JP2003034822A - Grain-oriented electromagnetic steel sheet superior in magnetic properties - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grain-oriented electromagnetic steel sheet with improved magnetic properties by laser irradiation, in which the improvement effect on iron loss is maximized and the magnetostriction increment is restrained to the utmost. SOLUTION: The grain-oriented electromagnetic steel sheet superior in magnetic properties, of which the iron loss is improved by means of dot-sequentially irradiating one surface of the steel sheet with a pulsed laser through a condenser, is characterized in that the irradiated trace with laser is round or elliptic, and satisfies all conditions of: dl<=0.20 mm, 0.6<=(dc/Pc)<=1.0, and 0.040<=(dl/Pl)<=0.050, where a diameter of the irradiated trace in a rolling direction is defined as dl, the diameter in a sheet widthwise direction as dc, a space between the irradiated dots in the sheet widthwise direction is defined as Pc, and the space in the rolling direction as Pl.

Description

【発明の詳細な説明】 【０００１】 【発明の属する技術分野】本発明は、レーザビームを照
射した鉄損と磁歪特性に優れる方向性電磁鋼板に関する
ものである。 【０００２】 【従来の技術】従来、方向性電磁鋼板の製造方法におい
て、鋼板表面にグラス皮膜を形成し、更に絶縁コーティ
ングを施した後に板幅方向に線状で、且つ圧延方向に周
期的な応力歪みを導入し、還流磁区を形成することで18
0 °磁壁間隔を細分化し、鉄損を減少させる方法が種々
提案されてきた。中でも特開昭55-18566号公報に開示さ
れるように、鋼板の表面にパルスYAG レーザビームを集
光照射して、被照射部での皮膜の蒸発反力により歪みを
導入する方法は、鉄損改善効果が大きく、且つ非接触加
工であることから信頼性・制御性も高い優れた方向性電
磁鋼板の製造法である。 【０００３】ここでレーザ照射による鉄損改善の原理は
次のように説明される。方向性電磁鋼板の鉄損は異常渦
電流損とヒステリシス損に分離される。鋼板にレーザを
照射すると皮膜の蒸発反力により表層に応力歪みが発生
する。この歪みを源にして環流磁区が発生し、ここでの
静磁エネルギーを最小化にするように180 ゜磁区が細分
化される。その結果、180 ゜磁壁間隔に比例した渦電流
損が減少し鉄損が低下する。 【０００４】ところで方向性電磁鋼板の重要な磁気特性
として磁歪がある。磁歪は外部磁界に対する鋼板伸縮の
パラメータであり、電磁鋼板をトランスの鉄芯に使用す
る際の騒音発生の原因となる。近年のトランス低騒音化
ニーズに応えるため磁歪低減の重要性は非常に高い。レ
ーザ照射により発生する環流磁区は外部磁界を印加した
場合、磁界方向に伸縮するため一般に磁歪を増大させる
要因となり、特に外部磁界1.7〜1.9Ｔでの高磁場での磁
歪の増大が大きい。従ってレーザ照射により環流磁区を
形成することで鉄損の低減は図れるものの磁歪を増大さ
せる可能性があった。 【０００５】鉄損を十分を低下させ、且つ磁歪の増大を
極力抑制するためには最適な環流磁区導入条件、すなわ
ち最適レーザ照射条件が存在すると考えられる。しか
し、従来の技術では鉄損を低減することのみに着眼し、
その照射条件範囲も非常に広範囲である。例えば特開昭
56-51528号公報、特公昭61-49366号公報に開示されるレ
ーザ照射条件の範囲は照射ビーム径を0.01〜1mm、圧延
方向照射間隔を2.5〜20mm、板幅方向間隔0.3〜1.0mmと
なっている。このような広い照射条件範囲でもある程度
の鉄損低減効果は得られると考えられる。しかしこれら
の独立したパラメータの相関は不明確であり、鉄損改善
効果を最大化させる具体的指標はなく、また磁歪性能を
無視しているため低鉄損は得られてもトランスの騒音が
大きくなるという問題があった。 【０００６】 【発明が解決しようとする課題】本発明にて解決しよう
とする課題は、レーザ照射により磁気特性を改善した方
向性電磁鋼板として、鉄損改善効果が最大化され、且つ
磁歪増加を極力抑制した方向性電磁鋼板を提供すること
にある。 【０００７】 【課題を解決するための手段】本発明は、上記課題を解
決するもので、鋼板の一方の表面にパルスレーザを点列
に集光照射し、鉄損を改善した方向性電磁鋼板におい
て、レーザ照射痕が円形あるいは楕円形であり、照射痕
の圧延方向径をdl、板幅方向径をdc、照射痕の板幅方向
間隔をPc、圧延方向間隔をPlとしたとき、以下の条件を
全て満たすことを特徴とする磁気特性の優れた方向性電
磁鋼板である。 【０００８】 ｄl≦0.20mm 0.6≦（ｄc／Pc）≦1.0 0.040≦（ｄl／Pl）≦0.050 【０００９】 【発明の実施の形態】本発明は、パルスレーザ照射によ
って形成される照射痕形状とその間隔を限定することで
鉄損もさることながら、特に磁歪特性に優れた方向性電
磁鋼板を提供するものである。以下にその限定の根拠と
効果について実施例を用いて説明する。 【００１０】 【実施例】図１はパルスレーザの点列照射痕の模式図で
ある。圧延方向径ｄｌ、板幅方向径dcの照射痕の点列が
圧延方向に間隔Pl、板幅方向に間隔Pcで形成される。照
射痕径はレーザ集光ビーム径にほぼ一致する。レーザ照
射による歪みを起点として環流磁区が形成され、その環
流磁区幅は照射径にほぼ一致する。 【００１１】まず、照射痕の板幅方向径ｄcと板幅方向
間隔Pcの関係について説明する。効果的な鉄損改善効果
を得るためには板幅方向に連続した環流磁区を形成する
ことが好ましく、従って板幅方向に隣り合う環流磁区が
接するかあるいは重なることが好ましい。そこで点列照
射により形成される環流磁区を磁区観察用電子顕微鏡に
て詳細に観察したところ、点列間隔が大きくなり、照射
痕の板幅方向径ｄcと板幅方向照射間隔Pcが0の関係がｄ
c／Pc＜0.6の範囲では図２（ａ）に示すように隣り合う
環流磁区が接しなくなるため、連続した環流磁区が形成
されないことがわかった。また、図2（ｃ）に示す様に
隣り合う照射痕が重なり合う場合、すなわちｄc／Pc＞
1.0の範囲では一度歪みが付与された場所に更に不必要
な歪みを与えることになり非効率的であるばかりでな
く、過大な歪みによりヒステリシス損の大幅な増大につ
ながる。従って、板幅方向に切れ目なく連続した環流磁
区を効率的に形成するには図2（ｂ）に示す様な点列配
置であり、ｄcとPcの関係は0.6≦（ｄc／Pc）≦1.0とな
ることが最適である。 【００１２】 【表１】 【００１３】次に、照射痕の圧延方向径ｄlの最適な範
囲について説明する。表１はｄc／Pc＝0.67に固定し、
ｄlとPlをパラメータにレーザ照射を行った際の鉄損改
善率ηと磁歪λの測定結果である。ここでηは周波数50
