CN109652741B - Grain-oriented pure iron and production method thereof - Google Patents

Grain-oriented pure iron and production method thereof Download PDF

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CN109652741B
CN109652741B CN201910119972.5A CN201910119972A CN109652741B CN 109652741 B CN109652741 B CN 109652741B CN 201910119972 A CN201910119972 A CN 201910119972A CN 109652741 B CN109652741 B CN 109652741B
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temperature
pure iron
grain
rolling
oriented pure
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CN109652741A (en
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王海军
仇圣桃
荣哲
项利
付兵
赵芃
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Zhong Da National Engineering And Research Center Of Continuous Casting Technology Co ltd
Anhui University of Technology AHUT
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Zhong Da National Engineering And Research Center Of Continuous Casting Technology Co ltd
Anhui University of Technology AHUT
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D3/00—Diffusion processes for extraction of non-metals; Furnaces therefor
    • C21D3/02—Extraction of non-metals
    • C21D3/04—Decarburising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
    • C21D8/1222—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
    • C21D8/1233—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2201/00—Treatment for obtaining particular effects
    • C21D2201/05—Grain orientation

Abstract

The invention discloses grain-oriented pure iron and a production method thereof, belonging to the technical field of electrical steel. The invention relates to grain-oriented pure iron, which comprises the following components in percentage by mass: n: 0.005-0.0125%, Als: 0.007-0.035%. And the mass percentage relationship between Als and N is as follows: Als/N is 2-6. The invention relates to a production method of grain-oriented pure iron, which comprises converter smelting, continuous casting, hot rolling, normalizing, cold rolling and annealing; wherein the mass percentages of N and Als in the plate blank obtained after continuous casting are respectively as follows: n: 0.005-0.0125%, Als: 0.007-0.035%. The invention aims to overcome the defect of low magnetic induction intensity of grain-oriented pure iron in the prior art, and provides the grain-oriented pure iron and the production method thereof.

Description

Grain-oriented pure iron and production method thereof
Technical Field
The invention relates to the field of electrical steel, in particular to grain-oriented pure iron and a production method thereof.
Background
The electric steel is also called silicon steel sheet, is an important soft magnetic alloy indispensable for the industries of electric power, electronics and military, is a metal functional material with the largest output, and is mainly used as iron cores of various motors, generators and transformers. The production process is complex, the manufacturing technology is strict, and foreign production technologies are protected in a patent form and are regarded as the lives of enterprises. The manufacturing technology and product quality of electrical steel sheets are one of the important marks for measuring the production and technological development level of national special steel. At present, the quantity, quality and specification grade of cold-rolled electrical steel in China cannot meet the requirement of energy (power) industrial development, and the cold-rolled electrical steel has a larger gap in the aspects of production technology, equipment, management, scientific research and the like compared with Japan.
The grain oriented pure iron is an electric pure iron with sharp preferred orientation formed by the combination of proper inhibitor collocation, reasonable plastic working and strict heat treatment and by developing secondary recrystallization, the crystal grains are arranged along the rolling direction according to the (110) [001] position, and the iron is an electric steel with special application. The production technology of grain-oriented pure iron suitable for industrial production has been developed in Japan and America, and is successfully applied to the manufacture of electrical equipment and basic scientific research equipment. At present, the literature mainly reports examples in scientific research and production of grain-oriented pure iron, the magnetic property B800= 1.80-1.91T, the patent B800 of only new-day iron reaches 1.92-2.03T, and the improvement space is still larger compared with the saturation magnetic induction of pure iron of 2.16T (the theoretical saturation magnetic induction of pure iron). After the self-wearing of Mr. China, the research on the oriented pure iron is basically in a blank state. Therefore, how to develop grain-oriented pure iron with high magnetic induction intensity is a problem to be solved urgently in the prior art.
