CN111778452A - Non-oriented electrical steel plate with excellent magnetic property and smelting method thereof - Google Patents
Non-oriented electrical steel plate with excellent magnetic property and smelting method thereof Download PDFInfo
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- 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
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- 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 by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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- 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 by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- 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 by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- 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
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- 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
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- 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
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
Abstract
The invention discloses a non-oriented electrical steel plate with excellent magnetic property and a smelting method thereof, wherein the chemical components of the non-oriented electrical steel plate with excellent magnetic property are controlled in the following ranges in percentage by mass: c: 0-0.004%, Si: 0.2-2.0%, Mn: 0.2-1.0%, S: 0.005-0.025%, Al: 0.2-1.2%, N: 0-0.005%, O: 0-0.005%, Cu: 0.005-0.02%, Ca: 0.0003 to 0.0035 percent, wherein the total content of Si and Al is 0.5 to 2.6 percent, and the balance is Fe and inevitable impurities. The smelting method comprises the following steps: the first step is that the blast furnace molten iron and the molten iron are pretreated, smelted in a converter, RH refined and continuously cast; step two, hot rolling processing, rough rolling, finish rolling and coiling; step three, hot rolling, acid washing, continuous rolling, coiling, cold rolling, front cleaning, continuous annealing, rear cleaning and insulating coating. The invention can shorten the RH refining treatment time, realize the continuous casting and casting process of continuous, smooth and stable production, and has simple and easy control of steel making and stable calcium yield.
Description
Technical Field
The invention relates to a non-oriented electrical steel plate with excellent magnetic property and a smelting method thereof.
Background
For medium and small television and EI iron cores, from the viewpoint of improving efficiency and reducing cost, the non-oriented electrical steel plate is expected to obtain more competitive high magnetic induction and low iron loss on the premise of ensuring price advantage, the electromagnetic performance of the general non-oriented electrical steel plate is superior and inferior, mainly depends on the chemical composition design of steel, favorable control of texture and proper grain size of finished steel plates, on the premise of definite chemical composition design, hot rolling process system and continuous annealing process system, the control effect of the inclusions in the steel becomes the key for restricting the electromagnetic performance of the finished strip steel, in order to obtain a good effect of controlling inclusions in steel, different technologists combine the smelting process of steel, and develop a great deal of effective technical research on the aspects of genetic change, removal method, improvement effect and the like of inclusions.
In the invention patent with the application number of 201310261807.6 and the name of 'a high-magnetic-induction low-iron-loss non-oriented electrical steel plate and a manufacturing method thereof', the invention has strict control requirements on a deoxidation alloying process of RH refining, has complex calculation formula and complicated operation process, and needs to continuously carry out 1-2 or more than 3 cycles after the deoxidation alloying of RH refining in order to achieve good deoxidation effect, which puts forward special requirements on the control of RH refining treatment period, molten steel temperature and the like, more importantly, the subsequent hot rolling, cold rolling and heat treatment links have special and complex control requirements, the production process is complex, the process window is narrow, and the controllability is poor; the invention patent with application number 201210060172.9 entitled "non-oriented electrical steel sheet with excellent magnetism and calcium treatment method thereof", calcium treatment is carried out on the molten steel by adding calcium-iron alloy in the RH refining deoxidation alloying link, compared with the traditional calcium treatment by wire feeding treatment, the method has great technical progress and process adaptability, but because the molten steel is not specially treated in advance, the calcium treatment is carried out under the vacuum condition and needs to be carried out by adding in multiple batches, and the ratio of the interval time of Ca and Al to the total time after Al is added has strict requirements, therefore, the whole calcium treatment production process is relatively complex, the RH refining treatment period is long, the yield of calcium is very low, therefore, the manufacturing cost of the calcium treatment method is high, a large amount of generated impurities are difficult to effectively remove, and finally, the problems of large ladle or tundish nozzle blockage and the like are easily caused during continuous casting; the invention patent with application number 201210060172.9, entitled "non-oriented electrical steel plate with excellent magnetism and calcium processing method thereof", obtains proper TiC, TiN fixing effect by adding Ti into steel and rare earth processing, but because Ti is easily oxidized and nitrided, the Ti content in molten steel is only ppm level after RH refining decarburization, therefore, expensive Ti-iron alloy needs to be added again after RH refining deoxidation alloying, and the Ti content control stability in molten steel is poor due to slag-steel interface reaction at this time, the addition amount of REM, Ti-iron alloy is difficult to be determined conveniently and rapidly to meet the special requirements of the above invention formula; in addition, since the density of rare earth oxysulfide is between that of steel and slag, the rare earth oxysulfide is difficult to effectively float and remove in the continuous casting process, the continuous casting is also difficult to perform, and surface quality defects are generated in the subsequent production process.
