JP4269138B2 - Non-oriented electrical steel sheet for semi-process - Google Patents

Description

【００６４】
【表２】

【００６５】
〔実施例２〕
転炉にて精錬し真空処理後連続鋳造して得た、厚さ230mmの表３に示す化学組成の鋼片を用い、加熱温度1140℃として熱間圧延をおこない厚さ2.3mmの熱延鋼板とした。熱延鋼板は水素雰囲気中にて800℃、10時間の焼鈍をおこなった後、冷間圧延して0.5mm厚とし、連続処理ラインにて仕上げ焼鈍を施し表面に絶縁皮膜を塗布した。このようにして得られた鋼板について、表面硬さおよび結晶粒径を測定した。これらの鋼板から幅30mm、長さ280mmの試験片を長さ方向が圧延方向または幅方向となるようにして二方向で採取し、窒素雰囲気中にて750℃、2時間の歪取り焼鈍をおこなった。歪取り焼鈍後の試験片はJIS-C-2550に準じてエプスタイン枠を用い鉄損Ｗ_{１５／５０}および磁束密度Ｂ_５０を測定した。またこれらの試験片については、平均結晶粒径および1／4厚さ位置における｛222｝面積分強度も測定した。上述の各特性の測定結果を表４に示す。
【００６６】
【表３】

【００６７】
【表４】

【００６８】
表３にて鋼番号ＭおよびＮは、化学成分が本発明で定める範囲に入っているが、他の番号の鋼はいずれも本発明範囲外である。これら二種の鋼から製造された電磁鋼板は、表４の特性測定結果の試験番号13および14と他の試験結果との比較からあきらかなように、歪取り焼鈍後の鉄損が低く、かつ磁束密度が高い結果を示している。また、｛222｝面積分強度も他の鋼の場合に比し低い値となっている。
【００６９】
〔実施例３〕
表３にて、ＭおよびＮとして示した化学組成の鋼片を用い、熱間圧延の加熱温度、熱延板の焼鈍条件、および冷間圧延後の仕上げ焼鈍温度を変え、得られた鋼板について、表面硬さおよび結晶粒径を測定し、さらに試験片を切り出して歪取り焼鈍のおこなった後、磁気特性および｛222｝面積分強度を測定した。これら鋼板の特性測定方法はいずれも実施例２と同じである。この場合、内径510mm幅80mmのスリットコイルの内径近くから長さ300mmを切り出し、定盤上においてそのそり高さを測定することにより、巻き癖の発生を調査した。これらの処理条件、および特性測定結果を合わせて表５に示す。
【００７０】
【表５】

【００７１】
鋼番号ＭおよびＮは、化学組成がいずれも本発明で規定する範囲内である。このため、表５の結果では、歪取り焼鈍後の磁気特性はほとんどの場合、Ｗ_{１５／５０}が3.0W／kg以下、Ｂ_５０が1.70以上という当初の目標値が達成されている。そして、試験番号21、23、28および30の結果と、試験番号19、20、22、24、25、26、27、29、31および32の結果との対比から、本発明の組成範囲を有する鋼にて、鋼板製造工程の諸条件を限定することにより、さらに一層すぐれた歪取り焼鈍後磁気特性を有するセミプロセス無方向性電磁鋼板の得られることがわかる。
【００７２】
ただし、仕上げ焼鈍の温度が低すぎる試験番号24および31では、結晶粒が小さく硬さの高い鋼板となっており、仕上げ焼鈍温度が高すぎる試験番号25および32では、結晶粒が大きくなりすぎて、コイルに巻き癖が残って切り出し試験片にそりが生じている。
【００７３】
【発明の効果】
本発明のセミプロセス無方向性電磁鋼板は、打抜き性に好ましい硬さを有し、歪取り焼鈍後の磁気特性がすぐれている。したがって、小形のモータや変圧器など電気機器用の鉄心として、とくに歪取り焼鈍して使用する場合に、低損失かつ高効率な機器とすることができ、省エネルギーなど産業へ寄与が大きい。
【図面の簡単な説明】
【図１】歪取り焼鈍後の鉄損Ｗ_{１５／５０}におよぼす、Ｍｎ量が異なる場合のＰ含有量の影響を示す図である。
【図２】歪取り焼鈍後の磁束密度Ｂ_５０におよぼす、Ｍｎ量が異なる場合のＰ含有量の影響を示す図である。[0001]
[Technical field to which the invention belongs]
The present invention relates to a non-oriented electrical steel sheet that is applied to a core material of an electrical device such as a motor and is used after performing post-molding distortion removal annealing such as punching, that is, a semi-processed non-oriented electrical steel sheet.
[0002]
[Prior art]
From the viewpoint of global warming prevention and energy saving, various types of electrical equipment are being made more efficient. Iron core electrical steel sheets used in rotating machines and transformers are also low in cost and low in iron. It is required to have excellent magnetic properties such as loss and high magnetic flux density.
