A method for controlling the particle size of inclusions

Abstract

The present application relates to the technical field of steel smelting, and in particular to a method for controlling the particle size of inclusions; the method comprises: adding a first alloy to molten steel tapped from a converter for preliminary deoxidation to reach a first target dissolved oxygen content, thereby obtaining a first deoxidized molten steel; adding a second alloy to the first deoxidized molten steel for final deoxidation to reach a second target dissolved oxygen content, thereby obtaining a second deoxidized molten steel; refining and degassing the second deoxidized molten steel, and then feeding a magnesium-containing metal; wherein the deoxidation capacity of the first alloy is less than the deoxidation capacity of the second alloy; the first target dissolved oxygen content is 50ppm to 150ppm in terms of parts per million, and the second target dissolved oxygen content is 1ppm to 3ppm in terms of parts per million; performing preliminary deoxidation using the first alloy having a relatively weak deoxidation capacity, and controlling the target oxygen content of the preliminary deoxidation to be 50ppm to 150ppm, and then performing final deoxidation using the second alloy having a relatively strong deoxidation capacity, and finally adding the magnesium-containing metal to the molten steel to achieve control of large-sized inclusions.

Description

Technical Field

[0001] The present application relates to the technical field of steel smelting, and in particular to a method for controlling the particle size of inclusions. Background Art

[0002] The defects caused by inclusions in steel are one of the main factors affecting the quality of steel, especially in high-end special steel, automobile outer panels, DI materials, etc. The current principle of reducing the harm of inclusions is: on the one hand, to remove inclusions as much as possible, and on the other hand, to plasticize inclusions to avoid the appearance of large hard and brittle inclusions.

[0003] At present, the treatment methods for the above two aspects include: removing inclusions by stirring, calming, circulating, and catching bubbles in the molten steel, and modifying the inclusions by calcium treatment to improve the plasticity of the inclusions. However, these methods have not been able to control the size of inclusions from the source of the molten steel. They only make it easier to remove the molten steel inclusions, and do not control large-sized inclusions, which are the key factors that endanger the performance of steel.

[0004] Therefore, how to control large-sized inclusions from the source of molten steel is a technical problem that needs to be solved urgently. Summary of the invention

[0005] The present application provides a method for controlling the particle size of inclusions to solve the technical problem in the prior art that large-sized inclusions are difficult to control from the source of molten steel.

[0006] In a first aspect, the present application provides a method for controlling the particle size of inclusions, for controlling inclusions in molten steel during an off-furnace refining process, the method comprising:

[0007] Adding a first alloy to molten steel tapped from a converter for preliminary deoxidation, so that the oxygen content of the molten steel reaches a first target dissolved oxygen content, thereby obtaining a first deoxidized molten steel;

[0008] adding a second alloy to the first deoxidized molten steel for final deoxidation, so that the oxygen content of the first deoxidized molten steel reaches a second target dissolved oxygen content, thereby obtaining a second deoxidized molten steel;

[0009] The second deoxidized molten steel is refined and degased, and then magnesium-containing metal is fed to control the size of inclusions from the source of the molten steel;

[0010] wherein the deoxidation capacity of the first alloy is less than the deoxidation capacity of the second alloy;

[0011] The first target dissolved oxygen content is 50 ppm to 150 ppm, and the second target dissolved oxygen content is 1 ppm to 3 ppm.

[0012] Optionally, the first alloy comprises ferrosilicon alloy.

[0013] Optionally, the first alloy includes ferrosilicon alloy, and the addition amount of the first alloy is m SiFe In kilograms, it satisfies:

[0014] m SiFe =0.0032×[Si]×△[O]×m s ×10 4 ,

[0015] Wherein, [Si] is the silicon content of the ferrosilicon alloy in percentage, Δ[O] is the difference between the oxidation content of the molten steel in percentage and the first target dissolved oxygen content, m s is the weight of the molten steel in tons.

[0016] Optionally, the second alloy comprises titanium-iron alloy.

