Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/147—Alloys characterised by their composition
  • H01F1/14766—Fe-Si based alloys
  • H01F1/14791—Fe-Si-Al based alloys, e.g. Sendust
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/16—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of sheets
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C2202/00—Physical properties
  • C22C2202/02—Magnetic

Definitions

• the present invention relates to a high-strength non-oriented electrical steel sheet and a method for producing the same.
• the steel sheet of the present invention is particularly suitable for use in electromagnetic parts subjected to large stresses, such as a rotor of a high-speed rotating machine.
• examples of the high-speed rotating machine include a turbine generator, a drive motor for an electric vehicle and a hybrid vehicle, or a servo motor for a robot or machine tool.
• centrifugal force acting on (rotor) increases in proportion to the radius of rotation and in proportion to the square of the rotation speed. For this reason, it is particularly strong for rotor materials for medium and large high-speed motors
• a non-oriented electrical steel sheet that has been stamped and punched is used as the core for the rotor.
• a higher strength steel is used.
• a steel mouthpiece must be used.
• the porcelain rotor is not a laminated body but an integral body, there is a problem that the eddy current loss is significantly higher than that of a rotor laminated with electrical steel sheets. .
• Steel plate strengthening methods include solid solution hardening, precipitation strengthening, fine grain graining, and complex-structure strengthening. In general, it is extremely difficult to achieve both strength and magnetic properties because both of these strengthening methods degrade the magnetic properties.
• Several proposals have been made regarding non-oriented electrical steel sheets having high strength.
• the Si content is increased to 3.5 to 7.0% (mass./., The same applies hereinafter), and Ti, W, Methods have been proposed to increase the strength by adding elements such as Mo, Mn, Ni, Co, and Al.
• the crystal grain size is set to 0.01 to 5.0 mm to improve the magnetic characteristics. A method has been proposed.
• Japanese Patent Application Laid-Open No. 2-22442 proposes a method for strengthening a solid solution with ⁇ and Ni in steel having a Si content of 2.0 to 3.5%.
• JP-A-6-330255 discloses a technique that uses precipitation strengthening and fine grain hardening by carbonitrides of Nb, Zr, Ti, and V in steel having a Si content of 2.0 or more and less than 4.0%.
• Japanese Patent Laid-Open No. 2-8346 proposes a technique for adding both solid solution strengthening by adding Mn and Ni to achieve both high strength and magnetic properties.
• JP-A-2001-234303 discloses a high-strength electrical steel sheet that focuses on fatigue characteristics by controlling the crystal grain size of an electrical steel sheet with a Si content of 3.3% or less according to the steel composition.
• a technique for achieving a fatigue limit of 350 MPa or more is disclosed.
• this method has a low fatigue limit level (maximum of about 430MPa in actual results) and does not satisfy the level demanded recently, for example, fatigue limit: 500MPa or more.
• Japanese Patent Laid-Open No. 2005-113185 states that a steel containing 0.2-3.5% Si has a work hardening structure remaining in the steel. A technique to increase the strength is proposed by doing so.
• heat treatment is not performed after cold rolling, or even if it is performed, it does not reach a level corresponding to holding at 750 ° C or higher for 30 seconds or longer, preferably 700 ° C or lower.
• 750 ° C or lower means of 650 ° C or lower, 600 ⁇ or lower, 550 ° C or lower, and 500 ° C or lower are disclosed.
• 750 ⁇ Examples of 30% annealing and 5% processed texture, 700 ° C-30 seconds 20%, 600% -30 seconds 50%.
• finish annealing of non-oriented electrical steel sheets is performed using a continuous annealing furnace, and the inside of the furnace is adjusted to an atmosphere containing hydrogen gas of several percent or more in order to suppress oxidation of the steel sheet surface. It is customary.
• a continuous annealing facility in order to perform low temperature annealing below 700 ° C, it takes time to switch the furnace temperature setting, and in order to avoid a hydrogen explosion, the atmosphere in the furnace must be replaced. There will be significant operational constraints, such as the need.
