricks is used for tapping. A slag-forming agent is used during alloying at the tapping stage. The mixture is a mixture of lime and quartz sand, with a mass ratio of lime to quartz sand of 1:0.3. The mass ratio of the slag-forming agent to molten iron is 1:140. When the amount of molten steel produced reaches 50% of the total amount of molten steel, 0.2 kg / t of low-nitrogen carbon raiser, 1.5 kg / t of low-titanium and low-aluminum ferrosilicon, 1.5 kg / t of low-carbon ferrochrome, and 1.5 kg / t of metallic manganese are added for alloying. The addition is completed when the amount of molten steel produced reaches 80% of the total amount of molten steel, and then the slag removal operation is carried out. S3 Hot Metal Refining: The refining process uses lime and silicon carbide to adjust the slag condition, without slag surface deoxidation. The use of aluminum-containing deoxidizers is strictly prohibited throughout the smelting process. The refining temperature is controlled at 1600℃. In the early stages of refining, the hot metal is strongly stirred at 450 NL / min, while in the later stages, it is weakly stirred at 150 NL / min to prevent slag from entraining large particles in the molten steel. During the middle stages of refining, 4 kg / t ferromolybdenum, 2 kg / t nickel plate, and 1.5 kg / t ferrovanadium are added to the hot metal to adjust Mo, Ni, and V to achieve the target composition. Throughout the refining process, low-titanium, low-aluminum ferrosilicon and metallic manganese are used to adjust the Si and Mn content in the steel. While adding ferromolybdenum, nickel plate, and ferrovanadium to the hot metal, lime is added for slag formation. The mass ratio of lime to hot metal is 1:140 to prevent the slag from becoming too thick and affecting the desulfurization effect. S4RH Vacuum Degassing and Soft Argon Blowing: After RH vacuum degassing, silicon-calcium wire is added to purify the molten steel, followed by soft argon blowing. The molten steel needs to undergo RH vacuum degassing at a vacuum degree of 70 Pa for no less than 20 minutes to remove N and O from the molten steel. The soft argon blowing treatment time is no less than 20 minutes, ensuring that inclusions are fully removed while maintaining the production rhythm. The argon flow rate is controlled at 50 NL / min during soft argon blowing. The silicon-calcium wire used to purify the molten steel mainly consists of 25-50% Ca, 18-40% Si, and 15-25% Al. S5 continuous casting: The molten steel is poured under protective conditions throughout the process, with a superheat of ≤35℃. A weak cooling regime is adopted. Before entering the straightening machine, the target temperature of the web of the billet is ≥900℃ and the target temperature of the flange of the billet is ≥800℃. Constant casting speed is adopted and the casting speed is controlled at 2.0m / min. The continuously cast billet is cut to obtain the steel billet. S6 billet heating: The billet is heated. During the billet heating process, the temperature of the preheating section is controlled at 800-900℃, the temperature of the heating section is controlled at 980℃, and the temperature of the soaking section is controlled at 1050℃. The billet heating time is 80 minutes. S7 billet rolling: The initial rolling temperature of the roughing rolling is 1000℃. The billet is rough rolled and then cooled through three water-cooled roller conveyors: the first water-cooled roller conveyor has a cooling rate of 150℃ / s, cooling to 800℃. After passing through the reheating roller conveyor, it is reheated to 870℃. After passing through the second water-cooled roller conveyor, it is cooled to 800℃. After passing through the reheating roller conveyor, it is reheated to 870℃. After passing through the third water-cooled roller conveyor, it is cooled to 800℃. After passing through the reheating roller conveyor, it is reheated to 900℃ before starting the finish rolling. The finish rolling temperature is controlled at 920℃, with an elongation ratio of 2.7. The finish rolling is carried out to the finished size of the anchor rod reinforcement. During the rough rolling process, water cooling combined with reheating is used after each rough rolling. This can form a better ferrite structure inside the rolled reinforcement, which can play a role in refining the grains and can significantly improve the strength and toughness of the reinforcement. S8 Anchor Rod Reinforcement Cooling: The finished anchor rod reinforcement is rolled at a temperature of 930℃. After being cooled to 820℃ via a water-cooled roller conveyor, it is then naturally cooled to room temperature on a cooling bed.

[0017] The anchor reinforcement prepared by the above method has the following chemical composition by mass percentage: C: 0.20-0.23%, Si: 0.8-1.6%, Mn: 1.85-2.15%, Cr: 0.71-0.85%, Ni: 0.21-0.29%, Mo: 0.18-0.28%, Cu: 0.20-0.22%, V: 0.05-0.06%, Al: 0.002-0.025%, P: 0.01-0.015%, S: 0.003-0.004%, with the remainder being Fe and other unavoidable impurities.

