Method for manufacturing stress-relief-annealing-resistant, low-iron-loss grain-oriented silicon steel

Abstract

Disclosed is a method for manufacturing stress-relief-annealing-resistant, low-iron-loss grain-oriented silicon steel, the method comprising: carrying out, by means of a pulse laser, scanning grooving on a single surface or two surfaces of a silicon steel sheet after cold rolling, or after decarburizing annealing, or after high temperature annealing or after hot stretching, temper rolling and annealing, and forming several grooves parallel with each other in a rolling direction of the silicon steel sheet, wherein a single pulse time width of the pulse laser is 100 ns or less, and a single pulse peak energy density is 0.05 J/cm.sup.2 or more; the energy density of a single scan of a single laser beam is 1 J/cm.sup.2 to 100 J/cm.sup.2; a beam spot of the pulse laser is a single beam spot or a combination of a plurality of beams spots, the shape of the beam spot is circular or elliptic, and the diameter of the beam spot in a scanning direction is 5 μm to 1 mm, and the diameter thereof in a direction perpendicular to the scanning direction is 5 μm to 300 μm; and when scanning grooving is carried out at the same position on the silicon steel sheet, the product of the number of beam spots of the pulse laser and the scan times is 5 or more.

Claims

1. A method for manufacturing stress-relief-annealing-resistant, low-iron-loss grain-oriented silicon steel, comprising: subjecting silicon steel to iron smelting, steel smelting, continuous casting, hot rolling, single or double cold rolling, followed by decarburization annealing, coating a MgO-based separation agent on a surface of the steel, high-temperature annealing, and finally, applying an insulating coating on the surface of the steel and performing hot stretching, temper rolling and annealing, thereby obtaining a finished product; carrying out, by means of pulse laser, scanning grooving on a single surface or both surfaces of the resultant silicon steel sheet after cold rolling, or after decarburizing annealing, or after high temperature annealing or after hot stretching, temper rolling and annealing, and forming grooves parallel with each other in a rolling direction of the silicon steel sheet; wherein a single pulse time width of the pulse laser is 100 ns or less, and a peak energy density of a single pulse is 0.05 J/cm.sup.2 or more; the energy density of a single laser beam in a single scan E.sub.s, is 1 J/cm.sup.2 to 100 J/cm.sup.2; wherein beam spot(s) of the pulse laser is a single beam spot or a combination of a plurality of beams spots, the combination of the plurality of beams spots is composed of a plurality of beam spots linearly arranged along a scanning direction, a number of beam spots is 2˜300; wherein in the single beam spot or the combination of the plurality of beams spots, a shape of the beam spot(s) is circular or elliptic, and a diameter a of the beam spot(s) in the scanning direction is 5 μm to 1 mm, and a diameter b of the beam spot(s) in a direction perpendicular to the scanning direction is 5 μm to 300 μm wherein an average value of spacing d.sub.m between the beam spots of the combination of the plurality of beams spots in the scanning direction is between c/5 and 5c, where c is an average diameter of the beam espots in the scanning direction; said scanning grooving being carried out through multiple scannings for each groove produced in the scanning grooving, wherein a product of the number of beam spots of the pulse laser and a number of the scannings is 5 or more.

2. The method for manufacturing stress-relief-annealing-resistant, low-iron-loss grain-oriented silicon steel according to claim 1, wherein the scanning grooving is carried out after hot stretching, temper rolling and annealing; after the scanning grooving, the silicon steel sheet is coated with secondary insulating coating(s) on one or both surfaces thereof and is then sintered.

3. The method for manufacturing stress-relief-annealing-resistant, low-iron-loss grain-oriented silicon steel according to claim 1, wherein the wavelength of the pulse laser is 0.3 to 3 μm.

4. The method for manufacturing stress-relief-annealing-resistant, low-iron-loss grain-oriented silicon steel according to claim 1, wherein the grooves formed on the surface(s) of the silicon steel sheet have a depth of 5 to 35 μm and a width of 8 to 310 μm, and wherein deposits on both sides of the grooves have a height of 2.5 μm or less, and the angle between the grooves and the lateral direction of the silicon steel sheet is 45° or less.

5. The method for manufacturing stress-relief-annealing-resistant, low-iron-loss grain-oriented silicon steel according to claim 1, wherein when the single surface of the grain-oriented silicon steel sheet is grooved, the spacing between adjacent grooves in the rolling direction of the silicon steel sheet is 1 to 10 mm; when the both surfaces of the grain-oriented silicon steel sheet are grooved, the spacing between adjacent grooves in the rolling direction of the silicon steel sheet is 2 to 20 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of the single laser beam spot and the combination of a plurality of beams spots used in the present invention.

