CN112553406B - Steel plate and control method of content of B element in steel - Google Patents

Steel plate and control method of content of B element in steel Download PDF

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CN112553406B
CN112553406B CN202011407491.3A CN202011407491A CN112553406B CN 112553406 B CN112553406 B CN 112553406B CN 202011407491 A CN202011407491 A CN 202011407491A CN 112553406 B CN112553406 B CN 112553406B
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steel
content
molten steel
controlled
equal
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CN112553406A (en
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周剑丰
邓必荣
罗钢
齐江华
谢世正
肖爱达
董常福
刘彭
陈杰
余强
谭大进
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Lysteel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

The application relates to a steel plate and a method for controlling the content of B element in the steel, which comprises the following steps: adding scrap steel, molten iron and substances for alloying before converter blowing, and carrying out converter blowing in a blowing mode corresponding to the type of steel; tapping when the converter end point meets the tapping requirement, and adding ferrosilicon and silicomanganese alloy into the tapped molten steel for alloying and deoxidation; and after the deoxidation, performing LF refining, and adding aluminum for deoxidation in the LF refining. The method for controlling the content of the B element in the steel can effectively control the content of the B element in a finished product.

Description

Steel plate and control method of content of B element in steel
Technical Field
The application belongs to the technical field of metallurgy, and particularly relates to a steel plate and a method for controlling the content of an element B in the steel.
Background
In order to increase the service performance and the process performance of steel, alloy raw materials are usually added into the steel for alloying, but the alloy raw materials usually contain boron B element; on one hand, the B element is easy to be aggregated at the grain boundary, thereby bringing some adverse effects on the impact property of steel; on the other hand, the B element and N, O and other elements in the steel form compounds, which can also cause some influences on the mechanical property and the welding property of the steel; therefore, the content of B element needs to be controlled in the steel-making process.
Disclosure of Invention
In view of the above, the present application aims to provide a steel plate and a method for controlling the content of B element in steel, so as to solve the technical problem that B element of the steel plate produced by the existing smelting process cannot meet the production requirement.
In order to achieve the above object, a first aspect of embodiments of the present application provides a method for controlling the content of B element in steel, including the steps of: adding scrap steel, molten iron and substances for alloying before converter blowing, and carrying out converter blowing in a blowing mode corresponding to the type of steel; tapping when the converter end point meets the tapping requirement, and adding ferrosilicon and silicomanganese alloy into the tapped molten steel for alloying and deoxidation; and after the deoxidation, performing LF refining, and adding aluminum for deoxidation in the LF refining.
Optionally, the LF refining further comprises adding lime;
correspondingly, the LF refining step comprises the following steps:
adding aluminum and lime, wherein the bottom blowing argon flow in the power transmission process is less than or equal to 300L/min, the bottom blowing argon flow in the slagging process is less than or equal to 800L/min, the molten steel is deoxidized well in the refining process to produce reductive refined slag, adding alloy into the molten steel to adjust the components of the molten steel, and performing a calcium treatment process after the components of the molten steel are adjusted well, wherein the bottom blowing flow in the calcium treatment process is 100L/min-300L/min, and the subsequent soft bottom blowing argon flow is 80L/min-120L/min.
Optionally, the adding amount of lime is controlled to be 1500 Kg-2000 Kg.
Optionally, the step of tapping comprises:
tapping is carried out by adopting slag blocking or steel retaining operation so as to retain boron oxide formed by smelting in a converter.
Optionally, the adding proportion of the molten iron and the scrap steel is controlled to be 170-175: 50-60.
Optionally, the substances used for alloying include nickel iron and ferrochrome.
Optionally, the slag line brick steel ladle residual molten steel is added in converter blowing, the content of the B element of the steel ladle slag line brick is controlled to be less than or equal to 0.03 percent, the content of the B element of manganese-silicon alloy is controlled to be less than or equal to 0.015 percent, the content of the B element of nickel-iron is controlled to be less than or equal to 0.0007 percent, and the content of the B element of ferrochrome is controlled to be less than or equal to 0.004 percent.
According to a second aspect of the embodiments of the present application, a steel plate is provided, and the content of B in the steel plate is controlled by using the method for controlling the content of B element in the steel.
