JPH0819466B2 - Non-oriented electrical steel sheet manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for producing a semi-process non-oriented electrical steel sheet, which is premised on that the material is punched and sheared by a customer, and then stress relief annealing is performed, and the punching. The present invention relates to a method for manufacturing a non-oriented electrical steel sheet including a shearing process and a strain relief annealing process.

[Conventional technology]

In recent years, due to the social demand for energy saving, there is a demand for improving the efficiency of small motors used in refrigerators, coolers, etc., downsizing fluorescent lamp ballasts, and preventing temperature rise. There is a strong need for high magnetic flux density and low iron loss for grain-oriented electrical steel sheets.

Against this background, in recent years, there has been a demand for a so-called lower non-oriented electrical steel sheet with Si ≦ 1.0%, which has a relatively high iron loss but a high magnetic flux density at a low cost, and a demand for the reduction of the iron loss. It is increasing. As a material for lowering iron loss of such a low-grade non-oriented electrical steel sheet, there is a semi-processed material in which a steel sheet is punched / sheared by a customer and then strain relief annealing is performed. This semi-processed material has the following (1),
It is roughly divided into (2).

(1) After the primary cold pressure and annealing, the secondary cold pressure that is adjusted to about 1-10% is punched and sheared by the customer, and then strain relief annealing is performed. Process material. This steel sheet is intended to reduce the iron loss by coarsening the crystal grains during strain relief annealing by strain grain growth due to pressure-controlled strain, but at the same time, it has the drawback that the magnetic flux density is also reduced.

(2) A semi-processed material that is cold-rolled and annealed once like the full-processed material, punched and sheared by the customer, and then stress-relieved and annealed by a single cold pressure (processwise Since the full process material will be annealed again by the customer, it will be referred to as "full process annealing material" for convenience hereinafter. Although this steel sheet has a smaller loss of iron loss than the one obtained by twice cold pressing, it has an advantage that the magnetic flux density does not decrease so much.

Of these, the demand for full-process annealed material (2), which is advantageous in terms of magnetic flux density, has rapidly increased in addition to the conventional semi-processed material (1) from the viewpoint of downsizing and high efficiency of equipment. . In the case of such a full-process annealed material, it is a problem to improve the iron loss, which is inferior to the semi-processed material due to (2) 2 cold pressure, without deteriorating the magnetic flux density.

Conventionally, the following techniques have been disclosed for improving iron loss or magnetic flux density of a full process annealed material.

First, there are the following technologies in consideration of the manufacturing process.

(A) Japanese Unexamined Patent Publication No. 57-35628: Technology for short-time annealing of hot-rolled sheet (b) Japanese Unexamined Patent Publication No. 58-136718: Substitute for short-time annealing of hot-rolled sheet by self-annealing by ultra-high temperature winding (C) Japanese Patent Laid-Open No. 61-15920: A hot-rolled sheet finished and rolled at an Ar ₃ transformation point or higher is water-cooled to achieve a finer structure, which is then cold-pressed and annealed at a temperature as low as recovery annealing. By doing so, the structure remains fine, thereby improving the grain growth property during stress relief annealing. Further, there are the following techniques considering the component conditions. That is, these are techniques that improve the grain growth property during stress relief annealing in consideration of the components to increase the grain size after stress relief annealing and reduce iron loss.

(I) Prevention of precipitation of fine Al N that deteriorates grain growth property (d) JP-B-59-20731: B is added to Al ≦ 0.1% steel and N is fixed as BN, which has little adverse effect on grain growth. Technology (e) Japanese Patent Publication No. 62-49321: Same as above (f) Japanese Patent Publication No. 62-21849: Same as above (g) Japanese Patent Publication No. 58-55210: Technology to make Al ≤ 0.001% and to be substantially free of Al N (ii) Preventing precipitation of fine Mn S that deteriorates grain growth (h) Ultra-low S technology (i) Japanese Patent Laid-Open No. 63-103023: Al ≦ 0.002% Addition of Ca in steel and S has an adverse effect on grain growth Technology for fixing as Ca S with a small amount [Problems to be solved by the invention] As described above, various technologies have been proposed for improving the properties of conventional full-process annealed materials, but all of them have the following problems. Have a point.

First of all, considering the manufacturing process, (a) shows an increase in cost due to the addition of hot-rolled sheet annealing, and (b) shows an increase in scale due to ultra-high temperature winding and accompanying reduction in pickling ability, or grain boundary oxidation. The remarkable deterioration of the surface properties caused by the problem is a problem. In addition, in (c), in addition to the defective shape of the hot-rolled sheet due to water cooling, remarkable hardening due to low-temperature annealing causes a problem during punching and shearing. In this way, the modification of the manufacturing process still leaves many problems,
It's hard to say enough.

