CN114657460A

CN114657460A - HRB400E spiral reinforcement steel wire rod processed by microalloying rare earth and nitrogen and production method thereof

Info

Publication number: CN114657460A
Application number: CN202210155501.1A
Authority: CN
Inventors: 吴光亮; 吴昊天; 肖业明
Original assignee: CHANGSHA DONGXIN ENVIRONMENTAL PROTECTION MATERIAL CO LTD; Central South University
Current assignee: CHANGSHA DONGXIN ENVIRONMENTAL PROTECTION MATERIAL CO LTD; Central South University
Priority date: 2022-02-21
Filing date: 2022-02-21
Publication date: 2022-06-24

Abstract

The invention discloses a rare earth and nitrogen microalloyed HRB400E spiral steel bar and a production method thereof, which utilize the precipitation strengthening function of trace rare earth and nitrogen in the steel bar to partially replace solid solution strengthening elements manganese and silicon and partially or completely replace vanadium or niobium, adopt controlled rolling and controlled cooling process, and solve the technical problems of large performance difference (generally 30-50MPa) of the same coil of the spiral and unobvious tensile yield platform by controlling phase change and two-phase particle precipitation in the rolling and cooling processes, wherein the performance difference of the same coil of the spiral is less than 10MPa, and the steel bar structure is ferrite plus pearlite. The invention utilizes the existing smelting and rolling equipment to produce HRB400E spiral reinforcing steel bars meeting the GB/T1499.2-2018 standard on the premise of not increasing any investment, the comprehensive cost is reduced by 15-50 yuan/ton compared with the traditional method, the natural aging is carried out for three months, the fluctuation values of Rel and Rm values are less than 10MPa, the welding performance is good, and the reinforcing steel bars have obvious yield platforms when being subjected to tensile test, but not only yield points.

Description

HRB400E spiral reinforcement steel wire rod processed by microalloying rare earth and nitrogen and production method thereof

Technical Field

The invention belongs to the technical field of preparation of spiral steel bars, and particularly relates to a rare earth and nitrogen microalloyed HRB400E spiral steel bar and a production method thereof.

Background

The hot rolled ribbed steel bar for reinforced concrete is delivered from hot rolling in shapes of straight deformed steel bar and wire rod deformed steel bar, wherein the diameter of the wire rod deformed steel bar is mainly 6-12 mm. The main rolling process comprises the following steps: heating a steel billet, rolling by a rough rolling unit, rolling by a medium rolling unit, cooling by a cooling water tank in a group A, rolling by a pre-finishing rolling unit, cooling by a cooling water tank in a group B, rolling by a finishing rolling unit, cooling by a cooling water tank in a group C, reducing the diameter of a unit, spinning a wire, cooling by a Stelter loose coil and collecting the coil. With the implementation of the new national standard GB/T1499.2-2018, the microstructure of the deformed steel bar is clearly regulated and limited, the forced water-penetrating process of the deformed steel bar by utilizing the waste heat after rolling for online heat treatment is limited, and the finished steel bar in a hot rolling state is not allowed to have a tempered martensite structure. If steel bar production enterprises do not carry out micro-alloying and controlled rolling and controlled cooling process technical innovation, the requirements of new standards on organization and performance can only be met by greatly improving the contents of elements such as silicon, manganese, vanadium, niobium and the like in steel. However, on one hand, the dosage of the alloy such as silicon, manganese alloy, vanadium, niobium and the like is increased, so that the quantitative production is increased, and the resource and environmental load is increased, which is contrary to the current 'carbon peak, carbon neutralization'; on the other hand, the production cost of the spiral steel bar is greatly increased, and huge cost pressure is brought to steel bar production enterprises.

In addition, according to the characteristics of the existing equipment and process for manufacturing the wire rod deformed steel bar, the wire rod deformed steel bar has the following technical problems: the lap joint point has low cooling rate and uneven cooling, so that the performance difference of the same ring is large; when the arc-shaped steel bar is made into a straight strip-shaped tensile sample, deformation stress exists, and the tensile property data of the steel bar is different from the actual performance value of the spiral shell; due to the existing component control and rolling and cooling process characteristics of the spiral shell, no obvious yield point or platform exists in the tensile test.

After the new standard is implemented, the low-component or ultra-low-component design is adopted, only carbon, silicon and manganese alloying is adopted, and the process of quenching by using the waste heat after the rolling of the steel bars, namely the process of forced water penetration, is eliminated.

At present, three major types of HRB400EMPa disc spiral steel bars meeting the new national standard requirements of GB/T1499.2-2018 are produced in the prior art. One is a high-temperature rolling process route adopting high-component design and uncontrolled rolling and cooling. The steel is mainly designed by taking a carbon-manganese steel component system based on 20MnSi components and vanadium or niobium or titanium as microalloying elements, manganese and silicon are alloyed by manganese-based and silicon-based ferroalloys, vanadium microalloying is carried out by vanadium iron or vanadium-nitrogen alloys, niobium microalloying is carried out by utilizing the niobium-iron alloys, titanium or boron microalloying is carried out by utilizing the ferrotitanium or boron ferroalloys, the main components are controlled to [ Mn ] between 1.2 and 1.6 percent, [ Si ] between 0.40 and 0.80 percent, [ C ] between 0.17 and 0.25 percent and [ V ] between 0.02 and 0.05 percent or [ Nb ] between 0.020 and 0.05 percent or [ Ti ] between 0.015 and 0.025 percent, or niobium-vanadium-titanium composite microalloying or vanadium-titanium composite microalloying is adopted, the high temperature of wire laying is generally above 880 ℃, the produced coil screw strength (Rel) is not less than 400MPa, the tensile strength is more than or equal to 550MPa, and the reduction of area (A) is more than or equal to 17 percent. The method is the most traditional and mature method for producing the steel bar, and has stable product quality, good service performance and good shock resistance. However, this method has the following problems: the contents of silicon, manganese and carbon are high, high vanadium, niobium or titanium needs to be added, the unit consumption of the alloy is high, and the cost is high; secondly, element segregation is easy to generate in the solidification and cooling processes; high carbon equivalent and poor welding performance; fourthly, the phenomena of unobvious yield and mixed crystals are easy to occur; when the niobium microalloying is used, the high-temperature plasticity of the steel is poor, and when the continuous casting drawing speed exceeds 3 m/min, quality defects such as casting blank cracks, stripping and the like and even steel leakage accidents occur easily; niobium is used as a microalloying element, and the heating temperature of a billet needs to be increased to ensure that niobium carbonitride is redissolved in austenite, so that adverse effects such as increase of billet burning loss, increase of energy consumption, reduction of the service life of a heating furnace and the like can be caused; when titanium or boron is used as a microalloying element, the titanium and boron elements are very easily combined with oxygen, sulfur and nitrogen in steel, and unless the elements in the steel are controlled to be low, the yield of the titanium or boron elements is unstable, the performance fluctuation of steel bars is large, the defect rate of the surface quality of casting blanks is high, and the requirements of industrial scale production are difficult to meet. And the advantages and characteristics of the process equipment for controlling rolling and cooling of the rolling line are not fully exerted. And the proportion of no obvious yield platform exceeds 98 percent in a tensile test under the steel bar.

