Preparation method of non-oriented silicon steel, non-oriented silicon steel and application

Abstract

The invention belongs to the technical field of non-oriented silicon steel production, and particularly relates to a preparation method of non-oriented silicon steel, the non-oriented silicon steel and application. Comprising the following steps: heating a continuous casting plate blank, and carrying out hot continuous rolling on the heated hot plate blank to obtain a hot rolled plate; the hot-rolled plate is subjected to primary cold rolling to obtain a cold-rolled plate, then the cold-rolled plate is subjected to primary annealing to obtain an annealed cold-rolled plate, the reduction rate of primary cold rolling is 70-75%, and the relation between the temperature and time of primary annealing meets the condition that t time is equal to 300-0.3 T temperature; carrying out secondary cold rolling on the annealed cold-rolled sheet to obtain strip steel, and carrying out secondary annealing on the strip steel; the continuous casting slab comprises the following chemical components in percentage by weight: less than or equal to 0.0020% of C, 3.0-4.0% of Si, 0.30-0.60% of Mn, 0.5-1.0% of Als, less than or equal to 0.05% of P, less than or equal to 0.0015% of S, less than or equal to 0.0015% of N, less than or equal to 0.0020% of Ti and the balance of Fe and inevitable impurities. The high-grade non-oriented silicon steel prepared by the method disclosed by the invention has excellent magnetic performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-oriented silicon steel production, and specifically relates to a preparation method of non-oriented silicon steel, non-oriented silicon steel and applications, and in particular to a preparation method of high-grade non-oriented silicon steel that does not require normalization, high-grade non-oriented silicon steel and applications. Background Art

[0002] High silicon content non-oriented silicon steel has become an important material in the field of "high, precise and sharp" iron core manufacturing in the electromagnetic conversion process due to its thin thickness and low iron loss, and is widely used in super-large generators, ultra-efficient home appliances, new energy vehicles and other fields. The normalization process can promote the recrystallization of the deformed hot-rolled plate and the growth of grains, so it is one of the important processes in silicon steel production. At present, domestic high-grade non-oriented silicon steel generally adopts the production method of one cold rolling after normalization. For 0.20-0.25mm thin-gauge high-grade silicon steel, the production method of normalization, one cold rolling, intermediate annealing, secondary cold rolling and final annealing is adopted. However, normalization treatment will inevitably increase the silicon steel production process, thus affecting the production efficiency of non-oriented silicon steel and increasing production energy consumption, especially high Si and thin-gauge non-oriented silicon steel, which generally requires two cold rolling and intermediate annealing, and the process is longer. With the proposal of "low carbon" and "green production", in order to reduce carbon emissions and reduce production processes, the non-normalization treatment of high Si grade silicon steel has become an important development direction for silicon steel production enterprises in the next step.

[0003] The prior art "A high magnetic induction non-oriented silicon steel without normalization and a method for producing thin slabs" discloses that the invention is optimized through the composition and process design, that is, through the composite addition of Sn and Sb, the reduction of the heating temperature of the ingot, the optimal selection of the coiling temperature, and the strict control of the cooling rate of the coil at ≤20℃ / h, the improvement of the texture by adding Sn and Sb segregation elements, and the control of the hot rolling coiling temperature to improve the hot rolling structure and improve the magnetic properties of the finished product. It involves low-grade silicon steel with Si content in the range of 0.1-1.0%, iron loss P 1.5 / 5 Above 3.5W / kg; the prior art "A method for producing high-grade non-oriented silicon steel without normalization" discloses that the invention realizes high-grade non-oriented silicon steel products without normalization by controlling the hot rolling thickness, the first cold rolling thickness, and the second cold rolling thickness. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that when non-oriented silicon steel is prepared by non-normalization in the prior art, the addition of precious metal elements easily increases the production cost, and the thickness of the intermediate product is constantly adjusted during the production process, resulting in a more complicated production process. Therefore, a preparation method of non-oriented silicon steel, non-oriented silicon steel and application are proposed. The preparation method of the present invention reasonably controls the chemical composition and content of the continuous casting slab, and optimizes the relevant parameters of the primary cold rolling and primary annealing processes. The method of the present invention can be used to prepare high-grade non-oriented silicon steel, and the iron loss P of the non-oriented silicon steel is 1.5 / 50 ≤2.00W / kg, P 1.0 / 400 ≤12.50W / kg, magnetic induction B 50 ≥1.67T, and the preparation method has simple process and low energy consumption.

