A low-noise non-oriented silicon steel and its production method and application

Abstract

The present invention provides a low-noise non-oriented silicon steel and its production method and application, the composition: C≤0.0025%, 2.15%≤Si≤2.90%, 0.25%≤Mn≤0.65%, P≤0.25%, 0.3%≤Als≤0.6%, S≤0.0030%, N≤0.0030%, Ti≤0.0030%, the rest is Fe and inevitable impurities. Compared with the prior art, the present invention adopts a reasonable alloy composition design to clearly obtain the most suitable composition system of non-oriented silicon steel with lower noise. The method requires that the purpose of controlling the surface tension of silicon steel is achieved by controlling the thickness of the insulating coating, thereby further controlling magnetostriction and reducing noise. The low-noise arc-extinguishing coil manufactured has a working noise of ≤55dB.

Description

Technical Field

[0001] The invention belongs to the technical field of non-oriented electrical steel production, and particularly relates to a high-grade low-noise non-oriented silicon steel for a low-noise arc-extinguishing coil, and a production method and application thereof. Background Art

[0002] Arc suppression coil is an inductor coil with an iron core. It is connected between the neutral point of the transformer (or generator) and the earth to form an arc suppression coil grounding system. The power system transmission line is grounded through the arc suppression coil, which is a small current grounding system. The noise of the arc suppression coil is a technical indicator that cannot be ignored. The national standard has made clear provisions on the noise standard of the arc suppression coil, which cannot be higher than 78 decibels. At present, some arc suppression coil manufacturers still use low-priced non-oriented silicon steel for manufacturing, and the noise cannot meet the national standard requirements.

[0003] The operating noise of arc extinguishing coil is mainly related to the magnetostriction of magnetic materials. In a periodically changing magnetic field, the silicon steel sheet of non-oriented silicon steel periodically changes its size, causing vibration of the air and generating noise. Magnetostriction is an inherent property of magnetic materials, so how to control and improve the noise of non-oriented silicon steel in the process of using arc extinguishing coil becomes a difficult problem.

[0004] The publication number CN105220071A published on January 6, 2016 disclosed "A Low-Noise Characteristic Oriented Silicon Steel and Its Manufacturing Method". This method controls the insulation coating tension between 6-8MPa, and the alloy composition satisfies: the content of Cu and S elements satisfies: 0.1%≤Cu≤0.5%, 0.01%≤S≤0.05%, and the atomic ratio Cu / S satisfies: 5≤Cu / S≤10. By controlling the alloy composition and film tension, the hysteresis expansion of the oriented silicon steel is reduced, thereby reducing the noise level during the operation of the transformer. This method describes a method for manufacturing low-noise oriented silicon steel, and does not mention the manufacture of non-oriented silicon steel.

[0005] Therefore, it is necessary to provide a low-noise non-oriented silicon steel. Summary of the invention

[0006] The purpose of the present invention is to provide a low-noise non-oriented silicon steel and a production method thereof, and to obtain a low-noise non-oriented silicon steel for arc extinguishing coils by adjusting alloy composition and matching annealing process and coating.

[0007] The low-noise non-oriented silicon steel provided by the present invention is used to manufacture low-noise arc-extinguishing coils. The manufactured low-noise arc-extinguishing coils have a working noise of ≤55dB.

[0008] The specific technical solutions of the present invention are as follows:

[0009] A low-noise non-oriented silicon steel comprising the following chemical components in mass percentage:

[0010] C≤0.0025%,

[0011] 2.15%≤Si≤2.90%,

[0012] 0.25%≤Mn≤0.65%,

[0013] P≤0.25%,

[0014] 0.3%≤Als≤0.6%,

[0015] S≤0.0030%,

[0016] N≤0.0030%,

[0017] Ti≤0.0030%,

[0018] The rest is Fe and inevitable impurities.

[0019] The chemical composition of the low-noise non-oriented silicon steel also satisfies: 3.2%≤Si+Mn+Als≤3.4%, 5≤Si / Als≤6, 4.5≤Si / Mn≤5.5; after a large number of composition design tests, the finished product whose composition meets this condition can meet the low noise requirement, and this composition system is conducive to maintaining the grain size between 65μm-80μm, making the grains more uniform, and helping to reduce magnetostriction.

