Non-normalized low-iron-loss high-magnetic-induction non-oriented silicon steel and manufacturing method thereof

Abstract

The silicon steel comprises the following components in percentage by weight: 0 to 0.005 percent of C, 1.3 to 2.8 percent of Si, 0.20 to 0.80 percent of Mn, 0 to 0.05 percent of P, 0.2 to 1.2 percent of Al, less than or equal to 0.005 percent of S, less than or equal to 0.005 percent of O, less than or equal to 0.005 percent of N, less than or equal to 0.003 percent of Nb, less than or equal to 0.003 percent of V, less than or equal to 0.003 percent of Ti, 0.001 to 0.005 percent of Ca, one or two of 0.02 to 0.15 percent of Sb, 0.02 to 0.15 percent of Sn and 0.1 to 0.4 percent of Cu, and the balance of Fe and inevitable impurities. By adding proper trace elements, adopting effective calcium treatment to control inclusions and matching with proper hot rolling, cold rolling and annealing processes, an unnormalized low-iron-loss high-magnetic-induction non-oriented silicon steel product is obtained. The minimum iron loss P15 / 50 of the manufactured non-oriented silicon steel product with the thickness of 0.5 mm is 2.73 w / kg, and the maximum magnetic induction intensity B50 / 50 can reach 1.735 T; the minimum iron loss P15 / 50 of the series with the thickness of 0.35 mm is 2.25 w / kg, and the maximum magnetic induction intensity B50 / 50 can reach 1.718 T.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to an amorphized low iron loss high magnetic induction non-oriented silicon steel and a manufacturing method thereof. Background Art

[0002] Silicon steel is mainly used in the manufacture of compressors and motor cores. With the implementation of the new energy efficiency standard for air conditioners, "Energy efficiency limit values ​​and energy efficiency grades for room air conditioners" and the new energy efficiency standard for motors, "Energy efficiency limit values ​​and energy efficiency grades for motors", people's increasing demand for high efficiency, energy saving and environmental protection has accelerated the technological revolution of upgrading non-oriented silicon steel products and promoted the widespread application of high-performance non-oriented electrical steel. More and more electrical equipment such as motors, compressors, and EI cores have put forward strict requirements on the iron loss and magnetic induction of non-oriented silicon steel. In order to improve the efficiency of compressors and motors, reduce the size, and reduce the weight, it is hoped that the iron loss of steel is as low as possible and the magnetic induction is as high as possible. Summary of the invention

[0003] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and to provide a normalized, low iron loss, high magnetic induction, non-oriented silicon steel and a method for manufacturing the same.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] The invention discloses a non-normalized, low iron loss, high magnetic induction, non-oriented silicon steel. The silicon steel is a silicon steel coil. The weight percentage of the silicon steel components is: C is 0-0.005%, Si is 1.3-2.8%, Mn is 0.20-0.80%, P is 0-0.05%, Al is 0.2-1.2%, S≤0.005%, O≤0.005%, N≤0.005%, Nb≤0.003%, V≤0.003%, Ti≤0.003%, Ca is 0.001-0.005%, and it also contains one or two of Sb is 0.02%-0.15%, Sn is 0.02%-0.15%, Cu is 0.1%-0.4%, and the rest is Fe and unavoidable impurities.

[0006] Furthermore, the silicon steel is a silicon steel coil with a thickness of 0.35 mm or 0.5 mm.

[0007] The invention also discloses a method for manufacturing the normalized low iron loss and high magnetic induction non-oriented silicon steel. The molten iron is subjected to KR pretreatment, and after converter steelmaking, one or two of trace elements Sb content of 0.02% to 0.15%, Sn content of 0.02% to 0.15%, and Cu content of 0.1% to 0.4% are added. The molten steel is subjected to refining, decarburization and deoxidation treatments, and then calcium treatment is performed to remove inclusions. After RH refining, the molten steel is continuously cast into a slab, which is coiled by high-temperature hot rolling. The hot coil is not subjected to a normalization process, and is cold-rolled into a cold coil after pickling once. The normalized low iron loss and high magnetic induction non-oriented silicon steel coil is obtained by annealing and coating in a protective atmosphere.

