JPH0686648B2 - Non-oriented electrical steel sheet with excellent magnetic properties - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a non-oriented electrical steel sheet having a low iron loss and a high magnetic flux density.

(Prior Art) A non-oriented electrical steel sheet is a soft magnetic material mainly used as a core material of a motor or a transformer. In order to increase the efficiency of these electric devices, the soft magnetic material used is required to have low iron loss and high magnetic flux density. In particular, in order to meet the recent strong demand for energy saving and miniaturization of equipment, it is necessary to develop a material having a higher magnetic flux density than before while keeping iron loss low. However, it is extremely difficult to achieve both low iron loss and high magnetic flux density. Conventionally, as a method of reducing iron loss, it is generally performed to increase the Si content and increase the specific resistance of the steel sheet, but the magnetic flux density also decreases as the Si content increases. On the other hand, a non-oriented electrical steel sheet having a low Si content has a relatively high magnetic flux density but also a high iron loss.

Japanese Patent Publication No. 61-4892 discloses a method for producing a non-oriented electrical steel sheet having a low iron loss and a high magnetic flux density by containing 0.6 to 3.0% of Al in a steel having a Si content of 0.2% or less. Is proposed. Al is known to increase the specific resistance of the steel sheet and reduce the iron loss like Si, but according to the present invention, Al has the effect of further improving the texture and increases the magnetic flux density. is there. However, for this purpose, a large amount of Al, which is 0.6% or more, must be contained, so that there is a problem that the manufacturing cost increases. Moreover, the amount of decrease in iron loss and the amount of increase in magnetic flux density are small in spite of the addition of a large amount of Al.

Furthermore, in JP-A-2-61031, the Si content is set to 0.1%.
0.1 to 1.0% Al and 0.02 to 0.15% Sn in the steels suppressed below
Has been proposed for producing a non-oriented electrical steel sheet having a low iron loss and a high magnetic flux density by adding a combination of Al and Fe. In addition, JP-A-2-66
Japanese Patent No. 138 discloses that the steel with the Si content suppressed to 0.1% or less, 0.
A method of producing a non-oriented electrical steel sheet having a low iron loss and a high magnetic flux density by adding 1 to 1.0% of Al and 0.1 to 0.25% of P in combination has been proposed. However, the non-oriented electrical steel sheets obtained by these methods are not sufficiently effective in improving the magnetic properties.

(Problem to be Solved by the Invention) An object of the present invention is to provide a non-oriented electrical steel sheet having low iron loss and high magnetic flux density that enables energy saving and downsizing of electric devices.

(Means for Solving the Problems) As a result of detailed investigation of the influence of various alloying elements on the magnetic flux density of the high Al-added steel, the present inventors have found that the high Al steel with the Si content reduced as much as possible has an appropriate amount. It has been found that by adding P and Sb in combination, a remarkable increase in magnetic flux density can be obtained, which cannot be obtained with a mere high Al steel or a high Al steel containing P alone.

Here, the present invention is "wt%, C: 0.005% or less, Si: 0.1%
Below, Mn: 0.1% or more and 0.7% or less, P: 0.05% or more and 0.2%
Below, S: 0.01% or less, Al: over 0.3 and 2.0% or less, Sb: 0.01
% And 0.30% or less, the balance being Fe and unavoidable impurities, and the non-oriented electrical steel sheet having excellent magnetic properties ”is summarized.

The non-oriented electrical steel sheet of the present invention has a low iron loss and a high magnetic flux density mainly due to the synergistic effect of P and Sb. Both P and Sb are known as elements that segregate at the grain boundaries, and it is presumed that some interaction of these two elements with respect to segregation at the grain boundaries leads to improvement of the texture and increases the magnetic flux density. To be done. Incidentally, Japanese Patent Laid-Open No. 59-100217 discloses a non-oriented electrical steel sheet of high Al steel containing Sb. It is disclosed in this publication that the magnetic flux density increases when Sb and P are added in combination. It has not been.

(Function) The function and effect of the alloying element in the non-oriented electrical steel sheet of the present invention and the reason why the content thereof is limited as described above will be described below.

C: C is an element that forms carbides and adversely affects the magnetic properties, so it is desirable to keep the content as low as possible. In particular, 0.005% or less is desirable to prevent magnetic aging, and 0.003% or less is desirable to complete the prevention.

Si: Si is an effective element that increases the specific resistance of the steel sheet to reduce eddy current loss and reduce iron loss. It However, Si decreases the magnetic flux density on the other hand, so addition of a large amount is not preferable. Si
Is less than 0.1%, there is no problem that the magnetic flux density decreases.

Mn: Mn has the effect of preventing hot brittleness of the steel sheet. But 0.
If it is less than 1%, this effect is small, and if it exceeds 0.7%, the magnetic flux density decreases, so the content should be 0.1 to 0.7%.

P: P is an important element that increases the magnetic flux density by the combined addition of Sb in the present invention. This effect appears from 0.05%, but if it exceeds 0.2%, the steel plate becomes brittle, so 0.05 to 0.2%
Content.