[0003]
Non-oriented electrical steel sheets are mainly used for small motors and small transformers, but for these small electrical devices, in addition to the above-mentioned low iron loss and high magnetic flux density, punchability It is also required to be excellent.
[0004]
As a means for reducing the iron loss value of the non-oriented electrical steel sheet, it is known that a method of increasing the crystal grain size by increasing the contents of Si, Al and Mn is known. However, an increase in the content of Si, Al or Mn decreases the magnetic flux density, and further, an increase in the content of these elements hardens the steel, leading to a deterioration in punchability, that is, an increase in tool wear during continuous punching. In addition, the larger crystal grains compared to the complicated core shape of a small motor is one of the factors that increase flashing and burr and deteriorate the processing accuracy of punched products.
[0005]
In this way, the means that can be taken to improve the characteristics of non-oriented electrical steel sheets are that other required characteristics often deteriorate if attention is focused on one characteristic, and the steel sheet maker is a consumer. The production of electrical steel sheets with better performance is being promoted from the balance between the characteristics desired by the company and the production costs.
[0006]
Conventionally, in the United States, mild rolling distortion has been added to the small motor core in the United States, assuming that it will be annealed by the customer after punching, and the grains become coarse due to the annealing by the customer. Many electrical steel sheets, which are said to be semi-processed materials, have been used. On the other hand, a material that is sufficiently annealed on the steel manufacturer side to have the required electromagnetic characteristics and that can be used without annealing by the customer is called a full process material.
[0007]
In Japan, non-oriented electrical steel sheets mainly for small motors have often taken the form of full process materials. However, it has been known on the side of customers such as small motor manufacturers that motor performance is greatly improved by performing strain relief annealing after punching into the required shape such as a motor core even with this full process material. . As the demand for higher performance of motors increases, it is common to incorporate this strain relief annealing process into the production line.
[0008]
When a processing method such as a semi-process material that performs strain relief annealing is widely adopted by customers, naturally, products corresponding to this will be desired. Steel manufacturers usually manufacture electrical steel sheets with the goal of having good characteristics at the time of shipment, but semi-processed materials are good after strain relief annealing even if their magnetic properties are poor at the time of shipment. The premise is that characteristics can be obtained.
[0009]
For this reason, it is desired that the grain growth easily occurs at the time of strain relief annealing, and that the texture formed at that time is more favorable for the magnetic properties of the non-oriented electrical steel sheet. In the case of a full-process material, it is desirable to increase the crystal grains in order to ensure the magnetic properties, and it tends to be a soft steel plate. When the hardness is lowered, the punchability is deteriorated due to the deterioration of dimensional accuracy due to an increase in burr and drool. Therefore, it is necessary to contain a component for maintaining the hardness. However, even if the semi-processed material is softened after strain relief annealing, this is not an object of necessary characteristics, so that there is an advantage that the component limitation considering punchability is relaxed.
[0010]
As a measure to improve the magnetic properties of non-oriented electrical steel sheets, it is generally based on ultra-low carbon steel with C of 0.01% or less, such as S and O that cause the formation of non-metallic inclusions that deteriorate the magnetic properties. Steel with a composition that appropriately contains elements that increase the electrical resistance of Si and Al, improve the magnetic properties, and increase the hardness appropriately is used as much as possible, and the manufacturing process is after hot rolling. The means of performing hot-rolled sheet annealing before cold rolling is employed.
[0011]
For semi-process type non-oriented electrical steel sheets, in addition to the composition and manufacturing method, several inventions with further improvements have been proposed, especially on the premise of being subjected to strain relief annealing after punching. For example, JP-A-8-3699 discloses a strain relief annealing in which Si is 1.0% or less, Al is 0.2 to 1.5%, Ti is 15 ppm or less, Zr is reduced to 80 ppm or less, and REM is contained in 2 to 80 ppm. A later non-oriented electrical steel sheet invention with excellent iron loss was disclosed, and JP-A-8-325678 discloses a steel sheet having a similar composition containing REM, except that Si is 1.0 to 2.5%. It is disclosed.
[0012]
In addition, the invention disclosed in Japanese Patent Laid-Open No. 11-158589 particularly limits the amount of impurity Ti within a range of 0.0015 to 0.0050%, and suppresses variations in magnetic properties after strain relief annealing. Kai 2001-294997 discloses an invention of a non-oriented electrical steel sheet in which the total content of Si and Al is in the range of 1.6 to 2.7%, and the magnetic flux density is improved after strain relief annealing. Yes.
[0013]
In these inventions, all steel sheets subjected to sufficient annealing during the cold rolling after hot rolling or during the cold rolling after hot rolling are processed by punching or the like. When it is subjected to stress relief annealing later, good magnetic properties are obtained.
