Classifications

• • 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
  • 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
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
• • 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
• • 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

Definitions

• FIG. 1 is a schematic diagram of a grain-oriented electrical steel sheet according to an embodiment of the present invention.
• FIG. 2 is a flow diagram illustrating a method for producing a grain-oriented electrical steel sheet according to an embodiment of the present invention.
• 3A and 3B are schematic diagrams of a grain-oriented electrical steel sheet according to one embodiment of the present invention.
• 4A and 4B are schematic diagrams of a grain-oriented electrical steel sheet according to one embodiment of the present invention.
• 5A and 5B are schematic diagrams of a grain-oriented electrical steel sheet according to one embodiment of the present invention.
• FIG. 6 is a diagram showing the relationship between groove depth and iron loss improvement rate in groove formation using only the laser method and groove formation using only the mechanical method.
• the grain-oriented electrical steel sheet 10 is a grain-oriented electrical steel sheet 10 in which a plurality of grooves extending in a direction substantially parallel to the width direction of the steel sheet are formed in the longitudinal direction of the steel sheet, and the plurality of grooves are formed from a first groove 20 in which no fine grains are formed at the bottom of the groove, and a second groove 30 in which fine grains are formed at the bottom of the groove.
• the fine grains are crystal grains whose size is reduced by partial machining or the like compared to the periphery of the bottom of the groove.
• the first groove 20 and the second groove 30 formed on the surface of the grain-oriented electromagnetic steel sheet 10 are each formed to extend parallel to the width direction of the steel sheet or in a direction that is slightly tilted from parallel, approximately parallel, for the purpose of improving the iron loss of the grain-oriented electromagnetic steel sheet 10.
• Approximately parallel can be in the range of 0 degrees or more and ⁇ 45 degrees or less, and typically may be in the range of 0 degrees or more and ⁇ 30 degrees or less. In reality, in order to avoid fractures or breaks and to balance the improvement of iron loss and the amount of B8 degradation, it may be in the range of +10 degrees or more and +20 degrees or less, or in the range of -20 degrees or more and -10 degrees or less.
• the first groove 20 can be formed by a non-contact groove forming method such as laser processing, etching, electron beam processing, plasma processing, etc.
• the first groove 20 can also be formed by a contact groove forming method such as machining, such as a press process in which a die with protrusions such as gears is pressed against the surface of the steel plate.
• the second groove 30 is formed by a contact groove forming method such as machining.
• subboundary factors mentioned above are factors that are the origin (cause) of subboundaries that generate subboundaries when exposed to a high-temperature environment.
• Subboundary factors are not yet subboundaries at the time the grooves are formed, and are not easy to confirm, but they become subboundaries that are easy to confirm by undergoing heat treatment at about 800°C, such as stress relief annealing.
• heat treatment at about 800°C, such as stress relief annealing.
• subboundary factors grow into subboundaries this is problematic as it can cause iron loss deterioration, but fine grains and subboundaries (including those generated by subboundary factors) disappear through aging when exposed to long periods of high temperatures (for example, 1000°C or higher), such as secondary recrystallization annealing.
• the first groove 20 since the first groove 20 is to be exposed to high temperatures for a long time after formation, the first groove 20 may be formed by a contact method such as machining or a non-contact method such as laser processing.
• a contact method such as machining or a non-contact method such as laser processing.
• the cold-rolled sheet (base steel) used to form the first groove 20 is harder than the steel sheet (grain-oriented electromagnetic steel sheet) after secondary recrystallization, it is more difficult to form deep grooves and the teeth are more likely to wear.
• the etching process does not generate subgrain boundary factors, there is no effect on iron loss deterioration due to subgrain boundary formation, but the manufacturing process and equipment are complicated and expensive.
• a grain-oriented electromagnetic steel sheet 10 that contains a mixture of a plurality of first grooves 20 in which fine grains and subgrain boundaries are not formed at the bottom of the groove portion, and a plurality of second grooves 30 in which fine grains are formed at the bottom of the groove portion.
• a grain-oriented electromagnetic steel sheet is manufactured having a plurality of first grooves 20 that have no fine grains or subgrain boundaries at the bottom and can be formed by utilizing the disappearance of fine grains, subgrain boundary factors, and subgrain boundaries at the bottom of the groove due to secondary recrystallization annealing, and a plurality of second grooves 20 that have fine grains at the bottom and can be formed by a contact method.
