CN101845582B - Production method of high magnetic induction oriented silicon steel - Google Patents
Production method of high magnetic induction oriented silicon steel Download PDFInfo
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- CN101845582B CN101845582B CN2009100482893A CN200910048289A CN101845582B CN 101845582 B CN101845582 B CN 101845582B CN 2009100482893 A CN2009100482893 A CN 2009100482893A CN 200910048289 A CN200910048289 A CN 200910048289A CN 101845582 B CN101845582 B CN 101845582B
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- 229910000976 Electrical steel Inorganic materials 0.000 title claims abstract description 49
- 230000006698 induction Effects 0.000 title claims abstract description 27
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 51
- 238000000137 annealing Methods 0.000 claims abstract description 48
- 239000011248 coating agent Substances 0.000 claims abstract description 34
- 238000000576 coating method Methods 0.000 claims abstract description 34
- 238000010438 heat treatment Methods 0.000 claims abstract description 29
- 238000001816 cooling Methods 0.000 claims abstract description 24
- 238000005098 hot rolling Methods 0.000 claims abstract description 19
- 238000003723 Smelting Methods 0.000 claims abstract description 5
- 238000009749 continuous casting Methods 0.000 claims abstract description 3
- 238000005121 nitriding Methods 0.000 claims description 63
- 238000005261 decarburization Methods 0.000 claims description 29
- 238000005096 rolling process Methods 0.000 claims description 22
- 229910000831 Steel Inorganic materials 0.000 claims description 17
- 239000010959 steel Substances 0.000 claims description 17
- 238000005097 cold rolling Methods 0.000 claims description 16
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 6
- 229910000069 nitrogen hydride Inorganic materials 0.000 claims description 6
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 229910052718 tin Inorganic materials 0.000 claims description 5
- 230000005389 magnetism Effects 0.000 claims description 4
- 230000035515 penetration Effects 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 2
- 229910021529 ammonia Inorganic materials 0.000 claims 1
- 238000010606 normalization Methods 0.000 abstract description 12
- 238000005516 engineering process Methods 0.000 abstract description 6
- 230000001360 synchronised effect Effects 0.000 abstract description 5
- 238000005262 decarbonization Methods 0.000 abstract 3
- 238000009413 insulation Methods 0.000 abstract 1
- 239000000047 product Substances 0.000 description 19
- 239000003112 inhibitor Substances 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 6
- 238000001953 recrystallisation Methods 0.000 description 6
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 230000005764 inhibitory process Effects 0.000 description 4
- 238000005554 pickling Methods 0.000 description 4
- 238000009826 distribution Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000002788 crimping Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 description 1
- 229910052919 magnesium silicate Inorganic materials 0.000 description 1
- 235000019792 magnesium silicate Nutrition 0.000 description 1
- 239000000391 magnesium silicate Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention relates to a production method of high magnetic induction oriented silicon steel, comprising the steps of smelting, continuous casting, hot rolling, normalization, decarbonization and annealing, MgO coating, high-temperature annealing and insulation coating, wherein the normalization comprises the steps that: normalization is carried out on a hot rolling plate, nitridation is finished synchronously, the temperature of normalization and nitridation is 1050-1150 DEG C, the atmosphere is 5-35% NH3 (volume percentage), and the balance of gas is N2; after the normalization and nitridation, the N content nitrided into the hot rolling plate is 60-250ppm; and normalization cooling is carried out, the initial temperature of fast cooling is 700-950 DEG C, and the fast cooling speed with the temperature of being reduced to 550 DEG C is 15-40 DEG C/s. The production method solves the problem of difficult nitridation in the decarbonization procedure when a low-temperature plate blank heating technology is used for producing the high magnetic induction oriented silicon steel, carries out synchronous nitridation on the hot rolling plate in the normalization procedure, and leads the following procedure of decarbonization and annealing techniques to be simplified and easily controlled, thus not only being capable of obtaining a high magnetic induction oriented silicon steel product with excellent performance and simultaneously leading the production cost to be reduced.
Description
Technical Field
The invention relates to a production method of a high magnetic induction oriented silicon steel product, in particular to a low-cost high magnetic induction oriented silicon steel production method, which is characterized in that a hot rolled coil obtained by a low-temperature slab heating (1100-1250 ℃) technology is subjected to synchronous nitriding in a normalizing process, so that a decarburization annealing process of a subsequent process is simplified and is easy to control. The production cost is greatly reduced while the high magnetic induction oriented silicon steel product with excellent magnetic property is obtained.