• the recrystallization rate of the crystal structure is set to 95% or less and the balance is substantially strengthened with a rolled structure.
• this formula when heat treatment is performed at 700, for example, about 5.9% or more of Si is required.
• JP-A-2005-264315 also discloses that an electrical steel sheet containing 0.2% to 4.0% of Si and having a ferrite phase as a main phase is added with Ti, Nb, Ni, etc.
• a method for producing and strengthening an intermetallic compound having a diameter of 0.050 ⁇ m or less is disclosed. With this technology Has a tensile strength and wear resistance of 60 kgf / mm 2 or more, and can manufacture non-oriented electrical steel sheets with excellent magnetic flux density and iron loss without impairing cold rolling properties. Disclosure of the invention
• an object of the present invention is to provide non-oriented high strength and excellent plate shape and magnetic properties without substantially adding restrictions on steel plate production and new processes to the production of ordinary non-oriented electrical steel sheets.
• An electrical steel sheet and a method for producing the same are provided.
• Another object of the present invention is to propose a non-oriented electrical steel sheet having high strength, excellent magnetic properties and fatigue properties and excellent manufacturability, together with its advantageous manufacturing method. To do.
• the gist of the present invention is as follows.
• C and N are suppressed to C: 0.010% or less and N: 0,01.0% or less, and C + N ⁇ 0.010%, Si: 1.5% or more and 5.0% or less, Mn: 3.0%
• A1 3.0% or less
• P 0.2% or less
• S 0.01% or less
• Ti within 0.05% or more and 0.8% or less
• Presence of (non-recrystallized, recovery structure) 1 High strength non-oriented electrical steel sheet, characterized by an area ratio of 50 ⁇ / ⁇ or more.
• recrystallization is a phenomenon in which new crystal grains with low defect density and thermodynamic stability are formed, and they grow while engulfing the surrounding matrix with high defect density.
• the defect density decreases rapidly as the grain boundaries move.
• recovery is a phenomenon in which the strain energy decreases as a result of the defect itself being thermally moved toward the sink and decreasing the dislocation density without passing through the grain boundary.
• the annealing temperature is 500 ° C or higher.
• recrystallization proceeds abruptly at 600 to 650 t: or more, and most of it becomes a recrystallized structure at 700: or more.
• the recrystallized structure and the unrecrystallized recovered structure can be easily distinguished by observation of the structure with a light microscope (microscopic structure: micrc ⁇ gagture).
• the structure observation can be performed by polishing the section in the thickness direction, which is usually performed, and then etching with a niter nore (nitric alcohol solution) or the like.
• Si 1.5% or more and 4.0% or less by mass%.
• the mass percentage is Ni: 0.1 to 5.0%, Sb: 0.002 to 0.1%, Sn: 0.002 to 0.1%, B: 0.001 to 0.01%, Ca: 0.001 to 0.01%, Rem : 0.001-0.01% and Co: It is preferable to further contain at least one selected from the group consisting of 0.2 to 5.0 ° / 0 . These preferable conditions may be freely combined.
• a method for producing a high-strength non-oriented electromagnetic copper sheet characterized by being performed at a temperature of from ⁇ ° C. to 850 ° C. and a strip unit tension in furnace of 2.5 MPa to 20 MPa.
• the tension in the furnace is the unit area of the steel strip in the furnace section where the steel strip reaches the maximum temperature in the annealing furnace (mostly in the heating section and the soaking section).
• the balance of the steel slab component is preferably Fe and inevitable impurities.
• the invention (2) is particularly preferably used to obtain a steel sheet according to the invention (1), that is, a steel sheet having an area ratio of unrecrystallized recovery structure of 50% or more.
• a steel sheet according to the invention (1) that is, a steel sheet having an area ratio of unrecrystallized recovery structure of 50% or more.
