CN101748259A

CN101748259A - Method for producing high magnetic induction grain-oriented silicon steel by low temperature heating

Info

Publication number: CN101748259A
Application number: CN200810229771A
Authority: CN
Inventors: 蒋奇武; 金文旭; 庞树芳; 游青雷; 付勇军; 张静; 张海利
Original assignee: Angang Steel Co Ltd
Current assignee: Angang Steel Co Ltd
Priority date: 2008-12-12
Filing date: 2008-12-12
Publication date: 2010-06-23
Anticipated expiration: 2028-12-12
Also published as: CN101748259B

Abstract

The invention discloses a method for producing high magnetic induction grain-oriented silicon steel by low temperature heating, which comprises the following steps: heating a grain-oriented silicon steel plate blank produced by a common process; performing hot rolling; annealing or normalizing the hot-rolled plate, performing one-pass cold rolling with heavy reduction rate, and rolling the plate into the thickness approximate to that of a finished product; decarburizing in wet atmosphere; nitriding and coating a parting agent; and finally performing high temperature annealing. The method is characterized in that: the heating temperature for the plate blank is controlled to below 1,280 DEG C; before the nitriding, the decarburized plate is subjected to 1.5 to 3 percent critical deformation cold rolling to damage a SiO2 film under the condition of no lubrication; and the parting agent is Al2O3 fine particles with the size less than 10 mu m, and 5 to 30 weight percent of TiO2 is added into the Al2O3 fine particles. The method solves the problem that the SiO2 film is formed on the surface of the decarburized plate to barrier the nitriding; and a glass film underlayer with good performance is obtained simultaneously.

Description

A kind of method of producing high magnetic induction grain-oriented silicon steel by low temperature heating

Technical field

The present invention relates to a kind of production method of high magnetic induction grain-oriented silicon steel, especially a kind of method of producing high magnetic induction grain-oriented silicon steel by low temperature heating.

Background technology

At present, the orientation silicon steel production technology flow process is generally: blast furnace ironmaking → converter smelting → external refining → continuous casting+induction stirring → strand spraying oxygen-proof film → heating and hot rolling → normalizing (Hi-B) → cold rolling → process annealing (GO) → secondary cold-rolling (GO) → decarburizing annealing and coating MgO separant → finished product high temperature annealing → hot-leveling stretch and anneal and coating coating insulating film → rewinding packing.

In industrial scale, the control techniques of inhibitor can be divided into two classes.A kind of is common technology, and promptly slab is heated to more than the solid solubility temperature of inhibitor (as AlN and MnS),, is called " method of inherent inhibitor " (＞1300 ℃) so that their disperses are separated out; Another kind of by company of Nippon Steel " obtain inhibitor method " (1100～1200 ℃) that grow up, be that slab heating temperature is enough low, the necessary inhibitor of secondary recrystallization is to finish in decarburizing annealing to form before beginning to final finished annealed secondary recrystallization, its means are exactly nitriding in steel, make it to combine with original element in the steel, be formed with (Al, Si) the N precipitate of inhibitor function.

Making when being the Hi-B oriented silicon steel of intrinsic inhibitor with AlN+MnS, the Heating temperature of strand＞1300 ℃, and adopt the once cold rolling draft rolling greater than 85% heavy reduction rate, more most important is to guarantee to separate out from making steel the normalizing process AlN disperse.

In course of hot rolling, finishing temperature must be more than 1100 ℃, because silicon steel must be from the zone fast cooling of γ-phase volume fraction greater than set-point; Because requiring to have volume fraction is γ-phase of 40%～50%, Si content is 3.25% o'clock, and the C content of requirement is 0.07%～0.08%.These characteristics have caused the following difficulty of developing new product.

The heat difficulty

Heat makes iron scale many, and lumber recovery is low; Repair stove rate height, output reduces; Fuel consumption is many; Furnace campaign is short; The manufacturing cost height; Surface defects of products increases.

