Hot-rolled annealed sheet for non-oriented electromagnetic steel sheet, method for manufacturing same, and method for manufacturing non-oriented electromagnetic steel sheet

Abstract

According to the present invention, a steel slab containing a predetermined amount of C, Si, Mn, P, S, Al, N, O, Sn, and Sb is heated under a predetermined condition, hot rolled, hot annealed, shot blasted and pickled, or the steel slab is heated under a predetermined condition, hot rolled, hot annealed, brush ground and pickled such that the average grain size in a cross section in the rolling direction of a steel sheet after the pickling is 40-250 μm and the integrated intensity of Fe-Al-based oxides in the surface layer of the steel sheet measured by X-ray diffraction is 200 cps∙degree or less, thereby obtaining a hot-rolled annealed sheet for a non-oriented electromagnetic steel sheet, which enables the prevention of sheet breakage during cold rolling and exhibits excellent magnetic properties after cold-rolled sheet annealing. In addition, a non-oriented electromagnetic steel sheet is manufactured using the hot-rolled annealed sheet.

Description

Hot-rolled annealed sheet for non-oriented electrical steel sheet, its manufacturing method, and manufacturing method for non-oriented electrical steel sheet

[0001] The present invention relates to a hot-rolled and annealed sheet for use in a non-oriented electrical steel sheet, which has excellent resistance to fracture during cold rolling, a method for manufacturing the same, and a method for manufacturing a non-oriented electrical steel sheet using the hot-rolled and annealed sheet.

[0002] In recent years, the rise in awareness of environmental issues has led to a decline in CO emissions. ２ With the increasing need for reductions in power consumption and energy conservation, there is a strong demand for higher efficiency in electrical equipment, including electric vehicles. Therefore, there is a strong demand for improved iron loss properties in non-oriented electrical steel sheets, which are widely used as iron core materials for motors used in electrical equipment. To address this, iron loss has been improved by adding large amounts of elements that increase resistivity, such as Si and Al, or by reducing the sheet thickness. However, adding large amounts of Si and Al or reducing the final sheet thickness increases the manufacturing load during cold rolling, so in addition to improving magnetic properties, it has become important to prevent problems such as steel sheet fracture during cold rolling.

[0003] To solve this problem, techniques have been proposed, such as controlling the annealing temperature of the hot-rolled sheet to improve toughness and thereby suppressing sheet breakage during cold rolling.

[0004] For example, Patent Document 1 discloses a non-oriented electrical steel sheet containing, in mass %, C: 0.0010 to 0.0050%, Si: 2.5 to 4.0%, Al: 0.2 to 2.0%, Mn: 0.05 to 2.0%, P: 0.005 to 0.15%, S: 0.0001 to 0.0030%, Ti: 0.0005 to 0.0030%, and N: 0.0010 to 0.0030%, with the balance being Fe and unavoidable impurities, with the base steel having a thickness of 0.10 mm or more and 0.35 mm or less, and with the Al concentration in the depth direction from the surface of the base steel satisfying the relationship shown in Formula (1) below. According to this, it is explained that if the soaking temperature during hot-rolled sheet annealing exceeds 1100°C or the soaking time exceeds 300 seconds, there is a possibility that the base steel will fracture during subsequent cold rolling. 0.1≦Al(x≦2 μm) / Al(x=10 μm)<1.0 (1) Here, in the above formula (1), x is the depth [μm] from the surface of the base steel, Al(x≦2 μm) is the average Al concentration from the surface of the base steel to a depth of 2 μm, and Al(x=10 μm) is the Al concentration at a depth of 10 μm.

[0005] Japanese Patent Application Laid-Open No. 2018-021241

[0006] However, the prior art disclosed in the above patent document has the following problems.

[0007] According to the results of the inventors' investigations, it was found that the occurrence of fractures cannot necessarily be suppressed by only controlling the annealing conditions of the hot-rolled sheet as described in the above Patent Document 1, and that it is difficult to achieve both fracture resistance in cold rolling and good magnetic properties after annealing of the cold-rolled sheet.

[0008] The present invention has been made in view of the above problems, and aims to provide a hot-rolled annealed sheet for non-oriented electrical steel sheet that prevents breakage during cold rolling after hot-rolled sheet annealing and has excellent magnetic properties after cold-rolled sheet annealing, and to propose a method for manufacturing the same and a method for manufacturing non-oriented electrical steel sheet using the hot-rolled annealed sheet.

[0009] The hot-rolled annealed sheet for non-oriented electrical steel sheet according to the present invention, which advantageously solves the above problems, is configured as follows: [1] A hot-rolled annealed sheet for non-oriented electrical steel sheet, having a chemical composition containing, by mass%, 0.0050% or less C, 2.0 to 5.0% Si, 0.2 to 2.0% Mn, 0.030% or less P, 0.0050% or less S, 0.25 to 2.50% Al, 0.0050% or less N, 0.0050% or less O, 0.0050% or less Sn and / or Sb in total, and the balance consisting of Fe and unavoidable impurities, wherein the average crystal grain size in the cross section in the rolling direction of the steel sheet is 40 to 250 μm, and the integrated intensity of Fe—Al-based oxides in the surface layer of the steel sheet, as measured by X-ray diffraction, is 200 cps degrees or less. [2] The hot-rolled annealed sheet for non-oriented electrical steel sheet according to the above item [1], further containing, in mass %, one or more elements selected from the following groups A to D in addition to the above-mentioned chemical composition: Group A: 0.0010 to 0.0080% of one or more elements selected from Ca, Mg, and REM; Group B: 0.01 to 0.60% of one or more elements selected from Cr, Mo, Cu, and Ni in total; Group C: 0.0005 to 0.0030% of one or more elements selected from Ti, Nb, and V in total; Group D: B: 0.0001 to 0.0020% [3] The hot-rolled annealed sheet for non-oriented electrical steel sheet according to the above item [1] or [2], further containing, in mass %, one or more elements selected from the following groups E to J in addition to the above-mentioned chemical composition: Group E: Zn: 0.001 to 0.010% Group F: One or more elements selected from Zr, Ta, W, and Se, in total, 0.001 to 0.010% Group G: One or more elements selected from Ga and Ge, in total, 0.0001 to 0.0200% Group H: One or more elements selected from Pb and Bi, in total, 0.00005 to 0.0020% Group I: Co: 0.001 to 0.100% Group J: As: 0.0005 to 0.020%