Background
The production method of the traditional high magnetic induction oriented silicon steel comprises the following steps:
making steel by a converter (or an electric furnace), carrying out secondary refining and alloying, and continuously casting into a plate blank, wherein the basic chemical components of the plate blank comprise Si (2.5-4.5%), C (0.06-0.10%), Mn (0.03-0.1%), S (0.012-0.050%), Als (0.02-0.05%), N (0.003-0.012%), some component systems also comprise one or more of elements such as Cu, Mo, Sb, B, Bi and the like, and the balance is iron and inevitable impurity elements; heating the plate blank in a special high-temperature heating furnace to the temperature of more than 1350 ℃, preserving heat for more than 45min to fully dissolve MnS or AlN favorable for inclusions, then rolling, rapidly spraying water to cool the plate blank to the temperature of less than 500 ℃ when the final rolling temperature reaches more than 950 ℃, and then coiling. So as to separate out fine and dispersed second phase particles, namely inhibitors, in the silicon steel matrix in the subsequent normalizing process; after normalizing the hot rolled plate, carrying out acid cleaning to remove surface iron oxide scales; cold rolling to the thickness of the finished product, decarburizing annealing and coating an annealing separant taking MgO as a main component to remove the [ C ] in the steel plate to the extent of not influencing the magnetism of the finished product (generally below 30 ppm); in the high-temperature annealing process, the steel plate undergoes physical and chemical changes such as secondary recrystallization, formation of a magnesium silicate bottom layer, purification (removal of elements harmful to magnetism such as S, N in the steel) and the like, so that high-magnetic-induction oriented silicon steel with high orientation degree and low iron loss is obtained; finally, the oriented silicon steel product in a commercial application form is obtained through coating an insulating coating and stretching annealing.
The defect of the method is that in order to fully dissolve the inhibitor, the heating temperature needs to reach 1400 ℃ at most, which is the limit level of the traditional heating furnace. In addition, the heating temperature is high, the burning loss is large, the heating furnace needs to be frequently repaired, and the utilization rate is low. Meanwhile, the energy consumption is high, and the edge crack of the hot-rolled coil is large, so that the production of a cold rolling procedure is difficult, the yield is low, and the cost is high.
In view of the problems, research personnel at home and abroad develop a great deal of research on reducing the heating temperature of the oriented silicon steel, and the main improvement trend of the research personnel is divided into two types according to the heating temperature range, wherein the heating temperature of a plate blank is 1250-1320 ℃, and AlN and Cu inhibitors are adopted; the other method is that the heating temperature of the plate blank is 1100-1250 ℃, and the inhibiting capability is obtained mainly by adopting a method of nitriding to form an inhibitor after decarburization.
At present, the low-temperature slab heating technology is developed rapidly, for example, in U.S. Pat. No. US 5049205 and japanese patent No. 5-112827, slab heating is performed at 1200 ℃ or lower, final cold rolling is performed at a large cold rolling reduction of 80%, and after decarburization annealing, continuous nitriding treatment is performed with ammonia gas to obtain secondary recrystallized grains having a high degree of orientation. However, in the method, the inhibition capability is obtained by adopting a method of forming the inhibitor by nitriding after the base plate is decarburized, and the difficulties of serious oxidation, difficult nitriding, non-uniformity and the like of the surface of the strip steel are difficult to overcome in the practical control, so that the obtained inhibitor is difficult to form and non-uniform in distribution in the steel plate, the inhibition capability and the uniformity of secondary recrystallization are influenced, and the magnetic performance of the final product is non-uniform.
Chinese patent CN1978707 describes a new process of nitriding before decarburization annealing for cold-rolled sheet which has been rolled to finished thickness, but requires strict control of dew point during nitriding, and introduces a new problem of difficult decarburization.
Korean patent No. KR2002074312 proposes a method of simultaneous decarburization and nitridation, which can solve the problems of difficult post-decarburization or post-nitridation, but still cannot avoid the problems of non-uniform magnetic properties and high cost of the product due to non-uniform nitridation.
Disclosure of Invention
The invention aims to provide a production method of a high magnetic induction oriented silicon steel product, which solves the problem of difficult nitriding in a decarburization process when the high magnetic induction oriented silicon steel is produced by a low-temperature slab heating technology. By simultaneously nitriding the hot rolled sheet in the normalizing process, the decarburization annealing process in the subsequent process is simplified and easily controlled. This can not only obtain high magnetic induction grain-oriented silicon steel products with excellent magnetic properties, but also reduce the production cost.
