JPS5850298B2 - Processing method for electrical steel sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stably manufacturing an electrical steel sheet having excellent magnetic properties and insulation properties.

Examples of electromagnetic steel sheets include non-oriented electromagnetic steel sheets used in rotating machines such as motors, and grain-oriented electromagnetic steel sheets used in transformers and the like.

Non-oriented electrical steel sheets are pure iron-based or silicon steel sheets containing 3.5% or less silicon, and after pickling hot coils,
It is manufactured by repeating cold rolling and annealing one or two times to make the axis of easy magnetization random with respect to the rolling direction, and then applying an insulation coating treatment.

On the other hand, grain-oriented electrical steel sheets are generally manufactured as follows.

That is, it contains 2.5-4.0% silicon and contains AlN, MnS, BN, Se as inhibitors.
.

A hot coil containing a predetermined amount of one or more of the elements forming CuS, Sb, etc. is pickled, cold rolled and annealed once or twice, and then subjected to secondary recrystallization (110).
In order to selectively grow crystals with (001) orientation, final annealing is performed at 100'O to 1200°C.

In the case of a batch type in which final annealing is performed for each coil, refractory oxides such as magnesia, silica, alumina, titanium oxide, calcium oxide, etc. are used as annealing separators to prevent seizure.

In this case, using an annealing separator containing magnesia as a main component will prevent seizure and at the same time prevent Si from forming on the surface of the steel sheet during annealing.
O2 and magnesia react to form a glass film whose main component is 2Mg0.5in2 (forsterite).

This glass coating is not only effective as a base for an insulating coating, but also improves core loss and reduces magnetostriction by applying tension to the steel sheet, and is generally used in the production of grain-oriented electrical steel sheets with such a glass coating. is the mainstream.

In this way, after secondary recrystallization is caused by finish annealing and a glass film is formed on the electrical steel sheet, the excess magnesia is removed, and then, as shown in Japanese Patent Publication No. 27-1268, for example, magnesium phosphate-based Processing liquid and
As shown in Publication No. 28375, a colloidal silica-aluminum phosphate-chromic acid treatment solution is applied, and the film is baked at 700 to 900°C, simultaneously removing curls and flattening the steel plate. training is being carried out.

In this case, if a treatment solution containing colloidal silica, such as that shown in the latter Japanese Patent Publication No. 53-28375, is treated at the temperature mentioned above, the film becomes glassy and tension is applied to the steel plate during cooling, causing iron loss. This is advantageous because the effect of improving properties such as magnetostriction is large.

However, in order to increase the tension effect, the amount of application should be increased from 4 to 4.
Because it is necessary to apply a large amount of 7 g/m”,
Although the insulation properties are excellent, the space factor is poor, and there are problems with workability, such as peeling of the edges during processing such as slitting and cutting.

The present invention aims to provide a processing method for obtaining an electrical steel sheet with excellent magnetism (iron loss, magnetostriction), insulation properties, space factor, and workability without having the drawbacks of the above-mentioned conventional proposals. This is the purpose.

The purpose of the present invention is basically to irradiate the surface of a finish-hardened electrical steel sheet with a laser beam to form laser marks locally on the surface of the steel sheet, and then insulate the surface of the steel sheet. This is achieved by a combination of carrying out the coating treatment and carrying out the coating treatment in a low temperature range where the laser beam irradiation treatment effect imparted to the steel sheet does not disappear.

More specifically, according to the study results of the present inventors, the best results can be obtained by carrying out the laser beam irradiation treatment to such an extent that laser marks are produced on the surface of the steel plate.

It is desirable that these laser marks do not exist from the viewpoint of insulation and voltage resistance, but according to the study of the present inventors, if an insulating film of a predetermined thickness is applied after laser beam irradiation treatment, the insulation and voltage resistance caused by laser marks can be improved. Iron loss can be improved without reducing voltage properties.

By the way, as mentioned above, the insulation coating treatment is usually performed at the same time as the flattening treatment and the baking treatment at a board temperature of 700° C. to 900° C.

On the other hand, according to the experimental results of the present inventors, it was found that when the temperature of the steel plate exceeds 600° C. after laser beam irradiation treatment, the effect disappears.

Based on these findings, in the present invention, the insulation film treatment performed after the laser beam irradiation treatment is performed in a low temperature range where the laser beam irradiation treatment effect does not disappear, specifically, at a plate temperature of 6.
Baking is a process performed at temperatures below 00°C.