Further, in consideration of the components, all of (d) to (i) have Al ≦ 0.1% (substantially Al ≦ 0.0 from the examples etc.).
2%) steel, and for steel containing Al ≧ 0.1%, no useful technology has been found for improving its properties. Of course, in steels with Al ≧ 0.1%, it is not necessary to consider Al N because Al N precipitates relatively coarsely, but since Al greatly increases the specific resistance, a full process annealed material with low iron loss is produced. This is an element that should be utilized positively in this regard, and in this sense, improvement in the properties of Al ≧ 0.1% steel is desired.

In view of such circumstances, the present invention is to improve the characteristics of a full-process annealed material containing 0.1% or more of Al and a punching / shearing-strain relief annealed material using the full-process annealed material as a raw material, and particularly to improve iron loss. To aim.

[Means for solving the problem]

As a result of intensive studies on the improvement of the properties of the full process annealed material with Al ≧ 0.1%, the present inventors have attempted to optimize the P amount and the Mn, S amount, and Mn / S ratio. The present invention has been completed based on the new finding that magnetic properties and punching properties are improved when this is subjected to specific manufacturing conditions.

 That is, the configuration of the present invention is as follows.

(1) In a method for manufacturing a semi-process non-oriented electrical steel sheet in which stress relief annealing is performed after punching / shearing, in weight%, C ≦ 0.0050%, 0.06% ≦ Si ≦ 1.0%, 0.5% ≦ Mn ≦
1.5%, 0.01% ≤ P ≤ 0.06%, 0.010% ≤ S ≤ 0.030%,
Steel with 0.1% ≤ Al ≤ 0.5%, N ≤ 0.0050%, balance Fe and unavoidable impurities, and satisfying Mn (%) / S (%) ≥ 40, T ≤ 1.38 [Mn / S] + 1115 , Mn: Mn content (wt%) S: S content (wt%) After heating at a heating temperature T (° C) that satisfies the content, finish temperature Ar ₃
After the transformation point, hot rolling at a coiling temperature of 600 ℃ or more and 720 ℃ or less, then pickling and cold rolling, then 625 ℃ or more 800 ℃
A method for manufacturing a non-oriented electrical steel sheet, which comprises annealing at the following temperature.

(2) In a manufacturing method of a semi-process non-oriented electrical steel sheet in which strain relief annealing is performed after punching / shearing, C ≦ 0.0050%, 0.06% ≦ Si ≦ 1.0%, 0.5% ≦ Mn ≦
1.5%, 0.01% ≤ P ≤ 0.06%, 0.010% ≤ S ≤ 0.030%,
Steel with 0.1% ≤ Al ≤ 0.5%, N ≤ 0.0050%, balance Fe and unavoidable impurities, and Mn (%) / S (%) ≥ 40, T ≤ 1.38 [Mn / S] + 1115 , Mn: Mn content (wt%) S: S content (wt%) After heating at a heating temperature T (° C) that satisfies the content, finish temperature Ar ₃
After the transformation point, hot rolling at a coiling temperature of 600 ℃ or more and 720 ℃ or less, then pickling and cold rolling, then 625 ℃ or more 800 ℃
A method for manufacturing a non-oriented electrical steel sheet, which comprises annealing at the following temperature and then applying and baking an insulating film and the like.

(3) In weight%, C ≦ 0.0050%, 0.06% ≦ Si ≦ 1.0
%, 0.5% ≦ Mn ≦ 1.5%, 0.01% ≦ P ≦ 0.06%, 0.010%
≦ S ≦ 0.030%, 0.1% ≦ Al ≦ 0.5%, N ≦ 0.0050%, balance Fe and unavoidable impurities, and Mn (%) / S
(%) ≧ 40 steel, T ≦ 1.38 [Mn / S] +1115 However, Mn: Mn content (wt%) S: S content (wt%) at the heating temperature T (℃) After heating, finish temperature Ar ₃
After the transformation point, hot rolling at a coiling temperature of 600 ℃ or more and 720 ℃ or less, then pickling and cold rolling, then 625 ℃ or more 800 ℃
After being annealed at the following temperature to form a semi-processed steel sheet, after punching and shearing the steel sheet, the heating rate HR (° C / min) in the temperature range of 350 to 700 ° C is HR ≧ 60 [P] +1.4 However, P: a method for producing a non-oriented electrical steel sheet characterized by performing stress relief annealing so as to satisfy the P content (wt%) of the steel sheet.