The technical scheme of the invention is that,
a production method of high magnetic induction oriented silicon steel comprises smelting, continuous casting, hot rolling, normalizing, cold rolling, decarburization annealing, MgO coating, high-temperature annealing and insulating coating; wherein,
the normalizing comprises hot rolling the plateNormalizing and synchronously completing nitriding, wherein the normalizing nitriding temperature is 1050-1150 ℃, the time is 50-100 s, the dew point is 15-75 ℃, and the atmosphere is 5-35% NH3(volume percent) and the balance of gas N2(ii) a By penetration of the hot-rolled plate after normalizing nitriding]The content is 60-250 ppm;
the content of infiltrated [ N ] and nitriding parameters such as the thickness of the hot rolled plate, nitriding temperature, nitriding time, ammonia gas proportion and the like accord with the following relations:
permeated [ N ]]Content ═ 3.08a2+0.04b+0.96c+4.12d+C
Wherein, a: hot rolled sheet thickness (mm); b: nitriding temperature (. degree. C.); c: nitriding time(s); d: ammonia gas proportion (%); c: a constant;
after normalizing nitriding, controlling a cooling process to realize that the volume fraction of AlN particles with the size less than or equal to 300nm accounts for more than 60 percent of the total volume of AlN; and (3) normalizing and cooling, wherein the initial temperature of rapid cooling is 700-950 ℃, and the rapid cooling speed of cooling to 550 ℃ is 15-40 ℃/sec.
Further, the silicon steel comprises the following chemical components in percentage by weight: c: 0.055 to 0.120%, Si: 2.9-4.0%, Mn: 0.05-0.20%, S: 0.005-0.010%, Als: 0.015-0.035%, N: 0.001 to 0.009%, Sn: 0.005-0.070%, and the balance of Fe and inevitable impurities.
The hot rolling is to heat the plate blank to 1100-1250 ℃ in a heating furnace, keep the temperature for 20-120 minutes, start rolling temperature is 1050-1090 ℃, finish rolling temperature is 930-950 ℃, roll the plate blank into a hot rolled plate with the thickness of 2.0-3.0 mm, perform laminar cooling after rolling, and coil the plate blank at the temperature below 600 ℃.
The cold rolling is to roll the normalized plate to the thickness of a finished plate by using a one-time cold rolling method after normalization.
The decarburization annealing is carried out at a temperature rise rate of 15-35 ℃/sec, a decarburization temperature of 800-860 ℃ and a heat preservation time of 90-160 sec.
The MgO coating and high-temperature annealing: and carrying out MgO coating on the decarburized and annealed steel plate and carrying out high-temperature annealing in a bell-type furnace, wherein the annealing temperature is 1200-1250 ℃.
The insulating coating is as follows: and coating an insulating coating on the surface of the high-temperature annealing plate, and performing hot drawing leveling annealing to obtain the high-magnetic-induction oriented silicon steel with excellent magnetism.
The invention has the advantages of
The normalization of the invention is different from the prior art that the nitriding is completed in the later stage decarburization process, and the nitriding of the hot rolled plate is synchronously completed while the normalization is performed.
The invention increases the content of C, the C can increase the gamma-phase during hot rolling, the structure of the hot rolled plate is refined and is fine deformation crystal grains and small recrystallization crystal grains which are distributed in a layered way, and the primary crystal grains are fine and uniform. In addition, the C height can also improve the hot rolling and cold rolling processability and prevent the hot rolled plate from generating transverse cracks; the smelting operation is easy, the FeO content in the furnace slag is reduced, the steel recovery rate is improved, the service life of the furnace lining is prolonged, and the effect of reducing the production cost is achieved.
The content of S in the steel is reduced, and the formation of MnS is prevented. Further, considering that nitriding is performed while normalizing in the present invention, the content of N in steel can be reduced, thereby improving the quality of a continuously cast slab.
The influence of the content of Als on the magnetic properties is most pronounced. The content of Als is too high, the heating temperature of the plate blank is increased, and the quality of the bottom layer is easy to be deteriorated; the content of Als is too low, and the inhibition effect is weakened.
In the present invention, the steel-making component is added with Sn in an appropriate amount, which can form a Sn-enriched layer on the surface and prevent the nitriding treated steel plate from prematurely denitrifying or absorbing excessive nitrogen during the high-temperature annealing temperature rise. In addition, the steel plate can be completely dissolved in solution during slab reheating, and then the inhibition force is enhanced along grain boundary segregation, so that the primary grain size is finer and more uniform, and the perfect secondary recrystallization is ensured.
According to the invention, nitriding is completed while normalizing the hot rolled plate, so that the normalized plate has the content of N meeting the requirement of low-temperature oriented silicon steel. The N infiltrated into the plate can form partial AlN inhibitor with Als while normalizing, and the inhibitor with ideal size, shape and distribution condition is precipitated under proper normalizing temperature and cooling condition, so that the high-magnetic induction oriented silicon steel product with excellent magnetic performance can be obtained.