The second HRB400EMPa spiral steel bar adopts a low-component design, for example, silicon and manganese are controlled according to the lower limit component of 20MnSi, little or no microalloying elements such as vanadium, niobium, titanium, boron or the combination of the vanadium, the niobium, the titanium and the boron are added, a low-temperature or ultralow-temperature rolling process is adopted, for example, the initial rolling temperature is below 950 ℃ or even about 800 ℃, the rolling is carried out at a low temperature and a large deformation amount, the ultrafine crystal steel is produced, and the grain refinement and the dislocation density improvement are taken as main means for improving the strength of the steel bar. The method is still in the industrial test popularization stage at present, and simultaneously has the following defects: the load capacity of the rolling mill needs to be greatly increased, the equipment investment is greatly increased, and the fixed asset investment caused by the reconstruction of an old rolling mill is greatly increased; the produced steel bar can not be welded conventionally, otherwise, the strength of the steel bar is greatly reduced due to the growth of crystal grains in a welding area; the strength-to-yield ratio of the steel bar is reduced, and the shock resistance is reduced; if the rolling temperature is too low, the steel bar is rolled in a two-phase region, and the steel bar is easy to have mixed crystal tissues, so that the performance fluctuation of the steel bar is large. The low-temperature rolling brings the power consumption rise in the rolling process, the consumption of guide and guard and rollers rises, and the frequency of roller replacement and groove replacement is increased; the steel bar stacking accident can be caused by the excessively low temperature of the steel bars, and the production efficiency is not improved. Sixthly, more than 95 percent of HRB400EMPa disc spiral steel bars produced by the method have no obvious yield platform in the tensile test.

And the third type is based on 20MnSi component, solid solution strengthening elements such as silicon, manganese and the like are controlled according to middle and lower limits, microalloying elements such as vanadium, niobium, titanium, boron and the like are added to be rarely used, a proper heating system, a proper deformation system and a cooling system after rolling are selected, a controlled rolling and controlled cooling process is carried out, namely a weak water penetration process or a sectional cooling recovery process is adopted, and the HRB400EMPa spiral reinforcing steel bar meeting the new national standard requirements of GB/T1499.2-2018 can be produced on the premise of reducing the alloy components. The following disadvantages exist: firstly, water passing equipment is required to be added, and investment is increased; secondly, the performance fluctuation of the steel bar is large, and the aging phenomenon is serious; the welding performance is poor; fourthly, the steel bars are easy to rust and have poor shock resistance; fifthly, the surface of the steel bar is inconsistent with the structure of the core part, tempered martensite is easily generated on the surface, and the requirement is higher than the basic requirement that the steel bar structure is ferrite and pearlite in the national standard.

Disclosure of Invention

Aiming at various technical problems existing in the existing production of HRB400EMPa spiral steel bars, in particular to the defects that the production cost of the steel bars is high, no obvious yield platform or even no obvious yield point exists during tensile test, the steel bars are rusted and tempered martensite structures appear after the spinning temperature is too low, and the like, the invention aims to provide the HRB400E spiral steel bars subjected to rare earth and nitrogen microalloying treatment.

The second purpose of the invention is to provide a production method of HRB400E spiral steel bar treated by rare earth and nitrogen microalloying. According to the production method, the HRB400EMPa spiral steel bar which completely meets the new national standard requirement of GB/T1499.2-2018 is produced by taking carbon, silicon and manganese as main alloys, adding trace rare earth and nitrogen as microalloying elements and combining a controlled rolling and controlled cooling process, and the steel bar has an obvious yield platform in a tensile test instead of only an obvious yield point.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention relates to a rare earth and nitrogen microalloying treated HRB400E spiral steel bar, wherein the HRB400E spiral steel bar comprises the following chemical components in percentage by weight: 0.18-0.25 wt% of C, 0.20-0.60 wt% of Si, 0.8-1.25 wt% of Mn, 0.006-0.0120 wt% of N, 0.0015-0.0045 wt% of Sigma Re, and 0.005-0.025 wt% of X, wherein the X is selected from V and/or Nb, and the balance of iron and inevitable impurity elements.

The HRB400E spiral reinforcement provided by the invention fully utilizes precipitation strengthening and phase change strengthening effects of rare earth and nitrogen on the reinforcement, partially replaces solid solution strengthening elements of manganese and silicon, simultaneously utilizes cheap nitrogen elements and a plurality of trace rare earth to carry out micro alloying treatment on the reinforcement, exerts the function of forming carbonitride with trace rare earth and carbon nitride, strengthens the precipitation strengthening effect, simultaneously utilizes the function of nitrogen expanding an austenite region, reduces the lower limit temperature of pearlite transformation, improves the proportion of pearlite and refines the size of pearlite, thereby greatly reducing the dosage of strategic precious metal elements such as vanadium, niobium and the like, realizing low-cost production of HRB400E spiral reinforcement with high strength grade and stable quality and popular in the market.

Preferably, the Σ Re is selected from at least one or a combination of several of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), dysprosium (Dy), ytterbium (Yb), yttrium (Y), and scandium (Sc).

Preferably, when X is selected from V, the weight percentage of X in the HRB400E spiral steel plate is as follows: 0.005 wt% -0.020 wt%, when X is Nb, the weight percentage of X in HRB400E spiral steel bar is 0.005 wt% -0.020 wt%; when X is selected from V and Nb, the weight percentage of X in HRB400E disc spiral steel bar is 0.005 wt% -0.025 wt%.

In the preferable scheme, Rel of the HRB400E spiral steel rod is between 435-495MPa, Rm is between 595-645MPa, A is between 25-35%, Rm/Rel is between 1.31-1.41, and the cold bending qualification rate is 100%; the welding carbon equivalent is less than or equal to 0.45, the aging is carried out for three months, the fluctuation values of Rel and Rm values are less than 10MPa, and the structure of the disc spiral steel bar is as follows: the ferrite and pearlite are 100%, the performance difference of the same-circle spiral steel bar is less than 10MPa, and the tensile curve has an obvious yield platform.