It is also possible to carry out the laser beam irradiation treatment after the insulation coating treatment, but in this case, the coating evaporates due to the laser beam irradiation, exposing the base metal surface, resulting in a severe drop in insulation properties and voltage resistance.

Also from this point of view, the laser beam irradiation treatment is performed before the insulation coating treatment.

The application of a laser beam to the surface of an electromagnetic steel sheet is described in Japanese Patent Publication No. 54-23647.

However, the method described in Japanese Patent Publication No. 54-23647 is applied to a steel plate to prevent the growth of secondary recrystallized grains before the final high-temperature annealing process, and the method described in Japanese Patent Publication No. 54-23647 prevents the growth of secondary recrystallized grains. An invention is a purpose, structure,
They are completely different in terms of action and effect.

FIG. 1 shows the relationship between insulation coating treatment temperature and magnetism (iron loss) when a high magnetic flux density unidirectional electrical steel sheet is subjected to laser beam irradiation treatment and then insulation coating treatment.

In this case, the surface of the unidirectional electrical steel sheet has a glass film, and (1) Flattening treatment conditions: 870°C x 70S
eC, in N2, (2) pulsed laser beam energy density 15 J/cwt, single-sided C direction point irradiation,
The diameter of the dotted traces is 0.1 rnN, the center spacing in the dotted trace row C direction is 0.5, and the spacing in the dotted trace row direction is 10 rItrlL.
, (3) Insulating film Al(H2PO+)s Crys
-: Conducted under the following conditions: 1D idal silica system, coating amount 3 fl/ms.

As is clear from the results shown in Figure 1, the iron loss (w17150 (W/yu)) value after flattening was 1.18, but after laser beam irradiation treatment, it became 1.
It drops drastically to 00.

However, the temperature (
It can be seen that the iron loss value after insulation coating treatment changes greatly depending on the plate temperature), and that the effect deteriorates extremely when the plate temperature exceeds 600°C.

For this reason, the temperature during the insulation coating treatment was limited to 600°C or less.

Among these, the best option is to perform the baking process at a board temperature of 550°C or less, which makes it possible to make the iron loss after insulation coating treatment equal to or lower than that after laser beam irradiation treatment. .

What is also worth mentioning is that the insulation film treatment is performed at a board temperature of 500℃.
As described below, the iron loss after the insulation coating treatment is improved more than the iron loss after the laser beam irradiation treatment.

The reason for this is not clear at present, and this is a totally unexpected effect.

The laser beam irradiation used in carrying out the present invention is not limited in any way, and may be, for example, continuous linear irradiation, dotted irradiation, broken line irradiation, or the like.

Further, the laser used is not particularly limited, and may be either continuous or pulsed.

Further, the direction of irradiation on the electrical steel sheet can be one or a combination of the rolling direction (L), the direction perpendicular to the rolling direction (C), and the intermediate directions.

Now, to show one application example when using a pulsed laser beam, the energy density P is 0.01 to 100O
The diameter d for laser beam irradiation which is J/i is 0.0
It has trace rows of 1 to 1 rtm approximately parallel to the C direction of the steel plate with a distance between the centers of the traces of 0.01 to 2 mm, and the distance of the trace rows in the L direction is 1 to 30 n for the time of the loser pulse. The width is set to 1 ns to 100 m5.

Further, the irradiation treatment may be performed on either one side or both sides.

One implementation step in the method of the present invention is to finish the electromagnetic steel coil coated with an annealing separating agent, annealing it at a high temperature, removing the excess separating agent according to a conventional method, and then flattening it at 700 to 900°C. The steel plate surface is subjected to laser beam irradiation treatment, and then the plate temperature is lower than 600℃, preferably 55℃.
This is a method of performing the insulation coating treatment at a temperature of 0°C or lower, more preferably 500°C or lower.

The electromagnetic steel sheet subjected to the laser beam irradiation treatment according to the present invention has a remarkable improvement in core loss.

As a result, the first characteristic is that the tension effect of the insulation coating, which was conventionally implemented industrially, is no longer necessary, and an inexpensive treatment agent can be used in place of the expensive insulation coating treatment agent containing colloidal silica. Become.

Also, thick coating is unnecessary unless a particularly high resistance is required.
A thin coating of 3 g/m is possible, and as a result, the space factor when laminated is improved, and there is no peeling of the film during slitting or shearing, resulting in improved workability.

Secondly, the tension effect caused by the glass film (forsterite) produced by annealing is no longer necessary, and therefore the annealing separation agent applied before annealing is not limited to one containing magnesia as its main component; Al2 not formed
It also becomes possible to use O3-based separation agents.

