A thick-gauge high-strength low-coercivity non-oriented electrical steel and a method for manufacturing the same

Abstract

The application discloses a kind of thick gauge high-strength low-coercivity non-oriented electrical steel and preparation method thereof, belong to cold-rolled non-oriented electrical steel field.Steel component is as follows according to percentage by weight: C≤0.005%, Si is 1.8%~2.4%, Mn is 0.18%~0.8%, Al is 0.15%~0.8%, S≤0.01%, P≤0.03%, N≤0.005%, Nb≤0.005%, V≤0.01%, Ti≤0.01%, Ni≤0.1, Cr≤0.1%, the rest is Fe and inevitable residual element;The process is as follows: hot metal pretreatment→converter smelting→RH refining→continuous casting→hot rolling→normalizing→pickling→cold rolling→continuous annealing→rewinding.The application has excellent mechanical properties, electromagnetic polarization intensity performance, coercive force performance, low iron loss performance.

Description

Technical Field

[0001] This invention relates to the field of cold-rolled non-oriented electrical steel, specifically to a thick-gauge high-strength low-coercivity non-oriented electrical steel and its preparation method. Background Technology

[0002] An electromagnetic switch is a switch controlled by an electromagnet; it's a combination of an electromagnet and a switch. When the electromagnet coil is energized, it generates electromagnetic attraction, causing the movable iron core to push or pull the switch contacts to close, thus connecting the controlled circuit. The iron core of an electromagnetic switch needs to possess high electromagnetic attraction, rapid demagnetization, and high reliability, while also exhibiting a certain degree of energy efficiency.

[0003] Therefore, non-oriented electrical steel used in electromagnetic switch cores needs to have high magnetic polarization intensity to increase electromagnetic attraction; low coercivity to improve demagnetization performance and reduce switch disconnection time; high yield strength and thickness to improve the reliability of the core in frequent collisions; low iron loss for excellent energy-saving performance; and low hardness to improve the service life of the mold.

[0004] Conventional non-oriented electrical steels generally strive for excellent electromagnetic properties, which requires sufficient grain growth. This results in lower mechanical strength and poor resistance to deformation, leading to lower impact resistance in electromagnetic switch cores.

[0005] The standard thickness range of non-oriented electrical steel sheets is 0.3-0.65mm. Non-oriented electrical steel sheets of this thickness are prone to deformation after being stacked and subjected to impact, making it difficult to guarantee the performance requirements of electromagnetic switch cores for high-frequency impacts. To improve the impact resistance of electromagnetic switch cores, the material thickness needs to be increased.

[0006] The non-oriented electrical steel production line is designed to produce silicon steel with a thickness of 0.3-0.65mm. A thickness of 1.0mm exceeds the production line's design capacity. The steel plate is too thick, resulting in low cooling efficiency after annealing, which can easily lead to high plate temperature at the furnace exit, scalding of the rubber rollers after the furnace, insufficient tension of the inlet looper, which can easily cause deviation, and insufficient winding tension, which can easily cause uneven winding. Summary of the Invention

[0007] To address the above problems, this invention provides a non-oriented electrical steel with thick, high-strength, and low-coercivity properties, and its preparation method. The prepared steel plate is mainly used in the core of electromagnetic switches. It has thick dimensions and high strength, which improves the impact resistance of electromagnetic switch products, thereby increasing the mechanical life of electromagnetic switches; it also has low coercivity properties, which shortens the disconnection time of electromagnetic switches.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A non-oriented electrical steel with high strength and low coercivity in thick gauge, wherein the chemical composition of the non-oriented electrical steel by weight percentage is: C≤0.005%, Si 1.8%~2.4%, Mn 0.18%~0.8%, Al 0.15%~0.8%, S≤0.01%, P≤0.03%, N≤0.005%, Nb≤0.005%, V≤0.01%, Ti≤0.01%, Ni≤0.1%, Cr≤0.1%, with the remainder being Fe and unavoidable residual elements.

