TWI898965B - Hot rolled annealed sheet and its manufacturing method and non-oriented electromagnetic steel sheet manufacturing method - Google Patents

Abstract

The present invention provides a hot-rolled annealing technology for electromagnetic steel sheets with excellent cold-rollability. The hot-rolled annealed sheet has a composition comprising, by mass%, C: 0.010% or less, Si: 1.0% to 5.0%, Mn: 0.05% to 5.0%, P: 0.10% or less, S: 0.010% or less, Al: 3.0% or less, N: 0.0080% or less, and O: 0.0050% or less, with the remainder consisting of Fe and unavoidable impurities. The recrystallized structure ratio (Re/Rc) between the center and edge of the sheet width is 0.95 or less. A method for producing a hot-rolled annealed sheet comprises hot-rolling a steel material having the aforementioned composition to obtain a hot-rolled sheet, and then annealing the hot-rolled sheet. During the hot-rolled sheet annealing, the center of the sheet width of the hot-rolled sheet is heated from room temperature to a holding temperature and held thereat, while the edge of the hot-rolled sheet is heated from room temperature to a maximum temperature lower than the holding temperature, such that the temperature increase rate Vc of the center of the sheet width is greater than the temperature increase rate Ve of the edge by at least 1.0°C/second.

Description

Hot rolled annealed sheet and its manufacturing method and non-oriented electromagnetic steel sheet manufacturing method

The present invention relates to a hot-rolled annealed sheet and a method for manufacturing the same, as well as a method for manufacturing a non-oriented electromagnetic steel sheet.

In recent years, environmental concerns, such as those related to global warming, have led to demands for reducing _CO2 emissions and conserving energy. In particular, in the automotive sector, hybrid electric vehicles (HEVs) combining an engine and motor, electric vehicles (EVs) powered solely by electric motors, and fuel cell electric vehicles (FCEVs) are being developed. To improve motor efficiency, the motors used in these HEVs, EVs, and FCEVs are typically driven at high frequencies, which facilitate high-speed rotation. These motors are often made of non-oriented electromagnetic steel (NOES). To achieve high motor efficiency, these steels are strongly required to have low iron loss characteristics at high frequencies.

Traditionally, non-oriented electromagnetic steel (NOS) sheets have been manufactured by increasing their intrinsic resistance through the addition of alloying elements such as Si and Al, or by reducing the sheet thickness to reduce eddy current losses. However, the addition of large amounts of alloying elements reduces the ductility and toughness of the steel sheet, leading to frequent cracking during the cold rolling process.

As a technology for suppressing cracks in high-alloy steel, for example, Patent Document 1 discloses a method for producing non-oriented electromagnetic steel sheets with high magnetic flux density. This method involves cold rolling a rapidly solidified casting at 180°C to 350°C to suppress cracking during the cold rolling process. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 2004-110985

[The problem that the invention aims to solve]

However, while the technology described in Patent Document 1 can suppress cracking by cold rolling within a temperature range of 180°C to 350°C, it is difficult to maintain the steel plate at a high temperature during rolling, and there is also the problem of lubricating oil burning onto equipment such as the rollers, causing damage.

The present invention aims to resolve the aforementioned problems faced by conventional technologies by providing a hot-rolled annealed sheet that exhibits excellent cold-rollability in subsequent steps without degrading the magnetic properties of the final non-oriented electromagnetic steel sheet, and to propose an advantageous method for manufacturing the same. Furthermore, another object is to propose a method for manufacturing non-oriented electromagnetic steel sheet using the hot-rolled annealed sheet. Here, cold-rollability includes both fracture resistance and edge cracking resistance. [Solution]

The inventors' extensive research revealed that, in most cases, cold-rolling-induced fractures originate at the edges of the steel strip. Therefore, they discovered that, even without improving the fracture resistance of the entire steel strip, simply improving the fracture resistance of the strip edges significantly reduces the risk of cold-rolling-induced fractures or cracks. Furthermore, they discovered that a method for improving the fracture resistance of the strip edges is to retain an unrecrystallized structure at the strip edges and create a difference in the recrystallized structure ratio between the center and edges of the strip. This method, compared to reducing the recrystallized structure ratio of the entire strip, can more effectively improve fracture resistance while preventing a decrease in magnetic properties.

That is, the hot rolled annealed sheet of the present invention, which is advantageous in solving the above-mentioned problems, is characterized in that it has a composition comprising, in mass%, C: 0.010% or less, Si: 1.0% or more and 5.0% or less, Mn: 0.05% or more and 5.0% or less, P: 0.10% or less, S: 0.010% or less, Al: 3.0% or less, N: 0.0080% or less, and O: 0.0050% or less, and further optionally contains at least one element selected from the following groups: Group A: selected from Sn: 0.001% or more and 0.20% or less, and Sb: one or two of 0.001% to 0.20%; Group B: at least one selected from Ca: 0.0001% to 0.10%, Mg: 0.0001% to 0.10%, and rare earth metals (REM): 0.0001% to 0.10%; Group C: one or two selected from B: 0.002% to 0.20%, and Mo: 0.002% to 0.20%; Group D: Zn: 0.0005% to 0.0050%; Group E: Ni: 0 0.01% to 1.0%; F group: Cr: 0.1% to 5.0%; G group: Cu: 0.005% to 1.0%; H group: at least one selected from Ti: 0.001% to 0.010%, V: 0.001% to 0.050%, Nb: 0.001% to 0.005%, Ta: 0.0001% to 0.0020%, W: 0.001% to 0.050%, Pb: 0.0001% to 0.0020%; I group: Co: J Group: one or two selected from Ga: 0.0005% to 0.0300% and Ge: 0.0005% to 0.0300%; and K Group: As: 0.001% to 0.020%, with the remainder consisting of Fe and unavoidable impurities, and the ratio Re of the recrystallized structure at a position Xe of the steel plate at the outermost edge of the plate width, 10 mm away in the width direction, relative to the ratio Rc of the recrystallized structure at the center of the plate width Xc, i.e., Re/Rc, is 0.95 or less.

Furthermore, the hot-rolled annealed sheet of the present invention further preferably satisfies one or both of the following conditions: the recrystallized structure ratio Rc in the center portion Xc of the sheet width is 80% or greater, and the recrystallized structure ratio Re at the steel sheet position Xe is within a range of 5% to 95%.

In addition, the method for manufacturing a hot-rolled annealed sheet according to the present invention, which advantageously solves the above-mentioned problem, is a method for manufacturing any of the above-mentioned hot-rolled annealed sheets, characterized in that the method for manufacturing the hot-rolled annealed sheet comprises: a hot-rolling step of hot-rolling a steel material having the above-mentioned composition to obtain a hot-rolled sheet; and a hot-rolled sheet annealing step of hot-rolled sheet annealing the hot-rolled sheet; in the hot-rolled sheet annealing step, while heating a central portion Xc of the hot-rolled sheet width from room temperature to a holding temperature _T1 and holding the same, a steel sheet position Xe at a distance of 10 mm in the width direction from the outermost portion of the sheet width of the hot-rolled sheet reaches a maximum temperature _T2 lower than the holding temperature T1 from room temperature _. , so that the temperature rise rate Vc of the central portion Xc of the plate width is greater than the temperature rise rate Ve of the steel plate position Xe by more than 1.0°C/second.

