JPH0826440B2 - Non-oriented electrical steel sheet and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a non-oriented electrical steel sheet having excellent magnetic properties and a method for producing the same.

Conventional technology Non-oriented electrical steel sheets are often used in rotating machines such as generators and electric motors.

This non-oriented electrical steel sheet is generally obtained by subjecting a silicon steel slab produced by an LD converter with extremely few impurities and inclusions to the steps of hot rolling → pickling → cold rolling → continuous annealing → surface treatment. Being manufactured.

Conventionally, in order to manufacture a non-oriented electrical steel sheet having excellent magnetic properties, it has been said that it is effective to carry out hot rolling and then to anneal the hot rolled steel sheet to coarsen the crystal grains.

In the case of full process, the annealing is finish continuous annealing,
In the case of the semi-process, crystal grains were coarsened by strain relief annealing.

Then, it is effective to reduce the amount of non-metallic inclusions such as oxides, nitrides, and sulfides that hinder the growth of crystal grains as much as possible, or to coarsen them to render them harmless. For example, in a method for producing a high Si steel sheet, a method of obtaining a steel sheet with low iron loss by suppressing S, N and O in the material (Japanese Patent Laid-Open No. 59-74223).
Japanese Patent Laid-Open Publication No. 60-141829).

However, all of the conventional non-oriented electrical steel sheets with excellent magnetic properties are expensive.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As described above, the improvement of the magnetic properties of the conventional non-oriented electrical steel sheet has been performed without considering the cost reduction. In view of such a current situation, it is an object of the present invention to provide a non-oriented electrical steel sheet having improved magnetic characteristics while reducing costs.

Since the inventor produced a non-oriented electrical steel sheet with poor magnetic properties, while searching for the cause, he realized that the contained trace elements had an effect, and As a result, in the region where solAl in steel is extremely low,
It was found that C, N and V should be suppressed. Based on this finding, the present invention has completed a non-oriented electrical steel sheet having a steel component containing almost no Al and excellent in the growth of crystal grains, and a method for producing the same.

Means for Solving the Problems In order to achieve the above object, the non-oriented electrical steel sheet of the present invention is C0.01 wt% or less, Si1.0 wt% or less, Mn1.0 wt%
SolAl 0.005 wt% or less, N 0.005 wt% or less, V0.0
The content is 1% by weight or less, and [N] [V] ≦ 1 × 10 ⁻⁵ is satisfied, and the balance is iron and inevitable impurities.

Further, in the method for producing a non-oriented electrical steel sheet, after pickling a hot-rolled steel strip obtained by subjecting a silicon steel slab having the above-mentioned composition to ordinary hot rolling, followed by cold rolling to a predetermined plate thickness. After that, a continuous continuous annealing is performed at 650 to 900 ° C.

In the above, the hot-rolled steel strip may be annealed at 600 to 1000 ° C and pickled.

Effect Since the non-oriented electrical steel sheet of the present invention suppresses the content of C, N, and V in the region where solAl is extremely small, the formation of vanadium carbonitride that inhibits the growth of crystal grains is small. As a result, the coarse crystal grains necessary for obtaining excellent magnetic characteristics can be easily obtained.

The chemical composition of the non-oriented electrical steel sheet of the present invention is limited for the following reasons.

C causes magnetic aging and causes deterioration of magnetic properties.
It was set to 01% by weight or less.

Si is an essential element for reducing iron loss, but such solAl
In the region, if Si exceeds 1.0% by weight, the grain growth property deteriorates, so the content was made 1.0% by weight or less.

Mn is also an element effective in reducing iron loss, but excessive addition exceeding 1.0 wt% causes a decrease in the A ₃ transformation point and the texture after hot rolling is disadvantageous to the magnetic properties, so 1.0% by weight or less And

It is said that solAl has a great influence on the growth of crystal grains, and that a steel sheet having large magnetic grains having excellent magnetic properties contains little or excessive solAl (about 0.3% by weight). In the case of excessively containing solAl, Al is more likely to bond with N than V which is a harmful precipitate, so that harmful VN is not precipitated. Moreover, it is rendered harmless as a coarse precipitate of Al N. However, excessive addition of Al increases the anisotropy of magnetic properties, which is not desirable as a non-oriented electrical steel sheet, and causes a cost increase. So solAl
Was limited to a range of 0.005% by weight or less, which hardly contained.

Since N and V prevent precipitation of vanadium carbonitride, which is detrimental to magnetic properties, it is desirable that the amounts are small. FIG. 1 shows the V-N solubility curve at 750 ° C. and the relationship between the V and N contents and the magnetic properties when C is 0.01% by weight or less. From this figure, the magnetic characteristics are excellent in the range below the VN solubility curve at 750 ° C. And N is 0.005% by weight
Beyond 0.005, other fine precipitates are formed and harmful, so 0.005
It is limited to less than or equal to weight%. Further, V satisfies the lower region of the VN solubility curve shown in FIG. 1 in relation to N, that is, [V] [N] ≦ 1 × 10 ⁻⁵ , and is set to 0.01% by weight or less.

The annealing temperature of the hot-rolled steel strip in the manufacturing process is sufficient if it is equal to or higher than the recrystallization temperature of the hot-rolled steel strip, and usually 600 to 1000 ° C.