(1) increases Si content difficulty

If will reduce iron loss by increasing silicone content, also must increase C content, yet, increasing the decarburization difficulty that C content makes silicon steel, the result can cause the hysteresis of finished product.

(2) produce thin specification silicon steel product difficulty

With cold rolling draft approximately is 87% to produce thin slab product, needs to reduce hot rolled coil thickness specification.Yet, can not keep high finishing temperature again to the hot rolled coil that is lower than specific grade.

For fear of with the metallurgy problem of AlN as intrinsic inhibitor manufacturing Hi-B oriented silicon steel, also in order to make product innovation, the normal now acquisition inhibitor method that adopts the slab low-temperature heat.The manufacturing processed of intrinsic inhibitor and acquisition inhibitor method is basic identical, makes the Hi-B product by the method for once cold rolling.The essential distinction of two kinds of methods is as shown in table 1, and the method that obtains inhibitor is inhibitor with AlN, adopts the heating of low temperature slab, will carry out nitriding after the decarburizing annealing.

The characteristics of two kinds of manufacture method of table 1

Mn forms MnO and can be used as MgO and SiO after decarburizing annealing ₂The catalyst of reaction has improved the glassy membrane quality.MnS has played effective function when forming glassy membrane.With AlN is main inhibitor, does not re-use MnS when adopting the method for above-mentioned acquisition inhibitor to produce oriented silicon steel, and the decarburizing annealing rear surface forms the thick SiO of 10～20nm ₂Film is a very big obstacle to nitriding.

Summary of the invention

The object of the present invention is to provide a kind of method of producing high magnetic induction grain-oriented silicon steel by low temperature heating, solve the SiO that decarburizing annealing plate surface forms ₂Film hinders the problem of nitriding, simultaneously the good glassy membrane bottom of obtained performance.

For achieving the above object, the main technical schemes taked of the present invention is as follows:

(1) will then carry out hot rolling with the directional silicon steel slab of common explained hereafter in heating below 1280 ℃, hot-rolled sheet annealing or normalizing are rolled down near finished product thickness after a heavy reduction rate is cold rolling, carry out decarburizing annealing again in wet atmosphere;

(2) the decarburizing annealing plate carries out 1.5%～3% the cold rolling SiO that destroys of critical strain under not lubricated situation ₂Film then carries out nitriding and handles, and nitriding temperature is 830～870 ℃; Nitriding time is 5～50 seconds; Nitriding medium is NH ₃

(3) on the surface of steel plate after the nitriding, be coated with the fine particle Al of size＜10um with electrostatic method ₂O ₃, wherein adding weight percent is 5%～30%TiO ₂

(4) finally manufacture the Hi-B oriented silicon steel of excellent property through high temperature annealing, the smooth annealing of thermal stretch and coating insulating coating.

When adopting the production of acquisition inhibitor method to be the low temperature Hi-B oriented silicon steel of inhibitor, must handle the inhibition ability of strengthening AlN by nitriding after the decarburizing annealing with AlN, but the fine and close SiO that in the decarburizing annealing process, forms ₂Film can make the control breakdown of nitriding ability.Under not lubricated situation, cold rolling through 1.5%～3% critical strain, broken SiO ₂Oxide film carries out so that nitriding process is easier.

MgO and SiO ₂Reaction forms magnesium silicate glass film bottom in high-temperature annealing process, now because the cold rolling SiO that destroyed of critical strain ₂Film, the glassy membrane degradation of formation.Because Al ₂O ₃Not with SiO ₂React, with the fine particle Al of size＜10um ₂O ₃As the main separant of high temperature annealing, do not form glassy membrane behind the high temperature annealing, surperficial metal luster, the punching performance obviously improves, P _1.7Also reduce.