The invention relates to a production method of HRB400E spiral steel bar processed by rare earth and nitrogen microalloying, which comprises the following steps:

step one, smelting molten steel

Firstly, at least one of blast furnace molten iron, scrap steel, pig iron and reduced iron is taken as an iron-containing raw material, smelting is carried out, a slagging agent is added, and a silicon-manganese alloy or a ferromanganese alloy, a ferrosilicon alloy, a rare earth-nitrogen alloy, a rare earth alloy, a vanadium-nitrogen alloy or a ferrocolumbium alloy and a carburant are added in the process of tapping to obtain molten steel which meets the content of designed components,

step two casting

Continuously casting the molten steel in a continuous casting process to obtain a continuous casting billet;

rolling in step three

Conveying the continuous casting billet obtained in the step two to a heating furnace for heating, and then rolling the heated continuous casting billet to obtain the disc spiral steel bar, wherein in the rolling process: the initial rolling temperature is controlled to be 950-: 80-130m/s, and the spinning temperature is 700-900 ℃;

step four

And (3) rolling the spiral steel bar obtained in the step three, then controlling cooling, firstly cooling to 560-.

According to the invention, the cooling fan is used for adjusting the cooling strength during the steel bar cooling, three sections of different cooling rates are adopted to ensure that the obtained structure is ferrite (F) + pearlite (P), and the obtained microstructure is finer and the grain size level is higher. The high-temperature section adopts higher cooling strength, rapidly cools, promotes the formation of pearlite and ferrite, particularly pearlite and pro-eutectoid ferrite, controls the growth of the pearlite and the pro-eutectoid ferrite, but the cooling rate is not too high, the martensite or bainite can be formed when the cooling rate is too high, and simultaneously promotes the precipitation of rare earth carbonitride, ensures that the rare earth carbonitride precipitate is uniformly distributed along the whole cross section of the steel bar so as to block dislocation movement and increase the strength; reducing the cooling rate to below 560 ℃ to promote the tissue and uniform precipitation without growing; and finally, cooling at a low cooling rate, wherein the cooling is carried out under a similar air cooling condition, so that the thermal stress is reduced, and the performance uniformity is ensured.

Preferably, in the first step, blast furnace molten iron, or one or two of the blast furnace molten iron and scrap steel or pig iron blocks are added into a converter for oxygen blowing smelting, and a slag former is added, so that the loading of the converter scrap steel is controlled to be 15-30% of the total loading; the end point adopts a high-carbon-drawing-steel pouring process; controlling the end point C of the converter to be 0.06-0.20%; the tapping temperature is 1580 and 1650 ℃; slag stopping and tapping, wherein the thickness of a ladle slag layer is less than or equal to 100 mm; according to the requirements of the terminal components of the converter and the components of HRB400E spiral steel bars, silicon-manganese alloy or ferromanganese alloy, silicon-iron alloy, rare earth nitrogen alloy, rare earth alloy, vanadium-nitrogen alloy and carburant are added before molten steel is discharged to 2/3, the ladle is blown at the bottom in the whole tapping process and stirred, argon or nitrogen is blown in an argon station after steel is discharged and stirred for 4-12min, then temperature measurement and sampling are carried out, the components of the HRB400E spiral steel bars are adjusted to target values, and the temperature of the argon station is controlled to be between 1555 ℃ and 1610 ℃.

Preferably, in the first step, scrap steel and pig iron blocks or reduced iron are used as iron-containing raw materials, oxygen blowing and power transmission smelting are carried out in an electric furnace, a slag former is added, molten steel C at the end point of the electric furnace is controlled to be 0.10-0.20%, steel is retained, the steel retaining amount is 1/3 (for example, about 30 tons of steel retaining amount of 100 tons of electric furnace) of the total molten steel amount, and eccentric bottom tapping is carried out; the tapping temperature is 1570-; transferring the molten steel to an LF furnace for sampling, adding a slag making material, properly increasing the amount of bottom-blown argon, blowing off top slag on the surface of the molten steel, then adding a nitriding alloy (such as a micro-nitrogen alloy, a rare earth nitrogen alloy and the like) according to the outbound components and target components of the electric furnace, then transmitting power for 3-7 minutes for the first time, and simultaneously starting ladle bottom-blown argon stirring to ensure that the top slag of the ladle covers the liquid level of the molten steel and the molten steel is not exposed; after the first power transmission is finished, adding microalloying element alloy (such as vanadium-containing alloy, niobium-containing alloy, titanium-containing alloy or combination alloy of the vanadium-containing alloy, the niobium-containing alloy and the titanium-containing alloy) according to the components entering the LF station and the target components, then carrying out power transmission for 5-10 minutes for the 2 nd time to generate foamed yellow slag and tapping, so that the components reach the target components of HRB400E disc spiral steel bars, and the leaving temperature is 1550-.

Further preferably, a double-station ultrahigh-power quantum electric furnace is adopted for smelting, scrap steel is preheated by electric furnace smoke and a continuous scrap steel adding process is adopted; the electric furnace adopts at least one of a furnace door carbon-oxygen spray gun and a furnace wall oxygen gun to input chemical heat to the maximum extent.

According to the preferable scheme, a ladle long nozzle and a crystallizer submerged nozzle are adopted for casting protection in the casting process, alkaline casting powder is adopted as the crystallizer casting powder, and the superheat degree of the tundish molten steel in continuous casting is as follows: 15-30 ℃; the section size of the continuous casting billet is 180mm plus 150mm plus; the continuous casting speed is controlled at 2.5-4.5 m/min.

According to the preferable scheme, when the continuous casting billet is heated, the temperature of a hot soaking section is 1000-1160 ℃, and the temperature difference of the section of the continuous casting billet is less than 40 ℃. In the actual operation process, overheating and overburning are avoided, and the temperature of the surface and the core of the steel billet is ensured to be uniform.

In the actual operation process, in the rolling process, water cooling is adopted between the racks, a water cooling tank is arranged in front of the pre-finishing mill set, the water cooling tank is arranged between the pre-finishing mill and the finishing mill, and the water cooling tank is arranged after the finishing mill to ensure the temperature control of a rolled piece in the rolling process.

In the cooling process after the steel bar is rolled, the steel bar is rapidly cooled to 560 ℃ and 630 ℃ at the speed of 2-6 ℃/s in the front half section of the stelmor air-cooled roller way; then cooling to 400-550 ℃ at the speed of 1.5-2.2 ℃/s, and finally cooling to below 400 ℃ at the speed of 0.2-0.8 ℃/s for coiling.

Advantageous effects

The invention provides a rare earth and nitrogen microalloyed HRB400E spiral shell reinforcing steel bar, which fully utilizes the precipitation strengthening and phase transformation effects of rare earth and nitrogen on the reinforcing steel bar to partially replace solid solution strengthening elements of manganese and silicon, simultaneously utilizes cheap nitrogen elements and a plurality of trace rare earth to carry out microalloyed treatment on the reinforcing steel bar, exerts the function of forming carbonitride by trace rare earth and carbon nitride, strengthens the precipitation strengthening effect, simultaneously utilizes the function of nitrogen for expanding an austenite region, reduces the pearlite transformation lower limit temperature, improves the pearlite proportion, refines the size of pearlite, greatly reduces the dosage of noble metal elements such as vanadium, niobium and the like, and realizes the low-cost and quantitative production of the HRB400E spiral shell reinforcing steel bar with high strength level, stable quality and popular market.