[0017] Optionally, the second alloy comprises a titanium-iron alloy, and the amount of the second alloy added is m TiFe In kilograms, it satisfies:

[0018] m TiFe =0.0039×[Ti]×[O]×m s ×10 4 ,

[0019] Wherein, [Ti] is the titanium content of the titanium-iron alloy in percentage, [O] is the oxygen content of the first deoxidized steel liquid in percentage, m s is the weight of the first deoxidized molten steel in tons.

[0020] Optionally, the magnesium-containing metal includes at least one of magnesium, magnesium-aluminum alloy, magnesium-manganese alloy and magnesium-zinc-zirconium alloy.

[0021] Optionally, the feeding rate of the magnesium-containing metal is 3 m / s to 5 m / s.

[0022] Optionally, the amount of magnesium-containing metal added is 100g to 150g per ton of molten steel.

[0023] Optionally, before adding the first alloy to the molten steel tapped from the converter, and then performing preliminary deoxidation to a first target dissolved oxygen content to obtain a first deoxidized molten steel, the method further comprises:

[0024] The molten steel discharged from the converter is subjected to a circulating treatment of off-furnace refining so that the oxygen content of the molten steel is controlled to 300ppm to 500ppm in parts per million.

[0025] Optionally, the vacuum degree of the cyclic treatment is 4000Pa to 6000Pa.

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] The embodiment of the present application provides a method for controlling the particle size of inclusions. During the refining process outside the furnace, a first alloy with a weaker deoxidation ability is used for preliminary deoxidation, and the target oxygen content of the preliminary deoxidation is controlled at 50ppm-150ppm, so that most of the oxygen in the molten steel exists in the form of oxygen-containing inclusions, and the degree of aggregation between the inclusions is low, and the remaining oxygen in the molten steel is finally deoxidized by the second alloy with a stronger deoxidation ability. Since the oxygen content is low at 50ppm-150ppm at this time, the oxygen-containing inclusions formed by the active metal in the second alloy can be refined, and then magnesium-containing metal is added to the molten steel. Since magnesium can further combine with oxygen in the molten steel, the oxygen in the molten steel is further removed. At the same time, since magnesium can also combine with oxygen-containing inclusions and increase the fluidity of the molten steel, there is no repulsion reaction between the oxygen-containing inclusions formed during the refining process, so that the inclusions are not easy to aggregate and grow, and the fine inclusion morphology is maintained, so that large-sized inclusions can be controlled from the source of the molten steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0030] Figure 1 A schematic diagram of a process for a method provided in an embodiment of the present application;

[0031] Figure 2 A detailed flowchart of the method provided in the embodiment of the present application. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below in conjunction with specific implementations and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementations and examples are for illustrating the present invention, rather than limiting the present invention.

[0033] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0034] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0035] The technical solution provided by the embodiment of the present invention is to solve the above technical problems, and the overall idea is as follows:

[0036] In one embodiment of the present application, Figure 1 As shown, a method for controlling the particle size of inclusions is provided to control the inclusions in molten steel during the refining process outside the furnace, and the method comprises:

[0037] S1. Adding a first alloy to the molten steel from the converter for preliminary deoxidation, so that the oxygen content of the molten steel reaches a first target dissolved oxygen content, to obtain a first deoxidized molten steel;

[0038] S2. adding a second alloy to the first deoxidized molten steel for final deoxidation, so that the oxygen content of the first deoxidized molten steel reaches a second target dissolved oxygen content to obtain a second deoxidized molten steel;

[0039] S3. The second deoxidized molten steel is refined and broken, and then fed with magnesium-containing metal to achieve control of the size of inclusions from the source of the molten steel;

[0040] wherein the deoxidation capacity of the first alloy is less than the deoxidation capacity of the second alloy;

[0041] The first target dissolved oxygen content is 50 ppm to 150 ppm, and the second target dissolved oxygen content is 1 ppm to 3 ppm.