S: S forms fine sulfides to suppress crystal grain growth, and the sulfides themselves impede domain wall movement, deteriorating magnetic properties, and especially increasing iron loss. Therefore, keep the content as low as possible. Is desirable. 0.01% or less, preferably 0.
If it is kept below 006%, the above adverse effects can be avoided.

Al: Al is an important element that contributes to both low iron loss and high magnetic flux density. If it is less than 0.3%, not only the specific resistance of the steel sheet is low and the iron loss is not reduced, but also the effect of improving the texture is small, so the magnetic flux density becomes low. On the other hand, if the content exceeds 2.0%, the iron loss becomes low, but the magnetic flux density becomes low, and desired magnetic characteristics cannot be obtained. From this, the content of Al is 0.
More than 3% and 2.0% or less.

Sb: Sb is an important element that increases the magnetic flux density. Sb exists in a solid solution state and is easily segregated at grain boundaries. It is considered that Sb segregated at the grain boundaries improves the texture due to the interaction with P and the magnetic flux density increases. The effect of this Sb is 0.01
Although it appears from the content of more than 0.3%, if the content exceeds 0.30%, the effect is saturated and only the price rises.

In addition to the above-mentioned components, the content of carbonitride forming elements such as Ti, Zr, Nb, and V mixed as impurities in addition to the above components should be kept as low as possible in order to increase iron loss due to poor crystal grain growth due to fine precipitates. It is desirable for prevention.

The electrical steel sheet of the present invention having the above composition can be manufactured by a general non-oriented electrical steel sheet manufacturing process. For example, the following manufacturing method is used.

After heating the slab of the raw material to a predetermined temperature, hot rolling is performed to obtain a hot rolled sheet. The slab heating temperature in this hot rolling process is 1100 to 1250 ° C, and the finishing temperature of hot rolling is 750 to 950 ° C.
Is desirable. Winding after hot rolling is desirable to be performed at a temperature of 600 ° C or higher, but from the viewpoint of descaling of the steel sheet,
You may wind at low temperature below 0 degreeC. Note that the slab heating step can be omitted in the case of adopting direct feed rolling in which the hot cast slab recently cast, which has recently been performed from the viewpoint of energy saving, is immediately subjected to hot rolling.

Then, the hot rolled sheet is subjected to cold rolling. At this time, in order to improve the magnetic properties by recrystallization of the worked structure and coarsening of crystal grains, hot-rolled sheet annealing may be performed before cold rolling. The temperature of hot-rolled sheet annealing is 680 to 900 when performing box annealing.
In the case of continuous annealing at 75 ° C, 750-1100 ° C is suitable.
The cold rolling may be any one of the cold rolling method once or the cold rolling method two or more times with intermediate annealing interposed therebetween. After cold rolling, recrystallization and grain coarsening are performed by finish annealing. Further, if it is used as a semi-processed electromagnetic steel sheet, it may be subjected to cold rolling with a reduction rate of 3 to 15% after finish annealing to obtain a final product.

(Examples) Steel slabs having the compositions shown in Table 1 were cast, these slabs were heated to 1150 to 1200 ° C, and then finished at a finishing temperature of 800 to 850 ° C.
It was hot rolled to a thickness of 2.3 mm. After the hot rolling, it was wound under the conditions shown in the same table, subjected to hot rolled sheet annealing, cold rolling and finish annealing to obtain a non-oriented electrical steel sheet. However, No. 8 to 14 were only pickled and not hot-rolled sheet annealed.

Thereafter, test pieces were cut out from these non-oriented electrical steel sheets and the magnetic properties were measured. The measurement results are also shown in the same table.

In Table 1, Test Nos. 1 to 7 have almost the same composition except for the Al content, and have the same manufacturing conditions. Test Nos. 8-11
Except for the Sb content, the composition is almost the same and the manufacturing conditions are the same. Test Nos. 12 to 14 have almost the same composition except for the P content and have the same manufacturing conditions. Test Nos. 15 to 17 are almost the same except for the contents of Si and S, and the manufacturing conditions are also the same. Test Nos. 18 and 19 have almost the same composition as No. 4 except for the Mn content, and have the same manufacturing conditions. No. 20 has almost the same composition as No. 4 except for the C content, and has the same manufacturing conditions.

As can be seen from the test results in Table 1, all the examples of the present invention have magnetic characteristics of low iron loss and high magnetic flux density. On the other hand, a comparative example in which any one of the components is out of the range specified by the present invention is inferior in one or both of the core loss and the magnetic flux density.

(Effects of the Invention) As shown in the examples, the non-oriented electrical steel sheet of the present invention is excellent in both core loss and magnetic flux density. Therefore, it can be said that the non-oriented electrical steel sheet of the present invention is an extremely excellent material for achieving downsizing of equipment and energy saving.

Claims (1)

[Claims] [Claim 1] C: 0.005% or less, Si: 0.1% or less, Mn: 0.1% or more and 0.7% or less, P: 0.05% or more and 0.2% or less, S: 0.01% or less, Al: 0.3 Over 2.0%, Sb: 0.01%
The above is 0.30% or less, and the balance is Fe and inevitable impurities.