The production process of the invention fully utilizes different trace rare earth and microalloying elements such as nitrogen, vanadium or niobium and the like to form different types of carbonitride precipitates, adopts a rolling and cooling control process to control phase change and structure change in the rolling and cooling processes, solves the technical problem that the performance difference of the same ring of the disc spiral is large (generally between 30 and 50MPa), the performance difference of the same ring of the disc spiral is less than 10MPa, and the steel bar structure is ferrite plus pearlite.

The spiral reinforcing steel bar produced by the invention comprises the following components: c is more than or equal to 0.18 weight percent and less than or equal to 0.25 weight percent, Si is more than or equal to 0.20 weight percent and less than or equal to 0.60 weight percent, Mn is more than or equal to 0.80 weight percent and less than or equal to 1.25 weight percent, N is more than or equal to 0.006 weight percent and less than or equal to 0.0120 weight percent, Sigma Re is more than or equal to 0.0015 weight percent and less than or equal to 0.0045 weight percent, and V is more than or equal to 0.005 weight percent and less than or equal to 0.020 weight percent when V does not contain Nb in molten steel; when the Nb in the molten steel does not contain V, the Nb content is more than or equal to 0.005 wt% and less than or equal to 0.020 wt%; and when the alloy contains V and Nb, the sum of V and Nb is more than or equal to 0.005 wt% and less than or equal to 0.025 wt%, and the balance of iron and inevitable impurity elements.

The HRB400E spiral steel bar with the diameter of 6mm-12mm produced by the invention has Rel between 435-495MPa, Rm between 595-645MPa, A between 25-35 percent, Rm/Rel between 1.31-1.41 and the cold bending qualification rate of 100 percent; the welding carbon equivalent is less than or equal to 0.45, and the welding performance is good; aging for three months, wherein the fluctuation values of Rel and Rm values are less than 10MPa, and the structure of the steel bar of the spiral is as follows: ferrite + pearlite is 100%, and the steel bar has a remarkable yield platform when being subjected to a tensile test, and not only a remarkable yield point. The performance difference of the same-circle spiral steel bar is less than 10 MPa.

The invention utilizes the existing smelting and rolling equipment to produce HRB400E spiral steel bars meeting the GB/T1499.2-2018 standard requirements on the premise of not increasing any investment, and the comprehensive cost is reduced by 15-50 yuan/ton compared with the traditional method;

Detailed Description

The present invention will be described in further detail with reference to examples, but the present invention is not limited thereto.

The invention can adopt the process of oxygen converter smelting-continuous casting-rolling, and also can adopt the process of electric furnace smelting-continuous casting-rolling. The specific embodiment of the invention is implemented by adopting an oxygen converter smelting or electric furnace smelting-continuous casting-rolling process.

Example 1

100 tons of blast furnace molten iron and 22 tons of scrap steel are respectively added into a 120-ton converter, oxygen blowing smelting is carried out, slagging materials such as lime, sintered ore or ore, fluorite, dolomite and the like are added, when the oxygen blowing smelting of the converter is carried out for 18min, the converter is turned down, sampling and temperature measuring tapping are carried out, the [ C ] in the molten steel at the end point of the converter is 0.11 percent, the [ Mn ] is between 0.16 percent, the [ O ] is 567PPm, and the tapping temperature is 1637 ℃; slag stopping and tapping, wherein the thickness of a ladle slag layer is 58 mm; when the converter molten steel is discharged to 2/3, all the silicon-manganese alloy, the silicon-iron alloy, the rare earth nitrogen alloy, the rare earth alloy, the vanadium-nitrogen alloy and the recarburizer are added, the whole bottom blowing stirring of a steel ladle in the tapping process is completed, the nitrogen blowing atmosphere stirring is carried out for 4min in an argon station after the steel is discharged, the soft blowing stirring is carried out for 6min, the temperature measurement and the sampling are carried out, and the components of the HRB400E spiral steel bar: 0.21 wt% of C, 0.25 wt% of Si, 1.05 wt% of Mn, 0.0102 wt% of N and 0.0015 wt% of Sigma Re, wherein the Sigma Re is the sum of the contents of La, Eu and Gd in the molten steel, and 0.011 wt% of V in the molten steel; the temperature of the argon station is 1605 ℃, and the furnace 1 is poured into the tundish.

And the ladle long nozzle and the crystallizer submerged nozzle are used for casting protection, and the crystallizer casting powder is alkaline casting powder. Superheat degree of molten steel in continuous casting tundish: 29 ℃; the section size of the continuous casting billet is 180mm multiplied by 180 mm; the continuous casting speed is controlled to be 2.58 m/min;

and (3) heating the casting blank, wherein the temperature of a hot soaking section is 1156 ℃, the surface temperature and the core temperature of the steel blank are uniform, and the temperature difference of the section of the same blank is less than 20 ℃. The initial rolling temperature: 958 deg.C. The water cooling is adopted between the racks, a water cooling box is arranged in front of the pre-finishing mill group, the temperature of a rolled piece entering the pre-finishing mill group is 928 ℃, the water cooling box is arranged between the pre-finishing rolling and the finish rolling, the temperature of the rolled piece entering the finishing mill group is 887 ℃, the water cooling box is arranged after the finish rolling, the temperature of the rolled piece entering the reducing mill group is 805 ℃, and the wire laying temperature of the coiled steel bar: 708 ℃. Final gantry speed: 86 m/s.

Rapidly cooling to 569 deg.C at 2.6 deg.C/s in the first half of stelmor air-cooled roller bed; then cooling to 412 ℃ at the speed of 1.52 ℃/s, and finally cooling to below 391 ℃ at the speed of 0.28 ℃/s for coiling.

Taking 4 groups of mechanical property samples from each rolling batch for tensile test, wherein the mechanical properties are as follows: rel is between 443 and 468MPa, the mean value is 457.8MPa, Rm is between 602 and 616MPa, the mean value is 609.2MPa, A is between 25 and 28 percent, the mean value is 26.6 percent Rm/Rel is between 1.32 and 1.33, the mean value is 1.324, and the cold bending percent of pass is 100 percent; aging for three months, wherein the Rel value fluctuation value is 5.7MPa, the Rm value fluctuation value is 2.1MPa, and the welding performance is good; the spiral steel bar structure is as follows: the ferrite and the pearlite account for 100 percent, and the steel bar has an obvious yield platform when being subjected to a tensile test; the maximum value of the performance difference of the same coil spiral steel bar is 8.6 MPa. The comprehensive cost is reduced by 22.7 yuan/ton compared with the conventional HRB400E spiral shell.