Hz、最大磁束密度1.7Tにおける鉄損Ｗ17/50の改善率で
あり、次式で定義される。尚、鉄損改善量は素材に大き
く依存するため改善率の絶対値も素材によって変化す
る。しかし、同じ素材を用いる限りは改善効果は改善率
の相対値で比較することが可能である。 η=（レーザ照射前鉄損−レーザ照射後鉄損）／（レー
ザ照射前鉄損）×100（％） また、磁歪λは磁束密度1.9Ｔ、周波数50Hz、圧縮応力
0.3kg/mm2での鋼板伸縮全幅の鋼板全長に対する比率で
定義される。 【００１４】この実施例ではＱスイッチYAGレーザを使
用した。パルスエネルギーは4mJである。出力されるレ
ーザビーム形状は僅かに楕円化しており、dc／dl＝1.1
である。レーザビームを球面レンズで集光照射する場
合、dcとdlの比率は常に一定である。よってdlを変化さ
せる結果、同時にdcも変化する。そこで、本実施例では
ｄc／Pc＝0.67に固定するためにdcの変化に合わせてPc
も調整した。 【００１５】この結果より、ｄl≦0.20mmの範囲では適
当な圧延方向間隔Plを選ぶことで容易に鉄損改善率が10
％を越えることがわかったが、dl＞0.20mmでは改善率は
せいぜい10％以下であった。これはdlが大きくなると環
流磁区幅の圧延方向幅も増加し、その結果ヒステリシス
損失が増大するためであると考えられる。従って、dl＞
0.20mmの範囲では鉄損改善効果が低くくなる問題があ
り、従ってdlの範囲はｄ≦0.20mmが最適である。 【００１６】次に、Plとｄlの比率の最適範囲について
述べる。表１よりdlが0.20mm以下においてｄl／Plと鉄
損改善率ηの関係に注目するとdl／Pl＜0.04の範囲にお
いてηは10％に達せず、鉄損改善効果は低い。磁区細分
化効果は圧延方向に隣り合う環流磁区個々の細分化効果
が繋がることにより効果が増大すると考えられる。従っ
て、ある一定の環流磁区の圧延方向幅に対して間隔Plが
広くなりすぎると、その繋がりの効果が減少し、鉄損改
善率も減少するものと考えられる。ｄl／Pl≧0.04の範
囲においては隣り合う環流磁区の細分化効果が繋がり、
その結果、高い鉄損改善率が得られる。 【００１７】一方、磁歪λはdl／Plの増加に伴いの増加
することがわかった。環流磁区は圧延方向に加わる交番
磁界に対してその方向に伸縮する性質を持つ。従って、
環流磁区の量が増加すると伸縮量も増え、磁歪λが増大
する。ｄl／Plが大きいということは鋼板に占める環流
磁区体積の割合が大きいことを示すため、従って、ｄl
／Plの増加に伴いλは増加するものである。表１の結果
からｄl／Plに対してλの変化は非常に敏感であること
がわかり、ｄl／Pl＞0.05にてその増加量が顕著であっ
た。従って、磁歪の観点でのｄl／Pl≦0.05が最適な範
囲である。このように、0.04≦ｄ／Pl≦0.05が鉄損と磁
歪の両特性において同時に高い性能を得る範囲である。 【００１８】尚、本実施例では楕円ビームを用いたが、
レーザビーム形状が完全に円形であってもビームを高速
スキャンして鋼板に照射する場合も照射痕はスキャン方
向に長軸を持つ楕円となる。本発明は鋼板上に形成され
た照射痕の形状を限定することで磁気特性を大幅に改善
した製品であり、特に照射するビームの形状を限定する
ものではない。また、照射痕がdc＝dlである円形である
ことも本発明の範囲に含まれることは明らかである。 【００１９】 【発明の効果】以上説明したように、鋼板の一方の表面
にパルスレーザを点列に集光照射するに際し、レーザ照
射痕の圧延方向径、板幅方向径、照射痕の板幅方向間
隔、圧延方向間隔を特定の条件下で制御することで高い
鉄損改善効果とともに磁歪の増加を極力抑えた方向性電
磁鋼板が得られるという利点を有する。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grain-oriented electrical steel sheet having excellent iron loss and magnetostriction characteristics when irradiated with a laser beam. 2. Description of the Related Art Conventionally, in a method for manufacturing a grain-oriented electrical steel sheet, a glass film is formed on the surface of the steel sheet, and after applying an insulating coating, the glass film is linearly formed in the sheet width direction and periodically formed in the rolling direction. By introducing stress strain and forming a return domain, 18
Various methods of subdividing the 0 ° domain wall interval to reduce iron loss have been proposed. Among them, as disclosed in Japanese Patent Application Laid-Open No. 55-18566, a method of condensing and irradiating a pulsed YAG laser beam onto the surface of a steel sheet to introduce distortion by the evaporation reaction force of the film at the irradiated portion is iron. This is a method for producing a grain-oriented electrical steel sheet having a large loss improvement effect and excellent reliability and controllability due to non-contact processing. Here, the principle of iron loss improvement by laser irradiation is explained as follows. Iron loss of grain-oriented electrical steel sheet is separated into abnormal eddy current loss and hysteresis loss. When a steel sheet is irradiated with a laser, stress distortion occurs in the surface layer due to the evaporation reaction force of the film. Due to this distortion, a return magnetic domain is generated, and the 180 ° magnetic domain is subdivided so as to minimize the magnetostatic energy there. As a result, the eddy current loss proportional to the 180 ° domain wall interval decreases, and the iron loss decreases. An important magnetic property of a grain-oriented electrical steel sheet is