[0005] The first aspect of the present invention provides a method for preparing non-oriented silicon steel, the method comprising the following steps:

[0006] Step S1, heating the continuous casting slab, and hot rolling the heated hot slab to obtain a hot rolled plate;

[0007] Step S2, cold rolling the hot rolled sheet to obtain a cold rolled sheet, and then annealing the cold rolled sheet to obtain an annealed cold rolled sheet, wherein the reduction ratio of the cold rolling is 70-75%, and the relationship between the temperature and time of the annealing satisfies t 时间 =300-0.3T 温度 ;

[0008] Step S3, performing secondary cold rolling on the annealed cold-rolled sheet to obtain a steel strip, and performing secondary annealing on the steel strip;

[0009] The chemical composition of the continuous casting slab includes, by weight percentage: C≤0.0020%, Si: 3.0-4.0%, Mn: 0.30-0.60%, Als: 0.5-1.0%, P: ≤0.05%, S≤0.0015%, N≤0.0015%, Ti≤0.0020%, and the rest is Fe and unavoidable impurities.

[0010] Preferably, the conditions for the primary annealing include: a temperature of 900 to 950° C. and a time of 20 to 30 seconds.

[0011] Preferably, the chemical composition of the continuous casting slab, measured by weight percentage, includes: C: 0.0013-0.0020%, Si: 3.30-3.50%, Mn: 0.30-0.50%, Als: 0.55-0.7%, P: 0.015-0.035%, S: 0.0008-0.0012%, N: 0.0011-0.0013%, Ti: 0.0007-0.0015%, and the rest is Fe and unavoidable impurities.

[0012] Preferably, the specific method of performing secondary annealing on the steel strip is: performing secondary annealing on the steel strip in an annealing furnace containing a nitrogen-hydrogen mixed atmosphere at 950-1000°C, with a holding time of 35-45s, a dew point temperature of ≤-10°C, and a unit tension of ≤2.5N / mm in the annealing furnace. 2 .

[0013] Preferably, in step S1, the hot rolling includes rough rolling and finish rolling, the rough rolling has 3 to 5 passes, the rough rolling outlet temperature is ≥1000°C, the finish rolling temperature is 840 to 900°C, and the coiling temperature is 550 to 690°C.

[0014] Preferably, the reduction ratio of the primary cold rolling is 1 to 2 times the reduction ratio of the secondary cold rolling.

[0015] Preferably, in step S1, the conditions for heating the continuous casting slab include: a heating temperature of 1090-1200° C. and a heating time of 180-230 min.

[0016] Preferably, the thickness of the hot-rolled plate is 150-250 mm, the thickness of the cold-rolled plate is 0.5-0.7 mm, and the thickness of the strip steel is 0.2-0.3 mm.

[0017] The second aspect of the present invention provides a non-oriented silicon steel prepared by the preparation method described above.

[0018] The third aspect of the present invention proposes an application of the above-mentioned non-oriented silicon steel as a core material in electromagnetic conversion.

[0019] The preparation method of non-oriented silicon steel, the non-oriented silicon steel and the application of the present invention have the following beneficial effects:

[0020] In the present invention, without adding precious metal elements Sb and Sn, and without going through a normalization process, by rationally regulating the chemical composition and content of the continuous casting slab, and optimizing the relevant process parameters of the primary cold rolling and primary annealing processes, a high-grade non-oriented silicon steel with a Si content of 3.0-4.0% and an Al content of 0.50-1.0% is prepared, and the iron loss P of the non-oriented silicon steel is 1.5 / 50≤2.00W / kg, P 1.0 / 400 ≤12.50W / kg, magnetic induction B 50 ≥1.67T, and the preparation method has simple process and low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The metallographic structure diagram of the hot-rolled plate prepared in Implementation 2 of the present invention;

[0022] Figure 2 The metallographic structure diagram of the annealed cold-rolled sheet prepared in Implementation 2 of the present invention;