Comparative example 1 example of rare earth free HRB400E coiled steel bar.

The other conditions are the same as those of the example 1, only the components do not contain rare earth, and the mechanical property detection result is as follows: rel is between 398 and 421MPa, the average value is 407.4MPa, Rm is between 535 and 567MPa, the average value is 548.2MPa, A is between 24 and 30 percent, the average value is 27.6 percent Rm/Rel is between 1.31 and 1.35, the average value is 1.354, and the cold bending percent of pass is 100 percent; aging for three months, the fluctuation value of Rel value is 7.2MPa, the fluctuation value of Rm value is 3.1MPa, and the welding performance is good. The maximum value of the performance difference of the same coil spiral steel bar is 25.2 MPa.

Example 2

90 tons of blast furnace molten iron and 32 tons of scrap steel are respectively added into a 120-ton converter, oxygen blowing smelting is carried out, slagging materials such as lime, sintered ore or ore, fluorite, dolomite and the like are added, when oxygen blowing smelting is carried out in the converter for 16min, the converter is turned over, sampled and temperature measured to carry out tapping, wherein [ C ] is 0.08 percent, [ Mn ] is between 0.13 percent, [ O ] is 721PPm, and the tapping temperature is 1589 ℃; slag stopping and tapping, wherein the thickness of a ladle slag layer is 62 mm; when the converter molten steel is discharged to 2/3, manganese-iron alloy, silicon-iron alloy, rare earth-nitrogen alloy, rare earth alloy, ferroniobium alloy and carburant are completely added, the whole bottom blowing stirring of a steel ladle in the tapping process is carried out, after the steel is discharged, nitrogen blowing and atmosphere stirring are carried out for 2.5min in an argon station, the soft blowing stirring is carried out for 4min, the temperature is measured, the sampling is carried out, and the components of HRB400E spiral steel bars are as follows: c is 0.23 wt%, Si is 0.35 wt%, Mn is 0.95 wt%, N is 0.0087 wt%, and Sigma Re is 0.0023 wt%, where Sigma Re is the total content of Pr, Nd, Pm and Sm in molten steel, and Nb is 0.015 wt%; the argon station exit temperature was 1568 ℃.

And the ladle long nozzle and the crystallizer submerged nozzle are used for casting protection, and the crystallizer casting powder is alkaline casting powder. Superheat degree of molten steel in continuous casting tundish: 29 ℃; the section size of the continuous casting billet is 170mm multiplied by 170 mm; the continuous casting speed is controlled to be 3.42 m/min;

and (3) heating the casting blank, wherein the temperature of a hot soaking section is 1143 ℃, the surface temperature and the core temperature of the steel blank are uniform, and the temperature difference of the same blank section is less than 35 ℃. The initial rolling temperature: 1017 ℃. The water cooling is adopted between the racks, a water cooling box is arranged in front of the pre-finishing mill group, the temperature of a rolled piece entering the pre-finishing mill group is 996 ℃, the water cooling box is arranged between pre-finishing rolling and finishing rolling, the temperature of the rolled piece entering the finishing mill group is 960 ℃, the water cooling box is arranged after finishing rolling, the temperature of the rolled piece entering the reducing mill group is 926 ℃, and the wire laying temperature of the coiled steel bar: 892 deg.C. Final gantry speed: 125 m/s.

Rapidly cooling to 625 deg.C at 5.6 deg.C/s in the front half of stelmor air-cooled roller bed; then cooling to 546 ℃ at the speed of 2.15 ℃/s, and finally cooling to below 388 ℃ at the speed of 0.75 ℃/s for coiling.

Taking 6 groups of mechanical property samples from each rolling batch for tensile test, wherein the mechanical properties are as follows: rel is between 446 and 473MPa, the mean value is 459.1MPa, Rm is between 604 and 618MPa, the mean value is 611.3MPa, A is between 25 and 29 percent, the mean value is 26.1 percent Rm/Rel is between 1.30 and 1.36, the mean value is 1.336, and the cold bending percent of pass is 100 percent; aging for three months, wherein the Rel value fluctuation value is 4.7MPa, the Rm value fluctuation value is 3.1MPa, and the welding performance is good; the spiral steel bar structure is as follows: the ferrite and the pearlite account for 100 percent, and the steel bar has an obvious yield platform when being subjected to a tensile test; the maximum value of the performance difference of the same coil spiral steel bar is 5.6 MPa. The comprehensive cost is reduced by 21.2 yuan/ton compared with the conventional HRB400E spiral shell.

Comparative example 2: the cooling system is beyond the set range.

The other conditions are the same as the example 2, and after the wire is spun by the spiral shell, the wire is rapidly cooled to 625 ℃ at the speed of 1.0 ℃/s in the front half section of a stelmor air-cooled roller way; then cooling to 546 ℃ at the speed of 1.0 ℃/s, and finally cooling to below 388 ℃ at the speed of 0.15 ℃/s for coiling. The measured mechanical properties are as follows: rel is between 396 and 423MPa, the mean value is 409.1MPa, Rm is between 536 and 567MPa, the mean value is 541.3MPa, and the others are all qualified; the spiral steel bar structure is as follows: the ferrite and the pearlite account for 100 percent, and the steel bar has an obvious yield platform when being subjected to a tensile test, and the performance difference of the same ring is 26.2MPa at most; the performance is lower than the national standard requirement.

Example 3

105 tons of blast furnace molten iron and 18 tons of pig iron blocks are respectively added into a 120-ton converter for oxygen blowing smelting, slagging materials such as lime, sinter ore or ore, fluorite, dolomite and the like are added, when the converter oxygen blowing smelting is carried out for 17min, the converter is turned over, sampled and temperature-measured to carry out tapping, the [ C ] in the molten steel at the end point of the converter is 0.018%, the [ Mn ] is between 0.15%, the [ O ] is 517PPm, and the tapping temperature is 1631 ℃; slag stopping and tapping, wherein the thickness of a ladle slag layer is 79 mm; when the converter molten steel is discharged to 2/3, all the addition of silicon-manganese alloy, silicon-iron alloy, rare earth nitrogen alloy, rare earth alloy, vanadium-nitrogen alloy, ferroniobium alloy and carburant is completed, the whole bottom blowing stirring of a steel ladle in the tapping process is completed, after the steel is discharged, the nitrogen-blowing atmospheric stirring is carried out for 2min in an argon station, the soft blowing stirring is carried out for 6min, the temperature is measured, the sampling is carried out, and the components of HRB400E spiral steel bars are as follows: 0.24 wt% of C, 0.55 wt% of Si, 0.81 wt% of Mn, 0.0118 wt% of N and 0.0035 wt% of Sigma Re, wherein the Sigma Re is the sum of the contents of Sm, Eu, Gd and Dy in molten steel, 0.005 wt% of Nb and 0.008 wt% of V in the molten steel; the argon station exit temperature is 1577 ℃.