Disclosure of Invention
The invention aims to provide a non-oriented electrical steel plate with excellent magnetic property and a smelting method thereof, which can shorten RH refining processing time, quickly remove large-particle inclusions in steel, effectively inhibit the generation of fine inclusions in steel, realize continuous, smooth and stable production of continuous casting and casting process, have simple and easy control of steel making in the calcium processing process, have very stable calcium yield, effectively reduce the number of harmful inclusions in steel and have large integral size of finished products.
In order to achieve the purpose, the invention adopts the following technical scheme:
a non-oriented electrical steel sheet having excellent magnetic properties, wherein the chemical composition of the non-oriented electrical steel sheet having excellent magnetic properties is controlled in the following ranges by mass percent: c: 0-0.004%, Si: 0.2-2.0%, Mn: 0.2-1.0%, S: 0.005-0.025%, Al: 0.2-1.2%, N: 0-0.005%, O: 0-0.005%, Cu: 0.005-0.02%, Ca: 0.0003 to 0.0035 percent, wherein the total content of Si and Al is 0.5 to 2.6 percent, and the balance is Fe and inevitable impurities.
Further, the preferable mass percentage of Ca is controlled within a range of 0.0005 to 0.0025%.
Further, the preferable control range of the mass percent of Cu is 0.008-0.02%.
Further, the preferable mass percentage of S is controlled within the range of 0.01-0.025%.
The invention also provides a smelting method of the non-oriented electrical steel plate with excellent magnetic property, which comprises the following steps:
the method comprises the following steps: the non-oriented electrical steel plate with the chemical components is subjected to blast furnace molten iron and molten iron pretreatment, converter smelting, RH refining and continuous casting in sequence to obtain a continuous casting billet;
step two: the continuous casting billet is sequentially subjected to hot rolling processing, rough rolling, finish rolling and coiling to obtain a hot rolled coil;
step three: the hot rolled coil is sequentially subjected to hot coiling, acid pickling, continuous rolling, coiling, cold coiling, pre-cleaning, continuous annealing, post-cleaning and insulating coating, and finally the non-oriented electrical steel plate with excellent magnetic property is obtained.
Further, after the smelting of the converter is finished, high-purity lime is continuously added into the steel ladle top slag, and the adding amount is 0.85kg/t steel-2.40 kg/t steel.
Further, the Ca alloy adding method is adopted for calcium treatment, and the effective adding amount of the Ca alloy is set as MCaAddition amount M of Ca alloyCa＝k*Free[0]-0.5, wherein k is 0.34-0.93.
Further, after RH refining is finished, the calculation formula of the quaternary alkalinity of the ladle top slag is as follows: r4＝(CaO+MgO)/(SiO2+Al2O3)，R4The content is 0.55 to 0.90.
Further, the improvement index of the oxide-based inclusion of Ca element is defined as: and I is Ca/(O +1/2S), wherein I is more than or equal to 0.11 and less than or equal to 0.71.
The invention has the following beneficial effects:
1. the invention adjusts the quality percentage control requirement of S as impurity element from lower to better to the components of Si, Mn, Al, Ca, Cu and the like designed according to the self, limits the quality percentage to 0.005-0.025 percent, preferably controls the range of the quality percentage to 0.01-0.025 percent, aims to effectively avoid the problems of overlong processing time, serious damage of refractory material, pollution of molten steel, great increase of desulphurization cost and the like caused by executing deep desulphurization operation in the smelting process, and instead promotes the rapid precipitation of MnS inclusion in the continuous casting or casting blank hot rolling process by increasing the content of the S element in steel, lays the foundation for the later period, ensures the full precipitation of MnS inclusion, needs to dynamically adjust the content of the Ca element according to the content of the S element in steel in the actual production so as to ensure that the S element can form the MnS inclusion with relatively large size as much as possible, rather than producing Cu of finer size with the decrease in continuous casting and billet hot rolling temperaturesxS inclusion, in order to control the proper quantity, size and form of MnS inclusion, the improvement index I of oxide inclusion in steel needs to be limited, I is required to be more than or equal to 0.11 and less than or equal to 0.71, wherein, when I is less than 0.11, Ca is insufficient for the modification of oxide, and the precipitation of MnS inclusion and the inhibition of Cu inclusion can not be effectively promotedxS inclusionPrecipitation of material, whereas an I above 0.71 indicates that excessive calcium treatment has occurred, wherein excess Ca will combine sufficiently with S to produce a large number of irregularly shaped CaS inclusions, rather than larger sized, ribbon-like or spheroidal MnS inclusions.