DETAILED DESCRIPTION

(2) The present invention will be further described below with reference to Examples and drawings.

Example 1

(3) The grain-oriented silicon steel was subjected to iron smelting, steel smelting and continuous casting to obtain a billet containing C: 0.07%, Si: 3.1%, Mn: 0.14%, Al: 0.020%, N: 0.01%, S: 0.01% in mass %. Then, the billet was subjected to hot rolling and single cold rolling to achieve a final thickness of 0.23 mm. After performing decarburization annealing to form a surface oxide layer, coating an annealing separation agent containing MgO as the main component on the surface, and high-temperature annealing at 1250° C. for 20 hours. After washing away the unreacted residual MgO, laser heat-resistant scoring was performed on a single surface of the steel plate. The parameters of laser scanning scoring were as follows: the laser pulse time width was 10 ns, the laser wavelength was 1066 nm, the repetition frequency was 800 KHz, the diameter b of the beam spot perpendicular to the scanning direction was 50 μm, the spacing d.sub.m between beam spots in a group of beam spots was 10 μm, and the number of beam spots was 5. The depth of the grooves formed by scoring was controlled to be 15-18 μm, and the width was controlled to be 50-55 μm. The angle between the groove and the lateral direction of the steel plate is 8°, and the spacing between adjacent grooves in the rolling direction is 4.5 mm. Table 1 shows the parameters of specific scoring process. After the scoring was completed, final annealing was performed to apply the tension coating.

(4) Epstein 0.5 kg method in GB/T3655-2008 was used for magnetic measurement of the silicon steel sheets. GB/T19289-2003 was used to determine the lamination coefficient of the silicon steel sheets. The measurement results of Examples 1-10 and Comparative Examples 1-3 are shown in Table 2.

(5) As can be seen from Tables 1 and 2, in Examples 1-10, as the peak energy density of a single pulse E.sub.p and the energy flux density of a single laser beam in a single scan E.sub.s are within the range defined by the present invention, the iron loss P17/50 of the silicon steel sheet after scoring is 0.75 W/kg or less, and the lamination coefficient remains 95% or more. In Comparative Examples 1 and 2, the energy flux density of a single laser beam in a single scan is outside the range of the present invention. Although the iron loss P17/50 is good in Comparative Examples 1 and 2, the lamination coefficient decreases significantly. In Comparative Example 3, the peak energy density of a single pulse is too low, which results in poor scoring effects (when the scan times reaches 30, the depth of the grooves formed by laser scoring is only 3.3 μm) and high iron loss, and thus it has no industrial value.

Example 2

(6) The grain-oriented silicon steel was subjected to iron smelting, steel smelting and continuous casting to obtain a billet containing C: 0.05%, Si: 3.7%, Mn: 0.10%, Al: 0.03%, N: 0.016%, S: 0.013% in mass %. Then, the billet was subjected to hot rolling and single cold rolling to achieve a final thickness of 0.26 mm. After performing decarburization annealing to form a surface oxide layer, coating an annealing separation agent containing MgO as the main component on the surface, and performing high-temperature annealing at 1250° C. for 20 hours. After washing away the unreacted residual MgO, hot stretching, temper rolling and annealing was performed to apply a tension coating. After that, laser scoring was performed on both the upper and lower surfaces of the steel plate. The laser wavelength is 533 nm and the repetition frequency is 600 KHz. The pulse width, laser output power, beam spot size, beam spot combination, scanning speed, scan times and other parameters were adjusted to achieve the desired scoring effect. Table 3 shows the parameters of specific scoring process. The grooves are perpendicular to the rolling direction of the steel plate. The spacing between adjacent grooves in the rolling direction is 6 mm. After completing the scoring, the insulating coating was applied again and dried and sintered to form the final grain-oriented silicon steel sheet.

(7) Epstein 0.5 kg method in GB/T3655-2008 was used for magnetic measurement of the silicon steel sheets. GB/T19289-2003 was used to determine the lamination coefficient of the silicon steel sheets. The measurement results of Examples 11-20 and Comparative Examples 4-12 are shown in Table 4.