(4) In weight%, C ≦ 0.0050%, 0.06% ≦ Si ≦ 1.0
%, 0.5% ≦ Mn ≦ 1.5%, 0.01% ≦ P ≦ 0.06%, 0.010%
≦ S ≦ 0.030%, 0.1% ≦ Al ≦ 0.5%, N ≦ 0.0050%, balance Fe and unavoidable impurities, and Mn (%) / S
(%) ≧ 40 steel, T ≦ 1.38 [Mn / S] +1115 However, Mn: Mn content (wt%) S: S content (wt%) at the heating temperature T (℃) After heating, finish temperature Ar ₃
After the transformation point, hot rolling at a coiling temperature of 600 ℃ or more and 720 ℃ or less, then pickling and cold rolling, then 625 ℃ or more 800 ℃
Annealing at the following temperature, then applying and baking an insulating film etc. to make a semi-processed steel sheet, punching and shearing the steel sheet, heating rate HR in the temperature range of 350 to 700 ° C
(° C / min) is HR ≧ 60 [P] +1.4, where P: P content (wt%) of the steel sheet is satisfied so that stress relief annealing is performed on the non-oriented electrical steel sheet. Production method.

[Action]

Hereinafter, the details of the present invention will be described together with the reasons for limitation.

First, the reasons for limiting the component composition in the present invention are as follows.

(1) P Content P is generally widely added as an element for increasing hardness and improving punchability without deteriorating magnetic properties in full-process materials and semi-process materials. Therefore, even in the full-process annealed material targeted by the present invention, when it is necessary to increase the conventional hardness and improve the punchability, a relatively large amount (0.
It is usually added around 1%). As described above, regarding the merits and demerits of P in the past, only the effect of increasing hardness and punching property has been clarified, and it can be said that there are currently no other technologies focusing on the merits and demerits of P. However, according to the present inventors' detailed examination of the merits and demerits of P in the full-process annealed material, although P certainly brings about an increase in hardness and an improvement in punching property, P does not affect the magnetic properties, especially the iron loss. There is an optimum value for the amount, and iron loss decreases through an increase in specific resistance only when P is controlled to an appropriate amount, and when P is added in excess of this appropriate amount (conventional P It has been found that when the alloy is added in this range), grain growth during strain relief annealing is hindered and the iron loss is increased. Therefore, in the present invention, the appropriate range of P is set as the requirement.

Moreover, as a result of further study, the P
The existence of the appropriate amount of p is peculiar to the full-process annealed material, and the existence of such an appropriate amount was not recognized in the case of the full-process material or the semi-processed material by double cold pressing. That is, as is well known, iron loss largely depends on the grain size, but in the full process material, since the microstructure is formed at a relatively small grain size during cold pressure-annealing, the driving force for grain growth is high. Moreover, since the annealing conditions (particularly the annealing temperature) exert an overwhelming influence on the grain size, it is considered that the influence of P does not become apparent. Also, in the case of a semi-processed material by double cold pressure, the influence of P does not become apparent because grain growth uses pressure-controlling strain as its driving force. On the other hand, in the case of the full process annealed material, the material that has once grown to a certain grain size by cold pressure-annealing is subjected to strain relief annealing by the customer again to further coarse grain growth. In addition to the fact that the driving force for grain growth is only the energy difference at the grain boundaries, the driving force itself is also small, and it is considered that the influence of P on the grain growth property becomes apparent. The mechanism of the effect of P on the grain growth property is not clear, but P is an element that tends to segregate at the grain boundaries.
Mobility of grain boundaries during grain growth due to lute-drag
It is thought that the essence is to reduce the.

Next, the merits and demerits of P will be clarified based on test examples, and the limit range and reason for the appropriate P amount will be described.

C: 0.0028%, Si: 0.31%, Mn: 0.81%, S: 0.018% (Mn /
S = 45), Al: 0.23%, N: 0.0019% and P content is 0.00
Steel with various changes from 2 to 0.088% (Group A), and C: 0.0043
%, Si: 0.80%, Mn: 1.31%, S: 0.024% (Mn / S = 55), A
L: 0.38%, N: 0.0035%, P content is 0.003-0.091%
And variously changed steel (Group B), the slab is
After hot-rolling, the product was hot-rolled at a finishing temperature of 820 ° C and a winding temperature of 670 ° C, then pickled and cold-rolled to a finishing thickness of 0.5 mm.
Annealed at ℃, then 750 ℃, which is equivalent to stress relief annealing at customers
It was subjected to annealing for 2 hours (heating rate 7 ° C / min). FIG. 1 shows the relationship between the P content, the iron loss (W _15/50 ) and the magnetic flux density (B ₅₀ ) of the test material thus obtained.