[0023] Figure 3 This is the metallographic structure diagram of the normalized plate after heat treatment prepared in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0024] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0025] The first aspect of the present invention provides a method for preparing non-oriented silicon steel, the method comprising the following steps:

[0026] Step S1, heating the continuous casting slab, and hot rolling the heated hot slab to obtain a hot rolled plate;

[0027] Step S2, cold rolling the hot rolled sheet to obtain a cold rolled sheet, and then annealing the cold rolled sheet to obtain an annealed cold rolled sheet, wherein the reduction ratio of the cold rolling is 70-75%, and the relationship between the temperature and time of the annealing satisfies t 时间 =300-0.3T 温度 ;

[0028] Step S3, performing secondary cold rolling on the annealed cold-rolled sheet to obtain a steel strip, and performing secondary annealing on the steel strip;

[0029] The chemical composition of the continuous casting slab includes, by weight percentage: C≤0.0020%, Si: 3.0-4.0%, Mn: 0.30-0.60%, Als: 0.5-1.0%, P: ≤0.05%, S≤0.0015%, N≤0.0015%, Ti≤0.0020%, and the rest is Fe and unavoidable impurities.

[0030] In a specific embodiment of the preparation method of the present invention, raw materials with C≤0.0020%, Si: 3.0-4.0%, Mn: 0.30-0.60%, Als: 0.5-1.0%, P: ≤0.05%, S≤0.0015%, N≤0.0015%, Ti≤0.0020%, and the rest being Fe and inevitable impurities are subjected to molten iron pretreatment, converter steelmaking, vacuum treatment, and then continuously cast into 150-250mm thick continuous casting slabs.

[0031] In the present invention, Si is an element that increases resistance and is the most important alloying element for electrical steel. To obtain low iron loss, the Si content needs to be increased. However, the increase in Si increases the brittleness of the material, which will reduce the rollability during the cold rolling process, and is prone to the risk of strip breakage and edge cracking, affecting the overall production process. Therefore, the Si content is controlled to be 3.0-4.0%; Mn and S form MnS, which can prevent the hot brittleness caused by the formation of low-melting FeS along the grain boundary. Therefore, a certain amount of manganese must be ensured to improve the hot rolling plasticity. When the Mn content is less than 0.30%, it will be unfavorable for hot rolling operation. When the Mn content is greater than 0.60%, the formation of MnS will increase, and it will become an inclusion in the strip later, affecting the performance; Als has a similar effect to Si, increasing the ρ value, reducing the γ zone and promoting grain growth, which can reduce iron loss, and the effect on the strength and hardness of the strip is not as obvious as that of silicon. When the Als content is less than 0.5%, it will affect the electromagnetic properties, and when the Als content is greater than 1.0%, it will be unfavorable for the production process. N and Al are easy to form small AlN particles, which will pin the grain boundaries and affect the growth of grains in the annealing process. In addition to combining with Mn to form MnS, S will also form small Cu2S precipitation phase with a small amount of Cu. The size of Cu2S is generally small, between 30 and 200nm. Cu2S will pin the grain boundaries and affect the growth of grains in the annealing process. Ti will form small-sized TiN, TiC and Ti(CN) with C and N, and the size of N, S is less than 100nm. , Ti elements are impurity elements. The fine precipitates formed will pin the grain boundaries and affect the grain growth during the subsequent annealing process. Therefore, it is generally required that the lower the content of such elements, the better; C is a harmful element in non-oriented silicon steel. When the C content is greater than 0.0020%, it will react with Ti to form TiC, affecting the grain growth during the subsequent annealing process. P is a grain boundary segregation element. When the P content is greater than 0.05%, under low carbon conditions, the amount of segregation along the grain boundaries will increase, embrittlement will occur, and the processing performance will be affected.