Through search, some solutions are also proposed in the prior art, such as the invention and creation names: a grain-oriented pure iron manufactured by a one-time cold rolling method and a method thereof (application date: 2016-07-11; application number: 201610543448.7) disclose a grain-oriented pure iron manufactured by a one-time cold rolling method and a method thereof. The method comprises the following steps: converter smelting → refining of molten steel by a vacuum circulation degassing method → continuous casting → heating of a plate blank → hot rolling → normalizing → cold rolling → annealing, wherein: after the continuous casting step, the obtained continuous casting slab comprises the following components in percentage by mass: 0.01 to 0.08%, Si: 0.01 to 1.0%, Mn: 0.05-0.5%, P: 0.01-0.1%, S: 0.003-0.01%, Als: 0.005-0.05%, N: 0.005-0.02%, Cu: 0.05-0.8% of iron, and the balance of inevitable impurities and Fe; in the hot rolling step, controlling the content of the gamma-phase obtained in the finish rolling to be 10-30% by mass percent; the normalizing step is to preserve heat for 30-600 s at 650-800 ℃; the annealing step includes decarburization annealing and high temperature annealing. Therefore, the oriented pure iron with high saturation magnetic induction intensity and sharp {110} preferred orientation can be obtained by utilizing the traditional thick slab production process. However, this solution has a disadvantage in that the magnetic induction of the actual grain-oriented pure iron is not high. In summary, how to develop grain-oriented pure iron with high magnetic induction intensity is a problem to be solved urgently in the prior art.
Disclosure of Invention
1. Technical problem to be solved by the invention
The invention aims to overcome the defect of low magnetic induction intensity of grain-oriented pure iron in the prior art, and provides the grain-oriented pure iron and the production method thereof.
2. Technical scheme
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
the invention relates to grain-oriented pure iron, which comprises the following components in percentage by mass: n: 0.005-0.0125%, Als: 0.007-0.035%.
As a further improvement of the invention, the mass percentage relationship of Als and N in the grain-oriented pure iron is as follows: Als/N =2~ 6.
As a further improvement of the invention, the mass percentages of Si and Mn elements are as follows: si: 0-0.1%, Mn: 0 to 0.1%.
As a further improvement of the invention, the grain-oriented pure iron comprises the following chemical components in percentage by mass: c: 0.02 to 0.04%, Si: 0-0.1%, Mn: 0-0.1%, S <0.005%, Als: 0.007-0.035%, N: 0.005-0.0125% of Fe, and the balance of inevitable impurities and Fe.
The invention relates to a production method of grain-oriented pure iron, which comprises converter smelting, continuous casting, hot rolling, normalizing, cold rolling and annealing; wherein the mass percentages of N and Als in the plate blank obtained after continuous casting are respectively as follows: n: 0.005-0.0125%, Als: 0.007-0.035%.
As a further improvement of the invention, the hot rolling comprises rough rolling and finish rolling; the initial rolling temperature of rough rolling is 1100-1120 ℃, and the final rolling temperature is 950-1000 ℃; the initial rolling temperature of finish rolling is 1050-1100 ℃, and the final rolling temperature is 880-900 ℃.
As a further improvement of the invention, the normalizing comprises high-temperature stage normalizing and low-temperature stage normalizing; the temperature of the high-temperature section is 850-1100 ℃, and the temperature of the low-temperature section is 600-800 ℃.
As a further improvement of the invention, the cold rolling comprises the following specific steps: and rolling the plate blank to 0.3mm in three or six passes.
As a further improvement of the present invention, the annealing includes decarburization annealing; the protective gas for decarburization annealing is a mixed gas of nitrogen and hydrogen, and the volume percentages of the nitrogen and the hydrogen in the mixed gas are respectively as follows: n is a radical of2：55~75%，H2：25~45%。
The invention is further improved by coiling the steel between hot rolling and normalizing, wherein the coiling temperature is 480-500 ℃.
3. Advantageous effects
Compared with the prior art, the technical scheme provided by the invention has the following remarkable effects:
(1) the invention relates to grain-oriented pure iron, wherein the mass percentage relationship of N and Als is as follows: Als/N =2~ 6. When N and Al satisfy the relational expression, a certain amount of AlN can be generated, and the relative content of N and Al is limited, so that the magnetic induction intensity of the grain-oriented pure iron can be improved, and the harm caused by the increase of the Al content can be further reduced;
(2) the grain-oriented pure iron comprises the following components in percentage by mass: 0-0.1%, and a proper amount of silicon can coarsen crystal grains, improve texture and improve the magnetism and magnetic permeability of the crystal grain oriented pure iron;
(3) according to the production method of the grain-oriented pure iron, after decarburization and annealing are carried out on a grain-oriented pure iron slab, sub-grains with the {110} <001> orientation existing between the {111} <112> deformation zones can be preferentially gathered to form Goss orientation grains, and the low-energy-storage {100} sub-grains are not easy to recrystallize due to low energy storage, so that the magnetic permeability of the grain-oriented pure iron is further improved;
(4) according to the production method of the grain-oriented pure iron, the cold rolling reduction is large, the shearing stress borne by the plate blank is large, the texture of the plate blank is further changed, and the strong { 113-115 } <110> texture appears in the plate blank. Therefore, the grain-oriented pure iron finally forms the cold rolling texture type of {001} <110>, {112} <110>, { 113-115 } <110>, {111} <112>, so that the magnetic induction intensity of the grain-oriented pure iron is further improved;
(5) according to the production method of the grain-oriented pure iron, disclosed by the invention, the slab is subjected to secondary annealing, so that the development of secondary recrystallization and the purification and removal of an inhibitor are promoted, and the magnetic induction intensity of the grain-oriented pure iron is further improved.