[0010] The preparation method of the above-mentioned non-oriented electrical steel with thick gauge, high strength, and low coercivity properties, comprises the following process flow: hot metal pretreatment → converter smelting → RH refining → continuous casting → hot rolling → normalizing → pickling → cold rolling → continuous annealing unit → recoiling → packaging. Specifically, it includes the following steps:

[0011] (1) Through hot metal pretreatment, converter smelting, and RH refining, the steel composition is brought into control.

[0012] C≤0.005%, Si 1.8%–2.4%, Mn 0.18%–0.8%, Al 0.15%–0.8%, S≤0.01%, P≤0.03%, N≤0.005%, Nb≤0.005%, V≤0.01%, Ti≤0.01%, Ni≤0.1%, Cr≤0.1%, with the remainder being Fe and unavoidable residual elements.

[0013] C affects magnetic properties; reducing C content helps prevent magnetic aging and reduce iron loss.

[0014] Si is a strengthening element that reduces iron loss, lowers coercivity, and significantly improves hardness and strength.

[0015] Mn is a strengthening element that forms MnS with S, which coarsens MnS, promoting grain growth, reducing iron loss, reducing coercivity, improving stamping properties, improving machinability, and increasing strength and hardness.

[0016] Al is a strengthening element that forms AlN with N, reducing iron loss, reducing coercivity, and increasing hardness and strength.

[0017] The phosphorus content should be controlled to ≤0.03% to prevent embrittlement.

[0018] Smelting controls reduce the content of Ni, Cr, Ti, Nb, V, S and N elements.

[0019] Ni and Cr are not beneficial elements, and their content in molten iron is controlled.

[0020] Ti, Nb, V, S, and N are harmful elements that improve the purity of steel and increase magnetic polarization.

[0021] (2) Continuous casting: Electromagnetic stirring is used to make the proportion of equiaxed crystals ≥40%. The increase in the proportion of equiaxed crystals improves the electromagnetic performance.

[0022] (3) Hot rolling: The slab is hot-charged into a continuous heating furnace at a charging temperature ≥380℃ to prevent internal cracking of the cast slab. The heating temperature is 1000~1250℃, the heating time is ≥160min, and the furnace exit temperature is 1100~1170℃ to prevent AlN and Mns precipitates from re-solidifying during heating and dispersing after hot rolling, thus hindering grain growth after hot rolling and during annealing. The roughing rolling temperature is 950~1020℃, the finishing rolling temperature is 830~900℃, and the coiling temperature is 650~720℃ to make the grains larger after normalizing. The rolling thickness is 2.0~3.0mm to increase the thickness of the hot-rolled plate, increase the compression ratio, increase the rolling tension, improve the stability of rolling operation, and prevent rolling deviation.

[0023] (4) The average heating temperature for normalization is 900-1000℃, and the heating time is 3-5 minutes. This increases the number of recrystallized grains, makes the structure more uniform, improves electromagnetic properties, and prevents corrugation defects.

[0024] (5) After pickling, the steel plate is cold rolled to a thickness of 1.0±0.05mm to improve its resistance to deformation.

[0025] (6) Continuous annealing: The continuous annealing unit controls the heating temperature of the soaking section in the process section to 780-860℃, and the soaking time to 1.2-2.2min, controlling the mechanical and electromagnetic properties. The annealing unit controls the looper extraction and filling speed to ≤100m / min, controls the looper quantity to ≤70%, and prevents looper deviation; controls the cooling fan output, controls the furnace exit plate temperature to ≤90℃, and prevents the rubber rollers after the furnace from being scalded; the outlet water spray is turned off to prevent water droplets from falling onto the strip surface and causing corrosion; the drying furnace temperature is ≤500℃, and the drying furnace outlet fan is normally engaged to keep the continuous annealing coiling temperature ≤60℃, preventing the bending stress from decreasing and the bending deformation from increasing, and keeping the residual curvature of the steel plate ≤70mm; the coiling unit tension is controlled to 13.5-20N / mm. 2 This ensures that the winding edges are neat and that no tower coiling occurs.

