LU102372B1 - 600MPA CLASS STEEL ROD FOR REINFORCED CONCRETE AND MANUFACTURING METHODS FOR IT - Google Patents

Abstract

The present invention provides a 600MPa grade steel rod for reinforced concrete and a manufacturing method for refining a raw material for manufacturing steel through a converter to obtain a coarsely refined molten steel; Refining the coarsely refined molten steel by a refining furnace to obtain a refined molten steel; Rolling through a continuous caster to obtain a continuously cast steel billet; Transferring to a heating furnace for heating and then feeding the heated steel billets to a stand roughing mill for roughing to obtain a roughed steel billet; after shearing and breaking, they are fed to a stand intermediate rolling mill for an intermediate rolling process, subjecting the steel billet to a pre-water cooling section for finish rolling at low temperature and then shearing and breaking, and feeding the steel billet to a stand finishing rolling mill for finish rolling, cooling and shearing of the finish-rolled steel billet and subsequent finishing and storage. It is difficult to meet the strength requirement based on a single production process, resulting in a problem of high cost. Adjustment of chemical components and rolling process on the basis of ordinary steel bars is realized, thereby meeting the requirements for various indicators of high-performance steel bars, thereby achieving stable industrialized rolling technology to achieve the technical effect of reducing cost and improving utility .

Description

.. LU102372 600MPA CLASS STEEL ROD FOR REINFORCED CONCRETE AND

MANUFACTURING PROCESS FOR IT

TECHNICAL FIELD The present invention relates to the technical field of manufacturing methods for the steel rod, in particular a steel rod of 600MPa class for reinforced concrete and a manufacturing method therefor.

BACKGROUND ART Currently, the market for HRB400 (E) and HRB500 (E) steel rods is saturated, which will not be improved in the short term, but there is a need in the market for high strength antiseismic steel rods of 600 MPa or higher class. The 600 MPa grade high strength steel bars are currently the highest grade steel bars in China and are widely used in various building structures, especially large, heavy, light thin-walled and tall buildings. Compared to steel rods of the 400 MPa class, the use of high-strength steel rods of the 600 MPa class or a higher class can save at least 30% of the steel consumption. In addition, the development and use of such high-strength steel bars will also promote the diffusion and use of new high-performance, energy-saving and environmentally friendly materials, greatly improve the variety structure of current products for buildings, and provide strong support for the realization of resource-efficient and environmentally friendly enterprises.

However, the applicant of the present invention has found that the prior art has at least the following technical problem: in the prior art, the micro-alloy route is selected and it is difficult to meet the strength requirements based on a single production process, resulting in a problem with high costs.

SUMMARY OF THE PRESENT INVENTION The embodiment of the present invention provides a 600MPa grade steel bar for reinforced concrete and a manufacturing method therefor to solve the problem in the prior art that the micro-alloy route is selected so that it is difficult to obtain in a single one Production process based on meeting the strength requirements, which leads to high costs.

In view of the above problems, the embodiment of the present application provides a steel bar of 600MPa class for reinforced concrete and a manufacturing method therefor.

According to a first aspect, the present invention provides a method of manufacturing the steel bar of the 600MPa class for reinforced concrete, the method comprising: refining a raw material for manufacturing steel by a converter to obtain a coarsely refined molten steel; Refining the coarsely refined molten steel by a refining furnace to obtain a refined molten steel; Rolling the refined molten steel through a continuous caster to obtain a continuously cast steel billet; Transferring the continuously cast steel billets to a heating furnace for heating and then feeding the heated steel billets to a stand roughing mill for roughing to obtain a roughed steel billet; after the pre-rolled steel billets are sheared and broken, they are fed to a stand intermediate rolling mill for intermediate rolling to obtain an intermediate rolled steel billet; Subjecting the intermediate-rolled steel billet to a pre-water cooling section for finish-rolling at a low temperature, followed by shearing and breaking, and feeding the steel billet to a stand finish-rolling mill for finish-rolling to obtain a finish-rolled steel billet; Cooling and shearing of the finished rolled steel billet and then finishing and storage.

Preferably, prior to conveying the continuously cast steel billet to the heating furnace for heating, the method comprises: inspecting the continuously cast steel billet; and conveying the continuous cast steel billet which passes the inspection by means of a conveyor roller bed into the heating furnace for heating.

Preferably, the shearing and breaking of the pre-rolled steel billet comprises: shearing a steel billet head and a steel billet tail of the pre-rolled steel billet by crank shear and then breaking.

Preferably, subjecting the intermediate rolled steel billet to a pre-water cooling section for finish rolling at low temperature and then shearing and breaking comprises: shearing a steel billet head and a steel billet tail of the finish rolled steel billet by rotary shearing and then breaking.

