HG6EC high-performance bar rolling method

Abstract

The invention relates to the technical field of ferrous metallurgy, and particularly discloses an HG6EC high-performance bar rolling method which comprises the following steps: S1, temperature control: the tapping and rolling temperature of a steel billet, the temperature control range of a preheating section, a heating section and a soaking section and the heating and heat preservation time; s2, rolling parameter optimization: controlling rolling hole pattern design, loop parameters and in-furnace time control; the size, the appearance, the weight and the allowable deviation of the steel meet the standard requirements, the included angle beta between the transverse ribs and the axis of the steel bar is controlled to be 45-70 degrees, and the directions of the transverse ribs on the two opposite faces of the steel bar are opposite; the angle alpha is not less than 45 degrees; s4, performance requirements including tensile strength, lower yield strength, ductility, impact performance and bending performance control; through reasonable alloy element ratio, heating schedule, heating speed and innovative rolling process, the ductility of the steel bar is ensured, and the steel bar has good plasticity, high-efficiency cost reduction and outstanding energy conservation and emission reduction.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, specifically to a method for rolling HG6EC high-performance bars. Background Technology

[0002] Traditional steel bar manufacturing processes have numerous limitations in meeting the construction industry's demands for high strength, high toughness, and corrosion resistance. Their broad raw material selection fails to precisely consider the impact of impurities and subtle differences in composition on steel performance, leading to fluctuations in basic quality. In the smelting stage, outdated equipment and processes result in inaccurate temperature and time control, rudimentary furnace atmosphere management, incomplete impurity removal, and poor steel purity, hindering subsequent performance improvements. During rolling, conservative material design fails to dynamically optimize based on metal properties and finished product requirements, and rudimentary mill parameter control results in products that cannot achieve high precision and performance standards. Heat treatment is simplistic and arbitrary, with improper settings for cooling rates, holding times, and slow cooling stages, failing to accurately shape ideal metallographic structures and microstructures, severely weakening the steel's overall performance and making it difficult to meet the stringent requirements of large and complex construction projects. Therefore, innovation in the manufacturing process of high-performance HG6EC steel bars is urgently needed.

[0003] Traditional steel bar rolling has the following problems:

[0004] 1. Performance limitations.

[0005] Insufficient strength: The strength of steel bars produced by traditional processes cannot meet the stringent requirements for load-bearing capacity of large bridges and super high-rise buildings. In complex stress environments, they are prone to structural deformation, cracks, and even collapse, threatening the safety and lifespan of buildings.

[0006] Poor toughness: In earthquake and impact resistance scenarios, due to its lack of toughness, it cannot effectively absorb and disperse energy, making it prone to brittle fracture, which damages the stability of the building, increases maintenance costs and safety hazards.

[0007] Poor corrosion resistance: In humid and corrosive environments, the lack of effective protection mechanisms leads to steel corrosion causing volume expansion and concrete spalling, which weakens the structural load-bearing capacity, reduces the service life of buildings, and increases maintenance and reconstruction costs.

[0008] 2. The process is crude.

[0009] Lack of smelting precision: Steelmaking equipment is inefficient and the process is rudimentary. Temperature, time and furnace atmosphere are poorly regulated, deoxidation and desulfurization are insufficient, impurities remain, and the uniformity and purity of molten steel are low. This results in uneven microstructure and numerous defects in the steel, limiting the space for performance optimization.

[0010] Inaccurate rolling parameters: Rigid material shape design without optimization based on metal properties; poor coordination of parameters such as mill reduction, elongation, bite torque, and looper tension; resulting in low product dimensional accuracy, poor surface quality, and insufficient performance consistency, failing to meet the high precision and high performance requirements of high-end construction steel.

[0011] Therefore, there is an urgent need to design a rolling method for HG6EC high-performance bars to solve the problems of high production cost and poor plasticity of existing high-performance HG6EC bars. Summary of the Invention

[0012] To address the problems existing in the prior art, the purpose of this invention is to provide a method for rolling HG6EC high-performance bars.