As is clear from the figure, in both the A group and the B group, only when the P amount is in the range of 0.01 to 0.06%, the A group has 4.4 W / k.
Good iron loss values around g and around 3.6 W / kg in Group B were obtained. On the other hand, if the amount of P is less than 0.01%, the amount of improvement in iron loss due to the increase in specific resistance is small, and therefore the amount of P is 0.
If the content exceeds 06%, the improvement in iron loss due to the increase in specific resistance exceeds the deterioration in grain growth, so the iron loss in both groups A and B is 0.6 W / kg or more higher than in the range of P: 0.01 to 0.06%. Has become. Thus, there is an appropriate range for the P amount, which is the A group,
0.01 regardless of group B, ie regardless of steel type
Since it is ˜0.06%, the amount of P is defined as 0.01˜0.06% in the present invention. As for B ₅₀ , when the amount of P is 0.06% or less, the decrease in B _{50 with} the increase of the amount of P is small, and the amount of P is 0.01 to 0.06.
It can also be seen that a good B ₅₀ can be obtained by setting it as%.

(2) Mn amount, S amount, Mn / s ratio By optimizing the P amount in the range of 0.01 to 0.06% as described above, the iron loss of the full process annealed material containing 0.1% or more of Al is significantly increased. Although improved, the object of the present invention is achieved, but more desirably, punchability should be improved. The reason for this is that P is an element that has the effect of improving punchability.
This is because the punchability is reduced accordingly. To solve the problem of punching property, Mn is used in the present invention.
The amount and S amount and the Mn / S ratio are optimized. That is, focusing on Mn S, which was conventionally avoided to impair the grain growth property, as long as it is coarsely precipitated, it was found from a series of studies that the punching property can be improved with almost no loss of grain growth. Was the second requirement of the present invention.

Hereinafter, appropriate values of the Mn amount, the S amount, and the Mn / S ratio and the reasons for limiting them will be described based on test examples.

C: 0.0031%, Si: 0.33%, P: 0.031%, Al: 0.25%, N:
Steel with various changes in Mn and S contents (C
Group)) and heating the slab to 1165 ° C, and then finishing temperature 81
Hot-rolled under conditions of 0 ℃ and coiling temperature of 700 ℃, 0.5mm after pickling
The cold-rolled sheet having a finish thickness of 1 was annealed at 720 ° C, and the burr height when the obtained annealed sheet was punched 200,000 times with a continuous punching machine was examined. Figure 2 shows the results of the test material M
It is organized by n and S amount. As is clear from the figure, the burr height ≤ 1 when S ≥ 0.010%, regardless of the amount of Mn.
It can be seen that a good punching property of 0 μm can be obtained. It is considered that this is because the amount of Mn S increases as the amount of S increases.

Fig. 3 shows the above-mentioned annealed sheet which is equivalent to the stress relief annealing in the consumer.
The iron loss (W _15/50 ) when subjected to annealing at 750 ° C. × 2 hr (heating rate 7 ° C./min) is arranged by Mn and S amounts. As is clear from the figure, Mn ≧ 0.5%, S ≦ 0.030%, Mn / S
It can be seen that good iron loss values of W _15/50 ≦ 4.7 W / kg are obtained when ≧ 40. It is considered that this is because Mn S coarsely precipitates in this region, and as a result, the grain growth property is hardly impaired. On the other hand, outside of this range, good iron loss values of W _15/50 > 5.2 W / kg have not been obtained, but this is the case for Mn / S <40.
Grain growth is deteriorated because Mn S does not precipitate coarsely, and when S> 0.030%, even if Mn / S ≧ 40 and Mn S precipitates coarsely, the absolute amount of Mn S itself is too large. Therefore, it is considered that the grain growth property deteriorated, and that the specific resistance was too small when Mn <0.5%, the iron loss increased. The magnetic flux density (B ₅₀ ) was around 1.75T in the above study range, and the influence of Mn and S was small.

As described above, from the results shown in FIGS. 2 and 3, Mn ≧ 0.5 in order to obtain a good punching property without impairing the grain growth property, that is, on the assumption that a good iron loss value is obtained.
%, 0.010% ≦ S ≦ 0.030%, and Mn / S ≧ 40. This is shown in FIG. In the figure, the upper limit of Mn is set to 1.5%, because the addition of Mn in excess of this has no advantage in magnetic characteristics and causes a cost increase.

The inventors of the present invention have conducted the above-described investigations on the amount of P within the range of 0.01 to 0.06% specified in the present invention, and other C,
For Si, Al, and N, the same was done for steels that were variously changed within the range shown in (3) below.
The same conclusions as in FIGS. 2 and 3 were obtained regarding punchability, iron loss, and magnetic flux density. Therefore, in the present invention, the amount of Mn, the amount of S,
As shown in FIG. 4, the Mn / S ratio is 0.5% ≦ Mn ≦ 1.5%, 0.01
It was defined as 0% ≦ S ≦ 0.030% and Mn / S ≧ 40.

(3) Other components C: If over 0.0050%, the magnetic properties deteriorate and there is a problem with magnetic aging, so an ultra-low carbon steel with an upper limit of 0.0050% is used.