magnetostriction. Magnetostriction is a parameter of expansion and contraction of a steel sheet with respect to an external magnetic field, and causes noise when an electromagnetic steel sheet is used for an iron core of a transformer. The importance of reducing magnetostriction is extremely high in order to meet the recent needs for transformer noise reduction. When an external magnetic field is applied, the reflux magnetic domain generated by laser irradiation expands and contracts in the direction of the magnetic field, which generally causes an increase in magnetostriction. In particular, the increase in magnetostriction at a high magnetic field with an external magnetic field of 1.7 to 1.9 T is large. Therefore, by forming a circulating magnetic domain by laser irradiation, iron loss can be reduced, but magnetostriction may be increased. [0005] In order to sufficiently reduce iron loss and to suppress the increase in magnetostriction as much as possible, it is considered that there are optimal conditions for introducing magnetic domains, that is, optimal laser irradiation conditions. However, the conventional technology focuses only on reducing iron loss,
The range of irradiation conditions is very wide. For example,
No. 56-51528, the range of laser irradiation conditions disclosed in JP-B-61-49366 is irradiation beam diameter of 0.01 to 1 mm, rolling direction irradiation interval of 2.5 to 20 mm, plate width direction interval of 0.3 to 1.0 mm. ing. It is considered that a certain iron loss reduction effect can be obtained even in such a wide irradiation condition range. However, the correlation between these independent parameters is unclear, there is no specific index to maximize the iron loss improvement effect, and transformer noise is large even if low iron loss is obtained because the magnetostriction performance is ignored. There was a problem of becoming. The problem to be solved by the present invention is to provide a grain-oriented electrical steel sheet having improved magnetic properties by laser irradiation, in which the iron loss improving effect is maximized and the magnetostriction is increased. An object of the present invention is to provide a grain-oriented electrical steel sheet that is suppressed as much as possible. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a grain-oriented electrical steel sheet in which one surface of a steel sheet is focused and irradiated with a pulse laser in a point sequence to improve iron loss. In, the laser irradiation mark is circular or elliptical, the rolling direction diameter of the irradiation mark is dl, the plate width direction diameter is dc, the plate width direction interval of the irradiation mark is Pc, the rolling direction interval is Pl, the following: This is a grain-oriented electrical steel sheet having excellent magnetic properties, satisfying all the conditions. Dl ≦ 0.20 mm 0.6 ≦ (dc / Pc) ≦ 1.0 0.040 ≦ (dl / Pl) ≦ 0.050 DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an irradiation mark shape formed by pulsed laser irradiation. An object of the present invention is to provide a grain-oriented electrical steel sheet having particularly excellent magnetostriction characteristics while reducing iron loss by limiting the interval. Hereinafter, the grounds and effects of the limitation will be described using examples. FIG. 1 is a schematic view of a pulse train irradiation spot of a pulse laser. A dot sequence of irradiation marks having a diameter dl in the rolling direction