• Ti and V are contained within a range that satisfies the total: 0.01% or more and 0.8% or less and (Ti + V) / (C + N) ⁇ 16, with the balance being Fe and A high-strength, non-oriented electrical steel sheet with excellent manufacturability and excellent fatigue and magnetic properties, characterized by the composition of inevitable impurities.
• Nb and Zr are included within the total range of 0.01% or more and 0.5% or less and (Nb + Zr) / (C + N) ⁇ 10 and the balance is Fe.
• the final plate thickness is preferably 0.15 mm or more.
• the inventions of (1) and (2) above by restricting the component composition and the structure, the high strength and the plate can be obtained without adding restrictions or new processes in the production of steel sheets.
• a non-oriented electrical steel sheet excellent in shape and magnetic properties can be provided.
• according to the present invention in particular, according to the inventions of (3) ((3-1) to (3-4)) and (4), it is needless to say that it has high strength and excellent magnetic properties. It is possible to stably obtain non-oriented electrical steel sheets with excellent characteristics and excellent manufacturability. Monkey. Brief Description of Drawings
• N A graph showing the amount. .
• the high strength required here is specifically a tensile strength of 600 MPa or more, preferably 700 MPa or more, and more preferably 800 MPa or more.
• the required magnetic properties, especially high frequency low iron loss properties, for example, in a non-oriented electrical steel sheet with a thickness of 0.35 mm, W 10/400 value is 50 W / kg or less, preferably 40 W Z kg or less.
• the level is desirably 30 W / kg or less.
• the finish annealing temperature must be low at 600 ° C or lower.
• problems such as deterioration of the steel plate shape, and the change of the furnace temperature conditions for the replacement of the annealing atmosphere require a great deal of time and workload. Need to be resolved.
• Fig. 1 shows that the amount of Ti added and the final annealing temperature (soaking time 20 s) on the recrystallization behavior of 2.8% Si-0.35% A1 steel reduced to C + N ⁇ 0.01%.
• the effect of Results are shown.
• the horizontal axis of the graph is the Ti amount (mass. / 0 )
• the vertical axis is the annealing temperature (° C)
• the numbers in each circle are the recrystallization ratio (area%) under the conditions.
• the recrystallization rate is also calculated from the optical structure observation result in the cross section in the plate thickness direction, and the ratio (area%) of the unrecrystallized recovery structure is 100 ⁇ recrystallization rate (area%).
• Ti is Ri toxic elements der degrading the magnetic properties, but being controlled to 0.005 mass 0/0 or less is generally, in the Ti-containing levels 650 ° C or higher Since recrystallization proceeds rapidly, it is necessary to perform final annealing at a low temperature of 600 ° C or lower in order to obtain a stable recovery structure.
• cold crucible induction melting furnace that can produce ultra-high purity steel is vacuum high-frequency melting.
• the amount of Si was controlled within the range of 4.1 to 4.3%, and test steel ingots with various C and N contents were melted.
• the steel ingot obtained was hot-rolled to plate thickness: 2 and annealed at 900 (hot-rolled plate annealing), and then cold-rolled to plate thickness: 0.35 mm.
• a hot-rolled annealed plate was cut into a width of 30 mm, and a repeated bending test was performed at a temperature of 30 at a bending radius of 15 mm and a bending angle of 90 ° to evaluate the plate-lineability on the production line.
• the frequency of breaks in the production line increases when the number of repeated bending times is less than 10.
• the evaluation of cold rollability Then, the edge crack length of the end face of the hot-rolled annealed plate was measured.
• Figures 2 and 3 show the results.
• the horizontal axis of the graph is the amount of steel (C + N) (mass%)
• the vertical axis is the plate-passability (number of bendings) and cold-rollability in the production line (depth of ear cracks on the end face of the rolled plate).