(8) As can be seen from Tables 3 and 4, in Examples 11-20, as the pulse width, beam spot size, parameters of the combination of beam spots, and the product of the number of beam spots and the scan times are all within the range of the present invention, the height of the protrusions on both sides of the groove formed by scoring is 2.5 μm or less, and the magnetic properties of the silicon steel sheet are good after stress-relief annealing. In Comparative Examples 4-12, as the above parameters are outside the range of the present invention, the height of the protrusions on both sides of the groove formed by the scoring is more than 2.5 μm, the magnetic induction or the lamination coefficient is significantly reduced.

Example 3

(9) The grain-oriented silicon steel was subjected to iron smelting, steel smelting and continuous casting to obtain a billet containing C: 0.09%, Si: 2.9%, Mn: 0.12%, Al: 0.019%, N: 0.016%, S: 0.012% in mass %. Then, the billet was subjected to hot rolling and single cold rolling to achieve a final thickness of 0.22 mm. After performing decarburization annealing to form a surface oxide layer, linear microgrooves were scored on the surface of the steel plate using a pulse laser with a pulse time width of 0.5 nanoseconds. The output power of the laser was 100 W, the wavelength of the light wave was 533 nm, and the repetition frequency was 200 KHz. The beam spot focused on the surface of the steel plate was circular. The laser was a combination of multiple beam spots, and the number of beam spots was 20. The spacing between beam spots in the group of beam spots was 40 μm, and the laser scanning speed was 10 m/s. The scan times, scanning direction, and offset direction of scanning were adjusted to obtain different groove depth, width, and the angle between the score line and the lateral direction of the steel plate. Table 5 shows the parameters of specific scoring process.

(10) The above samples were subjected to a decarburization annealing process at a temperature of 830° C. to form a surface oxide layer. Then, MgO separation agent was applied to the surface of the steel plate. After the steel plate was made into steel coils, it was kept under high temperature annealing conditions at 1200° C. for 20 hours. Finally, after washing away the residual MgO, an insulating coating was applied on the surface of the steel coil, and the final hot stretching, temper rolling and annealing was performed to obtain a finished silicon steel sheet.

(11) Epstein 0.5 kg method in GB/T3655-2008 was used for magnetic measurement of the silicon steel sheets. GB/T19289-2003 was used to determine the lamination coefficient of the silicon steel sheets. The measurement results of Examples 21-30 and Comparative Examples 13-21 are shown in Table 6.

(12) As can be seen from Tables 5 and 6, in Examples 21-30, as the groove parameters and the score line of the laser scoring are within the scope of the present invention, both the iron loss P17/50 and the magnetic induction B8 are good. On the other hand, in Comparative Examples 13-21, as the groove parameters and the score line of the laser scoring are outside the range of the present invention, P17/50 is too high or B8 is obviously low.

(13) In summary, the present invention uses instantaneous high-energy laser to score the silicon steel surface. The method of the invention has the advantages of high processing efficiency and good scoring effect, and is particularly suitable for the manufacture of high-efficiency coiled iron core transformers, which can effectively save the power loss caused by transmission and distribution in the power grid and has good applicability.

(14) TABLE-US-00001 TABLE 1 Diameter b Energy of beam flux spot(s) in a density Height Diameter direction of a of a perpen- Peak single protru- of beam dicular energy laser Number sions spot(s) in to Scan density beam in of beam on both Laser scanning scanning speed of single a single spots × Groove Groove sides of power direction direction V.sub.c Scan pulse E.sub.p scan E.sub.s Scan depth width grooves (W) (μm) (μm) (cm/s) times (J/cm.sup.2) (J/cm.sup.2) times (μm) (μm) (μm) Example 1 10 500 50 1000 10 0.06 2.5 50 17.6 51.8 0 Example 2 20 200 50 1000 8 0.32 5.1 40 16.8 52.1 0 Example 3 100 100 50 1000 2 3.18 25.5 10 16.9 53.8 1.1 Example 4 100 50 50 1000 2 6.37 25.5 10 15.9 54.3 1 Example 5 390 50 50 1000 1 24.83 99.3 5 16.7 53.9 1.8 Example 6 20 200 50 1000 8 0.32 5.1 40 17.2 52.8 0 Example 7 100 100 50 1000 2 3.18 25.5 10 15.9 53.1 0 Example 8 100 50 50 1000 2 6.37 25.5 10 16.3 52.2 0.6 Example 9 390 50 50 1000 1 24.83 99.3 5 16.8 53.8 0.8 Example 10 40 50 50 10000 10 2.55 1.0 50 16.2 54.3 2.1 Comparative 40 50 50 11000 15 2.55 0.9 75 15.9 57.9 2.7 Example 1 Comparative 400 50 50 1000 1 25.46 101.9 5 17.3 59.2 2.6 Example 2 Comparative 7 500 50 1000 30 0.04 1.8 150 3.3 50.6 0 Example 3