2. The invention adopts the Ca treatment by adding the Ca alloy while deoxidizing and alloying under the premise of uninterrupted RH refining production, thereby effectively avoiding the traditional wire feeding calcium treatment after RH refining is finished, effectively shortening the RH refining treatment time, effectively avoiding the problems of molten steel suction, oxidation, slag entrapment and the like caused by violent turnover of molten steel, and simultaneously, because Ca element is very active and the vapor pressure is lower, under the condition of RH refining vacuum treatment, in order to obtain higher Ca element content, a proper calcium treatment method is necessary, namely, the effective adding quantity M of the Ca alloyCaDepending on the free oxygen content at the end of the RH refining decarburization, the amount M of Ca alloy added isCa＝k×Free[O]-0.5, where k is 0.34-0.93, while at the same time avoiding as much as possible fine Cu inclusions on the premise of obtaining reasonable size and number of MnS inclusionsxThe invention combines thermodynamic calculation and production practice to verify that Cu with the content of 0.005-0.02 percent is added into steel under the premise of the design of a chemical composition system, so that the Cu is effectively promoted to be precipitated and grown under the condition of ensuring that MnS inclusions are fully precipitated and grownxEarly precipitation of S inclusions, Cu thus precipitatedxThe amount of S inclusions is small, the size is large, and the S inclusions are mainly in an ellipsoidal shape with the ratio of the major axis to the minor axis not more than 4, so that the electromagnetic performance of the finished steel sheet is not adversely affected, and the preferable content control requirement of Cu is 0.008-0.02% in order to reduce the ratio of the major axis to the minor axis of the ellipsoidal shape as much as possible, and in addition, the calcium content in the molten steel is lost when passing through a slag layer due to the strong oxidizing property and poor fluidity of the slag, so that the quaternary basicity R of the ladle top slag is limited after the RH refining treatment is finished4Quaternary basicity of ladle top slag R4The melting point of the slag is lower and the slag is acidic, so that the slag has good fluidity and spreadability and can be applied to the molten steel surfaceThe covering is uniform, and the oxidability is weak, so that the Ca in the molten steel can be effectively prevented from being oxidized by the slag and the escape of free Ca can be reduced. Because a large amount of SiO is generated during the deoxidation of RH refining2、Al2O3When SiO2、Al2O3After entering the slag, the quaternary alkalinity R of the ladle top slag4Will rapidly decrease, and therefore in order to ensure that a suitable quaternary basicity R of the ladle top slag is obtained4Continuously adding high-purity lime into the steel ladle top slag at the end of converter blowing and in the steel tapping process, wherein the adding amount of the high-purity lime is 0.85kg/t to 2.40kg/t steel, and no excessive CaS inclusion or small-size Cu is generated in a continuous casting billet obtained after smeltingxS inclusions appear, while only MnS inclusions of moderate number, uniform size, relatively regular shape are present.
3. After conventional hot rolling, cold rolling and continuous annealing, the finished steel plate can obtain good inclusion control effect, in the continuous annealing process, the grain size is easy to grow, the texture is easy to form, intermediate normalizing heat treatment is not needed, intermediate bell-type furnace annealing heat treatment is also not needed, the non-oriented electrical steel plate with excellent magnetic property can be obtained, and the iron loss P is15/50Not more than 3.8W/kg, magnetic induction B50Not less than 1.74T.
Drawings
Fig. 1 is a table diagram of chemical composition control performance of experimental examples and comparative examples in examples of the present invention.
Fig. 2 is a chart of process design and electromagnetic performance control performance of experimental examples and comparative examples according to an embodiment of the present invention.
Detailed Description
The technical solution in the embodiments of the present invention will be described below with reference to the accompanying drawings.
