Preparation process for smelting anchor rod steel bar

Abstract

The invention relates to the technical field of anchor rod machining, and discloses a preparation process for anchor rod steel bar smelting, which comprises the following process steps: S1, molten iron preparation, S2, converter smelting, S3, LF refining, S4, continuous casting and S5, rolling, the process can improve the product quality: through strict process control, an MG500 anchor rod steel finished product is accurate and stable in chemical component and excellent in mechanical property, the tensile strength reaches about 700MPa, and the tensile strength reaches about 700MPa; and the yield strength exceeds 550MPa, the percentage elongation after fracture exceeds 20%, the impact energy exceeds 65J, and low-power inspection and metallographic structure rating are excellent. The high strength, high toughness and good anti-fatigue performance are far better than those of common anchor rod steel, the underground support reliability and durability are effectively enhanced, the coal mining safety is powerfully guaranteed, the process economic benefits are remarkable, although the cost of MG500 alloy and refining is increased, the benefits are continuously increased along with market expansion and yield increase, meanwhile, production is stable, waste products and rework are reduced, and the production cost is reduced. Production cost is reduced, and resource utilization rate and enterprise revenue are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bolt processing, and specifically to a preparation process for the smelting of bolt steel bars. Background Art

[0002] Under the situation of the booming development of the coal industry and the continuous improvement of safety management requirements, hot-rolled ribbed steel bars for bolts, as key materials for underground support, have continuously rising demand and quality standards. The working environment of coal mining operations is complex and harsh, with extremely high requirements for the strength, toughness and reliability of support materials to ensure roadway stability and personnel safety.

[0003] In the past, although the steel bar production line had a certain production capacity for hot-rolled ribbed steel bars, the production technology of hot-rolled ribbed steel bars MG500 for bolts was not yet mature. In terms of chemical composition regulation, it was difficult to accurately determine the proportion of each element to meet the performance requirements of MG500; in the smelting process, the accuracy of converter end-point control was poor, and the parameter optimization in the refining process was insufficient, resulting in limited molten steel purity and composition stability; in the continuous casting and rolling processes, the adaptability of the mold powder, the rationality of cooling water distribution and the scientific nature of the temperature regime were lacking, frequently causing billet defects and fluctuations in steel performance, and unable to stably supply high-quality MG500 bolt steel, which was difficult to meet the increasingly stringent standards of the coal industry for underground support materials, restricting the market competitiveness and development potential of enterprises in this field. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] Aiming at the deficiencies of the prior art, the present invention provides a preparation process for the smelting of bolt steel bars, which has the advantages of improving product quality, etc., and solves the problems that in terms of chemical composition regulation, it is difficult to accurately determine the proportion of each element to meet the performance requirements of MG500; in the smelting process, the accuracy of converter end-point control is poor, and the parameter optimization in the refining process is insufficient.

[0006] (II) Technical Solutions

[0007] To achieve the above object, the present invention provides the following technical solutions: A preparation process for the smelting of bolt steel bars, including the following process steps, S1 hot metal preparation, S2 converter smelting, S3 LF refining, S4 continuous casting and S5 rolling. The S1 hot metal preparation: Ensure that the quality of the hot metal meets the smelting requirements, providing a basis for subsequent reactions, and its composition and temperature indicators need to be stable;

[0008] S2 converter smelting;

[0009] End-point control: Strictly control the tapping temperature of the converter at 1591 - 1665 °C, the C content at 0.08 - 0.15%, the Mn content at 0.07 - 0.14%, the P content at 0.011 - 0.021%, and the S content at 0.019 - 0.023%;

[0010] During the tapping process, only ferrosilicon and silicomanganese are used for deoxidation alloying. Lime and fluorite are added as top slag materials. Fluorite is added first and then lime. The addition amount of lime is 1 kg / ton, and the amount of fluorite is 20 kg / furnace. Precise end-point control can ensure that the molten steel composition meets the requirements of MG500, laying a foundation for subsequent refining.

[0011] S3LF refining;

[0012] Parameter control: The heating rate during the refining process is relatively slow. The addition amount of quicklime is 2 kg per ton of steel, the power-on time is 20 min, and the entire refining cycle is 35 min. Reasonable refining parameters can effectively remove impurities in the molten steel, further adjust the composition, and improve the purity of the molten steel.

[0013] Composition adjustment: According to the internal control standard of MG500, the composition of the molten steel is accurately adjusted. By adding appropriate alloys, the composition is ensured to be stable, meeting the performance requirements of anchor steel.

[0014] S4 continuous casting;

[0015] Mold powder: HRB400E mold powder is used and fully baked before use to ensure its stable performance, effectively prevent oxidation of the molten steel and adhesion to the mold wall, and ensure the surface quality of the slab.