Drawings
FIG. 1 is a flow chart of a method for producing grain-oriented pure iron according to the present invention;
fig. 2 is a diagram of a secondary annealing process of example 1;
FIG. 3 is a diagram of a precipitated phase of pure AlN with a grain orientation according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments; moreover, the embodiments are not relatively independent, and can be combined with each other according to needs, so that a better effect is achieved. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
For a further understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings and examples.
Referring to fig. 1 to 3, in the grain-oriented pure iron of the present invention, the mass percentages of N and Als in the grain-oriented pure iron are: n: 0.005-0.0125%, Als: 0.007-0.035%. N and Al can react to generate AlN, the solid solution temperature of AlN is low, the lower soaking temperature can be adopted in the production process, more inhibitors can be solid-dissolved, the development of primary recrystallization grains is inhibited, the perfection of secondary recrystallization is promoted, and the magnetic induction intensity of grain-oriented pure iron can be further improved. It is worth to say that adding Al to iron can reduce the oxygen and oxide content in steel by deoxidation and increase the magnetic permeability; and Al can coarsen fine AlN, and the nitrogen content is required to be low so as to reduce AlN precipitates, promote the growth of crystal grains during annealing and improve the magnetic permeability; the disadvantage of the increase of Al content in steel is that the magnetic induction intensity under a strong magnetic field is reduced; meanwhile, the Al content has a large influence on the grain size. It is worth further explaining that the mass percentage relationship of N and Als in the grain-oriented pure iron of the invention is as follows: Als/N =2~ 6. When N and Al satisfy the above-described relational expression, a certain amount of AlN can be produced, and the relative contents of N and Al are limited, so that the magnetic induction of grain-oriented pure iron can be increased, and the harm caused by the increase in Al content can be further reduced.
In addition, the mass percentage of Si in the grain-oriented pure iron is Si: 0-0.1%, and a proper amount of silicon can coarsen crystal grains, improve texture, and improve the magnetism and magnetic permeability of the crystal grain oriented pure iron. The mass percentages of Mn and S in the grain-oriented pure iron are respectively as follows: mn: 0-0.1% of Mn, less than 0.005% of S, Mn and S can generate MnS, and the MnS plays a role of an auxiliary inhibitor in the grain-oriented pure iron, so that the magnetic induction intensity of the grain-oriented pure iron can be improved.
It should be noted that the grain-oriented pure iron of the present invention contains, by mass, C: c: 0.02-0.04%, and it is worth saying that the maximum magnetic permeability of the electrical pure iron decreases and the coercive force increases as the carbon content increases. Therefore, the mass percent of C is controlled to be 0.02-0.04%, and the magnetic permeability of the grain-oriented pure iron can be further improved. The chemical components in the grain-oriented pure iron are the balance of inevitable impurities and Fe, excluding the above elements. In conclusion, the grain-oriented pure iron comprises the following chemical components in percentage by mass: c: 0.02 to 0.04%, Si: 0-0.1%, Mn: 0-0.1%, S <0.005%, Als: 0.007-0.035%, N: 0.005-0.0125% of Fe, and the balance of inevitable impurities and Fe. In addition, in the process of increasing the temperature, two extreme points appear in the gamma phase content, wherein the extreme points are 850 ℃ and 1100 ℃, and the gamma phase content is 13-17%, preferably 15%. By controlling the temperature, the generation of the gamma phase can be promoted, the development of secondary recrystallization can be promoted, and the magnetic induction intensity of the grain-oriented pure iron can be further improved.
Referring to fig. 1, the method for producing grain-oriented pure iron includes the following steps:
1) smelting in a converter: the tapping temperature of the converter is 1580-1620 ℃, and 1600 ℃ is preferred. And then refining the converter smelting molten steel by adopting a molten steel vacuum circulation degassing method, and adjusting the components of the molten steel after refining to obtain the refined molten steel, wherein the refining starting temperature is 1580-1600 ℃, and the end temperature is 1540-1560 ℃.