A non-oriented electrical steel sheet with excellent magnetic properties, characterized in that the chemical composition of the non-oriented electrical steel sheet with excellent magnetic properties is controlled in the following ranges by mass percent: c: 0-0.004%, Si: 0.2-2.0%, Mn: 0.2-1.0%, S: 0.005-0.025%, Al: 0.2-1.2%, N: 0-0.005%, O: 0-0.005%, Cu: 0.005-0.02%, Ca: 0.0003 to 0.0035 percent, wherein the total content of Si and Al is 0.5 to 2.6 percent, and the balance is Fe and inevitable impurities.
The preferable control range of the Ca mass percentage is 0.0005 to 0.0025%.
The preferable control range of the mass percent of Cu is 0.008-0.02%.
The preferable control range of the mass percentage of S is 0.01-0.025%.
The above chemical composition design control requirements are explained in detail below, specifically as follows:
the mass percent of C is 0-0.004%, the C can strongly inhibit the grain growth of finished steel, and can be easily combined with Nb, V, Ti and other magazine elements to generate fine harmful precipitates, so that the iron loss is increased and the magnetic aging is generated, and therefore, the C must be strictly controlled below 0.004%.
The mass percent of Si is 0.2-2.0%, the Si element can improve the resistivity of a matrix and effectively reduce the iron loss of steel, the manufacturing cost of steel can be increased and the magnetic induction of steel can be obviously reduced when the mass percent of Si is higher than 2.0%, and good deoxidation effect and iron loss reduction effect cannot be achieved when the mass percent of Si is lower than 0.2%.
The mass percent of Mn is 0.2-1.0%, the binding capacity of Mn and S elements is greater than that of Fe and S, which is beneficial to inhibiting the hot brittleness phenomenon of steel, so that Mn with the mass percent of more than 0.2% is necessary to be added, and when the mass percent of MnSi is higher than 1.0%, the beneficial recrystallization texture is deteriorated, and the magnetic induction of the steel is reduced.
The mass percent of P is 0-0.2%, and when the mass percent of P is higher than 0.2%, the cold brittleness phenomenon of steel is easily caused, and the cold rolling manufacturability is further reduced.
The mass percent of S is 0.005-0.025%, when the mass percent of S is less than 0.005%, the desulfurization production cost of each link of steel making can be greatly increased, and when the mass percent of S is more than 0.025%, harmful inclusions such as Mn, Cu, Ca and the like of S can be greatly increased, the growth of crystal grains is strongly hindered, and the magnetism of steel is deteriorated.
The mass percent of Al is 0.2-1.2%, and the effect of the Al element is similar to that of the Si element. When the mass percentage of Al is more than 1.2%, the magnetic induction of the steel is remarkably deteriorated, and when the mass percentage of Al is less than 0.2%, the good deoxidation effect and the iron loss reduction effect are not achieved.
When the mass percent of N is 0-0.005% and the mass percent of N is higher than 0.005%, harmful precipitates such as Nb, V, Ti and the like of N are greatly increased, crystal grain growth is hindered, and the magnetism of the steel is deteriorated.
When the mass percent of O is 0-0.005% and the mass percent of O is higher than 0.005%, harmful impurities such as Al, Si, Ca and the like of O are greatly increased, the growth of crystal grains is inhibited, and the magnetism of the steel is deteriorated.
The mass percent of Cu is 0.005-0.02%, when the mass percent of Cu is less than 0.005%, the precipitation time of S compounds can be greatly delayed, so that the sizes of precipitates are smaller, the danger of inhibiting the growth of crystal grains is larger, and when the mass percent of Cu is more than 0.02%, harmful inclusions such as Mn, Cu and the like of S are greatly increased, the growth of the crystal grains is strongly hindered, and the magnetism of steel is deteriorated.
When the mass percentage of Ca is 0.0003-0.0035%, the good effect of controlling oxide inclusions cannot be achieved when the mass percentage of Ca is less than 0.0003%, and when the mass percentage of Ca is more than 0.0035%, the production cost is greatly increased, the growth of crystal grains is inhibited, and the magnetism of steel is deteriorated.