[0018] In this embodiment 1, by strictly controlling the synergistic effect between P and S, C and Si, Mn, Cr, Mo, Cu, Ni, and V alloying elements, it possesses excellent comprehensive mechanical properties. The surface quality of the anchor rod steel bars produced in this embodiment 1 was inspected, and no obvious surface quality defects were found during the inspection process, indicating good surface quality. At the same time, the mechanical properties were tested, and the tensile strength reached 1020 MPa, the yield strength reached 815 MPa, and the elongation after fracture reached 22.3%. The rolled anchor rod steel bars have high strength and toughness, and this anchor has good support capabilities, making it fully capable of being used in harsh natural conditions in the engineering field. Furthermore, the production method provided by this invention is simple, easy to implement, low in cost, and suitable for industrial production. Example 2

[0019] This embodiment 2 describes a hot rolling process for high-strength anchor rod reinforcement, characterized by the following steps: S1 Hot Metal Pretreatment: The required composition of the hot metal before desulfurization is as follows: Si: 0.15-0.5%, P≤0.20%, S≤0.05%, 0.52%≤Mn≤0.85%. Since Mn exists as MnO, too high a concentration will cause slag overflow, while too low a concentration will result in insufficient oxidizing heat. Since Si exists as SiO2, too low a concentration will result in insufficient heat, while too high a concentration will lead to low slag basicity, which is detrimental to dephosphorization. Before smelting, the hot metal is desulfurized using the KR desulfurization method, adding a desulfurizing agent during the stirring process. Sulfur treatment ensures that the sulfur content (S) of the molten iron entering the furnace is ≤0.003%, removing all sulfur-containing slag after desulfurization and preventing sulfur reversion when added to the converter. Preferably, the mass ratio of the desulfurizing agent to the molten iron is 1:135. The desulfurizing agent uses passivated magnesium particles with a particle diameter controlled between 0.2 and 0.6 mm, and the content exceeding this range is no more than 5%. Passivated magnesium is a desulfurizing agent used in the prior art. By reacting with sulfur in the molten iron, passivated magnesium forms slag, achieving a better desulfurization effect. S2 Iron Smelting: Molten iron, scrap steel, and copper are added to a converter. The mass ratio of scrap steel to molten iron is 1:15-30, and the mass ratio of copper to molten iron is 1:140. A 100t converter, as used in existing technology, can be used. The scrap steel used is tailings from self-produced continuous casting cuts, with an sulfur content of ≤0.005%. Sludge balls and sinter should not be used in the scrap steel, as their sulfur content reaches 0.4%, which is detrimental to sulfur control during tapping. A top-and-bottom combined blowing converter is used, employing a double-slag method for pre-removal of phosphorus (P), ensuring that the final P content at the converter endpoint is ≤0.008%. The smelted molten steel is then fed into a ladle for tapping. The steel temperature is controlled at 1650℃. A special steel ladle with aluminum-free magnesia-carbon bricks is used for tapping. A slag-forming agent is needed for alloying during tapping. The slag-forming agent is a mixture of lime and quartz sand with a mass ratio of lime to quartz sand of 1:0.4. The mass ratio of the slag-forming agent to molten iron is 1:145. When the tapping volume of molten steel reaches 50% of the total molten steel, 0.25 kg / t of low-nitrogen carbon raiser, 2 kg / t of low-titanium and low-aluminum ferrosilicon, 2.5 kg / t of low-carbon ferrochrome, and 1.8 kg / t of metallic manganese are added for alloying. The addition is completed when the tapping volume of molten steel reaches 80% of the total molten steel, and then the slag removal operation is carried out. S3 Hot Metal Refining: The refining process uses lime and silicon carbide to adjust the slag condition, without slag surface deoxidation. The use of aluminum-containing deoxidizers is strictly prohibited throughout the smelting process. The refining temperature is controlled at 1630℃. In the early stages of refining, the hot metal is strongly stirred at 480 NL / min, while in the later stages, it is weakly stirred at 180 NL / min to prevent slag from entraining large particles in the molten steel. During the middle stages of refining, 4.5 kg / t ferromolybdenum, 2.5 kg / t nickel plate, and 2 kg / t ferrovanadium are added to the hot metal to adjust Mo, Ni, and V to the target composition. Throughout the refining process, low-titanium, low-aluminum ferrosilicon and metallic manganese are used to adjust the Si and Mn content in the steel. While adding ferromolybdenum, nickel plate, and ferrovanadium to the hot metal, lime is added for slag formation. The mass ratio of lime to hot metal is 1:145 to prevent the slag from becoming too thick and affecting the desulfurization effect. S4RH Vacuum Degassing and Soft Argon Blowing: After RH vacuum degassing, silicon-calcium wire is added to purify the molten steel, followed by soft argon blowing. The molten steel needs to undergo RH vacuum degassing at a vacuum degree of 72 Pa for no less than 20 minutes to remove N and O from the molten steel. The soft argon blowing treatment time is no less than 20 minutes, ensuring that inclusions are fully removed while maintaining production rhythm. The argon flow rate is controlled at 100 NL / min during soft argon blowing. The silicon-calcium wire used to purify the molten steel mainly consists of 25-50% Ca, 18-40% Si, and 15-25% Al. S5 continuous casting: The molten steel is poured under protective conditions throughout the process, with a superheat of ≤35℃. A weak cooling regime is adopted. Before entering the straightening machine, the target temperature of the web of the billet is ≥900℃ and the target temperature of the flange of the billet is ≥800℃. Constant casting speed is adopted and the casting speed is controlled at 2.2m / min. The continuously cast billet is cut to obtain the steel billet. S6 billet heating: The billet is heated. During the billet heating process, the temperature of the preheating section is controlled at 850℃, the temperature of the heating section is controlled at 1000℃, and the temperature of the soaking section is controlled at 1060℃. The billet heating time is 70 minutes. S7 billet rolling: The roughing rolling temperature is 1020℃. The billet is rough rolled and then cooled through three water-cooled roller conveyors: the first water-cooled roller conveyor has a cooling rate of 180℃ / s, cooling to 820℃. After passing through the warming roller conveyor, it is cooled to 880℃. After passing through the second water-cooled roller conveyor, it is cooled to 820℃. After passing through the warming roller conveyor, it is cooled to 880℃. After passing through the third water-cooled roller conveyor, it is cooled to 820℃. After passing through the warming roller conveyor, it is cooled to 915℃. Then, the finishing rolling begins. The finishing rolling temperature is controlled at 930℃, the elongation ratio is 2.9, and the finishing rolling is carried out to the finished size of the anchor rod steel bar. S8 Anchor Rod Reinforcement Cooling: The finished anchor rod reinforcement is rolled at 950℃. After being cooled to 850℃ by water-cooled rollers, it is naturally cooled to room temperature on a cooling bed.