Preferably, the cooling and shearing of the finish-rolled steel billet and subsequent finishing and storage comprise: subjecting the finish-rolled steel billet to a water cooling section for controlled cooling; Performing segmented shear on the cooled finish rolled steel billet using multiple length shear; After natural cooling in a cooling bed, the sheared, finish-rolled steel billet is sheared to a fixed length with cold shears; and finishing and storing the steel billet obtained after shearing. Preferably, the finishing and storage of the steel billet obtained after shearing comprise the following: sorting out an undersized steel billet from the steel billets obtained; Counting and finishing the remaining steel billets after the under-sized steel billets have been sorted out; Bundling and weighing of the finished steel billets, and storing by lifting and conveying.

A temperature control section is preferably arranged between the respective rolling mills, while no return section is required.

Preferably the V / N ratio in the raw material for making steel is 3.49-3.83. Preferably, the main component of the nitrogen booster in the raw material for making steel is ferrosilicon nitride.

Preferably, the main component of the nitrogen booster in the raw material for producing steel is silicon manganese nitride.

The main component of the nitrogen booster in the raw material for producing steel is preferably the ferromanganese nitride.

Preferably, the percentage of Nb in the raw material for making steel is 0.015-0.025%. According to a second aspect, the present invention provides a steel bar of the class 600MPa for reinforced concrete which is suitable for the above-described manufacturing process, the steel bar of the class 600MPa for reinforced concrete having the following components in the following percentages: C: 0 , 21-0.26%; Mn: 1.40-1.80%; Si: 0.65-0.84%; V: 0.08-0.11%; S <0.020% :; P <0.025%; N: 0.023-0.029%; Nb: 0.015-0.025%; the balance being Fe and inevitable impurities.

Preferably, the V / N ratio in the percentage of the steel rod of the class 600MPa for reinforced concrete is not greater than 5. Preferably, the V / N ratio in the percentage of the steel rod of the class 600MPa for reinforced concrete is 3.49-3 , 83.

Preferably, the grains in the steel bar of the 600MPa class for reinforced concrete are no larger than 4 µm.

Preferably, the strength of the steel rod of the 600MPa class for reinforced concrete is 600 MPa.

Preferably, the main component of the nitrogen booster in the steel rod of the 600MPa class for reinforced concrete is ferrosilicon nitride.

Preferably, the main component of the nitrogen booster in the steel rod of the 600MPa class for reinforced concrete is silicon manganese nitride.

Preferably, the main component of the nitrogen booster in the steel rod of the 600MPa class for reinforced concrete is the ferro-manganese nitride.

The above one or more technical solutions in the embodiments of the present application have at least one or more of the following technical effects:

1. An embodiment of the present invention provides a method of manufacturing the steel bar of the 600MPa class for reinforced concrete, the method comprising: refining a raw material for making steel by a converter to obtain a coarsely refined molten steel; Refining the coarsely refined molten steel by a refining furnace to obtain a refined molten steel; Rolling the refined molten steel through a continuous caster to obtain a continuously cast steel billet; Transferring the continuously cast steel billets to a heating furnace for heating and then feeding the heated steel billets to a stand roughing mill for roughing to obtain a roughed steel billet; after the pre-rolled steel billets are sheared and broken, they are fed to a stand intermediate rolling mill for intermediate rolling to obtain an intermediate rolled steel billet; Subjecting the intermediate-rolled steel billet to a pre-water cooling section for finish-rolling at a low temperature followed by shearing and breaking, and feeding the steel billet to a stand finish-rolling mill for finish-rolling to obtain a finish-rolled steel billet; Cooling and shearing of the finished rolled steel billet and subsequent finishing and storage. The adjustment of the chemical components and the rolling process on the basis of the ordinary steel rods is realized, thereby improving the overall performance of steel rods that meet the requirements for various indicators of the high-performance steel rods from class 600 MPa after quenching and tempering, thereby making a steelmaking and continuous casting technology for high micro-alloy steel billets designed to avoid surface defects of casting billets, and the solid solution reinforcement, fine grain reinforcement, precipitation reinforcement of micro-alloy and the corresponding heating technology, controlled rolling technology / controlled cooling rolling technology are combined to form a stable industrial rolling technology, thus creating the technical effects of cost reduction and significant improvement in profitability can be achieved. This solves the problem in the prior art that the micro-alloy route is selected so that it is difficult to meet the strength requirement based on a single production process, resulting in high cost.

2. An embodiment of the present invention provides a steel bar of the class 600MPa for reinforced concrete, the steel bar of the class 600MPa for reinforced concrete having the following components in the following percentages: C: 21-26%; Mn: 1.40-1.80%; Si: 0.65-0.84%; V: 0.08-0.11%; S <0.020%; P <0.025%; N: 0.023-0.029%; Nb: 0.015-0.025%; the balance being Fe and inevitable impurities. An Nb and V composite component system is achieved which has been specially developed to meet the requirements for steel rods of 600 MPa in terms of fine grain, high strength and anti-seismicity. By adjusting the process and composition, the rolled steel bar can meet the usage requirement for a high strength of 600 MPa, and at least 30% of the steel consumption is saved, thereby greatly improving the grade structure of the current building products and the economy. This solves the problem in the prior art that the micro-alloy route is selected so that it is difficult to meet the strength requirement based on a single production process, resulting in high cost.