In addition, the manufacturing method of the hot-rolled annealed plate involved in the present invention satisfies: (a) in the hot-rolled plate annealing step, at least one of the following (1) to (4) is satisfied; or (b) when the hot-rolled plate annealing step is performed on a hot-rolled plate with a plate width W in the range of 900 mm to 1100 mm, a heating inhibition zone is set in a range from a distance of more than 20 mm in the width direction from the outermost edge of the plate width to a distance of less than 0.250×W in the width direction from the outermost edge of the plate width, which is a more preferred means of solving the problem. (1) The holding temperature _T1 of the central portion Xc of the hot-rolled plate is set to 900°C or higher; (2) The holding time t1 of the central portion Xc of the hot-rolled plate at the holding temperature _T1 is set to a range of ₂ seconds to 120 seconds; (3) The maximum temperature _T2 at the steel plate position Xe is set to a range of 750°C to 1000°C; and (4) The time _t2 during which the temperature is above the maximum temperature _T2 -50°C (maximum temperature _T2 minus 50°C) is set to a range of 5 seconds to 20 seconds.

The method for manufacturing a non-oriented electromagnetic steel sheet of the present invention, which advantageously solves the above-mentioned problem, is characterized in that any of the above-mentioned hot-rolled annealed sheets is cold-rolled to obtain a cold-rolled sheet, and the cold-rolled sheet is finish-annealed to obtain a cold-rolled annealed sheet.

Furthermore, in the present invention, "edges" refer to both widthwise edges. However, application to both sides is not necessary; even application to just one side is effective in reducing fractures. For example, if the characteristics of a roller cause edge cracking or fracture to occur preferentially on one side, applying this technology to just one side can also achieve a fracture reduction effect. [Effects of the Invention]

The present invention provides a hot-rolled annealed sheet with excellent cold-rollability. Furthermore, the hot-rolled annealed sheet can be used to produce non-oriented electromagnetic steel sheets with high magnetic flux density, high frequency, and low iron loss.

The following describes embodiments of the present invention and the reasons for their limitations. [Hot-rolled Annealed Sheet] <Steel Sheet Composition> The preferred composition of a hot-rolled annealed sheet according to one embodiment of the present invention is described. The unit of element content in the composition is "mass %." Unless otherwise specified, the following information is expressed in "%."

<Basic Composition> C: 0.010% or less C is a harmful element that causes magnetic aging in non-oriented electromagnetic steel sheets, forming carbides and increasing steel loss. Therefore, its adverse effects become significant when the content exceeds 0.010%, so the C content in the steel sheet is set to 0.010% or less. It is preferably set to 0.004% or less. While there is no specific lower limit for the C content, steel sheets with excessively low C content are very expensive, so it is preferably set to approximately 0.0001%.

Si: 1.0% or more, 5.0% or less Si increases the intrinsic resistivity of steel, reduces iron loss, and improves steel strength through solid solution strengthening. To achieve these effects, the Si content should be 1.0% or more. On the other hand, exceeding 5.0% significantly reduces the saturation magnetic flux density, leading to a significant decrease in magnetic flux density. Therefore, the upper limit is set to 5.0% or less. Therefore, the Si content is set within the range of 1.0% or more and 5.0% or less. It is preferably 1.5% or more, and more preferably less than 4.5%. It is more preferably 2.0% or more, and even more preferably less than 4.0%.

Mn: 0.05% or more, 5.0% or less Mn, like Si, is an element useful for increasing the intrinsic resistivity and strength of steel. To achieve these effects, a Mn content of 0.05% or more is required. On the other hand, a content exceeding 5.0% may promote the precipitation of MnC and degrade magnetic properties. Therefore, the upper limit of the Mn content is set at 5.0%. Therefore, the Mn content is set within the range of 0.05% or more and 5.0% or less. It is preferably 0.1% or more and preferably 3.0% or less.

P: 0.10% or less P is a useful element for adjusting the strength (hardness) of steel. However, if the P content exceeds 0.10%, toughness decreases, making cracking more likely during processing. Therefore, the upper limit of the P content is set at 0.10%. While there is no specific lower limit, steel sheets with excessively low P content become very expensive, so the P content is preferably kept at 0.001% or more. A P content of 0.08% or less is preferred, and 0.003% or more is even more preferred.

S: 0.010% or less S is an element that forms fine precipitates and adversely affects steel wear properties. This adverse effect becomes significant when the content exceeds 0.010%. Therefore, the S content is kept to 0.010% or less, more preferably 0.008% or less. While there is no specific lower limit, steel sheets with excessively low S content become very expensive, so the S content is preferably kept to 0.0001% or more, more preferably 0.0003% or more, and even more preferably 0.005% or less.

Al: 3.0% or less Excessive addition of Al may promote nitriding of the steel sheet surface, degrading magnetic properties. Therefore, the Al content should be kept to 3.0% or less, more preferably 2.0% or less. Furthermore, Al, like Si, is a useful element that increases the intrinsic resistivity of steel and reduces iron loss. To achieve these effects, an addition of 0.005% or more is preferred, with a more preferred addition of 0.010% or more, and even more preferably, 0.015% or more.

N: 0.0080% or less N is an element that forms fine precipitates and adversely affects steel wear properties. This adverse effect becomes significant when the content exceeds 0.0080%, so the content is kept to 0.0080% or less. It is preferably 0.0030% or less. While there is no specific lower limit, steel sheets with excessively low N content are very expensive. Therefore, the N content is preferably kept to 0.0005% or more, and more preferably 0.0008% or more.

O: 0.0050% or less O (oxygen) is an element that forms non-metallic inclusions in molten steel, adversely affecting iron-wear properties. Its adverse effects become significant when the content exceeds 0.0050%. Therefore, the O content is kept to 0.0050% or less, preferably 0.0030% or less. While there is no specific lower limit, steel with excessively low O content becomes very expensive, so the O content is preferably kept to 0.0005% or more, and more preferably 0.0008% or more.

The hot-rolled annealed sheet according to this embodiment comprises: C: 0.010% or less, Si: 1.0% or more and 5.0% or less, Mn: 0.05% or more and 5.0% or less, P: 0.10% or less, S: 0.010% or less, Al: 3.0% or less, N: 0.0080% or less, and O: 0.0050% or less, with the remainder containing Fe and unavoidable impurities. In addition to the basic composition described above, depending on the required properties, any element from at least one of the following groups A to K may be contained.

Group A: One or both of Sn: 0.001% to 0.20% and Sb: 0.001% to 0.20% Sn: 0.001% to 0.20% Sn is an element that effectively improves magnetic flux density and reduces iron loss by improving the microstructure. To achieve this effect, the Sn content should be at least 0.001%. On the other hand, a Sn content exceeding 0.20% will saturate the effect, leading to unnecessary cost increases. Therefore, the upper limit of the Sn content is preferably set at 0.20%. Therefore, the Sn content is preferably within the range of 0.001% to 0.20%.

Sb: 0.001% or more, 0.20% or less Sb is an element that effectively increases magnetic flux density and reduces iron loss by improving the microstructure. To achieve this effect, the Sb content should be at least 0.001%. On the other hand, if the Sb content exceeds 0.20%, the effect is saturated, resulting in an unnecessary increase in cost. Therefore, the upper limit of the Sb content is preferably set at 0.20%. Therefore, the Sb content is preferably within the range of 0.001% or more and 0.20% or less.

Group B: At least one selected from Ca: 0.0001% to 0.10%, Mg: 0.0001% to 0.10%, and rare earth metals (REM): 0.0001% to 0.10%. Ca: 0.0001% to 0.10%. Ca is an element that binds sulfur (S) as sulfides, contributing to the reduction of iron losses. To achieve this effect, a Ca content of 0.0001% or more is sufficient. On the other hand, a Ca content exceeding 0.10% will saturate the effect, leading to unnecessary cost increases. Therefore, the upper limit of the Ca content is preferably set at 0.10%. Therefore, the Ca content is preferably within the range of 0.0001% to 0.10%.