[0020] The average grain size of the low-noise non-oriented silicon steel product meets the following requirements: 65 μm ≤ R avg ≤80μm;

[0021] The thickness of the low-noise non-oriented silicon steel product is 0.35 mm.

[0022] The present invention provides a method for producing low-noise non-oriented silicon steel, comprising the following steps:

[0023] 1) Hot metal pretreatment, converter steelmaking, vacuum treatment and then continuous casting;

[0024] 2) After cooling, the slab enters the heating furnace for heating;

[0025] 3) Hot rolling;

[0026] 4) Regular pickling line;

[0027] 5) Cold rolling on a reversible rolling mill;

[0028] 6) Finally, the finished product is annealed.

[0029] In step 1), continuously casting into a slab with a thickness of 200-300 mm;

[0030] In step 2), the slab is cooled and then heated in a heating furnace at a temperature not lower than 550°C;

[0031] In step 2), the heating furnace temperature is 1100-1250° C., and the heating and heat preservation time is ≥ 210 min;

[0032] In step 3), the hot rolling is performed at a final rolling temperature of 830-880°C to form a hot-rolled plate with a thickness of 2.2-2.6 mm, and the temperature is reduced to a coiling temperature of 630-670°C after air cooling and water cooling processes; the temperature of the hot-rolled strip is relatively high, and air cooling and water cooling are required to reduce the temperature to the target coiling temperature.

[0033] In step 4), the normalizing temperature is controlled at 850-930°C, the normalizing time is 2-5 minutes, and the pickling temperature is 75-80°C.

[0034] In step 5), after 6 rolling passes, the total cold rolling reduction rate is 84-86.5%, and the target thickness is 0.35 mm.

[0035] In step 6), the finished product is annealed by a rapid heating method in the heating section, the heating section temperature is 860-950°C, the time is 110-200s, the hydrogen volume fraction in the furnace is controlled at 5-10%; the dew point in the furnace is controlled at ≤-10°C;

[0036] In step 6), after annealing, the insulating coating is applied by a coating roller, and the insulating coating is cured at 440-570° C.; by adjusting the coating amount, the coating thickness of the finished product is ensured to be between 0.5 μm and 0.6 μm.

[0037] The arc extinguishing coil made of non-oriented silicon steel obtained by the above process has low noise. The most suitable gold component system for reducing magnetostriction of non-oriented silicon steel is obtained by adjusting the composition, and the coating thickness is controlled between 0.5μm-0.6μm. Too thick coating will affect the welding performance of the finished product; too low coating thickness cannot provide sufficient surface tension, which is not conducive to reducing magnetostriction.

[0038] The low-noise non-oriented silicon steel provided by the present invention is used to manufacture low-noise arc-extinguishing coils. The operating noise of the manufactured low-noise arc-extinguishing coils is ≤55dB.

[0039] Compared with the prior art, the present invention adopts a reasonable alloy composition design to clearly obtain the most suitable composition system of non-oriented silicon steel with less noise. The method requires controlling the thickness of the insulating coating to achieve the purpose of controlling the surface tension of the silicon steel, thereby further controlling magnetostriction and reducing noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The metallographic structure of the non-oriented silicon steel produced by the present invention is ferrite structure, and the grain size is about 73 μm. DETAILED DESCRIPTION

[0041] The present invention is described below in conjunction with embodiments.

[0042] Example 1

[0043] A method for producing low-noise non-oriented silicon steel comprises the following steps:

[0044] 1) After molten iron pretreatment, converter steelmaking, RH furnace refining and vacuum treatment, the molten steel is continuously cast into a slab with a thickness of 230 mm. The chemical composition weight percentages of the slab are: C 0.0025%, Si: 2.38%; Als: 0.42%; Mn: 0.49%; P: 0.0124%; S0.0018%, N0.0025%, Ti0.0018%, and the rest are Fe and unavoidable impurity elements.