[0013] The technical solution adopted by this invention to solve its technical problem is: a method for rolling HG6EC high-performance bars, comprising the following steps:

[0014] S1. Temperature control: the billet's exit temperature before rolling, the temperature control range of the preheating section, heating section and soaking section, and the heating and holding time;

[0015] S2. Rolling parameter optimization: control the roll pass design, looper parameters and furnace time control;

[0016] S3. Dimensional requirements: The dimensions, shape, weight, and allowable deviations of the steel shall meet the standard requirements: the angle β between the transverse rib and the axis of the steel bar shall be controlled between 45° and 70°, and the directions of the transverse ribs on opposite sides of the steel bar shall be opposite; the angle α shall not be less than 45°.

[0017] S4. Performance requirements: including tensile strength, lower yield strength, ductility, impact performance, and bending performance control.

[0018] Specifically, in step S1, the initial rolling temperature is controlled at 1150-1165℃, the preheating zone temperature is 650-700℃, the heating zone heating rate is 150-170℃ / h, the soaking zone temperature is 1275±20℃, and the heating and holding time is 3-3.5 hours.

[0019] Specifically, in step S2, the rolling pass design enlarges the roughing and intermediate rolling pass by 1-1.5mm based on the original size, the pre-finishing rolling pass by 0.5-1mm, and the finishing rolling pass by 0.2-0.5mm, according to different steel grades; the biting torque is set to be greater than the idle torque, and the throwing torque is set to be less than the strip torque.

[0020] Specifically, in step S2, the height of the looper is increased by 3-8mm based on the original size of the steel grade; the rolling rhythm cannot be rolled at full load head to tail, but is controlled by a rolling rhythm of one billet per minute to ensure that the furnace time of each billet is controlled at 110-130 minutes.

[0021] Specifically, in step S3, the total gap between the ends of the transverse ribs on two adjacent surfaces of the reinforcing bar should not exceed 20% of the nominal perimeter of the reinforcing bar, and the gap between the ends of the transverse ribs on two adjacent surfaces of the reinforcing bar includes the width of the longitudinal ribs.

[0022] Specifically, in step S4, the tensile strength is ≥820MPa, the lower yield strength is ≥650MPa, the ductility is expressed as the total elongation at maximum force ≥9.0%, the impact performance is expressed as the strength-to-yield ratio ≥1.25, and the bending performance is expressed as the yield-to-yield ratio ≤1.30.

[0023] The present invention has the following beneficial effects:

[0024] The HG6EC high-performance bar rolling method designed in this invention promotes the production of HG6EC high-strength steel bars through reasonable alloy element ratios, heating regimes, heating rates, and innovative rolling processes. It simultaneously ensures the elongation of the steel bars, yield strength ≥650 MPa, tensile strength ≥820 MPa, maximum total elongation ≥9.0%, and good plasticity. The method establishes and improves the process standards for high-strength steel bars and the influence of high-temperature steel on the rolling torque. It achieves significant cost reduction, energy conservation, and emission reduction. Optimized processes at the production end reduce mill energy consumption, contributing to the green transformation of the steel industry and promoting the sustainable upgrading of the construction industry. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be described clearly, completely, and in further detail below. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] The purpose of this invention is to provide a rolling method for HG6EC high-performance bars. Through reasonable alloy element ratios, heating regimes, heating rates, and innovative rolling processes, this method promotes the production of HG6EC high-strength steel bars while ensuring the elongation, yield strength ≥650 MPa, tensile strength ≥820 MPa, maximum total elongation ≥9.0%, and good plasticity. A complete set of process data for high-strength steel bar production, from heating to rolling, has been developed, and comprehensive process standards for high-strength steel bars have been established, along with the influence of high-temperature steel on the rolling torque. This method overcomes the technical challenge of ensuring plasticity while pursuing strength in traditional high-strength steel bars. A comprehensive HG6EC process standard has been established, providing a reference for other companies in the industry and laying the foundation for the next step of developing new high-strength steel varieties, thus promoting technological progress throughout the industry.

[0027] Example 1.