And the ladle long nozzle and the crystallizer submerged nozzle are used for casting protection, and the crystallizer casting powder is alkaline casting powder. Superheat degree of molten steel in continuous casting tundish: 26 ℃; the section size of the continuous casting billet is 150mm multiplied by 150 mm; the continuous casting speed is controlled at 4.45 m/min;

heating the casting blank, wherein the temperature of a hot soaking section is 1109 ℃, the temperature of the surface and the core of the steel blank is uniform, and the temperature difference of the section of the same blank is less than 24 ℃. The initial rolling temperature: 1047 ℃. Adopt water-cooling between the frame, set up the water cooling tank before the finishing mill group in advance, rolled piece advances finishing mill group temperature 982 in advance, sets up the water cooling tank between finish rolling and the finish rolling in advance, and rolled piece advances finishing mill group temperature 931 ℃, sets up the water cooling tank after the finish rolling, and rolled piece advances reducing mill group temperature 902 ℃, the wire laying temperature of the spiral steel bar: 821 ℃. Final gantry speed: 102 m/s.

Rapidly cooling to 605 ℃ at 5.2 ℃/s in the front half section of the stelmor air-cooled roller way; then cooling to 510 ℃ at the speed of 1.5 ℃/s, and finally cooling to below 354 ℃ at the speed of 0.70 ℃/s for coiling.

Taking 6 groups of mechanical property samples from each rolling batch for tensile test, wherein the mechanical properties are as follows: rel is between 442 and 471MPa, the average value is 459.6MPa, Rm is between 606 and 619MPa, the average value is 612.6MPa, A is between 25 and 29 percent, the average value is 26.8 percent Rm/Rel is between 1.32 and 1.37, the average value is 1.33, and the cold bending percent of pass is 100 percent; aging for three months, wherein the Rel value fluctuation value is 4.2MPa, the Rm value fluctuation value is 3.0MPa, and the welding performance is good; the spiral steel bar structure is as follows: the ferrite and the pearlite account for 100 percent, and the steel bar has an obvious yield platform when being subjected to a tensile test; the maximum performance difference of the same-circle spiral steel bars is 5.3 Pa. Compared with the conventional HRB400E spiral shell, the comprehensive cost is reduced by 19.8 yuan/ton.

Comparative example 3 example of a coil-type steel bar with a low nitrogen content HRB400E

The other conditions are the same as those of the embodiment 3, only the content of the nitrogen component is 41PPm, which is lower than the lower limit of the set range, and the mechanical property detection result is that under the condition that the rolling process parameters are basically consistent: rel is between 395-419MPa, the mean value is 404.4MPa, Rm is between 530-564MPa, the mean value is 543.4MPa, A is between 25-29 percent, the mean value is 28.1 percent Rm/Rel is between 1.32-1.36, the mean value is 1.36, and the cold bending percent of pass is 100 percent; aging for three months, the fluctuation value of Rel value is 11.2MPa, the fluctuation value of Rm value is 7.8MPa, and the welding performance is good. The maximum value of the performance difference of the same coil spiral steel bar is 21.2 MPa.

Example 4

80 tons of blast furnace molten iron and 23 tons of pig iron blocks are respectively added into a 100-ton converter, oxygen blowing smelting is carried out, slagging materials such as lime, sinter ore or ore, fluorite, dolomite and the like are added, when the converter oxygen blowing smelting is carried out for 19min, the converter is turned over, sampling and temperature measuring tapping are carried out, the [ C ] in the molten steel at the end point of the converter is 0.012%, [ Mn ] is between 0.11%, [ O ] is 676PPm, and the tapping temperature is 1609 ℃; slag stopping and tapping, wherein the thickness of a ladle slag layer is 79 mm; when the converter molten steel is discharged to 2/3, ferromanganese alloy, ferrosilicon alloy, rare earth nitrogen alloy, rare earth alloy and recarburizing agent are all added, the ladle is blown and stirred at the bottom of the whole process of tapping, after tapping, nitrogen gas is blown and stirred for 3.5min in an argon station in an atmosphere manner, the stirring is performed for 5min in a soft blowing manner, the temperature is measured, the sampling is performed, and the components of HRB400E disc spiral steel bars are as follows: 0.24 wt% of C, 0.58 wt% of Si, 0.99 wt% of Mn, 0.0107 wt% of N, and 0.0028 wt% of Sigma Re, wherein Sigma Re is the sum of Yb and Y in molten steel, and the argon station leaving temperature is 1603 ℃.

And the ladle long nozzle and the crystallizer submerged nozzle are used for casting protection, and the crystallizer casting powder is alkaline casting powder. Superheat degree of molten steel in continuous casting tundish: 31 ℃; the section size of the continuous casting billet is 165mm multiplied by 165 mm; the continuous casting speed is controlled at 3.8 m/min;

and (3) heating the casting blank, wherein the temperature of a hot soaking section is 1028 ℃, the temperatures of the surface and the core of the steel blank are uniform, and the temperature difference of the section of the same blank is less than 35 ℃. Initial rolling temperature: 965 deg.C. Adopt water-cooling between the frame, set up the water cooling tank before the finishing mill group in advance, the rolled piece advances finishing mill group temperature 921 ℃ in advance, set up the water cooling tank between finish rolling and the finish rolling in advance, the rolled piece advances finishing mill group temperature 892 ℃, sets up the water cooling tank after the finish rolling, and the rolled piece advances reducing mill group temperature 837 ℃, the wire laying temperature of spiral steel bar: 826 ℃ in the presence of oxygen. Final gantry speed: 102 m/s.

Rapidly cooling to 567 deg.C at 4.6 deg.C/s in the front half of stelmor air-cooled roller bed; then cooling to 480 ℃ at the speed of 1.36 ℃/s, and finally cooling to below 390 ℃ at the speed of 0.35 ℃/s for coiling.

Taking 6 groups of mechanical property samples from each rolling batch for tensile test, wherein the mechanical properties are as follows: rel is between 442 and 477MPa, the average value is 457.8MPa, Rm is between 608 and 619MPa, the average value is 610.3MPa, A is between 25 and 29 percent, the average value is 27.4 percent Rm/Rel is between 1.30 and 1.36, the average value is 1.341, and the cold bending percent of pass is 100 percent; aging for three months, wherein the Rel value fluctuation value is 4.2MPa, the Rm value fluctuation value is 3.1MPa, and the welding performance is good; the spiral steel bar structure is as follows: the ferrite and the pearlite account for 100 percent, and the steel bar has an obvious yield platform when being subjected to a tensile test; the maximum value of the performance difference of the same coil of the spiral steel bar is 6.2 MPa. Compared with the conventional HRB400E spiral shell, the comprehensive cost is reduced by 48.9 yuan/ton.