Compared with the prior art, the embodiment of the application has the following beneficial effects:
on one hand, the embodiment of the application utilizes the characteristic that B element is easy to combine with O element, changes the adding mode of the alloy, adds the substance for alloying before the converter blowing for alloying, and fully utilizes the oxidizing atmosphere in the converter blowing process to remove the B element brought by the substance for alloying; on the other hand, after tapping, the contents of silicon and manganese in the molten steel are adjusted, and aluminum is added for deep deoxidation treatment in LF refining, so that the higher oxygen content in the molten steel before aluminum addition can be ensured, the higher oxygen content in the molten steel is utilized to react with the B element in the molten steel, the reaction time is sufficient, and the content of the B element in the molten steel can be further reduced.
Detailed Description
The following detailed description describes embodiments of the present application, which are exemplary and are intended to be illustrative of the present application and are not to be construed as limiting the present application.
The content of the B element in the pipeline steel and the bridge steel products is strict, and the content of the B element is generally regulated to be not more than 0.0005 percent, so that the smelting process needs to be controlled for controlling the content of the B element.
For example, the process for preparing the pipeline steel comprises the following steps: molten iron pretreatment, converter smelting, LF refining, continuous casting process, rolling and other processes.
Wherein, converter smelting includes: determining the addition amount of molten iron and scrap steel in the converter according to the temperature and the components of the molten iron; when the steel of the previous furnace is not smelted, the information of the molten iron entering the next furnace is mastered, and the steel-making coolant and the slagging material of the next furnace are configured; after the blowing of the previous furnace is finished, main materials of the next furnace, such as molten iron and scrap steel, are added into the converter, the scrap steel is added firstly, then the molten iron is added, after the main materials are added, the furnace body is shaken up, oxygen blowing is started, a slag former is added, and the lance position, the oxygen blowing flow and the like are adjusted according to the conditions of flame at the furnace mouth and the like in the blowing process; in the later stage of converting, the converting condition in the furnace is judged according to the information such as flame at the furnace mouth, if the temperature and the components of the molten steel meet the tapping standard, tapping is carried out, otherwise, oxygen is blown in again, and a certain amount of slag former or coolant is added according to the detection result of the molten steel; when the temperature and the components of the molten steel meet the tapping requirements, pouring the molten steel into a steel ladle; after tapping, the furnace body is shaken up, and nitrogen gas is blown into a hearth to splash slag for protecting the furnace; and adding alloy elements and an oxidant to carry out alloying and deoxidation.
The applicant found that the above process cannot effectively control the content of B element in steel, and that the affinity of B element to O element is higher than that of C, Mn but lower than that of Si, Al, Ti element to O element under the condition of molten steel smelting.
The N element existing in the steel can almost form nitrides with other elements in the steel, the affinity of the Ti element and the N element is strongest, and the affinity of the Al element and the N element is only second to the affinity of the Ti element and the N element but is stronger than the affinity of the B element and the N element. At the temperature of smelting molten steel, the elements such as Mn, Si, Ti and Al do not form solid boride. During smelting, residual B elements in molten steel and B-containing elements in materials in contact with the molten steel can enter the molten steel, the molten steel hardly contains Si, Al and Ti elements in the converter smelting process, the content of O in the molten steel is high, and B elements and O, N elements in the molten steel form oxides and nitrides respectively.
In order to solve the problem that the increase of B in molten steel causes the unqualified finished steel, the embodiment of the application provides a method for controlling the content of B element in the steel, which comprises the following steps:
s100, blowing in a converter;
adding scrap steel, molten iron and substances for alloying before blowing in a converter, smelting in a blowing mode corresponding to the type of steel, and enabling B element in the molten steel to form boron oxide in an oxidizing atmosphere; tapping when the converter end point meets the tapping requirement, and adding ferrosilicon and silicomanganese alloy into the tapped molten steel for alloying and deoxidation;
and after tapping, aluminum is not added into the molten steel for deoxidation, so that a certain oxygen content in the molten steel can be maintained, the B element in the molten steel and oxygen can fully react to form boron oxide, and sufficient oxidation time can be provided for the B element.
S200, LF refining;
and (4) performing LF refining after deoxidation, and adding aluminum for deoxidation in the LF refining.