2) Continuous casting: carrying out argon blowing protection casting on the refined molten steel at a long nozzle to obtain a continuous casting slab; wherein the die casting adopts a natural cooling mode. It is worth noting that the slab thickness D1=155 mm.
3) Soaking the raw materials: placing the slab into a soaking furnace for heat preservation treatment, wherein the soaking temperature is 1100-1200 ℃, the soaking time is 160-200 min, and the soaking temperature is preferably 1150 ℃; the soaking time is 180 min. It is worth to say that, when soaking is carried out at 1150 ℃, the inhibitor AlN can be completely dissolved, and Mn and S are also completely dissolved; further, the magnetic induction intensity of the grain-oriented pure iron can be improved.
4) Hot rolling: hot rolling comprises rough rolling and finish rolling; rough rolling pass reduction distribution system: d2= (0.70 to 0.80) D1, D3= (0.75 to 0.85) D2, D4= (0.70 to 0.80) D3, D5= (0.50 to 0.65) D4, D6= (0.50 to 0.60) D5, and D7= (0.45 to 0.60) D6, wherein D2 is the thickness after the first pass rolling, D3 is the thickness after the second pass rolling, D4 is the thickness after the third pass rolling, D5 is the thickness after the fourth pass rolling, D6 is the thickness after the fifth pass rolling, and D7 is the thickness after the sixth pass; the specific numerical value of the rough rolling pass is 155 mm-120 mm-95 mm-70 mm-48 mm-28 mm-15 mm; it is worth noting that when the pressure amount satisfies the above-mentioned relational expression each time, Goss orientation is preferentially formed at a low shearing force during hot rolling, Goss texture appears in the slab, and the magnetic induction of grain-oriented pure iron can be improved. Further, the initial rolling temperature TThick opening1100 to 1120 ℃ and a finishing temperature TRough finishing990-1000 ℃; soaking for 15min after rough rolling at 1100 deg.C; then, finish rolling is carried out, and a distribution system is pressed down in a finish rolling pass: d2' = (0.50-0.60) D7, D3' = (0.60-0.70) D2', D4' = (0.55-0.65) D3 '; d7 is the thickness of the seventh pass of rough rolling, D2 'is the thickness of the first pass of finish rolling, and D3' is the thickness of the second pass of finish rolling and is finish rolling; d4' is the thickness of the third rolling; the specific pressing distribution system in the invention is as follows: 15 mm-8.5 mm-5.5 mm-3.2 mm; by controlling the reduction amount each time, the strength of the GOSS mechanism can be improved, and the magnetic induction intensity of the grain-oriented pure iron can be further improved; in the finish rolling stage, the finish rolling initial temperature is higher than the finish rolling temperature of rough rolling, so that the strength of the GOSS texture can be improved; and the initial rolling temperature TFine opener=（0.88~1）TThick openingPreferably, TFine opener= 1050-1100 ℃, finish rolling temperature TJing Fin (seminal emission)=（0.88~0.91）TRough finishingPreferably, TJing Fin (seminal emission)And = 880-900 ℃. By controlling the rough rolling temperature, inhibitor AlN can be precipitated as little as possible in the rough rolling stage, and by restricting the relation between the finish rolling temperature of finish rolling and the finish rolling temperature of rough rolling, finish rolling can be ensuredAnd the rolling temperature is low, so that the inhibitor is less separated out in the finish rolling stage, the GOSS texture strength can be improved, and the magnetic induction intensity of the grain-oriented pure iron is further improved. In the process of rolling a 155mm slab by hot rolling for 2.3mm, a certain brass texture and a small amount of copper texture are formed in the textures of the surface layer and the subsurface layer of the slab, so that the magnetic induction intensity of the grain-oriented pure iron can be improved. By regulating and controlling the initial and final rolling temperature and the deformation rate, more beneficial texture types can be formed in the plate blank, and the magnetic induction intensity of the grain-oriented pure iron is further improved.
5) Coiling: rapidly coiling after hot rolling, wherein the coiling temperature is 480-500 ℃, and preferably 500 ℃; therefore, the inhibitor which is finely dispersed and distributed can be separated out more quickly, and the magnetic induction intensity of the crystal orientation pure iron can be further improved. Then preserving heat for 1h and cooling along with the furnace.