• the platenability (bending characteristics of hot-rolled sheet) and cold-rollability (ear crack depth), that is, manufacturability in the production line, is strongly related to the total amount of C and N. It became clear that it was dependent. That is, if C + N is reduced to 0.0015% or less in total, 4.2% Si class high-alloy steel will show sufficient manufacturability-but if the amount of C + N increases, manufacturability will deteriorate rapidly.
• the amount of Si is controlled in the range of 4.1 to 4.3%, and the total amount of C + N is (1) in the range of 0.0038 to 0.0048%, (2) in the range of 0.0074 to 0.0092%, (3 ) Steel ingots were produced that were controlled to four levels of 0.001 to 0.0196% and (4) 0.0353 to 0,0391%, with various additions of Ti.
• the sheet thickness was hot-rolled to 2 mm, hot-rolled sheet annealed at 900 ° C, then cold-rolled to sheet thickness: 0.35 mm, and finished annealed at 950 ⁇ :.
• the samples obtained in this way were examined for sheet-passability (bending characteristics of hot-rolled sheets) and cold-rollability (ear crack depth) in the production line.
• the results are shown in Figs.
• the horizontal axis in Fig. 4 and Fig. 6 is Ti amount (mass. / 0 ) in steel
• the horizontal axis in Fig. 5 and Fig. 7 is C + N amount (the sum of C amount in steel and N amount in steel).
• the black rhombus decree is the same level (1) as ⁇ + ⁇
• the black square is the same level (2)
• the black triangle ⁇ indicates the same level (3)
• the cross X indicates the same level (4).
• the horizontal axis of the graph is the Ti content (mass%) in steel
• the vertical axis in Fig. 8 is the tensile strength (TS) (MPa
• the vertical axis in Fig. 9 is the fatigue limit (MPa).
• the relationship between the marked symbol and the level of C + N is the same as in Figs.
• the tensile strength TS increased with the amount of Ti added, and the effect became more pronounced as the C + N content increased.
• the reason for this is thought to be that the higher the C + N content, the higher the strength due to precipitation strengthening by Ti carbonitride precipitation.
• steel with low C + N content has a sufficiently high strength due to solute Ti when the amount of Ti addition is sufficiently excessive with respect to the C + N content.
• the fatigue limit showed higher fatigue characteristics in the group with lower C + N content, contrary to the tensile strength results. The reason for this is presumably that in the group with a high C + N content, the size of the precipitated carbonitride tends to be large, and the amount of the carbonitride is large, and this is the starting point for fatigue fracture.
• Fig. 10 shows the results of evaluation of magnetic properties by the Epstein method using the same number of magnetic test specimens cut from the rolling direction and the direction perpendicular to the rolling direction.
• the horizontal axis of the graph the amount in the steel Ti (mass%)
• the vertical axis is the frequency iron loss (W 10/1000) (W / kg)
• the iron loss characteristics of the group with a high C + .N content deteriorate rapidly when a small amount of Ti is added, while the iron loss due to the addition of Ti occurs in a group with a low C + N content.
• the deterioration was slight. From the above examination results, in order to obtain a non-oriented electrical steel sheet that satisfies the conflicting requirements such as industrially sufficiently good manufacturability, high strength considering fatigue strength and excellent magnetic properties at a high level Is to use Ti as an element that precipitates and fixes solute C and N, and as a solid solution strengthening element in a high alloy steel with the C + N content reduced as much as possible in the industry. It was discovered that is essential.
• C + N content is reduced to an industrially feasible level, and steel with an appropriate amount of carbonitride-forming elements (V, Nb, Zr) including Ti is added.
• V, Nb, Zr carbonitride-forming elements
• alloy elements such as Si, Mn, Al, Ni, and P, and clarified the optimum steel composition conditions.
• C and N are harmful elements that significantly reduce the productivity of steel when present in a solid solution state, but Ti or Nb, V described later (invention (3) '(4)).