[0026] (7) Rewinding: The rewinding unit controls the unit tension of winding to be 13.5~22N / mm. 2 To prevent insufficient tension, which would result in uneven winding of the steel coil edges, and excessive tension, which would cause wear on the coil shaft due to excessive tension, the winding aid should wrap around the coil at least 10 times before unwinding, without stopping the machine during this process. The lead should begin winding at a low speed, below 50 m / min, and then increase the speed to 150-300 m / min after winding more than 50 m, ensuring the steel coil edges are neatly wound.

[0027] This invention can improve the purity of steel, control the normalizing process parameters, and increase the magnetic polarization intensity; it can control iron loss, coercivity, and mechanical properties by controlling the chemical composition of steel, hot rolling, normalizing, and annealing process parameters; it can control strip deviation and improve the same-plate difference by increasing the hot rolling thickness, increasing the compression ratio, and increasing the rolling force; it can control the steel plate thickness by controlling the mill roll gap; it can control the furnace exit plate temperature by controlling the cooling fan output; it can control strip deviation by controlling the inlet looper withdrawal and filling amount and filling speed; and it can prevent uneven strip coiling by increasing the coiling tension and controlling the coiling speed and length of the strip head.

[0028] The beneficial effects of this invention are:

[0029] (1) It has excellent mechanical properties and a thickness of 1±0.05mm, a hardness HV1 of 140~170, and a yield strength R p0.2 With a strength of 280–360 MPa and a tensile strength Rm of 430–510 MPa, the electromagnetic switch core is protected from deformation and damage during frequent impacts, enabling it to withstand more than 10 million impact cycles.

[0030] (2) It has excellent electromagnetic polarization intensity performance, J 2500 ≥1.56T, J 5000 ≥1.66T, which gives the electromagnetic switch a strong electromagnetic attraction force during operation.

[0031] (3) It has excellent coercivity performance, Hc≤60A / m, shortens the demagnetization time, and improves the timeliness of power-off of electromagnetic switches during operation.

[0032] (4) It has certain low iron loss performance, P 1.5 / 50 ≤8W / Kg, saving energy consumption of electromagnetic switches during operation.

[0033] (5) The rolling process was stable, with no deviation in the strip rolling process. The rolling thickness was controlled stably, and the steel plate thickness was controlled within the range of 1.0±0.03mm.

[0034] (6) The strip at the inlet of the continuous annealing unit runs stably without any strip deviation or scraping; the rubber rollers after the continuous annealing furnace are not scalded; no water droplets on the strip surface cause corrosion; the residual curvature of the steel plate is ≤70mm; the edges of the steel coils are neatly rolled and there are no tower coil problems.

[0035] (7) The edges of the re-coiled steel coil are neatly wound. Detailed Implementation

[0036] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0037]

Example 1

[0038] A method for preparing a thick-gauge, high-strength, low-coercivity non-oriented electrical steel specifically includes the following steps:

[0039] 1.1 Chemical composition of the product (wt%)

[0040] The carbon content was controlled through hot metal pretreatment, converter smelting, and vacuum refining decarburization: C: 0.0017; Si: 2.1876; Mn: 0.2885; P: 0.01125; S: 0.0022; Al: 0.3145; N: 0.001; Nb: 0.0018; Ti: 0.0016; V: 0.002; Ni: 0.0041; Cr: 0.0231; with the remainder being Fe and unavoidable residual elements.

[0041] 1.2 Electromagnetic stirring was used to control the equiaxed crystal ratio to 58%.

[0042] 1.3 Continuous hot-charging furnace for slabs; charging temperature 450℃, three-stage heating temperatures 1173℃, 1235℃, and 1171℃ respectively, heating time 215 min, exit temperature 1121℃, roughing end temperature 973℃, finishing end temperature 856℃, coiling temperature 671℃. Rolling specification 2.3mm.

[0043] 1.4 The normalization average thermal temperature was 971℃, and the heating time was 4.7 min.

[0044] 1.5 After pickling, cold rolling is performed to a thickness of 1.0±0.03mm.

[0045] 1.6 The continuous annealing coating unit's control process includes: a soaking zone heating temperature of 816℃; a soaking time of 1.5 min; a looper extraction and filling speed of 90 m / min; a looper fill rate of 65%; an outlet plate temperature of 78℃; an outlet water spray system shut off; a maximum drying oven temperature of 316℃; normal operation of the drying oven outlet fan; a winding temperature of 48℃; a winding tension of 20 kN; and a winding unit tension of 16.26 N / mm. 2 .