(15) TABLE-US-00002 TABLE 2 Magnetic properties of silicon steel sheets after stress-relief annealing P17/50 (W/kg) B8 (T) Lamination coefficient (%) Example 1 0.735 1.912 97.3 Example 2 0.748 1.909 97.5 Example 3 0.736 1.907 96.5 Example 4 0.742 1.91 96.2 Example 5 0.729 1.908 95.9 Example 6 0.75 1.914 96.8 Example 7 0.741 1.909 97.6 Example 8 0.733 1.909 97.2 Example 9 0.746 1.911 96.9 Example 10 0.748 1.908 95.4 Comparative Example 1 0.763 1.901 93.8 Comparative Example 2 0.742 1.905 94.2 Comparative Example 3 0.886 1.92 97.5

(16) TABLE-US-00003 TABLE 3 Energy Beam spot size flux Diameter density b in a Parameters of Peak of a Height direction the combination energy single of perpen- of beam spots density laser protru- Diameter dicular Spacing of beam Number sions a in to between single in a of beam on both Pulse Laser scanning scanning Number beam Scan pulse single spots × Groove Groove sides of Width power direction direction of beam spots speed Scan E.sub.p scan E.sub.s Scan depth width grooves (ns) (W) (μm) (μm) spots (μm) (cm/s) times (J/cm.sup.2) (J/cm.sup.2) times (μm) (μm) (μm) Example 11 40 100 15 15 5 20 1000 4 94.3 84.9 20 20.5 26.6 0.5 Example 12 40 100 15 15 5 20 1000 1 94.3 84.9 5 19.5 22.7 1.5 Example 13 40 100 15 15 5 3 1000 2 94.3 84.9 10 19.7 22.6 1.6 Example 14 40 100 15 15 1 1000 8 94.3 84.9 8 19.6 29.9 0.9 Example 15 40 100 15 80 300 80 1000 1 17.7 84.9 300 21.5 23.6 1.2 Example 16 0.5 100 100 5 5 100 1000 2 42.4 12.7 10 20.5 106.5 2.1 Example 17 0.5 2000 100 1000 5 100 10000 2 4.2 25.5 10 21.3 106.7 0.9 Example 18 0.5 100 5 50 100 35 5000 2 84.9 50.9 200 21.7 33.4 1.5 Example 19 0.5 1000 300 300 2 100 1000 10 2.4 42.4 20 19.8 307.3 1.8 Example 20 100 100 15 15 2 20 1000 4 94.3 84.9 8 21.3 26.4 1 Comparative 40 100 15 15 1 1000 4 94.3 84.9 4 19.8 30.1 3 Example 4 Comparative 40 100 15 15 4 2.5 1000 5 94.3 84.9 20 20.9 33.2 2.9 Example 5 Comparative 40 100 15 15 4 76 1000 5 94.3 84.9 20 19.5 26.6 2.5 Example 6 Comparative 40 100 15 80 301 80 1000 1 17.7 84.9 301 19.5 29.3 3.6 Example 7 Comparative 0.5 100 100 4.5 3 20 1000 10 47.2 12.7 30 19.8 106.6 2.8 Example 8 Comparative 0.5 2000 100 1010 3 100 10000 10 4.2 25.5 30 21.8 106.1 2.7 Example 9 Comparative 0.5 100 4.5 50 3 35 10000 10 94.3 28.3 30 21.6 22.6 3.1 Example 10 Comparative 0.5 1000 301 400 50 35 10000 2 1.8 4.2 100 21.9 306.4 3.1 Example 11 Comparative 102 100 15 15 2 20 1000 4 94.3 84.9 8 20.2 28.3 3.2 Example 12