[0032] In a preferred embodiment of the preparation method of the present invention, the chemical composition of the continuous casting slab, measured by weight percentage, includes: C: 0.0013% to 0.0020%, for example, 0.0013%, 0.0018% or 0.0020%; Si: 3.30% to 3.50%, for example, 3.30%, 3.45% or 3.50%; Mn: 0.30% to 0.50%, for example, 0.30%, 0.45% or 0.50%; Als: 0.55% to 0.7%, for example, 0.55%, 0.60% or 0.70%; 0%; P: 0.015-0.035%, for example, 0.015%, 0.025% or 0.035%; S: 0.0008-0.0012%, for example, 0.0008%, 0.0009% or 0.0012%; N: 0.0011-0.0013%, for example, 0.0011%, 0.0012% or 0.0013%; Ti: 0.0007-0.0015%, for example, 0.0007%, 0.0012% or 0.0015%; the rest is Fe and unavoidable impurities.

[0033] In a specific embodiment of the preparation method of the present invention, in step S1, the continuous casting slab is heated and hot rolled by hot charging, and the heating temperature of the casting is controlled below 1200°C. A lower heating temperature is beneficial to the reduction of iron loss and the dissolution of precipitates, but it will increase the difficulty of hot rolling control. Therefore, it is generally above 1090°C. The heating time is generally controlled to be more than 120 minutes, but in order to control the precipitation of fine inclusions, the heating time should not be too long. Therefore, the conditions for heating the continuous casting slab include: a heating temperature of 1090-1200°C, and a heating time of 180-230 minutes.

[0034] In a specific embodiment of the preparation method of the present invention, in step S1, the hot rolling includes rough rolling and finish rolling, the rough rolling has 3 to 5 passes, the rough rolling outlet temperature is ≥1000°C, and an intermediate billet with a thickness of 35 to 45 mm is obtained, and then the intermediate billet is finish rolled to 1.8 to 2.3 mm by a 7-stand finishing mill, the final rolling temperature is 840 to 900°C, and the coiling temperature is 550 to 690°C to obtain a hot-rolled plate.

[0035] In a specific embodiment of the preparation method of the present invention, in step S2, the hot-rolled plate is subjected to a single cold rolling to obtain a cold-rolled plate, the thickness of the cold-rolled plate is 0.5-0.7 mm, for example, it can be 0.5 mm, 0.6 mm or 0.7 mm; the reduction rate of the single cold rolling is 70-75%, for example, it can be 70%, 71.43%, 72.22%, 72.73% or 75%, when the reduction rate of the single cold rolling is less than 70% or greater than 75%, it will affect the formation of favorable texture.

[0036] In the specific embodiment of the preparation method of the present invention, as the primary annealing time and temperature increase, the iron loss tends to decrease (becomes better), and the magnetic induction also tends to decrease (becomes worse). In order to obtain a better balance point, the relationship between the primary annealing temperature and time satisfies t 时间 =300-0.3T 温度 In a preferred embodiment, the conditions of the primary annealing include: a temperature of 900-950° C., such as 900° C., 930° C. or 950° C.; and a time of 20-30 s, such as 20 s, 21 s or 30 s.

[0037] In a specific embodiment of the preparation method of the present invention, in step S3, the annealed cold-rolled sheet is subjected to secondary cold rolling to obtain a steel strip, the thickness of the steel strip is 0.2-0.3 mm, and the reduction rate of the primary cold rolling is 1-2 times the reduction rate of the secondary cold rolling.

[0038] In a specific implementation of the preparation method of the present invention, in step S3, the secondary annealing temperature is higher than the primary annealing temperature. Under the same conditions, the annealing time increases, and the iron loss and magnetic induction both tend to decrease. The higher the primary annealing temperature, the greater the influence of the annealing time on the magnetic properties. Therefore, the specific method of performing secondary annealing on the strip is: the strip is subjected to secondary annealing in an annealing furnace containing a nitrogen-hydrogen mixed atmosphere (the volume ratio of N2 to H2 is 7:3) at 950-1000°C, the holding time is 35-45s, the dew point temperature is ≤-10°C, so as to obtain the required recrystallized structure, and the unit tension in the annealing furnace is ≤2.5N / mm 2 .

[0039] In a specific embodiment of the preparation method of the present invention, in step S3, the method further includes: coating an insulating coating on the surface of the strip after secondary annealing, drying and curing at a temperature below 500°C to obtain excellent insulation properties, and finally preparing non-oriented silicon steel.