Si: has the effect of increasing the specific resistance and decreasing the iron loss,
To obtain this effect sufficiently, it is necessary to add 0.06% or more. On the other hand, when the content exceeds 1.0%, the magnetic flux density decreases and the cost also increases, so the upper limit is 1.0.
%.

Like Al: Si, it is an element that lowers iron loss and should be positively added, but if it is less than 0.1%, fine Al N
And the grain growth property is impaired. In order to prevent this and obtain a good iron loss value, the lower limit is made 0.1%. However, if added in excess of 0.5%, the magnetic flux density will decrease and it will cause unnecessary cost increase, so the upper limit is made 0.5%.

If N: 0.0050% is exceeded, the magnetic properties will deteriorate, so 0.00
The upper limit is 50%.

 Next, the processing conditions will be described.

Based on the above-mentioned components, the third requirement of the present invention is to specify the processing conditions as described below. Even if the components are optimized, this can only show significant effects under certain processing conditions, and if the conditions are not met, the effects of component optimization will be significantly reduced. Is.

(1) Hot-rolling heating temperature If the hot-rolling heating temperature is excessively high, Al N and Mn S once coarsely precipitated in the slab stage are redissolved. In that case, a particular problem is re-dissolution of Mn S and subsequent fine re-precipitation. As described above, even if the amount of Mn S is relatively large, the punching property can be improved without impairing the grain growth property as long as it is coarsely precipitated. However, if Mn S is redissolved by the high temperature heating of the slab and then finely re-precipitated, the grain growth property is lowered and the iron loss is increased.

On the other hand, with respect to Al N, since the steel of the present invention has Al ≧ 0.1%, even if re-melting of Al N occurs, coarse precipitation occurs again thereafter, and thus no special consideration is required.

As described above, the heating temperature during hot rolling has its upper limit from the viewpoint of preventing Mn S from being redissolved, but as a result of further studies by the present inventors, this upper limit temperature depends on the Mn S ratio. I found out. That is, when the Mn / S ratio is large, even if Mn S is re-dissolved to some extent, it is likely to coarsen again when re-precipitating (because few Mn S remain as fine Mn S). Is acceptable. On the other hand, when the Mn / S ratio is small, the hot rolling heating temperature needs to be low for the opposite reason. Based on this consideration, the present inventors conducted the following experiments and studies to determine the upper limit of the hot rolling heating temperature.

C: 0.0031%, Si: 0.33%, P: 0.031%, Al: 0.25%, N:
Steel with a constant M of 0.0023% and Sn of 0.013%, with various changes of Mn in the range of 0.5 to 1.5% (D-1 group), and also S: 0.01.
Steel with various changes of Mn in the range of 0.5-1.5% under 6% (D
-2 group), and also with S: 0.029%, Mn 0.5-1.5
% Of steel (D-3 group) was used, after heating the slab to various temperatures, the finishing temperature was 810 ° C and the coiling temperature was 7
Hot-rolled at 00 ℃, pickled, and then cold-rolled to a finish thickness of 0.5mm, annealed at 720 ℃, and subsequently 750 ℃ × 2hr (heating rate 7 (° C / min).

Fig. 5 shows the iron loss (W
_15/50 ) is arranged by Mn / S ratio and hot rolling heating temperature T (° C). From the figure, in the steel of the present invention satisfying Mn / S ≧ 40, regardless of the Mn amount and the S amount, the heating temperature T
The upper limit of (℃) is expressed as a function of the Mn / S ratio of T = 1.38 [Mn / S] +1115, and when the heating temperature is below this, W _15/50 ≦ 4.7 W / kg and good iron loss It turns out that the value is obtained. On the other hand, when the heating temperature exceeds the upper limit,
Insufficient coarsening during re-dissolution of Mn S and subsequent re-precipitation, namely Mn
Due to the fine precipitation of S, the grain growth during strain relief annealing deteriorates, and the iron loss increases to W _15/50 > 5.2 W / kg. Also, Mn / S <
When it deviates from the range of the present invention to 40, it can be confirmed that a good iron loss value cannot be obtained even if extremely low temperature heating of about 1000 ° C. is performed. Regarding the magnetic flux density (B ₅₀ ), all were around 1.75 T in the above study range, and the influence of the hot rolling heating temperature was small.

Based on the above results, in the present invention, the heating temperature T (° C.) in hot rolling is defined as T ≦ 1.38 [Mn / S] +1115.

(2) Hot rolling finishing temperature When the hot rolling is finished at the Ar ₃ transformation point or higher, the magnetic properties, particularly the magnetic flux density is significantly lowered, so the finishing temperature is set to the Ar ₃ transformation point or lower.