[0020] The anchor reinforcement prepared by the above method has the following chemical composition by mass percentage: C: 0.20-0.23%, Si: 0.8-1.6%, Mn: 1.85-2.15%, Cr: 0.71-0.85%, Ni: 0.21-0.29%, Mo: 0.18-0.28%, Cu: 0.20-0.22%, V: 0.05-0.06%, Al: 0.002-0.025%, P: 0.01-0.015%, S: 0.003-0.004%, with the remainder being Fe and other unavoidable impurities.

[0021] In this embodiment 2, by strictly controlling the synergistic effect between P and S, C and Si, Mn, Cr, Mo, Cu, Ni, and V alloying elements, it possesses excellent comprehensive mechanical properties. The surface quality of the anchor rod steel bars produced in this embodiment 2 was inspected, and no obvious surface quality defects were found during the inspection process, indicating good surface quality. At the same time, the mechanical properties were tested, and the tensile strength reached 1100MPa, the yield strength reached 850MPa, and the elongation after fracture reached 25.7%. The rolled anchor rod steel bars have high strength and toughness, and this anchor has good support capabilities, making it fully capable of being used in harsh natural conditions in the engineering field. Furthermore, the production method provided by this invention is simple, easy to implement, low in cost, and suitable for industrial production. Example 3