[0010] The method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to the present invention, which advantageously solves the above-mentioned problems, is configured as follows: [4] A hot rolling step of heating and hot-rolling a steel slab having a chemical composition containing, by mass%, C: 0.0050% or less, Si: 2.0 to 5.0%, Mn: 0.2 to 2.0%, P: 0.030% or less, S: 0.0050% or less, Al: 0.25 to 2.50%, N: 0.0050% or less, O: 0.0050% or less, Sn and / or Sb: 0.01 to 0.20% in total, with the balance being Fe and unavoidable impurities, to produce a hot-rolled steel sheet; the hot-rolled sheet annealing step of subjecting the hot-rolled annealed sheet to shot blasting, and the shot-blasted hot-rolled annealed sheet to pickling; wherein in the hot-rolling step, the heating temperature of the steel slab is 1150°C or less, the finish rolling temperature is 960°C or less, and the coiling temperature is 700°C or less; in the hot-rolled sheet annealing step, the annealing temperature is 800°C or more and 1100°C or less; and in the shot blasting step, the shot density is 10 to 40 kg / m ２and in the pickling step, the shot-blasted steel sheet is pickled with a hydrochloric acid concentration of 5% or more, a pickling temperature of 70°C or more, and a pickling time of 10 seconds or more and 120 seconds or less. [5] The method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to the above item [4], wherein the steel slab further contains, in mass %, one or more elements selected from the following groups A to D in addition to the above chemical composition: [6] A method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to the above [4] or [5], characterized in that the steel slab further contains, in mass %, one or more elements selected from the following groups E to J in addition to the above chemical composition: Group A: one or more elements selected from Ca, Mg, and REM, in a total of 0.0010 to 0.0080% Group B: one or more elements selected from Cr, Mo, Cu, and Ni, in a total of 0.01 to 0.60% Group C: one or more elements selected from Ti, Nb, and V, in a total of 0.0005 to 0.0030% Group D: B: 0.0001 to 0.0020%. Group E: Zn: 0.001 to 0.010% Group F: One or more elements selected from Zr, Ta, W, and Se, totaling 0.001 to 0.010% Group G: One or more elements selected from Ga and Ge, totaling 0.0001 to 0.0200% Group H: One or more elements selected from Pb and Bi, totaling 0.00005 to 0.0020% Group I: Co: 0.001 to 0.100% Group J: As: 0.0005 to 0.020% [7] A method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet in any one of [4] to [6] above, characterized in that the hot-rolled steel sheet is subjected to rolling and / or tensile bending at an elongation rate of 0.1 to 10.0% before annealing the hot-rolled steel sheet. [8] In any one of the above [4] to [7], the method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet is characterized in that, after the pickling step, brush grinding is performed on the front and back surfaces of the pickled steel sheet.

[0011] The method for producing a non-oriented electrical steel sheet according to the present invention, which advantageously solves the above problems, is configured as follows: [9] A method for producing a non-oriented electrical steel sheet, comprising: subjecting a hot-rolled annealed sheet obtained in any one of the above [4] to [8] to one cold rolling or two or more cold rolling steps including intermediate annealing to obtain a cold-rolled sheet having a final thickness; and annealing the cold-rolled sheet at a soaking temperature of 700 to 1100°C to obtain a cold-rolled annealed sheet.

[0012] Another method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to the present invention, which advantageously solves the above-mentioned problems, is configured as follows:

[10] A hot rolling step of heating and hot-rolling a steel slab having a chemical composition containing, by mass%, C: 0.0050% or less, Si: 2.0 to 5.0%, Mn: 0.2 to 2.0%, P: 0.030% or less, S: 0.0050% or less, Al: 0.25 to 2.50%, N: 0.0050% or less, O: 0.0050% or less, Sn and / or Sb: 0.01 to 0.20% in total, with the balance being Fe and unavoidable impurities;

[11] This is a manufacturing method of a hot-rolled annealed sheet for non-oriented electrical steel sheet, comprising a brush grinding step of brush-grinding an annealed sheet, and a pickling step of pickling the brush-ground hot-rolled annealed sheet, wherein in the hot rolling step, the heating temperature of the steel slab is 1150°C or less, the finish rolling temperature is 960°C or less, and the coiling temperature is 700°C or less, and in the hot-rolled sheet annealing step, the annealing temperature is 800°C or more and 1100°C or less, and in the pickling step, the brush-ground steel sheet is pickled with a hydrochloric acid concentration of 5% or more, a pickling temperature of 70°C or more, and a pickling time of 10 seconds or more and 120 seconds or less.

[11] This is a manufacturing method of a hot-rolled annealed sheet for non-oriented electrical steel sheet in the above

[10] , wherein the steel slab further contains, in mass %, one or more elements selected from the following groups A to D in addition to the above chemical composition.

[12] A method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to the above

[10] or

[11] , wherein the steel slab further contains, in mass %, one or more elements selected from the following groups E to J in addition to the above chemical composition: Group A: one or more elements selected from Ca, Mg, and REM, in a total content of 0.0010 to 0.0080% Group B: one or more elements selected from Cr, Mo, Cu, and Ni, in a total content of 0.01 to 0.60% Group C: one or more elements selected from Ti, Nb, and V, in a total content of 0.0005 to 0.0030% Group D: B: 0.0001 to 0.0020%.

[12] A method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to the above

[10] or

[11] , wherein the steel slab further contains, in mass %, one or more elements selected from the following groups E to J in addition to the above chemical composition:Group E: Zn: 0.001 to 0.010% Group F: One or more elements selected from Zr, Ta, W, and Se, totaling 0.001 to 0.010% Group G: One or more elements selected from Ga and Ge, totaling 0.0001 to 0.0200% Group H: One or more elements selected from Pb and Bi, totaling 0.00005 to 0.0020% Group I: Co: 0.001 to 0.100% Group J: As: 0.0005 to 0.020%

[13] A method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet in any one of

[10] to

[12] above, characterized in that the hot-rolled steel sheet is subjected to rolling and / or tensile bending at an elongation rate of 0.1 to 10.0% before annealing the hot-rolled steel sheet.

[14] In any one of the above

[10] to

[13] , the method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet is characterized in that, after the pickling step, brush grinding is performed on the front and back surfaces of the pickled steel sheet.

[0013] Another method for producing a non-oriented electrical steel sheet according to the present invention that advantageously solves the above problems is configured as follows:

[15] A method for producing a non-oriented electrical steel sheet, comprising: subjecting a hot-rolled and annealed sheet obtained in any one of the above

[10] to

[14] to one cold rolling or two or more cold rolling steps including intermediate annealing to obtain a cold-rolled sheet having a final thickness; and annealing the cold-rolled sheet at a soaking temperature of 700 to 1100°C to obtain a cold-rolled and annealed sheet.

[0014] According to the present invention, it is possible to efficiently manufacture a non-oriented electrical steel sheet having excellent magnetic properties while suppressing breakage of the steel sheet during cold rolling.