[0040] The second aspect of the present invention provides a non-oriented silicon steel prepared by the preparation method described above, wherein the Si content of the non-oriented silicon steel is between 3.0% and 4.0%, the Al content is between 0.50% and 1.0%, and the iron loss P of the non-oriented silicon steel is 1.5 / 50 ≤2.00W / kg, P 1.0 / 400 ≤12.50W / kg, magnetic induction B 50 ≥1.67T.

[0041] The third aspect of the present invention proposes an application of the above-mentioned non-oriented silicon steel as a core material in electromagnetic conversion.

[0042] The experimental methods or test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0043] Example 1

[0044] A method for preparing non-oriented silicon steel, the method comprising the following steps:

[0045] Step S1, pre-treating the raw materials with the chemical composition shown in Table 1 with molten iron, smelting steel in a converter, and continuously casting into a 230 mm thick continuous casting slab after vacuum treatment, heating the continuous casting slab at 1080° C. for 200 min by hot charging to obtain a hot slab, and rough rolling the heated hot slab for 5 passes, and then fine rolling the slab to 2.2 mm through 7 stands, the intermediate slab thickness is 43 mm, the rough rolling outlet temperature is 1020° C., the final rolling temperature is 860° C., and the coiling temperature is 650° C. to obtain a hot rolled plate;

[0046] Step S2: the obtained hot-rolled sheet is not subjected to normalization treatment, but directly subjected to one-time cold rolling to an intermediate thickness of 0.60 mm, with a reduction rate controlled at 72.73%, to obtain a cold-rolled sheet, and then the cold-rolled sheet is subjected to one-time annealing to obtain an annealed cold-rolled sheet, with an annealing temperature of 950° C. and an annealing time of 15 s;

[0047] Step S3, secondary cold rolling the annealed cold-rolled sheet to a finished product thickness of 0.30 mm to obtain a steel strip, and secondary annealing the steel strip in a nitrogen-hydrogen mixed atmosphere (N2:H2=7:3) at 980°C, with the holding time controlled at 42s, the dew point below -10°C, and the unit tension in the furnace during the annealing process being 2.5N / mm 2 Then, an insulating coating is applied on the surface of the strip, and the strip is dried and solidified at a temperature of 500°C to obtain non-oriented silicon steel A1.

[0048] Example 2

[0049] A method for preparing non-oriented silicon steel, the method comprising the following steps:

[0050] Step S1, pre-treating the raw materials with the chemical composition shown in Table 1 with molten iron, smelting in a converter, and continuously casting into a 230 mm thick continuous casting slab after vacuum treatment, heating the continuous casting slab at 1120° C. for 180 min by hot charging to obtain a hot slab, and rough rolling the heated hot slab for 5 passes, and then fine rolling the slab to 2.1 mm on 7 stands, the intermediate slab thickness is 42 mm, the rough rolling outlet temperature is 1010° C., the final rolling temperature is 840° C., and the coiling temperature is 650° C. to obtain a hot rolled plate, and the structure of the hot rolled plate is as shown in Figure 1 As shown;

[0051] Step S2: The obtained hot-rolled sheet is not subjected to normalization treatment, but directly subjected to one-time cold rolling to an intermediate thickness of 0.60 mm, with a reduction ratio of 71.43% to obtain a cold-rolled sheet, and then the cold-rolled sheet is subjected to one-time annealing to obtain an annealed cold-rolled sheet, with an annealing temperature of 930° C. and an annealing time of 21 s. The structure of the annealed cold-rolled sheet is as follows: Figure 2 As shown, from Figure 2 It can be seen that the grains of the annealed cold-rolled sheet are relatively uniform, with an average grain size of 42 μm;

[0052] Step S3, secondary cold rolling the annealed cold-rolled sheet to a finished product thickness of 0.25 mm to obtain a steel strip, and secondary annealing the steel strip in a nitrogen-hydrogen mixed atmosphere (N2:H2=7:3) at 990°C, with the holding time controlled at 38s, the dew point below -10°C, and the unit tension in the furnace during the annealing process being 2.0N / mm 2 Then, an insulating coating is applied on the surface of the strip, and it is dried and solidified at a temperature of 500°C to obtain non-oriented silicon steel A2.