6) Normalizing: in N2And carrying out two-stage normalizing on the plate blank in a protective atmosphere. Specifically comprises high-temperature section normalizing and low-temperature section normalizing; firstly, normalizing the slab at a high temperature, namely normalizing the temperature T at the high temperatureHeight ofThe temperature is 850-1100 ℃, and the high-temperature section normalizing time is 3-5 min; then, the plate blank is normalized at a low-temperature section, and the temperature T of the normalization at the low-temperature sectionIs low inComprises the following steps: t isIs low in=（0.55~0.95）THeight of. Preferably, the normalizing temperature of the low-temperature section is 600-800 ℃. It is worth to be noted that the normalizing temperature has a significant influence on the size of the crystal grains, and if the normalizing temperature is too high or too long, the inhibitor is coarsened, the inhibiting ability is reduced, and the magnetic performance is further deteriorated; if the normalizing temperature is too low, the normalizing effect is not significant, and the magnetic induction intensity of the grain-oriented pure iron is reduced. Temperature T when the low temperature section is normalizedIs low inAnd a high temperature section normalizing temperature THeight ofWhen the relation is satisfied, more fine AlN particles can be separated from the oriented pure iron, so that the inhibition capability is enhanced, and the development of secondary recrystallization is further facilitated. In addition, the ferrite layer is deepened after the normalization, which is beneficial to slab shape control and Goss texture distribution, thereby being beneficial to the growth of Gaussian grains in the high-temperature annealing process and further improving the magnetic induction intensity of the grain-oriented pure iron. In addition, the temperature setting of the low-temperature stage normalization can be preventedThe water vapor is stopped from flowing back, and the harm caused by sudden temperature drop can be avoided. Further, the time t of the low temperature stage normalizingIs low inLess than or equal to the normalizing time t of the high temperature sectionHeight of(ii) a And the time t of the low temperature section normalizingIs low in=ktHeight ofK is 0.4-1, i.e. tIs low in=（0.4~1）tHeight ofThe normalizing time of the invention has great influence on the performance of the grain-oriented pure iron, and the relationship between the normalizing time of the low-temperature section and the normalizing time of the high-temperature section is limited, so that the grain size can be enlarged, the grains become more uniform, and the magnetic induction intensity of the grain-oriented pure iron can be improved. It is worth to be noted that the value of k and the temperature T of the high temperature section normalizationHeight ofIn positive correlation, i.e. when THeight ofThe larger the value of (A), the larger the value taken by k, THeight ofThe smaller the value of k, the smaller the value of k taken; due to TIs low in=0.55~0.95THeight ofThen through THeight ofControlling the time t of normalizing the low temperature sectionIs low inTherefore, the crystal grains in the high-temperature section normalizing process and the low-temperature section normalizing process become more uniform, the Goss texture can be sharper, and the magnetic induction intensity of the grain-oriented pure iron can be improved. The low-temperature section normalizing time is 2-3 min, and a good effect can be achieved. Cooling the plate blank by boiling water, and finally pickling the plate blank.
7) Cold rolling: carrying out primary cold rolling on the plate blank at normal temperature; specifically, the slab is rolled in three or six passes, so that the thickness of the slab is reduced from 3.2mm to 0.3 mm. It is worth noting that the cold rolling reduction is large, the shearing stress borne by the slab is large at the moment, and further the texture of the slab is changed, so that a strong { 113-115 } <110> texture appears in the slab. Therefore, the grain-oriented pure iron finally forms the cold rolling texture type of {001} <110>, {112} <110>, { 113-115 } <110>, {111} <112>, and the magnetic induction intensity of the grain-oriented pure iron is further improved.
8) Annealing: the annealing comprises decarburization annealing and secondary annealing, wherein the decarburization annealing is carried out on the slab in a nitrogen-hydrogen mixed protective atmosphere, the decarburization annealing temperature is 750-850 ℃, the time is 2-3 min, the dew point is 35-40 ℃, and nitrogen is used as the dew pointAnd the volume percentages of the hydrogen are respectively as follows: n is a radical of2：55~75%，H2: 25-45%. The hydrogen is preferably 25% and the nitrogen is preferably 75%. After decarburization annealing, the grain-oriented pure iron slab exists in {111}<112>Between deformation bands with {110}<001>The oriented subgrains can be preferentially aggregated to form Goss oriented grains, and the low-energy-storage {100} subgrains are not easy to recrystallize due to low energy storage, so that the magnetic permeability of the grain-oriented pure iron is further improved.