[0045] 2) After the slab is cooled, it is heated in a heating furnace at a temperature not lower than 550°C. The temperature in the heating furnace is 1120°C and the heating and holding time is 230 minutes;

[0046] 3) After 7 hot rolling passes to a thickness of 2.3 mm, the final rolling temperature is 830°C, and after air cooling and water cooling, the coiling temperature is 660°C;

[0047] 4) The normalizing temperature is controlled at 930°C, the normalizing time is 2.5 min, and the pickling temperature is 75°C;

[0048] 5) Cold rolling on a reversible rolling mill, after 6 passes, the thickness is reduced to 0.35 mm;

[0049] 6) Finished product annealing: 950°C annealing, annealing time 110s, hydrogen gas volume fraction in the furnace 10%, furnace dew point controlled at ≤-10°C; after annealing, insulating coating is applied by coating roller, and the insulating coating is cured at 440-570°C. The finished product coating thickness is 0.5μm.

[0050] The average grain size R of the non-oriented silicon steel product manufactured by the above process is avg It is 73μm, and the arc extinguishing coil made of it has an operating noise of 50dB.

[0051] Example 2

[0052] A method for producing low-noise non-oriented silicon steel comprises the following steps:

[0053] 1) After molten iron pretreatment, converter steelmaking, RH furnace refining and vacuum treatment, the molten steel is continuously cast into a slab with a thickness of 230 mm. The chemical compositions of the slab are as follows by weight: C 0.0018%, Si: 2.43%, Als: 0.44%, Mn: 0.45%, P: 0.0078%, S 0.0015%, N0.0023%, Ti 0.0016%, and the rest are Fe and unavoidable impurity elements.

[0054] 2) After the slab is cooled, it is heated in a heating furnace at a temperature not lower than 550°C. The temperature of the slab in the heating furnace is 1120°C and the heating and holding time is 230 minutes;

[0055] 3) After 7 hot rolling passes, the steel is finished to a thickness of 2.3 mm, with a final rolling temperature of 845°C and a coiling temperature of 660°C;

[0056] 4) The normalizing temperature is controlled at 930°C, the normalizing time is 2.5 min, and the pickling temperature is 80°C;

[0057] 5) Cold rolling on a reversible rolling mill, after 6 passes, the thickness is reduced to 0.35 mm;

[0058] 5) Annealing at 950°C for 110s, with a hydrogen volume fraction of 10% and a dew point of ≤-10°C; after annealing, the insulating coating is applied by a coating roller, and the insulating coating is cured at 440-570°C, with a finished coating thickness of 0.52μm.

[0059] The average grain size R of the non-oriented silicon steel product manufactured by the above process is avg The diameter of the arc extinguishing coil is 75μm, and the arc extinguishing coil made of it has an operating noise of 53dB.

[0060] Comparative Example 1

[0061] A method for producing non-oriented silicon steel comprises the following steps:

[0062] 1) The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 230 mm, and the chemical composition of the slab is C 0.0015%; Si: 3.10%; Als: 1.09%; Mn: 0.30%; P: 0.008%; S: 0.005%, N: 0.005%, Ti: 0.005%, and the rest is Fe and unavoidable impurity elements.

[0063] 2) The temperature of the slab in the heating furnace is 1150°C, and the heating and holding time is 220 minutes;

[0064] 3) After 7 hot rolling passes, the steel is finished to a thickness of 2.3 mm, with a final rolling temperature of 840°C and a coiling temperature of 650°C;

[0065] 4) The normalizing temperature is controlled at 860°C, the normalizing time is 2.5 min, and the thickness is reduced to 0.35 mm after 6 passes of rolling;

[0066] 5) After annealing at 960°C for 260s, with a hydrogen volume fraction of 15% in the furnace, the insulating coating is applied by a coating roller, and the insulating coating is cured at 440-570°C. The finished coating thickness is 0.41 μm.

[0067] The arc extinguishing coil made from the non-oriented silicon steel product manufactured by the above process has a working noise of 80dB.

[0068] Comparative Example 2

[0069] A method for producing non-oriented silicon steel comprises the following steps:

[0070] 1) The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 230 mm. The chemical composition of the slab is C 0.0017%; Si: 2.65%; Als 0.74%; Mn: 0.20%; P: 0.010%; S: 0.005%, N: 0.005%, Ti: 0.005%, and the rest is Fe and unavoidable impurity elements.