The above explanation is only an extrapolation of the technical solution of the present invention. In conjunction with the content of the description, the present invention can be implemented in order that the technical measures of the present invention can be more clearly understood, and the following are the detailed embodiments of the present invention In order for the above and other objects, features, and advantages of the present invention to be more apparent and readily understood, the invention will be further described.

BRIEF DESCRIPTION OF THE DRAWING Figure 1 shows a schematic flow diagram of a method for manufacturing the 600MPa class steel bar for reinforced concrete in an embodiment of the present invention.

DETAILED DESCRIPTION The embodiment of the present invention provides a 600MPa grade steel bar for reinforced concrete and a manufacturing method therefor to solve the problem in the prior art that the micro-alloy route is selected to be difficult based on a single production process to meet the strength requirements, which leads to high costs. The general idea of the technical solutions of the present invention is as follows: refining a raw material for making steel by a converter to obtain a coarsely refined molten steel; Refining the coarsely refined molten steel by a refining furnace to obtain a refined molten steel; Rolling the refined molten steel through a continuous caster to obtain a continuously cast steel billet; Transferring the continuously cast steel billets to a heating furnace for heating and then feeding the heated steel billets to a stand roughing mill for roughing to obtain a roughed steel billet; after the pre-rolled steel billets are sheared and broken, they are fed to a stand intermediate rolling mill for intermediate rolling to obtain an intermediate rolled steel billet; Subjecting the intermediate-rolled steel billet to a pre-water cooling section for finish-rolling at a low temperature, followed by shearing and breaking, and feeding the steel billet to a stand finish-rolling mill for finish-rolling to obtain a finish-rolled steel billet; Cooling and shearing of the finished rolled steel billet and then finishing and storage. The adjustment of the chemical components and the rolling process on the basis of the ordinary steel rods is realized, thereby improving the overall performance of steel rods that meet the requirements for various indicators of the high-performance steel rods from the class 600 MPa after quenching and tempering, thereby making a steelmaking process. and continuous casting technology for highly microalloyed steel billets to avoid surface defects of cast billets, and the solid solution reinforcement, fine grain reinforcement, precipitation reinforcement of microalloy and the corresponding heating technology, controlled rolling technology / controlled cooling rolling technology are combined to form stable industrial rolling technology, thereby combining the technical Effects of oT cost reduction and the significant improvement in profitability can be achieved.

It will be understood that in the embodiment of the present invention LF (LADLE FURNACE) is the abbreviation for ladle furnace, i.

Ladle refining furnace, which is the main refining equipment outside the furnace in steelmaking.

The LF furnace generally refers to the refining furnace in the steel industry.

In fact, it is a special form of the electric arc furnace.

The refining of the LF furnace is mainly based on the white slag in the cylinder, whereby argon is blown into the cylinder for stirring in a low-oxygen atmosphere (where the oxygen content is 5%) and the molten steel passing through the primary furnace is heated with graphite electrodes to produce a Realize refining.

Since stirring with argon accelerates the chemical reaction between slag and steel, and the use of arc heating for temperature compensation can ensure a long refining time, the oxygen and sulfur content in the steel can be reduced with the inclusion rating according to ASTM 0-0.1.

The LF furnace can be used in combination with an electric furnace to replace the reduction time of the electric furnace, and can also be used in combination with an oxygen converter to make high quality alloy steel.

In addition, the LF furnace is also an indispensable piece of equipment for controlling the composition and temperature and storing the molten steel in a continuous casting workshop, especially a production line for continuous casting of alloy steel.

The advent of the LF furnace therefore leads to the formation of a new joint production line of LD-LF-RH-CC (continuous casting) for the production of quality steel.

The reduction refining of steel on such a common production line is mainly based on the LF furnace.

The LF furnace can process steel of almost all types, from special steel to ordinary steel.

Depending on the quality control requirements, different process operating systems can be used in production.

Among various secondary refineries, the LF furnace has a high, comprehensive price / performance ratio.

In connection with figures in the embodiments of the present invention, the technical solution in the embodiments of the present invention will hereinafter be explained clearly and completely, so that the object, the technical solutions and the advantages of the present invention will become clearer.

Obviously, the described embodiments do not represent all embodiments, but only a part of the embodiments of the present invention.

All other embodiments obtained by those skilled in the art based on the embodiments in the present invention without creative work are to be considered to be included within the scope of the present invention.