[0042] In the embodiment of the present application, the positive effect of controlling the deoxidation ability of the first alloy to be weaker than that of the second alloy is that the molten steel is first preliminarily deoxidized by the first alloy with weaker deoxidation ability, so that the oxygen content of the molten steel is initially reduced and oxygen-containing inclusions are formed, and then the molten steel is finally deoxidized by the second alloy to refine the formed oxygen-containing inclusions, thereby facilitating the subsequent combination of magnesium in the magnesium-containing metal with the oxygen-containing inclusions.

[0043] The positive effect of the first target dissolved oxygen content being 50ppm to 150ppm is that within this range of dissolved oxygen content, the molten steel can be kept at a low oxygen content, thereby avoiding the more active metal in the second alloy from first forming inclusions and then refining the inclusions, resulting in insufficient inclusion refinement.

[0044] The positive effect of the second target dissolved oxygen content of 1 ppm to 3 ppm is that within this dissolved oxygen content range, the magnesium-containing metal can combine with oxygen and then with inclusions, thereby avoiding excessive consumption of the magnesium-containing metal under conditions of higher oxygen content.

[0045] In order to make the added alloys react completely with the molten steel, the first deoxidized molten steel after the preliminary deoxidation treatment can also be vacuum circulated for 1min to 3min. Similarly, the second deoxidized molten steel after the final deoxidation can also be vacuum circulated for 2min to 4min.

[0046] In order to synchronously adjust the deoxidation and alloying of the molten steel, after the second deoxidized molten steel is vacuum circulated for 2 to 4 minutes, the second alloy can be added to the second deoxidized molten steel after vacuum circulation for alloying according to the actual molten steel added and the requirements of the steel product, and then vacuum circulated for another 2 to 4 minutes. Similarly, after the first deoxidized molten steel is vacuum circulated for 1 to 3 minutes, the first alloy can be added to the first deoxidized molten steel after vacuum circulation for alloying according to the actual molten steel added and the requirements of the steel product.

[0047] In order to better control the reaction process of magnesium-containing metal and inclusions, during the process of feeding magnesium-containing metal, the ladle can also be stirred by bottom blowing with argon gas, and the intensity of bottom blowing is controlled at 0.2NL / min·t -1 ~0.5NL / min·t -1 After the feeding of magnesium-containing metal is completed, the soft blowing operation will no longer be performed.

[0048] In some optional embodiments, the first alloy includes ferrosilicon alloy.

[0049] In the embodiment of the present application, the positive effect of controlling the type of the first alloy is that the deoxidation ability of the first alloy can be weaker than that of the second alloy, while no other impurities are introduced into the molten steel, thereby forming oxygen-containing inclusions, which facilitates the subsequent refinement of the second alloy.

[0050] In some optional embodiments, the first alloy includes ferrosilicon alloy, and the addition amount m of the first alloy is SiFe In kilograms, it satisfies:

[0051] m SiFe =0.0032×[Si]×△[O]×m s ×10 4 ,

[0052] Wherein, [Si] is the silicon content of the ferrosilicon alloy in percentage, Δ[O] is the difference between the oxidation content of the molten steel in percentage and the first target dissolved oxygen content in percentage, m sis the weight of the molten steel in tons.

[0053] In the embodiment of the present application, the specific relationship for controlling the amount of the first alloy to be added is based on the silicon content in the first alloy, the oxygen content to be removed and the weight of the molten steel, so that the amount of addition can be accurately calculated when the first alloy is a ferrosilicon alloy.

[0054] In some optional embodiments, the second alloy comprises titanium-iron alloy.

[0055] In the embodiment of the present application, the positive effect of controlling the type of the second alloy is that the deoxidation ability of the second alloy is stronger than that of the first alloy. At the same time, the active metal in the second alloy can effectively refine the inclusions, thereby reducing the presence of large-sized inclusions.