According to the invention, nitriding is completed while normalizing the hot rolled plate, so that the normalized plate has the content of N meeting the requirement of low-temperature oriented silicon steel. Therefore, the nitriding process can be omitted during decarburization and annealing of the cold-rolled sheet, and the process requirements are simplified.
Although the hot rolled sheet is thicker than the cold rolled sheet, the time for permeating the same [ N ] content per unit length is about 2 to 3 times longer; however, it is considered that the hot rolled sheet is extended 8 to 10 times in the longitudinal direction after cold rolling. Therefore, the total time taken to nitride the unit weight of the coil in the cold rolled sheet state is much longer than the total time taken to nitride the unit weight of the coil in the hot rolled sheet state. Therefore, nitriding is carried out simultaneously in the normalizing process, so that the production efficiency is greatly improved, and the using amount of ammonia gas can be greatly saved.
Because the hot rolled plate is thicker than the cold rolled plate, more time is needed to ensure that the nitriding amount meets the requirement of the low-temperature oriented silicon steel. However, the prolonged nitriding time can make the distribution of the N content in the normalized hot rolled plate more uniform, and the nitriding uniformity can be completely inherited to the cold rolled plate and the decarburized plate, so that the AlN inhibitor formed in the plate is uniformly dispersed during high-temperature annealing, and the magnetic property of a final product also tends to be more stable.
The proper decarburization temperature can ensure good primary recrystallization of the Gaussian crystal nucleus and lay the foundation for good magnetic performance of the final finished product.
Detailed Description
Example 1
Smelting and casting according to the chemical components shown in the table 1. Placing the plate blanks with different components in a heating furnace with the temperature of 1175 ℃ and keeping the temperature for 90mAnd (3) after in, hot rolling to obtain a hot rolled plate with the thickness of 2.5mm, wherein the initial rolling temperature and the final rolling temperature are 1082 ℃ and 947 ℃ respectively. Normalizing and nitriding the hot rolled plate synchronously, and selecting a proper normalizing and nitriding process: normalizing and nitriding temperature 1115℃ -time 75 s-dew point 40℃ -NH3The ratio of 25% -the cooling starting temperature 820 ℃ and the cooling speed 23 ℃/s-infiltration [ N ]]The content was 172 ppm. Then pickling and cold rolling to the thickness of 0.30 mm. Decarburizing annealing is carried out under the conditions that the temperature rise rate is 26 ℃/s, the decarburizing temperature is 815 ℃ and the temperature uniformity is 150s, so that [ C ] in the steel plate]The content is reduced to below 30 ppm. Coating with a release agent containing MgO as a main component, and then subjecting the resultant coating to a treatment in an atmosphere of 100% H2And the high-temperature annealing is carried out for 20 hours under the conditions that the dew point is-10 ℃ and the temperature is 1200 ℃. After uncoiling, the magnetic properties of the finished product obtained by coating an insulating coating and stretching, flattening and annealing are shown in table 1.
TABLE 1 influence of chemical composition on magnetic Properties
| Examples | C(％) | Si(％) | Mn(％) | S(％) | Als(％) | N(％) | Sn(％) | B8(T) | P17/50(W/kg) |
| 1 | 0.055 | 4.0 | 0.10 | 0.010 | 0.015 | 0.009 | 0.045 | 1.92 | 0.97 |
| 2 | 0.120 | 3.2 | 0.20 | 0.005 | 0.025 | 0.005 | 0.070 | 1.92 | 0.99 |
| 3 | 0.065 | 2.9 | 0.05 | 0.008 | 0.035 | 0.001 | 0.005 | 1.93 | 0.97 |
| 4 | 0.090 | 3.6 | 0.14 | 0.006 | 0.019 | 0.003 | 0.026 | 1.94 | 0.95 |
| 5 | 0.113 | 3.8 | 0.07 | 0.009 | 0.031 | 0.007 | 0.013 | 1.93 | 0.97 |
| 6 | 0.077 | 3.4 | 0.18 | 0.005 | 0.023 | 0.007 | 0.058 | 1.93 | 0.96 |
| Comparative example 1 | 0.052 | 4.2 | 0.15 | 0.006 | 0.013 | 0.010 | 0.035 | 1.87 | 1.08 |
| 2 | 0.070 | 2.7 | 0.04 | 0.004 | 0.037 | 0.008 | 0.072 | 1.87 | 1.11 |
| 3 | 0.124 | 3.5 | 0.22 | 0.011 | 0.029 | 0.0005 | 0.004 | 1.86 | 1.12 |
| 4 | 0.081 | 4.1 | 0.12 | 0.007 | 0.010 | 0.0002 | 0.024 | 1.85 | 1.14 |
Because the invention adopts a 'normalizing-nitriding' synchronous process which is different from the prior art for producing the oriented silicon steel, the optimal chemical composition needs to be determined through experiments.
