Method for controlling content of Ti element in electroslag remelting hundred-ton 022Cr12Ni10MoTi steel

Abstract

The invention provides a control method for the Ti element content of electroslag remelting hundred-ton-grade 022Cr12Ni10MoTi steel, and belongs to the technical field of electroslag remelting. In order to solve the problem that the content of the Ti element in the electroslag remelting hundred-ton 022Cr12Ni10MoTi steel is difficult to control to be 0.10-0.15%, the control method for the content of the Ti element in the electroslag remelting hundred-ton 022Cr12Ni10MoTi steel comprises the steps that electroslag remelting is conducted in a bipolar series connection mode, a consumable electrode is produced in a vacuum induction and vacuum consumable duplex mode, and the content of the Ti element in the consumable electrode is 0.10-0.17% (wt%); the filling ratio of the consumable electrode to the crystallizer is 0.3-0.35; and the smelting slag is fluorite-white corundum-limestone-fused magnesite-silicon dioxide-titanium dioxide six-element slag. According to the method, through the specially designed consumable electrode and control over the smelting process, the effect that the content of the Ti element of the electroslag remelted hundred-ton-grade 022Cr12Ni10MoTi steel ranges from 0.10% to 0.15% is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of electroslag remelting, and in particular to a method for controlling the Ti element content in electroslag remelting 100-ton grade 022Cr12Ni10MoTi steel. Background Art

[0002] 022Cr12Ni10MoTi steel is a steel ingot required for a certain project. Its chemical composition is as follows:

[0003] Table 1 Chemical composition of 022Cr12Ni10MoTi steel

[0004]

[0005] 022Cr12Ni10MoTi products have high requirements for Ti content in steel. To achieve the optimal performance range, the Ti element content requirement is: 0.10-0.15% (wt%).

[0006] The largest existing 022Cr12Ni10MoTi steel ingot is 10 tons, and the Ti content can be controlled within a range of 0.10-0.15%. However, the crystallizer diameter of these small-tonnage 022Cr12Ni10MoTi steel electroslag remelting (ESR) ingots is small, resulting in short smelting times and a rapid deoxidation reaction, making the Ti content more easily controlled. However, the 100-ton 022Cr12Ni10MoTi steel ESR ingots currently in demand use larger crystallizers and longer smelting times. The slag undergoes prolonged reaction, causing changes in the composition of various components. Furthermore, Ti is highly reactive during the ESR process and can be easily burned away. Therefore, controlling the Ti content within a range of 0.10-0.15% is far more challenging than with smaller-diameter ESR furnaces. Summary of the Invention

[0007] The present application aims to address the prior art issue of difficulty controlling the Ti content of 100-ton grade 022Cr12Ni10MoTi steel within the range of 0.10-0.15% in electroslag remelting. Therefore, the present application provides a method for controlling the Ti content of 100-ton grade 022Cr12Ni10MoTi steel in electroslag remelting. By utilizing specially designed consumable electrodes and controlled smelting processes, the present application achieves a Ti content of 0.10-0.15% in electroslag remelting of 100-ton grade 022Cr12Ni10MoTi steel.

[0008] The embodiment of the present application provides a method for controlling the Ti element content in 100-ton grade 022Cr12Ni10MoTi steel by electroslag remelting, which adopts bipolar series electroslag remelting, and:

[0009] The consumable electrode is produced by vacuum induction + vacuum consumable dual mode, and the Ti element in the consumable electrode is 0.10-0.17% (wt%);

[0010] The filling ratio of consumable electrode and crystallizer is 0.3-0.35;

[0011] The slag used for smelting is a hexavalent slag of fluorite-white corundum-limestone-fused magnesia-silicon dioxide-titanium dioxide.

[0012] In some embodiments, argon gas is used for protection throughout the electroslag remelting process, and a deoxidizer is added to control the environment in the electroslag remelting furnace to a reducing atmosphere.