According to the embodiment of the application, on one hand, the characteristic that B element is easy to combine with O element is utilized, the adding mode of the alloy is changed, the alloying substance is added before the converter is blown for alloying, and the B element brought by the alloying substance and the B element remained in the molten steel are removed by fully utilizing the oxidizing atmosphere in the converter blowing process; on the other hand, after tapping, the contents of silicon and manganese in the molten steel are adjusted, and aluminum is added for deep deoxidation treatment in LF refining, so that the higher oxygen content in the molten steel before aluminum addition can be ensured, the higher oxygen content in the molten steel is utilized to react with the B element in the molten steel, the reaction time is sufficient, and the content of the B element in the molten steel can be further reduced.
As a preferred example, boron oxides formed from substances for alloying and the like are taken into the converter slag, and when the converter is tapped, tapping may be performed using a slag-stopping or steel-retaining operation to retain the converter slag, reduce the amount of the converter slag containing B elements poured into a ladle into an LF refining process, and prevent the boron oxides contained in the converter slag from being reduced into molten steel in the LF refining process. It will be understood that the substances used for alloying are related to the composition of the steel grade, for example in order to regulate the Ni content, Cr content, etc. in the steel grade, and may be chosen from the group comprising ferronickel and ferrochrome, which are non-oxidizable substances, which are fed into the converter before the converter smelting, in which oxidizing atmosphere the B elements introduced by the ferronickel and ferrochrome themselves are removed. And when the materials of the ferronickel and the ferrochrome are selected, the alloy with low B content is selected, and the content of the B element is controlled from the source.
More preferably, in the step of LF refining, lime is added, the temperature is adjusted by power transmission, the components are adjusted by alloy, the components of molten steel are sampled and detected, calcium treatment is carried out to spheroidize inclusions, and the cleanliness of the molten steel is purified by soft argon blowing; the bottom blowing argon flow in the power transmission process can be controlled to be less than or equal to 300L/min, the bottom blowing argon flow in the slagging process is controlled to be less than or equal to 800L/min, the molten steel in the LF refining process is deoxidized well to produce reductive refining slag, alloys such as ferrosilicon, silicomanganese, aluminum particles and the like are added to adjust the components of the molten steel, a calcium treatment process is carried out after the components of the molten steel are adjusted well, the bottom blowing argon flow in the calcium treatment process is 100L/min-300L/min, the subsequent bottom blowing argon flow in the soft blowing process is 80L/min-120L/min, the argon of the steel ladle is forbidden to be stirred greatly after alloying, the power transmission and the temperature rise are forbidden, and slag materials are added into the steel ladle. The addition amount of lime is controlled to be 1500 Kg-2000 Kg, which can ensure that the refining slag has good capacity of boron oxide; and each bottom blowing flow in the LF refining process and the LF refining time are controlled, so that the good reducing atmosphere of the LF refining can be ensured, boron oxide in refining slag in the LF refining process can be prevented from being reduced in the good reducing atmosphere of the LF refining, the increase of B in molten steel in the LF refining process is reduced, and the condition that the alloying in the LF refining process is carried out until the alloying is carried out to obtain B elements with the content of less than 0.0003 percent is ensured. A certain amount of slag is ensured in the LF refining process, and deoxidation and alloying are carried out in the LF refining process, so that the requirement on the cleanliness of molten steel is met.
Preferably, the LF is refined and then enters a continuous casting process, the continuous casting tundish adopts a submerged nozzle for protection pouring, and the low-carbon alkaline covering agent prevents the molten steel from secondary oxidation and reduces the oxygen content of the molten steel to the maximum extent. And (3) uniformly distributing the B content in the casting blank by adopting an electromagnetic stirring process, and rolling the continuous casting slab after the continuous casting slab is placed into the slow cooling pit.