[0046] The 1.7 rewinding unit controls the winding tension at 20 kN, with a unit winding tension of 16.67 N / mm. 2 The number of turns of the steel coil wrapped by the winding aid is controlled to be 12 before unwinding, without stopping the machine during this process. The winding speed of the lead winding is 25m / min, and after winding 60m, the speed is increased to 200m / min.

[0047] 1.8 Product Testing and Performance: Magnetic Polarization J 2500 It is 1.62T, J 5000 It is 1.711T; iron loss P 1.5 / 50It is 6.34 W / kg; tensile strength R m 478 MPa; yield strength R p0.2 The strength is 321 MPa; the hardness HV1 is 157; and the coercivity Hc is 53.22 A / m.

[0048]

Example 2

[0049] A method for preparing a thick-gauge, high-strength, low-coercivity non-oriented electrical steel specifically includes the following steps:

[0050] 1.1 Chemical composition of the product (wt%)

[0051] The carbon content was controlled through hot metal pretreatment, converter smelting, and vacuum refining decarburization: C: 0.0024; Si: 2.1367; Mn: 0.5238; P: 0.01245; S: 0.0028; Al: 0.3012; N: 0.0011; Nb: 0.0012; Ti: 0.0027; V: 0.0019; Ni: 0.0039; Cr: 0.01184; the others being Fe and unavoidable residual elements.

[0052] 1.2 Continuous casting: Electromagnetic stirring is used to control the equiaxed crystal ratio at 51%.

[0053] 1.3 Continuous hot-charging furnace for slabs; charging temperature 430℃, three-stage heating temperatures 1158℃, 1230℃, and 1160℃ respectively, heating time 221 min, exit temperature 1111℃, roughing rolling termination temperature 972℃, finishing rolling final temperature 850℃, coiling temperature 665℃. Rolling specification 2.6mm.

[0054] 1.4 The normalization average thermal temperature was 953℃, and the heating time was 4.7 min.

[0055] 1.5 After pickling, cold rolling is performed to a thickness of 1.0±0.03mm.

[0056] 1.6 Continuous annealing coating unit; heating temperature of the soaking zone in the control process section: 833℃; soaking time: 1.5min; looper extraction and filling speed: 85m / min; looper volume: 68%; outlet plate temperature: 81℃; outlet water spray: closed; maximum drying oven temperature: 426℃; drying oven outlet fan: normally activated; winding temperature: 50℃; winding tension: 19KN; unit winding tension: 18.1N / mm 2 .

[0057] 1.7 The rewinding unit controls the winding tension at 19 kN, with a unit winding tension of 19 N / mm. 2The number of turns of the steel coil wrapped by the winding aid is controlled to be 14 before unwinding, without stopping the machine during this process. The winding speed of the lead winding is 30m / min, and after winding 65m, the speed is increased to 220m / min.

[0058] 1.8 Product Testing and Performance: Magnetic Polarization J 2500 It is 1.626T, J 5000 It is 1.717T; iron loss P 1.5 / 50 It is 6.24 W / kg; tensile strength R m 481 MPa; yield strength R p0.2 The strength is 326 MPa; the hardness HV1 is 153; and the coercivity Hc is 48.52 A / m.

[0059]

Example 3

[0060] A method for preparing a thick-gauge, high-strength, low-coercivity non-oriented electrical steel specifically includes the following steps:

[0061] 1.1 Chemical composition of the product (wt%)

[0062] The carbon content was controlled through hot metal pretreatment, converter smelting, and vacuum refining decarburization: C: 0.0024; Si: 2.1367; Mn: 0.5238; P: 0.01245; S: 0.0028; Al: 0.3012; N: 0.0011; Nb: 0.0012; Ti: 0.0027; V: 0.0019; Ni: 0.0039; Cr: 0.01184; the others being Fe and unavoidable residual elements.