• By adding an appropriate amount of carbonitride-forming elements such as Zr and Zr The impact can be reduced to a level that does not hinder production on an industrial scale. Nevertheless, carbonitride formation also leads to deterioration of magnetic properties and fatigue properties, so it is desirable to reduce C and N as much as possible. Therefore, C: 0.010% or less, N: 0.010% or less, and C + N ⁇ 0.010%.
• C and N do not need to be contained, but the lower limit for industrial reduction is about 0.0001%.
• Si is a major element that constitutes a non-oriented electrical steel sheet that has the effect of increasing the electrical resistance of steel and reducing iron loss.
• it has a high solid solution strengthening ability.
• the highest balance of high tensile strength, high fatigue strength and low iron loss In the present invention (1) ⁇ (2), it is added in an amount of 1.5% or more because it is an element that can be well balanced. More preferably, it is 2.0% or more.
• ⁇ (4) more than 3.5% is added positively, and high properties are obtained by increasing the tensile strength, fatigue limit strength and reducing iron loss, which is obtained with increasing Si content. Shall be utilized.
• the Si content exceeds 5.0%, the tensile strength increases, but the fatigue limit strength decreases rapidly, and the productivity decreases as cracks occur during cold rolling. This is thought to be due to the formation of ordered phases with increasing Si content.
• the Si content exceeds 3, the toughness starts to decrease, and when it exceeds 4.0%, the toughness deterioration clearly appears. Further, if it exceeds 5.0%, the toughness deteriorates remarkably, and a high degree of control is required at the time of threading and rolling, resulting in a decrease in productivity. Therefore, the upper limit of Si content was set to 5.0%. Preferably it is 4.0% or less. In the inventions (1) and (2), when the toughness is regarded as important, it is more preferably 3.5% or less.
• Ti is an important element in the present invention.
• Ti has the effect of increasing the recrystallization temperature of the steel, and even if the finish annealing temperature of the steel sheet is increased to 750 ° C or higher, a sufficiently unrecrystallized structure can be obtained in the present invention (1) (2). It has the effect of being able to remain.
• Ti acts as a solid solution strengthening element and contributes to higher tensile strength. In order to exhibit these effects stably, Ti: 0.05% or more and TiZ (C + N) ⁇ 16 are required. On the other hand, when Ti exceeds 0.8%, defects called “hege” tend to occur, and the manufacturability and yield are lowered. Therefore, the upper limit is set to 0.8%.
• Ti has the effect of improving the manufacturability of high-alloy steels by forming carbonitrides and precipitating and fixing solute C and N present in the steel. It also acts as a solid solution strengthening element and contributes effectively to high tensile strength and high fatigue strength.
• Ti + V is 0.05% or more.
• the upper limit of Ti + V is set to 0.8%.
• Nb and Zr also have the effect of improving the manufacturability of high-alloy steels by forming carbonitrides and precipitating and fixing solute C and N present in the steel, like Ti and V described above. ing. It also acts as a solid solution strengthening element and contributes effectively to high tensile strength and high fatigue strength. Therefore, in the present invention (3) '(4), these elements may be used in place of Ti and V.
• Nb + Zr In order to stably precipitate and fix C and N from the middle of the manufacturing process, it is necessary to contain at least 0.01% of the total Nb + Zr of Nb and Zr, and a sufficient excess of C and N (Nb + Zr) in mass% ratio / (C + N) ⁇ 10 was included in the range that satisfies. On the other hand, if Nb + Zr exceeds 0.5%, manufacturability decreases, so the upper limit of Nb + Zr is set to 0.5%. As described above, since Ti and V and Nb and Zr are the same as carbonitride-forming elements and solid solution strengthening elements, these four types can be combined and contained. .
• the total content of Ti, V, Nb, and Zr must be at least 0.01% of Ti + V + Nb + Zr. Mass, since it is necessary to add a sufficient excess to C and N. It is necessary to satisfy (Ti + V + Nb + Zr) / (C + N) ⁇ 1S in the / 0 ratio. However, if Ti + V + Nb + Zr exceeds 0.5%, manufacturability decreases, so the upper limit of Ti + V + Nb + Zr is 0.5%.