[0014]
As described above, various developments have been made on semi-processed non-oriented electrical steel sheets on the premise of strain relief annealing by customers, but it has excellent punching workability, which is a characteristic of semi-process materials, and after strain relief annealing. In particular, it is difficult to say that a sufficiently satisfactory steel sheet has been obtained from the viewpoint that good magnetic properties are obtained and that it can be reasonably manufactured.
[0015]
[Problems to be solved by the invention]
  The object of the present invention is a semi-processed non-oriented electrical steel sheet that has excellent punching properties and exhibits excellent magnetic properties when subjected to strain relief annealing.And manufacturing method thereofIs in the provision of.
[0016]
[Means for Solving the Problems]
The present inventors have made various studies in order to improve the performance of semi-processed non-oriented electrical steel sheets that are subjected to strain relief annealing by customers. Strain relief annealing is currently adopted by customers as a standard condition of soaking for 1 to 2 hours at 750 ° C after punching, and excellent magnetic properties are obtained when this annealing is performed. Must be. However, since punching is performed before strain relief annealing, it goes without saying that a surface insulation coating is applied to improve punchability when shipped from the factory, but the dimensional accuracy of the punched product is good. In order to reduce tool wear, the hardness needs to be in an appropriate range.
[0017]
Usually, Si, Al, Mn, P and the like are added to the non-oriented electrical steel sheet. Therefore, in order to reconfirm the effects of these main elements, steels with various contents were melted, magnetic steel sheet samples were prepared, and their effects on hardness and magnetic properties after strain relief annealing were investigated. did.
[0018]
The strain relief annealing that soaks at 750 ° C for 1 to 2 hours is a condition that allows the crystal grains to grow sufficiently, and the magnetic properties of non-oriented electrical steel sheets generally become better as the crystal grains become larger. . Therefore, in the melting of these steels, the content of impurity elements such as C, S, N, O, and Ti that form precipitates and inclusions that inhibit crystal grain growth was made as low as possible.
[0019]
Preparation of the steel plate sample was performed by hot rolling after heating the material to 1140 ° C, and the obtained hot-rolled steel plate was annealed at 800 ° C for 10 hours and then cold-rolled at a rolling rate of 78% to a thickness of 0.5 mm. . The steel sheet after cold rolling was finish-annealed at 800 ° C. for 30 seconds. This corresponds to the factory shipment state, but in an actual product, the surface is coated with an insulating film. About the steel plate after finish annealing, the hardness and the crystal grain size were measured.
[0020]
A 30mm wide, 100mm long test piece is punched from the steel sheet that has been annealed, annealed at 750 ° C for 2 hours, and then subjected to iron loss W using a small single plate magnetic measuring instrument._15/50And magnetic flux density B₅₀Was measured, and the crystal grain size was examined in the cross section. The magnetic properties were measured by collecting two types of test pieces whose length directions were parallel and perpendicular to the rolling, and the average value was obtained.
[0021]
From the measurement results obtained in this way, the effects of the contents of the main elements are summarized, and several effects have become apparent. First, Si is effective in lowering iron loss, but it greatly affects the hardness after finish annealing, so a large amount cannot be contained. Al decreases the iron loss like Si, but if it is contained in a large amount, the magnetic flux density decreases. Mn has the same effect as Al, but the effect is not as great as that of Al. From this tendency, the content limit range of each element is roughly determined.
[0022]
  When we investigate the effects of these three elements together,
Si (%) + 0.5Mn (%) + Al (%) ・ ・ ・ ・ ・ ・(3)
It was found that there is a good correlation with the iron loss and magnetic flux density after strain relief annealing.
[0023]
  the above(3)As the value of the equation increases, the iron loss decreases, and the magnetic flux density also decreases. Therefore, once the target upper limit of iron loss and the target lower limit of magnetic flux density are determined,(3)The upper and lower limits of the formula can be set. This equation has a good correlation with the electrical resistance of steel, and increasing the electrical resistance reduces the eddy current loss of the steel sheet and lowers the iron loss value, while increasing the content of these elements per unit volume It is presumed that the magnetic flux density will decrease as the amount of Fe decreases.
[0024]
  However, when examining the iron loss and magnetic flux density of the steel samples of each composition,(3)It turns out that there are many things that cannot be organized by the formula alone. In particular, the influence of the Mn content is(3)Sometimes it can be organized in relation to formulas, but sometimes it is not. Then, as a result of further examination about the influence of Mn, the following has become apparent.
[0025]
  When the amount of Mn is changed to improve magnetic properties such as iron loss, too much addition is not preferable. When I examine the limits,
    Mn (%) ≤ Si (%) + 2Al (%) -0.5(2)
It was found that it was necessary to be satisfied. That is, the increase in the Mn content cannot be achieved unless Si or Al is contained to some extent. Mn amount is this(2)If the value does not satisfy the expression,(3)The relationship between the iron loss and magnetic flux density arranged in the formula and the component content is not established, and only the performance that is significantly lower than the expected magnetic characteristics can be obtained. Ie(3)Electrical steel sheet with desired magnetic properties using the formulaTheIt becomes impossible to select components for obtaining.
