Method for producing ordinary oriented silicon steel

Abstract

The present application provides a method for producing common oriented silicon steel, comprising the following steps: providing a slab, heating, descaling, controlled rolling, controlled cooling, laminar cooling and coiling the slab in sequence to obtain common oriented silicon steel; the controlled cooling step comprises: rapidly cooling the silicon steel after finish rolling to below 850°C, and the cooling rate is 150-400°C / s. The common oriented silicon steel can be prepared using a medium-temperature slab heating process, has lower iron loss and higher magnetic polarization intensity, and meets the national standard for the performance requirements of common oriented silicon steel.

Description

Technical Field

[0001] The present application relates to the technical field of steel production, and in particular to a high magnetic induction oriented silicon steel and a manufacturing method and product thereof. Background Art

[0002] Oriented silicon steel is the "crown" of steel industry products and is the core material for manufacturing ultra-high voltage AC / DC transformers, high-efficiency and energy-saving distribution transformers, converter valve saturated reactors and other power equipment.

[0003] According to the performance, oriented silicon steel can be divided into high magnetic induction oriented silicon steel (HiB) and common oriented silicon steel (CGO). Common oriented silicon steel produced by traditional methods has higher steel loss and slightly worse magnetic induction. Summary of the invention

[0004] The embodiments of the present application provide a method for producing common oriented silicon steel, which can improve the magnetic properties of oriented silicon steel.

[0005] The method for producing ordinary oriented silicon steel provided in the embodiment of the present application comprises the following steps:

[0006] Providing a slab, and sequentially heating, descaling, controlled rolling, controlled cooling and coiling the slab to obtain common oriented silicon steel;

[0007] The step of controlling cooling includes: rapidly cooling the silicon steel after finish rolling to below 850° C., with a cooling rate of 150° C. / s to 400° C. / s.

[0008] In some embodiments of the present application, controlling the rolling process includes:

[0009] Rough rolling, the rough rolling final rolling temperature is required to be ≥1080℃, the rough rolling passes are 5 passes, and after rough rolling, the intermediate billet thickness is 38mm~50mm;

[0010] Finishing rolling, the final rolling temperature is 920℃~1050℃, and the rolling tension is 1-15MPa.

[0011] In some embodiments of the present application, the heating includes: heating the slab at 1280° C. to 1320° C. for more than 200 minutes to obtain a heated slab.

[0012] In some embodiments of the present application, descaling includes: high-pressure water descaling pressure ≥ 20 MPa, and descaling time is 7s to 10s.

[0013] In some embodiments of the present application, the coiling temperature is 450°C to 650°C.

[0014] The technical solution of the present application is a further improvement on the production method of ordinary oriented silicon steel, mainly in that the ultra-fast cooling process is used to quickly cool the strip steel obtained by fine rolling, so that the strip steel is quickly cooled from the high final rolling temperature to below the peak temperature of inhibitor precipitation, reducing the precipitation of coarse second-phase particles during the slow cooling process, and reducing the peak temperature of inhibitor precipitation, thereby refining the size of the two-phase particles of oriented silicon steel as an inhibitor, improving the inhibition ability, and ultimately improving the magnetic properties of the finished product. At the same time, due to the fast cooling speed and rapid temperature drop of ultra-fast cooling, the recovery and recrystallization time of the grains after rolling is shortened, the recovery and recrystallization degree of the grains after rolling is suppressed, the iron loss is further reduced and the magnetic induction is improved, which can improve the high grade rate of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0016] Figure 1 is the iron loss value P of Example 1 and Comparative Example 1 1.7 / 50 .

[0017] Figure 2 is the magnetic induction J of Example 1 and Comparative Example 1 800 .

[0018] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0019] The various embodiments or implementation schemes in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments.

[0020] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the implementation or examples are included in at least one implementation or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same implementation or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more implementations or examples in a suitable manner.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0022] Oriented silicon steel is the "crown" of steel industry products and is the core material for manufacturing ultra-high voltage AC / DC transformers, high-efficiency and energy-saving distribution transformers, converter valve saturated reactors and other power equipment.

[0023] According to the performance, oriented silicon steel can be divided into high magnetic induction oriented silicon steel (HiB) and common oriented silicon steel (CGO). Common oriented silicon steel produced by traditional methods has higher steel loss and slightly worse magnetic induction.

[0024] The inventors of the present application noticed that in the prior art, silicon steel strips are cooled by ordinary laminar cooling after finish rolling, and the cooling rate of ordinary laminar cooling is generally below 100°C / s. Coarse second phase particles are easily precipitated during the slow cooling process, and the ability to hinder the migration of primary recrystallization grain boundaries is weak. It is difficult to limit the average size of the primary recrystallization grains, thereby affecting the magnetic properties of the finished product.