[0015] The inventors conducted extensive research into the causes of sheet fracture during cold rolling. As a result, in steel sheets containing large amounts of Si and Al, as in the present invention, not only iron oxides but also Si and Al oxides are formed on the steel sheet surface during hot rolling or hot-rolled sheet annealing. In particular, dense Fe-Al scale is formed near the interface between the base steel and the oxide layer. Because this Fe-Al scale is poorly soluble in acid, if it cannot be completely removed in the pickling process, it accelerates wear of the rolling rolls in cold rolling, making the steel sheet more susceptible to fracture. To solve this problem, the inventors investigated the mechanical and chemical conditions related to scale removal and found appropriate conditions for stably removing scale, including Fe-Al scale, which led to the development of the present invention.

[0016] Hereinafter, a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to this embodiment will be described. First, the chemical composition of the hot-rolled annealed sheet for a non-oriented electrical steel sheet according to this embodiment and the reasons for limiting the composition will be described. In the following description, unless otherwise specified, the notation "%" means "% by mass." <Hot-rolled annealed sheet for a non-oriented electrical steel sheet> The hot-rolled annealed sheet for a non-oriented electrical steel sheet according to this embodiment has a chemical composition containing, by mass%, C: 0.0050% or less, Si: 2.0 to 5.0%, Mn: 0.2 to 2.0%, P: 0.030% or less, S: 0.0050% or less, Al: 0.25 to 2.50%, N: 0.0050% or less, O: 0.0050% or less, Sn and / or Sb: 0.01 to 0.20% in total, and the balance being Fe and unavoidable impurities.

[0017] C: 0.0050% or less C is an element that forms carbides and deteriorates iron loss after finish annealing. C also increases the hardness of the hot-rolled annealed sheet, inducing sheet fracture during cold rolling. For this reason, the C content is set to 0.0050% or less. A preferred C content is 0.0030% or less. There is no particular lower limit for the C content, but from the viewpoint of improving the toughness of the hot-rolled annealed sheet and preventing sheet fracture during cold rolling, it is preferably set to 0.0010% or more.

[0018] Si: 2.0 to 5.0% Si has the effect of increasing the resistivity of steel and reducing iron loss after finish annealing, so the content is set to 2.0% or more. Preferably, it is set to 2.7% or more. On the other hand, if the Si content exceeds 5.0%, the hot-rolled annealed sheet becomes excessively hardened and embrittled, making it prone to fracture during cold rolling, so the upper limit is set to 5.0%. Preferably, it is set to 4.5% or less.

[0019] Mn: 0.2 to 2.0% Like Si, Mn is an element useful for reducing iron loss, and also has the effect of improving the toughness of the base steel and suppressing sheet fracture during cold rolling, so the Mn content is set to 0.2% or more, preferably 0.35% or more. On the other hand, if the Mn content exceeds 2.0%, the hot-rolled annealed sheet becomes excessively hard and prone to fracture during cold rolling, so the Mn content is set to 2.0% or less.

[0020] P: 0.030% or less P has the effect of increasing the strength of steel and can be used to adjust strength. On the other hand, if the P content exceeds 0.030%, the steel becomes embrittled, resulting in a decrease in manufacturability. Therefore, the P content is set to 0.030% or less. From the viewpoint of preventing embrittlement, the P content is preferably 0.015% or less. There is no particular lower limit for the P content, but from the viewpoint of reducing the dephosphorization load, it is preferably set to about 0.004%.

[0021] S: 0.0050% or less S segregates at grain boundaries and embrittles hot-rolled annealed sheets, making the steel sheet more susceptible to fracture during cold rolling. It also forms fine sulfides, which deteriorate the iron loss after finish annealing. Therefore, the upper limit of the S content is set to 0.0050%. A preferred S content is 0.0025% or less. While there is no particular lower limit for the S content, it is preferably set to about 0.001% from the viewpoint of reducing the desulfurization load.

[0022] Al: 0.25 to 2.50% Like Si, Al has the effect of increasing the resistivity of steel sheet and reducing iron loss after finish annealing, so the Al content is set to 0.25% or more. Furthermore, Al forms AlN, which has a pinning effect that reduces the average crystal grain size of the hot-rolled annealed sheet and improves fracture resistance during cold rolling. Therefore, the Al content is preferably 0.50% or more. More preferably, it is 0.70% or more. On the other hand, if the Al content exceeds 2.50%, the amount of Fe-Al-based oxides in the scale generated during hot rolling and hot-rolled sheet annealing increases, and these oxides cannot be completely removed in the pickling process, causing sheet fracture during cold rolling. Therefore, the upper limit of Al is set to 2.50%. It is preferably 2.30% or less.

[0023] N: 0.0050% or less N forms nitrides that may become the starting points for sheet fracture during cold rolling, so the upper limit of the N content is set to 0.0050%. Note that fine nitrides inhibit grain growth and deteriorate iron loss after finish annealing, so the preferred N content is 0.0035% or less.

[0024] O: 0.0050% or less O forms oxides that may become the starting points for sheet fracture during cold rolling, so the upper limit is set to 0.0050%. Furthermore, the formed oxides inhibit the grain growth of ferrite structures and deteriorate the iron loss after finish annealing, so the preferred O content is 0.0025% or less.

[0025] Sn and Sb: 0.01 to 0.20% in total of one or more Sn and Sb have the effect of improving magnetic properties by improving the texture after cold rolling and finish annealing, and also have the effect of suppressing the formation of Fe—Al-based oxides through surface segregation, thereby improving fracture resistance during cold rolling. Therefore, the total content of one or more Sn and Sb is set to 0.01% or more, preferably 0.02% or more. On the other hand, excessive addition not only saturates the effect, but also deteriorates the toughness of the hot-rolled annealed sheet, making the sheet more susceptible to fracture during cold rolling, so the upper limit of the total content of Sn and Sb is set to 0.20%.

[0026] The above are the basic components of the hot-rolled annealed sheet for the non-oriented electrical steel sheet according to this embodiment, but in order to further improve various properties, it is preferable to contain at least one group of components selected from the following groups A to D.

[0027] Group A: 0.0010 to 0.0080% in total of one or more elements selected from Ca, Mg, and REM. Ca, Mg, and REM have the effect of fixing S as sulfides and improving iron loss. For this reason, it is preferable that one or more elements of Ca, Mg, and REM are contained in a total of 0.0010% or more. More preferably, it is 0.0020% or more. On the other hand, if the total content of Ca, Mg, and REM exceeds 0.0080%, excessive inclusions are formed, reducing manufacturability, so the upper limit is set to 0.0080%. The preferred total content of Ca, Mg, and REM is 0.0060% or less.