[0071] 2) The temperature of the slab in the heating furnace is 1150°C, and the heating and holding time is 220 minutes;

[0072] 3) After 7 hot rolling passes, the steel is finished to a thickness of 2.3 mm, with a final rolling temperature of 880°C and a coiling temperature of 650°C;

[0073] 4) The normalizing temperature is controlled at 860°C, the normalizing time is 2.5 min, and the thickness is reduced to 0.35 mm after 6 passes of rolling;

[0074] 5) After annealing at 950°C for 260s, with a hydrogen volume fraction of 15% in the furnace, the insulating coating is applied by a coating roller, and the insulating coating is cured at 440-570°C. The finished coating thickness is 0.38μm.

[0075] The arc extinguishing coil made from the non-oriented silicon steel product manufactured by the above process has a working noise of 83dB.

[0076] Comparative Example 3

[0077] A method for producing non-oriented silicon steel comprises the following steps:

[0078] 1) The molten steel refined in the RH furnace is continuously cast into a slab with a thickness of 230 mm, and the chemical composition of the slab is C 0.0016%; Si: 2.80%; Als: 0.35%; Mn: 0.65%; P: 0.010%; S: 0.005%, N: 0.005%, Ti: 0.005%, and the rest is Fe and unavoidable impurity elements.

[0079] 2) The temperature of the slab in the heating furnace is 1150°C, and the heating and holding time is 220 minutes;

[0080] 3) After 7 hot rolling passes, the steel is finished to a thickness of 2.3 mm, the final rolling temperature is 880°C, and the coiling temperature is 650°C;

[0081] 4) The normalizing temperature is controlled at 860°C, the normalizing time is 2.5 min, and the thickness is reduced to 0.35 mm after 6 passes of rolling;

[0082] 5) After annealing at 950°C for 260s, with a hydrogen volume fraction of 15% in the furnace, the insulating coating is applied by a coating roller, and the insulating coating is cured at 440-570°C. The finished coating thickness is 0.38μm.

[0083] The arc extinguishing coil made from the non-oriented silicon steel product manufactured by the above process has a working noise of 84dB.

Claims

1. A low-noise non-oriented silicon steel, characterized in that: The low-noise non-oriented silicon steel comprises the following chemical components in mass percentage: C≤0.0025%， 2.15%≤Si≤2.90%, 0.25%≤Mn≤0.65%, P≤0.25%， 0.3%≤Als≤0.6%, S≤0.0030%， N≤0.0030%， Ti≤0.0030%, The rest is Fe and unavoidable impurities; The chemical composition of the low-noise non-oriented silicon steel also satisfies: 3.2%≤Si+Mn+Als≤3.4%, 5≤Si / Als≤6, 4.5≤Si / Mn≤5.5; The average grain size of the low-noise non-oriented silicon steel product meets the following requirements: 65 μm ≤ R avg ≤80μm; After annealing, the low-noise non-oriented silicon steel is coated with insulating coating by a coating roller, and the insulating coating is cured at 440-570° C. The thickness of the finished coating is between 0.5 μm and 0.6 μm.

2. A method for producing low-noise non-oriented silicon steel according to claim 1, characterized in that: The production method comprises the following steps: 1) Hot metal pretreatment, converter steelmaking, vacuum treatment and then continuous casting; 2) After cooling, the slab enters the heating furnace for heating; 3) Hot rolling; 4) Regular pickling line; 5) Cold rolling on a reversible rolling mill; 6) Finally, the finished product is annealed.

3. The production method according to claim 2, characterized in that: In step 2), the heating furnace temperature is 1100-1250° C., and the heating and heat preservation time is ≥210 min.

4. The production method according to claim 2, characterized in that: In step 3), the hot rolling has a final rolling temperature of 830-880°C and a coiling temperature of 630-670°C.

5. The production method according to claim 2, characterized in that: In step 4), the normalizing temperature is controlled at 850-930°C, the normalizing time is 2-5 minutes, and the pickling temperature is 75-80°C.

6. The production method according to claim 2, characterized in that: In step 6), the finished product is annealed at a temperature of 860-950°C in the heating section for 110-200s, and the hydrogen volume fraction in the furnace is controlled at 5-10%; the dew point in the furnace is controlled at ≤-10°C.

7. An application of the low-noise non-oriented silicon steel according to claim 1, characterized in that: Used to manufacture low-noise arc-extinguishing coils. The operating noise of the manufactured low-noise arc-extinguishing coils is ≤55dB.

Images