[0022] This embodiment 3 describes a hot rolling process for high-strength anchor rod reinforcement, characterized by the following steps: S1 Hot Metal Pretreatment: The required composition of the hot metal before desulfurization is as follows: Si: 0.15-0.5%, P≤0.20%, S≤0.05%, 0.52%≤Mn≤0.85%. Since Mn exists as MnO, too high a concentration will cause slag overflow, while too low a concentration will result in insufficient oxidizing heat. Since Si exists as SiO2, too low a concentration will result in insufficient heat, while too high a concentration will lead to low slag basicity, which is detrimental to dephosphorization. Before smelting, the hot metal is desulfurized using the KR desulfurization method, adding a desulfurizing agent during the stirring process. Sulfur treatment ensures that the sulfur content (S) in the molten iron fed into the furnace is ≤0.003%, removing all sulfur-containing slag after desulfurization and preventing sulfur reversion when added to the converter. Preferably, the mass ratio of the desulfurizing agent to the molten iron is 1:150. The desulfurizing agent uses passivated magnesium particles with a particle diameter controlled between 0.2 and 0.6 mm, and the content exceeding this range is no more than 5%. Passivated magnesium is a desulfurizing agent used in existing technologies. By reacting with sulfur in the molten iron, passivated magnesium forms slag, achieving a better desulfurization effect. S2 Iron Smelting: Molten iron, scrap steel, and copper are added to a converter. The mass ratio of scrap steel to molten iron is 1:15-30, and the mass ratio of copper to molten iron is 1:150. A 100t converter, as used in existing technology, can be used. The scrap steel used is tailings from self-produced continuous casting cuts, with an sulfur content of ≤0.005%. Sludge balls and sinter should not be used in the scrap steel, as their sulfur content reaches 0.4%, which is detrimental to sulfur control during tapping. A top-and-bottom blowing converter is used, employing a double-slag method for pre-removal of phosphorus (P), ensuring that the final P content at the converter endpoint is ≤0.008%. The smelted steel is then tapped into a ladle at a controlled temperature of 1670℃. A special ladle constructed with aluminum-free magnesia-carbon bricks is used for tapping. A slag-forming agent is used during alloying at the tapping stage. The slag is a mixture of lime and quartz sand, with a mass ratio of lime to quartz sand of 1:0.5. The mass ratio of the slag-forming agent to molten iron is 1:150. When the amount of molten steel tapped reaches 50% of the total amount of molten steel, 0.3 kg / t of low-nitrogen carbon raiser, 2.5 kg / t of low-titanium and low-aluminum ferrosilicon, 2.8 kg / t of low-carbon ferrochrome, and 2 kg / t of metallic manganese are added for alloying. The addition is completed when the amount of molten steel tapped reaches 80% of the total amount of molten steel, and then the slag removal operation is carried out. S3 Hot Metal Refining: The refining process uses lime and silicon carbide to adjust the slag condition, without slag surface deoxidation. The use of aluminum-containing deoxidizers is strictly prohibited throughout the smelting process. The refining temperature is controlled at 1650℃. In the early stages of refining, the hot metal is strongly stirred at 500 NL / min, while in the later stages, it is weakly stirred at 200 NL / min to prevent slag from entraining large particles in the molten steel. During the middle stages of refining, 5 kg / t ferromolybdenum, 3 kg / t nickel plate, and 2.5 kg / t ferrovanadium are added to the hot metal to adjust Mo, Ni, and V to achieve the target composition. Throughout the refining process, low-titanium, low-aluminum ferrosilicon and metallic manganese are used to adjust the Si and Mn content in the steel. While adding ferromolybdenum, nickel plate, and ferrovanadium to the hot metal, lime is added for slag formation. The mass ratio of the lime to the hot metal is 1:150 to prevent the slag from becoming too thick and affecting the desulfurization effect. S4RH Vacuum Degassing and Soft Argon Blowing: After RH vacuum degassing, silicon-calcium wire is added to purify the molten steel, followed by soft argon blowing. The molten steel needs to undergo RH vacuum degassing at a vacuum degree of 75 Pa for no less than 20 minutes to remove N and O from the molten steel. The soft argon blowing treatment time is no less than 20 minutes, ensuring that inclusions are fully removed while maintaining the production rhythm. The argon flow rate is controlled at 150 NL / min during soft argon blowing. The silicon-calcium wire used to purify the molten steel mainly consists of 25-50% Ca, 18-40% Si, and 15-25% Al. S5 continuous casting: The molten steel is poured under protective conditions throughout the process, with a superheat of ≤35℃. A weak cooling regime is adopted. Before entering the straightening machine, the target temperature of the web of the billet is ≥900℃ and the target temperature of the flange of the billet is ≥800℃. Constant casting speed is adopted and the casting speed is controlled at 2.5m / min. The continuously cast billet is cut to obtain the steel billet. S6 billet heating: The billet is heated. During the billet heating process, the temperature of the preheating section is controlled at 800-900℃, the temperature of the heating section is controlled at 1030℃, and the temperature of the soaking section is controlled at 1080℃. The billet heating time is 50 minutes. S7 billet rolling: The roughing rolling temperature is 1040℃. The billet is rough rolled and then cooled through three water-cooled roller conveyors: the first water-cooled roller conveyor has a cooling rate of 200℃ / s, cooling to 830℃. After passing through the warming roller conveyor, it is cooled to 890℃. After passing through the second water-cooled roller conveyor, it is cooled to 830℃. After passing through the warming roller conveyor, it is cooled to 890℃. After passing through the third water-cooled roller conveyor, it is cooled to 830℃. After passing through the warming roller conveyor, it is cooled to 930℃. Then, the finishing rolling begins. The finishing rolling temperature is controlled at 940℃, the elongation ratio is 3.1, and the finishing rolling is carried out to the finished size of the anchor rod steel bar. S8 Anchor Rod Reinforcement Cooling: The finished anchor rod reinforcement is rolled at a temperature of 980℃. It is cooled to 880℃ via a water-cooled roller conveyor and then naturally cooled to room temperature on a cooling bed.