[0028] A method for rolling HG6EC high-performance bars includes the following steps:

[0029] 1. Temperature Control: The initial rolling temperature of the steel billet, the temperature range of the preheating section, heating section, and soaking section, and the heating and holding time; the initial rolling temperature is controlled at 1150-1165℃, the preheating section temperature at 650-700℃, the heating rate in the heating section at 150-170℃ / h, the soaking section temperature at 1275±20℃, and the heating and holding time at 3-3.5 hours. This ensures the metallographic structure of the reinforcing steel and guarantees the maximum total elongation.

[0030] 2. Rolling Parameter Optimization: Control the roll pass design, looper parameters, and furnace time control; in accordance with the high-strength steel bar standard requirements, and specifically for the high-temperature rolling requirements of HG6EC high-strength steel, fully consider the metal's plasticity and deformation resistance, as well as changes in phase and grain size, and study the roll pass design, rolling speed, rolling rhythm, elongation parameters, bite torque, stand reduction, and looper parameters; currently, due to the rolling temperature being 150℃ higher than that of ordinary HRB400E steel, the mill bounce is smaller, the torque is lower, and the looper is slightly stretched. The roll pass design is based on different steel grades, with the roughing and intermediate rolling pass enlarged by 1-1.5mm, the pre-finishing roll enlarged by 0.5-1mm, and the finishing roll enlarged by 0.2-0.5mm; the bite torque and strip throwing torque are adjusted accordingly based on different stands. In principle, the bite torque should be greater than the idle torque, and the strip throwing torque should be less than the strip torque. The height of the looper is increased by 3-8mm based on the original size of the steel grade; the rolling rhythm cannot be rolled at full load head and tail, but the steel is tapped at a rhythm of one billet per minute to ensure that the time of each steel billet in the furnace is controlled at 110-130 minutes to ensure stable performance.

[0031] 3. Dimensional requirements: The dimensions, shape, weight, and allowable deviations of the steel shall comply with the requirements of GB1499.2-2024 standard: the angle β between the transverse rib and the axis of the steel bar shall be controlled between 45° and 70°, and the directions of the transverse ribs on opposite sides of the steel bar shall be opposite; the angle α shall not be less than 45°; the total gap between the ends of the transverse ribs on two adjacent sides of the steel bar shall not be greater than 20% of the nominal circumference of the steel bar, and the gap between the ends of the transverse ribs on two adjacent sides of the steel bar includes the width of the longitudinal rib.

[0032] 4. Performance Requirements: These include control over tensile strength, lower yield strength, ductility, impact performance, and bending performance. Tensile strength ≥ 820 MPa, lower yield strength ≥ 650 MPa, ductility is expressed as total elongation at maximum force ≥ 9.0%, impact performance is expressed as strength-to-yield ratio ≥ 1.25, and bending performance is expressed as yield-to-yield ratio ≤ 1.30. A comparison of specific control targets and standard values ​​for the mechanical properties of HG6EC steel is shown in Table 1.

[0033] Table 1 Comparison of Mechanical Properties of HG6EC Steel

[0034] Lower yield strength MPa Tensile strength (MPa) Maximum total elongation % Strength-to-weight ratio Crescent standard ≥635 ≥800 ≥9.0 ≥1.25 ≤1.30 Control Target ≥650 ≥820 ≥9.0 ≥1.25 ≤1.30

[0035] 5. Steel cooling: During the rolling and cooling process of high-strength steel bars, the grains of the steel are refined and the grain boundaries increase. Although this increases the strength of the steel, it reduces the plasticity of the material. Research is needed on the cooling and collection of high-strength high-temperature rolled steel.