[0028] Group B: 0.01 to 0.60% in total of one or more elements selected from Cr, Mo, Cu, and Ni. Cr, Mo, Cu, and Ni have the effect of increasing the resistivity of steel and improving iron loss. Therefore, it is preferable that one or more of Cr, Mo, Cu, and Ni are contained in total at 0.01% or more. On the other hand, if added in excess, the hot-rolled annealed sheet is hardened, making the sheet more susceptible to breakage during cold rolling, so the upper limit of the total content is preferably set to 0.40%.

[0029] Group C: 0.0005 to 0.0030% in total of one or more elements selected from Ti, Nb, and V. Ti, Nb, and V have the effect of refining the structure of a hot-rolled annealed sheet, improving toughness, and suppressing sheet fracture during cold rolling. Therefore, the total content of Ti, Nb, and V is preferably 0.0005% or more. On the other hand, excessive addition generates a large amount of fine precipitates, significantly inhibiting grain growth, so the upper limit of the total content of Ti, Nb, and V is preferably 0.0030%.

[0030] Group D: B: 0.0001 to 0.0020% B segregates at grain boundaries to improve toughness and has the effect of suppressing sheet fracture during cold rolling. Therefore, the B content is preferably 0.0001% or more, and more preferably 0.0003% or more. On the other hand, if the B content exceeds 0.0020%, iron borides are formed, and the toughness-improving effect is lost, so the upper limit is preferably 0.0020%.

[0031] Furthermore, in order to improve various properties, it is preferable to contain at least one group of components selected from the following groups E to J.

[0032] Group E: Zn: 0.001 to 0.010% Zn has the effect of coarsening inclusions and promoting grain growth during finish annealing, thereby improving the iron loss of the finish annealed sheet. Therefore, the Zn content is preferably 0.001% or more. On the other hand, even if the Zn content exceeds 0.010%, the above effect saturates, so the upper limit is preferably 0.010%.

[0033] Group F: 0.001 to 0.010% in total of one or more elements selected from Zr, Ta, W, and Se. Zr, Ta, W, and Se form precipitates, reducing the grain size of the hot-rolled annealed sheet, thereby contributing to improved cold rolling. Therefore, it is preferable to contain 0.001% or more in total of one or more elements selected from Zr, Ta, W, and Se. On the other hand, if the total content exceeds 0.010%, the iron loss of the finish-annealed sheet may deteriorate, so the upper limit is preferably set to 0.010%.

[0034] G group: 0.0001 to 0.0200% in total of one or more elements selected from Ga and Ge. Ga and Ge have the effect of improving the texture of the finish-annealed sheet and improving the magnetic properties. For this reason, it is preferable to contain 0.0001% or more in total of one or more elements selected from Ga and Ge. On the other hand, even if the content exceeds 0.0200%, the above effect saturates, so the upper limit is preferably set to 0.0200%.

[0035] Group H: 0.00005 to 0.0020% in total of one or more elements selected from Pb and Bi. Pb and Bi are effective in improving cold rolling by reducing the grain size of the hot-rolled annealed sheet. Therefore, it is preferable to contain 0.00005% or more in total of one or more elements selected from Pb and Bi. On the other hand, if the content exceeds 0.0020%, the iron loss of the finish-annealed sheet deteriorates, so the upper limit is preferably set to 0.0020%.

[0036] Group I: Co: 0.001 to 0.100% Co has the effect of improving magnetic flux density. Therefore, it is preferable to contain 0.001% or more. On the other hand, if it is contained in excess of 0.100%, precipitates are formed, which deteriorates the iron loss of the finish-annealed steel sheet, so the upper limit is preferably set to 0.100%.

[0037] J group: As: 0.0005 to 0.020% As segregates at grain boundaries, reducing the grain size of the hot-rolled annealed sheet, thereby improving cold rollability. Therefore, it is preferable to contain 0.0005% or more. On the other hand, if it is contained in excess of 0.020%, grain boundary fracture is promoted, which actually reduces cold rollability, so the upper limit is preferably set to 0.020%.

[0038] The chemical composition of the hot-rolled annealed sheet for the non-oriented electrical steel sheet according to this embodiment is such that the balance other than the above elements is Fe and unavoidable impurities.

[0039] <Steel structure of hot-rolled annealed sheet for non-oriented electrical steel sheet> Next, the steel structure of the hot-rolled annealed sheet for non-oriented electrical steel sheet according to this embodiment will be described. Average crystal grain size in the rolling direction cross section of the steel sheet: 40 to 250 μm. If the structure of the hot-rolled annealed sheet is coarse, the hot-rolled annealed sheet becomes embrittled and is prone to sheet fracture during cold rolling, so the average crystal grain size is set to 250 μm or less. From the viewpoint of fracture suppression, it is preferably 180 μm or less, and more preferably 120 μm or less. On the other hand, if the average crystal grain size is less than 40 μm, the hot-rolled annealed sheet hardens, increasing the load during cold rolling and making the sheet prone to fracture, so it needs to be 40 μm or more. A preferred average crystal grain size is 60 μm or more.

[0040] Integral intensity of Fe—Al oxides in the steel sheet surface layer: 200 cps·degrees or less Because Fe—Al oxides are hard and have poor wettability with lubricating oil, if they remain on the steel sheet surface, they damage the rolling rolls during cold rolling, increasing the friction coefficient and rolling load, making rolling unstable and leading to sheet breakage. Therefore, Fe—Al oxides must be sufficiently removed in the pickling process, and as an indicator, the integrated intensity of Fe—Al oxides in the steel sheet surface layer, measured by X-ray diffraction on a hot-rolled annealed sheet after pickling, needs to be 200 cps·degrees or less.

[0041] <Method for manufacturing a hot-rolled annealed sheet for a non-oriented electrical steel sheet> Next, a method for manufacturing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to this embodiment will be described.

[0042] The method for manufacturing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to this embodiment includes a hot rolling step of heating and hot-rolling a steel slab having the above-described chemical composition to form a hot-rolled steel sheet, a hot-rolled sheet annealing step of annealing the hot-rolled steel sheet to form a hot-rolled annealed sheet, a shot blasting step of shot-blasting the hot-rolled annealed sheet, and a pickling step of pickling the shot-blasted hot-rolled annealed sheet. In the hot-rolling step, the heating temperature of the steel slab is 1150°C or less, the finish rolling temperature is 960°C or less, and the coiling temperature is 700°C or less. In the hot-rolled sheet annealing step, the annealing temperature is 800°C or more and 1100°C or less, and in the shot blasting step, the shot density is 10 to 40 kg / m ２ The hot-rolled and annealed steel sheet is then subjected to shot blasting. Next, in the pickling step, the shot-blasted steel sheet is pickled at a hydrochloric acid concentration of 5% or more, a pickling temperature of 70°C or more, and a pickling time of 10 seconds or more and 120 seconds or less. This will be explained in detail below.