[0016] Secondary cooling water distribution: The water is distributed at 1.9 - 2.0 L / kg. The water volume in the mold is 135 t / h, the flow rate of the full roller water is 21.3 t / h, the first segment is 20.5 t / h, the second segment is 9 t / h, and the third segment is 3 t / h (casting speed 2.55 m / min). Reasonable cooling water volume can uniformly cool the slab, avoid the generation of internal cracks, and ensure the compact internal structure of the slab.

[0017] Casting speed and electromagnetic stirring: The casting speed is controlled at 2.3 - 2.6 m / min, the temperature difference in the mold is 5 - 7 °C. At the same time, mold electromagnetic stirring is put into operation, with a current of 240 A, a voltage of 150 V, and a frequency of 4.0 HZ. The continuous stirring mode is adopted. Appropriate casting speed and electromagnetic stirring can improve the solidification structure of the slab, reduce segregation and defects.

[0018] Tundish temperature control: The liquidus temperature of MG500 is calculated according to 1503 °C.

[0019] Preferably, during the S2 converter smelting process operation: During the tapping process, closely monitor the reaction of the molten steel to ensure the effect of deoxidation alloying, stabilize the composition and temperature of the molten steel, and prevent the influence of composition deviation on the performance of the steel.

[0020] Preferably, the tundish temperature is controlled at 1519 - 1555 °C, with an average value of 1531 °C and a superheat of 28 °C. Stable tundish temperature helps to stabilize the quality of the slab and prevent defects caused by temperature fluctuations.

[0021] Preferably, the parameters are controlled as follows: the composition of the refined slag sample is controlled within a specific range, such as Al2O3 2.03%, CaO 56.45%, MnO 0.29%, MgO 7.35%, SiO2 25.50%, TFe 1.64%, R 2.21%, and the fixed oxygen content is 19ppm, basically achieving white slag steelmaking.

[0022] Preferably, the composition adjustment: according to the MG500 internal control standard, the composition of the molten steel is accurately adjusted, such as the C content is controlled at 0.23-0.27%, the Si content is 0.40-0.55%, the Mn content is 1.40-1.57%, the P content is ≤0.035%, the S content is ≤0.035%, and the V content is ≥0.050%. By adding suitable alloys, the composition is ensured to be stable and the performance requirements of the anchor steel are met.

[0023] (III) Beneficial effects

[0024] Compared with the prior art, the present invention provides a preparation process for smelting anchor steel bars, which has the following beneficial effects:

[0025] 1. The preparation process for smelting anchor steel bars can improve product quality: after strict process control, the chemical composition of the finished MG500 anchor steel is accurate and stable, with excellent mechanical properties, tensile strength of about 700MPa, yield strength of over 550MPa, elongation after fracture of over 20%, impact energy of over 65J, and excellent low-power inspection and metallographic structure rating. Its high strength, high toughness and good fatigue resistance far exceed ordinary anchor steel, effectively enhancing the reliability and durability of underground support, and effectively ensuring the safety of coal mining.

[0026] 2. The preparation process for smelting anchor steel bars has significant economic benefits: despite the increase in MG500 alloy and refining costs, the profit per ton of steel increases by about RMB 90 due to the higher selling price. In some periods of 2023, 4,879 tons were produced, creating an economic benefit of RMB 440,000. With market expansion and output growth, the benefits continue to rise. At the same time, stable production reduces scrap and rework, reduces production costs, and improves resource utilization and corporate benefits.

[0027] 3. The preparation process for smelting anchor steel bars has enhanced market competitiveness: the successful development of MG500 anchor steel enriches the product range, meets the high-end needs of the coal industry, enhances the company's visibility and influence in the anchor steel market, attracts more customer orders, expands market share, consolidates the company's position in the industry, lays a solid foundation for long-term development, and helps the company stand out in the fierce market competition and achieve sustainable development. DETAILED DESCRIPTION

[0028] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] This solution provides a technical solution, specifically, a preparation process for the smelting of anchor bar steel, including the following process steps. The following are the preparation process steps developed based on the MG500 anchor bar steel in the material:

[0030] S1 Molten iron preparation: Ensure that the quality of the molten iron meets the smelting requirements to provide a basis for subsequent reactions. Its composition and temperature and other indicators need to be stable. For example, the content of elements such as silicon and manganese in the molten iron should be within a suitable range, and the temperature needs to reach a specific value to ensure the smooth progress of the smelting process;

[0031] S2 Converter smelting;

[0032] Endpoint control: Strictly control the tapping temperature of the converter at 1591 - 1665 °C, the C content at 0.08 - 0.15%, the Mn content at 0.07 - 0.14%, the P content at 0.011 - 0.021%, and the S content at 0.019 - 0.023%;