• Mn is an element effective for improving hot brittleness.
• Mn is added at 0.03% or more.
• the addition amount is limited to 3.0% or less.
• A1 increases the electrical resistance of steel and reduces iron loss. It is also effective for improving strength by solid solution strengthening. However, excessive addition causes a decrease in rollability, so the upper limit is made 3.0%. More preferably, it is 2.0% or less.
• ⁇ (2) which mainly uses strengthening by non-recrystallized structure, Si + Al ⁇ 4.0% is preferable.
• This A1 is not necessarily contained.
• the addition of A1 may be suppressed to 0.005% or less. That is, for example, A1 can be reduced by deoxidation with Si, while deposits such as A1N can be reduced to reduce iron loss.
• the lower limit of the amount of A1 in steel that can be industrially reduced is about 0.001%. • P: 0.2% or less
• P is extremely effective in increasing the strength, since a large solid solution strengthening ability can be obtained even in a relatively small amount, and is preferably added at 0.005% or more.
• the addition amount is limited to 0.2% or less, preferably 0.2% or less.
• the lower limit of the amount of P in steel that can be industrially reduced is about 0.001%.
• MnS may be the starting point for fatigue failure. For this reason, it is desirable to reduce the amount of S in the steel as much as possible, but if it is contained up to 0.01%, it is acceptable, so the amount added was made 0.01% or less. However, the lower limit of the amount of S in steel that can be industrially reduced is about 0.0003%.
• the basic composition of the non-oriented electrical steel sheet according to the present invention is as described above.
• Ni, Sb, Sn, B, Ca, rare earth elements (which are known as improving elements for magnetic properties) Rem) and Co can be added alone or in combination.
• these addition amounts should be such that the object of the present invention is not impaired.
• the range is as follows. Sb: 0.002 to 0.1%, Sn: 0.002—0.1%, B: 0.001—0.01%, Ca: 0.001 to 0.01%, Rem: 0.001 to 0.01%, Co: 0.2 to 5.0% and Ni: 5.0% or less, preferably 0.1 to 5.0%.
• Ni is suitable.
• many elements that contribute to solid solution strengthening and high electrical resistance lead to a decrease in saturation magnetic flux density due to their addition, whereas Ni does not decrease the saturation magnetic flux density, but strength due to solid solution strengthening.
• Ni is an expensive element and excessive addition causes cost, it is preferable to contain it at 5.0% or less.
• the balance of steel is Fe and inevitable impurities. Inevitable impurities include the elements listed above (if they are unavoidably contained for reasons such as cost). Or Cu (may be mixed when scrap steel is used as a raw material).
• the steel sheet structure be a recovered structure.
• the magnetic properties are extremely inferior.
• the recovery structure is formed by annealing at about 500 ° C or more, but this recovery structure has high strength and can obtain relatively good magnetic properties.
• this unrecrystallized recovered structure is the area in the cross-sectional observation of the steel sheet. It is necessary to have at least 50%.
• the production process from steel melting to cold rolling can be carried out in accordance with a method usually employed in general non-oriented electrical steel sheets.
• the appropriate plateauing and cold rolling properties of hot-rolled coils generally become a problem by appropriately controlling the amount of C and N and adding carbonitride-forming elements. Even in the case of high alloy steels having S i exceeding%, the manufacturability is greatly improved, so that the normal manufacturing process for non-oriented electrical steel sheets can be applied. Examples of typical production methods are given below. First, the molten steel melted to the specified components in a converter and secondary refinery, or an electric furnace is made into a steel slab by the continuous forging method or the ingot-making method.
• finishing temperature and the cutting temperature in the hot rolling do not need to be specified, and general conditions such as finishing rolling temperature: 700 ° C 900 ° C and Wheat removal temperature: 400 800 ° C is enough.
• hot-rolled sheet annealing can be performed at a temperature of about 600 1 lOOt for the purpose of softening the steel sheet or improving the magnetic properties of the final product.