(17) TABLE-US-00004 TABLE 4 Magnetic properties of silicon steel sheets after stress-relief annealing P17/50 (W/kg) B8 (T) Lamination coefficient (%) Example 11 0.853 1.912 97.5 Example 12 0.867 1.909 97.0 Example 13 0.887 1.911 96.9 Example 14 0.870 1.908 96.8 Example 15 0.866 1.909 96.5 Example 16 0.846 1.905 96.5 Example 17 0.850 1.905 96.8 Example 18 0.868 1.903 96.2 Example 19 0.849 1.912 96.6 Example 20 0.857 1.909 97.1 Comparative Example 4 0.866 1.901 95.4 Comparative Example 5 0.868 1.903 95.6 Comparative Example 6 0.872 1.907 95.8 Comparative Example 7 0.874 1.911 94.3 Comparative Example 8 0.864 1.903 93.9 Comparative Example 9 0.879 1.905 95.0 Comparative Example 10 0.857 1.908 94.9 Comparative Example 11 0.833 1.897 95.6 Comparative Example 12 0.883 1.91 94.6

(18) TABLE-US-00005 TABLE 5 Energy Beam spot size flux Angle Diameter density between b in a Peak of a Spacing the Height direction energy single between grooves of perpen- density laser adjacent and protru- Diameter dicular of beam Number grooves lateral sions a in to single in a of beam in direction on both Laser scanning scanning pulse single spots × Groove Groove rolling of steel sides of power Scored direction direction Scan Ep scan Es Scan depth width direction plate groove (W) surface (μm) (μm) times (J/cm.sup.2) (J/cm.sup.2) times (μm) (μm) (μm) (°) (μm) Example 21 100 Single 40 40 8 39.8 31.8 160 22.3 45.6 5 6 0.5 Example 22 10 Single 5 8 2 159.2 25.5 40 5 12 5 6 0 Example 23 100 Single 40 40 15 39.8 31.8 300 35 46.3 5 6 0.6 Example 24 10 Single 5 8 4 159.2 25.5 80 6 8 5 6 0 Example 25 100 Single 40 40 18 39.8 31.8 360 23.1 310 5 6 0.2 Example 26 100 Single 40 40 8 39.8 31.8 160 22.8 46.2 1 6 0.2 Example 27 100 Single 40 40 8 39.8 31.8 160 21.9 44.7 10 6 0.7 Example 28 100 Single 40 40 8 39.8 31.8 160 22 43.9 4.5 45 0.3 Example 29 100 Both 40 40 6 39.8 31.8 120 17.6 42.8 2 6 0.8 Example 30 100 Both 40 40 6 39.8 31.8 120 16.9 43.3 20 6 0.2 Comparative 10 Single 4.5 8 2 176.8 28.3 40 4.8 12.4 5 6 0 Example 13 Comparative 100 Single 36 40 16 44.2 35.4 320 35.5 42.2 5 6 0.5 Example 14 Comparative 10 Single 5 8 2 159.2 25.5 40 6.3 7.8 5 6 0 Example 15 Comparative 100 Single 40 40 18 39.8 31.8 360 21.6 312 5 6 0.3 Example 16 Comparative 100 Single 40 40 8 39.8 31.8 160 20.9 44.8 0.9 6 0.3 Example 17 Comparative 100 Single 40 40 8 39.8 31.8 160 22.8 43.3 10.2 6 0.4 Example 18 Comparative 100 Single 40 40 8 39.8 31.8 160 23.3 42.1 4.5 46 0.6 Example 19 Comparative 100 Both 40 40 6 39.8 31.8 120 17.3 43.3 1.9 6 0.4 Example 20 Comparative 100 Both 40 40 6 39.8 31.8 120 18.2 42.9 20.5 6 0.4 Example 21

(19) TABLE-US-00006 TABLE 6 Magnetic properties of silicon steel sheets after stress-relief annealing P17/50 (W/kg) B8 (T) Lamination coefficient (%) Example 21 0.756 1.916 97.5 Example 22 0.785 1.923 97.6 Example 23 0.753 1.902 96.6 Example 24 0.782 1.920 97.3 Example 25 0.756 1.901 96.6 Example 26 0.756 1.900 96.4 Example 27 0.778 1.918 97.1 Example 28 0.759 1.909 97.7 Example 29 0.748 1.900 96.5 Example 30 0.788 1.921 97.1 Comparative Example 13 0.802 1.918 96.9 Comparative Example 14 0.751 1.894 96.4 Comparative Example 15 0.811 1.923 96.9 Comparative Example 16 0.772 1.894 96.4 Comparative Example 17 0.746 1.894 96.5 Comparative Example 18 0.809 1.917 97.1 Comparative Example 19 0.805 1.903 96.9 Comparative Example 20 0.748 1.890 97.0 Comparative Example 21 0.825 1.923 97.0