[0043] [Hot Rolling Process] Steel Slab The elemental composition of the steel slab used to manufacture the hot-rolled annealed sheet for the non-oriented electrical steel sheet of this embodiment is adjusted to the range described above. The method for producing the steel is not particularly limited and may be a known refining process such as a converter, electric furnace, or vacuum degasser. Continuous casting is preferred as the method for producing the steel slab. Iron scrap or direct reduced iron may also be used as the raw material. In particular, iron scrap is preferably used because elements such as Cu and Ni, which are useful for reducing iron loss, can be obtained inexpensively from iron scrap.

[0044] Heating temperature: 1150°C or less Hot rolling is a process in which a steel slab having the above-mentioned composition is produced and then immediately hot-rolled, or cooled and heated to a predetermined temperature, and then hot-rolled to obtain a hot-rolled sheet of a predetermined thickness. If the heating temperature of the slab is too high, AlN and MnS remelt and precipitate finely in processes after hot rolling, deteriorating grain growth and iron loss. Therefore, the upper limit is set to 1150°C. In order to coarsen AlN and MnS in the steel slab and improve grain growth and iron loss, the heating temperature is preferably 1000°C or higher. Furthermore, from the viewpoint of stable production by reducing the hot rolling load, a heating temperature of 1050°C or higher is more preferable.

[0045] Finish rolling temperature: 960°C or less If the finish rolling temperature of hot rolling exceeds 960°C, the scale of the hot-rolled sheet becomes thick and the pickling property deteriorates, so the finish rolling temperature is set to 960°C or less. A preferred finish rolling temperature is 920°C or less. On the other hand, if the finish rolling temperature is too low, the rolling load increases, and the rolling force becomes large, so the lower limit is preferably 750°C. A more preferred temperature is 780°C or more.

[0046] Coiling temperature: 700°C or less If the coiling temperature exceeds 700°C, scale increases, and in particular Fe—Al-based oxides become thicker, resulting in a decrease in pickling properties, so the upper limit is set to 700°C. The coiling temperature is preferably 620°C or less. On the other hand, if the coiling temperature is too low, the temperature fluctuations increase due to rapid cooling from the end of hot rolling to coiling, so the lower limit is preferably set to 450°C. From the viewpoint of coarsening precipitates during coiling and reducing iron loss, the coiling temperature is preferably 480°C or more.

[0047] [Hot-rolled sheet annealing process] Hot-rolled sheet annealing temperature: 800 to 1100°C. Hot-rolled sheet annealing is performed to homogenize the structure and control the ferrite grain size within a predetermined range, thereby improving fracture resistance during cold rolling and improving magnetic properties after cold rolling and finish annealing. If the hot-rolled sheet annealing temperature is higher than 1100°C, the structure becomes too coarse, resulting in a decrease in toughness and making the sheet more susceptible to breakage during cold rolling, so it must be 1100°C or lower. A preferred hot-rolled sheet annealing temperature is 1030°C or lower. Furthermore, from the viewpoint of suppressing scale growth during hot-rolled sheet annealing, it is preferable to set it to 960°C or lower. On the other hand, if the hot-rolled sheet annealing temperature is lower than 800°C, the grain size does not become sufficiently large, resulting in a decrease in magnetic properties after finish annealing, so it must be 800°C or higher. A preferred hot-rolled sheet annealing temperature is 900°C or higher. The annealing time is not particularly specified, but it is preferably 10 seconds or longer from the viewpoint of ensuring uniformity.

[0048] [Shot blasting process] Shot blasting density: 10 to 40 kg / m ２ Shot blasting is performed on the hot-rolled annealed sheet before pickling to introduce cracks into the scale, which promotes scale removal during pickling. Since Fe-Al scale is particularly difficult to dissolve in acid, it is necessary to introduce cracks to allow the acid to penetrate the exposed base steel, dissolving and removing it from the base steel side at the base steel interface. The shot blasting density required for this is 10 kg / m ２ Preferably 15 kg / m ２ On the other hand, 40 kg / m ２ If the projection density exceeds 40 kg / m, not only will cracks be introduced into the scale, but the surface area of ​​the base steel will also be deformed, which will become the starting point for sheet fracture during cold rolling. ２ The preferred projection density is 35 kg / m ２ The following is the result.

[0049] If the particle size of the shot blast particles is large, the number of collisions per unit area decreases even with the same projection density, i.e., the number of cracks introduced into the scale decreases, resulting in poor pickling properties. Therefore, the average particle size of the shot blast particles is preferably 0.50 mm or less. From the viewpoint of promoting pickling properties, 0.30 mm or less is more preferable. Conversely, if the particle size is too small, the crack introduction effect is weakened, so the average particle size of the shot blast particles is preferably 0.15 mm or more. The average particle size of the shot blast particles can be measured, for example, by the particle size analysis - laser diffraction and scattering method described in JIS Z 8825:2013. Furthermore, if the shot blast particles are soft, they will deform when colliding with the steel plate, making it difficult to efficiently introduce cracks into the scale. Therefore, the Vickers hardness of the shot blast particles is preferably 400 HV or more.

[0050] [Brush grinding process (before pickling)] Instead of shot blasting, brush grinding can also be performed on hot-rolled annealed sheets before pickling, which can introduce cracks into the scale and promote scale removal during pickling. To ensure uniform grinding of the steel sheet surface, it is preferable to use a brush roll for brush grinding. The brush material and grinding conditions can be selected appropriately, but from the perspective of uniform grinding that follows the shape of the steel sheet, it is preferable to use chemical fibers, which are softer than metal, for the brush bristles. Furthermore, from the perspective of efficiently introducing cracks into the scale, it is preferable for the brush to contain abrasive grains such as alumina, silicon carbide, or diamond. During brush grinding, it is preferable to spray cooling water to remove grinding powder and prevent the brush from overheating.

