Method for manufacturing non-oriented electromagnetic steel sheet
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-01-27
- Publication Date
- 2026-08-13
Smart Images
Figure JP2026002622_13082026_PF_FP_ABST
Abstract
Description
Method for manufacturing non-oriented electromagnetic steel sheet
[0001] The present invention relates to a method for manufacturing a non-oriented electromagnetic steel sheet having a high magnetic flux density.
[0002] In recent years, due to the increasing environmental awareness, energy conservation has been promoted, and in the field of electrical equipment, higher efficiency and miniaturization have been actively pursued. Therefore, for non-oriented electromagnetic steel sheets widely used as core materials for electronic devices and automotive main engines, higher magnetic flux density and lower iron loss are required.
[0003] As a method for improving the magnetic flux density of non-oriented electromagnetic steel sheets, improving the grain structure of the product sheet can be mentioned. Specifically, it is effective to reduce the {111} orientation grains or increase the {100} orientation grains and {110} orientation grains. Therefore, in the manufacture of non-oriented electromagnetic steel sheets, conventionally, increasing the crystal grain size before cold rolling or optimizing the cold rolling reduction rate to improve the grain structure has been carried out.
[0004] As another method for controlling the grain structure, a method of increasing the heating rate of recrystallization annealing can be mentioned. For example, in Patent Document 1, a technique has been proposed to improve the grain structure and increase the magnetic flux density by increasing the heating rate of recrystallization annealing, that is, finish annealing. In addition, in Patent Document 2, rapid heating is performed in the temperature range of 630 to 700 °C, which is the region where recrystallization progresses, and holding treatment is performed in the temperature range of 250 to 630 °C until reaching the said temperature region to improve the structure and achieve an increase in magnetic flux density and a reduction in iron loss.
[0005] Japanese Patent Laid-Open No. 02-011728, Japanese Patent Laid-Open No. 2016-199787
[0006] However, in the technique described in Patent Document 1, when induction heating is used as the heating means for finish annealing, there is a problem that the effect of improving the magnetic flux density cannot be stably obtained.
[0007] In addition, the technique described in Patent Document 2 performs multiple induction heatings from room temperature to 740 °C for finish annealing and determines the heating rate of rapid heating up to 700 °C, but does not particularly consider the heating rate after rapid heating.
[0008] Depending on the type of steel, the recrystallization temperature range may overlap with the maximum heating temperature of induction heating, which is around 700°C. In such cases, depending on the heating rate of the steel sheet around the recrystallization temperature range, it becomes problematic to increase the number of grains with {111} orientation, which is unfavorable for improving magnetic flux density.
[0009] This invention has been made in view of these circumstances, and aims to propose a method for manufacturing non-oriented electrical steel sheets that can obtain a high magnetic flux density by controlling the heating pattern in the recrystallization temperature range during the heating process of finish annealing.
[0010] The first method for manufacturing a non-oriented electrical steel sheet according to the present invention, which advantageously solves the above problems, is a method for manufacturing a non-oriented electrical steel sheet containing 2.5% by mass or more of Si, characterized in that a steel material is hot-rolled to make a hot-rolled steel sheet, the hot-rolled steel sheet is annealed, or the hot-rolled steel sheet is cold-rolled once or two or more times with intermediate annealing in between to make a cold-rolled steel sheet, and when finishing annealing is performed on the cold-rolled steel sheet, in the heating process of the finishing annealing, the cold-rolled steel sheet is heated at an average heating rate of 150 to 250°C / s from room temperature to a rapid heating stop temperature in the range of 500°C or higher but below the recrystallization start temperature, thereafter a holding treatment is performed for a holding time in the range of 0.5 to 6 s, and after the holding treatment, the cold-rolled steel sheet is heated at an average heating rate of 20°C / s or more to a maximum attainable temperature in the range of 800 to 1100°C.
[0011] A second method for manufacturing non-oriented electrical steel sheets according to the present invention, which advantageously solves the above problems, is a method for manufacturing non-oriented electrical steel sheets containing 2.5% by mass or more of Si, characterized in that a steel material is hot-rolled to make a hot-rolled steel sheet, the hot-rolled steel sheet is annealed, or the hot-rolled steel sheet is cold-rolled once or two or more times with intermediate annealing in between to make a cold-rolled steel sheet, and when finishing annealing is performed on the cold-rolled steel sheet, in the heating process of the finishing annealing, the cold-rolled steel sheet is heated from room temperature to a rapid heating stop temperature above the recrystallization start temperature at an average heating rate of 150 to 250°C / s, thereafter a holding treatment is performed for a holding time in the range of 0.5 to 6 s, and after the holding treatment, the cold-rolled steel sheet is heated to a maximum attainable temperature in the range of 800 to 1100°C at an average heating rate of 50°C / s or more.