[0008] Furthermore, the Ca content after the calcium treatment is 0.001-0.005%.

[0009] Furthermore, the Ca content after the calcium treatment is 0.002-0.004%.

[0010] Furthermore, the high temperature hot rolling and coiling is specifically as follows: after heating the continuous casting slab to 1100-1180°C, rolling it into a hot coil according to a process of a final rolling temperature of 820-900°C and a coiling temperature of 560-650°C.

[0011] Furthermore, the annealing is specifically: high temperature, short time, rapid annealing, and the annealing temperature is in the range of 880-1000°C.

[0012] In the composition design of the present invention:

[0013] Si: 1.3-2.8%. Silicon can increase the resistivity of steel, promote grain coarsening, reduce grain boundaries, and thus reduce iron loss, but the magnetic induction intensity will also decrease. At the same time, under the condition of normalization process, considering the difficulty of cold rolling, it is necessary to control the upper limit of silicon content, which should not be too high. 2.8% is more appropriate as the upper limit.

[0014] Al: 0.20-1.2%. The role of aluminum is similar to that of silicon. Too low aluminum content will affect the deoxidation degree of steel, causing abnormal inclusions and deterioration of electromagnetic properties. Too high aluminum content will greatly reduce magnetic induction and increase the difficulty of cold rolling.

[0015] Mn: 0.20-0.8%. Manganese can improve hot-rolled plasticity and hot-rolled plate structure. With high manganese content, the MnS solid solution temperature increases, and the continuous annealing temperature can be appropriately increased to improve the electromagnetic properties of the finished strip.

[0016] Sb, Sn: Sb0.02%~0.15%, Sn0.02%~0.15%. Sb and Sn are grain boundary segregation elements. After adding Sb and Sn to non-oriented silicon steel, they will segregate on the surface of the steel to prevent nitriding, and can also segregate around the precipitates to hinder the solid solution of the precipitates, so that the precipitates remain in a coarse size state, thereby preventing the surface grain refinement and effectively reducing the iron loss value; Sb and Sn can also promote the formation of deformation bands within the grains, reduce the

[111] grains in the recrystallized structure, and thus increase the magnetic flux density of the steel. However, when the addition amount exceeds 0.15%, the steel becomes brittle, increasing the risk of defects such as plate and strip breakage and surface peeling during the manufacturing process.

[0017] Cu: 0.1% to 0.4%. Cu in non-oriented silicon steel mainly utilizes metal Cu to nucleate at crystal defects such as dislocations to produce Cu-rich phases to achieve precipitation strengthening. Cu-containing precipitated phases can reduce the structure and magnetic sensitivity of non-oriented silicon steel, and promote the formation of Goss texture by inhibiting {111} texture, thereby improving recrystallization texture and product magnetic properties. Increasing the Cu content in steel to combine it with S, so that copper sulfide is preferentially precipitated at a temperature higher than that of MnS precipitation, controlling the hot rolling and annealing temperatures to coarsen the precipitates, and making Cu form mainly cubic copper sulfide with good interface matching with steel, which can prevent the deterioration of iron loss. The surface segregation strength of Cu-containing non-oriented silicon steel increases with the increase of annealing temperature, but there are fewer grains in the direction of the easy magnetization axis and more grains in the direction of the difficult magnetization axis, which has a certain impact on magnetic sensitivity.

[0018] Ca: 0.001~0.005%. Calcium treatment can effectively remove small inclusions in steel. Production practice shows that when the residual Ca in steel is in the range of 0.001-0.005%, the calcium treatment is relatively complete, especially when the Ca content is in the range of 0.002-0.004%, liquid calcium aluminate can be formed, and inclusions can be effectively removed by floating, thus obtaining high-purity molten steel, reducing the iron loss value of the finished product and improving the magnetic induction strength. Calcium treatment is one of the effective methods to improve both iron loss and magnetic induction.