[0051] [Pickling Process] Pickling: Hydrochloric acid concentration of 5% or more, pickling temperature of 70°C or more, pickling time of 10 seconds or more and 120 seconds or less. The pickling process is a process for removing scale from the hot-rolled annealed sheet that has been subjected to the above-mentioned shot blasting and brush grinding. By thoroughly removing not only iron oxide but also Fe-Al-based scale, sheet breakage during cold rolling can be suppressed. For this reason, the hydrochloric acid concentration is set to 5% or more, preferably 8% or more. Although there is no particular upper limit, the hydrochloric acid concentration is preferably set to 20% or less to prevent over-pickling. To promote pickling, the temperature of the pickling solution (pickling temperature) is set to 70°C or more, preferably 75°C or more. If the pickling temperature is too high, over-pickling is likely to occur and the amount of evaporation of the pickling solution increases, increasing production costs, so it is preferably set to 96°C or less. To ensure sufficient pickling, the pickling time is set to 10 seconds or more, preferably 15 seconds or more. If the pickling time exceeds 120 seconds, hydrogen generation increases and the steel sheet becomes more susceptible to fracture during cold rolling due to hydrogen embrittlement, so the upper limit of the pickling time is set to 120 seconds. As described above, the pickling properties vary depending on the Al content, the hot rolling finish temperature, and the coiling temperature, so the pickling solution may be adjusted by adding a pickling accelerator or a pickling inhibitor as needed.

[0052] Furthermore, in the present invention, from the viewpoint of completely removing Fe-Al scale, it is preferable to add the following process to the descaling process described above. A rolling and / or tensile bending process with an elongation rate of 0.1 to 10.0% before the hot-rolled sheet annealing process: By introducing cracks into the scale, particularly the Fe-Al scale, present at the time of hot-rolling and exposing the base steel, the oxidation behavior during hot-rolled sheet annealing changes. That is, iron oxides that are relatively easily soluble in acid are generated in the exposed areas of the base steel. These iron oxides dissolve during pickling and subsequently become the starting point for dissolution of the base steel, which in turn removes the Fe-Al scale. For this reason, it is preferable to elongate the hot-rolled sheet by light rolling and / or tensile bending. It is preferable to subject the hot-rolled sheet before hot-rolling annealing to an elongation rate of 0.1% or more using a skin-pass rolling mill or tension leveler. The elongation rate is preferably 0.3% or more. If the elongation exceeds 10.0%, not only will the above effects saturate, but the average crystal grain size of the hot-rolled annealed sheet will become too large due to strain-induced grain growth, so the elongation is preferably 10.0% or less, and more preferably 6.0% or less. Note that, when rolling and / or tensile bending at an elongation of 0.1 to 10.0% is performed before annealing the hot-rolled sheet, it is preferable to perform the above processing so that the integrated strength of the hot-rolled annealed sheet after pickling is 150 cps degrees or less.

[0053] [Brush Grinding Process (After Pickling)] Brush grinding is preferably performed on the front and back surfaces of the steel sheet after pickling to mechanically remove any Fe-Al-based scale remaining during pickling. Removing all scale, including Fe-based and Fe-Al-based scale, by brush grinding alone requires larger equipment, resulting in increased installation and maintenance costs. Therefore, removing most of the scale by pickling and then removing only the remaining Fe-Al-based scale by brush grinding can reduce equipment costs. To ensure uniform grinding of the steel sheet surface, a brush roll is preferably used for brush grinding. While the brush material and grinding conditions can be selected appropriately, chemical fibers, which are softer than metals, are preferred for the brush bristles in order to conform to the steel sheet shape and ensure uniform grinding. To efficiently remove Fe-Al-based scale, the brush preferably contains abrasive grains such as alumina, silicon carbide, or diamond. Cooling water is preferably sprayed during brush grinding to remove grinding dust and prevent the brush from overheating. When brush grinding is performed on the front and back surfaces of the steel sheet after pickling, it is preferable to perform the brush grinding so that the integrated strength of the hot-rolled annealed sheet after brush grinding is 60 cps·degrees or less.

[0054] Next, a method for producing a non-oriented electrical steel sheet from the hot-rolled annealed sheet obtained by the above-mentioned production method of the present invention will be described. [Cold Rolling Step] The pickled hot-rolled annealed sheet is preferably cold-rolled once or twice or more times including intermediate annealing to produce a cold-rolled sheet of the final thickness. From the viewpoint of production efficiency, it is preferable to use a tandem rolling mill, but a reverse rolling mill may also be used, and rolling may be carried out in a conventional manner.

[0055] [Finish annealing step] Finish annealing temperature: 700 to 1100°C. The finish annealing step after the cold rolling is a step in which the cold-rolled sheet undergoes recrystallization and grain growth to obtain good magnetic properties. The soaking temperature in the finish annealing is preferably 700°C or higher, and more preferably 800°C or higher. On the other hand, if the soaking temperature in the finish annealing is too high, nitriding may occur during annealing or the crystal grains may become too coarse, resulting in deterioration of iron loss. Therefore, the soaking temperature is preferably 1100°C or lower, and more preferably 1050°C or lower.

[0056] The embodiments of the present invention will be further explained by way of examples. Note that the present invention is not limited to the manufacturing conditions and product performance shown in the following examples. The embodiments can achieve the desired performance within the scope of the present invention.

[0057] Example 1 Steel containing the various components shown in Table 1, with the remainder consisting of Fe and inevitable impurities, was melted using a conventional refining process and then formed into a slab using a continuous casting method. The slab was then heated in a gas furnace under the conditions shown in Tables 2-1 and 2-2, and hot-rolled, consisting of rough rolling and finish rolling, to obtain a hot-rolled sheet having a thickness of 1.8 mm and a width of 1,200 mm. The hot-rolled sheet was then subjected to hot-rolled sheet annealing and then pickled to obtain a hot-rolled annealed sheet. Some of the hot-rolled sheets underwent either light rolling using a skin-pass rolling mill before hot-rolling annealing or brush grinding after pickling. For brush grinding, a silicon carbide brush roll with nylon bristles and silicon carbide abrasive grains was used. The elongation rate (%) of light rolling before hot rolling and annealing, and the torque (N·m) and rotation speed (rpm) during grinding with a brush roll after pickling are also shown in Tables 2-1 and 2-2.

[0058] Steel sheet structure Samples were cut out from the obtained hot-rolled annealed sheets so that the cross section of the sheet thickness in the rolling direction could be observed, and then the samples were embedded, polished, and etched to reveal the structure, after which the steel sheet structure was observed. The average grain size was calculated from the photographed structure by image analysis. Here, the average grain size was defined as the circle equivalent diameter.

[0059] A sample measuring 25 mm x 30 mm x 10 mm was cut out from the hot-rolled and annealed sheet, and the amount of remaining scale on the steel sheet surface was measured by X-ray diffraction. The measurement was performed with the X-ray incident angle set at 1 degree, and the Fe-Al oxides (hercynite, FeAl ２ O ４ The integrated intensity of the (311) plane peak of the (311) plane was calculated.