[0013] In some embodiments, including:

[0014] S1 designed consumable electrode: the Ti element in the consumable electrode is 0.10-0.17% (wt%);

[0015] S2 production of consumable electrodes: using vacuum induction + vacuum consumable double production method;

[0016] S3 smelting preparation: according to the size of consumable electrode, mold size and filling ratio, the consumable electrodes are matched and welded, and the weld is heated and kept warm after welding, with the holding temperature ≥ 200℃;

[0017] CaF2-TiO2 conductive flux is used, and the conductive flux is surrounded by fluorite;

[0018] S4 electroslag remelting: argon protection is used throughout the process, and the flow rate is 200-350m 3 / h;

[0019] During the slag making process, the slag is added in the order of fluorite-white corundum-limestone-fused magnesia-silicon dioxide-titanium dioxide until all the components are melted;

[0020] During the first consumption of the consumable electrode, gradually increase the power until the current reaches 20-35KA and the voltage reaches 120-150V;

[0021] During remelting, Al is added every five minutes for deoxidation, and slag samples are analyzed every hour, and the amount of deoxidizer is adjusted based on the results;

[0022] When the remaining distance from the target weight is less than the first threshold, the power is gradually reduced and the feeding operation is performed;

[0023] When the target weight is reached, the power is turned off, the consumable electrode is raised, and the argon gas is turned off;

[0024] S5 stripping: keep warm for 4-8 hours and then send to heat treatment furnace.

[0025] In some embodiments, S3 further includes treating the surface of the consumable electrode before pairing, and applying a protective coating after the treatment, wherein the protective coating is used to reduce the degree of surface oxidation of the consumable electrode after baking.

[0026] In some embodiments, the paired consumable electrodes are welded using a manual welding J507 electrode method.

[0027] In some embodiments, in S4, the flow rate of argon protection is 300-350m2 in the first 20-30 minutes. 3 / h, then changed to 200-250m 3 / h.

[0028] In some embodiments, in S4, the first threshold is 5-10t.

[0029] Beneficial effects:

[0030] The Ti content of 100-ton grade 022Cr12Ni10MoTi steel after electroslag remelting meets the product requirements. The specific value is: Ti: 0.13-0.15%, which is in line with the product's optimal performance requirements.

[0031] Other features and corresponding beneficial effects of the present application are described in the latter part of the specification, and it should be understood that at least some of the beneficial effects become obvious from the description in the specification of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flowchart of the application. DETAILED DESCRIPTION

[0033] The content of the present invention can be more easily understood by referring to the detailed description of the preferred embodiment of the present invention below and the examples included. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as those of ordinary skill in the art to which the present invention belongs. When there is a contradiction, the definition in this specification shall prevail. As used herein, the term "prepared by..." is synonymous with "comprising". The terms "comprising," "including," "having," "containing," or any other variation thereof used herein are intended to cover non-exclusive inclusions. For example, a composition, step, method, product, or device comprising the listed elements is not necessarily limited to those elements, but may include other elements not explicitly listed or elements inherent to such a composition, step, method, product, or device.

[0034] The conjunction "consisting of" excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim, rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0035] When amount, concentration or other value or parameter is represented with range, preferred range or the range that a series of upper preferred value and lower preferred value limit are expressed, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, no matter whether this range is disclosed separately.For example, when disclosing scope "1 to 5", described scope should be interpreted as including scope "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc.When numerical range is described in this article, unless otherwise stated, otherwise this scope is intended to include its end value and all integers and fractions within this range.

[0036] The singular includes plural references unless the context clearly dictates otherwise. "Optional" or "either" means that the subsequently described event or incident can or cannot occur, and that the description includes instances where the event occurs and instances where it does not.

[0037] Approximating terms in the specification and claims are used to modify a quantity to indicate that the invention is not limited to that specific quantity and includes acceptable modifications close to that quantity that do not result in a change in the relevant basic function. Accordingly, the use of "about," "approximately," or the like to modify a numerical value indicates that the invention is not limited to that exact numerical value. In some instances, approximating terms may correspond to the precision of the instrument used to measure the value. In the specification and claims of this application, range definitions may be combined and / or interchanged, and unless otherwise indicated, such ranges include all subranges contained therein.