Comparative example 4 example of coiled steel bar with over-high cooling rate HRB400E after rolling

The other conditions are the same as example 4, only after the wire is spun by the spiral shell, the wire is rapidly cooled to 625 ℃ at the speed of 9.0 ℃/s in the front half section of the stelmor air-cooled roller way; then cooling to 546 ℃ at the speed of 4.0 ℃/s, and finally cooling to below 400 ℃ at the speed of 1.75 ℃/s for coiling. The measured mechanical properties are as follows: rel is between 466 and 483MPa, the mean value is 471.1MPa, Rm is between 610 and 623MPa, the mean value is 622.3MPa, and the structure of the steel bar of the spiral is as follows: the total of ferrite and pearlite is about 80%, bainite of about 15% and a small amount of martensite appear, and when the reinforcing steel bar is subjected to a tensile test, an obvious yield platform does not exist, and the performance difference of the same ring is 36.6MPa at most; aging for three months, wherein the fluctuation value of Rel value is 31.6MPa, and the fluctuation value of Rm value is 17.8 MPa. The maximum value of the performance difference of the same coil of spiral steel bars is 31.2 MPa. The organization does not meet the national standard requirements.

Example 5

Adding 135 tons of scrap steel and pig iron blocks into an electric furnace, blowing oxygen, transmitting electricity, smelting, and adding a slagging constituent;

when pig iron and scrap steel are added into an electric furnace, furnace burden such as lime, coke particles or other carburants are added; feeding power, and simultaneously blowing carbon powder and oxygen into the furnace for fluxing; after melting down, decarbonizing, making oxidation slag, dephosphorizing and deslagging; tapping after phosphorus, carbon and temperature of molten steel reach the requirements of steel grades, wherein [ C ] < 0.013%, [ Mn ] < 0.16%, [ O ] < 538PPm and tapping temperature 1615 ℃ are reached in the molten steel at the end point of the electric furnace; tapping at the eccentric bottom, leaving about 30 tons of steel, tapping about 102 tons, and forming a ladle slag layer with the thickness of 38 mm; when the molten steel of the electric furnace is discharged to 2/3, the ferromanganese alloy, the ferrosilicon alloy, the rare earth nitrogen alloy, the rare earth alloy and the recarburizing agent are completely added, the whole bottom of a steel ladle is blown and stirred in the tapping process, after the molten steel is discharged, nitrogen gas is blown in an argon station for stirring for 5min, the temperature is measured, the sampling is carried out, and the components of the HRB400E spiral steel bar are as follows: 0.18 wt% of C, 0.25 wt% of Si, and 0.75 wt% of Mn; the argon station exit temperature is 1576 ℃.

Transferring the molten steel to an LF furnace for sampling, adding a proper slag-making material, properly increasing the amount of bottom-blown argon, blowing off top slag on the surface of the molten steel, then adding a nitriding alloy such as a micro-nitrogen alloy, a rare earth nitrogen alloy and the like according to the components of an electric furnace outlet and the target components, then transmitting electricity for the first time for 6 minutes, simultaneously starting ladle bottom-blown argon stirring, ensuring that the top slag of the ladle covers the liquid level of the molten steel, the molten steel is not exposed, after the first power transmission is finished, adding a micro-alloying element alloy such as a vanadium-containing alloy, a niobium-containing alloy, a titanium-containing alloy or a combined alloy thereof and the like according to the components of the steel entering the LF station and the target components, then transmitting electricity for 8 minutes for the 2 nd time, tapping foamed yellow slag, and discharging HRB400E of an LF refining station, wherein the content of sigma Re is Sc in the molten steel; the exit temperature was 1564 ℃.

And the ladle long nozzle and the crystallizer submerged nozzle are used for casting protection, and the crystallizer casting powder is alkaline casting powder. Superheat degree of molten steel in continuous casting tundish: 24 ℃; the section size of the continuous casting billet is 160mm multiplied by 160 mm; the continuous casting speed is controlled at 4.1 m/min;

and (3) heating the casting blank, wherein the temperature of a hot soaking section is 1018 ℃, the surface temperature and the core temperature of the steel blank are uniform, and the temperature difference of the same blank section is less than 18 ℃. The initial rolling temperature: 952 ℃. The water cooling is adopted between the racks, a water cooling box is arranged in front of the pre-finishing mill group, the temperature of a rolled piece entering the pre-finishing mill group is 925 ℃, the water cooling box is arranged between the pre-finish rolling and the finish rolling, the temperature of the rolled piece entering the finishing mill group is 886 ℃, the water cooling box is arranged after the finish rolling, the temperature of the rolled piece entering the reducing mill group is 805 ℃, and the wire laying temperature of the disc spiral steel bar is: 706 deg.C. Final gantry speed: 118 m/s.

Rapidly cooling to 577 ℃ at 3.5 ℃/s in the front half section of a stelmor air-cooled roller way; then cooling to 475 ℃ at the speed of 1.45 ℃/s, and finally cooling to below 390 ℃ at the speed of 0.55 ℃/s for coiling.

Taking 6 groups of mechanical property samples from each rolling batch for tensile test, wherein the mechanical properties are as follows: rel is between 440 and 478MPa, the average value is 456.1MPa, Rm is between 608 and 625MPa, the average value is 615.9MPa, A is between 25 and 29 percent, the average value is 26.7 percent Rm/Rel is between 1.30 and 1.36, the average value is 1.38MPa, and the cold bending percent of pass is 100 percent; aging for three months, wherein the Rel value fluctuation value is 5.2MPa, the Rm value fluctuation value is 4.5MPa, and the welding performance is good; the spiral steel bar structure is as follows: the ferrite and the pearlite account for 100 percent, and the steel bar has an obvious yield platform when being subjected to a tensile test; the maximum value of the performance difference of the same coil spiral steel bar is 5.6 MPa. The comprehensive cost is reduced by 45.2 yuan/ton compared with the conventional HRB400E spiral shell.

Example 5 the cooling regime was outside the set range.

The other conditions are the same as the example 5, and after the wire is spun by the spiral shell, the wire is rapidly cooled to 645 ℃ at the speed of 1.0 ℃/s in the front half section of the stelmor air-cooled roller way; then cooling to 540 ℃ at the speed of 1.0 ℃/s, and finally cooling to below 389 ℃ at the speed of 0.9 ℃/s for coiling. The measured mechanical properties are as follows: rel is between 395-416MPa, the mean value is 414.1MPa, Rm is between 531-565MPa, and the mean value is 542.2 MPa; the spiral steel bar structure is as follows: the ferrite and the pearlite account for 100 percent, and the steel bar has an obvious yield platform when being subjected to a tensile test, and the performance difference of the same ring is 38.2MPa to the maximum; the performance is low and batches below the national standard requirements occur.