• cold rolling or warm rolling is performed to obtain a predetermined product sheet thickness (final sheet thickness).
• the final sheet thickness may be obtained by one cold rolling or warm rolling, or the final sheet thickness is obtained by performing two or more cold rolling or warm rolling sandwiching intermediate annealing. Also good.
• the warm rolling is usually performed at a plate temperature of 100 30.0 ”.
• the final plate thickness is preferably 0.15 mm or more.
• the plate thickness has a large influence on the magnetic characteristics of the product, especially the iron loss characteristics in the high frequency range of several hundred Hz or more, which is important when used as a mouthpiece material for high-speed rotating motors. In this respect, it is more advantageous to reduce the plate thickness.
• the mechanical properties in the tensile test are hardly affected by the thickness, whereas the fatigue properties are from 0.15 mm. However, it decreased rapidly when it was thin.
• excessive thinning is also disadvantageous in terms of productivity in the motor manufacturing process due to an increase in press punching man-hours and an increase in the number of layers.
• the lower limit of the plate thickness be 0.15 mm.
• the upper limit of the plate thickness can be determined as appropriate according to the level of magnetic properties required, but generally less than 0.65 is generally used as a magnetic steel sheet.
• the deterioration of the magnetic properties due to the increase in strength is suppressed as compared with the conventionally known high-strength electrical steel sheet. Excellent magnetic properties can be obtained.
• finish annealing is performed in a continuous annealing furnace, and the annealing conditions are individually defined in Inventions (1) ⁇ (2) and Inventions (3) '(4).
• the unit tension of the steel strip (in the direction perpendicular to the threading plate, the so-called cross-sectional area in the TD direction) is maintained at a furnace tension of 2.5 MPa to 20 MPa.
• the annealing temperature is less than 700 ° C or the tension is less than 2.5 MPa
• the shape is not positive.
• the temperature exceeds 850 ° C recrystallization proceeds and the strength decreases.
• the furnace tension exceeds 20MPa the coil may be locally deformed and the shape may be deteriorated or the furnace may break, so the upper limit is 20MPa.
• more preferable operating ranges are a finish annealing temperature of 750 ° C to 850 ° C and a furnace tension of 5 MPa to 15 MPa.
• the annealing conditions such as the final annealing temperature so that the non-recrystallized recovery structure is secured by 50% or more in area ratio.
• the above annealing conditions substantially satisfy the requirements, but when the Ti content in the steel is less than 0.3%, the final annealing temperature T (° C) is roughly estimated from Fig.
• the finish annealing is performed within the annealing temperature range of 700 ° C to 1050 ° C. If the final annealing temperature is less than 700, recrystallization does not proceed sufficiently, and unrecrystallized grains increase unnecessarily, resulting in insufficient shape correction. Also, the magnetic properties are more stable and better at 700 ° C or higher. As the annealing temperature rises, the iron loss properties improve, but the mechanical properties (proof strength, tensile strength) and fatigue properties tend to decrease, so the annealing temperature is at the required magnetic property level and strength level.
• an insulating film is applied to the steel sheet by applying a treatment liquid and baking treatment to obtain a final product.
• a treatment liquid and baking treatment to obtain a final product.
• Types of insulating film ⁇ Film thickness and application conditions may be in the normal range.
• a phosphate-based film is preferably used.
• Steel slabs with the composition shown in Table 1 are hot-rolled to a thickness of 2.5 mm, then subjected to hot-rolled sheet annealing at 900 ° C for 60 s, and then pickling and cold-rolling to a thickness of 0.35 mm. Went.
• steel G whose Ti content exceeds the range of the present invention, had many defects after cold rolling, so the subsequent treatment was not performed.
• Steel N which has a high Si content of 4.3% and contains almost no Ti
• Steel P whose Si content exceeds the scope of the present invention, caused the plate to break during cold rolling. No processing was performed.