Then carrying out secondary annealing on the plate blank, wherein the secondary annealing comprises a temperature rising section, a high-temperature purification section and a temperature reduction section; the protective gas in the temperature rising section is a mixed gas of hydrogen and nitrogen, and the volume ratio of the hydrogen to the nitrogen in the mixed gas is 3: 1; the volume percentage of the hydrogen gas is 75 percent, and N is2The volume percentage is 25%. The temperature rise section comprises a rapid temperature rise stage, a medium-speed temperature rise stage and a slow temperature rise stage; raising the temperature of the plate blank to T in the rapid temperature raising stageTemperature rise，TTemperature rise= 450-550 ℃, and the temperature of the plate blank is controlled from T in the medium-speed heating stageTemperature riseHeating to TMiddle temperature，TMiddle temperature=（1.4~1.5）TTemperature riseIn the slow heating stage, the temperature of the plate blank is changed from TMiddle temperatureHeating to 880-900 ℃. It is worth noting that T in the moderate temperature rise phaseMiddle temperature=（1.4~1.5）TTemperature riseWhen T isMiddle temperatureAnd TTemperature riseWhen the relation is satisfied, the growth of the crystal grains can be promoted, so that the Goss texture is sharper, and the magnetic induction intensity of the crystal grain oriented pure iron can be improved. In addition, the time t of the rapid temperature rise phaseTemperature rise= 0.5-0.6 h, and time t of medium-speed heating-up stageMiddle temperature=（6~8）tTemperature riseThe time of the slow temperature rise stage is tLow temperatureAnd the temperature rise time has a large influence on the secondary recrystallization behavior of the crystal grains, and the time of the medium-speed temperature rise stage is controlled by the time of the quick temperature rise stage, so that the crystal grains have enough time to grow, the inhibitor elements are purified and removed by the time of the quick temperature rise stage, the Goss texture is sharper, and the magnetic induction intensity of the crystal grain oriented pure iron is further improved.
Temperature of high temperature purification sectionTHigh purityIs 880-900 ℃, and is worth pointing out that when the temperature is 900 DEG C<THigh purityWhen the temperature is less than or equal to 910 ℃, the crystal grain oriented pure iron has undergone phase change, and the magnetic performance of the plate blank is greatly deteriorated; within the temperature range of the high-temperature purification section, the temperature T of the high-temperature purification sectionHigh purityThe higher the magnetic induction of the grain-oriented pure iron. Temperature T of the high temperature purification section of the inventionHigh purityIs 900 c so that the best results are achieved. Furthermore, the time of the high-temperature purification section is 9.5-10.5h, and all the gas in the high-temperature purification section is hydrogen, so that enough time is provided for purifying and removing the inhibitor elements. It is worth saying that increasing the annealing time is beneficial to the secondary recrystallization of the grain-oriented pure iron with perfect development, and the Goss texture with concentrated preferred orientation can be rapidly developed under the atmosphere of the total hydrogen in the same high-temperature annealing time, so that the magnetic induction intensity of the grain-oriented pure iron can be improved.
The cooling section comprises a slow cooling stage and a fast cooling stage, wherein the temperature of the plate blank in the slow cooling stage is changed from THigh purityCooling to TTemperature reduction，TTemperature reduction=（0.5~0.6）THigh purityTime t of slow cooling stageTemperature reductionIs 4-4.5H, and the volume ratio of the hydrogen to the nitrogen is H2：N2And the ratio is not less than 3:1, so that the removal of inhibitor elements is promoted, the Goss texture is sharper, and the magnetic induction intensity of grain-oriented pure iron is improved. The temperature of the plate blank is changed from T in the rapid cooling stageTemperature reductionCooling to 40-50 ℃, and the time t of the rapid cooling stageFast fall0.5-0.6 h, gas is 100% N2The rapid cooling can ensure that the grain structure becomes uniform in the cooling process, and the Goss texture can be concentrated.
The grain-oriented pure iron produced by the steps comprises the following chemical components in percentage by mass: c: 0.02 to 0.04%, Si: 0-0.1%, Mn: 0 to 0.1% of S<0.005%, Als: 0.007-0.035%, N: 0.005-0.0125% of Fe, and the balance of inevitable impurities and Fe. And the magnetic induction intensity of the grain-oriented pure iron is B800>1.90T；B10000=2.12~2.15T。
Example 1
In this example, the grain-oriented pure iron comprises the following chemical components in percentage by mass: c =0.04%, Si =0.10%, Mn =0.10%, S =0.005%, Als =0.015%, N =0.007%, and the balance unavoidable impurities and Fe. The specific production steps are as follows:
1) smelting in a converter: the tapping temperature of the converter is 1600 ℃. And then refining the converter smelting molten steel by adopting a molten steel vacuum circulation degassing method, and adjusting the components of the molten steel after refining to obtain refined molten steel. Wherein the starting temperature of refining is 1590 ℃, and the end temperature of refining is 1545 ℃;
2) continuous casting: carrying out argon blowing protection casting on the refined molten steel at a long nozzle to obtain a continuous casting slab; wherein the die casting adopts a natural cooling mode. It is worth noting that the slab thickness is 155 mm.