• This makes it possible to provide a grain-oriented electromagnetic steel sheet that achieves both improved iron loss and magnetic flux density. That is, the first grooves 20 do not have subgrain boundaries and subgrain boundary factors that cause iron loss deterioration.
• the method for manufacturing the grain-oriented electrical steel sheet 10 according to one embodiment of the present invention is a method for manufacturing the grain-oriented electrical steel sheet 10 in which a plurality of grooves extending in the longitudinal direction of the steel sheet and in a direction approximately parallel to the width direction of the steel sheet are formed.
• Figure 2 is a flow diagram illustrating the method for manufacturing the grain-oriented electrical steel sheet 10 according to one embodiment of the present invention.
• a first groove 20 consisting of a plurality of grooves extending in a direction approximately parallel to the width direction is formed in the cold-rolled steel sheet that is the material of the grain-oriented electromagnetic steel sheet 10 (first groove formation step).
• first groove formation step a plurality of first grooves 20 extending in a direction approximately parallel to the width direction of the steel sheet (cold-rolled steel sheet) are formed on the surface of the cold-rolled steel sheet that is the material of the grain-oriented electromagnetic steel sheet 10, which has been cast, hot-rolled, annealed, and cold-rolled and discharged from a finishing rolling mill, for magnetic domain control.
• the first groove 20 may be formed deeper than the second groove 30.
• Forming the first groove 20 deeper than the second groove 30 is effective in improving the iron loss of the grain-oriented electromagnetic steel sheet 10. It is preferable to use laser processing, which allows easy control of the depth direction and does not cause wear due to contact with the steel sheet, but as long as the method can ensure iron loss improvement, it is not limited to laser processing, and various methods such as various non-contact methods such as electron beam processing and plasma processing, and mechanical processing can be used to form the grooves.
• step S101 Once processing in step S101 is complete, proceed to step S102.
• step S102 the cold-rolled steel sheet with the first grooves 20 formed therein is annealed to align the magnetization easy axis of the cold-rolled steel sheet in the longitudinal direction of the steel sheet, thereby forming a grain-oriented electrical steel sheet (secondary recrystallization annealing step).
• the steel sheet having the first grooves 20 formed therein is subjected to decarburization annealing, for example, for a heating time of 1 to 3 minutes at a heating temperature of 700°C to 900°C.
• decarburization annealing the carbon concentration in the steel sheet is adjusted, and an oxide layer mainly made of silica (SiO 2 ) is formed on the surface of the decarburization annealed steel sheet.
• an annealing separator mainly made of magnesia (MgO) is applied to the oxide layer on the surface of the decarburization annealed steel sheet, and the steel sheet is wound into a coil.
• MgO magnesia
• the coiled grain-oriented electromagnetic steel sheet 10 is unwound to stretch it into a sheet, and while it is stretched, an insulating coating agent (coating liquid) is applied onto the glass coating formed on the surface of the grain-oriented electromagnetic steel sheet 10.
• the grain-oriented electromagnetic steel sheet 10 to which the insulating coating agent has been applied is annealed for a heating time of 10 to 120 seconds at a heating temperature of 800°C to 850°C to bake the insulating coating agent, thereby forming an insulating coating on the surface of the grain-oriented electromagnetic steel sheet 10 and imparting electrical insulation to the grain-oriented electromagnetic steel sheet 10 and a predetermined tension to the surface.
• the second groove 30 is formed by separate machining that does not easily deteriorate the magnetic flux density (magnetic flux density B8 is not easily deteriorated) by pushing the steel plate into the groove during groove formation and not losing the steel plate, thereby making it possible to achieve both iron loss improvement and magnetic flux density.
• a groove of 20 to 25 ⁇ m needs to be formed, and if this is performed in step S101, the magnetic properties (improved iron loss and avoidance of B8 degradation) cannot be obtained.
• the grain-oriented electromagnetic steel sheet 10 thus manufactured is shipped and used in any suitable industrial product, for example as a material for the iron core of a transformer.
• fine grains are present at the bottom of the second grooves 30 of the grain-oriented electrical steel sheet 10 (because they have not been exposed to high temperatures for a long period of time after groove processing), but at the bottom of the first grooves 20, there are no fine grains, subgrain boundaries, or subgrain boundary factors (because they have been exposed to high temperatures associated with secondary recrystallization annealing after groove processing).
• Figure 4 shows a schematic diagram of a grain-oriented electrical steel sheet according to one embodiment of the present invention.
• fine grains remain at the bottom of the groove corresponding to the second groove 30, while both the fine grains and the subgrain boundaries have disappeared at the bottom of the groove corresponding to the first groove 20, as shown in Figure 4B.