• finish annealing was performed under the conditions shown in Table 2 for a soaking time of 20 s.
• the in-furnace tension was measured with a tension meter roll-type in-furnace tension meter with a load cell built into the lower part of the bearing.
• IS5 was evaluated using IS5 tensile test pieces, and magnetic properties were evaluated by taking an equivalent amount of Epstein test pieces from the rolling direction and the perpendicular direction of rolling.
• the steel sheet was cut along the rolling direction, the thickness cross section was polished and the structure was observed, and the area ratio of the recrystallized structure was obtained.
• the area excluding the recrystallized portion was regarded as the recovery structure ratio.
• No. 6 15 17-; 19 32 35 38 and 40 which are invention examples using the steel having the steel composition of the present invention, exhibit high strength and low iron loss, and have a steel plate shape. But it ’s excellent.
• No. 38 in which the Si content in steel exceeds 40.0% and No. 38 in which the Si + Al content exceeds 0% has 27 and 23 bending properties after hot-rolled sheet annealing, respectively.
• all the other invention examples are 40 times or more, which is more excellent in manufacturability.
• the bending properties were evaluated by the number of times until cracking occurred in the steel sheet after repeated bending tests at a bending radius of 15 ⁇ and a bending angle of 90 ° at a temperature of 30 ° C.
• the steel A and D slabs in Table 1 are hot-rolled to a thickness of 2 mm, hot-rolled sheet annealed at 800 ° C for 60 s, pickled and cold-rolled to a thickness of 0.35.
• the coil was made.
• the obtained coil was subjected to tt-up annealing in a continuous annealing furnace under the conditions shown in Table 3, and the same evaluation as in Example 1 was performed.
• the steel slab having the composition shown in Table 4 was cold-rolled to the final plate thickness under any of the following conditions a to c.
• a hot-rolled annealed plate was cut into a width of 30 mm, a repetition bending test was performed at a temperature of 30 ° C, a bending radius of 15 mm, and a bending angle of 90 °, and a plate in the production line. Simulated sex was evaluated. In addition, as an evaluation of cold rollability, the depth of the edge cracks on the end face of the rolled sheet was measured.
• the mechanical properties (tensile strength TS), fatigue properties (fatigue limit strength FS) and magnetic properties (magnetic flux density B 5 o, high-frequency iron loss W 10/1 () () ) of the electrical steel sheet thus obtained were investigated. The results are shown in Table 7.
• the evaluation method for each property is as follows.
• Fatigue properties were determined by cutting out a test piece parallel to the rolling direction and polishing the end face of the parallel part with # 800 paper. After that, stress ratio: 0, 1, frequency: 20Hz partial tension (Tension-Tension) And evaluated with the maximum stress (fatigue limit strength FS) at which plate breakage does not occur even after 10 million (107) cycles.
• the magnetic properties were evaluated by collecting equal amounts of Epstein specimens from the rolling direction and the direction perpendicular to the rolling direction. ''
• a hot-rolled annealed sheet was cut out to a width of 30 mm, a bending radius: 15 mrn, a bending angle: 90 ° at ⁇ degree: 30, and a repeated bending test of 90 ° was performed to simulate the plate-through property in the production line. did.
• the depth of the edge cracks on the end face of the rolled plate was measured.
• a hot-rolled annealed plate (No.67 is a hot-rolled plate) was cut into a width of 30 mm, subjected to repeated bending tests at a temperature of 30, a bending radius of 15 mm, and a bending angle of 90 °.
• the edge crack depth of the rolled plate end face was measured.
• the high-frequency iron loss characteristics are greatly improved by reducing the plate thickness.
• the tensile strength is almost the same at any plate thickness.
• the present invention by restricting the component composition or the structure, it is possible to achieve high strength and excellent fatigue properties without adding restrictions or new processes in steel plate production [and plate shape and magnetic properties. A non-oriented electrical steel sheet with excellent characteristics can be obtained stably.

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