Thus, the absence of the glass film further improves the space factor and workability.

Thirdly, when final finish annealing is performed in a batch manner, conventionally, after sufficient secondary recrystallization, an even longer annealing time is required for purification treatment in order to improve iron loss. Ta.

On the other hand, according to the present invention, it is possible to improve the iron loss by laser beam irradiation treatment of the finish annealed steel plate, so it is sufficient that excellent magnetic flux density can be obtained by secondary recrystallization in the finish annealing. Therefore, it is possible to shorten the batch annealing time.

As a result, the energy saving effect is large and it can greatly contribute to cost reduction.

As a manufacturing method for electrical steel sheets without glass coating, the above A
In addition to using l2O3-based separation agents, there is also a method of removing the glass film by pickling, but by performing laser beam irradiation treatment after removing the glass film, there is not only a glass film but also an oxide film on the steel sheet surface. , is even more effective.

The above has mainly described the case where the final finish annealing is batch coil annealing, but in recent years, attempts to perform the final annealing by continuous annealing have already been proposed in order to save energy (for example, Japanese Patent Publication No. 48-3923). .

Since such a step does not require an annealing separator, an electrical steel sheet without a glass coating can be obtained, and the desired effect can be obtained by implementing the method of the present invention on the electrical steel sheet.

If there is no glass film for both batch coil annealing and continuous annealing, the steel plate surface is blued to create a thin oxide film, which improves laser beam absorption and enables efficient laser beam irradiation. .

The bluing process can be carried out on the outlet side of the flattening line in the case of batch coil annealing, or on the outlet side in the case of continuous annealing.

The bluing treatment can usually be carried out at a temperature of 600° C. or higher in air or by blowing steam into a mixture of N2 or N2+N.

Incidentally, instead of the oxide film formed by this bluing treatment, another laser beam absorbing agent may be applied.

For example, coating with a chromic acid solution or thin plating with Cu or the like may be used.

After laser beam irradiation treatment, the treatment liquid for insulating film treatment at a plate temperature of 600°C or less is mainly composed of a treatment liquid containing one or more of phosphates and chromates, and colloidal silica. , colloidal alumina, titanium oxide, and boric acid compounds.

In addition, as a reducing agent for chromate, polyhydric alcohol,
Contain one or more organic compounds such as glycerin and other organic compounds, water-soluble or emulsion resins to improve processability, high resistance, and organic resin powders with a particle size of 1μ or more to improve processability. I can do it.

This method of forming an insulating film by irradiating ultraviolet rays can also be adopted.

Example l Si2.9%, C0,003%, Mn 0.080%
.

Unidirectional electrical steel sheet containing Ai, 0.31% (0.30
%) was produced by the following steps.

The hot coil is cold-rolled and annealed once, then coated with magnesia, dried, wound into a coil, finished annealed at 1159°C for secondary recrystallization, and then excess magnesia is removed to produce steel with a glass coating. Heat the band to 850℃ x 70 Sec
flattened.

Samples were taken from the unidirectional electrical steel strip thus obtained, subjected to the following treatments, and tested for mechanical properties.

A treatment: Same as flattening B treatment: After flattening, laser beam irradiation treatment (1) Laser beam irradiation conditions: Energy density: 15 J/i Dotted trace diameter 20, 1 Distance between centers of dotted traces in C direction: 0.5 urn trace spacing in the direction of rows 2 10 mm C treatment: After laser beam irradiation treatment, insulation coating treatment (1) Laser beam irradiation conditions 2 Same as B treatment.

(2) Insulating film treatment (a) Treatment liquid = 20% colloidal silica 1oocc50
% aluminum phosphate 60CC CrO36 & boric acid 2g (b) Baking temperature (plate temperature): 500°C, 600°C.

700°c, soooC (c) Application amount: 3. Og/m'' E treatment (conventional method): The treatment liquid used in the C treatment of Example 1 was applied before the flattening treatment and baked at the same time as the flattening.

Application amount 5,5 g/n.

The results of the above tests are shown in Table 1.

As is clear from Table 1, the laser beam irradiation treatment was performed after flattening.

Products treated with insulation coating at temperatures below 600'C (plate temperature) have improved iron loss and magnetostriction properties compared to those treated with conventional methods, and in particular, products baked at temperatures of 500°C remain B-treated. Iron loss is better than that of

Furthermore, according to the method of the present invention, the amount of insulation film applied can be reduced compared to the conventional method (method of the present invention 3J/rn', conventional method s,
5 g/m), the improvement in adhesion and the space factor are remarkable.