(3) Hot rolling coiling temperature Using the steel D-1 group (S = 0.013%) and steel D-3 group (S = 0.029%) used in FIG.
After heating, the finishing temperature was kept constant at 810 ° C, the rolling temperature was variously changed, and the hot-rolled product was pickled, cold-rolled to a thickness of 0.5 mm, then annealed at 720 ° C, and continuously used by customers. The sample was subjected to annealing at 750 ° C. × 2 hr (heating rate 7 ° C./min), which is equivalent to the strain relief annealing of. FIG. 6 shows the iron loss (W _15/50 ), magnetic flux density (B ₅₀ ) and surface roughness Ra of the test material obtained in this way as Mn
It is arranged by the / S ratio and the winding temperature.

From the figure, in the steel of the present invention satisfying Mn / S ≧ 40, Mn
W _15/50 ≤ 4.7W / kg, B ₅₀ 1.75T, surface roughness only when the winding temperature is 600 to 720 ℃, regardless of the amount and S amount.
It can be seen that excellent magnetic properties and surface properties of Ra <0.4 μm can be obtained. On the other hand, even in the steel satisfying the composition conditions of the present invention with Mn / S ≧ 40, when the coiling temperature is 590 ° C., the progress of recrystallization of the hot rolled sheet, coarsening and Al N, Mn S
Is not sufficiently coarsened, and both iron loss and magnetic flux density are significantly deteriorated. On the other hand, if the coiling temperature is too high at 730 ° C, there is no problem in terms of magnetic properties, but an internal oxide layer with difficulty in pickling develops during coiling, and grain boundary oxidation is remarkable, which causes pickling. Grain boundary erosion occurs at this time, and microcracks frequently occur from this point at cold pressure, resulting in a large deterioration of surface properties such as Ra> 0.7 μm. Further, in steels having Mn / S <40 which deviates from the scope of the present invention, W _15/50 > 5.0 W / kg is obtained at any winding temperature, and it is also understood that good iron loss cannot be obtained.

From the above results, in the present invention, the winding temperature in hot rolling is defined as 600 ° C or higher and 720 ° C or lower.

(4) Pickling and cold rolling It is not necessary to specify, and it can be carried out by a conventional method.

(5) Annealing temperature after cold pressing If this annealing temperature exceeds 800 ° C, the grain size becomes coarse,
(111) grains, which are not desirable in terms of magnetic properties, develop and the magnetic flux density decreases. In addition, the softening is remarkable, and defective products are likely to occur during punching or stacking and caulking of punched products due to the winding of the coil, so the upper limit is set to 800 ° C.
On the other hand, since the iron loss after stress relief annealing in the consumer hardly depends on the main annealing temperature after cold pressing, there is no lower limit of the annealing temperature in this sense, but when performing low temperature annealing below 625 ° C. Causes remarkable deterioration of punchability. That is, the die is heavily worn due to punching of a significantly hard material, and the increase in the burr height during continuous punching is accelerated. Therefore, the lower limit of the annealing temperature needs to be 625 ° C.

(6) Annealing condition after punching / shearing After the above-mentioned annealing, the steel sheet is coated with an insulating film, etc., if necessary, to be a final product as a full-process annealed material, and then punching / shearing. And further subjected to stress relief annealing. This punching / shearing and strain relief annealing are usually performed by customers.

Here, in the full-process annealed material manufactured under the conditions as described above, the heating rate at the time of stress relief annealing is important in order to obtain the desired magnetic properties, and the manufacturing method of the steel sheet including stress relief annealing is included. Considering this, it is necessary to specify the heating rate during stress relief annealing. This is because, as described above, during strain relief annealing, mobility of grain boundaries is reduced by solute-drag due to segregation of P in grain boundaries, and grain growth property is deteriorated. As its characteristic, even if the P content is reduced in this way, if the heating rate during stress relief annealing is inappropriately slow, grain boundary migration and P grain boundary segregation compete, or the latter The grain boundary causes P segregation, and the grain boundary must move while solute-draging the segregated P.
As a result, the grain boundary mobility is lowered, that is, the grain growth property is deteriorated. Therefore, with respect to the heating rate at the time of strain relief annealing, there is a lower limit value according to the ease of segregation, that is, the P amount. Further, since the problem here is the grain boundary segregation of P, the lower limit of the heating rate should be considered in the range of 350 to 700 ° C. where the grain boundary segregation is active.

Hereinafter, the lower limit of the heating rate and the reason for the limitation will be described based on test examples.

Using the above-mentioned steel group A and group B, the slab was heated to 1130 ° C, then hot-rolled at a finishing temperature of 840 ° C and a winding temperature of 700 ° C, and after pickling, cold-rolled to a finishing thickness of 0.5 mm. Next, it was annealed at 700 ° C, and subsequently annealed at 750 ° C for 2 hours, which is equivalent to the strain relief annealing at consumers, was performed at various heating rates at 350 to 700 ° C. FIG. 7 shows the iron loss (W _15/50 ) of the test material thus obtained, arranged by P amount and heating rate HR (° C./min) at 350 to 700 ° C.