[0026]
  this(2)The condition shown by the equation seems to be mainly related to the crystal grain growth during the stress relief annealing, and the Mn content is(2)If the value of the formula is not satisfied, the crystal grains are difficult to increase. Si and Al are ferrite phase forming elements, while Mn is an austenite phase forming element. For this reason, in the process of hot rolling and hot-rolled sheet annealing, it affects the dispersion state of fine precipitates that hinder grain growth by lowering the transformation temperature, and this affects the grain growth during strain relief annealing. I thought it was.
[0027]
  In order to improve the magnetic properties of the non-oriented electrical steel sheet, increasing the electrical resistance as described above is effective in improving the iron loss, and ensuring that the alloy components are not increased more than necessary is effective in securing the magnetic flux density. Increasing the crystal grain size is effective for reducing iron loss because it reduces hysteresis loss due to magnetization. Inappropriate amount of Mn(2)If the equation is not satisfied, it has been estimated that the growth of crystal grains is insufficient. However, the fact that the crystal grains do not increase does not improve the magnetic characteristics in this way.
[0028]
Further, it has been found that Mn has an interaction with P, and when the amount of P increases, the effect of reducing iron loss by increasing the amount of Mn decreases. In addition, if the amount of P is high, the magnetic flux density decreases due to an increase in Mn, but if the amount of P is decreased, a tendency that the magnetic flux density increases due to an increase in Mn has also been found. Therefore, when increasing the Mn content to improve magnetic properties such as lowering iron loss, it is better to reduce the P content as much as possible.
[0029]
In the case of a full process non-oriented electrical steel sheet, a small amount of P increases the hardness of the steel sheet and has little influence on the magnetic properties, so it is preferably added to improve punchability. On the other hand, in semi-processed non-oriented electrical steel sheets, punching is performed before strain relief annealing, so it can be hardened by controlling the finish annealing conditions to reduce crystal grain size or introducing strain. It is not necessary to add much P.
[0030]
To improve the magnetic properties of non-oriented electrical steel sheets, increasing the electrical resistance without increasing the alloy elements as much as possible and increasing the crystal grain size are effective in improving iron loss. In addition, when the preferred orientation of the crystals constituting the steel sheet, that is, the texture is in a state favorable for magnetization, iron loss can be reduced by reducing hysteresis loss, and magnetic flux density can be improved.
[0031]
When examining the X-ray diffraction integrated intensity for the {222} crystal orientation parallel to the plate surface in the steel plate samples after strain relief annealing with different Mn content and P content, the Mn content is small and the P content is low. When the amount is large, the integral strength of the {222} plane is strong, and when the amount of Mn is large and the amount of P is small, the strength is weak. The strong integrated strength of the {222} plane parallel to the plate surface as a texture means that the <100> axis, which is the easy magnetization orientation of iron crystals, is small in the plate surface direction where the steel plate is magnetized. This is considered to have resulted in inferior magnetization characteristics. The reason why the presence of Mn and P affects the texture in this way is not well understood, but it is clear that the magnetic properties after strain relief annealing can be improved by controlling the amount of Mn and the amount of P. It is.
[0032]
Regarding the composition of the steel, the range was selected as described above, and various studies were also conducted on preferable manufacturing conditions for making the steel ingot a semi-processed non-oriented electrical steel sheet. First, it is necessary to make the steel slab heating temperature during hot rolling as low as possible in order to promote crystal grain growth during strain relief annealing. However, if the temperature is too low, the hot rolling process becomes difficult, and the crystal grains may not grow sufficiently during annealing of the hot-rolled sheet, so the heating temperature range is limited.
[0033]
Annealing of a hot-rolled sheet after hot rolling, which is generally used in the manufacture of non-oriented electrical steel sheets, improves the magnetic properties even in this semi-processed non-oriented electrical steel sheet. This is because by increasing the crystal grains of the steel sheet before cold rolling, a texture favorable to the magnetic properties of the steel sheet is formed by annealing after cold rolling. Further, it is considered that there is an effect of changing the distribution and form of fine precipitates so as not to inhibit the crystal grain growth during the strain relief annealing.
[0034]
In the case of a full-process non-oriented electrical steel sheet, the finish annealing after the cold rolling needs to be sufficiently annealed to take up the processing distortion of the rolling and enlarge the crystal grains. However, since the semi-processed non-oriented electrical steel sheet is subjected to strain relief annealing later, the hardness should be suitable for punching, so that the crystal grains are of an appropriate size that facilitates grain growth during strain relief annealing. Keep the annealing temperature low.