Example 2 Si3.2%, CO,OO3%, Mn0.065%,
A unidirectional electrical steel sheet containing SO, 020% and A70.004% was manufactured by the following process.

After cold rolling twice and annealing twice, the hot coil was coated with magnesia, dried, and wound into a coil.

Thereafter, final annealing was performed at 1180°C to perform secondary recrystallization.

This final annealed coil was divided into two parts, excess magnesia was removed from one part, and the steel plate having the glass film was flattened at 870°C for 80 seconds in an N2 atmosphere.

The remaining half was subjected to flattening at 870°C for 80 seconds in a N2 atmosphere after removing the glass film with 25% HCl (liquid temperature: 80°C).

Since there was no glass film, the surface was completely blued.

Samples were taken from this image-treated material, subjected to the following treatments, and characterized.

G-treated 2nd F with flattening with F-treated Nigelas film
Laser beam irradiation treatment after treatment (1) Laser beam irradiation treatment conditions: Energy density: 13 J/ff1 Dot-like trace diameter: 0.15 Dot-like mark C direction center distance: 0.5 mm Trace array direction spacing near 65 dishes Insulating coating treatment after H treatment and F treatment (1) Insulating coating treatment conditions (a) Treatment liquid CrO310g Mg03g Glycerin
1g Emulsion type acrylic resin 4g (b) Baking conditions: Board temperature 300℃ (c) Coating amount: '; 81/rrt ■ Processing: F treatment, laser beam irradiation treatment, insulation film treatment (1) Laser beam irradiation treatment conditions 2 Same as G processing (2
) Insulating coating treatment conditions: Same as H treatment J treatment No Nigelas coating Treatment with bluing coating as is: ■ Insulation coating treatment after treatment (1) Insulation coating treatment conditions: Same as H treatment L treatment: Laser beam irradiation after J treatment Insulating film treatment after treatment (1) L/- Surbeam irradiation treatment conditions: Same as G treatment (
2) Insulating film treatment conditions: Same as H treatment M treatment: ■ Laser beam irradiation treatment after treatment (1) Laser beam irradiation treatment conditions Same as 20 treatment.

The results of the above tests are shown in Table 2.

As is clear from Table 2, both the ■ treatment (with glass film) and the L treatment (without glass film, with bluing film) were treated with insulation film after laser beam irradiation treatment (board temperature 300
℃, zg/m) had better iron loss than those treated with laser beam irradiation (G treatment), and those with glass coating and insulating coating treatment (N treatment) and Of course, the iron loss characteristics were significantly improved compared to those treated with an insulating film after bluing treatment (K treatment), as well as those treated with the conventional method (N treatment), and Since the amount of insulating film can be reduced compared to the N treatment (conventional method), both the adhesion and the space factor of the film are much better than the M treatment.

Example 3 Si 3.0%, acid soluble A 10.015%, 80.00
A hot-rolled sheet with a thickness of 2.3% containing 2% was cold rolled to a thickness of 104%, and intermediate annealing was performed at 820°C for 5 minutes.
Cold rolled to 0% finished plate thickness, decarburized annealed at 850°C for 3 minutes, then continuously annealed in dry hydrogen at 1000°C for 5 minutes, treated with laser beam irradiation on the exit side, and then treated with insulation coating. Liquid 311/m was baked at a plate temperature of 500°C.

Thus W17150 1.40W/kg, B1゜1.
An electromagnetic steel sheet was obtained which had a magnetic property of 81T, an insulation resistance of 520 Ω-d/sheet, an adhesion of 20 gmφ, and a film property of a space factor of 99.0%.

As a comparative example, when the same material was used and laser beam irradiation was performed under the same conditions and the subsequent steps were discontinued, the magnetic properties of the obtained electrical steel sheet were W171501.47W/ky
, Blol, 81T.

(1) Laser beam irradiation treatment conditions: Energy density 15 J/crA Point trace diameter 0.1 rtw Trace C direction center distance 0.5 order Interval in trace direction: 10g lightning (2) Insulating film treatment liquid: Same as C treatment in Example 1.

Example 4 C0,046%, Si2.96%, Mn 0.083
%.

80.025%, l'40.028%, NO,007
%.