Mg: 0.0001% or more to 0.10% or less Mg is an element that fixes sulfur (S) as sulfides, contributing to reduced iron losses. To achieve this effect, the Mg content should be at least 0.0001%. However, exceeding 0.10% Mg reduces the effect, leading to unnecessary cost increases. Therefore, the upper limit of the Mg content is preferably set at 0.10%. Therefore, the Mg content is preferably within the range of 0.0001% to 0.10%.

REM (rare earth metal elements): 0.0001% or more to 0.10% or less REM (rare earth metals) are a group of elements that bind sulfur (S) as sulfides, contributing to the reduction of iron losses. To achieve this effect, the REM content should be at least 0.0001%. However, if the REM content exceeds 0.10%, the effect is saturated, leading to unnecessary cost increases. Therefore, the upper limit is set at 0.10%. Therefore, the REM content is preferably within the range of 0.0001% to 0.10%.

Group C: One or both of B: 0.002% to 0.20% and Mo: 0.002% to 0.20% B: 0.002% to 0.20% B forms fine carbides in steel, increasing the strength of the steel sheet. To achieve this effect, a B content of 0.002% or more is sufficient. On the other hand, a B content exceeding 0.20% results in excessive carbide formation, increasing steel loss. Therefore, the upper limit of the B content is preferably set at 0.20%. Therefore, the B content is preferably within the range of 0.002% to 0.20%.

Mo: 0.002% to 0.20% Mo forms fine carbides in steel, increasing the strength of the steel sheet. To achieve this effect, the Mo content should be at least 0.01%. On the other hand, a Mo content exceeding 0.20% leads to excessive carbide formation and increased steel loss. Therefore, the upper limit of the Mo content is preferably set at 0.20%. Therefore, the Mo content is preferably within the range of 0.01% to 0.20%.

Group D: Zn: 0.0005% or more to 0.0050% or less Zn is an element that effectively increases magnetic flux density and reduces iron loss by improving the microstructure. To achieve this effect, a Zn content of 0.0005% or more is sufficient. On the other hand, a Zn content exceeding 0.0050% will saturate the effect, leading to an unnecessary increase in cost. Therefore, the upper limit of the Zn content is preferably set at 0.0050%. Therefore, the Zn content is preferably within the range of 0.0005% or more to 0.0050%.

Group E: Ni: 0.01% to 1.0% Nitride is an element that improves the toughness of steel and can be added appropriately. To achieve this effect, a Ni content of 0.01% or more is sufficient. However, the effect is saturated when the Ni content exceeds 1.0%, so the upper limit is set at 1.0%. Therefore, the Ni content is preferably within the range of 0.01% to 1.0%.

Group F: Cr: 0.1% or more to 5.0% or less Cr increases the intrinsic resistivity of steel and reduces iron loss. To achieve this effect, the Cr content should be at least 0.05%. However, a Cr content exceeding 5.0% significantly reduces the saturation magnetic flux density, resulting in a decrease in magnetic flux density. Therefore, the upper limit is set at 5.0%. Therefore, the Cr content is preferably within the range of 0.05% to 5.0%.

G Group: Cu: 0.005% or more to 1.0% or less Cu is an element that improves the toughness of steel and can be added appropriately. To achieve this effect, the Cu content should be at least 0.01%. However, the effect is saturated when the Cu content exceeds 1.0%, so when adding Cu, the upper limit is set to 1.0%. Therefore, the Cu content is preferably within the range of 0.005% or more to 1.0%.

H Group: At least one element selected from the group consisting of Ti: 0.001% to 0.010%; V: 0.001% to 0.050%; Nb: 0.001% to 0.005%; Ta: 0.0001% to 0.0020%; W: 0.001% to 0.050%; and Pb: 0.0001% to 0.0020%. Ti is an element that increases the strength of steel sheets and can be added appropriately. To achieve this effect, a Ti content of 0.001% or more is sufficient. However, a Ti content exceeding 0.010% results in fine precipitates in the steel sheet, increasing iron loss. Therefore, the upper limit of the Ti content is preferably 0.010%.

V: 0.001% or more, 0.050% or less V is an element that increases the strength of steel sheets and can be added appropriately. To achieve this effect, the V content should be at least 0.001%. However, if the V content exceeds 0.050%, fine precipitates will form in the steel sheet, increasing iron loss. Therefore, the upper limit of the V content is preferably 0.050%.

Nb: 0.001% or more to 0.005% or less Nb is an element that increases the strength of steel sheets and can be added appropriately. To achieve this effect, the Nb content should be at least 0.001%. However, if the Nb content exceeds 0.005%, fine precipitates will form in the steel sheet, increasing iron loss. Therefore, the upper limit of the V content is preferably set to 0.005%.

Ta: 0.0001% or more to 0.0020% or less Ta is an element that increases the strength of steel sheets and can be added appropriately. To achieve this effect, the Ta content should be at least 0.0001%. However, if the Ta content exceeds 0.0020%, fine precipitates will form in the steel sheet, increasing iron loss. Therefore, the upper limit of the Ta content is preferably 0.0020%.

W: 0.001% or more, 0.050% or less W is an element that increases the strength of steel sheets and can be added appropriately. To achieve this effect, the W content should be at least 0.001%. However, if the W content exceeds 0.050%, fine precipitates will form in the steel sheet, increasing iron loss. Therefore, the upper limit of the W content is preferably 0.050%.

Pb: 0.0001% or more, 0.0020% or less Pb is an element that increases the strength of steel sheets and can be added appropriately. To achieve this effect, the Pb content should be at least 0.0001%. However, if the Pb content exceeds 0.0020%, fine precipitates will form in the steel sheet, increasing iron loss. Therefore, the upper limit of the Pb content is preferably 0.0020%.

Group I: Co: 0.001% or more to 0.100% or less Co is an element that increases the magnetic flux density of steel sheets and can be added appropriately. To achieve this effect, the Co content should be at least 0.001%. However, increasing the Co content significantly increases alloy costs, so the upper limit of the Co content is preferably 0.100%.

Group J: One or both of Ga: 0.0005% to 0.0300% and Ge: 0.0005% to 0.0300% Ga: 0.0005% to 0.0300% Ga is an element that improves the steel sheet's texture and increases magnetic flux density, and can be added appropriately. To achieve these effects, a Ga content of 0.0005% or more is sufficient. However, adding large amounts of Ga not only diminishes these effects but also increases alloy costs. Therefore, the upper limit of the Ga content is preferably 0.0300%.

Ge: 0.0005% or more, 0.0300% or less Ge is an element that improves the steel sheet's microstructure and increases magnetic flux density, and can be added appropriately. To achieve these effects, a Ge content of 0.0005% or more is sufficient. However, adding large amounts of Ge not only diminishes the effects but also increases alloy costs. Therefore, the upper limit of the Ge content is preferably 0.0300%.

K Group: As: 0.001% or more to 0.020% or less As is an element that increases the strength of steel sheets and can be added appropriately. To achieve this effect, the As content should be at least 0.001%. However, an As content exceeding 0.020% increases the risk of cold rolling cracking. Therefore, the upper limit of the As content is preferably 0.020%.

When the content of any of the above elements is below the appropriate range for effective action, it will not affect the cold rollability or magnetic properties of the electromagnetic steel sheet product and is therefore permitted as an unavoidable impurity.

<Steel Sheet Microstructure> Next, the microstructure of the hot-rolled annealed steel sheet of this embodiment will be described. Recrystallization, as used herein, refers to the formation and growth of grains with significantly reduced dislocation density by maintaining the material at a high temperature. Recrystallized and non-recrystallized structures can be distinguished by observation under an optical microscope.