The materials contacting with the molten steel, such as alloy, refractory and ladle slag line brick, contain B element, and the addition of the materials in the molten steel is also one of the main reasons for increasing B content in the molten steel. The original content detection of B of the material in contact with the molten steel is mastered, and the material with low B content is used when an extremely low B product is smelted, so that the source of increasing B elements is reduced. According to the content of B element detected by sampling the material contacted with molten steel, the content of B element is found to be greatly different from that of the alloy of different manufacturers of the same brand, B content detection is carried out on the material contacted with the molten steel provided by A, B suppliers, and the detection result is shown in Table 1:
TABLE 1
Figure BDA0002819002260000051
In combination with table 1, it can be seen that the content of B element in the material supplied from supplier a and coming into contact with molten steel is low, and the material supplied from supplier a can be selected. Therefore, in order to smelt the low B element steel, the content of B in the ladle slag line brick can be controlled to be lower than 0.03 percent.
The present application is further illustrated by the following specific examples
In the following examples or comparative examples, unless otherwise specified, the methods and apparatuses used in the examples or comparative examples are those conventional in the art, and the raw materials used are all conventional commercially available raw materials.
Example 1
The smelting steel grade is Q345QENH, and the steel grade has the following composition requirements: c: 0.05-0.010%, Mn: 1.0-1.25%, Cr: 0.35-0.55%, Ni: 0.35 to 0.45 percent, B is less than or equal to 0.0005 percent, N is less than or equal to 0.0045 percent, and H is less than or equal to 0.0002 percent.
The preparation method of the Q345QENH steel grade comprises the following steps:
170 tons of molten iron and 60 tons of scrap steel are loaded into a converter, 2600Kg of ferronickel and low-carbon ferrochrome alloy are added into the converter together with the scrap steel for blowing before smelting in the converter, smelting is carried out according to the blowing mode of steel types, the steel retaining operation is adopted in the tapping process when the terminal point of the converter is properly controlled, the converter is controlled to discharge slag, and the thickness of the steel ladle slag is not more than 55 mm.
And adopting slag line brick steel ladles of A suppliers to carry out steel ladle residue molten steel. After the tapping operation is finished, ferrosilicon and silicomanganese alloy are added into the molten steel for alloying.
After deoxidation, the molten steel enters an LF refining process, aluminum deoxidation and lime are added in batches, the total addition amount of the lime is controlled to be about 1800Kg, the bottom blowing argon flow in the power transmission process is controlled to be less than or equal to 300L/min, the bottom blowing argon flow in the slagging process is controlled to be less than or equal to 800L/min, alloy adjusting components are added into the molten steel, aluminum is added in batches in the process, the calcium treatment bottom blowing flow is controlled to be 200L/min, the soft blowing flow is controlled to be 100L/min, and the refining smelting time is 70 min;
and entering a continuous casting process after the LF refining process is finished.
Q345QENH the control of the [ B ] of the finished molten steel is shown in Table 2.
Example 2
Smelting steel grade is Q690QD, and this steel grade composition requires: c: 0.10-0.14%, Mn: 1.0-1.25%, Cr: 0.40-0.55%, Ni: 0.30 to 0.45 percent, B is less than or equal to 0.0005 percent, N is less than or equal to 0.0040 percent, and H is less than or equal to 0.0002 percent.
175 tons of converter molten iron and 50 tons of scrap steel are adopted, 2200Kg of ferronickel and low-carbon ferrochrome alloy are added into a scrap steel groove and are added into a converter together with the scrap steel for converting before smelting, smelting is carried out according to the converting mode of steel types, when the terminal point of the converter is properly controlled, steel retaining operation is adopted in the tapping process, the converter is controlled to discharge slag, and the thickness of ladle slag is not more than 50 mm.
And adopting slag line brick steel ladles of A suppliers to carry out steel ladle residue molten steel. And after the tapping operation is finished, adding ferrosilicon and silicomanganese into the molten steel for alloying.
After the deoxidation is finished, the molten steel enters an LF refining process, lime and aluminum are added in batches, the total addition amount of the lime is controlled to be about 1500Kg, the power transmission flow is controlled to be less than or equal to 300L/min, the slagging flow is controlled to be less than or equal to 800L/min, alloys such as silicon, manganese and the like are added into the molten steel to adjust components, the bottom blowing flow of calcium treatment is controlled to be 200L/min, the soft blowing flow is 100L/min, and the refining smelting time is 59 min;
and after the LF refining process is finished, entering a continuous casting process.
Q690QD control [ B ] of finished molten steel is shown in Table 2.