As can be seen from the results in Table 1, when the chemical components meet the requirements that the magnetic performance of the finished product of the invention is generally good, the magnetic performance of the examples 1-6 is generally good, and the magnetic performance can reach the high magnetic induction grain-oriented silicon steel level (B8 is more than or equal to 1.90T). On the contrary, when the chemical components are not in accordance with the technical scheme of the invention, the magnetic properties of the comparative examples 1-4 are slightly inferior, and can only reach the level of the common oriented silicon steel object (B8 is more than or equal to 1.85T).
Example 2
The oriented silicon steel slab comprises the following components in percentage by weight: 3.25%, C: 0.070%, S: 0.009%, Als: 0.033%, N: 0.05%, Mn: 0.15%, Sn: 0.008% and the balance of Fe and inevitable impurities.
The different hot rolling process conditions are shown in table 2 below. Normalizing and nitriding are synchronously carried out on a 2.3mm hot rolled plate, and a proper normalizing and nitriding process is selected: normalizing nitriding temperature 1085 ℃ to time 65s to dew point 30 ℃ to NH3The proportion is 20 percent, the cooling initial temperature is 780 ℃, the cooling speed is 33 ℃/s, and the permeation is N]The content was 145 ppm. Then pickling and cold rolling to the thickness of 0.30 mm. Decarburizing annealing is carried out under the conditions that the heating rate is 29 ℃/s, the decarburizing temperature is 855 ℃, and the temperature uniformity is 120s, so that [ C ] in the steel plate]The content is reduced to below 30 ppm. Coating with a release agent containing MgO as a main component, and then subjecting the resultant coating to a treatment in an atmosphere of 100% H2And the high-temperature annealing is carried out for 20 hours under the conditions that the dew point is-10 ℃ and the temperature is 1200 ℃. After uncoiling, coatingThe magnetic properties of the finished product obtained by applying the insulating coating and stretching, flattening and annealing are shown in table 2.
TABLE 2 influence of Hot Rolling Process conditions on magnetic Properties
| Serial number | Slab heating system | Initial Rolling temperature (. degree.C.) | Finish Rolling temperature (. degree.C.) | Crimping temperature (. degree.C.) | B8(T) | P17/50(w/kg) |
| Example 1 | 1100℃×120min | 1060 | 945 | 576 | 1.92 | 0.99 |
| 2 | 1250℃×20min | 1070 | 936 | 588 | 1.92 | 1.00 |
| 3 | 1150℃×50min | 1085 | 940 | 564 | 1.93 | 0.96 |
| 4 | 1130℃×100min | 1050 | 950 | 550 | 1.92 | 0.98 |
| 5 | 1210℃×30min | 1065 | 930 | 591 | 1.91 | 0.99 |
| 6 | 1190℃×85min | 1055 | 935 | 600 | 1.93 | 0.96 |
| Comparative example 1 | 1090℃×30min | 1090 | 933 | 577 | 1.86 | 1.11 |
| 2 | 1255℃×50min | 1054 | 954 | 589 | 1.84 | 1.18 |
| 3 | 1140℃×15min | 1072 | 936 | 582 | 1.84 | 1.16 |
| 4 | 1160℃×130min | 1081 | 941 | 580 | 1.86 | 1.12 |
| 5 | 1135℃×45min | 1041 | 941 | 584 | 1.87 | 1.10 |
| 6 | 1125℃×65min | 1098 | 932 | 590 | 1.87 | 1.09 |
| 7 | 1215℃×55min | 1052 | 923 | 592 | 1.88 | 1.06 |
| 8 | 1170℃×80min | 1086 | 957 | 568 | 1.86 | 1.11 |
| 9 | 1195℃×60min | 1066 | 939 | 616 | 1.86 | 1.09 |
Because the technical scheme of the invention adopts a 'normalizing-nitriding' synchronous process which is different from the prior production of oriented silicon steel, the optimal hot rolling process scheme needs to be determined through tests. From the results in Table 2, it can be seen that when the hot rolling process satisfies the technical scheme of the invention, namely the slab is heated to 1100-1250 ℃ in the heating furnace, the heat preservation time is 20-120 minutes, the initial rolling temperature is 1050-1090 ℃, the final rolling temperature is 930-950 ℃, the slab is rolled into a hot rolled plate with the thickness of 2.0-3.0 mm, the hot rolled plate is cooled by laminar flow after rolling, and the coiled plate is coiled at the temperature of below 600 ℃, the magnetic performance of the examples 1-6 is generally good, and the high magnetic induction oriented silicon steel object level (B8 is more than or equal to 1.90T) can be achieved. On the contrary, when the hot rolling process is inconsistent with the technical scheme of the invention, the magnetic performance of the comparative examples 1-9 is slightly poorer, and can only reach the level of the common oriented silicon steel object (B8 is more than or equal to 1.85T).