Claims

1. A HRB400E spiral steel bar processed by rare earth and nitrogen microalloying is characterized in that: the HRB400E spiral steel coil comprises the following chemical components in percentage by weight: 0.18-0.25 wt% of C, 0.20-0.60 wt% of Si, 0.8-1.25 wt% of Mn, 0.006-0.0120 wt% of N, Sigma Re0.0015wt% -0.0045 wt% of X, 0.005-0.025 wt% of N, wherein X is selected from V and/or Nb, and the balance of iron and inevitable impurity elements.

2. A rare earth and nitrogen microalloyed processed HRB400E spiral wound steel bar as claimed in claim 1, wherein: when X is selected from V, the weight percentage of X in the HRB400E spiral steel plate is as follows: 0.005 wt% -0.02 wt%, when X is Nb, the weight percentage of X in HRB400E spiral steel is 0.005 wt% -0.020 wt%; when X is selected from V and Nb, the weight percentage of X in HRB400E disc spiral steel bar is 0.005 wt% -0.025 wt%.

3. A rare earth and nitrogen microalloyed processed HRB400E spiral wound steel bar as claimed in claim 1, wherein: the sigma Re is at least one selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Dy, Yb, Y and Sc.

4. The HRB400E spiral reinforcement coil microalloyed by rare earth and nitrogen as claimed in claim 1, wherein: the Rel of the HRB400E spiral steel rod is 435-495MPa, Rm is 595-645MPa, A is 25-35%, Agt is 10-15%, Rm/Rel is 1.31-1.41, and the cold bending qualification rate is 100%; the welding carbon equivalent is less than or equal to 0.45, the aging is carried out for three months, the fluctuation values of Rel and Rm values are less than 10MPa, and the structure of the disc spiral steel bar is as follows: the ferrite and the pearlite account for 100 percent, the performance difference of the same-circle spiral steel bar is less than 10MPa, and the tensile curve has an obvious yield platform.

5. A method of producing a rare earth and nitrogen microalloyed HRB400E spiral wound steel bar as claimed in any one of claims 1 to 4, including the steps of:

step one, smelting molten steel

At least one of blast furnace molten iron, scrap steel, pig iron and reduced iron is taken as an iron-containing raw material, smelting is carried out, a slag former is added, and a silicon-manganese alloy or a ferromanganese alloy, a ferrosilicon alloy, a rare earth nitrogen alloy, a rare earth alloy, a vanadium-nitrogen alloy or a ferrocolumbium alloy and a carburant are added in the tapping process to obtain molten steel according with the designed component content,

step two casting

rolling in step three

step four

And (3) rolling the spiral steel bar obtained in the step three, then controlling and cooling, firstly cooling to 560-630 ℃ at the speed of 2-6 ℃/s, then cooling to 400-550 ℃ at the speed of 1.5-2.2 ℃/s, and finally cooling to below 400 ℃ at the speed of 0.2-0.8 ℃/s to collect and coil to obtain the HRB400E spiral steel bar.

6. A method for producing HRB400E spiral steel bar processed by microalloying rare earth and nitrogen as claimed in claim 5, wherein: in the first step, blast furnace molten iron, or one or two of the blast furnace molten iron and scrap steel or pig iron blocks are added into a converter for oxygen blowing smelting, and a slag former is added, so that the loading of the converter scrap steel is controlled to be 15-30% of the total loading; the end point adopts a high-carbon-drawing-steel pouring process; controlling the end point C of the converter to be 0.06-0.20%; the tapping temperature is 1580 and 1650 ℃; slag stopping and tapping are carried out, and the thickness of a slag layer of a steel ladle is less than or equal to 100 mm; according to the requirements of the terminal components of the converter and the components of HRB400E spiral steel bars, silicon-manganese alloy or ferromanganese alloy, silicon-iron alloy, rare earth nitrogen alloy, rare earth alloy, vanadium-nitrogen alloy and carburant are added before molten steel is discharged to 2/3, the ladle is blown at the bottom in the whole tapping process and stirred, argon or nitrogen is blown in an argon station after steel is discharged and stirred for 4-12min, then temperature measurement and sampling are carried out, the components of the HRB400E spiral steel bars are adjusted to target values, and the temperature of the argon station is controlled to be between 1555 ℃ and 1610 ℃.

7. A method for producing HRB400E spiral steel bar processed by microalloying rare earth and nitrogen as claimed in claim 5, wherein: in the first step, scrap steel and pig iron blocks or reduced iron are used as iron-containing raw materials, oxygen blowing and power transmission smelting are added into an electric furnace, a slag former is added, molten steel C at the end point of the electric furnace is controlled to be 0.10-0.20%, steel is retained, the steel quantity is 1/3% of the total molten steel quantity, and eccentric bottom tapping is carried out; the tapping temperature is 1570-; transferring the molten steel to an LF furnace for sampling, adding a slag making material, properly increasing the amount of bottom-blown argon, blowing off top slag on the surface of the molten steel, then adding a nitriding alloy according to the outbound components and the target components of the electric furnace, then carrying out power transmission for 3-7 minutes for the first time, and simultaneously starting ladle bottom-blown argon stirring to ensure that the top slag of the ladle covers the liquid level of the molten steel and the molten steel is not exposed; after the first power transmission is finished, microalloying element alloy is added according to the components entering the LF station and the target components, then the 2 nd power transmission is carried out for 5-10 minutes, the foamed yellow slag is produced and tapped, the components reach the target components of the HRB400E disc spiral steel bar, and the outlet temperature is 1550 ℃ to 1610 ℃.

8. A method for producing HRB400E spiral steel bar processed by microalloying rare earth and nitrogen as claimed in claim 5, wherein: smelting by adopting a double-station ultrahigh-power quantum electric furnace, preheating waste steel by using electric furnace smoke and adopting a continuous waste steel adding process; the electric furnace adopts at least one of a furnace door carbon-oxygen spray gun and a furnace wall oxygen gun to input chemical heat.

9. A method for producing HRB400E spiral steel bar processed by microalloying rare earth and nitrogen as claimed in claim 5, wherein: the pouring process adopts a ladle long nozzle and a crystallizer immersion nozzle for protection pouring, the crystallizer protection slag adopts alkaline protection slag, and the superheat degree of the tundish molten steel is continuously poured: 15-30 ℃; the section size of the continuous casting billet is 180mm multiplied by 150mm and 180mm multiplied by 150 mm; the continuous casting speed is controlled at 2.5-4.5 m/min.

10. A method for producing HRB400E spiral steel bar processed by microalloying rare earth and nitrogen as claimed in claim 5, wherein: when the continuous casting billet is heated, the temperature of the thermal soaking section is 1000-1160 ℃, and the temperature difference of the section of the continuous casting billet is less than 40 ℃.