[0035]
Based on the above examination results, it is in the range of Vickers hardness HV125 to 145, which is a region showing good punchability as a semi-processed electrical steel sheet product, and after 750 ° C, 2 hours of strain relief annealing With a goal of magnetic properties of a core thickness of 0.5 mm or less and an iron loss of 3.0 W / kg or less and a magnetic flux density of 1.70 or more, the component range and manufacturing method limit conditions were further investigated. The present invention is based on the results of such studies, and the gist thereof is as follows.
[0036]
  (1) In mass%, C: 0.005% or less, Si: 0.4 to 1.7%, Mn: 0.65 to 1.5%, sol. Al: 0.3 to 2.3%, P:0.02 %Hereinafter, S: 0.004% or less, Ti: 0.002% or less, N: 0.005% or less, the balance is Fe and impurities, and the contents of Si, Mn and Al are as follows.(1)and(2)A semi-processed non-oriented electrical steel sheet satisfying the formula and having an average crystal grain size of 10 to 35 μm.
[0037]
    2 ≦ Si (%) + 0.5Mn (%) + Al (%) ≦ 3(1)
    Mn (%) ≤ Si (%) + 2Al (%) -0.5(2)
  (2) By mass%: C: 0.005% or less, Si: 0.4-1.7%, Mn: 0.65-1.5%, sol.Al: 0.3-2.3%, P:0.02 %Hereinafter, S: 0.004% or less, Ti: 0.002% or less, N: 0.005% or less, the balance is Fe and impurities, and the contents of Si, Mn and Al are as follows.(1)and(2)The average grain size is 10 to 35 μm, and the integrated intensity of {222} crystal orientation parallel to the plate surface is less than 3.0 after distorted annealing at 750 ° C. for 2 hours. Semi-process non-oriented electrical steel sheet.
[0038]
    2 ≦ Si (%) + 0.5Mn (%) + Al (%) ≦ 3(1)
    Mn (%) ≤ Si (%) + 2Al (%) -0.5(2)
  (3) Hot-rolling at a billet heating temperature of 1000 to 1160 ° C, and subjecting the obtained hot-rolled sheet to box annealing at 750 to 950 ° C for 5 to 50 hours or continuous annealing at 950 to 1100 ° C, The method for producing a semi-processed non-oriented electrical steel sheet according to (1) or (2), wherein finish annealing is performed at 700 to 900 ° C. after the hot rolling.
[0039]
DETAILED DESCRIPTION OF THE INVENTION
The reason why the component range is limited in the non-oriented electrical steel sheet of the present invention is as follows. All the contents are indicated by mass%.
[0040]
C: 0.005% or less
C lowers the magnetic properties of the steel, so the lower the content, the better. If it is 0.005% or less, the effect is almost negligible. However, if it exceeds 0.005%, magnetic aging occurs and magnetic characteristics may be deteriorated during use. In addition, if it contains 0.0005% or more, the punchability may be improved.
[0041]
Si: 0.4-1.7%
Si increases the electrical resistance of the steel and increases the hardness. For this reason, it is contained for reducing iron loss and ensuring punchability, but if it is less than 0.4%, such an effect cannot be sufficiently obtained. However, if it exceeds 1.7%, it becomes too hard and wear of the punching tool increases. Therefore, the content range is 0.4 to 1.7%, but 0.6 to 1.4% is desirable to obtain preferable magnetic properties and hardness.
[0042]
Mn: 0.65 to 1.5%
Mn is usually contained in the magnetic steel sheet in an amount of about 0.2 to 0.3% so that S inevitably mixed in the steel becomes fine precipitates and does not inhibit crystal grain growth. However, Mn has an effect of bringing about a texture preferable for reduction of iron loss and magnetic properties, and in the present invention, Mn is contained more than usual. In order to fully exhibit the effect of Mn, it is necessary to contain a large amount of Si and Al, and the resulting increase in hardness and decrease in magnetic flux density are significant. Therefore, the Mn content is limited to 1.5% at most.
[0043]
sol.Al: 0.3-2.3%
sol.Al (acid-soluble Al), like Si, has the effect of increasing electrical resistance and reducing iron loss. Addition of Al can be effectively used for reducing iron loss since the hardness of steel is less increased than Si. In order to effectively utilize the action of reducing iron loss, 0.3% or more is contained. N in the steel combines with Al to form AlN. If AlN is finely dispersed, the magnetic properties are adversely affected. However, if sol. Al is contained in an amount of 0.3% or more, the AlN precipitates are coarse. It also has the effect of becoming harmless. However, if the amount of sol.Al increases, the magnetic flux density decreases. In order to fully exhibit the above-described effects of containing sol.Al, the content range is desirably 0.5 to 1.5%.
[0044]
The content ranges of individual elements of Si, Mn, and Al are as described above. When a semi-processed non-oriented electrical steel sheet containing these three elements is used, the content of each element is as follows: The formulas 1 and 2 must be satisfied.