[0036] This invention employs an innovative heating regime and hot rolling process, solving the problem of unreliable material dimensions and performance in traditional processes. This ensures that the dimensions and performance of HG6EC steel bars meet standard requirements, successfully developing high-strength steel bars with a strength level of 635 MPa, while maintaining high plasticity and seismic resistance. Through rational alloy element design and proportioning, combined with innovative hot rolling and steel cooling processes, the microstructure of the steel is adjusted and optimized, improving its strength, toughness, and corrosion resistance. During rolling, strict control of the stand material shape and tension adjustment, among other new processes, ensures the dimensional accuracy and surface quality of the steel bars, while also guaranteeing the continuity and stability of the product manufacturing process. The billet is in the furnace for more than 90 minutes. This furnace time is used to ensure the initial rolling temperature, which is controlled according to the centerline as the target value, and the first shear temperature is kept as close to the beginning and end as possible. During rolling line production, the spray water, cooling water, and fans are strictly controlled to reduce water penetration or rapid cooling of the rolled pieces during rolling, avoiding the formation of abnormal metallographic structures. The rolling process is maintained in a slightly stretched state.

[0037] The products manufactured by this invention achieve significant cost reductions in practical applications: In engineering projects, the high strength reduces steel reinforcement usage by 15%, lowering material procurement costs; improved durability shortens maintenance cycles and reduces maintenance intensity, resulting in long-term lower operating costs. Energy conservation and emission reduction are also prominent: On the production side, optimized processes reduce rolling mill energy consumption, saving over 10.755 kWh per ton of steel; during the service life, the robust and durable construction reduces construction and maintenance material and energy consumption, as well as waste emissions, saving 50,700 tons of standard coal and reducing carbon dioxide emissions by 124,500 tons per 10,000 tons of HG6EC steel, aligning with low-carbon development, aiding the green transformation of the steel industry, and promoting the sustainable upgrading of the construction industry.

[0038] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0039] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A method for rolling HG6EC high-performance bars, characterized in that, Includes the following steps: S1. Temperature control: the billet's exit temperature before rolling, the temperature control range of the preheating section, heating section and soaking section, and the heating and holding time; S2. Rolling parameter optimization: control the roll pass design, looper parameters and furnace time control; S3. Dimensional requirements: The dimensions, shape, weight, and allowable deviations of the steel shall meet the standard requirements: the angle β between the transverse rib and the axis of the steel bar shall be controlled between 45° and 70°, and the directions of the transverse ribs on opposite sides of the steel bar shall be opposite; the angle α shall not be less than 45°. S4. Performance requirements: including tensile strength, lower yield strength, ductility, impact performance, and bending performance control.

2. The method for rolling HG6EC high-performance bars according to claim 1, characterized in that, In step S1, the initial rolling temperature is controlled at 1150-1165℃, the preheating zone temperature is 650-700℃, the heating zone heating rate is 150-170℃ / h, the soaking zone temperature is 1275±20℃, and the heating and holding time is 3-3.5 hours.

3. The method for rolling HG6EC high-performance bars according to claim 1, characterized in that, In step S2, the rolling pass design enlarges the roughing and intermediate rolling pass by 1-1.5mm based on the original size, the pre-finishing rolling pass by 0.5-1mm, and the finishing rolling pass by 0.2-0.5mm, according to different steel grades; the biting torque is set to be greater than the idle torque, and the throwing torque is set to be less than the strip torque.

4. The method for rolling HG6EC high-performance bars according to claim 1, characterized in that, In step S2, the height of the looper is increased by 3-8mm based on the original height, depending on the steel grade and size. The rolling rhythm cannot be rolled at full load from top to bottom. Instead, the steel billet is tapped at a rate of one billet per minute to ensure that the furnace time for each billet is controlled at 110-130 minutes.

5. The method for rolling HG6EC high-performance bars according to claim 1, characterized in that, In step S3, the total gap between the ends of the transverse ribs on two adjacent surfaces of the reinforcing bar should not exceed 20% of the nominal perimeter of the reinforcing bar. The gap between the ends of the transverse ribs on two adjacent surfaces of the reinforcing bar includes the width of the longitudinal ribs.

6. The method for rolling HG6EC high-performance bars according to claim 1, characterized in that, In step S4, the tensile strength is ≥820MPa, the lower yield strength is ≥650MPa, the ductility is expressed as the total elongation at maximum force ≥9.0%, the impact performance is expressed as the strength-to-yield ratio ≥1.25, and the bending performance is expressed as the yield-to-yield ratio ≤1.30.