Embodiment 1 FIG. 1 shows a schematic flow diagram of a method for manufacturing the steel bar of the 600MPa class for reinforced concrete in an embodiment of the present invention.

As shown in Figure 1, an embodiment of the present invention provides a method of manufacturing the steel bar of the 600MPa class for reinforced concrete, the method comprising: Step 10: Refining a raw material for making steel by a converter to a coarse to obtain refined molten steel.

Step 20: Refining the coarsely refined molten steel by a refining furnace to obtain a refined molten steel.

Step 30: Rolling the refined molten steel through a continuous caster to obtain a continuously cast steel billet.

Step 40: Transferring the continuously cast steel billets to a heating furnace for heating and then feeding the heated steel billets to a stand roughing mill for roughing to obtain a roughed steel billet.

Preferably, prior to conveying the continuously cast steel billet to the heating furnace for heating, the method comprises: inspecting the continuously cast steel billet; and conveying the continuous cast steel billet that passes the check by means of a conveyor roller bed into the heating furnace for heating.

Step 50: after the pre-rolled steel billets are sheared and broken, they are fed to a stand intermediate rolling mill for intermediate rolling to obtain an intermediate rolled steel billet.

Preferably, the shearing and breaking of the pre-rolled steel billet comprise the following: shearing a steel billet head and a steel billet tail of the pre-rolled steel billet by crank shear and subsequent breaking.

Step 60: subjecting the intermediate-rolled steel billet to a pre-water cooling section for finish rolling at a low temperature, followed by shearing and breaking, and feeding the steel billet to a stand finishing mill for finish rolling to obtain a finish-rolled steel billet.

Preferably, subjecting the intermediate-rolled steel billet to a pre-water cooling section for finish-rolling at low temperature and then shearing and breaking comprises: shearing a steel billet head and a steel billet tail of the finish-rolled steel billet by rotary shearing and then breaking.

Step 70: cooling and shearing of the finish-rolled steel billet and subsequent finishing and storage.

In the existing HRB400 and HRB500 products in particular, the content of common alloying elements such as C, Si, Mn etc. is already close to the upper limits specified in the Chinese industrial standard GB 1499.2.

There is not much room for increasing the C, Si and Mn content during the development of HRB600. Good weldability is a basic requirement for the universal use of the products.

To ensure processing and welding performance, China's national standards also set clear requirements for microstructure and carbon equivalent.

On the basis of this, the route of the micro-alloying should be selected, and the fine-grain reinforcement used is based on the special process of controlled post-rolling cooling to refine the grains.

However, the actual situation is often much more complicated, making it quite difficult to rely on a single production process for the grains to reach 4 µm or less; in addition, the cost of the V alloy is relatively high and a high alloy content is likely to lead to abnormal microstructures.

In order to avoid the above factors, the embodiment of the present invention uses the alloy process to produce high-strength steel bars of the 600 MPa class by the same production process as the current low and medium strength steel bars, on the one hand, the modification of the production line as well as the resulting Modification of a number of equipment and cost increases can be avoided; on the other hand, it is conducive to the rapid production and distribution of new products on a large scale.

The production equipment is modified according to the technical requirements of the whole process of continuous temperature controlled rolling, and the technical way of the processing process of the embodiment of the present invention is: transition 4-5 # converter - LF refining furnace - 4- S # continuous casting machine - steel billet inspection - heating with Heating furnace - 8-column pre-rolling plant - Shearing of head and tail by crank shearing and breaking - 4-column intermediate rolling plant - Pre-water cooling section for finish rolling at low temperature - Shearing of head and tail by rotary shearing and breaking - 6-

Column finishing mill - controlled cooling in a re-rolling - water cooling section - segmented shearing with a shear with several lengths - natural cooling in a cooling bed - shearing with a cold shear with fixed length - sorting out an undersized steel billet - counting and finishing - bundling and weighing - lifting and Conveying and storing.

According to the actual production equipment parameters of the roughing, intermediate and finishing mill in the steel bar rolling production line, and making extensive use of the process measures such as recrystallization, non-recrystallization and deformation-induced ferrite transformation and controlled cooling after rolling, the control of the growth of grains and the homogenization of microstructures are achieved.

At the same time, the process path is optimized, which is mainly based on alloying with the help of the rolling process, thereby reducing product production costs and achieving stable product quality, as the product manufacturing technology matures, companies have the ability to continue innovating with minimal technical risks.

This solves the problem in the prior art that the micro-alloy route is selected so that it is difficult to meet the strength requirement based on a single production process, resulting in high cost.