Example 3
The oriented silicon steel slab comprises the following components in percentage by weight: 3.25%, C: 0.070%, S: 0.009%, Als: 0.033%, N: 0.05%, Mn: 0.15%, Sn: 0.008% and the balance of Fe and inevitable impurities. Keeping the temperature of the hot rolled plate in a heating furnace at 1190 ℃ for 30min, and then hot rolling the hot rolled plate to a hot rolled plate with the thickness of 2.3mm, wherein the initial rolling temperature and the final rolling temperature are 1080 ℃ and 942 ℃ respectively. The different normalization and nitridation process conditions are shown in table 3 below. Then pickling and cold rolling to the thickness of 0.30 mm. Decarburizing and annealing are carried out under the conditions that the heating rate is 28 ℃/s, the decarburizing temperature is 855 ℃ and the temperature is 140s so as to lead the [ C ] in the steel plate to]The content is reduced to below 30 ppm. Coating with a release agent containing MgO as a main component, and then subjecting the resultant coating to a treatment in an atmosphere of 100% H2And the high-temperature annealing is carried out for 20 hours under the conditions that the dew point is-10 ℃ and the temperature is 1200 ℃. After uncoiling, the finished product magnetic property and AlN volume fraction are shown in Table 3 after coating an insulating coating and stretching, flattening and annealing.
As the prior art for producing the oriented silicon steel does not have a process for synchronously performing normalization-nitridation. Therefore, the present invention requires the determination of the optimal process recipe by the "normalization-nitridation" test of table 3. From the test results in Table 3, it can be seen that when the "normalizing-nitriding" process satisfies the technical scheme of the invention, normalizing and nitriding are completed at the same time, the normalizing and nitriding temperature is 1050-1150 ℃, the time is 50-100 s, the dew point is 15-75 ℃, and the atmosphere is 5-35% NH3(volume percent) and the balance of gas N2(ii) a By penetration of the hot-rolled plate after normalizing nitriding]The content is 60-250 ppm. The normalizing cooling starting temperature is 700-950 ℃, and when the temperature is reduced to 550 ℃ and the rapid cooling speed is 15-40 ℃/sec, the magnetic performance of the embodiment (1# -10 #) is generally good, and the high magnetic induction grain-oriented silicon steel object level (B8 is more than or equal to 1.90T) can be achieved. On the contrary, when the normalizing-nitriding process is not consistent with the technical scheme of the invention, the magnetic performance of the comparative examples (11# to 25#) is slightly poorer, and can only reach the level of common oriented silicon steel objects (B8 is more than or equal to 1.85T).
[ N ] listed in Table 4]The contents are all values actually measured after the hot rolled sheet is subjected to the frequent nitriding. The nitriding parameters in Table 3 are now used with "infiltrated [ N]Content ═ 3.08a2And the theoretical nitriding value is calculated by a formula of +0.04b +0.96C +4.12d + C, and the constant C is 23.51. Table 4 is the difference between the two.
TABLE 4 difference between theoretical calculated value and actual value of N content formula
| Normalizing nitriding temperature (. degree. C.) | Normalizing nitriding time (sec) | Normalizing nitriding atmosphere (NH)3％) | Actual penetration [ N]Content (ppm) | Theoretical calculation of [ N ]]Content (ppm) | Difference (ppm) |
| 1050 | 50 | 25 | 158 | 153.2 | -4.8 |
| 1060 | 100 | 15 | 157 | 160.4 | 3.4 |
| 1075 | 55 | 20 | 134 | 138.4 | 4.4 |
| 1095 | 75 | 35 | 224 | 220.2 | -3.8 |
| 1100 | 60 | 30 | 186 | 185.4 | -0.6 |
| 1110 | 65 | 5 | 81 | 87.6 | 6.6 |
| 1120 | 55 | 10 | 103 | 99.0 | -4.0 |
| 1125 | 95 | 20 | 172 | 178.8 | 6.8 |
| 1135 | 50 | 30 | 180 | 177.2 | -2.8 |
| 1150 | 80 | 5 | 97 | 103.6 | 6.6 |
| 1120 | 65 | 15 | 131 | 129.2 | -1.8 |
| 1040 | 75 | 25 | 175 | 176.8 | 1.8 |
| 1155 | 55 | 10 | 93 | 100.4 | 7.4 |
| 1135 | 45 | 20 | 135 | 131.2 | -3.8 |
| 1085 | 105 | 5 | 125 | 125.0 | 0 |
| 1100 | 60 | 30 | 185 | 185.4 | 0.4 |
| 1090 | 70 | 10 | 115 | 112.2 | -2.8 |
| 1060 | 80 | 3 | 95 | 91.8 | -3.2 |
| 1115 | 50 | 40 | 213 | 217.6 | 4.6 |
| 1075 | 75 | 35 | 216 | 219.4 | 3.4 |
| 1150 | 65 | 25 | 170 | 171.6 | 1.6 |
| 1050 | 60 | 15 | 124 | 121.6 | -2.4 |
| 1095 | 85 | 5 | 110 | 106.2 | -3.8 |
| 1050 | 50 | 5 | 58 | 70.8 | 12.8 |
| 1150 | 100 | 35 | 253 | 246.4 | -6.6 |
From the results of Table 4, it can be found that the difference between the actual value of nitriding and the theoretical value calculated is substantially within 10 ppm. Therefore, the formula has good guiding significance for the normalized nitriding of the hot rolled plate.