[0023] The anchor reinforcement prepared by the above method has the following chemical composition by mass percentage: C: 0.20-0.23%, Si: 0.8-1.6%, Mn: 1.85-2.15%, Cr: 0.71-0.85%, Ni: 0.21-0.29%, Mo: 0.18-0.28%, Cu: 0.20-0.22%, V: 0.05-0.06%, Al: 0.002-0.025%, P: 0.01-0.015%, S: 0.003-0.004%, with the remainder being Fe and other unavoidable impurities.

[0024] In this embodiment 3, by strictly controlling the synergistic effect between P and S, C and Si, Mn, Cr, Mo, Cu, Ni, and V alloying elements, it possesses excellent comprehensive mechanical properties. The surface quality of the anchor rod steel bars produced in this embodiment 3 was inspected, and no obvious surface quality defects were found during the inspection process, indicating good surface quality. At the same time, the mechanical properties were tested, and the tensile strength reached 1085 MPa, the yield strength reached 832 MPa, and the elongation after fracture reached 26.3%. The rolled anchor rod steel bars have high strength and toughness, and this anchor has good support capabilities, making it fully capable of being used in harsh natural conditions in the engineering field. Furthermore, the production method provided by this invention is simple, easy to implement, low in cost, and suitable for industrial production.

Claims

1. A hot rolling process for high-strength anchor rod reinforcing bars, characterized in that: Follow these steps: S1 Hot Metal Pretreatment: Before smelting, the hot metal is desulfurized using the KR desulfurization method. A desulfurizing agent is added during the stirring of the hot metal to achieve desulfurization treatment, so that the sulfur content of the hot metal entering the furnace is S≤0.003%. S2 molten iron smelting: Molten iron, scrap steel, and copper are added to the converter, and top and bottom blowing are used for converter smelting. The double slag method is used to achieve pre-removal of phosphorus (P), ensuring that the final P content of the converter is ≤0.008%. The smelted molten steel is sent to the ladle for tapping. The tapping temperature is controlled at 1620~1670℃. When the amount of molten steel tapped reaches 50% of the total amount of molten steel, 0.2~0.3kg / t of low-nitrogen carbon raiser, 1.5~2.5kg / t of low-titanium and low-aluminum ferrosilicon, 1.5~2.8kg / t of low-carbon ferrochrome, and 1.5~2kg / t of metallic manganese are added for alloying. The addition is completed when the amount of molten steel tapped reaches 80% of the total amount of molten steel. After that, the slag removal operation is carried out. S3 Hot Metal Refining: The refining process uses lime and silicon carbide to adjust the slag condition, without slag surface deoxidation. The refining temperature is controlled at 1600-1650℃. In the early stage of refining, the hot metal is strongly stirred at 450-500 NL / min, and in the later stage of refining, the hot metal is weakly stirred at 150-200 NL / min. In the middle stage of refining, 4-5 kg / t ferromolybdenum, 2-3 kg / t nickel plate and 1.5-2.5 kg / t ferrovanadium are added to the hot metal to adjust the Mo, Ni and V to achieve the target composition. Throughout the refining process, low-titanium, low-aluminum ferrosilicon and metallic manganese are used to adjust the Si and Mn content in the steel. S4RH vacuum degassing and soft argon blowing: After RH vacuum degassing, silicon-calcium wire is added to purify the molten steel, followed by soft argon blowing treatment. S4 continuous casting: The molten steel is poured under protective conditions throughout the process, with a superheat of ≤35℃. A weak cooling regime is adopted. Before entering the straightening machine, the target temperature of the web of the billet is ≥900℃ and the target temperature of the flange of the billet is ≥800℃. Constant casting speed operation is adopted, with the casting speed controlled at 2.0~2.5m / min. The continuously cast billet is cut to obtain the steel billet. S6 billet heating: The billet is heated. During the billet heating process, the temperature of the preheating section is controlled at 800-900℃, the temperature of the heating section is controlled at 980-1030℃, and the temperature of the soaking section is controlled at 1050-1080℃. The billet heating time is 50-80 minutes. S7 billet rolling: The roughing rolling temperature is 1000-1040℃. The billet is rough rolled and then cooled through three water-cooled roller conveyors: the first water-cooled roller conveyor has a cooling rate of 150-200℃ / s, cooling to 800-830℃. After passing through the warming roller conveyor, it is cooled to 870-890℃. Then, it passes through the second water-cooled roller conveyor, cooling to 800-830℃. After passing through the warming roller conveyor, it is cooled to 870-890℃. Then, it passes through the third water-cooled roller conveyor, cooling to 800-830℃. After passing through the warming roller conveyor, it is cooled to 900-930℃. Finish rolling begins, with the finish rolling temperature controlled at 920-940℃ and the elongation ratio at 2.7-3.