[0038] In addition, the indefinite articles "a" and "an" before the elements or components of the present invention do not limit the quantity requirement (i.e., the number of times the elements or components appear). Therefore, "a" or "an" should be interpreted as including one or at least one, and elements or components in the singular also include plural forms, unless the number is obviously intended to be singular.

[0039] In existing technology, small 022Cr12Ni10MoTi ESR ingots are typically produced by increasing the Al content to maintain a low Ti burnout range, for example, 0.10-0.15% Ti. Specifically, during the production of small 022Cr12Ni10MoTi ESR ingots, the small mold diameter and shallow metal pool allow for rapid solidification, reducing reaction time and suppressing Ti burnout while minimizing slag changes. However, large ESR ingots, due to their larger diameter and deeper metal pool, experience slower solidification and significantly longer reaction times, making them impractical to produce in the same manner as small ESR ingots.

[0040] Therefore, an embodiment of the present application provides a method for controlling the Ti element content in 100-ton 022Cr12Ni10MoTi steel electroslag remelting, which adopts bipolar series electroslag remelting. Bipolar series means that two electrodes are arranged vertically, with a slag pool and a molten metal pool in the middle. The current flows from the positive pole of the power supply to the first electrode, through the slag pool to the second electrode, and then returns to the negative pole of the power supply. In this way, a series circuit is formed, the current path is longer, but the resistance heat is more concentrated, the thermal efficiency is high, the melting speed is fast, and the refining effect is good. It is suitable for 100-ton steel ingot electroslag remelting.

[0041] The chemical composition of 022Cr12Ni10MoTi steel is as follows:

[0042]

[0043] This method ensures that the elements after electroslag remelting, especially Ti, are within the range of 0.10-0.15% (wt%) through the special design of the consumable electrode and the control of the electroslag remelting process. Specifically, the consumable electrode is produced using a vacuum induction + vacuum consumable dual method, which can effectively remove gas elements (H, O, N) within the consumable electrode, improving product quality. The Ti content in the consumable electrode is 0.10-0.17% (wt%). The vacuum induction + vacuum consumable production method can ensure a stable Ti yield in the consumable electrode.

[0044] In one embodiment, the filling ratio of the consumable electrode to the crystallizer is 0.3-0.35, such as 0.3, 0.33, 0.34, etc.

[0045] In one embodiment, the smelting slag is a hexavalent slag composed of fluorite, white corundum, limestone, fused magnesia, silica, and titanium dioxide. This slag exhibits excellent fluidity and rapid reaction at 1600°C, while also suppressing Ti burnout. Specifically, titanium dioxide (TiO2) has a chemical equilibrium for Ti oxidation: Ti + O2 = TiO2. Increasing the TiO2 content shifts the equilibrium to the left, effectively suppressing Ti burnout during electroslag remelting. However, excessive TiO2 can exacerbate O transfer, so the TiO2 content is preferably controlled within 0-4%.

[0046] Preferably, the slag ratio is 55%≤CaF2≤70%, 8%≤CaO≤17%, 10%≤Al2O3≤20%, 4%≤SiO2≤8%, 0≤TiO2≤4%, and 0%≤MgO≤2%.

[0047] In one embodiment, argon protection is used throughout the electroslag remelting process to reduce the impact of the external atmosphere on the electroslag remelting process.

[0048] In one embodiment, during the electroslag remelting process, a deoxidizer is added to control the environment in the electroslag remelting furnace to be a reducing atmosphere.

[0049] See Figure 1 , Figure 1 This is a flowchart of the application.

[0050] In one embodiment, the method comprises:

[0051] S1 designed consumable electrode: the Ti element in the consumable electrode is 0.10-0.17% (wt%).

[0052] S2 produces consumable electrodes: it adopts vacuum induction + vacuum consumable electrodes dual production method.

[0053] S3 smelting preparation: according to the consumable electrode size, mold size and filling ratio, the consumable electrodes are matched and welded, and the weld is heated and kept warm after welding, with the holding temperature ≥ 200℃.

[0054] CaF2-TiO2 conductive flux is used, and the conductive flux is surrounded by fluorite.

[0055] Preferably, the consumable electrode surface is treated before pairing, such as by lathing the surface to remove the oxide layer. A protective coating is then applied after treatment to reduce the degree of surface oxidation after baking. The protective coating primarily consists of oxides such as Al2O3.