The adjustment of the chemical components and the rolling process on the basis of the ordinary steel rods is realized, thereby improving the overall performance of steel rods that meet the requirements for various indicators of the high-performance steel rods from class 600 MPa after quenching and tempering, thereby making a steelmaking and continuous casting technology for high micro-alloy steel billets to avoid surface defects of casting billets, and the solid solution reinforcement, fine grain reinforcement, precipitation reinforcement of micro-alloy and the corresponding heating technology, controlled rolling technology / controlled cooling rolling technology are combined to form a stable industrial rolling technology, thereby the technical Effect of significant improvement in economy is achieved.

Preferably, cooling and shearing the finish-rolled steel billet and then finishing and storing include: subjecting the finish-rolled steel billet to a water cooling section for controlled cooling; Performing segmented shear on the cooled finish rolled steel billet using multiple length shear; After natural cooling in a cooling bed, the sheared, finish-rolled steel billet is sheared to a fixed length with cold shears; and finishing and storing the steel billet obtained after shearing. Preferably, finishing and storing the steel billet obtained after shearing comprise: sorting out an undersized steel billet from the obtained steel billets; Counting and finishing the remaining steel billets after sorting out the undersized steel billets; Bundling and weighing of the finished steel billets, and storing by lifting and conveying. A temperature control section is preferably arranged between the respective rolling mills, while no return section is required.

In particular, in the embodiment of the present invention, the chemical composition control is adopted in the manufacturing process of steel bars of the 600 MPa class; The mechanisms of fine-grain reinforcement of the micro-alloys, crystallization rolls, non-recrystallization rolls and deformation-induced ferrite conversion are used in accordance with different rolling speeds and degrees of pressing of the roughing, intermediate and finishing mills, and the temperature control is distributed in each stage, through the continuous temperature control and the deformation rolling process, the refinement and homogenization are used the steel microstructures realized. In terms of process layout, the shortcomings of traditional processes are overcome. A temperature control section is provided between the respective systems and no return section is required. In this manner, various control mechanisms can be extensively used to meet the controlled rolling requirements for various specifications and compositions. After rolling, process measures such as controlled cooling are taken to cool the refined billets, thereby achieving control of the growth of grains and homogenization of microstructures. The present invention ensures the high strength of steel bar products, effectively saves at least 30% of steel consumption, greatly improves the grade structure of current products for buildings, and greatly improves the economic benefit. Preferably the V / N ratio in the raw material for making steel is 3.49-3.83.

Preferably, the main component of the nitrogen booster in the raw material for making steel is ferrosilicon nitride. Preferably, the main component of the nitrogen booster in the raw material for producing steel is silicon manganese nitride. Is preferred

The main component of the nitrogen enhancer in the raw material used to manufacture steel is ferromanganese nitride. Preferably, the percentage of Nb in the raw material for making steel is 0.015-0.025%.

In particular, at present, the method of adding alloying elements is mainly used in China to improve the mechanical properties of steel rods, and the solid solution reinforcing mechanism, the precipitation reinforcing mechanism and the fine grain reinforcing mechanism of alloying elements are used to increase the strength level of the steel rods.

In the manufacture and melting of 600 MPa steel bars, it is a recognized economical and effective method to add a vanadium-nitrogen alloy for microalloying with vanadium and nitrogen, but in actual production the nitrogen content in the steel is relatively low when the vanadium content is used Exceeds 0.10%, the V / N ratio is usually greater than 5, which is much higher than an ideal 3.64 ratio. In this case, the strengthening effect of vanadium cannot be fully exerted, because of this, more vanadium should be added to ensure the strength of the steel rod, resulting in increased production costs and waste of alloy resources. The method of the embodiment of the present invention effectively controls the V / N ratio so that it is in the range of 3.49 to 3, by adding a nitrogen booster with ferrosilicon nitride or silicon manganese nitride or ferromanganese nitride as the main component to stably supplement the required nitrogen in the steel rod. 83 lies in order to fully exert the potentiating effects of vanadium; and by adding a small amount of niobium (0.015-0.025%), the flow ratio and the ultimate strength of the steel rod are increased by the niobium-vanadium composite reinforcement mechanism. This reduces the amount of vanadium required, saving valuable metal resources and lowering production costs. This technology adapts the chemical components and rolling process based on the ordinary steel rods to improve the overall performance of steel rods, and meet the requirements for various indicators of the high-performance steel rods from class 600MPa after quenching and tempering.

Embodiment 2 An embodiment of the present invention provides a 600MPa class steel bar for reinforced concrete suitable for the manufacturing method in the first embodiment, the 600MPa class steel bar for reinforced concrete having the following components in the following percentages: C. : 0.21-0.26%; Mn: 1.40-1.80%; Si: 0.65-0.84%; V: 0.08-0.11%; S <0.020%; P <0.025%; N: 0.023-0.029%; Nb: 0.015-0.025%; the balance being Fe and inevitable impurities.

Preferably, the grains in the steel bar of the 600MPa class for reinforced concrete are no larger than 4 µm.

Preferably the strength of the steel bar is of the 600MPa class for reinforced concrete 600 MPa.