Example 4
The oriented silicon steel slab comprises the following components in percentage by weight: 3.25%, C: 0.070%, S: 0.009%, Als: 0.033%, N: 0.05%, Mn: 0.15%, Sn: 0.008% and the balance of Fe and inevitable impurities. Keeping the temperature of the hot rolled plate in a heating furnace at 1190 ℃ for 30min, and then hot rolling the hot rolled plate to a hot rolled plate with the thickness of 2.3mm, wherein the initial rolling temperature and the final rolling temperature are 1080 ℃ and 942 ℃ respectively. Normalizing and nitriding the hot rolled plate synchronously, and selecting a proper normalizing and nitriding process: normalizing and nitriding temperature 1125-time 65 s-dew point 60-NH3The proportion is 20 percent, the cooling initial temperature is 850 ℃, the cooling speed is 20 ℃/s, and the N is permeated]The content was 147 ppm. Then pickling and cold rolling to the thickness of 0.30 mm. The different decarburization annealing process conditions are shown in table 5 below. After decarburization annealing, [ C ] is allowed to stand in the steel sheet]The content is reduced to below 30 ppm. Coating with a release agent containing MgO as a main component, and then subjecting the resultant coating to a treatment in an atmosphere of 100% H2And the high-temperature annealing is carried out for 20 hours under the conditions that the dew point is-10 ℃ and the temperature is 1200 ℃. After uncoiling, the magnetic properties of the finished product obtained by coating an insulating coating and stretching, flattening and annealing are shown in table 5.
TABLE 5 Effect of different decarburization annealing processes on the magnetic properties of the finished product
Because the technical scheme of the invention adopts a brand-new 'normalizing-nitriding' synchronous process, the optimal decarburization annealing process scheme needs to be determined through tests. As can be seen from Table 5, when the decarburization annealing process satisfies the technical scheme of the invention, namely the decarburization temperature rise speed is 15-35 ℃/sec, the decarburization temperature is 800-860 ℃, and the decarburization annealing time is 90-160 sec, the magnetic performance of the examples 1-6 is generally good, and the high magnetic induction grain-oriented silicon steel material level (B8 is more than or equal to 1.90T) can be achieved. On the contrary, when the decarburization annealing process is inconsistent with the technical scheme of the invention, the magnetic performance of the comparative examples 7-12 is slightly poorer, and can only reach the level of the common oriented silicon steel object (B8 is more than or equal to 1.85T).
The high magnetic induction grain-oriented silicon steel produced by the low-temperature slab heating technology has the advantages of long service life of a heating furnace, low energy consumption and cost and the like. However, since the post-process decarburization and nitridation are not uniform and effective adjustment and control are difficult in the production process, the suppression capability of local or whole substrate is affected, secondary recrystallization is not perfect, and the magnetic performance of the product is not stable.
The invention relates to a novel high magnetic induction grain-oriented silicon steel production method based on a low-temperature slab heating technology, which effectively solves the problems. The method is characterized in that the normalization and the nitriding are synchronously completed on the hot rolled plate, so that the decarburization process can be successfully simplified under the component system of the current low-temperature oriented silicon steel, and the production efficiency is improved. In addition, compared with other methods, the method of the invention has great advantages in improving the magnetic performance and stability of the finished product.