The ratio Re/Rc of the recrystallized structure ratio Re at the outermost edge of the sheet width at a distance of 10 mm in the width direction relative to the recrystallized structure ratio Rc at the center of the sheet width Xc is 0.95 or less. The inventors' research has shown that by creating a difference in the recrystallized structure ratio between the center and the edge of the sheet width, fracture and edge cracking during the cold rolling step are significantly suppressed compared to simply reducing the recrystallized structure ratio of the entire hot-rolled annealed sheet. The inventors' reasoning for this is as follows. Generally speaking, as the recrystallized structure ratio decreases, the work hardening rate to plastic deformation decreases. Because the work hardening rate at the plate width edge is lower than that at the plate width center, it is speculated that stress acts during rolling, reducing the tension at the plate width edge. Consequently, the initiation of cracks at the plate width edge is significantly suppressed, and fracture and edge cracking are thought to be reduced. Specifically, by setting the ratio Re/Rc (the recrystallized structure ratio Re at a position Xe 10 mm away in the width direction at the extreme edge of the plate width relative to the recrystallized structure ratio Rc at the plate width center Xc of the hot-rolled annealed plate) to 0.95 or less, a hot-rolled annealed plate can be obtained in which fracture and edge cracking during cold rolling are sufficiently suppressed. This ratio is preferably 0.8 or less, and more preferably 0.7 or less. The lower limit does not need to be particularly restricted, but the hot-rolled annealed sheet produced using the method described below is usually 0.05 or higher.

Recrystallized Texture Rc in the Center of the Sheet Width Xc is 80% or More The hot-rolled annealed sheet of this embodiment controls the ratio of the recrystallized texture ratio Rc in the center of the sheet width to the recrystallized texture ratio Re at the edge of the sheet width at a location Xe. The effects of the present invention are not limited by the recrystallized texture ratio value in the center of the sheet width itself. On the other hand, there is an appropriate range for the recrystallized texture ratio in the center of the sheet width, and within this range, the effects of the present invention are more pronounced. When the recrystallized texture ratio in the center of the sheet width Xc is 80% or more, the magnetic properties of the final product are less likely to deteriorate. For this reason, the recrystallized texture ratio Rc in the center of the sheet width Xc is more preferably 80% or more.

The recrystallized structure ratio Re at position Xe on the width edge side is within a range of 5% to 95%. In the hot-rolled annealed sheet of this embodiment, the ratio of the recrystallized structure ratio Rc at the center of the sheet width to the recrystallized structure ratio Re at position Xe on the width edge side is controlled. The effect of the present invention is not limited by the recrystallized structure ratio value at position Xe itself. On the other hand, there is an appropriate range for the recrystallized structure ratio at position Xe, and the effect of the present invention is more pronounced within this range. In the hot-rolled annealed sheet of this embodiment, when the recrystallized structure ratio Re at position Xe on the width edge side is 5% or more, the sheet width edge is prevented from becoming excessively hard, and the formation of fracture starting points is suppressed. On the other hand, when the recrystallized structure ratio Re at position Xe on the plate width edge side is 95% or less, the fracture suppression effect brought about by the control ratio Re/Rc described above is more likely to be significantly exerted. Based on the above, the recrystallized structure ratio Re at position Xe on the plate width edge side is preferably within the range of 5% to 95%.

[Hot-Rolled Annealed Sheet Manufacturing Conditions] Next, the method for manufacturing the hot-rolled annealed sheet according to this embodiment will be described. Generally speaking, the hot-rolled annealed sheet according to this embodiment is obtained by sequentially hot-rolling and hot-rolled annealing a steel material having the aforementioned composition. In this embodiment, as long as the composition and hot-rolled annealing conditions fall within the scope of the patent claims, conventionally known methods may be employed for the remaining aspects.

<Steel Material> The steel material is not particularly limited as long as it has the above-mentioned composition. The smelting method and composition adjustment method of the steel material are not particularly limited. Known smelting methods using rotary furnaces, electric furnaces, vacuum degassing equipment, and other equipment and methods can be employed. From the perspective of production efficiency, it is preferred to produce steel slabs (steel material) by continuous casting after smelting. Alternatively, steel slabs or thin billets can be produced by known casting methods such as ingot-slab rolling or thin billet continuous casting.

<Hot Rolling Step> The hot rolling step is performed by hot rolling the steel material having the above-mentioned composition to obtain a hot-rolled sheet. The hot rolling step involves heating the steel material having the above-mentioned composition and hot rolling it to obtain a hot-rolled sheet of a specified size. The hot rolling step is not particularly limited, and any commonly used hot rolling step can be applied.

A common example of a hot rolling process is the following. For example, the steel material is heated to a temperature between 1000°C and 1200°C. The heated steel material is then hot rolled at a finish rolling exit temperature between 800°C and 950°C. After hot rolling, appropriate post-rolling cooling is applied, for example, at an average cooling rate between 20°C/s and 100°C/s within a temperature range of 450°C and 950°C. The steel is then coiled at a coiling temperature between 400°C and 700°C to produce a hot-rolled sheet of specified dimensions and shape.

<Hot-rolled sheet annealing step> The hot-rolled sheet annealing step is a step of annealing the hot-rolled sheet by heating and holding it at an elevated temperature. More specifically, while the center width portion Xc of the hot-rolled sheet is heated to and held at a suitable holding temperature _T1 for recrystallization, the hot-rolled sheet is then brought from room temperature to a maximum temperature _T2 , which is lower than the holding temperature _T1 , at a position Xe of the sheet located 10 mm in the width direction at the extreme edge of the sheet. Furthermore, the heating rate Vc of the center width portion Xc is set to be at least 1.0°C/second greater than the heating rate Ve at the position Xe. Furthermore, the holding temperature _T1 is preferably 900°C or higher. The holding time _t1 at the holding temperature T1 is preferably set to a range of 2 seconds to 120 seconds. The maximum temperature _T2 at the steel plate position Xe is preferably set to a range of 750°C to 1000°C. The time _t2 during which the maximum temperature _T2 at the steel plate position Xe is above -50°C (maximum temperature _T2 minus 50°C) is _preferably set to a range of 5 seconds to 20 seconds. It is preferred that when a hot-rolled plate having a plate width W in the range of 900 mm to 1100 mm is subjected to the above-mentioned hot-rolled plate annealing step, a heating inhibition zone is provided in a range from a distance of 20 mm or more from the outermost edge of the plate in the width direction to a distance of 0.250×W or less from the outermost edge of the plate in the width direction.

Furthermore, a pickling step is typically performed after the hot-rolled sheet annealing step. The pickling step is not particularly limited, as long as it allows the pickling to be performed to a degree that allows the pickled steel sheet to be cold rolled. For example, conventional pickling steps using hydrochloric acid or sulfuric acid can be applied. This pickling step can be performed continuously within the same production line as the hot-rolled sheet annealing step or in a separate production line. The hot-rolled annealed sheet in the present invention includes both unpickled (black skin) and pickled (white skin) sheets.

The heating rate Vc at the center of the sheet width Xc is set to be at least 1.0°C/second greater than the heating rate Ve at the steel plate position Xe. During the hot-rolled sheet annealing step, the heating rate Vc is used when the sheet width center Xc is heated from room temperature to the holding temperature _T1 . Furthermore, the heating rate Ve is used when the sheet width reaches its maximum temperature _T2 at the steel plate position Xe, 10 mm away in the width direction, at the extreme edge of the sheet width. The constraint is: Vc - Ve ≥ 1.0°C/second. When Vc - Ve is less than 1.0°C/second, the difference in the ratio of the recrystallized structure between the center and the edge of the plate width decreases, and the ratio Re of the recrystallized structure at the outermost edge of the plate width relative to the ratio Rc of the recrystallized structure at the center of the plate width (Re/Rc) cannot be reduced to less than 0.95. Vc - Ve is preferably ≥ 3.0°C/second, and more preferably ≥ 5.0°C/second.