[0025] In view of this, the inventors of the present application have improved the method for producing ordinary oriented silicon steel, thereby reducing the precipitation of coarse second-phase particles during the cooling process and lowering the peak temperature of inhibitor precipitation, thereby refining the size of the two-phase particles of oriented silicon steel as inhibitors, improving the inhibition ability, and ultimately improving the magnetic properties of the finished product.

[0026] The method for producing ordinary oriented silicon steel provided in the embodiment of the present application comprises the following steps:

[0027] Providing a slab, and sequentially heating, descaling, controlled rolling, controlled cooling and coiling the slab to obtain common oriented silicon steel;

[0028] The step of controlling cooling includes: rapidly cooling the silicon steel after finish rolling to below 850° C., with a cooling rate of 150° C. / s to 400° C. / s.

[0029] The technical solution of the present application is a further improvement on the production method of ordinary oriented silicon steel, mainly in that the ultra-fast cooling process is used to quickly cool the strip steel obtained by fine rolling, so that the strip steel is quickly cooled from the high final rolling temperature to below the peak temperature of inhibitor precipitation, reducing the precipitation of coarse second-phase particles during the slow cooling process, and reducing the peak temperature of inhibitor precipitation, thereby refining the size of the two-phase particles of oriented silicon steel as an inhibitor, improving the inhibition ability, and ultimately improving the magnetic properties of the finished product. At the same time, due to the fast cooling speed and rapid temperature drop of ultra-fast cooling, the recovery and recrystallization time of the grains after rolling is shortened, the recovery and recrystallization degree of the grains after rolling is suppressed, the iron loss is further reduced and the magnetic induction is improved, which can improve the high grade rate of the final product.

[0030] The present application can directly use the obtained slabs, and can also obtain the slabs through converter smelting, refining, and continuous casting.

[0031] The method provided in the embodiment of the present application is applicable to ordinary oriented silicon steel.

[0032] Exemplarily, in some embodiments, the slab of ordinary oriented silicon steel includes the following components in percentage by mass: C: 0.020% to 0.060%, Si: 2.80% to 3.40%, Als: 0.010% to 0.035%, N: 0.006% to 0.01%, Mn: 0.05% to 0.1%, S: 0.003% to 0.010%, P: 0.01% to 0.020%, and the rest are iron and unavoidable impurities.

[0033] The ultra-fast cooling process can use ultra-fast cooling equipment. In this regard, the ultra-fast cooling process has the effect of efficiently removing the steam film attached to the surface of the steel plate. It is a kind of efficient cooling method. The cooling speed of the strip is much faster than laminar cooling. For a strip with a thickness of 4.0 mm, the maximum cooling rate of ultra-fast cooling can reach 400°C / s, so the cooling speed is much higher than the conventional laminar cooling. Therefore, the inventor uses the ultra-fast cooling process to cool the strip after finishing rolling, cooling it to 750°C~850°C at 150°C / s~400°C / s, so that the hot-rolled steel plate is quickly reduced from the final rolling temperature to below the peak temperature of inhibitor precipitation, thereby reducing the formation of coarse two-phase particles during the slow cooling process, thereby refining the size of the two-phase particles as inhibitors in oriented silicon steel.

[0034] Comparing the performance of ordinary oriented silicon steel produced by the method provided in the embodiments of the present application with that of hot coils produced by conventional laminar cooling, the performance of the finished steel coils produced by ultra-fast cooling is superior to that produced by conventional laminar flow in terms of iron loss and magnetic induction, and the high grade rate of the final product can be increased.

[0035] It should be noted that the technical solution of the present application does not further limit the specific condition parameters of other steps, and those skilled in the art can make corresponding choices based on the existing technology.

[0036] In some embodiments, controlling the rolling process includes:

[0037] Rough rolling, the rough rolling final rolling temperature is required to be ≥1080℃, the rough rolling passes are 5 passes, and after rough rolling, the intermediate billet thickness is 38mm~50mm;

[0038] Finishing rolling, the final rolling temperature is 920℃~1050℃, and the rolling tension is 1-15MPa.

[0039] According to the embodiments of the present application, the final rolling temperature is 920°C to 1050°C in order to prevent the two-phase particles acting as inhibitors in the slab from aggregating and becoming coarse during the finishing rolling process, thereby reducing the inhibition ability and ultimately leading to a reduction in the magnetic induction performance of the oriented silicon steel. Therefore, the final rolling temperature needs to be controlled to be 920°C to 1050°C.

[0040] In some embodiments of the present application, the heating includes: heating the slab at 1280° C. to 1320° C. for more than 200 minutes to obtain a heated slab.