[0045]
2 ≦ Si (%) + 0.5 Mn (%) + Al (%) ≦ 3 (1)
Mn (%) ≤ Si (%) + 2Al (%) -0.5 (2)
(1) The total amount of Si, Mn and Al in the center of the formula, that is, the value of the formula (3) above is less than 2 (%), the iron loss after strain relief annealing becomes high, and 3 (% ) Exceeds the magnetic flux density, both of which are inferior in magnetic properties. The Mn content must be in a range that satisfies the formula (2). If the Mn content exceeds this range and the Mn content is high, both iron loss and magnetic flux density are inferior.
[0046]
  P:0.02 %Less than
  P has the effect of greatly increasing the hardness when contained in a small amount, and can be effectively used when ensuring the hardness for improving punchability. However, in the present invention, the P content is0.02 %Limited to: If the amount of Mn is high,0.02 %This is because the inclusion of P in excess of the above deteriorates the magnetic properties.
[0047]
Fig. 4 shows an example of the results of examining the effects of P content on iron loss and magnetic flux density in materials with different Mn contents when investigating the effect of the main elements on the magnetic properties after strain relief annealing. 1 and FIG. In this case, Si is constant at 1.0% and Al is constant at 1.0%, and the conditions such as rolling and annealing are all the same.
[0048]
  From these figures, it can be seen that when the P content is reduced, the iron loss decreases and the magnetic flux density tends to increase. However, when the Mn content is 0.7%, compared with the case where the Mn is 0.2%, the decrease in iron loss due to the reduction in the P content is large, and the improvement in the magnetic flux density is much larger. From now on, when a large amount of Mn is contained, the P content is low, that is,0.02 %The following is clearly effective in improving the magnetic characteristics.
[0049]
  Thus, the content of P is0.02 %The magnetic properties improve as the number decreases.The
[0050]
S: 0.004% or less
S forms fine precipitates and not only inhibits the growth of crystal grains, but also deteriorates the magnetic properties. The range in which such an adverse effect does not appear is limited to 0.004% or less.
[0051]
Ti: 0.002% or less
Ti enters from the raw iron ore, etc., but combines with C, S, N, etc. to form fine precipitates, which significantly inhibits the growth of crystal grains. Therefore, it is necessary to reduce as much as possible in the semi-processed non-oriented electrical steel sheet in which crystal grain growth is performed by strain relief annealing. The range where such adverse effects do not appear remarkably is limited to 0.002% or less.
[0052]
N: 0.005% or less
N combines with Ti and Al to form fine precipitates and inhibits crystal grain growth. Therefore, it is limited to 0.005% or less so that such an effect does not appear, but the smaller the content, the better.
[0053]
The average crystal grain size of the semi-processed non-oriented electrical steel sheet is 10 to 35 μm. This is because the hardness of the steel sheet is favorable for punchability. When it is less than 10 μm, the die is too hard and wear of the punching die is likely to proceed. If it exceeds 35 μm, it may be too soft, resulting in a decrease in the dimensional accuracy of the punched product or a decrease in the yield point. Moreover, even if the crystal grain size of the steel sheet before strain relief annealing is too small or too large, the grain growth at the time of strain relief annealing is not good, so the average grain size is 10 to 35 μm.
[0054]
In the steel plate after the strain relief annealing at 750 ° C. for 2 hours, the X-ray diffraction integrated intensity of the {222} plane parallel to the plate surface is preferably less than 3.0. The integrated intensity of the {222} plane has a good correlation with iron loss and magnetic flux density, and the smaller this value, the better the magnetic properties. In the case where excellent magnetic properties are exhibited after strain relief annealing, the integrated intensity of the {222} plane is 3.0 or less. This integrated intensity is a relative intensity expressed as a ratio when the X-ray diffraction integrated intensity of {222} is 1 in an iron crystal powder sample having no texture at all, and can take a value up to 0. Since it is considered that the smaller this value is, the more preferable orientation is increased in the magnetic properties in the direction of the plate surface. Therefore, the lower limit value is not particularly defined, but is preferably 2.0 or less.
[0055]
Note that this integrated intensity is measured at a position of 1/4 thickness parallel to the plate surface because a value close to the average value at the position in the plate thickness direction is obtained.
[0056]
The above-described semi-processed non-oriented electrical steel sheet may be manufactured in accordance with a normal non-oriented electrical steel sheet manufacturing method. In particular, the following points should be considered in order to achieve the desired characteristics.
[0057]
The steel strip heating temperature for hot rolling is set to 1000 to 1160 ° C. When heated to a temperature exceeding 1160 ° C., the crystal grain growth property deteriorates, and sufficient magnetic properties cannot be obtained after strain relief annealing. This is because heating exceeding 1160 ° C. causes a precipitate phase such as MnS to be re-dissolved, resulting in harmful fine precipitates during hot rolling. However, if the heating temperature is too low, it may cause a reduction in sheet thickness accuracy in hot rolling or cold rolling, so the temperature is set to 1000 ° C. or higher.