Holding Temperature _T1 of the Plate Width Center Xc is 900°C or Higher During the hot-rolled plate annealing step, the holding temperature _T1 of the plate width center Xc is preferably set to 900°C or higher. Setting _T1 to 900°C or higher allows the recrystallized structure ratio Rc in the plate width center Xc to reach 80% or higher. While there is no specific upper limit, if _T1 exceeds 1100°C, heat conduction may cause the plate width edges to heat up, potentially leading to an excessive increase in the recrystallized structure ratio at the plate width edges. Therefore, it is preferable to control the holding temperature _T1 of the plate width center Xc to between 900°C and 1100°C.

The holding time _t1 of the holding temperature T1 in the center portion Xc _of the sheet width is preferably set to 2 seconds or longer and 120 seconds or shorter during the hot rolled sheet annealing step. A holding time _t1 of 120 seconds or shorter allows the ratio Re/ _Rc of the recrystallized structure between the center portion and the edge portion of the sheet width to be kept below 0.95, thus improving cold rollability. Furthermore, by setting _the lower limit of the holding time _t1 to 2 seconds, the recrystallization and grain growth caused by the hot rolled sheet annealing are sufficient, resulting in improved magnetic properties. Therefore, the holding time _t1 of the holding temperature _T1 in the center portion Xc of the sheet width is preferably set to 2 seconds or longer and 120 seconds or shorter.

The maximum temperature _T2 at the steel plate position Xe is set within a range of 750°C to 1000°C. During the hot-rolled plate annealing step, the maximum temperature _T2 at the steel plate position Xe, located 10 mm from the widthwise extreme edge of the hot-rolled plate, is preferably set to 750°C to 1000°C. When the maximum temperature _T2 is 750°C or higher, recrystallization at the steel plate position Xe is sufficient, and the recrystallized structure ratio Re satisfies 5% or higher. On the other hand, when the maximum temperature _T2 is 1000°C or lower, the recrystallized structure ratio Re satisfies 95% or lower. Therefore, the maximum temperature _T2 at the steel plate position Xe is preferably set to 750°C to 1000°C. The maximum temperature _T2 at the steel plate position Xe must be lower than the holding temperature _T1 at the center of the plate width Xc. Otherwise, the recrystallized structure ratio Re at the steel plate position Xe will be higher than the recrystallized structure ratio Rc at the center of the plate width Xc.

<Time _t2 During the Steel Sheet Position Xe Reaches a Maximum Temperature of _-50 °C or Higher> Set to 5 Seconds or More and 20 Seconds or Less> During the hot-rolled sheet annealing step, the time _t2 during which the steel sheet reaches a maximum temperature of _-50 °C or higher at position Xe is preferably set to 5 seconds or more and 20 seconds or less. Note that _t2 is the sum of the time required to heat _the steel sheet to the maximum temperature _T2 and the time required to cool the steel sheet from the maximum temperature T2. When _t2 is 5 seconds or more, sufficient time is ensured from the time the steel sheet reaches the maximum temperature _T2 until cooling, allowing for proper recrystallization and achieving a recrystallized structure ratio Re of 5% or more. When _t2 is 20 seconds or less, recrystallization proceeds moderately, and the ratio Re of the recrystallized structure can be made 95% or less.

"Providing a heating suppression zone at a distance of 20 mm or more from the outermost edge of the sheet in the width direction" During the hot-rolled sheet annealing step, when providing a heating suppression zone that intentionally creates a temperature variation across the sheet width, the following methods are possible: (A) preventing overheating by reducing burner heating only at the edges; (B) preventing overheating by covering the edges with a cover; (C) applying a temperature-inhibiting material that suppresses radiant heating at a low emissivity; and (D) preventing overheating at a low emissivity by removing black scale only at the edges. Any method that intentionally creates a temperature variation is acceptable and does not limit the scope of the invention. It is preferable to provide a heating suppression zone at least 20 mm from the outermost edge of the plate width in the width direction. When the heating suppression zone is at least 20 mm from the outermost edge of the plate width, the temperature at the steel plate position Xe, 10 mm from the outermost edge, is less likely to rise due to heat conduction through the steel plate. Consequently, the temperature rise rate Vc at the center of the plate width Xc can be set at least 1.0°C/second higher than the temperature rise rate Ve at the aforementioned steel plate position Xe. On the other hand, regarding the upper limit of the heating suppression zone, when hot-rolled sheet with a width W of 900 mm to 1100 mm is subjected to the hot-rolled sheet annealing step described above, it is preferable to provide the heating suppression zone within a widthwise distance of 0.250 × W or less from the outermost edge of the sheet. Within this range, the recrystallized structure ratio of the entire steel sheet is sufficient, which can suppress the deterioration of magnetic properties. Therefore, it is preferable to set the heating suppression zone within a widthwise distance of 20 mm or more from the outermost edge of the sheet. When hot-rolled sheet with a width W of 900 mm to 1100 mm is subjected to the hot-rolled sheet annealing step, the heating suppression zone is preferably set to a distance of 0.250 × W or less from the outermost edge of the sheet in the width direction.

<Pickling Step> The pickling step involves pickling the hot-rolled and annealed steel sheet after the hot-rolled and annealed step. The pickling step is not particularly limited, as long as it allows the steel sheet to be pickled to a level sufficient for cold rolling. For example, conventional pickling steps using hydrochloric acid or sulfuric acid can be used. This pickling step can be performed continuously within the same production line as the hot-rolled and annealed steel sheet, or in a different production line.

<Cold Rolling Step> The cold rolling step involves cold rolling the pickled, hot-rolled, annealed sheet (pickled sheet). The cold rolling step is a step in which the pickled, hot-rolled, annealed sheet is cold rolled to obtain a cold-rolled sheet. The cold rolling step is not particularly limited, as long as it produces a cold-rolled sheet of a specified size. Conventional cold rolling steps can be used.

A common cold rolling process involves, for example, using a five-station tandem mill to roll the pickled sheet to a specific size and shape at a total reduction of at least 80% but less than 95%. The number of stations can be four or fewer, or six or more.

<Final Annealing Step> The final annealing step is a step in which the cold-rolled sheet is annealed to obtain a cold-rolled annealed sheet. The final annealing step is not particularly limited, as long as the cold-rolled sheet is heated, held, and cooled to obtain a cold-rolled annealed sheet; conventional annealing steps can be applied. Furthermore, an insulating coating may be applied to the surface after the final annealing step. The method and type of insulating coating are not particularly limited; conventional insulating coating steps can be applied.

A common annealing step, for example, involves heating the cold-rolled sheet to a temperature between 800°C and 1200°C in a non-oxidizing atmosphere, holding the temperature for 5 to 60 seconds, and then cooling the sheet. Examples

The present invention will be described in detail below with reference to the following embodiments. However, the present invention is not limited thereto.

<Production of Hot-Rolled Annealed Sheet> Molten steel having the composition shown in Table 1 was melted using a conventional method and continuously cast into 230 mm thick steel sheet (steel material). The resulting steel sheet was hot-rolled to obtain a 2.0 mm thick hot-rolled sheet. The resulting hot-rolled sheet was then hot-rolled and pickled under the conditions shown in Tables 2-1 and 2-2 to obtain hot-rolled annealed sheet (pickled sheet).

<Cold-rolled Steel Sheet Manufacturing> The hot-rolled annealed steel sheet (pickled steel sheet) is then cold-rolled at room temperature using a tandem rolling mill to a thickness of 0.25 mm to obtain cold-rolled steel sheet.