3) Soaking the raw materials: placing the slab into a soaking furnace for heat preservation treatment, wherein the soaking temperature is 1150 ℃; the soaking time is 180 min.
4) Hot rolling: hot rolling comprises rough rolling and finish rolling; rough rolling pass reduction distribution system: 155 mm-120 mm-95 mm-70 mm-48 mm-28 mm-15 mm; the initial rolling temperature is 1100 ℃, and the final rolling temperature is 1000 ℃; soaking for 15min after rough rolling at 1100 deg.C; then, finish rolling is carried out, and a distribution system is pressed down in a finish rolling pass: 15 mm-8.5 mm-5.5 mm-3.2 mm; the initial rolling temperature is 1100 ℃, and the final rolling temperature is 900 ℃.
5) Coiling: rapidly coiling after hot rolling, wherein the coiling temperature is 500 ℃; then preserving heat for 1h and cooling along with the furnace. .
6) Normalizing: firstly, normalizing the slab at a high temperature section, wherein the normalizing temperature at the high temperature section is 850 ℃ and the time is 3 min; and then, carrying out low-temperature section normalizing on the plate blank, wherein the low-temperature section normalizing temperature is 700 ℃, and the low-temperature section normalizing time is 2 min. And finally, cooling the plate blank by using boiling water and then carrying out acid pickling.
7) Cold rolling: carrying out primary cold rolling on the plate blank at normal temperature; in the embodiment, the thickness of the slab is reduced from 3.2mm to 0.3mm by rolling the slab in three passes.
8) Annealing: first 25% H at a dew point of 45 deg.C2＋75%N2And (3) carrying out decarburization annealing on the slab in the atmosphere, wherein the decarburization annealing temperature is 775 ℃, and the time is 2 min. Then carrying out secondary treatment on the plate blankAnnealing, first at 75% H in this example2＋25% N2Heating under protective atmosphere, and rapidly heating for time tTemperature rise=0.5h，TTemperature rise=500 ℃, and then the temperature of the slab is raised to TMiddle temperature，TMiddle temperature=800 ℃, time t of medium-speed temperature rise stageMiddle temperature=4h, finally raising the temperature of the plate blank to 900 ℃, wherein the time of the slow temperature raising stage is tLow temperature=4h。
Then the high temperature purification section is switched to, the purification is carried out under the pure hydrogen atmosphere, and the temperature T of the high temperature purification sectionHigh purityThe temperature is 900 ℃, and the time of the high-temperature purification section is 10 hours. Then transferring the temperature to a cooling section, wherein the cooling section comprises a slow cooling stage and a fast cooling stage, the slow cooling stage is a nitrogen-hydrogen mixed atmosphere, and H2Volume percent is 75%, N2The volume percentage is 25 percent; the temperature of the plate blank is changed from T in the slow cooling stageHigh purityDown to TTemperature reduction，TTemperature reduction=500 ℃, time t of slow cooling phaseTemperature reductionIs 4 h. Then, the rapid cooling stage is turned into, the atmosphere of the rapid cooling stage is pure hydrogen, and the time t of the rapid cooling stageFast fallThe temperature of the plate blank is controlled from T in the rapid cooling stage to be 0.5hTemperature reductionReduced to 50 deg.c (as shown in figure 2). The obtained grain-oriented pure iron was subjected to magnetic property measurement, and the result was: b is800=1.932T，B10000=2.130T。
Example 2
The present embodiment is basically the same as embodiment 1, except that: in this example, the grain-oriented pure iron comprises the following chemical components in percentage by mass: c =0.02%, Si =0.10%, Mn =0.10%, S =0.005%, Als =0.007%, N =0.007%, and the balance unavoidable impurities and Fe. The production process parameters were the same as in example 1, and the magnetic properties of the obtained grain-oriented pure iron were measured, with the results: b is800=1.942T，B10000=2.126T。
Example 3
The present embodiment is basically the same as embodiment 1, except that: in this example, the chemical composition mass percentage of grain-oriented pure iron was the same as that in example 1, and the process parameters in production were the sameIn this embodiment, the high-temperature section normalizing temperature is 875 ℃, and the time is 3 min; and then, carrying out low-temperature section normalizing on the plate blank, wherein the low-temperature section normalizing temperature is 700 ℃, and the low-temperature section normalizing time is 2 min. The other process parameters were the same as in example 1, and the magnetic properties of the obtained grain-oriented pure iron were measured, and the results were: b is800=1.918T，B10000=2.108T。