The present invention compared with prior art has following beneficial effect:

1) the decarburizing annealing plate is cold rolling through 1.5%～3% critical strain under not lubricated situation, can effectively destroy the SiO that forms after the decarburizing annealing ₂Surface film oxide improves nitriding efficient;

2) You Yi Al ₂O ₃Coating does not form the glassy membrane bottom, and the top layer is even, obtains good magnetic performance;

3) guaranteed the enforcement of smooth annealing of subsequent thermal and insulating coating.

Embodiment

The present invention is further described by the following embodiment.

1, technology general requirement

(1) technical process:

Blast furnace ironmaking → converter smelting → external refining → continuous casting → heating and hot rolling → heavy reduction rate once cold rolling → decarburizing annealing → critical strain is cold rolling → and nitriding handles → is coated with Al ₂O ₃Separant → finished product high temperature annealing → hot-leveling stretches and anneals and coating coating insulating film → rewinding packing

(2) molten steel chemical ingredients (weight percent): 0.02%～0.09%C, 2.8%～3.8%Si, 0.01%～0.2%Mn ,≤0.035%P, 0.001%～0.02%S ,≤0.01%N ,≤0.03%Als, all the other are iron and a small amount of inclusion;

(3) strand is gone into furnace temp 〉=300 ℃, and best 〉=900 ℃ are at 1200 ℃～1280 ℃ scope insulation＜3h, then carry out hot rolling, hot-rolled sheet annealing or normalizing are rolled down near finished product thickness after a heavy reduction rate is cold rolling, carry out decarburizing annealing again in wet atmosphere;

(4) before the nitridation process, the decarburizing annealing plate is earlier cold rolling through 1.5%～3% critical strain under lubrication circumstances not, again under 830～870 ℃ temperature, and decomposing N H ₃Carrying out the nitriding of 5～50s in the atmosphere handles;

(5) on the surface of steel plate after the nitriding, be coated with the fine particle Al of size＜10um with electrostatic method ₂O ₃, wherein adding weight percent is 5%～30%TiO ₂

(6) finally manufacture the Hi-B oriented silicon steel of excellent property through high temperature annealing, the smooth annealing of thermal stretch and coating insulating coating.

2, specific embodiment

Get composition strand as shown in table 2, average mark was slit into 6 after crop truncated, and tested according to above-mentioned technology respectively.The processing parameter and the magnetic property detected result of test see Table 3.

The table 2 experiment chemical ingredients (wt%) of steel

??C	??Si	??Mn	??P	??S	??Als	??N
??C	??Si	??Mn	??P	??S	??Als	??N	??0.055	??3.3	??0.20	??0.033	??≤0.005	??0.03	??0.008

Claims

1. the method for a producing high magnetic induction grain-oriented silicon steel by low temperature heating, to heat with the directional silicon steel slab of common explained hereafter, then carry out hot rolling, hot-rolled sheet annealing or normalizing are rolled down near finished product thickness after a heavy reduction rate is cold rolling, carry out decarburizing annealing again in wet atmosphere, carry out nitriding afterwards, the coating separant carries out high temperature annealing at last, and it is characterized in that: slab heating temperature is controlled at below 1280 ℃; The decarburizing annealing plate carries out 1.5%～3% the cold rolling SiO that destroys of critical strain before the nitriding under not lubricated situation ₂Film; Described separant is Al ₂O ₃Fine particle, wherein adding weight percent is 5%～30%TiO ₂

2. the method for producing high magnetic induction grain-oriented silicon steel by low temperature heating according to claim 1, it is characterized in that: slab is gone into furnace temp and is 〉=300 ℃, and heating and temperature control is at 1200 ℃～1280 ℃ scopes, insulation＜3h.

3. the method for producing high magnetic induction grain-oriented silicon steel by low temperature heating according to claim 1, it is characterized in that: the nitriding temperature of decarburizing annealing plate is 830～870 ℃, and nitriding time is 5～50 seconds, and nitriding medium is NH ₃

4. the method for producing high magnetic induction grain-oriented silicon steel by low temperature heating according to claim 1 is characterized in that: separant Al ₂O ₃Fine particle size＜10um, and apply with electrostatic method.