[0012] Furthermore, in the first and second methods for manufacturing non-oriented electrical steel sheets according to the present invention, a more preferable solution is to perform induction heating from room temperature to the rapid heating stop temperature during the finish annealing, and then perform radiant heating to the maximum temperature achieved after the holding treatment.
[0013] According to the present invention, a non-oriented electrical steel sheet with a high magnetic flux density can be obtained even when induction heating is used as the heating means.
[0014] This is a schematic diagram of an annealing furnace used in a method for manufacturing non-oriented electrical steel sheets according to one embodiment of the present invention. This is a graph showing the temperature patterns for taking samples for observation of the cross-section of the steel sheet at each temperature of finish annealing. These are microstructure observation images of the cross-section of the steel sheet at each temperature of finish annealing. This is a graph showing the relationship between the steel sheet temperature at the exit of the induction heating furnace and the magnetic flux density during finish annealing. (a1) and (b1) are graphs showing the temperature patterns for finish annealing steel sheets with different Si content, and (a2) and (b2) are graphs showing the effect of that temperature pattern on the magnetic flux density of the non-oriented electrical steel sheet. (a) and (b) are graphs showing the effect of the heating rate in the range of 680 to 780°C on the magnetic flux density when performing finish annealing on steel sheets with different Si content. This graph shows the effect of the rapid heating stop temperature and the heating rate after rapid heating stop on the magnetic flux density, where (a) to (d) represent the cases where the rapid heating stop temperature is 750°C, 700°C, 650°C, and 600°C, respectively.
[0015] The embodiments of the present invention will be described in detail below. Note that the drawings are schematic and may differ from actual examples. Furthermore, the following embodiments are illustrative examples of devices and methods for realizing the technical concept of the present invention, and do not limit the configuration to those described below. In other words, the technical concept of the present invention can be modified in various ways within the technical scope described in the claims.
[0016] Figure 1 is a schematic diagram of an annealing apparatus suitable for use in a method for manufacturing non-oriented electrical steel sheets according to one embodiment of the present invention. In Figure 1, reference numeral 1 denotes a steel sheet. Reference numeral 2 denotes an induction heating furnace. Reference numeral 3 denotes a radiant heating furnace. The radiant heating furnace 3 consists of a heating zone, a soaking zone, and a cooling zone. A fixed interval 4 is provided between the induction heating furnace 2 and the radiant heating furnace 3.
[0017] Steel sheet 1 is a cold-rolled steel sheet. In this embodiment, a steel material containing 2.5% by mass or more of Si is hot-rolled to produce a hot-rolled steel sheet, and then the hot-rolled steel sheet is annealed, or the hot-rolled steel sheet is cold-rolled once or twice or more with intermediate annealing in between to prepare a cold-rolled steel sheet. A non-oriented electrical steel sheet is manufactured by finishing annealing the cold-rolled steel sheet.
[0018] The induction heating furnace 2 can be, for example, a solenoid-type induction heating furnace, and it heats the steel plate 1 from room temperature to the induction heating end temperature at an average heating rate in the range of 150 to 250°C / s. Induction heating by the induction heating furnace can heat the steel plate to the induction heating limit temperature below the Curie point.
[0019] In the holding section 4, a holding treatment is performed for a period of 0.5 to 6 seconds from the end of induction heating to the start of radiant heating. The holding treatment refers to a process of maintaining the steel plate temperature within a range of ±5°C from the induction heating end temperature. There are no specific requirements for the equipment used for the holding treatment. As long as the temperature stays within the above temperature range, no equipment is required, or the steel plate temperature may be kept uniform using electric heaters or the like.
[0020] The radiant heating furnace 3 can utilize radiant heat from radiant tubes or electric heaters. In this embodiment, after a holding treatment in the heating zone, the furnace is heated to a maximum temperature in the range of 800 to 1100°C at an average heating rate of 20°C / s or more. Preferably, the furnace is heated at an average heating rate of 50°C / s or more.