[0041] According to the embodiments of the present application, in order to fully dissolve the coarse inhibitor grains in the slab and better precipitate fine dispersed two-phase grains during the hot rolling process, the slab needs to be heated at 1280°C to 1320°C for more than 200 minutes to fully dissolve the inhibitor.

[0042] In some embodiments of the present application, descaling includes: high-pressure water descaling pressure ≥ 20 MPa, and descaling time is 7s to 10s.

[0043] Oriented silicon steel slabs are oxidized in a medium to high temperature environment, forming a dense layer of iron oxide (scale) on the surface. This layer of iron oxide needs to be removed before controlled rolling. Otherwise, in the subsequent rolling process, the iron oxide will be rolled into the surface of the oriented silicon steel by the rollers, accelerating the wear of the rollers and affecting the service life.

[0044] In some embodiments of the present application, the coiling temperature is 450°C to 650°C.

[0045] In some of the above embodiments, the hot-rolled steel plate is cooled to 750°C~850°C by an ultra-fast cooling process at 150°C / s~400°C / s, and then cooled to 450°C~650°C by a laminar cooling process at 50°C / s~100°C / s. Fine dispersed two-phase grains can be obtained as inhibitors, which can effectively improve the inhibitory effect of the inhibitor, thereby improving the magnetic induction properties of the oriented silicon steel.

[0046] The following examples are used to further illustrate the method for producing ordinary oriented silicon steel of the present application, but the present application is not limited to these examples. It should be noted that in the following specific examples, conditions and parameters not explicitly specified can be determined by those skilled in the art according to the prior art and are not described in detail here.

[0047] The core loss P of high magnetic induction oriented silicon steel is measured using GB / T 13789-2008 "Method for measuring magnetic properties of electrical steel sheets (strips) using a single-piece tester" 1.7 / 50 and the magnetic polarization intensity J 800 .

[0048] Example 1

[0049] Providing common oriented silicon steel slabs;

[0050] The slab is heated at 1300°C for 320 min to obtain a heated slab;

[0051] The heated slab is descaled, rough rolled and finished rolled to obtain a hot rolled steel plate, wherein the final rolling temperature is 950°C;

[0052] The hot-rolled steel plate is first cooled to 800°C by ultra-fast cooling at 200-250°C / s, and then cooled to 560°C by laminar cooling at 50-100°C / s, and ordinary oriented silicon steel is obtained by coiling.

[0053] Comparative Example 1

[0054] Providing common oriented silicon steel slabs;

[0055] The slab is heated at 1300°C for 320 min to obtain a heated slab;

[0056] The heated slab is descaled, rough rolled and finished rolled to obtain a hot rolled steel plate, wherein the final rolling temperature is 950°C;

[0057] The hot rolled steel plate is cooled to 560°C at 50-100°C / s by laminar cooling process, and ordinary oriented silicon steel is obtained by coiling.

[0058] Core loss P of high magnetic induction oriented silicon steel 1.7 / 50 and the magnetic polarization intensity J 800 Test, the results are as follows Figure 1 and Figure 2 shown.

[0059] Depend on Figure 2 It can be seen that the average magnetic induction of the steel coil produced by ultra-fast cooling in Example 1 is 0.024T higher.

[0060] Depend on Figure 1 and Figure 2It can be seen that the finished product performance of steel coils produced by ultra-fast cooling is superior to that of steel coils produced by conventional laminar flow in terms of both iron loss and magnetic induction.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for producing ordinary oriented silicon steel, characterized in that: The following steps are involved: Providing a slab, and sequentially heating, descaling, controlled rolling, controlled cooling, laminar cooling and coiling the slab to obtain common oriented silicon steel; The controlled cooling step includes: rapidly cooling the silicon steel after controlled rolling to below 850° C., and the controlled cooling speed is 200° C. / s to 250° C. / s; The laminar cooling step includes: the laminar cooling speed is 50-100°C / s.

2. The method for producing common oriented silicon steel according to claim 1, characterized in that: The controlled rolling process comprises: Rough rolling, the rough rolling final rolling temperature is required to be ≥1080°C, the rough rolling passes are 5 passes, and after rough rolling, the intermediate billet thickness is 38mm-50mm; Finish rolling, the final rolling temperature of the finishing rolling is 920℃~1050℃, and the rolling tension is 1-15MPa.

3. The method for producing common grain-oriented silicon steel according to claim 1, characterized in that: The heating comprises: The slab is heated at 1280° C. to 1320° C. for more than 200 minutes to obtain a heated slab.

4. The method for producing common grain-oriented silicon steel according to claim 1, characterized in that: The descaling includes: high-pressure water descaling pressure ≥ 20MPa, and descaling time is 7s to 10s.

5. The method for producing common grain-oriented silicon steel according to claim 1, characterized in that: The coiling temperature is 450°C to 650°C.

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