Specifically, the strength of the steel bar of the 600MPa class for reinforced concrete in the embodiment of the present invention is 600 MPa, thereby meeting the requirements of the high-strength steel bar, and the steel bar has the following chemical components in the following percentages: C: 0.21 -0.26%; Mn: 1.40-1.80%; Si: 0.65-0.84%; V: 0.08-0.11%: S <0.020%; P <0.025%; N: 0.023-0.029%; Nb: 0.015-0.025%; the balance being Fe and inevitable impurities.

C is one of the most economical reinforcement elements in steel.

Controlling the C content ensures the strength of the material, and solubilizing reinforcement improves the yield strength.

Si is a deoxidizing element and its solid solution reinforcement in steel ensures the strength of steel.

Mn is a solid solution reinforcing element that improves the yield strength and ensures the toughness.

P is an impurity element in steel; too high a P content reduces the weldability and formability of steel.

S is an impurity element in steel that affects the low temperature toughness of steel.

The solidly dissolved N can increase strength, and too high an N content seriously deteriorates the plasticity and toughness of the material, especially in the case of heat-treated high-strength steel.

Nb is a second phase formation element which exerts a precipitation enhancing effect and has a function of inhibiting the recovery of austenite and grain growth after recrystallization during the hot rolling process to bring the ferrite phase to a desired grain size.

The particles of the second phase are hard and can improve the wear resistance of the matrix.

V is a second phase formation element that has a precipitation enhancing effect.

A certain amount of V improves the strength of the incomplete recrystallization zone of the weld.

In the existing HRB400 and HRB500 products, the content of common alloying elements such as C, Si, Mn etc. is already close to the upper limits specified in the Chinese industrial standard GB 1499 2.

There is not much room for increasing the C, Si and Mn content during the development of HRB600. A good

Weldability is a basic requirement for the universal use of the products.

To ensure processing and welding performance, China's national standards also set clear requirements for microstructure and carbon equivalent.

On the basis of this, the route of the micro-alloying should be selected, and the fine-grain reinforcement used is based on the special process of controlled post-rolling cooling to refine the grains.

However, the actual situation is often much more complicated, making it quite difficult to rely on a single production process for the grains to reach 4 µm or less; in addition, the cost of the V alloy is relatively high and a high alloy content is likely to lead to abnormal microstructures.

To the above

To avoid factors, the embodiment of the present invention uses the alloy process to produce high-strength steel bars of the 600 MPa class by the same production process as the current low and medium strength steel bars, on the one hand, the modification of the production line and the resulting modification of a series of equipment and cost increases can be avoided; on the other hand, it is conducive to the rapid production and distribution of new products on a large scale.

In combination with the control of the chemical composition and correspondingly different rolling speeds and degrees of pressing of the roughing, intermediate and finishing mills, the mechanisms of fine-grain reinforcement of the micro-alloys, crystallization rolls, non-recrystallization rolls and deformation-induced ferrite transformation are used, and the temperature control is distributed in each stage, through the continuous Temperature control and the deformation rolling process, the refinement and homogenization of the steel microstructures are implemented.

In terms of process layout, the shortcomings of traditional processes are overcome.

A temperature control section is provided between the respective systems, and it is not one

Return section required.

In this manner, various control mechanisms can be extensively used to meet the controlled rolling requirements for various specifications and compositions.

An Nb and V composite component system is achieved which has been specially developed to meet the requirements for steel rods of 600 MPa in terms of fine grain, high strength and anti-seismicity.

By modifying the process and adjusting the composition, the rolled steel bar can meet the usage requirement for a high strength of 600 MPa, and at least 30% of the steel consumption is saved, thereby greatly improving the grade structure of the current building products and the economy.

This solves the problem in the prior art that the micro-alloy route is selected so that it is difficult to meet the strength requirement based on a single production process, resulting in high cost.

Preferably, the V / N ratio in the percentage of the steel rod of the 600MPa class for reinforced concrete is not greater than 5. Preferably, the V / N ratio in the percentage of the steel rod of the 600MPa class for reinforced concrete is 3.49-3 , 83. Preferably, the main component of the nitrogen booster in the steel rod of the 600MPa class for reinforced concrete is ferrosilicon nitride.

Preferably, the main component of the nitrogen booster in the steel rod of the 600MPa class for reinforced concrete is silicon manganese nitride.

Preferably, the main component of the nitrogen booster in the steel rod of the 600MPa class for reinforced concrete is the ferro-manganese nitride.

In particular, at present, the method of adding alloying elements is mainly used in China to improve the mechanical properties of steel rods, and the solid solution reinforcing mechanism, the precipitation reinforcing mechanism, and the fine grain reinforcing mechanism of alloying elements are used to increase the strength level of the steel rods.