The invention also provides a smelting method of the non-oriented electrical steel plate with excellent magnetic property, which comprises the following steps:
the method comprises the following steps: the non-oriented electrical steel plate with the chemical components is subjected to blast furnace molten iron and molten iron pretreatment, converter smelting, RH refining and continuous casting in sequence to obtain a continuous casting billet;
step two: the continuous casting billet is sequentially subjected to hot rolling processing, rough rolling, finish rolling and coiling to obtain a hot rolled coil;
step three: the hot rolled coil is sequentially subjected to hot coiling, acid pickling, continuous rolling, coiling, cold coiling, pre-cleaning, continuous annealing, post-cleaning and insulating coating, and finally the non-oriented electrical steel plate with excellent magnetic property is obtained.
Further, after the smelting of the converter is finished, high-purity lime is continuously added into the steel ladle top slag, and the adding amount is 0.85kg/t steel-2.40 kg/t steel.
Further, the Ca alloy adding method is adopted for calcium treatment, and the effective adding amount of the Ca alloy is set as MCaAddition amount M of Ca alloyCa＝k*Free[0]-0.5, wherein k is 0.34-0.93.
Further, after RH refining is finished, the calculation formula of the quaternary alkalinity of the ladle top slag is as follows: r4＝(CaO+MgO)/(SiO2+Al2O3)，R4The content is 0.55 to 0.90.
Further, the improvement index of the oxide-based inclusion of Ca element is defined as: and I is Ca/(O +1/2S), wherein I is more than or equal to 0.11 and less than or equal to 0.71.
The invention has the following beneficial effects:
1. the invention adjusts the quality percentage control requirement of S as impurity element from lower to better to the components of Si, Mn, Al, Ca, Cu and the like designed according to the self, limits the quality percentage to 0.005-0.025 percent, preferably controls the range of the quality percentage to 0.01-0.025 percent, aims to effectively avoid the problems of overlong processing time, serious damage of refractory material, pollution of molten steel, great increase of desulphurization cost and the like caused by executing deep desulphurization operation in the smelting process, and instead promotes the rapid precipitation of MnS inclusion in the continuous casting or casting blank hot rolling process by increasing the content of the S element in steel, lays the foundation for the later period, ensures the full precipitation of MnS inclusion, needs to dynamically adjust the content of the Ca element according to the content of the S element in steel in the actual production so as to ensure that the S element can form the MnS inclusion with relatively large size as much as possible, rather than producing Cu of finer size with the decrease in continuous casting and billet hot rolling temperaturesxS inclusion, in order to control the proper quantity, size and form of MnS inclusion, the improvement index I of oxide inclusion in steel needs to be limited, I is required to be more than or equal to 0.11 and less than or equal to 0.71, wherein, when I is less than 0.11, Ca is insufficient for the modification of oxide, and the precipitation of MnS inclusion and the inhibition of Cu inclusion can not be effectively promotedxOf S inclusionsPrecipitation, whereas an I above 0.71 indicates that the calcium treatment has been excessive, wherein the excess Ca will combine sufficiently with S to form a large number of irregularly shaped CaS inclusions, rather than large-sized, ribbon-like or spheroidal MnS inclusions.
2. The invention adopts the Ca treatment by adding the Ca alloy while deoxidizing and alloying under the premise of uninterrupted RH refining production, thereby effectively avoiding the traditional wire feeding calcium treatment after RH refining is finished, effectively shortening the RH refining treatment time, effectively avoiding the problems of molten steel suction, oxidation, slag entrapment and the like caused by violent turnover of molten steel, and simultaneously, because Ca element is very active and the vapor pressure is lower, under the condition of RH refining vacuum treatment, in order to obtain higher Ca element content, a proper calcium treatment method is necessary, namely, the effective adding quantity M of the Ca alloyCaDepending on the free oxygen content at the end of the RH refining decarburization, the amount M of Ca alloy added isCa＝k×Free[O]-0.5, where k is 0.34-0.93, while at the same time avoiding as much as possible fine Cu inclusions on the premise of obtaining reasonable size and number of MnS inclusionsxThe invention combines thermodynamic calculation and production practice to verify that Cu with the content of 0.005-0.02 percent is added into steel under the premise of the design of a chemical composition system, so that the Cu is effectively promoted to be precipitated and grown under the condition of ensuring that MnS inclusions are fully precipitated and grownxEarly precipitation of S inclusions, Cu thus precipitatedxThe amount of S inclusions is small, the size is large, and the S inclusions are mainly in an ellipsoidal shape with the ratio of the major axis to the minor axis not more than 4, so that the electromagnetic performance of the finished steel sheet is not adversely affected, and the preferable content control requirement of Cu is 0.008-0.02% in order to reduce the ratio of the major axis to the minor axis of the ellipsoidal shape as much as possible, and in addition, the calcium content in the molten steel is lost when passing through a slag layer due to the strong oxidizing property and poor fluidity of the slag, so that the quaternary basicity R of the ladle top slag is limited after the RH refining treatment is finished4Quaternary basicity of ladle top slag R4The melting point of the