[0063] 1.2 Continuous casting: Electromagnetic stirring is used to control the equiaxed crystal ratio at 49%.

[0064] 1.3 Continuous hot-charging furnace for slabs; charging temperature 421℃, three-stage heating temperatures 1158℃, 1230℃, and 1160℃ respectively, heating time 218 min, exit temperature 1109℃, roughing rolling termination temperature 971℃, finishing rolling final temperature 843℃, coiling temperature 658℃. Rolling specification 2.6mm.

[0065] 1.4 The normalization average thermal temperature was 948℃, and the heating time was 4.7 min.

[0066] 1.5 After pickling, the material is cold-rolled to a thickness of 1.0±0.02mm.

[0067] 1.6 Continuous annealing coating unit; heating temperature of the soaking zone in the control process section: 825℃; soaking time: 1.5min; looper extraction and filling speed: 82m / min; looper quantity: 63%; outlet plate temperature: 80℃; outlet water spray: closed; maximum drying oven temperature: 315℃; drying oven outlet fan: normally activated; winding temperature: 46℃; winding tension: 20KN; unit winding tension: 19.05N / mm 2 .

[0068] 1.7 The rewinding unit controls the winding tension at 19 kN, with a unit winding tension of 19 N / mm. 2 The number of turns of the steel coil wrapped by the winding aid is controlled to be 15 before unwinding, without stopping the machine during this process. The winding speed of the lead winding is 35m / min, and after winding 60m, the speed is increased to 240m / min.

[0069] 1.8 Product Testing and Performance: Magnetic Polarization J 2500 It is 1.626T, J 5000 It is 1.717T; iron loss P 1.5 / 50 It is 6.17 W / kg; tensile strength R m 476 MPa; yield strength R p0.2 The strength is 318 MPa; the hardness HV1 is 152; and the coercivity Hc is 51.27 A / m.

[0070]

Example 4

[0071] A method for preparing a thick-gauge, high-strength, low-coercivity non-oriented electrical steel specifically includes the following steps:

[0072] 1.1 Chemical composition of the product (wt%)

[0073] The carbon content was controlled through hot metal pretreatment, converter smelting, and vacuum refining decarburization: C: 0.0029; Si: 1.9531; Mn: 0.1941; P: 0.0108; S: 0.003; Al: 0.284; N: 0.003; Nb: 0.002; Ti: 0.002; V: 0.002; Ni: 0.005; Cr: 0.0107; with the remainder being Fe and unavoidable residual elements.

[0074] 1.2 Continuous casting: Electromagnetic stirring is used to control the equiaxed crystal ratio at 51%.

[0075] 1.3 Continuous hot-charging furnace for slabs; charging temperature 451℃, three-stage heating temperatures 1175℃, 1238℃, and 1173℃ respectively, heating time 245 min, exit temperature 1125℃, roughing rolling termination temperature 985℃, finishing rolling final temperature 877℃, coiling temperature 696℃. Rolling specification 2.3mm.

[0076] 1.4 The normalization average thermal temperature was 961℃, and the heating time was 4.2 min.

[0077] 1.5 After pickling, cold rolling is performed to a thickness of 1.0±0.03mm.

[0078] 1.6 Continuous annealing coating unit; heating temperature of the soaking zone in the control process section: 805℃; soaking time: 1.8min; looper extraction and filling speed: 84m / min; looper quantity: 67%; outlet plate temperature: 72℃; outlet water spray: closed; maximum drying oven temperature: 338℃; drying oven outlet fan: normally activated; winding temperature: 45℃; winding tension: 20KN; unit winding tension: 19.05N / mm 2 .

[0079] 1.7 The rewinding unit controls the winding tension at 20 kN, with a unit winding tension of 20 N / mm. 2 The number of turns of the steel coil wrapped by the winding aid is controlled to be 15 before unwinding, without stopping the machine during this process. The winding speed of the lead winding is 25m / min, and after winding 60m, the speed is increased to 250m / min.

[0080] 1.8 Product Testing and Performance: Magnetic Polarization J 2500 It is 1.626T, J 5000 It is 1.717T; iron loss P 1.5 / 50 It is 6.76 W / kg; tensile strength R m 467 MPa; yield strength R p0.2 The strength is 303 MPa; the hardness HV1 is 147; and the coercivity Hc is 52.29 A / m.