<Production of Cold-Rolled Annealed Sheet> The cold-rolled sheet is then held at 1000°C for 10 seconds in a non-oxidizing atmosphere for final annealing using a known method. The sheet is then coated using a known method to obtain a cold-rolled annealed sheet (non-oriented electromagnetic steel sheet).

[Table 1] Steel No. Ingredient composition (mass %) Remarks carbon Si Mn P S Al N O other A 0.002 3.0 0.22 0.01 0.002 1.1 0.0026 0.0017 - Invention of steel B 0.005 3.2 0.25 0.01 0.003 0.9 0.0019 0.0013 - Invention of steel C 0.010 3.1 0.18 0.01 0.003 0.9 0.0019 0.0011 - Invention of steel D 0.015 2.9 0.21 0.02 0.003 1.1 0.0019 0.0011 - Compare Steel E 0.002 0.9 0.23 0.01 0.002 0.9 0.0017 0.0016 - Compare Steel F 0.002 1.1 0.23 0.01 0.003 0.9 0.0023 0.0016 - Invention of steel G 0.002 2.1 0.24 0.01 0.002 1.0 0.0022 0.0010 - Invention of steel H 0.002 4.8 0.18 0.01 0.002 1.0 0.0018 0.0015 - Invention of steel I 0.002 5.1 0.22 0.02 0.002 0.9 0.0018 0.0010 - Compare Steel J 0.002 2.8 0.04 0.01 0.003 1.1 0.0024 0.0012 - Compare Steel K 0.002 3.1 0.06 0.01 0.003 0.9 0.0015 0.0009 - Invention of steel L 0.002 2.9 0.50 0.01 0.003 1.1 0.0017 0.0017 - Invention of steel M 0.002 2.8 4.9 0.01 0.002 0.9 0.0018 0.0009 - Invention of steel N 0.002 3.2 5.1 0.01 0.004 0.9 0.0018 0.0016 - Compare Steel O 0.002 2.9 0.23 0.05 0.002 0.9 0.0024 0.0014 - Invention of steel P 0.002 3.0 0.25 0.09 0.002 0.9 0.0016 0.0009 - Invention of steel Q 0.002 3.0 0.23 0.11 0.002 1.0 0.0016 0.0013 - Compare Steel R 0.002 3.1 0.19 0.01 0.005 1.0 0.0020 0.0009 - Invention of steel S 0.002 3.0 0.26 0.01 0.010 0.9 0.0021 0.0009 - Invention of steel T 0.002 3.0 0.21 0.01 0.011 1.0 0.0026 0.0009 - Compare Steel U 0.002 2.9 0.22 0.01 0.003 1.5 0.0015 0.0014 - Invention of steel V 0.002 2.8 0.22 0.01 0.003 2.9 0.0022 0.0012 - Invention of steel W 0.002 2.9 0.26 0.01 0.002 3.1 0.0017 0.0009 - Compare Steel X 0.002 3.1 0.23 0.01 0.002 1.1 0.0026 0.0008 - Invention of steel Y 0.002 3.1 0.26 0.01 0.003 0.9 0.0026 0.0011 - Invention of steel Z 0.002 2.8 0.25 0.01 0.003 1.0 0.0100 0.0012 - Compare Steel AA 0.002 2.9 0.20 0.01 0.002 1.1 0.0025 0.0032 - Invention of steel AB 0.002 2.8 0.19 0.01 0.003 1.0 0.0025 0.0049 - Invention of steel AC 0.003 2.9 0.25 0.01 0.002 1.0 0.0023 0.0055 - Compare Steel AD 0.002 3.0 0.20 0.01 0.003 1.1 0.0027 0.0016 Sn: 0.15, Sb: 0.15, Ca: 0.08, Mg: 0.08, REM: 0.08, B: 0.15, Mo: 0.15, Zn: 0.0045, Ni: 0.8, Cr: 1.2, Cu: 0.9 Invention of steel AE 0.002 3.0 0.26 0.01 0.001 1.0 0.0023 0.0016 - Invention of steel AF 0.002 3.1 0.24 0.01 0.002 0.005 0.0018 0.0010 - Invention of steel AG 0.002 3.1 0.21 0.01 0.003 1.1 0.0017 0.0017 Ti: 0.005, V: 0.03, Nb: 00.003, Ta: 0.001, W: 0.03, Pb: 0.001, Co: 0.05, Ga: 0.01, Ge: 0.01, As: 0.01 Invention of steel Note: - indicates the unavoidable level of impurities. Italic underlined text indicates outside the scope of invention.

[Table 2-1] Processing No. Steel No. Vc Ve Vc-Ve T ₁ T ₂ t ₁ t ₂ X1 Method for suppressing heating of edges Remarks °C/second °C/second °C/second °C °C Second Second mm 1 A 41.2 40.3 0.9 979 818 20 11 30 Edge occlusion Comparative example 2 A 35.3 34.0 1.3 1017 848 13 14 50 Edge occlusion Invention Example 3 A 32.2 26.8 5.4 973 841 11 11 60 Edge occlusion Invention Example 4 A 16.6 8.5 8.1 894 834 17 9 30 Edge occlusion Invention Example 5 A 37.4 29.0 8.4 902 824 29 12 40 Edge occlusion Invention Example 6 A 15.2 7.0 8.2 996 745 twenty one 12 40 Edge occlusion Invention Example 7 A 27.0 19.1 7.9 1023 755 twenty two 16 40 Edge occlusion Invention Example 8 A 21.5 14.1 7.4 1047 993 13 13 60 Edge occlusion Invention Example 9 A 24.2 16.5 7.7 1006 1010 20 15 30 Edge occlusion Comparative example 10 A 32.1 23.6 8.5 1032 811 1 16 50 Edge occlusion Invention Example 11 A 25.4 18.9 6.5 1040 845 2 13 30 Edge occlusion Invention Example 12 A 21.1 12.9 8.2 969 848 118 9 40 Edge occlusion Invention Example 13 A 28.6 20.4 8.2 1045 843 125 11 40 Edge occlusion Comparative example 14 A 21.3 13.9 7.4 992 805 twenty three 4 40 Edge occlusion Invention Example 15 A 18.9 10.6 8.3 991 823 28 5 30 Edge occlusion Invention Example 16 A 32.8 25.9 6.9 1001 832 29 20 50 Edge occlusion Invention Example 17 A 43.6 36.6 7.0 1001 822 14 twenty two 40 Edge occlusion Comparative example 18 A 22.3 15.3 7.0 1022 836 18 14 15 Edge occlusion Comparative example 19 A 29.1 21.0 8.1 1017 816 29 13 20 Edge occlusion Invention Example 20 A 24.2 17.0 7.2 957 812 29 14 245 Edge occlusion Invention Example twenty one A 23.1 15.7 7.4 1016 825 18 12 255 Edge occlusion Invention Example twenty two B 21.6 14.8 6.8 971 817 29 9 50 Edge occlusion Invention Example twenty three C 32.1 24.7 7.4 1006 820 16 10 50 Edge occlusion Invention Example twenty four D 20.8 13.3 7.5 1027 835 13 8 60 Edge occlusion Comparative example 25 E 23.0 16.1 6.9 1014 842 10 11 50 Edge occlusion Comparative example 26 F 43.7 35.3 8.4 973 810 twenty three 10 40 Edge occlusion Invention Example 27 G 27.8 21.3 6.5 1035 821 twenty three 10 60 Edge occlusion Invention Example 28 H 37.1 29.6 7.5 997 844 20 8 50 Edge occlusion Invention Example 29 I 19.9 12.6 7.3 987 828 29 9 60 Edge occlusion Comparative example 30 J 40.7 33.3 7.4 1015 827 twenty three 12 40 Edge occlusion Comparative example Italic underlined parts: indicate that they are outside the scope of the invention.