For continuous continuous annealing, it is sufficient if the recrystallization temperature is higher than 650.
It should be ~ 900 ℃.

Examples Example 1 By the practice of this invention, C0.003 wt%, Si0.3 wt%, Mn0.3 wt%, solAl <0.001 wt%, N0.002 wt%, V0.004 wt%, balance substantially A silicon steel slab consisting of Fe (referred to as Invention 1) and C0.003% by weight, 0.3% by weight Si, 0.3% by weight Mn, solAl <0.001% by weight, for comparison.
A silicon steel slab (0.001% by weight, V0.014% by weight, the balance consisting essentially of Fe) (referred to as Comparative Example 1) was subjected to normal hot rolling to obtain a sheet width of 1000 mm and a sheet thickness of 2.3 mm. Got a steel strip. Then, after being pickled, cold rolling was applied to finish the plate thickness to 0.5 mm, and further finish continuous annealing was performed under the condition of soaking at 720 ° C. for 1 minute.

Example 2 A hot-rolled steel strip having the same composition as in Invention 1 of Example 1 (referred to as Invention 2) and a hot-rolled steel strip having the same composition as that of Comparative Example 1 in Example 1 (referred to as Comparative Example 2) were acidified. After washing, hot-rolled steel sheet was annealed under the condition of 680 ° C x 20 hours.

Then, after pickling, cold rolling is applied to a plate thickness of 0.5 m.
After finishing to m, it was further subjected to finish continuous annealing under the condition of soaking at 720 ° C for 1 minute.

Example 3 C 0.007% by weight, Si 0.7% by weight, Mn 0.7% by weight, solAl <
0.003% by weight, N0.001% by weight, V0.008% by weight, the balance being a silicon steel slab consisting essentially of Fe (referred to as Invention 3) and C0.007% by weight, Si0.7% by weight for comparison. 0.7% by weight of Mn, solAl <0.003% by weight, 0.01% by weight of N, 0.0027% by weight of V, and the remainder being substantially Fe (silicon steel slab (Comparative Example 3
Is referred to as), and is subjected to normal hot rolling to obtain a plate width of 1000 mm and a plate thickness of 2.
A 3 mm hot rolled steel strip was obtained. Then, the hot-rolled sheet is annealed under the condition of soaking for 950 ° C for 3 minutes, pickled, and then cold-rolled to finish the thickness of 0.5 mm, and the continuous finishing under the condition of soaking for 820 ° C for 1 minute. It was annealed.

Example 4 C 0.002% by weight, Si 0.1% by weight, Mn 0.5% by weight, solAl <
0.001% by weight, N0.004% by weight, V0.002% by weight, the balance being a silicon steel slab consisting essentially of Fe (referred to as Invention 4), and for comparison C0.002% by weight, Si0.1% by weight, 0.5% by weight of Mn, <0.001% by weight of solAl, 0.004% by weight of N, 0.018% by weight of V, and the remainder being substantially Fe (silicon steel slab (Comparative Example 4
Is referred to as), and is subjected to normal hot rolling to obtain a plate width of 1000 mm and a plate thickness of 2.
A 3 mm hot rolled steel strip was obtained. Then, after being pickled, it was cold-rolled to a plate thickness of 0.5 mm, and further subjected to finish continuous annealing under the conditions of soaking at 690 ° C for 1 minute.

Samples were taken from the respective electromagnetic steel sheets produced by the respective manufacturing methods of Examples 1 to 4 as described above while the Epstein test was cut as a full process material, and subjected to strain relief annealing under the conditions of 750 ° C. × 2 Hr. It was measured as a process material and the iron loss was examined. The results are shown in Table 1 in comparison with each other.

From the above results, it is understood that the iron loss of the present invention is improved and the magnetic characteristics are excellent in comparison between the present invention and the comparative example for each example.

EFFECTS OF THE INVENTION The present invention makes it possible to obtain a non-oriented electrical steel sheet having excellent magnetic properties without increasing the cost, by controlling the content of C, N, and V to a low level in a range containing almost no Al. it can.

[Brief description of drawings]

Fig. 1 shows V in the range where the C content is 0.01% by weight or less.
FIG. 7 is a graph showing the relationship between −N solubility curve (at 750 ° C.), V and N contents, and magnetic properties.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area H01F 1/16

Claims (2)

[Claims] 1. C 0.01 wt% or less, Si 1.0 wt% or less, Mn
Contains 1.0 wt% or less, sol Al 0.005 wt% or less, N 0.005 wt% or less, V 0.01 wt% or less, and [N]
A non-oriented electrical steel sheet that satisfies [V] ≦ 1 × 10 ⁻⁵ ([N], [V] represents the weight% of each element), and the balance is iron and inevitable impurities. 2. C 0.01 wt% or less, Si 1.0 wt% or less, Mn
Contains 1.0 wt% or less, sol Al 0.005 wt% or less, N 0.005 wt% or less, V 0.01 wt% or less, and [N]
[V] ≦ 1 × 10 ⁻⁵ is satisfied, the rest is a silicon steel slab consisting of iron and unavoidable impurities, and the hot-rolled steel strip obtained by normal hot rolling is pickled and then cold rolled. A method for producing a non-oriented electrical steel sheet, which comprises subjecting the sheet to a predetermined sheet thickness and further performing continuous annealing at 650 to 900 ° C.