Finish annealing the slab consisting of the remaining iron and impurities according to a known process, namely hot rolling → hot rolled plate annealing → cold rolling (0.35% thickness) → decarburization annealing - + MgO coating → finishing annealing → heat flattening. After the glass film on the surface of the steel plate was removed with hydrofluoric acid, it was made into a mirror surface by chemical polishing.

This steel plate was subjected to a laser beam irradiation treatment, and then an ultraviolet-curable insulating film was applied and the film was cured by ultraviolet irradiation.

Laser beam irradiation treatment conditions: Energy density 15 J/i Dotted trace diameter o, 15 dotted marks C direction distance between centers 0.5 mm Trace array direction spacing 5 mm The unidirectional electrical steel sheet obtained in this way Magnetism is as follows.

Example 5 Si3.0%, C0,003%, Mn0.075%.

Unidirectional electrical steel sheet containing AlO, 03% (0,30
關) was manufactured by the following process.

The hot coil is cold-rolled and annealed once, then coated with magnesia, dried, wound up into a coil, finished annealed at 1150°C for secondary recrystallization, and then excess magnesia is removed to form a copper strip with a glass coating. was flattened at 850°C for 70 seconds.

Samples were taken from the unidirectional electrical steel strip thus obtained, subjected to the following treatments, and tested for mechanical properties.

0 treatment: Same as flattening P treatment: After flattening, continuous laser beam irradiation treatment *(1) Laser beam irradiation conditions (i) Power: 2.0 W (II) Inside irradiation trace; 02 Homo (iii) Trace row Directional spacing; 5-4v) Irradiation speed: 2001 nm /5ecR treatment: Insulating film treatment after P treatment (1) Insulating film treatment ([) Treatment liquid; 20% colloidal silica 1oocc5
0% aluminum phosphate 60cc CrO36g Boric acid 2g (ii) Baking temperature (plate temperature); 500°C (iii) Coating amount: 3. O&/m was carried out as described above and the results are shown in Table 4.

As described above, according to the present invention, an electrical steel sheet that has been subjected to secondary recrystallization annealing is subjected to a laser beam irradiation treatment, and then the plate temperature is set in a temperature range of 600°C or lower, preferably 550°C or lower, and more preferably 500°C or lower. By applying the insulation film treatment, it is possible to stably and significantly improve the core loss value.

Moreover, as a result, it becomes possible to omit the glass film and apply a thin insulation film, which reduces magnetostriction, improves the adhesion of the insulation film, and improves the space factor.It also makes it possible to shorten the process, making it possible to reduce the magnetostriction, and to apply thinner insulation films. This greatly contributes to the upgrading of the industry and the relaxation of operating conditions.

It should be noted that although the above explanation has mainly been made regarding the case of grain-oriented electrical steel sheets, it goes without saying that the same effects can be achieved even when the present invention is applied to non-oriented electrical steel sheets.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between insulation film treatment temperature and iron loss.

Claims (1)

[Claims of Claims] 1. The surface of a finish-hardened electromagnetic steel sheet is subjected to a laser beam irradiation treatment to produce laser marks, and then an insulation coating treatment is performed at a temperature range not exceeding 600°C. Processing method for electrical steel sheets. 2. The method according to claim 1, wherein the insulation coating treatment is performed at a plate temperature of 550°C or less. 3. The method according to claim 1, wherein the insulation coating treatment is performed at a board temperature of 500°C or less. 4. The method according to claim 1, wherein a laser beam irradiation treatment is performed on the surface of an electromagnetic steel sheet on which a glass film is not formed. 5 Claim 1 in which a laser beam irradiation treatment is applied to the surface of an electromagnetic steel sheet on which a laser beam absorbing film is formed.
The method described in section. 6. A patent claim in which an annealing separator that does not contain a glass film-forming component is applied and wound into a coil, and after finishing annealing by a batch coil annealing method, a laser beam irradiation treatment is performed on the surface of the heat flattened electrical steel sheet. Range 4th
The method described in section. 7. The method according to claim 4, wherein a laser beam irradiation treatment is performed on the surface of an electrical steel sheet that has been finish annealed by a continuous annealing method. 8. Claim 5, in which an oxide film is formed on the surface of an electrical steel sheet subjected to bluing treatment on the exit side of heat flattening treatment after finish annealing by batch coil annealing method.
The method described in section. 9. The method according to claim 5, wherein an oxide film is formed on the surface of the electrical steel sheet which has been blued on the exit side of the finish annealing by continuous annealing. 10. The method according to claim 1, which uses an insulating film composition that does not contain a glass film-forming component.