[0056] In some optional embodiments, the second alloy comprises a titanium-iron alloy, and the amount of the second alloy added is m TiFe In kilograms, it satisfies:

[0057] m TiFe =0.0039×[Ti]×[O]×m s ×10 4 ,

[0058] Wherein, [Ti] is the titanium content of the titanium-iron alloy in percentage, [O] is the oxygen content of the first deoxidized steel liquid in percentage, m s is the weight of the first deoxidized molten steel in tons.

[0059] In the embodiment of the present application, the specific relationship for controlling the amount of the second alloy added is based on the titanium content in the second alloy, the first deoxidation content and the weight of the first deoxidized steel liquid, so that the amount of the second alloy added when it is a titanium-iron alloy can be accurately obtained, so that the active metal of the second alloy can effectively refine the inclusions.

[0060] In some optional embodiments, the magnesium-containing metal includes at least one of magnesium, magnesium-aluminum alloy, magnesium-manganese alloy and magnesium-zinc-zirconium alloy.

[0061] In the embodiments of the present application, the type of magnesium-containing metal is controlled, and the magnesium element in the magnesium-containing metal can not only combine with oxygen to form oxygen-containing inclusions, further reducing the oxygen content, but also combine with oxygen-containing inclusions, so that there is no repulsive reaction between the oxygen-containing inclusions formed in the refining process, thereby making it difficult for the inclusions to aggregate and grow, and maintaining a fine inclusion morphology.

[0062] In some optional embodiments, the feeding rate of the magnesium-containing metal is 3 m / s to 5 m / s.

[0063] In the embodiment of the present application, the positive effect of the feeding rate of the magnesium-containing metal being 3 m / s to 5 m / s is that within the range of the feeding rate, since the reaction of magnesium in the magnesium-containing metal is relatively violent, the reaction speed of magnesium can be controlled by controlling the feeding rate, thereby easing the reaction of magnesium and allowing the magnesium to react fully.

[0064] In some optional embodiments, the amount of magnesium-containing metal added is 100 g to 150 g per ton of molten steel.

[0065] In the embodiment of the present application, the amount of magnesium metal added is 100g to 150g per ton of molten steel. The positive effect is that within the range of the added amount, magnesium can effectively react with oxygen in the molten steel to obtain inclusions. At the same time, magnesium can also increase the fluidity of the molten steel, so that there is no repulsive reaction between the oxygen-containing inclusions formed during the refining process, thereby making it difficult for the inclusions to aggregate and grow, maintaining the fine inclusion morphology, thereby achieving control of large-sized inclusions from the source of the molten steel.

[0066] In some optional embodiments, before adding the first alloy to the molten steel tapped from the converter, and then performing preliminary deoxidation to a first target dissolved oxygen content to obtain a first deoxidized molten steel, the process further includes:

[0067] S101. The molten steel discharged from the converter is subjected to a circulation treatment of external refining to control the oxygen content of the molten steel to 300ppm to 500ppm.

[0068] In the embodiments of the present application, the positive effect of controlling the oxygen content of the molten steel to 300ppm to 500ppm is that adding ferrosilicon alloy under this oxygen content condition can initially generate large-sized silicon oxides, which is beneficial to the removal of initial large-sized inclusions.

[0069] In some optional embodiments, the vacuum degree of the cyclic treatment is 4000Pa to 6000Pa.

[0070] In the embodiment of the present application, the positive effect of the vacuum degree of the circulation treatment being 4000Pa to 6000Pa is that circulation under this vacuum degree can not only ensure the circulation volume of the molten steel and the effect of removing gas, but also prevent the volatilization of the magnesium element caused by excessively low vacuum degree.

[0071] In order to better control the changes in the size and oxygen content of the slag in the molten steel, during the refining process outside the furnace, the Al2O3 content in the ladle top slag is controlled at 13% to 18%, and the Al content in the molten steel is controlled below 0.002%.

[0072] Example 1

[0073] Low carbon alloy steel was used as the experimental steel type, and its main components are shown in Table 1.