[0033] During the tapping process, only ferrosilicon and silicomanganese are used for deoxidation alloying. Add top slag materials lime and fluorite. Add fluorite first and then lime. The addition amount of lime is 1 kg / ton, and the fluorite is 20 kg / furnace. Precise endpoint control can ensure that the composition of the molten steel meets the requirements of MG500, laying a foundation for subsequent refining;

[0034] Process operation: During the tapping process, closely monitor the reaction of the molten steel to ensure the effect of deoxidation alloying, stabilize the composition and temperature of the molten steel, and prevent component deviation from affecting the performance of the steel;

[0035] S3 LF refining;

[0036] Parameter control: The heating rate during the refining process is relatively slow. The addition amount of white lime is added at 2 kg per ton of steel, the power-on time is about 20 min, and the entire refining cycle is about 35 min. The composition of the refining slag sample is controlled within a specific range, such as Al2O3 about 2.03%, CaO about 56.45%, MnO about 0.29%, MgO about 7.35%, SiO2 about 25.50%, TFe about 1.64%, R about 2.21%, and the oxygen content is 19 ppm, basically achieving tapping with white slag. Reasonable refining parameters can effectively remove impurities in the molten steel, further adjust the composition, and improve the purity of the molten steel;

[0037] Composition adjustment: According to the internal control standards of MG500, the composition of molten steel is accurately adjusted. For example, the C content is controlled at 0.23 - 0.27%, the Si content at 0.40 - 0.55%, the Mn content at 1.40 - 1.57%, the P content ≤ 0.035%, the S content ≤ 0.035%, and the V content ≥ 0.050%. By adding appropriate alloys, the composition is ensured to be stable, meeting the performance requirements of anchor steel;

[0038] Continuous casting in S4;

[0039] Mold powder: HRB400E mold powder is used and fully baked before use to ensure its stable performance, effectively preventing oxidation of molten steel and sticking to the mold wall, and ensuring the surface quality of the slab;

[0040] Secondary cooling water distribution: The water is distributed at 1.9 - 2.0 L / kg. The water volume in the mold is 135 t / h, the water flow rate of the full roller is 21.3 t / h, the first stage is 20.5 t / h, the second stage is 9 t / h, and the third stage is 3 t / h (casting speed 2.55 m / min). Reasonable cooling water volume can cool the slab evenly, avoid the generation of internal cracks, and ensure the compact internal structure of the slab;

[0041] Casting speed and electromagnetic stirring: The casting speed is controlled at 2.3 - 2.6 m / min, the temperature difference of the mold water is about 5 - 7 °C. At the same time, mold electromagnetic stirring is put into operation, with a current of 240 A, a voltage of 150 V, and a frequency of 4.0 HZ. The continuous stirring mode is adopted. Appropriate casting speed and electromagnetic stirring can improve the solidification structure of the slab, reduce segregation and defects;

[0042] Tundish temperature control: According to the calculation, the liquidus line of MG500 is 1503 °C. The tundish temperature is controlled at 1519 - 1555 °C, with an average value of 1531 °C and a superheat of 28 °C. Stable tundish temperature helps to ensure the stability of slab quality and prevent defects caused by temperature fluctuations;

[0043] Rolling in S5;

[0044] Heating furnace temperature regime: The temperature in the heating section is controlled at 1040 - 1080 °C, the soaking section (head) at 1060 - 1080 °C, and the soaking section (tail) at 1070 - 1100 °C. Reasonable heating temperature can heat the billet evenly, provide good plastic conditions for rolling, and ensure uniform steel performance;

[0045] Rolling line temperature control: The rolling start temperature (at the exit of the first roughing stand) is 1040 - 1080 °C, the temperature entering the finishing mill is 960 - 980 °C, and the temperature on the cooling bed is 900 - 930 °C. Strict rolling line temperature control can ensure that the structure and performance of the steel meet the requirements and obtain good mechanical properties.

[0046] Furthermore, this process can improve product quality: Through strict process control, the chemical composition of the finished MG500 bolt steel is precisely stable, with excellent mechanical properties. The tensile strength reaches about 700 MPa, the yield strength exceeds 550 MPa, the elongation after fracture exceeds 20%, the impact energy exceeds 65 J, and the macrostructure inspection and metallographic structure rating are excellent. Its high strength, high toughness, and good fatigue resistance far exceed those of ordinary bolt steel, effectively enhancing the reliability and durability of underground support and strongly ensuring the safety of coal mining.

[0047] Furthermore, this process has significant economic benefits: Although the cost of MG500 alloy and refining increases, due to the higher selling price, the profit per ton of steel increases by about 90 yuan. In some periods of 2023, 4,879 tons were produced, generating an efficiency of 440,000 yuan. With the expansion of the market and the growth of production, the benefits continue to rise. At the same time, stable production reduces waste and rework, lowers production costs, and improves resource utilization and enterprise efficiency.