[0060] The obtained hot-rolled annealed sheet was rolled in a tandem cold rolling mill to a finished thickness of 0.25 mm, with the sheet passing speed at the outlet of the final stand being 600 m / min excluding the unsteady portion near the weld, for a total of 8,000 m. A sheet that broke once or more was marked with ×, a sheet that did not break was marked with ◯, and a sheet that did not break and had small load fluctuations in the first stand was marked with ⊚. Here, the small load fluctuation means that the average value of the rolling load of #1st stand when rolling at 600 m / min in the tandem rolling mill is L ａｖｅ , when the difference between the maximum and minimum values ​​of the rolling load is ΔL, the average value L of the rolling load ａｖｅ and the ratio ΔL / L of the difference ΔL between the maximum and minimum values ａｖｅ ×100 is 10% or less.

[0061] Iron loss W of finish annealed sheet １０／４００ The above cold-rolled sheet was subjected to finish annealing under the conditions shown in Tables 2-1 and 2-2. The soaking time was 10 seconds. Test pieces with a width of 30 mm and a length of 280 mm were taken from the obtained finish-annealed sheet in the L direction (rolling direction) and the C direction (direction perpendicular to the rolling direction), and the iron loss W １０／４００ was measured.

[0062] The measurement results are shown in Tables 2-1 and 2-2. These results show that by controlling the manufacturing conditions of the steel sheet within the ranges of the present invention, it is possible to obtain a hot-rolled and annealed sheet for non-oriented electrical steel sheet that is both able to prevent breakage during cold rolling after annealing the hot-rolled sheet and has excellent magnetic properties after annealing the cold-rolled sheet.

[0063]

[0064]

[0065]

[0066] Example 2 The slab produced in Example 1, containing the various components shown in Table 1 with the balance consisting of Fe and inevitable impurities, was heated in a gas furnace under the conditions shown in Tables 3-1 and 3-2, and then hot-rolled, consisting of rough rolling and finish rolling, to obtain a hot-rolled sheet having a thickness of 1.8 mm and a width of 1,200 mm. The hot-rolled sheet was then subjected to hot-rolled sheet annealing, brush grinding, and pickling to obtain a hot-rolled annealed sheet. Some of the hot-rolled sheets underwent either light rolling before hot-rolling annealing using a skin-pass rolling mill or brush grinding after pickling. For brush grinding, a silicon carbide brush roll with nylon bristles and silicon carbide abrasive grains was used. The elongation rate (%) of light rolling before hot rolling annealing, the torque (N m) and rotation speed (rpm) during grinding with a brush roll before pickling, and the torque (N m) and rotation speed (rpm) during grinding with a brush roll after pickling are also shown in Tables 3-1 and 3-2.

[0067] Steel sheet structure Samples were cut out from the obtained hot-rolled annealed sheets so that the cross section of the sheet thickness in the rolling direction could be observed, and then the samples were embedded, polished, and etched to reveal the structure, after which the steel sheet structure was observed. The average grain size was calculated from the photographed structure by image analysis. Here, the average grain size was defined as the circle equivalent diameter.

[0068] A sample measuring 25 mm x 30 mm x 10 mm was cut out from the hot-rolled and annealed sheet, and the amount of remaining scale on the steel sheet surface was measured by X-ray diffraction. The measurement was performed with the X-ray incident angle set at 1 degree, and the Fe-Al oxides (hercynite, FeAl ２ O ４ The integrated intensity of the (311) plane peak of the (311) plane was calculated.

[0069] The obtained hot-rolled annealed sheet was rolled in a tandem cold rolling mill to a finished thickness of 0.25 mm, with the sheet passing speed at the outlet of the final stand being 600 m / min excluding the unsteady portion near the weld, for a total of 8,000 m. A sheet that broke once or more was marked with ×, a sheet that did not break was marked with ◯, and a sheet that did not break and had small load fluctuations in the first stand was marked with ⊚. Here, the small load fluctuation means that the average value of the rolling load of #1st stand when rolling at 600 m / min in the tandem rolling mill is L ａｖｅ, when the difference between the maximum and minimum values ​​of the rolling load is ΔL, the average value L of the rolling load ａｖｅ and the ratio ΔL / L of the difference ΔL between the maximum and minimum values ａｖｅ ×100 is 10% or less.

[0070] Iron loss W of finish annealed sheet １０／４００ The above cold-rolled sheet was subjected to finish annealing under the conditions shown in Tables 3-1 and 3-2. The soaking time was 10 seconds. Test pieces with a width of 30 mm and a length of 280 mm were taken from the obtained finish-annealed sheet in the L direction (rolling direction) and the C direction (direction perpendicular to the rolling direction), and the iron loss W １０／４００ was measured.

[0071] The measurement results are shown in Tables 3-1 and 3-2. These results show that by controlling the manufacturing conditions of the steel sheet within the ranges of the present invention, it is possible to obtain a hot-rolled and annealed sheet for non-oriented electrical steel sheet that is both able to prevent breakage during cold rolling after annealing of the hot-rolled sheet and has excellent magnetic properties after annealing of the cold-rolled sheet.

[0072]

[0073]

Claims

1. A hot-rolled annealed sheet for non-oriented electrical steel sheet, having a component composition containing, by mass%, C: 0.0050% or less, Si: 2.0 to 5.0%, Mn: 0.2 to 2.0%, P: 0.030% or less, S: 0.0050% or less, Al: 0.25 to 2.50%, N: 0.0050% or less, O: 0.0050% or less, one or more Sn and Sb: 0.01 to 0.20% in total, with the balance being Fe and unavoidable impurities, wherein the average crystal grain size in the rolling direction cross section of the steel sheet is 40 to 250 μm, and the integrated intensity of Fe-Al-based oxides in the steel sheet surface layer as measured by X-ray diffraction is 200 cps-degree or less.