[0074] Table 1 Steel composition of low carbon alloy steel

[0075] C(％) Si(%) Mn(%) P(％) S(％) Alt(%) Ti(%) 0.07～0.08 ≤0.15 1.2～1.3 ≤0.010 ≤0.012 ≤0.0050 0.050～0.060

[0076] After the steel grades in Table 1 are tapped from the converter, the oxygen content at the converter end point is 642ppm, and the weight of the molten steel at the converter end point is 224t.

[0077] like Figure 1 As shown, a method for controlling the particle size of inclusions comprises:

[0078] S101. The molten steel from the converter is subjected to a refining cycle outside the furnace so that the oxygen content of the molten steel is controlled to 300ppm to 500ppm in parts per million, wherein the vacuum degree of the circulation process is 4000Pa and the target dissolved oxygen content of the circulation process is 498ppm;

[0079] S1. Adding a first alloy to the molten steel from the converter for preliminary deoxidation, so that the oxygen content of the molten steel reaches a first target dissolved oxygen content, to obtain a first deoxidized molten steel;

[0080] S2. Adding a second alloy to the first deoxidized molten steel for final deoxidation, so that the oxygen content of the first deoxidized molten steel reaches a second target dissolved oxygen content, to obtain a second deoxidized molten steel;

[0081] S3. The second deoxidized molten steel is refined and broken, and then fed with magnesium-containing metal. After the feeding is completed, no soft blowing operation is performed to achieve control of the size of inclusions from the source of the molten steel;

[0082] Wherein, the deoxidation capacity of the first alloy is less than the deoxidation capacity of the second alloy;

[0083] The first target dissolved oxygen content is 80 ppm, and the second target dissolved oxygen content is 1 ppm to 3 ppm.

[0084] The first alloy is a ferrosilicon alloy, and the addition amount of the first alloy is m SiFe In kilograms, it satisfies:

[0085] m SiFe =0.0032×[Si]×△[O]×m s ×10 4 ,

[0086] Wherein, [Si] is the silicon content of ferrosilicon alloy in percentage, and the actual measured value is 70%. △[O] is the difference between the oxidation content of molten steel in percentage and the first target dissolved oxygen content, and the actual measured value is 0.0409%. s is the weight of the molten steel in tons, that is, the weight of the molten steel at the end of the converter is 224t.

[0087] According to the formula, the amount of ferrosilicon alloy added is 205 kg. However, after the first deoxidized steel liquid circulates for 3 minutes, 505 kg of ferrosilicon alloy needs to be added. Therefore, a total of 710 kg of ferrosilicon alloy is added at one time. After 3 minutes of vacuum circulation, the actual dissolved oxygen content of the first deoxidized steel liquid is 75 ppm.

[0088] The second alloy is a titanium-iron alloy, and the addition amount of the second alloy is m TiFe In kilograms, it satisfies:

[0089] m TiFe =0.0039×[Ti]×[O]×m s ×10 4 ,

[0090] Wherein, [Ti] is the titanium content of the ferro-titanium alloy in percentage, and the actual measured titanium content is 69% (the titanium content in the general ferro-titanium alloy is 70% ± 2% fluctuation), [O] is the oxygen content of the first deoxidized steel liquid in percentage, and the actual measured value is 0.0075%, m s The weight of the first deoxidized molten steel in tons is the weight of the molten steel at the end of the converter, 224t.

[0091] According to the formula, the amount of ferrotitanium alloy added is 46 kg. However, after the second deoxidized steel liquid circulates for 2 minutes, 168 kg of ferrotitanium alloy needs to be added for alloying. Therefore, a total of 214 kg of ferrotitanium alloy needs to be added at one time.

[0092] The magnesium-containing metal is a magnesium-aluminum alloy, wherein the magnesium content is 20%.

[0093] The feeding rate of magnesium-containing metal is 5 m / s.

[0094] The amount of magnesium metal added is 143 g per ton of molten steel, that is, the length of the added magnesium-aluminum alloy wire is 300 m.