1. The billet is finished to the finished dimensions of the anchor rod reinforcement. S8 Anchor Rod Reinforcement Cooling: The temperature of the finished anchor rod reinforcement after rolling is 930-980℃. After passing through a water-cooled roller conveyor, it is cooled to 820-880℃, and then naturally cooled to room temperature on a cooling bed.

2. The hot rolling process for high-strength anchor rod reinforcement according to claim 1, characterized in that: The chemical composition of the anchor rod steel bars comprises, by mass percentage: C: 0.10–0.18%, Si: 0.8–1.6%, Mn: 1.85–2.15%, Cr: 0.71–0.85%, Ni: 0.21–0.29%, Mo: 0.18–0.28%, Cu: 0.16–0.21%, V: 0.05–0.06%, Al: 0.002–0.03%, P: 0.01–0.015%, S: 0.003–0.004%, with the remainder being Fe and other unavoidable impurities.

3. The hot rolling process for high-strength anchor rod reinforcement according to claim 1, characterized in that: In step S1, the composition of the molten iron before desulfurization is required to be as follows: Si: 0.15-0.5%, P≤0.20%, S≤0.05%, 0.52%≤Mn≤0.85%.

4. The hot rolling process for high-strength anchor rod reinforcement according to claim 1, characterized in that: In step S1: the mass ratio of the desulfurizing agent to molten iron is 1:120-150, and the desulfurizing agent uses passivated magnesium particles with a particle diameter controlled between 0.2 and 0.6 mm. The content of particles exceeding this range is no more than 5%.

5. The hot rolling process for high-strength anchor rod reinforcement according to claim 1, characterized in that: In step S2, a special steel ladle constructed with aluminum-free magnesia-carbon bricks is used for tapping. A slag-forming agent is used for slag formation during the alloying process of the tapped steel. The slag-forming agent is a mixture of lime and quartz sand, with a mass ratio of lime to quartz sand of 1:0.3 to 0.

5. The mass ratio of the slag-forming agent to the molten iron is 1:140 to 150.

6. The hot rolling process for high-strength anchor rod reinforcement according to claim 1, characterized in that: In step S2, the mass ratio of the scrap steel to the molten iron is 1:10 to 20, and the mass ratio of the copper to the molten iron is 1:130 to 150.

7. The hot rolling process for high-strength anchor rod reinforcement according to claim 1, characterized in that: In step S3, while adding ferromolybdenum, nickel plate, and ferrovanadium to the molten iron, lime needs to be added to form slag. The mass ratio of the lime to the molten iron is 1:140-150 to avoid the slag being too thick and affecting the desulfurization effect.

8. The hot rolling process for high-strength anchor rod reinforcement according to claim 1, characterized in that: In step S4, the molten steel needs to undergo RH vacuum degassing under a vacuum degree of 70-75 Pa for no less than 20 minutes to remove N and O from the molten steel. The soft-blown argon treatment time shall not be less than 20 minutes, and the argon flow rate during the soft-blown argon treatment shall be controlled at 50-150 NL / min.

9. The hot rolling process for high-strength anchor rod reinforcement according to claim 1, characterized in that: In step S4, the main components of the silicon-calcium wire used to purify the molten steel are: 25-50% Ca, 18-40% Si, and 15-25% Al.