Comparative example 1
An effective control method for the content of B element in steel is disclosed, wherein the smelting steel type is Q345QENH, 160 tons of converter molten iron and 65 tons of scrap steel are adopted, smelting is carried out according to the blowing mode of the steel type, the converter is controlled to discharge slag in the tapping process when the end point of the converter is properly controlled, and the measured slag thickness is 65 mm.
And adopting slag line brick steel ladles of a supplier B to ladle residual molten steel. Ferronickel, ferromanganese, ferrosilicon and the like are alloyed in the tapping process, slag line brick steel ladles of a supplier B are used for receiving molten steel, and aluminum is added and silicon-manganese alloy of a supplier A is used for deoxidation and alloying after tapping.
After the deoxidation is finished, the molten steel enters an LF refining process, lime and aluminum are added in batches, the total addition amount of the lime is controlled to be about 1200Kg, the power transmission flow is controlled to be less than or equal to 300L/min, the slagging flow is controlled to be less than or equal to 800L/min, alloy adjusting components are added into the molten steel, the bottom blowing flow of calcium treatment is controlled to be 200L/min, the soft blowing flow is 100L/min, and the refining time is 82 min;
and after the LF refining process is finished, entering a continuous casting process.
Q345QENH the control of the [ B ] of the finished molten steel is shown in the table 2.
Comparative example 2
An effective control method for B element content in steel is characterized in that smelting steel is Q690QD, 160 tons of converter molten iron and 65 tons of scrap steel are adopted for smelting according to a blowing mode of the steel, the converter is controlled to be suitable for end point control when the converter is properly controlled, converter roughing is controlled in the tapping process, and the slag thickness is measured to be 80 mm.
And adopting slag line brick steel ladles of a supplier B to ladle residual molten steel. Ferronickel, ferromanganese, ferrosilicon, aluminum and the like are alloyed in the tapping process, a slag line brick steel ladle of a supplier B is adopted for receiving molten steel, and aluminum is added and silicon-manganese alloy of a supplier A is adopted for deoxidation and alloying after tapping.
After the deoxidation is finished, the molten steel enters an LF refining process, lime is added in batches, the total addition amount is controlled to be about 1200Kg, the power transmission flow is controlled to be less than or equal to 300L/min, the slagging flow is controlled to be less than or equal to 800L/min, alloy is added into the molten steel to adjust components, the bottom blowing flow of calcium treatment is controlled to be 200L/min, the soft blowing flow is 100L/min, and the refining smelting time is 109 min;
and entering a continuous casting process after the LF refining process is finished.
Q690QD control [ B ] of finished molten steel is shown in Table 2.
TABLE 2
Figure BDA0002819002260000081
The B content of the finished molten steel in the comparative examples 1-2 is 0.0007 percent respectively, the production requirement is not met, and the B content is required to be controlled to be not more than 0.0005 percent; on the other hand, the content of B in the finished molten steel in the embodiments 1 to 2 is 0.0002% and 0.0003%, respectively, and meets the production requirements, so that the content of B can be effectively controlled by adopting the scheme of the embodiment of the application.
The elements such as C, Fe, Mn, Si, Al, B and the like in the molten steel are deoxidizing elements, and the equations of the reaction of the elements with [ O ] in the molten steel are shown in formulas (1) to (6):
[C]+[O]＝CO △Gθ ＝-20 490-39.17T (1)
[Fe]+[O]＝FeO △Gθ ＝-112 442+46.56T (2)
[Mn]+[O]＝MnO △Gθ ＝-244 330+107.6T (3)
[Si]+2[O]＝SiO 2 △Gθ ＝-288 220+109.1T (4)
2[Al]+3[O]＝Al 2 O 3 △Gθ ＝-408 333+131.3T (5)
2[B]+3[O]＝B 2 O 3 △Gθ ＝-254 806.5+95.5T (6)
the sequence of the above reaction is Al > C > Si > B > Mn > Fe, i.e. the deoxidation sequence of the elements is Al > C > Si > B > Mn > Fe. According to the oxidizing capability of each element in the smelting process, the steel grades of the embodiments 1 and 2 are smelted, and the content of the B element in the steel grades is controlled in the embodiments 1-2 through the following aspects, on the one hand, the amount of molten iron is increased, the amount of scrap steel is reduced, and the source of the B element in a molten iron raw material belt is controlled; secondly, adding ferronickel, ferrochrome and other alloys which are difficult to oxidize before smelting in a converter, controlling slag discharging during converter tapping, and reducing the flow of converter slag containing B elements into the next working procedure by adopting steel retention operation to influence the content of B in molten steel; thirdly, the ladle slag line brick is corroded greatly, and the content of B in the final finished product steel is controlled by controlling the content of B in the ladle slag line brick; fifthly, in the LF refining process, proper bottom blowing flow and refining time control are adopted to prevent boron oxide in the refining slag from being reduced; in the sixth aspect, a certain amount of refining slag such as lime is added in the LF refining process, so that the refining slag has good capacity of accommodating boron oxide; and in the seventh aspect, ferrosilicon and silicomanganese alloy are added into the converter tapping steel, and aluminum is added for strong deoxidation in the LF refining process, so that a certain oxygen content in the molten steel in the converter smelting process can be ensured for oxidizing the B element, and sufficient time is provided for oxidizing.