2. The hot-rolled annealed sheet for non-oriented electrical steel sheet according to claim 1, further comprising, in addition to the above-mentioned composition, one or more components selected from the following groups A to D in mass %: Group A: 0.0010 to 0.0080% in total of one or more elements selected from Ca, Mg and REM; Group B: 0.01 to 0.60% in total of one or more elements selected from Cr, Mo, Cu and Ni; Group C: 0.0005 to 0.0030% in total of one or more elements selected from Ti, Nb and V; Group D: B: 0.0001 to 0.0020% 3. The hot-rolled annealed sheet for non-oriented electrical steel sheet according to claim 1 or 2, further comprising, in addition to the above-mentioned composition, one or more components selected from the following groups E to J in mass %: Group E: Zn: 0.001-0.010% Group F: one or more elements selected from Zr, Ta, W and Se in total of 0.001-0.010% Group G: one or more elements selected from Ga and Ge in total of 0.0001-0.0200% Group H: one or more elements selected from Pb and Bi in total of 0.00005-0.0020% Group I: Co: 0.001-0.100% Group J: As: 0.0005-0.020% 4. The method includes a hot rolling process of heating a steel slab having a composition containing, by mass%, C: 0.0050% or less, Si: 2.0 to 5.0%, Mn: 0.2 to 2.0%, P: 0.030% or less, S: 0.0050% or less, Al: 0.25 to 2.50%, N: 0.0050% or less, O: 0.0050% or less, Sn and / or Sb: one or more types in total 0.01 to 0.20%, with the balance being Fe and unavoidable impurities, and hot rolling the slab to obtain a hot rolled steel sheet; a hot rolled sheet annealing process of annealing the hot rolled steel sheet to obtain a hot rolled annealed sheet; a shot blasting process of subjecting the hot rolled annealed sheet to shot blasting; and a pickling process of pickling the shot blasted hot rolled annealed sheet, In the hot rolling process, the heating temperature of the steel slab is 1150°C or less, the finish rolling temperature is 960°C or less, and the coiling temperature is 700°C or less; in the hot rolled sheet annealing process, the annealing temperature is 800°C or more and 1100°C or less; and in the shot blasting process, the shot density is 10 to 40 kg / m ２ and in the pickling step, the shot-blasted steel sheet is pickled with a hydrochloric acid concentration of 5% or more, a pickling temperature of 70°C or more, and a pickling time of 10 s or more and 120 s or less.

5. The method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to claim 4, characterized in that the steel slab further contains, in mass %, one or more elements selected from the following groups A to D in addition to the above-mentioned composition: Group A: 0.0010 to 0.0080% in total of one or more elements selected from Ca, Mg and REM; Group B: 0.01 to 0.60% in total of one or more elements selected from Cr, Mo, Cu and Ni; Group C: 0.0005 to 0.0030% in total of one or more elements selected from Ti, Nb and V; Group D: B: 0.0001 to 0.0020% 6. A method for producing a hot-rolled annealed sheet for non-oriented electrical steel sheet according to claim 4 or 5, characterized in that the steel slab further contains, in addition to the above-mentioned chemical composition, one or more components selected from the following groups E to J, in mass %: ・Group E; Zn: 0.001-0.010% F group: one or more selected from Zr, Ta, W and Se, total of 0.001-0.010% G group: one or more selected from Ga and Ge, total of 0.0001-0.0200% H group: one or more selected from Pb and Bi, total of 0.00005-0.0020% I group: Co: 0.001-0.100% J group: As: 0.0005-0.020% 7. A method for manufacturing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to any one of claims 4 to 6, characterized in that before annealing the hot-rolled steel sheet, the hot-rolled steel sheet is subjected to rolling and / or tensile bending with an elongation rate of 0.1 to 10.0%.

8. A method for manufacturing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to any one of claims 4 to 7, characterized in that after the pickling process, the front and back surfaces of the pickled steel sheet are brush ground.

9. A method for producing a non-oriented electrical steel sheet, comprising the steps of: subjecting a hot-rolled annealed sheet obtained by the method according to any one of claims 4 to 8 to one cold rolling or two or more cold rolling steps including intermediate annealing to obtain a cold-rolled sheet of a final thickness; and annealing the cold-rolled sheet at a soaking temperature of 700 to 1100°C to obtain a cold-rolled annealed sheet.

10. A method for producing a hot-rolled steel sheet, comprising: a hot rolling process for heating a steel slab having a component composition containing, by mass%, C: 0.0050% or less, Si: 2.0 to 5.0%, Mn: 0.2 to 2.0%, P: 0.030% or less, S: 0.0050% or less, Al: 0.25 to 2.50%, N: 0.0050% or less, O: 0.0050% or less, Sn and / or Sb: one or more types in total 0.01 to 0.20%, with the balance being Fe and unavoidable impurities; a hot-rolled sheet annealing process for annealing the hot-rolled steel sheet to produce a hot-rolled annealed sheet; a brush grinding process for brush-grinding the hot-rolled annealed sheet; and a pickling process for pickling the brush-ground hot-rolled annealed sheet, A method for manufacturing a hot-rolled annealed sheet for non-oriented electrical steel sheet, in which in the hot rolling process, the heating temperature of the steel slab is 1150°C or less, the finish rolling temperature is 960°C or less, and the coiling temperature is 700°C or less; in the hot-rolled sheet annealing process, the annealing temperature is 800°C or more and 1100°C or less; and in the pickling process, the brush-ground steel sheet is pickled with a hydrochloric acid concentration of 5% or more, a pickling temperature of 70°C or more, and a pickling time of 10 s or more and 120 s or less.

11. The method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to claim 10, characterized in that the steel slab further contains, in mass %, one or more elements selected from the following groups A to D in addition to the above-mentioned chemical composition: Group A: 0.0010 to 0.0080% in total of one or more elements selected from Ca, Mg and REM; Group B: 0.01 to 0.60% in total of one or more elements selected from Cr, Mo, Cu and Ni; Group C: 0.0005 to 0.0030% in total of one or more elements selected from Ti, Nb and V; Group D: B: 0.0001 to 0.0020% 12. A method for producing a hot-rolled annealed sheet for non-oriented electrical steel sheet as described in claim 10 or 11, characterized in that the steel slab further contains, in addition to the above-mentioned chemical composition, one or more components selected from the following groups E to J, in mass %: ・Group E; Zn: 0.001-0.010% F group: one or more selected from Zr, Ta, W and Se, total of 0.001-0.010% G group: one or more selected from Ga and Ge, total of 0.0001-0.0200% H group: one or more selected from Pb and Bi, total of 0.00005-0.0020% I group: Co: 0.001-0.100% J group: As: 0.0005-0.020% 13. A method for producing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to any one of claims 10 to 12, characterized in that before annealing the hot-rolled steel sheet, the hot-rolled steel sheet is subjected to rolling and / or tensile bending with an elongation rate of 0.1 to 10.0%.

14. A method for manufacturing a hot-rolled annealed sheet for a non-oriented electrical steel sheet according to any one of claims 10 to 13, characterized in that after the pickling process, the front and back surfaces of the pickled steel sheet are brush ground.

15. A method for producing a non-oriented electrical steel sheet, comprising the steps of: subjecting a hot-rolled annealed sheet obtained by the method according to any one of claims 10 to 14 to one cold rolling or two or more cold rolling steps including intermediate annealing to obtain a cold-rolled sheet of a final thickness; and annealing the cold-rolled sheet at a soaking temperature of 700 to 1100°C to obtain a cold-rolled annealed sheet.

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