slag is lower and is acidic, so that the slag has good fluidity and spreadability, and the molten steel surface is coated with the slagThe cover is uniform, and the oxidability is weak, so that the Ca in the molten steel can be effectively prevented from being oxidized by the slag and the escape of free Ca can be reduced. Because a large amount of SiO is generated during the deoxidation of RH refining2、Al2O3When SiO2、Al2O3After entering the slag, the quaternary alkalinity R of the ladle top slag4Will rapidly decrease, and therefore in order to ensure that a suitable quaternary basicity R of the ladle top slag is obtained4Continuously adding high-purity lime into the steel ladle top slag at the end of converter blowing and in the steel tapping process, wherein the adding amount of the high-purity lime is 0.85kg/t to 2.40kg/t steel, and no excessive CaS inclusion or small-size Cu is generated in a continuous casting billet obtained after smeltingxS inclusions appear, while only MnS inclusions of moderate number, uniform size, relatively regular shape are present.
3. After conventional hot rolling, cold rolling and continuous annealing, the finished steel plate can obtain good inclusion control effect, in the continuous annealing process, the grain size is easy to grow, the texture is easy to form, intermediate normalizing heat treatment is not needed, intermediate bell-type furnace annealing heat treatment is also not needed, the non-oriented electrical steel plate with excellent magnetic property can be obtained, and the iron loss P is15/50Not more than 3.8W/kg, magnetic induction B50Not less than 1.74T.
Examples
The method comprises the steps of pretreating blast furnace molten iron, putting the blast furnace molten iron and a proper amount of outsourcing scrap steel into a 350t converter for smelting and purification, strictly controlling the temperature of the molten steel in the smelting process, smelting in the converter, and then respectively carrying out decarburization, deoxidation, alloying and calcium treatment in an RH refining process, wherein when the calcium treatment is carried out, a proper amount of calcium-containing alloy is required to be added according to the free oxygen of the molten steel when the RH refining decarburization is finished according to an empirical formula, on one hand, the calcium content in the molten steel is reasonably controlled, on the other hand, the oxidation inclusion index in the molten steel is controlled, the molten steel after the RH refining is finished is smoothly, efficiently and stably cast in a continuous casting manner to obtain a high-quality electrical steel plate with the thickness of 170-250 mm and the width of 800-1400 mm, and then carrying out hot rolling, acid pickling, cold rolling and continuous annealing on the continuous casting billet, and the electromagnetic performance of the finished strip steel is excellent, correspondingly, the experimental example which is produced according to the technical requirements of the production process and the comparative example which is produced according to the technical requirements of the original conventional production process are used for making the chemical component control actual performance tables of the experimental example and the comparative example, the chemical component control actual performance table is shown in figure 1, the process design and electromagnetic performance control actual performance tables of the experimental example and the comparative example are made, and the process design and electromagnetic performance control actual performance table is shown in figure 2.
In the experimental example, all chemical component control actual results and related process parameter control effects meet the design specification control requirements of the invention, so that the continuous casting process is smooth, efficient and stable, the electromagnetic performance of the finished strip steel is excellent, and the target design requirements can be well met. In contrast, in comparative example 13 of FIG. 1, the mass percentage of S in the steel was 0.0022% and was less than the lower limit of 0.0050% of the target design requirement, and the comparative heat was not calcium-treated to improve harmful inclusions in the steel, so the inclusion index I in the steel was only 0.10 and less than the lower limit of 0.11 of the target design requirement, and although the comparative heat was stable in casting without calcium treatment, the electromagnetic properties of the finished steel strip were poor and the iron loss P was poor15/50And magnetic induction B504.42W/kg and 1.738T respectively, which are both lower than the 3.8W/kg and 1.74T of the target design requirement, in a comparative example 14 of figure 1, the mass percent of S in the steel is 0.0036 percent, the content of Si and Al in the steel is 2.71 percent, the Free O content of the comparative heat is higher than 441ppm, the addition amount of lime of the slag on the top of the ladle is 1.15kg/T, and the alkalinity quaternization R of the slag is higher than that of the slag40.85, but the inclusion index I exceeds 0.71 and reaches 0.72, so that the magnetic induction B of the finished steel plate is achieved even if the addition amount of the effective calcium reaches 290.6kg50The serious deviation is 1.685T which is lower than 1.738T of the target design requirement, similarly, in the comparative example 15 and the comparative example 16 of the figure 2, the chemical composition control actual performance and each process parameter control effect which can not meet the design requirement of the invention exist, the corresponding continuous casting stability is poor, the normal and smooth casting can not be carried out, or the electromagnetic performance of the finished strip steel can not meet the target design requirement of the corresponding steel grade.