[0058]
After hot rolling, the hot rolled sheet is annealed. This annealing has the effect of improving grain growth at the time of strain relief annealing and improving the magnetic properties, and may be a coil box annealing method or a continuous annealing method. In the case of the box annealing method, the soaking is good at 750 to 950 ° C. for 5 to 50 hours, and in the case of the continuous annealing method, heating at 950 to 1100 ° C. is sufficient. This annealing has the effect of increasing the crystal grains of the steel sheet before cold rolling and agglomerating or coarsening fine precipitates to render them harmless. When the annealing temperature or time is below the above range, such an effect cannot be obtained sufficiently, and when it exceeds the limited range, further improvement cannot be obtained and not only wasteful heating but also precipitation is caused. Re-solution of phases occurs, and the grain growth property may be deteriorated.
[0059]
The hot-rolled sheet after annealing is cold-rolled to the target thickness, but the cold rolling rate may be in the range of 60 to 90%, and may be annealed in the middle if necessary. If the cold rolling rate is within this range, it is possible to obtain an average crystal grain as a target semi-processed non-oriented electrical steel sheet product.
[0060]
Finish annealing after cold rolling is performed with a normal non-oriented electrical steel sheet continuous annealing treatment facility, but the temperature range may be 700 to 900 ° C. If the final annealing temperature is less than 700 ° C, it will not soften sufficiently and will be too hard for punching or the crystal grains will be too small.If it exceeds 900 ° C, it will be too soft for punching or the crystal grains will be too large. When the coil is formed, winding wrinkles are generated, and iron cores are likely to be poorly stacked after punching. The soaking time for annealing only needs to reach this temperature, and is not particularly limited. However, if it is too long, productivity is lowered, so it is preferable to set it to 60 seconds or less.
[0061]
【Example】
[Example 1]
The slabs having the composition shown in Table 1 are melted by vacuum melting, hot-rolled to 1150 ° C and finished to 3 mm, and these hot-rolled steel sheets are annealed at 800 ° C for 10 hours, and then the surface is descaled. -A sheet thickness of 2.3 mm was obtained by grinding and grinding, and a thickness of 0.5 mm was obtained by cold rolling. The obtained steel sheet was subjected to finish annealing at 800 ° C. for 30 seconds, and then the crystal grain size and surface hardness were measured. A 30 mm wide and 100 mm long test piece is punched from the steel sheet after finish annealing so that the length direction of the test piece is in the rolling direction and the direction perpendicular to the rolling direction, and tempered annealing is performed at 750 ° C for 2 hours. The average iron loss W with a small single-plate magnetometer_15/50And magnetic flux density B₅₀Was measured for the crystal grain size in the cross section, and the reflection integral intensity of the {222} plane was measured by X-ray diffraction at the 1/4 thickness position.
[0062]
  The results are shown in Table 2. Test numbers 2, 3, 6, 7 and 8 indicate that the magnetic characteristics after the stress relief annealing as the initial target are iron loss W_15/50Is 3.0W / kg or less, magnetic flux density B₅₀The result satisfies the criterion of 1.7 or higher. On the other hand, in test numbers 4 and 10, the iron loss exceeds 3.0 W / kg, and in test numbers 5 and 9, the magnetic flux density is lower than 1.7. Test numbers 4, 5 and 9 are all formulas(1)The test number 10 deviates from the relationship between the Si, Mn, and Al contents regulated in (1).(2)The range regulated by is not satisfied. In Test No. 1, the magnetic properties after strain relief annealing exceed the target value, but the hardness is not preferable.
[0063]
[Table 1]

[0064]
[Table 2]

[0065]
[Example 2]
Hot rolled steel sheet with a thickness of 2.3 mm that was hot rolled at a heating temperature of 1140 ° C using a steel piece with the chemical composition shown in Table 3 with a thickness of 230 mm obtained by refining in a converter and vacuum casting. It was. The hot-rolled steel sheet was annealed in a hydrogen atmosphere at 800 ° C. for 10 hours, and then cold-rolled to a thickness of 0.5 mm, subjected to finish annealing in a continuous processing line, and applied an insulating film on the surface. The steel sheet thus obtained was measured for surface hardness and crystal grain size. Specimens with a width of 30 mm and a length of 280 mm were collected from these steel plates in two directions with the length direction being the rolling direction or the width direction, and subjected to strain relief annealing at 750 ° C. for 2 hours in a nitrogen atmosphere. It was. The specimen after strain relief annealing uses an Epstein frame in accordance with JIS-C-2550 and iron loss W_15/50And magnetic flux density B₅₀Was measured. Moreover, about these test pieces, the average crystal grain diameter and the intensity | strength for {222} area in a 1/4 thickness position were also measured. Table 4 shows the measurement results of the above characteristics.