From the figure, in the steel of the present invention satisfying 0.01 ≤ P ≤ 0.06%, both A group and B group, that is, regardless of the steel type,
The lower limit of the heating rate HR is a function of the amount of P of HR = 60 [P] + 1.4, and when the heating rate is higher than this, W _15/50 <4.6 W / kg in group A, W in group B _It can be seen that a good iron loss value of _15/50 <3.7 W / kg is obtained. On the other hand, even if
Even in the steel satisfying the composition of the present invention of 0.01 ≦ P ≦ 0.06%, if the heating rate is lower than the lower limit defined by the above formula, grain growth during stress relief annealing due to grain boundary segregation of P occurs. As a result, the iron loss of both the group A and the group B is increased by 0.3 W / kg or more. It can also be confirmed that in steels with P <0.01% or P> 0.06%, which deviates from the scope of the present invention, good iron loss cannot be obtained at any heating rate. The effect of the heating rate on the magnetic flux density (B ₅₀ ) was small.

From the above results, in the present invention, the heating rate HR during strain relief annealing
(° C / min) is defined as HR ≧ 60 [P] +1.4. on the other hand,
The upper limit does not have to be specified in terms of magnetic properties, but when the heating rate is unduly increased, the temperature distribution becomes uneven and the steel sheet is deformed. Therefore, the upper limit of the heating rate is the specification of the strain relief annealing furnace for each consumer,
It is necessary to decide it in consideration of the quantity of 1 lot of annealing.

Regarding the stress relief annealing temperature and time, since the grain boundary segregation of P can be avoided by optimizing the heating rate as described above, no special consideration is required, and 720 to 800 ° C as usual,
The condition may be about 1 to 2 hours.

〔Example〕

The slabs of the steel components shown in Table 1 are shown in Tables 2-a to 2-c.
Hot-rolled under the hot-rolling conditions shown in the table, and after pickling this finish thickness of 0.
After cold rolling to 5 mm, it was subsequently annealed at the annealing temperature shown in the same table for 3 minutes. The thus-obtained annealed plate was subjected to a continuous punching test of 200,000 times under the conditions shown in the upper part of FIG. 2 and the burr height at the time of punching 200,000 times was measured.
In addition, the above-mentioned annealed plate is 750 ° C x 2 which is equivalent to the strain relief annealing at the consumer.
After being subjected to hr annealing, magnetic properties were evaluated by an Epstein test based on JIS method. The results of these measurements are
It is also shown in Tables a to 2-c.

In these examples, Table 2-a shows the influence of the component conditions, Table 2-b shows the influence of the hot rolling-annealing conditions,
Table 2-c shows the effects of heating rate during stress relief annealing.

As is clear from Tables 2-a to 2-c, those obtained by the method of the present invention have good magnetic properties (iron loss: W _15/50 and magnetic flux density: B ₅₀ ) and punchability (barrier height ≤ 10 μm) has been obtained. On the other hand, in the comparative method (one of the components and manufacturing conditions is out of the range of the present invention), the iron loss, the magnetic flux density, and the punchability are inferior (iron loss: W
_15/50 is higher than the method of the present invention by 0.5 W / kg or more, and the magnetic flux density: B
₅₀ is 0.02 T or more lower than that of the method of the present invention, and the burr height is 25 μm or more.) From this, the effects and usefulness of the present invention can be clearly understood.

[Effects of the Invention] According to the present invention described above, a full-strength non-oriented electrical steel sheet excellent in magnetic properties and punchability can be easily obtained without incurring a cost increase due to addition of a special alloy element or addition of a process. Process annealed material and punching / shearing-strain relief annealed material using the material can be manufactured. The improvement of magnetic properties, especially the reduction of iron loss, meets the demand for energy saving which is a social need, and the improvement of punchability is
This increases the number of times continuous punching is possible without die polishing and contributes to improvement in productivity.

[Brief description of drawings]

FIG. 1 is a graph showing the influence of the amount of P on iron loss and magnetic flux density and its appropriate range. FIG. 2 is a graph showing the influence of the amount of Mn and S on the punchability and its appropriate range. FIG. 3 is a graph showing the influence of Mn, the amount of S, and the Mn / S ratio on iron loss and its appropriate range. Figure 4 shows Mn,
It is a graph which shows the range of the present invention regarding S amount and Mn / S ratio. FIG. 5 is a graph showing the influence of hot rolling heating temperature and Mn / S ratio on iron loss and its appropriate range. Figure 6 shows
Hot rolling temperature for iron loss, magnetic flux density, surface roughness and
6 is a graph showing the influence of the Mn / S ratio and its appropriate range. Seventh
The figure is a graph showing the influence of the heating rate and the amount of P during stress relief annealing on iron loss and its appropriate range.