[0021] (Experiment 1) The temperature history of finish annealing during the manufacturing of non-oriented electrical steel sheets was simulated, and the microstructure changes of the steel sheets were observed. Figure 2 shows the temperature history of a to g. The dashed line shows the temperature history of the steel sheets during finish annealing. The steel sheets were heated using an induction heating device up to 700°C, and a radiant heating device was used to heat the steel sheets above 700°C. Samples a to d, f, and g were heated to a predetermined temperature, held for 0.4 s to stabilize the steel sheet temperature, and then cooled. Sample e was heated to 700°C, held at 700°C for 1.8 s, and then cooled.
[0022] Figure 3 shows microstructural observation images of steel plate cross-sections of samples a to g. Samples a to c were heated to below 650°C, and grain growth, i.e., recrystallization, had not yet begun, so the impact on magnetic properties is considered to be small. Recrystallized grains are observed in samples d to g.
[0023] (Experiment 2) Figure 4 shows the relationship between the steel sheet temperature at the induction heating furnace exit and the magnetic flux density for non-oriented electrical steel sheets produced in the process. In Figure 4, the horizontal axis represents the steel sheet temperature at the induction heating furnace exit, and the vertical axis represents the magnetic flux density B50. The magnetic flux density B50 represents the value (T) of the magnetic flux density when the magnetic field strength is 5000 A / m. For the measurement of the magnetic flux density B50, an Epstein test with a 15 cm frame was used in accordance with JIS C 2550-1:2011. The test specimen size was 30 mm × 180 mm × plate thickness, with two specimens in the L direction and two in the C direction. The N value accompanying the plot is the number of coils measured, the average value is plotted, and the variation of 3σ is shown by the whiskers. The plot "◇" represents the lead end (LE) of the coil, and the plot "〇" represents the tail end (TE) of the coil. A decrease in magnetic flux density is observed when the steel plate temperature at the exit of the induction heating furnace is around 700°C, which is within the recrystallization temperature range. From the results of Experiment 1, it was found that recrystallization during the holding treatment after induction heating is influencing the decrease in magnetic flux density.
[0024] (Experiment 3) Therefore, we considered changing the stop temperature of rapid heating by induction heating, hereinafter referred to as the rapid heating stop temperature. Figures 5(a1) and 5(b1) show the heat patterns of finish annealing of steel types with different Si content. Figure 5(a1) shows the case of a non-oriented electrical steel sheet with a thickness t = 0.3 mm and a Si content of 3.0 mass% or more. Figure 5(b1) shows the case of a non-oriented electrical steel sheet with a thickness t = 0.35 mm and a Si content of 2.5 mass% or more. Pattern X shows the case where induction heating is performed up to the induction heating limit temperature of 700°C. In Pattern Y, the stop temperature of induction heating, i.e., the rapid heating stop temperature, is set to 500°C, and the radiant heating after the holding treatment is set to reach the highest temperature and processing time of Pattern X, so that the subsequent heat pattern is the same as Pattern X.
[0025] For each steel type, the magnetic flux density of non-oriented electrical steel sheets manufactured using each heat pattern was measured and is shown in Figures 5(a2) and 5(b2), respectively. The measurement of magnetic flux density B50 was performed in the same manner as in Experiment 2. Pattern Y, in which the rapid heating stop temperature was set below the recrystallization start temperature, yielded a higher magnetic flux density than pattern X, in which the rapid heating stop temperature was in the recrystallization temperature range.
[0026] (Experiment 4) Next, the effect of the time the steel sheet stays in the recrystallization temperature range was investigated. Figures 6(a) and (b) show the relationship between the average heating rate (°C / s) from 680 to 780°C and the magnetic flux density for steel types with different Si content. Figure 6(a) shows the case of a non-oriented electrical steel sheet with a thickness t = 0.3 mm and a Si content of 3.0 mass% or more. Figure 6(b) shows the case of a non-oriented electrical steel sheet with a thickness t = 0.35 mm and a Si content of 2.5 mass% or more. By increasing the average heating rate from 680 to 780°C from about 18°C / s to 42 to 56°C / s, an improvement of 0.003 to 0.007 T in the magnetic flux density B50 was obtained.
[0027] (Experiment 5) Based on the above results, the magnetic flux density was measured for non-oriented electrical steel sheets with a thickness t = 0.3 mm and a Si content of 3.0 mass% or more, by varying the rapid heating stop temperature and subsequent heating rate during finish annealing. The rapid heating stop temperatures were 600°C, 650°C, 700°C, and 750°C, and the holding treatment was 1 s. The subsequent heating rates were 20°C / s, 30°C / s, and 50°C / s, which were average heating rates up to 800°C.