[0053] Example 3

[0054] A method for preparing non-oriented silicon steel, the method comprising the following steps:

[0055] Step S1, pre-treating the raw materials with the chemical composition shown in Table 1 with molten iron, smelting in a converter, and continuously casting into a 200 mm thick continuous casting slab after vacuum treatment, heating the continuous casting slab at 1115° C. for 170 min by hot charging to obtain a hot slab, and rough rolling the heated hot slab for 3 passes, and then fine rolling the slab to 1.8 mm through 7 stands, the intermediate slab thickness is 35 mm, the rough rolling outlet temperature is 1040° C., the final rolling temperature is 840° C., and the coiling temperature is 650° C. to obtain a hot rolled plate;

[0056] Step S2: the obtained hot-rolled sheet is not subjected to normalization treatment, but directly subjected to one-time cold rolling to an intermediate thickness of 0.50 mm, with a reduction ratio controlled at 72.22% to obtain a cold-rolled sheet, and then the cold-rolled sheet is subjected to one-time annealing to obtain an annealed cold-rolled sheet, with an annealing temperature of 900° C. and an annealing time of 30 s;

[0057] Step S3, secondary cold rolling the annealed cold-rolled sheet to a finished product thickness of 0.20 mm to obtain a steel strip, and secondary annealing the steel strip in a nitrogen-hydrogen mixed atmosphere (N2:H2=7:3) at 970°C, with the holding time controlled at 35s, the dew point below -10°C, and the unit tension in the furnace during the annealing process being 2.5N / mm 2 Then, an insulating coating is applied on the surface of the strip, and it is dried and cured at a temperature of 500°C to obtain non-oriented silicon steel A3.

[0058] Comparative Example 1

[0059] The chemical composition of the raw materials is shown in Table 1. The method of Example 1 is followed, except that in step S2, the temperature and time of the primary annealing do not satisfy the relationship t 时间 =300-0.3T 温度 The process parameters are shown in Table 2, and non-oriented silicon steel B1 is obtained.

[0060] Comparative Example 2

[0061] The chemical composition of the raw materials is shown in Table 1. The method of Example 2 is implemented, except that in step S2, the reduction rate of the primary cold rolling is not in the range of 70-75%. The process parameters are shown in Table 2, and non-oriented silicon steel B2 is obtained.

[0062] Comparative Example 3

[0063] The chemical composition of the raw materials is shown in Table 1. The remaining production methods are normalized by heat treatment (temperature 870 ° C, time 4 min), and the organization is as shown in Figure 3 As shown, the uniformity of the organization is relatively poor, the surface layer is fine recrystallized grains, while the grain size of the middle layer is larger. After one cold rolling to a thickness of 0.25 mm, the secondary annealing process is the same as in Example 2, and the process parameters are shown in Table 2 to obtain non-oriented silicon steel B3.

[0064] Comparative Example 4

[0065] The chemical composition of the raw materials is shown in Table 1, and the process parameters are shown in Table 2, and non-oriented silicon steel B4 is obtained.

[0066] Comparative Example 5

[0067] The chemical composition of the raw materials is shown in Table 1, and the process parameters are shown in Table 2, and non-oriented silicon steel B5 is obtained.

[0068] Table 1 Chemical composition of raw materials of Examples 1 to 3 and Comparative Examples 1 to 5

[0069] C Si Mn P S Als N Ti Example 1 0.0020 3.30 0.30 0.025 0.0012 0.70 0.0011 0.0012 Example 2 0.0013 3.45 0.50 0.015 0.0009 0.60 0.0012 0.0015 Example 3 0.0018 3.50 0.45 0.035 0.0008 0.55 0.0013 0.0007 Comparative Example 1 0.0020 3.30 0.30 0.025 0.0012 0.70 0.0011 0.0012 Comparative Example 2 0.0013 3.45 0.50 0.015 0.0009 0.60 0.0012 0.0015 Comparative Example 3 0.0013 3.45 0.50 0.015 0.0009 0.60 0.0012 0.0015 Comparative Example 4 0.0026 4.00 0.50 0.060 0.0009 0.20 0.0022 0.0025 Comparative Example 5 0.0019 2.90 0.30 0.008 0.0009 0.70 0.0018 0.0028

[0070] Table 2 Process parameters of Examples 1 to 3 and Comparative Examples 1 to 5

[0071]

[0072]

[0073] Test Case

[0074] The magnetic properties of the non-oriented silicon steel products A1~A3 and B1~B5 were tested using the GB / T 3655-2000 method. The test results are shown in Table 3.