Example 4
The present embodiment is basically the same as embodiment 1, except that: in this example, the chemical components of the grain-oriented pure iron were the same in mass percentage as in example 1, and in the production process parameters, purification was performed in a pure hydrogen atmosphere, and the temperature T of the high-temperature section was set toHigh purityThe temperature is 895 ℃, and the time of the high-temperature purification section is 10 h. The remaining production process parameters were the same as in example 1, and the magnetic properties of the obtained grain-oriented pure iron were measured, with the results: b is800=1.945T，B10000=2.124T。
The other process parameters were the same as in example 1, and the magnetic properties of the obtained grain-oriented pure iron were measured, and the results were: b is800=1.959T，B10000=2.139T。
Example 5
The present embodiment is basically the same as embodiment 2, except that: in the embodiment, the chemical components of the grain-oriented pure iron are the same in mass percentage as that in the embodiment 2, and in the production process parameters, the high-temperature section normalizing temperature of the embodiment is 875 ℃, and the time is 3 min; and then, carrying out low-temperature section normalizing on the plate blank, wherein the low-temperature section normalizing temperature is 800 ℃, and the low-temperature section normalizing time is 2 min. The other process parameters were the same as in example 2, and the magnetic properties of the obtained grain-oriented pure iron were measured, and the results were: b is800=1.953T，B10000=2.134T。
From the above examples, it can be seen that the magnetic induction of the grain-oriented pure iron produced by the method of the present invention is B800>1.90T；B10000And = 2.12-2.15T. Namely, the grain-oriented pure iron with higher magnetic induction intensity can be produced by the production method of the grain-oriented pure iron.
The invention has been described in detail hereinabove with reference to specific exemplary embodiments thereof. It will, however, be understood that various modifications and changes may be made without departing from the scope of the invention as defined in the appended claims. The detailed description and drawings are to be regarded as illustrative rather than restrictive, and any such modifications and variations are intended to be included within the scope of the present invention as described herein. Furthermore, the background is intended to be illustrative of the state of the art as developed and the meaning of the present technology and is not intended to limit the scope of the invention or the application and field of application of the invention.

Claims (4)

1. A method for producing grain-oriented pure iron, characterized by: comprises converter smelting, continuous casting, hot rolling, normalizing, cold rolling and annealing; wherein the mass percentages of N and Als in the plate blank obtained after continuous casting are respectively as follows: n: 0.005-0.0125%, Als: 0.007-0.035%; the mass percentage relation of Als and N is as follows: 2-6 of Als/N; the grain-oriented pure iron comprises the following other chemical components in percentage by mass: c: 0.02 to 0.04%, Si: 0-0.1%, Mn: 0-0.1% of S, less than 0.005% of S and the balance of inevitable impurities and Fe, wherein the content of gamma phase is 13-17%; hot rolling comprises rough rolling and finish rolling; the initial rolling temperature of rough rolling is 1100-1120 ℃, and the final rolling temperature is 950-1000 ℃; the initial rolling temperature of finish rolling is 1050-1100 ℃, and the final rolling temperature is 880-900 ℃; normalizing comprises high-temperature section normalizing and low-temperature section normalizing; the temperature of the high-temperature section is 850-1100 ℃, and the temperature of the low-temperature section is 600-800 ℃.
2. The method of producing grain-oriented pure iron according to claim 1, wherein: the cold rolling comprises the following specific steps: and rolling the plate blank to 0.3mm in three or six passes.
3. The method of producing grain-oriented pure iron according to claim 1, wherein: the annealing includes decarburization annealing; the protective gas for decarburization annealing is a mixed gas of nitrogen and hydrogen, and the volume percentages of the nitrogen and the hydrogen in the mixed gas are respectively as follows: n is a radical of2：55～75％，H2：25～45％。
4. A method of producing grain-oriented pure iron according to any one of claims 1 to 3, characterized in that: coiling is also included between the hot rolling and the normalizing, and the coiling temperature is 480-500 ℃.
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