[0095] The Al2O3 content in the ladle top slag is controlled at 15%, and the Al content in the molten steel is controlled at 0.0015%.

[0096] Example 2

[0097] Comparing Example 2 with Example 1, the difference between Example 2 and Example 1 is:

[0098] The first target dissolved oxygen level was 54 ppm.

[0099] The feed rate of magnesium-containing metal is 3.3 m / s.

[0100] The amount of magnesium metal added is 104 g per ton of molten steel.

[0101] The vacuum degree of the circulation treatment is 4000Pa, and the target dissolved oxygen content of the circulation treatment is 2ppm.

[0102] Example 3

[0103] Comparing Example 3 with Example 1, the difference between Example 3 and Example 1 is:

[0104] The first target dissolved oxygen level was 141 ppm.

[0105] The feed rate of the magnesium-containing metal is 5.0 m / s.

[0106] The amount of magnesium metal added is 149 g per ton of molten steel.

[0107] The vacuum degree of the circulation treatment is 6000Pa, and the target dissolved oxygen content of the circulation treatment is 1ppm.

[0108] Comparative Example 1

[0109] Comparative Example 1 and Example 1 are compared. The difference between Comparative Example 1 and Example 1 is:

[0110] Both the first alloy and the second alloy are ferrosilicon alloys.

[0111] Comparative Example 2

[0112] Comparative Example 2 and Example 1 are compared. The difference between Comparative Example 2 and Example 1 is:

[0113] The first alloy and the second alloy are both titanium-iron alloys.

[0114] Comparative Example 3

[0115] Comparative Example 3 and Example 1 are compared. The difference between Comparative Example 3 and Example 1 is:

[0116] The first target dissolved oxygen level was 200 ppm.

[0117] The feeding rate of magnesium-containing metal is 3 m / s.

[0118] The amount of magnesium metal added is 140g per ton of molten steel.

[0119] The vacuum degree of the circulation treatment is 4000Pa, and the target dissolved oxygen content of the circulation treatment is 2ppm.

[0120] Comparative Example 4

[0121] Comparative Example 4 and Example 1 are compared. The difference between Comparative Example 4 and Example 1 is:

[0122] The first target dissolved oxygen level was 70 ppm.

[0123] The feed rate of magnesium-containing metal is 4 m / s.

[0124] The amount of magnesium metal added is 140g per ton of molten steel.

[0125] The vacuum degree of the circulation treatment is 100Pa, and the target dissolved oxygen content of the circulation treatment is 2ppm.

[0126] Related experiments:

[0127] The final steel coils obtained by various embodiments and comparative examples were collected, wherein the process coils produced by the traditional process were used as blank controls, and the results of the inclusion number density were tested as shown in Table 2.

[0128] Test methods for related experiments:

[0129] Inclusion number density: The inclusion number density analysis was carried out using Aspex inclusion automatic scanning electron microscope, and the analysis area of ​​each sample was 100mm 2 .

[0130] Table 2

[0131]

[0132]

[0133] Detailed analysis of Table 2:

[0134] The inclusion number density refers to the aggregation of inclusions within the range of ≥50μm in the steel plate coil. The lower the inclusion number density, the fewer inclusions in the steel plate coil.

[0135] From the data of Examples 1-3, it can be seen that

[0136] By adopting the method of the present application, the first alloy with weaker deoxidation ability is used for preliminary deoxidation, and the target oxygen content of the preliminary deoxidation is controlled at 50ppm-150ppm, so that most of the oxygen in the molten steel exists in the form of oxygen-containing inclusions, and the degree of aggregation between the inclusions is low, and the remaining oxygen in the molten steel is finally deoxidized by the second alloy with stronger deoxidation ability, and the oxygen-containing inclusions formed by the refinement of the active metal in the second alloy are further removed by adding magnesium-containing metal to the molten steel. At the same time, the oxygen-containing inclusions formed in the refining process do not have a rejection reaction, and the fine inclusion morphology is maintained, so that the control of large-sized inclusions from the source of the molten steel can be achieved.