[Table 2-2] Processing No. Steel No. Vc Ve Vc-Ve T ₁ T ₂ t ₁ t ₂ X1 Method for suppressing heating of edges Remarks °C/second °C/second °C/second °C °C Second Second mm 31 K 38.8 30.6 8.2 992 827 13 14 40 Edge occlusion Invention Example 32 L 43.9 35.7 8.2 994 811 twenty one 14 40 Edge occlusion Invention Example 33 M 44.9 38.4 6.5 998 808 15 10 60 Edge occlusion Invention Example 34 N 28.0 21.0 7.0 954 841 28 8 30 Edge occlusion Comparative example 35 O 18.0 10.8 7.2 984 818 14 10 50 Edge occlusion Invention Example 36 P 36.3 28.1 8.2 954 820 26 14 60 Edge occlusion Invention Example 37 Q 42.8 35.3 7.5 1018 807 twenty one 13 40 Edge occlusion Comparative example 38 R 18.4 11.4 7.0 1021 840 twenty one 10 30 Edge occlusion Invention Example 39 S 39.1 31.3 7.8 1042 830 30 14 50 Edge occlusion Invention Example 40 T 18.0 11.4 6.6 1017 833 17 14 30 Edge occlusion Comparative example 41 U 44.6 37.8 6.8 1001 801 twenty one 14 60 Edge occlusion Invention Example 42 V 15.3 7.1 8.2 1033 804 10 8 50 Edge occlusion Invention Example 43 W 34.7 26.2 8.5 974 812 15 8 50 Edge occlusion Comparative example 44 X 28.8 21.9 6.9 972 804 29 9 30 Edge occlusion Invention Example 45 Y 22.8 14.9 7.9 1047 806 12 16 30 Edge occlusion Invention Example 46 Z 30.7 23.3 7.4 1035 839 10 11 50 Edge occlusion Comparative example 47 AA 42.2 35.2 7.0 1003 812 17 13 60 Edge occlusion Invention Example 48 AB 23.6 16.0 7.6 1018 815 19 11 50 Edge occlusion Invention Example 49 AC 15.3 7.0 8.3 1006 811 19 10 60 Edge occlusion Comparative example 50 AD 17.4 10.1 7.3 981 845 30 10 50 Edge occlusion Invention Example 51 AE 38.8 30.6 8.2 992 827 13 14 40 Edge occlusion Invention Example 52 AF 18.4 11.4 7.0 1021 840 twenty one 10 30 Edge occlusion Invention Example 53 A 29.5 22.2 7.3 999 850 27 13 60 Grinding to remove oxide scale Invention Example 54 B 39.2 30.9 8.3 999 840 20 9 40 Grinding to remove oxide scale Invention Example 55 C 29.4 20.9 8.5 979 801 twenty two 10 40 Grinding to remove oxide scale Invention Example 56 D 35.6 27.1 8.5 999 840 twenty four 14 30 Grinding to remove oxide scale Comparative example 57 E 18.8 12.1 6.7 1002 801 20 12 40 Grinding to remove oxide scale Comparative example 58 F 44.5 36.3 8.2 1031 824 10 9 50 Grinding to remove oxide scale Invention Example 59 AG 43.9 35.4 8.5 974 817 29 14 40 Edge occlusion Invention Example Italic underlined parts: indicate that they are outside the scope of the invention.

<Evaluation> ≪Microstructure Observation≫ Test specimens for microstructure observation were taken from the center of the hot-rolled annealed steel sheet and 10 mm from the outermost edge. These specimens were then embedded in resin, with a cross section through the steel sheet thickness as the observation surface. The specimens were observed using an optical microscope to measure the recrystallized structure ratio.

Rollability Evaluation The number of edge cracks per 1000 m of cold-rolled steel was investigated. Edge cracks with a length of 2 mm or greater were counted as N. Cold-rolled steel with a number of 2.0 or fewer edge cracks per 1000 m was considered to have good cold rollability.

Magnetic Property Evaluation: Magnetic test specimens 30 mm wide and 280 mm long, with their longitudinal directions oriented in the rolling direction and perpendicular to the rolling direction, were taken from the cold-rolled annealed sheets. The magnetic flux density (B50) and iron loss (W10 _/400) of the cold-rolled annealed sheets were measured using the Epstein method according to JIS C2550-1:2011. A B50 value of 1.55T was considered good for magnetic flux density, and a W10 _/400 value of 14.0W/kg after annealing was considered good for iron loss.

In the evaluation column, "No" was assigned to any steel sheet that exhibited cracks during cold rolling or had an edge crack count exceeding 2.0 per 1000 m of cold-rolled sheet. Furthermore, regardless of the hot-rolled sheet annealing conditions, the evaluation was "No" for any steel sheet with a composition outside the scope of the present invention and a magnetic flux density (B50) below 1.55 T or a steel loss ratio (W10 _/400) exceeding 14.0 W/kg. Of the remaining steel sheets, "Excellent" was assigned to any steel sheet with a magnetic flux density (B50) of 1.55 T or higher and a steel loss ratio (W10 _/400) of 14.0 W/kg or lower, and "Good" was assigned to any other steel sheet.

[Table 3-1] Processing No. R _C Re Re/Rc Cold rolling fracture Number of edge fractures N B50 W _10/400 evaluate Remarks % % % Yes or No Piece T W/kg 1 99 96 0.97 - 2.4 1.59 12.5 no Comparative example 2 100 92 0.92 - 1.2 1.54 12.7 good Invention Example 3 99 74 0.75 - 0.4 1.64 12.1 Excellent Invention Example 4 75 47 0.63 - 0 1.62 14.1 good Invention Example 5 82 51 0.62 - 0 1.56 13.8 Excellent Invention Example 6 81 4 0.05 - 1.8 1.54 12.5 good Invention Example 7 83 12 0.14 - 1.9 1.57 12.2 Excellent Invention Example 8 96 81 0.84 - 1.6 1.67 12.3 Excellent Invention Example 9 100 97 0.97 - 2.3 1.67 12.7 no Comparative example 10 77 52 0.67 - 0 1.65 14.2 good Invention Example 11 84 50 0.60 - 0 1.56 13.7 Excellent Invention Example 12 96 84 0.88 - 1.5 1.65 12.7 Excellent Invention Example 13 100 98 0.98 - 2.2 1.60 12.3 no Comparative example 14 82 4 0.05 - 1.9 1.60 11.6 Excellent Invention Example 15 86 8 0.09 - 1.9 1.62 11.9 Excellent Invention Example 16 100 88 0.88 - 1.6 1.62 11.6 Excellent Invention Example 17 100 96 0.96 - 2.4 1.67 11.6 no Comparative example 18 100 97 0.97 - 2.8 1.70 11.6 no Comparative example 19 100 87 0.87 - 0 1.56 11.6 Excellent Invention Example 20 95 67 0.70 - 0 1.67 13.7 Excellent Invention Example twenty one 75 48 0.64 - 0 1.62 14.2 good Invention Example twenty two 97 68 0.70 - 0 1.60 12.7 Excellent Invention Example twenty three 95 64 0.67 - 0 1.59 13.6 Excellent Invention Example twenty four 96 62 0.65 - 0 1.64 14.4 no Comparative example 25 100 66 0.66 - 0 1.72 16.3 no Comparative example 26 98 66 0.67 - 0 1.68 13.9 Excellent Invention Example 27 100 65 0.65 - 0 1.70 13.2 Excellent Invention Example 28 95 62 0.65 - 1.3 1.56 10.4 Excellent Invention Example 29 98 69 0.70 - 1.9 1.52 10.1 no Comparative example 30 100 67 0.67 - 0 1.61 14.3 no Comparative example Italic underlined parts: indicate that they are outside the scope of the invention.