In the manufacture and melting of 600 MPa steel bars, it is a recognized economical and effective method to add a vanadium-nitrogen alloy for microalloying with vanadium and nitrogen, but in actual production the nitrogen content in the steel is relatively low when the vanadium content is used Exceeds 0.10%, the V / N ratio is usually greater than 5, which is much higher than an ideal 3.64 ratio.

In this case, the strengthening effect of vanadium cannot be fully exerted, because of this, more vanadium should be added to ensure the strength of the steel rod, resulting in increased production costs and waste of alloy resources.

The method of the embodiment of the present invention effectively controls the V / N ratio so that it is in the range of 3.49 to 3, by adding a nitrogen booster with ferrosilicon nitride or silicon manganese nitride or ferromanganese nitride as the main component to stably supplement the required nitrogen in the steel rod. 83 lies in order to fully exert the potentiating effects of vanadium; and by adding a small amount of niobium (0.015-0.025%), the flow ratio and the ultimate strength of the steel rod are increased by the niobium-vanadium composite reinforcement mechanism. This reduces the amount of vanadium required, saving valuable metal resources and lowering production costs. This technology adapts the chemical components and rolling process based on the ordinary steel rods to improve the overall performance of steel rods, and meet the requirements for various indicators of the high-performance steel rods from class 600MPa after quenching and tempering.

The above one or more technical solutions in the embodiments of the present application have at least one or more of the following technical effects:

1. An embodiment of the present invention provides a method of manufacturing the steel bar of the 600MPa class for reinforced concrete, the method comprising: refining a raw material for making steel by a converter to obtain a coarsely refined molten steel; Refining the coarsely refined molten steel by a refining furnace to obtain a refined molten steel; Rolling the refined molten steel through a continuous caster to obtain a continuously cast steel billet; Transferring the continuously cast steel billets to a heating furnace for heating and then feeding the heated steel billets to a stand roughing mill for roughing to obtain a roughed steel billet; after the pre-rolled steel billets are sheared and broken, they are fed to a stand intermediate rolling mill for intermediate rolling to obtain an intermediate rolled steel billet; Subjecting the intermediate-rolled steel billet to a pre-water cooling section for finish-rolling at a low temperature, followed by shearing and breaking, and feeding the steel billet to a stand finish-rolling mill for finish-rolling to obtain a finish-rolled steel billet; Cooling and shearing of the finished rolled steel billet and then finishing and storage. The adjustment of the chemical components and the rolling process on the basis of the ordinary steel rods is realized, thereby improving the overall performance of steel rods that meet the requirements for various indicators of the high-performance steel rods from class 600 MPa after quenching and tempering, thereby making a steelmaking process. and continuous casting technology for highly microalloyed steel billets to avoid surface defects of cast billets, and the solid solution reinforcement, fine grain reinforcement, precipitation reinforcement of microalloy and the corresponding heating technology, controlled rolling technology / controlled cooling rolling technology are combined to form a stable industrial rolling technology, thereby combining the technical Effects of cost reduction and significant improvement in profitability can be achieved. This solves the problem in the prior art that the micro-alloy route is selected so that it is difficult to meet the strength requirement based on a single production process, resulting in high cost.

2. An embodiment of the present invention provides a steel bar of the class 600MPa for reinforced concrete, the steel bar of the class 600MPa for reinforced concrete having the following components in the following percentages: C :, 21-, 26%; Mn: 1.40-1.80%; Si: 0.65-0.84%; V: 0.08-0.11%; S <0.020%; P <0.025%; N: 0.023-0.029%; Nb: 0.015-0.025%; the balance being Fe and inevitable impurities. An Nb and V composite component system is achieved which is specially developed to meet the requirements for the steel rods of 600 MPa in terms of fine grain, high strength and anti-seismicity. By adjusting the process and composition, the rolled steel bar can meet the use requirement for high strength of 600 MPa, and at least 30% of steel consumption is saved, which greatly improves the grade structure of current building products and economy. This solves the problem in the prior art that the micro-alloy route is selected so that it is difficult to meet the strength requirement based on a single production process, resulting in high cost.

Although the preferred embodiments of the present invention have already been explained in more detail, those skilled in the art can make other modifications and changes to these embodiments once they know the essential creative terms. It is therefore intended that the claims be understood to cover the preferred embodiments and all changes and modifications that come within the scope of the present invention.

Of course, those skilled in the art can make various changes and modifications to the embodiment of the present invention without departing from the spirit and scope of the embodiment of the present invention. If these changes and modifications of the embodiment of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, these changes and modifications should also be considered to be included in the scope of the present invention.