[0019] The beneficial effects of the present invention are as follows: the non-oriented silicon steel of the present invention, through reasonable design of main components such as Si and Al, adds appropriate trace elements, adopts effective calcium treatment to control inclusions, matches appropriate hot rolling, cold rolling and annealing processes, gives full play to the advantages of various components and process technologies without normalization process, and obtains non-normalized low iron loss and high magnetic induction non-oriented silicon steel products. The high-silicon and high-aluminum non-oriented silicon steel hot coil breaks the conventional process route, and can obtain good metallographic structure and favorable texture without normalization process, which is beneficial to the electromagnetic properties of the finished product. The iron loss P15 / 50 of the manufactured non-oriented silicon steel product 0.5mm thickness series is as low as 2.73w / kg, and the magnetic induction intensity B50 / 50 can reach up to 1.735T; the iron loss P15 / 50 of the 0.35mm thickness series is as low as 2.25w / kg, and the magnetic induction intensity B50 / 50 can reach up to 1.718T. It can be widely used in variable frequency air conditioner refrigerator compressors, as well as the manufacture of large, medium and small industrial motors. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with embodiments.

[0021] Embodiment 1:

[0022] The chemical composition of steel is shown in Table 1.

[0023] The molten iron is continuously cast into billets after KR pretreatment, converter steelmaking and RH refining. The continuously cast slabs are heated to 1120-1160°C, and conventionally hot rolled and coiled. The hot coils are pickled and then rolled into 0.5 mm thick hard rolled coils. The non-oriented silicon steel products are annealed in a protective atmosphere and coated. The electromagnetic properties are shown in Table 2.

[0024] Table 1: Chemical composition Unit: wt'%

[0025] Case Si Al Mn P C S O N Sn Sb Cu 1 1.33 0.81 0.20 0.02 0.0019 0.0018 0.0019 0.0014 / 0.07 / 2 1.37 0.78 0.22 0.02 0.0024 0.0017 0.0015 0.0015 / 0.03 / 3 1.50 0.60 0.41 0.02 0.0019 0.0017 0.0014 0.0012 0.15 / / 4 1.47 0.61 0.41 0.02 0.002 0.0018 0.0015 0.0014 0.08 / / 5 1.54 0.60 0.43 0.02 0.002 0.0019 0.0016 0.0015 0.03 / / 6 1.53 0.61 0.40 0.03 0.0016 0.0018 0.0018 0.0017 0.1 0.04 / 7 1.54 0.61 0.42 0.03 0.0020 0.002 0.0014 0.0014 0.06 0.10 / 8 1.52 0.62 0.40 0.02 0.0020 0.0019 0.0019 0.0018 / / 0.10 9 1.52 0.57 0.41 0.02 0.0018 0.0016 0.0020 0.0019 / / 0.30 10 2.23 0.27 0.21 0.02 0.0020 0.002 0.0020 0.0015 0.14 / / 11 2.21 0.27 0.21 0.02 0.0019 0.0023 0.0018 0.0017 0.06 / / 12 2.17 0.23 0.21 0.02 0.0018 0.0021 0.0019 0.0016 0.03 / /

[0026] Table 2: Hot rolling process and electromagnetic properties results

[0027]

[0028] Embodiment 2:

[0029] The chemical composition of steel is shown in Table 3.

[0030] The molten iron is continuously cast into billets after KR pretreatment, converter steelmaking and RH refining. The continuously cast slabs are heated to 1130-1170°C, and conventionally hot rolled and coiled. The hot coils are pickled and then rolled into 0.35 mm thick hard rolled coils. The non-oriented silicon steel products are obtained after annealing in a protective atmosphere and coating. The electromagnetic properties are shown in Table 4.