and a diameter dc in the sheet width direction is formed with an interval Pl in the rolling direction and an interval Pc in the sheet width direction. The irradiation mark diameter substantially matches the laser focused beam diameter. A return magnetic domain is formed starting from the distortion caused by the laser irradiation, and the width of the return magnetic domain is substantially equal to the irradiation diameter. First, the relationship between the diameter dc of the irradiation mark in the plate width direction and the interval Pc in the plate width direction will be described. In order to obtain an effective iron loss improvement effect, it is preferable to form continuous magnetic domains continuous in the sheet width direction, and therefore it is preferable that adjacent magnetic domains adjacent to each other in the sheet width direction contact or overlap. Therefore, when the reflux magnetic domains formed by the point array irradiation were observed in detail by an electron microscope for observing magnetic domains, the point array interval became large, and the relationship between the plate width direction diameter dc of the irradiation mark and the plate width direction irradiation interval Pc was 0. Is d
In the range of c / Pc <0.6, as shown in FIG. 2 (a), it was found that adjacent reflux magnetic domains did not come into contact with each other, so that continuous reflux magnetic domains were not formed. In addition, as shown in FIG. 2C, when the adjacent irradiation marks overlap, that is, dc / Pc>
In the range of 1.0, unnecessary distortion is applied to a place where distortion has been applied once, which is not only inefficient, but also causes excessive increase in hysteresis loss due to excessive distortion. Therefore, in order to efficiently form a continuous continuous magnetic domain in the plate width direction, a dot array as shown in FIG. 2B is used, and the relation between dc and Pc is 0.6 ≦ (dc / Pc) ≦ 1.0 Optimally, [Table 1] Next, the optimum range of the diameter dl of the irradiation mark in the rolling direction will be described. Table 1 fixes dc / Pc = 0.67,
9 shows measurement results of an iron loss improvement rate η and a magnetostriction λ when laser irradiation is performed using dl and Pl as parameters. Where η is the frequency 50
Hz, the improvement rate of iron loss W17 / 50 at a maximum magnetic flux density of 1.7 T, defined by the following equation. Since the iron loss improvement amount largely depends on the material, the absolute value of the improvement rate also changes depending on the material. However, as long as the same material is used, the improvement effect can be compared with the relative value of the improvement rate. η = (iron loss before laser irradiation-iron loss after laser irradiation) / (iron loss before laser irradiation) × 100 (%) The magnetostriction λ is magnetic flux density 1.9T, frequency 50Hz, compressive stress
It is defined as the ratio of the total width of the steel plate at 0.3 kg / mm2 to the total length of the steel plate. In this embodiment, a Q-switched YAG laser is used. The pulse energy is 4 mJ. The output laser beam shape is slightly elliptical, dc / dl = 1.1
It is. When a laser beam is focused and irradiated by a spherical lens, the ratio between dc and dl is always constant. Therefore, as a result of changing dl, dc also changes at the same time. Therefore, in this embodiment, in order to fix dc / Pc = 0.67, Pc is adjusted according to the change of dc.