[0075] Table 3 Magnetic properties test results of A1~A3 and B1~B5

[0076]

[0077] According to the results in Table 3, by reasonably adjusting the chemical composition and content of the continuous casting slab and controlling the reduction rate of the primary cold rolling to 70-75%, the relationship between the temperature and time of the primary annealing satisfies t 时间 =300-0.3T 温度 The method of the present invention is used to prepare a high-grade non-oriented silicon steel with a Si content of 3.0-4.0% and an Al content of 0.50-1.0%, and the iron loss P of the non-oriented silicon steel is 1.5 / 50 ≤2.00W / kg, P 1.0 / 400 ≤12.50W / kg, magnetic induction B 50 ≥1.67T, the non-oriented silicon steel can be widely used in electromagnetic conversion, and the preparation method is simple and has low energy consumption.

[0078] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing non-oriented silicon steel, characterized in that: The preparation method comprises the following steps: Step S1, heating the continuous casting slab, and hot rolling the heated hot slab to obtain a hot rolled plate; Step S2, cold rolling the hot rolled sheet to obtain a cold rolled sheet, and then annealing the cold rolled sheet to obtain an annealed cold rolled sheet, wherein the reduction ratio of the cold rolling is 70-75%, and the relationship between the temperature and time of the annealing satisfies t 时间 =300-0.3T 温度 ; Step S3, performing secondary cold rolling on the annealed cold-rolled sheet to obtain a steel strip, and performing secondary annealing on the steel strip; The chemical composition of the continuous casting slab includes, by weight percentage: C≤0.0020%, Si: 3.0-4.0%, Mn: 0.30-0.60%, Als: 0.5-1.0%, P: ≤0.05%, S≤0.0015%, N≤0.0015%, Ti≤0.0020%, and the rest is Fe and unavoidable impurities.

2. The method for preparing non-oriented silicon steel according to claim 1, characterized in that: The conditions of the primary annealing include: a temperature of 900 to 950° C. and a time of 20 to 30 seconds.

3. The method for preparing non-oriented silicon steel according to claim 1, characterized in that: The chemical composition of the continuous casting slab, measured by weight percentage, includes: C: 0.0013-0.0020%, Si: 3.30-3.50%, Mn: 0.30-0.50%, Als: 0.55-0.7%, P: 0.015-0.035%, S: 0.0008-0.0012%, N: 0.0011-0.0013%, Ti: 0.0007-0.0015%, and the rest is Fe and unavoidable impurities.

4. The method for preparing non-oriented silicon steel according to claim 1, characterized in that: The specific method of performing secondary annealing on the steel strip is as follows: performing secondary annealing on the steel strip in an annealing furnace containing a nitrogen-hydrogen mixed atmosphere at 950-1000°C, with a holding time of 35-45s, a dew point temperature of ≤-10°C, and a unit tension of ≤2.5N / mm in the annealing furnace. 2 .

5. The method for preparing non-oriented silicon steel according to claim 1, characterized in that: In step S1, the hot rolling includes rough rolling and finish rolling, the rough rolling has 3 to 5 passes, the rough rolling outlet temperature is ≥1000°C, the finish rolling temperature is 840 to 900°C, and the coiling temperature is 550 to 690°C.

6. The method for preparing non-oriented silicon steel according to claim 1, characterized in that: The reduction ratio of the first cold rolling is 1 to 2 times the reduction ratio of the second cold rolling.

7. The method for preparing non-oriented silicon steel according to claim 1, characterized in that: In step S1, the conditions for heating the continuous casting slab include: a heating temperature of 1090-1200° C. and a heating time of 180-230 min.

8. The method for preparing non-oriented silicon steel according to claim 1, characterized in that: The thickness of the hot-rolled plate is 150-250 mm, the thickness of the cold-rolled plate is 0.5-0.7 mm, and the thickness of the strip steel is 0.2-0.3 mm.

9. Non-oriented silicon steel prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the non-oriented silicon steel according to claim 9 as a core material in electromagnetic conversion.

Images