[0031] Table 3: Chemical composition Unit: wt'%

[0032] Example Si Al Mn P C S O N Sn Sb 1 1.52 0.64 0.80 0.02 0.0017 0.002 0.0015 0.0016 0.15 / 2 1.50 0.62 0.77 0.02 0.0018 0.0019 0.0018 0.0014 0.07 / 3 1.57 0.58 0.74 0.02 0.0024 0.0020 0.0016 0.0013 0.03 / 4 2.19 0.19 0.22 0.02 0.0019 0.0018 0.0014 0.0013 0.13 / 5 2.14 0.19 0.21 0.02 0.0018 0.0019 0.0015 0.0017 0.07 / 6 2.17 0.23 0.21 0.02 0.0019 0.0016 0.0016 0.0018 0.03 / 7 2.33 0.67 0.21 0.02 0.0020 0.002 0.0015 0.0016 0.14 / 8 2.35 0.64 0.25 0.02 0.0021 0.0017 0.0017 0.0015 0.04 0.02 9 2.35 0.67 0.27 0.02 0.0018 0.0014 0.0015 0.0014 0.06 / 10 2.83 1.16 0.36 0.02 0.0024 0.002 0.0016 0.0015 0.15 / 11 2.71 1.17 0.35 0.02 0.0025 0.0021 0.0017 0.0015 0.06 / 12 2.79 1.18 0.36 0.02 0.0022 0.0018 0.0015 0.0015 0.03 /

[0033] Table 4: Hot rolling process and electromagnetic properties results

[0034]

[0035] The above contents are only used to illustrate the technical solution of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention made by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A non-normalized low iron loss high magnetic induction non-oriented silicon steel, the silicon steel being a silicon steel coil, characterized in that: The silicon steel has the following components in weight percentage: C is 0-0.005%, Si is 1.3-2.8%, Mn is 0.20-0.80%, P is 0-0.05%, Al is 0.2-1.2%, S≤0.005%, O≤0.005%, N≤0.005%, Nb≤0.003%, V≤0.003%, Ti≤0.003%, Ca is 0.001-0.005%, and it also contains one or two of Sb (0.02%-0.15%), Sn (0.02%-0.15%), and Cu (0.1%-0.4%), and the rest is Fe and unavoidable impurities.

2. A non-normalized low iron loss high magnetic induction non-oriented silicon steel, characterized in that: The silicon steel is a silicon steel coil with a thickness of 0.35 mm or 0.5 mm.

3. The method for producing normalized low iron loss high magnetic induction non-oriented silicon steel according to claim 1 or 2, characterized in that: The molten iron is subjected to KR pretreatment, and after converter steelmaking, one or two of trace elements Sb content of 0.02% to 0.15%, Sn content of 0.02% to 0.15%, and Cu content of 0.1% to 0.4% are added. The molten steel is subjected to refining, decarburization and deoxidation treatments, and then calcium treatment is performed to remove inclusions. The molten steel is continuously cast into slabs after RH refining, and the slabs are coiled by high-temperature hot rolling. The hot coils are not subjected to a normalizing process, and are cold-rolled into cold coils after pickling once. The normalized low iron loss and high magnetic induction non-oriented silicon steel coils are obtained through annealing and coating in a protective atmosphere.

4. The method for producing normalized low iron loss high magnetic induction non-oriented silicon steel according to claim 3, characterized in that: The Ca content after the calcium treatment is 0.001-0.005%.

5. The method for producing normalized low iron loss high magnetic induction non-oriented silicon steel according to claim 3, characterized in that: The Ca content after the calcium treatment is 0.002-0.004%.

6. The method for manufacturing normalized low iron loss high magnetic induction non-oriented silicon steel according to claim 3, characterized in that: The high temperature hot rolling and coiling specifically comprises: heating the continuous casting slab to 1100-1180° C., and rolling it into hot coils according to a process of a final rolling temperature of 820-900° C. and a coiling temperature of 560-650° C.

7. The method for manufacturing normalized low iron loss high magnetic induction non-oriented silicon steel according to claim 3, characterized in that: The annealing is specifically: high temperature, short time, rapid annealing, and the annealing temperature is in the range of 880-1000°C.

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