Was also adjusted. From these results, in the range of dl ≦ 0.20 mm, the iron loss improvement rate can be easily increased by selecting an appropriate interval Pl in the rolling direction.
%, But when dl> 0.20 mm, the improvement rate was at most 10% or less. This is considered to be because as dl increases, the width of the magnetic domain width in the rolling direction also increases, and as a result, the hysteresis loss increases. Therefore, dl>
In the range of 0.20 mm, there is a problem that the effect of improving iron loss is reduced. Therefore, the range of dl is optimally d ≦ 0.20 mm. Next, the optimum range of the ratio between Pl and dl will be described. Focusing on the relationship between dl / Pl and the iron loss improvement rate η when dl is 0.20 mm or less from Table 1, η does not reach 10% in the range of dl / Pl <0.04, and the iron loss improvement effect is low. It is considered that the magnetic domain refining effect is increased by connecting the refining effect of each of the convection magnetic domains adjacent to each other in the rolling direction. Therefore, it is considered that if the interval Pl is too large with respect to a certain width of the convection magnetic domain in the rolling direction, the effect of the connection is reduced and the iron loss improvement rate is also reduced. In the range of dl / Pl ≧ 0.04, the effect of subdividing adjacent convection magnetic domains is connected,
As a result, a high iron loss improvement rate is obtained. On the other hand, it was found that the magnetostriction λ increases with an increase in dl / Pl. The circulating magnetic domain has the property of expanding and contracting in the direction of the alternating magnetic field applied in the rolling direction. Therefore,
As the amount of the circulating magnetic domains increases, the amount of expansion and contraction also increases, and the magnetostriction λ increases. The fact that dl / Pl is large indicates that the ratio of the circulating magnetic domain volume to the steel sheet is large.
Λ increases with an increase in / Pl. From the results in Table 1, it was found that the change of λ was very sensitive to dl / Pl, and the increase was remarkable when dl / Pl> 0.05. Therefore, dl / Pl ≦ 0.05 from the viewpoint of magnetostriction is the optimum range. Thus, 0.04 ≦ d / Pl ≦ 0.05 is a range in which high performance is simultaneously obtained in both the iron loss and the magnetostriction characteristics. Although an elliptical beam is used in this embodiment,
Even when the shape of the laser beam is completely circular, when the beam is scanned at a high speed to irradiate the steel sheet, the irradiation mark becomes an ellipse having a long axis in the scanning direction. The present invention is a product in which the magnetic characteristics are significantly improved by limiting the shape of the irradiation mark formed on the steel plate, and does not particularly limit the shape of the beam to be irradiated. Further, it is apparent that the irradiation mark is a circle with dc = dl, which is also included in the scope of the present invention. As described above, when a pulsed laser beam is condensed and irradiated on one surface of a steel sheet in a point sequence, the diameter of the laser irradiation mark in the rolling direction, the width of the sheet width, and the width of the irradiation mark By controlling the direction interval and the rolling direction interval under specific conditions, there is an advantage that a grain-oriented electrical steel sheet in which an increase in magnetostriction is suppressed as much as possible can be obtained together with a high iron loss improving effect.