[0028] The results are shown in Figures 7(a) to 7(d). The hatched areas in each figure indicate the standard magnetic flux density range for non-oriented electrical steel sheets. When the rapid heating stop temperature was 700°C and 750°C, the magnetic flux density B50 was inferior when the subsequent heating rate was 30°C / s or less. Even in those cases, when the heating rate after rapid heating was 50°C / s, a magnetic flux density B50 equivalent to or superior to the standard was obtained. When the rapid heating stop temperature was 650°C or less, below the recrystallization start temperature, a magnetic flux density B50 equivalent to or superior to the standard was obtained when the subsequent heating rate was 20°C / s or more.
[0029] (Experiment 6) A non-oriented electrical steel sheet with a thickness t = 0.35 mm and a Si content of 2.5 mass% or more was subjected to the same test as in Experiment 5, and the results are shown in Figure 8. In Figure 8, the horizontal axis represents the heating rate of the steel sheet after rapid heating cessation, and the vertical axis represents the rapid heating cessation temperature. In Figure 8, the symbol [○] indicates that the magnetic flux density is superior to the standard, the symbol "□" indicates that the magnetic flux density is equivalent to the standard, and the symbol "×" indicates that the magnetic flux density is inferior to the standard. Results showing a magnetic flux density equivalent to or better than the standard were obtained in the hatched area of Figure 8.
[0030] <First Embodiment> The method for manufacturing non-oriented electrical steel sheets according to the first embodiment, obtained as a result of the above, involves hot-rolling a steel material containing 2.5% by mass or more of Si to obtain a hot-rolled steel sheet. After annealing the hot-rolled steel sheet, or directly cold-rolling the hot-rolled steel sheet once or two or more times with intermediate annealing in between, to obtain a cold-rolled steel sheet. Then, finish annealing is performed on the cold-rolled steel sheet. During the heating process of the finish annealing, the cold-rolled steel sheet is heated at an average heating rate (first heating rate) of 150 to 250°C / s from room temperature to a rapid heating stop temperature in the range of 500°C or higher but below the recrystallization start temperature. After that, a holding treatment is performed for a holding time in the range of 0.5 to 6 s. Then, after the holding treatment, the cold-rolled steel sheet is heated at an average heating rate (second heating rate) of 20°C / s or more to a maximum attainable temperature in the range of 800 to 1100°C.
[0031] In the first embodiment, the rapid heating stop temperature is preferably 550°C or higher, and more preferably 600°C or higher. In the first embodiment, there is no upper limit to the second heating rate to the maximum temperature reached after the holding treatment, but since making the second heating rate excessively high would result in excessive capital investment, it is preferable to set the upper limit to 100°C / s. In the first embodiment, it is preferable to set the average heating rate in the recrystallization temperature range to 20°C / s or higher.
[0032] <Second Embodiment> The method for manufacturing non-oriented electrical steel sheets according to the second embodiment, obtained as a result of the above, involves hot rolling a steel material containing 2.5% by mass or more of Si to obtain a hot-rolled steel sheet. After annealing the hot-rolled steel sheet, or directly cold-rolling the hot-rolled steel sheet once or two or more times with intermediate annealing in between, to obtain a cold-rolled steel sheet. Then, finish annealing is performed on the cold-rolled steel sheet. During the heating process of the finish annealing, the cold-rolled steel sheet is heated at an average heating rate (first heating rate) of 150 to 250°C / s from room temperature to a rapid heating stop temperature above the recrystallization start temperature. After that, a holding treatment is performed for a holding time in the range of 0.5 to 6 s. Then, after the holding treatment, the cold-rolled steel sheet is heated at an average heating rate (second heating rate) of 50°C / s or more to a maximum attainable temperature in the range of 800 to 1100°C.
[0033] In the second embodiment, the rapid heating stop temperature is preferably below the induction heating limit temperature. In the second embodiment, there is no upper limit on the second heating rate to the maximum temperature reached after the holding treatment, but since making the second heating rate excessively high would result in excessive capital investment, it is preferable to set the upper limit to 100°C / s. In the second embodiment, it is preferable to set the average heating rate (second heating rate) in at least the recrystallization temperature range to 50°C / s or higher.