Claims (9)
1. A non-oriented electrical steel sheet with excellent magnetic properties, characterized in that the chemical composition of the non-oriented electrical steel sheet with excellent magnetic properties is controlled in the following ranges by mass percent: c: 0-0.004%, Si: 0.2-2.0%, Mn: 0.2-1.0%, S: 0.005-0.025%, Al: 0.2-1.2%, N: 0-0.005%, O: 0-0.005%, Cu: 0.005-0.02%, Ca: 0.0003 to 0.0035 percent, wherein the total content of Si and Al is 0.5 to 2.6 percent, and the balance is Fe and inevitable impurities.
2. The non-oriented electrical steel sheet having excellent magnetic properties as claimed in claim 1, wherein the preferable mass percentage of Ca is controlled in the range of 0.0005 to 0.0025%.
3. The non-oriented electrical steel sheet having excellent magnetic properties as claimed in claim 2, wherein the preferable mass percentage of Cu is controlled within a range of 0.008 to 0.02%.
4. The non-oriented electrical steel sheet having excellent magnetic properties as claimed in claim 3, wherein the preferable mass percentage of S is controlled in the range of 0.01 to 0.025%.
5. A method of producing a non-oriented electrical steel sheet excellent in magnetic properties according to any one of claims 1 to 4, characterized by comprising the steps of:
the method comprises the following steps: the non-oriented electrical steel plate with the chemical components is subjected to blast furnace molten iron and molten iron pretreatment, converter smelting, RH refining and continuous casting in sequence to obtain a continuous casting billet;
step two: the continuous casting billet is sequentially subjected to hot rolling processing, rough rolling, finish rolling and coiling to obtain a hot rolled coil;
step three: the hot rolled coil is sequentially subjected to hot coiling, acid pickling, continuous rolling, coiling, cold coiling, pre-cleaning, continuous annealing, post-cleaning and insulating coating, and finally the non-oriented electrical steel plate with excellent magnetic property is obtained.
6. The smelting method according to claim 5, wherein the high purity lime is continuously added to the ladle top slag after the converter smelting is completed, and the addition amount is 0.85kg/t steel to 2.40kg/t steel.
7. A smelting method according to claim 6, wherein the Ca alloy addition method is used for the calcium treatment, and the effective addition amount of the Ca alloy is set to MCaAddition amount M of Ca alloyCa＝k*Free[0]-0.5, wherein k is 0.34-0.93.
8. A smelting method according to claim 7, wherein after RH refining is completed, the formula for calculating the quaternary alkalinity of the ladle top slag is: r4＝(CaO+MgO)/(SiO2+Al2O3)，R4The content is 0.55 to 0.90.
9. The method according to claim 8, wherein the improvement index of the oxide-based inclusion of Ca element is defined as: and I is Ca/(O +1/2S), wherein I is more than or equal to 0.11 and less than or equal to 0.71.
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| CN114015931A (en) * | 2021-10-12 | 2022-02-08 | 邯郸钢铁集团有限责任公司 | Non-oriented electrical steel with excellent iron loss and magnetic property and production method thereof |
| CN114150211A (en) * | 2021-11-29 | 2022-03-08 | 中山市中圣金属板带科技有限公司 | Production method of steel plate for electromagnetic shielding and steel plate for electromagnetic shielding |
| CN115198203A (en) * | 2021-04-09 | 2022-10-18 | 宝山钢铁股份有限公司 | Non-oriented electrical steel plate free of normalizing intermediate annealing and manufacturing method thereof |
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