Claims (7)
1. A production method of high magnetic induction oriented silicon steel comprises smelting, continuous casting, hot rolling, normalizing, cold rolling, decarburization annealing, MgO coating, high temperature annealing and insulating coating, and is characterized in that,
normalizing comprises normalizing the hot rolled plate and synchronously completing nitriding, wherein the normalizing nitriding temperature is 1050-1150 ℃, the time is 50-100 s, the dew point is 15-75 ℃, and the atmosphere is 5-35% NH3(volume percent) and the balance of gas N2(ii) a By penetration of the hot-rolled plate after normalizing nitriding]The content is 60-250 ppm;
the content of permeated [ N ] corresponds to the following relationship with the thickness of the hot rolled sheet, nitriding temperature, nitriding time and ammonia gas ratio:
permeated [ N ]]Content ═ 3.08a2+0.04b+0.96c+4.12d+C
Wherein, a: thickness of hot rolled sheet, unit: mm; b: nitriding temperature, unit: DEG C; c: nitriding time, unit: s; d: ammonia ratio, unit: percent; c: a constant;
after normalizing nitriding, controlling a cooling process to realize that the volume fraction of AlN particles with the size less than or equal to 300nm accounts for more than 60 percent of the total volume of AlN; and (3) normalizing and cooling, wherein the initial temperature of rapid cooling is 700-950 ℃, and the rapid cooling speed of cooling to 550 ℃ is 15-40 ℃/sec.
2. The method for producing the high magnetic induction oriented silicon steel as claimed in claim 1, wherein the silicon steel comprises the following chemical components in percentage by weight: c: 0.055 to 0.120%, Si: 2.9-4.0%, Mn: 0.05-0.20%, S: 0.005-0.010%, Als: 0.015-0.035%, N: 0.001 to 0.009%, Sn: 0.005-0.070%, and the balance of Fe and inevitable impurities.
3. The method for producing high magnetic induction oriented silicon steel according to claim 1, wherein the hot rolling is carried out by heating a slab in a heating furnace to 1100 to 1250 ℃, holding the temperature for 20 to 120 minutes, rolling the slab at 1050 to 1090 ℃ at the initial rolling temperature and 930 to 950 ℃ at the final rolling temperature, rolling the slab into a hot rolled plate with a thickness of 2.0 to 3.0mm, carrying out laminar cooling after rolling, and coiling the slab at a temperature of 600 ℃ or lower.
4. The method for producing high magnetic induction oriented silicon steel according to claim 1, wherein the cold rolling is performed by rolling the normalized sheet to a thickness of a finished sheet by a single cold rolling method after normalizing.
5. The method for producing a high magnetic induction oriented silicon steel as claimed in claim 1, wherein said decarburization annealing is carried out at a temperature rise rate of 15 to 35 ℃/sec, a decarburization temperature of 800 to 860 ℃, and a temperature hold of 90 to 160 sec.
6. The method for producing high magnetic induction oriented silicon steel according to claim 1, characterized in that said MgO coating and high temperature annealing: and carrying out MgO coating on the decarburized and annealed steel plate and carrying out high-temperature annealing in a bell-type furnace, wherein the annealing temperature is 1200-1250 ℃.
7. The method of producing high magnetic induction oriented silicon steel according to claim 1, wherein the insulating coating is: and coating an insulating coating on the surface of the high-temperature annealing plate, and performing hot drawing leveling annealing to obtain the high-magnetic-induction oriented silicon steel with excellent magnetism.
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| CN102443736B (en) * | 2010-09-30 | 2013-09-04 | 宝山钢铁股份有限公司 | Method for producing high magnetic flux-density oriented silicon steel product |
| CN102560236B (en) * | 2010-12-17 | 2013-07-31 | 鞍钢股份有限公司 | Preparation method of common oriented silicon steel |
| CN102758127B (en) * | 2011-04-28 | 2014-10-01 | 宝山钢铁股份有限公司 | Method for producing high magnetic induction orientation silicon steel with excellent magnetic performance and good bottom layer |
| CN103695619B (en) | 2012-09-27 | 2016-02-24 | 宝山钢铁股份有限公司 | A kind of manufacture method of high magnetic strength common orientation silicon steel |
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| CN103484643B (en) * | 2013-08-23 | 2015-04-15 | 安阳钢铁股份有限公司 | Method for preventing hot rolling edge fractures in oriented silicon steel |
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| CN106435134B (en) * | 2016-11-02 | 2018-07-06 | 浙江华赢特钢科技有限公司 | A kind of production technology of silicon steel sheet |
| CN106755874B (en) * | 2016-11-18 | 2018-06-26 | 武汉钢铁有限公司 | A kind of decarburization for producing low temperature high magnetic induction grain-oriented silicon steel and nitriding method for annealing |
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| CN112626447A (en) * | 2020-12-14 | 2021-04-09 | 海安华诚新材料有限公司 | Atmosphere control process of high-magnetic-induction oriented silicon steel with excellent magnetism |
| CN116024420B (en) * | 2023-03-23 | 2023-07-28 | 首钢智新迁安电磁材料有限公司 | High-magnetic-induction oriented silicon steel and preparation method thereof |
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