[0034] In the finish annealing according to the above embodiment, induction heating is preferably performed from room temperature to the rapid heating stop temperature. Furthermore, radiant heating is preferably performed to the maximum temperature reached after the holding treatment.
[0035] Next, the component composition of a steel material suitable for manufacturing the non-oriented electrical steel sheet of the above embodiment will be described. In the following chemical compositions, unless otherwise specified, "mass%" will be simply written as "%".
[0036] Si: 2.5% or more. Si is an effective element for increasing the resistivity of steel and reducing iron loss, and therefore requires the addition of 2.5% or more. On the other hand, if the Si content exceeds 8.0%, rolling may become difficult, so it is preferable to set the upper limit at 8.0%. From the viewpoint of manufacturability, a Si content of 4.0% or less is more preferable. A Si content of 3.0% or more is preferable.
[0037] C: 0.0050% or less. C may cause magnetic aging and form carbides, potentially worsening iron loss characteristics. A C content of 0.0050% or less is preferred. More preferably, it is 0.0040% or less. There is no specific lower limit, but from the viewpoint of suppressing decarburization costs, it is preferable to set it at around 0.0001%.
[0038] Mn: 0.03 to 3.0%. In addition to fixing sulfur and preventing hot embrittlement, Mn has the effect of increasing the resistivity of steel and reducing iron loss. To obtain the above effects, an addition of 0.03% or more is preferable. However, if it exceeds 3.0%, the magnetic flux density may decrease. Therefore, the Mn content is preferably in the range of 0.03 to 3.0%. More preferably, the Mn content is in the range of 0.05 to 1.0%.
[0039] P: 0.1% or less. P is an element used to adjust the strength of steel because of its high solid solution strengthening ability. However, if it exceeds 0.1%, the steel may become brittle, making rolling difficult. The upper limit of the P content is preferably 0.1 mass%. More preferably, the P content is 0.08% or less. There is no specific lower limit, but from the viewpoint of reducing the P removal load, it is preferable to set it to around 0.001%.
[0040] Al: 3.0% or less. Similar to Si, Al has the effect of increasing the specific resistance of steel and reducing iron loss. However, if it exceeds 3.0%, it may become difficult to roll. Therefore, the upper limit of the Al content is preferably set to about 3.0%. However, when the Al content is in the range of 0.01 - 0.1%, fine AlN precipitates and the iron loss increases. Therefore, it is more preferably 0.01% or less or in the range of 0.1 - 2.0%. Note that when Al is reduced, the grain structure is improved and the magnetic flux density is increased. Therefore, when desiring to obtain the above effects, it is even more preferable to set Al to 0.01% or less.
[0041] S, N, and O: Each 0.005% or less. S, N, and O (oxygen) are all harmful elements that form fine precipitates and increase iron loss. Especially when the content exceeds 0.005%, the adverse effects become significant. Therefore, S, N, and O are preferably limited to 0.005% or less each. More preferably, each is 0.003% or less.
[0042] The steel material for non-oriented electrical steel sheets according to the present embodiment may contain Ni, Cr, Ti, Nb, As, Sn, Sb, Ca, Mg, and REM in a total amount of 1% or less in addition to the above. Note that the balance other than the above component composition in the steel material for non-oriented electrical steel sheets according to the present embodiment is Fe and inevitable impurities.
[0043] Next, the manufacturing method of the non-oriented electrical steel sheet according to the present embodiment will be described. The non-oriented electrical steel sheet according to the present embodiment is refined in a converter or melted in an electric furnace to obtain molten steel, and the molten steel is adjusted to the above component composition through a conventional refining process of secondary refining in a degassing facility or the like. The molten steel is made into a steel material such as a steel slab by a continuous casting method or the like. The steel material is hot-rolled to obtain a hot-rolled steel sheet. After subjecting the hot-rolled steel sheet to hot-rolled sheet annealing as necessary, pickling is performed, and cold rolling is performed one or two or more times with intermediate annealing interposed to obtain a cold-rolled steel sheet. Then, finish annealing is performed on the cold-rolled steel sheet.
[0044] Here, the conditions for the hot rolling are not particularly defined. However, from the perspective of enhancing magnetic properties, the finishing rolling temperature is preferably in the range of 700 to 900 °C, and the coiling temperature is preferably in the range of 600 to 800 °C. Further, the annealing of the hot-rolled sheet after hot rolling may be performed as necessary.