Claims (20)

Claims A method of manufacturing the steel bar of the 600MPa class for reinforced concrete, characterized in that the method comprises: refining a raw material for making steel by a converter to obtain a coarsely refined molten steel; Refining the coarsely refined molten steel by a refining furnace to obtain a refined molten steel; Rolling the refined molten steel through a continuous caster to obtain a continuously cast steel billet; Transferring the continuously cast steel billets to a heating furnace for heating and then feeding the heated steel billets to a stand roughing mill for roughing operation to obtain a roughing steel billet; after shearing and breaking the rough rolled steel billet, they are fed to a stand intermediate rolling mill for intermediate rolling to obtain an intermediate rolled steel billet; Subjecting the intermediate-rolled steel billet to a pre-water cooling section for finish-rolling at a low temperature, followed by shearing and breaking, and feeding the steel billet to a stand finish-rolling mill for finish-rolling to obtain a finish-rolled steel billet; The finish-rolled steel billet is cooled and sheared, followed by finishing and storage. 2. The method according to claim 1, characterized in that the method, prior to conveying the continuously cast steel billet to the heating furnace for heating, comprises: inspecting the continuously cast steel billet; and conveying the continuous cast steel billet which passes the inspection by means of a conveyor roller bed into the heating furnace for heating. 3. The method according to claim 1, characterized in that the shearing and breaking of the pre-rolled steel billet comprise: shearing of a steel billet head and a steel billet tail of the pre-rolled steel billet by crank shear and subsequent breaking. 4. The method according to claim 1, characterized in that subjecting the intermediate-rolled steel billet to a pre-water cooling section for finish rolling at low temperature and then shearing and breaking comprises: shearing a steel billet head and a steel billet tail of the finish-rolled steel billet by rotary shear and then breaking. 5. The method according to claim 1, characterized in that the cooling and shearing of the finish-rolled steel billet and subsequent finishing and storage comprise: subjecting the finish-rolled steel billet to a water cooling section for controlled cooling; Performing segmented shear on the cooled finish rolled steel billet using multiple length shear; After natural cooling in a cooling bed, the sheared, finish-rolled steel billet is sheared to a fixed length with cold shears; and finishing and storing the steel billet obtained after shearing. 6. The method according to claim 5, characterized in that the finishing and storing of the steel billet obtained after shearing comprise: sorting out an undersized steel billet from the obtained steel billets; Counting and finishing the remaining steel billets after sorting out the undersized steel billets; Bundling and weighing of the finished steel billets, and storing by lifting and conveying. 7. The method according to claim 1, characterized in that a temperature control section is arranged between the respective rolling mills, while no return section is required. 8. The method according to claim 1, characterized in that the V / N ratio in the raw material for making steel is 3.49-3.83. 9. The method according to claim 8, characterized in that the main component of the nitrogen booster in the raw material for making steel is ferrosilicon nitride. 10. The method according to claim 8, characterized in that the main component of the nitrogen booster in the raw material for producing steel is the silicon manganese nitride. 11. The method according to claim 8, characterized in that the main component of the nitrogen booster in the raw material for producing steel is the ferromanganese nitride. 12. The method according to claim 1, characterized in that the percentage of Nb in the raw material for making steel is 0.015-0.025%. A steel rod of the class 600MPa for reinforced concrete, which is suitable for the manufacturing method according to any one of claims 1 to 12, wherein the steel rod of the class 600MPa for reinforced concrete has the following components in the following percentage contents: C: 0.21-0 , 26%; Mn: 1.40-1.80%; Si: 0.65-0.84%; V: 0.08-0.11%; S <0.020%: P <0.025%; N: 0.023-0.029%; Nb: 0.015-0.025%; the balance being Fe and inevitable impurities. 14. Steel bar of the class 600MPa for reinforced concrete according to claim 13, characterized in that the V / N ratio in the percentage content of the steel bar of the class 600MPa for reinforced concrete is not greater than 5. A steel bar of the class 600MPa for reinforced concrete according to claim 14, characterized in that the V / N ratio in the percentage of the steel bar of the class 600MPa for reinforced concrete is 3.49-3.83. 16. A steel rod of the 600MPa class for reinforced concrete according to claim 13, characterized in that the grains in the steel rod of the 600MPa class for reinforced concrete are not larger than 4 µm. 17. Steel bar of the class 600MPa for reinforced concrete according to claim 13, characterized in that the strength of the steel bar of the class 600MPa for reinforced concrete is 600MPa. 18. A steel rod of the class 600MPa for reinforced concrete according to claim 13, characterized in that the main component of the nitrogen booster in the steel rod of the class 600MPa for reinforced concrete is ferrosilicon nitride. 19. A steel rod of the class 600MPa for reinforced concrete according to claim 13, characterized in that the main component of the nitrogen booster in the steel rod of the class 600MPa for reinforced concrete is the silicon manganese nitride. 20. A steel rod of the class 600MPa for reinforced concrete according to claim 13, characterized in that the main component of the nitrogen booster in the steel rod of the class 600MPa for reinforced concrete is the ferro-manganese nitride.