[Table 3-2] Processing No. R _C Re Re/Rc Cold rolling fracture Number of edge fractures N B50 W _10/400 evaluate Remarks % % % Yes or No Piece T W/kg 31 95 61 0.64 - 0 1.67 13.5 Excellent Invention Example 32 96 60 0.62 - 0 1.65 11.5 Excellent Invention Example 33 97 66 0.68 - 0 1.48 12.9 good Invention Example 34 99 69 0.70 - 0 1.52 14.3 no Comparative example 35 96 60 0.63 - 0.5 1.66 11.8 Excellent Invention Example 36 99 67 0.68 - 1.7 1.58 11.3 Excellent Invention Example 37 98 69 0.70 have 3.1 1.62 11.8 no Comparative example 38 99 68 0.69 - 0 1.56 13.1 Excellent Invention Example 39 95 66 0.69 - 0 1.71 13.9 Excellent Invention Example 40 99 62 0.63 - 0 1.64 14.5 no Comparative example 41 99 60 0.61 - 0.3 1.68 10.9 Excellent Invention Example 42 99 61 0.62 - 1.1 1.57 13.7 Excellent Invention Example 43 98 68 0.69 - 1.7 1.63 14.2 no Comparative example 44 98 69 0.70 - 0 1.70 12.1 Excellent Invention Example 45 96 62 0.65 - 0 1.71 13.8 Excellent Invention Example 46 96 60 0.63 - 0 1.66 14.5 no Comparative example 47 97 62 0.64 - 0 1.63 12.2 Excellent Invention Example 48 99 61 0.62 - 0 1.66 13.6 Excellent Invention Example 49 98 69 0.70 - 0 1.71 14.1 no Comparative example 50 95 67 0.70 - 0 1.63 11.9 Excellent Invention Example 51 95 66 0.69 - 0 1.65 13.1 Excellent Invention Example 52 96 62 0.65 - 0 1.72 12.9 Excellent Invention Example 53 100 70 0.70 - 0 1.70 12.2 Excellent Invention Example 54 96 61 0.64 - 0 1.60 12.4 Excellent Invention Example 55 97 63 0.65 - 0 1.54 13.8 good Invention Example 56 95 57 0.60 - 0 1.71 14.1 no Comparative example 57 96 65 0.68 - 0 1.64 17.1 no Comparative example 58 99 63 0.64 - 0 1.64 13.7 Excellent Invention Example 59 96 61 0.65 - 0 1.71 12.2 Excellent Invention Example Italic underlined parts: indicate that they are outside the scope of the invention.

As can be seen from the results in Tables 3-1 and 3-2, all of the hot rolled annealed sheets of the present invention have excellent cold rolling properties. In addition, the cold rolled annealed sheets obtained by cold rolling and annealing the hot rolled annealed sheets of the present invention also have excellent magnetic properties.

without

without

Claims (7)

A hot-rolled annealed sheet having a composition comprising, by mass%, C: 0.010% or less, Si: 1.0% or more and 5.0% or less, Mn: 0.05% or more and 5.0% or less, P: 0.10% or less, S: 0.010% or less, Al: 3.0% or less, N: 0.0080% or less, and O: 0.0050% or less. Furthermore, the sheet may optionally contain at least one element selected from the following groups: Group A: one or two selected from Sn: 0.001% or more and 0.20% or less, and Sb: 0.001% or more and 0.20% or less. Group B: At least one selected from Ca (0.0001% to 0.10%), Mg (0.0001% to 0.10%), and rare earth metals (0.0001% to 0.10%). Group C: One or two selected from B (0.002% to 0.20%) and Mo (0.002% to 0.20%). Group D: Zn (0.0005% to 0.0050%). Group E: Ni (0.01% to 1.0%). Group F: Cr (0.1% to 5.0%). Group G: Cu (0.005% to 1.0%). H Group: At least one selected from the group consisting of Ti: 0.001% to 0.010%, V: 0.001% to 0.050%, Nb: 0.001% to 0.005%, Ta: 0.0001% to 0.0020%, W: 0.001% to 0.050%, and Pb: 0.0001% to 0.0020%. I Group: Co: 0.001% to 0.100%. J Group: One or two selected from the group consisting of Ga: 0.0005% to 0.0300%, and Ge: 0.0005% to 0.0300%. K Group: As: 0.001% to 0.020%, with the remainder consisting of Fe and unavoidable impurities. The ratio of the recrystallized structure Re at the outermost edge of the plate width at a distance of 10 mm in the width direction to the recrystallized structure Rc at the center of the plate width Xc, i.e., Re/Rc, is 0.95 or less. The hot-rolled annealed sheet according to claim 1, further satisfying either or both of the following: a recrystallized structure ratio Rc at the center portion Xc of the sheet width is 80% or greater, and a recrystallized structure ratio Re at the steel sheet position Xe is within a range of 5% to 95%. A method for manufacturing a hot-rolled annealed sheet, comprising manufacturing the hot-rolled annealed sheet as claimed in claim 1 or 2, the method comprising: a hot-rolling step of hot-rolling a steel material having the composition to obtain a hot-rolled sheet; and a hot-rolled sheet annealing step of annealing the hot-rolled sheet; wherein, in the hot-rolled sheet annealing step, while heating a central portion Xc of the hot-rolled sheet width from room temperature to a holding temperature _T1 and holding the temperature, a steel sheet position Xe located 10 mm from the outermost portion of the sheet width in the width direction of the hot-rolled sheet is heated from room temperature to a maximum temperature _T2 lower than the holding temperature _T1 ; The temperature increase rate Vc of the plate width center portion Xc is set to be greater than the temperature increase rate Ve of the steel plate position Xe by 1.0°C/second or more. A method for manufacturing a hot-rolled annealed sheet as described in claim 3, wherein, in the hot-rolled sheet annealing step, at least one of the following (1) to (4) is satisfied: (1) the holding temperature _T1 of the central portion Xc of the sheet width of the hot-rolled sheet is 900°C or higher; (2) the holding time _t1 of the central portion Xc of the sheet width of the hot-rolled sheet at the holding temperature _T1 is in the range of 2 seconds to 120 seconds; (3) the maximum temperature _T2 at the steel sheet position Xe is in the range of 750°C to 1000°C; and (4) the time _t2 during which the temperature is above the maximum temperature _T2-50 °C is in the range of 5 seconds to 20 seconds. The method for manufacturing a hot-rolled annealed sheet as described in claim 3, wherein, when the hot-rolled sheet annealing step is performed on a hot-rolled sheet having a sheet width W in the range of 900 mm to 1100 mm, a heating suppression zone is provided in a range from a distance of 20 mm or more from the outermost edge of the sheet in the width direction to a distance of 0.250×W or less from the outermost edge of the sheet in the width direction. The method for manufacturing a hot-rolled annealed sheet as described in claim 4, wherein, when the hot-rolled sheet annealing step is performed on a hot-rolled sheet having a sheet width W in the range of 900 mm to 1100 mm, a heating suppression zone is provided in a range from a distance of 20 mm or more from the outermost edge of the sheet in the width direction to a distance of 0.250×W or less from the outermost edge of the sheet in the width direction. A method for manufacturing a non-oriented electromagnetic steel sheet comprises: Cold-rolling the hot-rolled annealed sheet according to claim 1 or 2 to obtain a cold-rolled sheet, and performing finish annealing on the cold-rolled sheet to obtain a cold-rolled annealed sheet.