[0081]

Example 5

[0082] A method for preparing a thick-gauge, high-strength, low-coercivity non-oriented electrical steel specifically includes the following steps:

[0083] 1.1 Chemical composition of the product (wt%)

[0084] The carbon content was controlled through hot metal pretreatment, converter smelting, and vacuum refining decarburization: C: 0.0018; Si: 2.117; Mn: 0.202; P: 0.0158; S: 0.003; Al: 0.384; N: 0.003; Nb: 0.003; Ti: 0.004; V: 0.003; Ni: 0.006; Cr: 0.0285; with the remainder being Fe and unavoidable residual elements.

[0085] 1.2 Continuous casting: Electromagnetic stirring is used to control the proportion of equiaxed crystals to 53%.

[0086] 1.3 Continuous hot-charging furnace for slabs; charging temperature 405℃, three-stage heating temperatures 1135℃, 1225℃, and 1159℃ respectively, heating time 255 min, exit temperature 1109℃, roughing rolling termination temperature 969℃, finishing rolling final temperature 871℃, coiling temperature 688℃. Rolling specification 2.3mm.

[0087] 1.4 The normalization average thermal temperature was 981℃, and the heating time was 4.2 min.

[0088] 1.5 After pickling, cold rolling is performed to a thickness of 1.0±0.03mm.

[0089] 1.6 Continuous annealing coating unit; heating temperature of the soaking zone in the control process section: 821℃; soaking time: 1.8min; looper extraction and filling speed: 85m / min; looper quantity: 65%; furnace exit plate temperature: 74℃; outlet water spray: closed; maximum drying oven temperature: 258℃; drying oven outlet fan: normally activated; winding temperature: 47℃; winding tension: 20KN; unit winding tension: 19.05N / mm 2 .

[0090] 1.7 The rewinding unit controls the winding tension at 21 kN, with a unit winding tension of 21 N / mm. 2 The number of turns of the steel coil wrapped by the winding aid is controlled to be 16 before it is unwound, without stopping the machine during this process. The winding speed of the lead winding device is 30m / min, and after winding 55m, the speed is increased to 220m / min.

[0091] 1.8 Product Testing and Performance: Magnetic Polarization J 2500 It is 1.61T, J 5000 It is 1.701T; iron loss P 1.5 / 50 It is 6.9 W / kg; tensile strength R m 465 MPa; yield strength R p0.2 The strength is 310 MPa; the hardness HV1 is 155; and the coercivity Hc is 43.59 A / m.

[0092]

Example 6

[0093] A method for preparing a thick-gauge, high-strength, low-coercivity non-oriented electrical steel specifically includes the following steps:

[0094] 1.1 Chemical composition of the product (wt%)

[0095] The carbon content was controlled through hot metal pretreatment, converter smelting, and vacuum refining decarburization: C: 0.0029; Si: 2.2502; Mn: 0.3495; P: 0.0095; S: 0.0038; Al: 0.369; N: 0.002; Nb: 0.001; Ti: 0.002; V: 0.002; Ni: 0.004; Cr: 0.01264; the others were Fe and unavoidable residual elements.

[0096] 1.2 Continuous casting: Electromagnetic stirring is used to control the proportion of equiaxed crystals to 50%.

[0097] 1.3 Continuous hot-charging furnace for slabs; charging temperature 448℃, three-stage heating temperatures 1178℃, 1240℃, and 1175℃ respectively, heating time 183 min, exit temperature 1139℃, roughing end temperature 1005℃, finishing end temperature 886℃, coiling temperature 705℃. Rolling specification 2.6mm.

[0098] 1.4 The normalization average thermal temperature was 932℃, and the heating time was 4.2 min.

[0099] 1.5 After pickling, cold rolling is performed to a thickness of 1.0±0.03mm.