[0137] One or more technical solutions in the embodiments of the present application also have at least the following technical effects or advantages:

[0138] (1) The method provided in the embodiment of the present application uses a first alloy with a weaker deoxidation ability to perform preliminary deoxidation, and the target oxygen content of the preliminary deoxidation is controlled at 50ppm to 150ppm, and the remaining oxygen in the molten steel is finally deoxidized by a second alloy with a stronger deoxidation ability. The oxygen-containing inclusions formed by the refinement of the active metal in the second alloy are then added to the molten steel to achieve the control of large-sized inclusions from the source of the molten steel.

[0139] (2) The method provided in the embodiment of the present application can control the size of inclusions produced by deoxidation to about 1 μm through the step-by-step deoxidation of ferrosilicon alloy and ferrotitanium alloy. The addition of magnesium-containing metal can prevent the inclusions from aggregating and growing, thereby avoiding the generation of large-sized inclusions.

[0140] (3) The method provided in the embodiment of the present application reduces the large-sized inclusions ≥50 μm in the final steel plate coil by about 75%.

[0141] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "include..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0142] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0143] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for controlling the particle size of inclusions, characterized in that: The method for controlling inclusions in molten steel during refining outside a furnace comprises: Adding a first alloy to molten steel tapped from a converter for preliminary deoxidation, so that the oxygen content of the molten steel reaches a first target dissolved oxygen content, thereby obtaining a first deoxidized molten steel; adding a second alloy to the first deoxidized molten steel for final deoxidation, so that the oxygen content of the first deoxidized molten steel reaches a second target dissolved oxygen content, thereby obtaining a second deoxidized molten steel; The second deoxidized steel liquid is refined and degased, and then magnesium-containing metal is fed to control the size of inclusions; wherein the deoxidation capacity of the first alloy is less than the deoxidation capacity of the second alloy; The first target dissolved oxygen content is 50 ppm to 150 ppm in parts per million, and the second target dissolved oxygen content is 1 ppm to 3 ppm in parts per million; The first alloy includes ferrosilicon alloy, and the addition amount of the first alloy is m SiFe In kilograms, it satisfies: m SiFe =0.0032×[Si]×△[O]×m s ×10 4 , Wherein, [Si] is the silicon content of the ferrosilicon alloy in percentage, Δ[O] is the difference between the oxidation content of the molten steel in percentage and the first target dissolved oxygen content, m s is the weight of the molten steel in tons; The second alloy comprises titanium-iron alloy, and the addition amount of the second alloy is m TiFe In kilograms, it satisfies: I TiFe =0.0039×[Ti]×[O]×m s ×10 4 , Wherein, [Ti] is the titanium content of the titanium-iron alloy in percentage, [O] is the oxygen content of the first deoxidized steel liquid in percentage, m s is the weight of the first deoxidized molten steel in tons.

2. The method according to claim 1, characterized in that The magnesium-containing metal includes at least one of magnesium, magnesium-aluminum alloy, magnesium-manganese alloy and magnesium-zinc-zirconium alloy.

3. The method according to claim 1, characterized in that The feeding rate of the magnesium-containing metal is 3m / s to 5m / s.

4. The method according to claim 1, characterized in that: The amount of magnesium metal added is 100g to 150g per ton of molten steel.

5. The method according to claim 1, characterized in that The first alloy is added to the molten steel tapped from the converter, and then the molten steel is preliminarily deoxidized to a first target dissolved oxygen content to obtain a first deoxidized molten steel. Prior to this, the method further comprises: The molten steel discharged from the converter is subjected to a circulating treatment of off-furnace refining so that the oxygen content of the molten steel is controlled to 300ppm to 500ppm in parts per million.

6. The method according to claim 5, characterized in that The vacuum degree of the circulation treatment is 4000Pa to 6000Pa.

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