The above description is only a preferred embodiment of the present application and should not be taken as limiting the present application, and any modifications, equivalents and improvements made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (7)

1. A method for controlling the content of B element in steel is characterized by comprising the following steps:
adding scrap steel, molten iron and substances for alloying before converter blowing, and carrying out converter blowing in a blowing mode corresponding to the type of steel;
tapping when the converter end point meets the tapping requirement, and after tapping, not adding aluminum into the molten steel for deoxidation so as to enable the B element in the molten steel to fully react with oxygen to form boron oxide, and adding ferrosilicon and silicomanganese alloy into the molten steel after tapping for alloying and deoxidation;
after deoxidation, the LF refining is carried out, aluminum is added for deoxidation in the LF refining,
wherein the steel comprises the following components:
c: 0.05-0.010%, Mn: 1.0-1.25%, Cr: 0.35-0.55%, Ni: 0.35 to 0.45 percent of the total weight of the alloy, less than or equal to 0.0005 percent of B, less than or equal to 0.0045 percent of N, and less than or equal to 0.0002 percent of H; or
C：0 .10％～0 .14％，Mn：1 .0％～1 .25％，Cr：0.40％～0.55％，Ni：0.30％～0.45％，B≤0.0005％，N≤0.0040％，H≤0.0002％。
2. The method for controlling the content of the element B in the steel according to claim 1, wherein the LF refining further comprises the steps of adding lime;
correspondingly, the LF refining step comprises the following steps:
adding aluminum and lime, wherein the flow of bottom-blown argon is less than or equal to 300L/min in the power transmission process, the flow of bottom-blown argon is less than or equal to 800L/min in the slagging process, deoxidizing molten steel in the refining process to well produce reductive refined slag, adding alloy into the molten steel to adjust the components of the molten steel, and performing a calcium treatment process after the components of the molten steel are well adjusted, wherein the flow of bottom-blown argon in the calcium treatment process is 100L/min-300L/min, and the flow of subsequent bottom-blown argon in soft blowing is 80L/min-120L/min.
3. The method for controlling the content of the B element in the steel according to claim 2, wherein the addition amount of lime is controlled to be 1500-2000 Kg.
4. The method for controlling the content of B element in steel according to claim 1, wherein the step of tapping comprises:
tapping is carried out by adopting slag blocking or steel retaining operation so as to retain boron oxide formed by converter blowing.
5. The method for controlling the content of the element B in the steel according to claim 1, wherein the adding ratio of the molten iron to the scrap steel is controlled to be 170-175: 50-60.
6. The method of controlling the content of element B in steel according to claim 1, characterized in that the substances for alloying include ferronickel and ferrochrome.
7. The method for controlling the content of the element B in the steel according to claim 6, wherein the slag line brick steel ladle residual molten steel is added in the converter blowing, the content of the element B in the slag line brick of the steel ladle is controlled to be less than or equal to 0.03%, the content of the element B in the manganese-silicon alloy is controlled to be less than or equal to 0.015%, the content of the element B in the nickel-iron is controlled to be less than or equal to 0.0007%, and the content of the element B in the ferrochrome is controlled to be less than or equal to 0.004%.
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