【図面の簡単な説明】 【図１】パルスレーザを点列照射して磁気特性を改善し
た方向性電磁鋼板の照射痕の説明図である。 【図２】レーザ照射後の方向性電磁鋼板の磁区構造の模
式図で、照射痕の板幅方向間隔Pcと照射痕径dl、deおよ
び環流磁区構造の関係を示し、（ａ）はdc／Pc＜0.6の
場合、（ｂ）は0.6≦（dc／Pc）≦1.0の場合、（ｃ）は
dc／Pc＞1.0の場合の環流磁区構造を示す図である。 【符号の説明】 dl…パルスレーザ照射痕の圧延方向径 dc…パルスレーザ照射痕の板幅方向径 Pc…照射痕の板幅方向間隔 Pl…照射痕の圧延方向間隔 Pg…180゜磁区磁壁間隔 η…磁束密度1.7T、周波数50Hzにおける鉄損のレーザ照
射による改善率 λ…磁束密度1.9Ｔ、周波数50Hz、圧縮応力0.3kg/mm2に
おける磁歪 １…方向性電磁鋼板 ２…レーザ照射痕 ３…環流磁区 ４…180°磁区BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of irradiation marks on a grain-oriented electrical steel sheet whose magnetic properties have been improved by irradiating a pulse laser in a point sequence. FIG. 2 is a schematic view of the magnetic domain structure of a grain-oriented electrical steel sheet after laser irradiation, showing the relationship between the interval Pc in the width direction of the irradiation mark, the irradiation mark diameters dl, de, and the reflux magnetic domain structure; If Pc <0.6, (b) is 0.6 ≦ (dc / Pc) ≦ 1.0, (c) is
It is a figure which shows the circulating magnetic domain structure in case of dc / Pc> 1.0. [Description of Signs] dl: Rolling direction diameter of pulsed laser irradiation mark dc: Plate width direction diameter of pulsed laser irradiation mark Pc: Width of irradiation mark in width direction Pl: Rolling direction of irradiation mark Pg: 180 ° Magnetic domain wall gap η: Magnetic flux density 1.7T, improvement rate of iron loss at a frequency of 50Hz by laser irradiation λ: Magnetic strain at a magnetic flux density of 1.9T, frequency 50Hz, compressive stress 0.3kg / mm2 1. Magnetic domain 4… 180 ° magnetic domain

───────────────────────────────────────────────────── フロントページの続き (72)発明者 浜田 直也 千葉県富津市新富20−１ 新日本製鐵株式 会社技術開発本部内 (72)発明者 新井 聡 兵庫県姫路市広畑区富士町１番地 新日本 製鐵株式会社広畑製鐵所内 (72)発明者 難波 英一 兵庫県姫路市広畑区富士町１番地 新日本 製鐵株式会社広畑製鐵所内 Ｆターム(参考） 4K033 AA02 PA08 5E041 AA02 CA01 CA10    ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Naoya Hamada             20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation             Company Technology Development Division (72) Inventor Satoshi Arai             New Japan, 1 Fuji-machi, Hirohata-ku, Himeji-shi, Hyogo             Inside Hirohata Works of Steel Works, Ltd. (72) Inventor Eiichi Namba             New Japan, 1 Fuji-machi, Hirohata-ku, Himeji-shi, Hyogo             Inside Hirohata Works of Steel Works, Ltd. F term (reference) 4K033 AA02 PA08                 5E041 AA02 CA01 CA10

Claims (1)

【特許請求の範囲】 【請求項１】 鋼板の一方の表面にパルスレーザを点列
に集光照射し、鉄損を改善した方向性電磁鋼板におい
て、レーザ照射痕が円形あるいは楕円形であり、レーザ
照射痕の圧延方向長さをdl、板幅方向長さをdc、照射痕
の板幅方向間隔をPc、圧延方向間隔をPlとしたとき、以
下の条件を全て満たすことを特徴とする磁気特性の優れ
た方向性電磁鋼板。 ｄl≦0.20mm 0.6≦（ｄc／Pc）≦1.0 0.040≦（ｄl／Pl）≦0.050Claims 1. In a grain-oriented electrical steel sheet in which a pulse laser is condensed and irradiated in a point sequence on one surface of a steel sheet to improve iron loss, a laser irradiation mark is circular or elliptical, When the length of the laser irradiation mark in the rolling direction is dl, the length in the sheet width direction is dc, the interval in the sheet width direction of the irradiation mark is Pc, and the interval in the rolling direction is Pl, the following conditions are all satisfied: Grain-oriented electrical steel sheet with excellent properties. dl ≦ 0.20mm 0.6 ≦ (dc / Pc) ≦ 1.0 0.040 ≦ (dl / Pl) ≦ 0.050