[0048] Furthermore, this process enhances market competitiveness: Successfully developing MG500 bolt steel enriches the product variety, meets the high-end needs of the coal industry, improves the enterprise's popularity and influence in the bolt steel market, attracts more customer orders, expands the market share, consolidates the enterprise's position in the industry, lays a solid foundation for long-term development, helps the enterprise stand out in the fierce market competition, and achieves sustainable development.

[0049] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation process for the smelting of anchor rod steel bars, comprising the following process steps: S1 molten iron preparation, S2 converter smelting, S3 LF refining, S4 continuous casting, and S5 rolling, characterized in that: The S1 molten iron preparation: ensure that the quality of the molten iron meets the smelting requirements, provide a basis for subsequent reactions, and its composition and temperature indicators must be stable; S2 converter smelting; End point control: strictly control the converter tapping temperature at 1591-1665℃, C content at 0.08-0.15%, Mn content at 0.07-0.14%, P content at 0.011-0.021%, S content at 0.019-0.023%; During the steel-making process, only ferrosilicon and silicon-manganese are deoxidized and alloyed, and lime and fluorite are added as top slag materials. Fluorite is added first and then lime. The amount of lime added is 1kg / ton and fluorite is 20kg / furnace. Accurate endpoint control can ensure that the composition of molten steel meets the requirements of MG500, laying the foundation for subsequent refining. S3LF refining; Parameter control: The temperature rises slowly during the refining process. The amount of lime added is 2 kg per ton of steel. The power-on time is 20 minutes. The entire refining cycle is 35 minutes. Reasonable refining parameters can effectively remove impurities in molten steel, further adjust the composition, and improve the purity of molten steel. Composition adjustment: According to the MG500 internal control standard, the composition of molten steel is accurately adjusted, and the composition is ensured to be stable by adding appropriate alloys to meet the performance requirements of anchor steel; S4 continuous casting; Mold protection slag: HRB400E protection slag is used and fully baked before use to ensure its stable performance, effectively prevent molten steel oxidation and mold wall adhesion, and ensure the surface quality of the ingot; Secondary cooling water distribution: water distribution is carried out at 1.9-2.0L / kg, the water volume of the crystallizer is 135t / h, the water flow of the foot roll is 21.3t / h, the first stage is 20.5t / h, the second stage is 9t / h, and the third stage is 3t / h (pulling speed is 2.55m / min). Reasonable cooling water volume can make the billet cool evenly, avoid the generation of internal cracks, and ensure the dense internal structure of the billet; Casting speed and electromagnetic stirring: The casting speed is controlled at 2.3-2.6m / min, the water temperature difference of the crystallizer is 5-7℃, and electromagnetic stirring is applied to the crystallizer at the same time, with a current of 240A, a voltage of 150V, and a frequency of 4.0HZ. The continuous stirring mode is adopted. Appropriate casting speed and electromagnetic stirring can improve the solidification structure of the ingot and reduce segregation and defects. Tundish temperature control: MG500 liquidus is calculated as 1503℃.

2. The preparation process for the anchor rod steel bars used in smelting according to claim 1, wherein: The S2 converter smelting process operation: During the steelmaking process, close attention should be paid to the reaction of the molten steel to ensure the deoxidation and alloying effect, stabilize the composition and temperature of the molten steel, and prevent the composition deviation from affecting the performance of the steel.

3. The preparation process for the anchor rod steel bar smelting according to claim 1, characterized in that: The temperature of the tundish is controlled at 1519-1555°C, with an average of 1531°C and a superheat of 28°C. The stable temperature of the tundish helps to stabilize the quality of the ingot and prevent defects caused by temperature fluctuations.

4. A preparation process for the smelting of anchor rod steel bars according to claim 1, characterized in that: The parameter control: the composition of the refined slag sample is controlled within a specific range, such as Al2O3 2.03%, CaO 56.45%, MnO 0.29%, MgO 7.35%, SiO2 25.50%, TFe 1.64%, R 2.21%, and the fixed oxygen content is 19ppm, basically achieving white slag steelmaking.

5. A preparation process for the anchor rod steel bar smelting according to claim 1, characterized in that: The composition adjustment: According to the internal control standard of MG500, accurately adjust the composition of molten steel. For example, the C content is controlled at 0.23 - 0.27%, the Si content at 0.40 - 0.55%, the Mn content at 1.40 - 1.57%, the P content ≤ 0.035%, the S content ≤ 0.035%, and the V content ≥ 0.050%. By adding suitable alloys, ensure the stability of the composition and meet the performance requirements of anchor steel.