Claims (4)

[Claims] 1. A method for producing a semi-processed non-oriented electrical steel sheet, wherein stress relief annealing is performed after punching and shearing,
% By weight, C ≦ 0.0050%, 0.06% ≦ Si ≦ 1.0%, 0.5% ≦
Mn ≦ 1.5%, 0.01% ≦ P ≦ 0.06%, 0.010% ≦ S ≦ 0.030
%, 0.1% ≤ Al ≤ 0.5%, N ≤ 0.0050%, balance Fe and unavoidable impurities, and steel satisfying Mn (%) / S (%) ≥ 40, T ≤ 1.38 [Mn / S] +1115 However, after heating at a heating temperature T (° C) that satisfies the Mn: Mn content (wt%) S: S content (wt%), the finishing temperature Ar ₃
After the transformation point, hot rolling at a coiling temperature of 600 ℃ or more and 720 ℃ or less, then pickling and cold rolling, then 625 ℃ or more 800 ℃
A method for manufacturing a non-oriented electrical steel sheet, which comprises annealing at the following temperature. 2. A method for manufacturing a semi-process non-oriented electrical steel sheet, which is subjected to stress relief annealing after punching / shearing,
% By weight, C ≦ 0.0050%, 0.06% ≦ Si ≦ 1.0%, 0.5% ≦
Mn ≦ 1.5%, 0.01% ≦ P ≦ 0.06%, 0.010% ≦ S ≦ 0.030
%, 0.1% ≤ Al ≤ 0.5%, N ≤ 0.0050%, balance Fe and unavoidable impurities, and steel satisfying Mn (%) / S (%) ≥ 40, T ≤ 1.38 [Mn / S] +1115 However, after heating at a heating temperature T (° C) that satisfies the Mn: Mn content (wt%) S: S content (wt%), the finishing temperature Ar ₃
After the transformation point, hot rolling at a coiling temperature of 600 ℃ or more and 720 ℃ or less, then pickling and cold rolling, then 625 ℃ or more 800 ℃
A method for manufacturing a non-oriented electrical steel sheet, which comprises annealing at the following temperature and then applying and baking an insulating film and the like. 3. In weight%, C ≦ 0.0050%, 0.06% ≦ Si ≦ 1.
0%, 0.5% ≤ Mn ≤ 1.5%, 0.01% ≤ P ≤ 0.06%, 0.010%
≦ S ≦ 0.030%, 0.1% ≦ Al ≦ 0.5%, N ≦ 0.0050%, balance Fe and unavoidable impurities, and Mn (%) / S
(%) ≧ 40 steel, T ≦ 1.38 [Mn / S] +1115 However, Mn: Mn content (wt%) S: S content (wt%) at the heating temperature T (℃) After heating, finish temperature Ar ₃
After the transformation point, hot rolling at a coiling temperature of 600 ℃ or more and 720 ℃ or less, then pickling and cold rolling, then 625 ℃ or more 800 ℃
After being annealed at the following temperature to form a semi-processed steel sheet, after punching and shearing the steel sheet, the heating rate HR (° C / min) in the temperature range of 350 to 700 ° C is HR ≧ 60 [P] +1.4 However, P: a method for producing a non-oriented electrical steel sheet characterized by performing stress relief annealing so as to satisfy the P content (wt%) of the steel sheet. 4. By weight%, C ≦ 0.0050%, 0.06% ≦ Si ≦ 1.
0%, 0.5% ≤ Mn ≤ 1.5%, 0.01% ≤ P ≤ 0.06%, 0.010%
≦ S ≦ 0.030%, 0.1% ≦ Al ≦ 0.5%, N ≦ 0.0050%, balance Fe and unavoidable impurities, and Mn (%) / S
(%) ≧ 40 steel, T ≦ 1.38 [Mn / S] +1115 However, Mn: Mn content (wt%) S: S content (wt%) at the heating temperature T (℃) After heating, finish temperature Ar ₃
After the transformation point, hot rolling at a coiling temperature of 600 ℃ or more and 720 ℃ or less, then pickling and cold rolling, then 625 ℃ or more 800 ℃
Annealing at the following temperature, then applying and baking an insulating film etc. to make a semi-processed steel sheet, punching and shearing the steel sheet, heating rate HR in the temperature range of 350 to 700 ° C
(° C / min) is HR ≧ 60 [P] +1.4, where P: P content (wt%) of the steel sheet is satisfied so that stress relief annealing is performed on the non-oriented electrical steel sheet. Production method.