[0045] Next, the hot-rolled steel sheet after the hot rolling or after the annealing of the hot-rolled sheet is made into a cold-rolled steel sheet with the final plate thickness by one or more cold rollings including an intermediate annealing. At this time, it is preferable to control the ferrite grain size of the steel sheet before the final cold rolling to 50 μm or less. Here, the final cold rolling means the cold rolling when the cold rolling is performed once, and in the case of a plurality of cold rollings, it means the cold rolling to the final plate thickness.
[0046] Here, the control of the ferrite grain size can be performed by adjusting the finishing rolling temperature in the hot rolling, the coiling temperature (self-annealing temperature), the annealing temperature of the hot-rolled sheet, the intermediate annealing temperature, etc. From the perspective of preventing ridging, the recrystallization rate of the steel sheet structure before the final cold rolling is preferably 80% or more.
[0047] The cold-rolled sheet with the final plate thickness is subjected to finish annealing to make it a non-oriented electrical steel sheet. The temperature rising process in the finish annealing adopts the first embodiment or the second embodiment.
[0048] The annealing atmosphere in the finish annealing is preferably a reducing atmosphere. For example, it is preferably a hydrogen-nitrogen mixed atmosphere with P Ｈ２Ｏ / P Ｈ２ of 0.1 or less. Next, the steel sheet after the finish annealing is coated with an insulating film as necessary to make it a product sheet. The insulating film can use known organic, inorganic, or organic-inorganic hybrid coatings according to the required characteristics. For example, in order to ensure good punching properties, it is preferable to apply an organic coating containing a resin, and in the case of emphasizing weldability, it is preferable to apply a semi-organic or inorganic coating.
[0049] Steel slabs with the component composition listed in Table 1 were prepared. After heating the steel slabs, they were hot-rolled to obtain 2.0 mm thick hot-rolled steel sheets. After annealing the hot-rolled sheets at 950°C and removing the scale from the surface, they were cold-rolled to a final thickness of 0.20 mm in one cold-rolling pass. Next, finish annealing was performed under the conditions in Table 2 to obtain non-oriented electrical steel sheets. The first heating rate in Table 2 is the average heating rate from room temperature to the rapid heating stop temperature. A holding treatment was performed at the rapid heating stop temperature for the holding time listed in Table 2. The second heating rate in Table 2 is the average heating rate from the end of the holding treatment to the maximum temperature of 1050°C.
[0050]
[0051]
[0052] 1. Steel plate 2. Induction heating furnace 3. Radiation heating furnace 4. Holding section FD (direction of movement of the steel plate)
Claims
1. A method for manufacturing a non-oriented electrical steel sheet containing 2.5% by mass or more of Si, comprising: hot rolling a steel material to obtain a hot-rolled steel sheet; annealing the hot-rolled steel sheet, or cold rolling the hot-rolled steel sheet once or two or more times with intermediate annealing in between to obtain a cold-rolled steel sheet; and, in the process of finishing the cold-rolled steel sheet, during the heating process of the finishing annealing, the cold-rolled steel sheet is heated at an average heating rate of 150 to 250°C / s from room temperature to a rapid heating stop temperature in the range of 500°C or higher but below the recrystallization start temperature; thereafter, a holding treatment is performed for a holding time in the range of 0.5 to 6 s; and after the holding treatment, the cold-rolled steel sheet is heated at an average heating rate of 20°C / s or more to a maximum attainable temperature in the range of 800 to 1100°C.
2. A method for manufacturing a non-oriented electrical steel sheet containing 2.5% by mass or more of Si, comprising: hot rolling a steel material to obtain a hot-rolled steel sheet; annealing the hot-rolled steel sheet, or cold rolling the hot-rolled steel sheet once or two or more times with intermediate annealing in between to obtain a cold-rolled steel sheet; and, in the process of finishing the cold-rolled steel sheet, during the heating process of the finishing annealing, the cold-rolled steel sheet is heated from room temperature to a rapid heating stop temperature above the recrystallization start temperature at an average heating rate of 150 to 250°C / s; thereafter, a holding treatment is performed for a holding time in the range of 0.5 to 6 s; and after the holding treatment, the cold-rolled steel sheet is heated to a maximum attainable temperature in the range of 800 to 1100°C at an average heating rate of 50°C / s or more.
3. The method for manufacturing a non-oriented electrical steel sheet according to claim 1 or 2, wherein in the finish annealing, induction heating is performed from room temperature to the rapid heating stop temperature, and after the holding treatment, radiant heating is performed to the maximum temperature reached.