• FIG. 5 shows a schematic diagram of a grain-oriented electrical steel sheet according to one embodiment of the present invention.
• the formation pattern of the groove pitch, groove depth, groove angle, etc., when forming the second grooves 30 in the second groove formation step is not particularly limited, but may be, for example, as shown in FIG. 5. That is, as shown in FIG. 5A, on the surface of the steel sheet after the first grooves 20 described above with reference to FIG. 3A are formed in the material steel sheet, the second grooves 30 may be formed according to a formation pattern different from the formation pattern in which the first grooves 20 were formed, as shown in FIG. 5B.
• the second grooves 30 shown in FIG. 5B are formed by machining according to a second formation pattern with a groove pitch of 5 mm, a groove depth of 10 ⁇ m, and a groove angle of -12 degrees.
• Fig. 6 is a diagram showing the relationship between the groove depth and the iron loss improvement rate in the case of groove formation by the laser method alone and groove formation by the mechanical method alone
• Fig. 7 is a diagram showing the relationship between the groove depth and the B8 deterioration amount in the case of groove formation by the laser method alone and groove formation by the mechanical method alone.
• the B8 degradation amount is 300 gauss or more.
• the non-contact laser method allows for the formation of relatively deep grooves, which generates leakage flux from the surface magnetic pole and increases magnetostatic energy, making it easier to subdivide the main magnetic domain and improve iron loss; on the other hand, the magnetic flux density B8 increases the volume (amount) of steel plate base material that is removed, which is thought to increase the amount of degradation.
• the deterioration in magnetic flux density B8 is less than 200 gauss at a groove depth of 15 to 20 ⁇ m, but an iron loss improvement rate of 11% or more cannot be achieved.
• the reason for the poor iron loss improvement rate is that with contact groove formation, it is difficult to form deep grooves due to wear of the tooth profile and chipping of the blade.
• the reason for the good magnetic flux density B8 is thought to be that, as can be seen from the generation of fine grains, the base material of the steel plate is pushed into the bottom of the groove, minimizing the loss of the base material of the steel plate.
• the first groove 20 is formed by laser processing according to a first forming pattern with a scan speed of 45 m/s, a groove pitch of 3 mm, a beam shape of 25 x 50 ⁇ m, and groove depths of 0 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, and 25 ⁇ m by adjusting the laser power.
• the second groove 30 is formed by press processing according to a second forming pattern with a groove pitch of 5 mm, and groove depths of 0 ⁇ m, 10 ⁇ m, 15 ⁇ m, and 20 ⁇ m by adjusting the pressure force of the tooth profile.
• FIG. 8 is a diagram showing the iron loss improvement rate by combining a laser method and a mechanical method according to one embodiment of the present invention.
• FIG. 9 is a diagram showing the relationship between the groove depth and the iron loss improvement rate for each combination according to one embodiment of the present disclosure.
• the grain-oriented electromagnetic steel sheet 10 of this embodiment which has a mixture of first grooves 20 formed by laser processing and second grooves 30 formed by press processing
• the relationship between various combinations of groove depth by laser processing and groove depth by press processing and the iron loss improvement rate is the experimental results shown in FIG. 8 and FIG. 9.
• the combinations that achieved an iron loss improvement rate of 11% or more are the seven combinations highlighted in FIG. 8.
• FIG. 10 is a diagram showing the amount of B8 degradation by a combination of a laser method and a mechanical method according to one embodiment of the present invention.
• FIG. 11 is a diagram showing the relationship between the groove depth and the amount of B8 degradation for each combination according to one embodiment of the present invention. The relationship between various combinations of groove depth by laser processing and groove depth by press processing and the iron loss improvement rate is the experimental results shown in FIG. 10 and FIG. 11.
• the amount of B8 degradation is 200 gauss or less in three combinations: a combination of a laser processing groove depth of 10 ⁇ m and a press processing groove depth of 15 ⁇ m (amount of B8 degradation 180 gauss), a combination of a laser processing groove depth of 15 ⁇ m and a press processing groove depth of 5 ⁇ m (amount of B8 degradation 170 gauss), and a combination of a laser processing groove depth of 15 ⁇ m and a press processing groove depth of 10 ⁇ m (amount of B8 degradation 200 gauss).
• a similar groove depth may also be formed by electron beam or plasma processing, which are similar thermal processes.
• the groove depth can be controlled by adjusting the accelerating voltage and current in the case of electron beams, and by adjusting the output current in the case of plasma.

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Citations (9)

• 2024
  • 2024-09-27 CN CN202480060043.0A patent/CN121889518A/zh active Pending
  • 2024-09-27 JP JP2025510402A patent/JPWO2025079437A1/ja active Pending
  • 2024-09-27 WO PCT/JP2024/034626 patent/WO2025079437A1/ja active Pending

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