[0066]
[Table 3]

[0067]
[Table 4]

[0068]
In Table 3, steel numbers M and N are within the range defined by the present invention for chemical components, but all other numbers of steel are outside the scope of the present invention. The electrical steel sheets produced from these two types of steel have low iron loss after stress relief annealing, as is apparent from the comparison of test numbers 13 and 14 of the characteristic measurement results in Table 4 with other test results, and The result shows that the magnetic flux density is high. The {222} area strength is also lower than that of other steels.
[0069]
Example 3
About steel plates obtained by using steel pieces having chemical compositions shown as M and N in Table 3, changing the heating temperature of hot rolling, the annealing conditions of hot-rolled sheets, and the final annealing temperature after cold rolling Then, the surface hardness and the crystal grain size were measured, and further, the test piece was cut out and subjected to strain relief annealing, and then the magnetic properties and the strength for {222} area were measured. The method for measuring the characteristics of these steel plates is the same as that in Example 2. In this case, the occurrence of curl was investigated by cutting out a length of 300 mm from the inner diameter of a slit coil having an inner diameter of 510 mm and a width of 80 mm and measuring the warp height on a surface plate. These processing conditions and characteristic measurement results are shown together in Table 5.
[0070]
[Table 5]

[0071]
Steel numbers M and N are both within the range defined by the present invention in chemical composition. For this reason, in the results of Table 5, the magnetic properties after strain relief annealing are almost always W_15/50Is less than 3.0W / kg, B₅₀The initial target of over 1.70 has been achieved. And from the comparison of the results of test numbers 21, 23, 28 and 30 and the results of test numbers 19, 20, 22, 24, 25, 26, 27, 29, 31 and 32, the composition range of the present invention is obtained. It can be seen that by limiting the conditions of the steel plate manufacturing process with steel, a semi-processed non-oriented electrical steel sheet having even better post-strain annealing magnetic properties can be obtained.
[0072]
However, in test numbers 24 and 31, where the final annealing temperature is too low, the steel grains are small and hard, and in test numbers 25 and 32, where the final annealing temperature is too high, the crystal grains are too large. The curl remains on the coil, and the cut specimen is warped.
[0073]
【The invention's effect】
The semi-processed non-oriented electrical steel sheet of the present invention has a hardness that is favorable for punchability and has excellent magnetic properties after strain relief annealing. Therefore, as an iron core for electrical equipment such as a small motor and a transformer, when used with strain relief annealing, it can be a low-loss and high-efficiency equipment, which greatly contributes to industries such as energy saving.
[Brief description of the drawings]
FIG. 1 Iron loss W after strain relief annealing_15/50It is a figure which shows the influence of P content in the case where the amount of Mn is different.
Fig. 2 Magnetic flux density B after strain relief annealing₅₀It is a figure which shows the influence of P content in the case where the amount of Mn is different.

Claims (3)

In mass% C: 0.005% or less, Si: 0.4 to 1.7%, Mn: 0.65 to 1.5%, sol. Al: 0.3 to 2.3%, P: 0.02 % or less, S: 0.004% or less, Ti: 0.002% or less , N: 0.005% or less, the balance being Fe and impurities, the contents of Si, Mn and Al satisfy the following formulas (1) and (2) , and the average crystal grain size is 10 to 35 μm A semi-processed non-oriented electrical steel sheet.
2 ≦ Si (%) + 0.5Mn (%) + Al (%) ≦ 3 (1)
Mn (%) ≦ Si (%) + 2Al (%) − 0.5 (2) In mass% C: 0.005% or less, Si: 0.4 to 1.7%, Mn: 0.65 to 1.5%, sol. Al: 0.3 to 2.3%, P: 0.02 % or less, S: 0.004% or less, Ti: 0.002% or less N: 0.005% or less, the balance being Fe and impurities, the contents of Si, Mn and Al satisfy the following formulas (1) and (2) , and the average grain size is 10 to 35 μm, A semi-processed non-oriented electrical steel sheet characterized by having an integrated strength of {222} crystal orientation parallel to the plate surface of less than 3.0 after strain relief annealing at 750 ° C. for 2 hours.
2 ≦ Si (%) + 0.5Mn (%) + Al (%) ≦ 3 (1)
Mn (%) ≦ Si (%) + 2Al (%) − 0.5 (2)   After hot-rolling with a billet heating temperature of 1000-1160 ° C, the obtained hot-rolled sheet is subjected to box annealing at 750-950 ° C for 5-50 hours, or continuous annealing at 950-1100 ° C, and after cold rolling Finishing annealing is performed at 700-900 degreeC, The manufacturing method of the semi process non-oriented electrical steel sheet of Claim 1 or 2 characterized by the above-mentioned.

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