[0100] 1.6 Continuous annealing coating unit; heating temperature of the soaking zone in the controlled process section: 791℃; soaking time: 1.4min; looper extraction and filling speed: 80m / min; looper quantity: 68%; furnace exit plate temperature: 75℃; outlet water spray: closed; maximum drying oven temperature: 252℃; drying oven outlet fan: normally activated; winding temperature: 46℃; winding tension: 20KN; winding unit tension: 19.05N / mm 2 .

[0101] 1.7 The rewinding unit controls the winding tension at 20 kN, with a unit winding tension of 20 N / mm. 2 The number of turns of the steel coil wrapped by the winding aid is controlled to be 18 before unwinding, without stopping the machine during this process. The winding speed of the lead winding is 32m / min, and after winding 65m, the speed is increased to 240m / min.

[0102] 1.8 Product Testing and Performance: Magnetic Polarization J 2500 It is 1.617T, J 5000 It is 1.708T; iron loss P 1.5 / 50 It is 6.53 W / kg; tensile strength R m 482 MPa; yield strength R p0.2 The strength is 339 MPa; the hardness HV1 is 160; and the coercivity Hc is 55.3 A / m.

Claims

1. A thick-gauge, high-strength, low-coercivity non-oriented electrical steel, characterized in that, The chemical composition of the non-oriented electrical steel, by weight percentage, is: C≤0.005%, Si 1.8%~2.4%, Mn 0.18%~0.8%, Al 0.15%~0.8%, S≤0.01%, P≤0.03%, N≤0.005%, Nb≤0.005%, V≤0.01%, Ti≤0.01%, Ni≤0.1%, Cr≤0.1%, with the remainder being Fe and unavoidable residual elements; The thickness of the non-oriented electrical steel is 1.0±0.05mm; The non-oriented electrical steel has a magnetic polarization strength J 2500 ≥ 1.56 T, a coercivity Hc 5000 ≤ 60 A / m, a loss P 1.5 / 50 ≤ 8 W / Kg, a yield strength R p0.2 of 280-360 MPa, a tensile strength Rm of 430-510 MPa, and a hardness HV1 of 140-170.

2. The method for preparing the non-oriented electrical steel according to claim 1, characterized in that, The process flow is as follows: molten iron pretreatment → converter smelting → RH refining → continuous casting → hot rolling → normalizing → pickling → cold rolling → continuous annealing → recoiling, specifically including the following steps: (1) Controlling steel composition through hot metal pretreatment, converter smelting and RH refining; (2) Continuous casting: Electromagnetic stirring is used to control the proportion of equiaxed crystals to ≥40%; (3) Hot rolling: The slab is hot-charged into a continuous heating furnace with a charging temperature ≥380℃, a heating temperature of 1000~1200℃, a heating time ≥160 min, and an exit temperature of 1100~1170℃; the roughing rolling temperature is 950~1020℃, the finishing rolling temperature is 830~900℃, and the coiling temperature is 650~720℃; the rolling thickness is 2.0~3.0mm. (4) Normalizing heating temperature 900~1000℃, heating time 3~5min; (5) After pickling, the thickness is cold rolled to 1.0±0.05mm; (6) Continuous annealing: The heating temperature of the soaking zone is 780~860℃, and the soaking time is 1.2~2.2min; the temperature of the plate exiting the furnace is controlled to be ≤90℃; (7) Rewind.

3. The preparation method according to claim 2, characterized in that, In step (6), during the annealing process, the inlet looper extraction and filling speed is controlled to be ≤100m / min, the looper quantity is controlled to be ≤70%, the outlet plate temperature is controlled to be ≤90℃, the outlet water spray cooling is turned off, the drying furnace temperature is ≤500℃, the drying furnace outlet fan is normally activated, the winding temperature is controlled to be ≤60℃, and the winding unit tension is controlled to be 13.5~20N / mm. 2 .

4. The preparation method according to claim 2, characterized in that, In step (7), during the rewinding process, the unit tension during winding is controlled to be 13.5-22 N / mm. 2 After the winding aid has wrapped and wound the steel coil more than 10 times, it is then opened. During this process, the machine must not be stopped. The winding should be carried out at a low speed, with the winding speed controlled below 50m / min. After winding more than 50m, the speed is increased to 150-300m / min.