[0056] Preferably, the paired consumable electrodes are welded using a manual welding J507 electrode method.

[0057] S4 electroslag remelting: argon protection is used throughout the process, and the flow rate is 200-350m 3 / h. Preferably, the flow rate is 300-350m3 / h 20-30min before the argon protection is turned on. 3 / h to quickly exhaust the air and distribute the argon to achieve protection, and then switch to 200-250m 3 / h, to maintain the protective atmosphere.

[0058] During the electric slag making process, the slag is added in the order of fluorite - white corundum - limestone - fused magnesia - silicon dioxide - titanium dioxide until all the components are melted.

[0059] During the first consumption of the consumable electrode, that is, when the graphite electrode is replaced with the consumable electrode, gradually increase the power until the current is 20-35KA and the voltage is 120-150V.

[0060] During remelting, Al is added every five minutes for deoxidation, and slag samples are analyzed every hour, and the amount of deoxidizer is adjusted based on the results.

[0061] When the weight is less than the target weight by a first threshold, the power is gradually reduced and the feeding operation is performed. Preferably, the first threshold is 5-10t.

[0062] When the target weight is reached, the power is turned off, the consumable electrode is raised, and the argon gas is turned off.

[0063] S5 stripping: keep warm for 4-8 hours and then send to heat treatment furnace.

[0064] In one embodiment, the method comprises:

[0065] S1 design consumable electrode:

[0066] 1.1 Design the production method and composition of the consumable electrode. The consumable electrode is required to be produced using a vacuum induction + vacuum consumable electrode dual process. The consumable electrode has a diameter of φ580mm and a length of 2m. The Ti content in the consumable electrode is specified to be 0.10-0.17%;

[0067] S2 produces consumable electrodes:

[0068] 2.1 The consumable electrode is smelted by vacuum induction + vacuum consumable method.

[0069] 2.2 The consumable electrode is inspected and the Ti content of the consumable electrode is required to meet the requirement of 0.10%-0.17% (wt).

[0070] 2.3 The consumable electrode size meets the requirements of diameter φ580mm and length 2m.

[0071] S3 smelting preparation:

[0072] 3.1 After surface treatment, the consumable electrode is coated with special protective coating.

[0073] 3.2 Pair the consumable electrodes, with 4 electrodes as a round, that is, the filling ratio is 0.33, which is compatible with the φ2020 crystallizer, which is conducive to stable production and reduces fluctuations; use manual welding J507 welding rod method for welding; after welding, heat and keep the weld warm, and the insulation temperature is required to be ≥200℃.

[0074] 3.3 Use a 450t electroslag remelting furnace for upper recasting and forging, equipped with a φ2020 crystallizer and corresponding gas protection device.

[0075] 3.4 Place the dummy plate on top of the water-cooled bottom plate and place the conductive flux on it. The conductive flux consists of CaF2-TiO2.

[0076] Surround it with fluorite.

[0077] 3.5 Hang the graphite electrode on the frame. When the frame is lowered, the graphite electrode is required to support the conductive flux.

[0078] S4 electroslag remelting:

[0079] 4.1 The gas protection device starts with argon gas, with a flow rate of 300m 3 / h, time 20 minutes. Then turn 250m 3 / h.

[0080] 4.2 The slag is composed of fluorite-white corundum-limestone-fused magnesia-silicon dioxide-titanium dioxide.

[0081] 4.3 Electric slag making: Add fluorite - white corundum - limestone - fused magnesia - silicon dioxide - titanium dioxide in the order of addition until all components are melted.

[0082] 4.4Replace the graphite electrode with the consumable electrode.

[0083] 4.5 Turn on the power and gradually increase the power until the current reaches 20-35kA and the voltage reaches 120-150V. When the consumable electrodes are consumed, replace them with another set and continue smelting. During remelting, add aluminum every five minutes for deoxidation. Analyze slag samples every hour and adjust the amount of deoxidizer based on the results.

[0084] 4.6 When the distance from the target weight is 5-10t, gradually reduce the power and perform the feeding operation.

[0085] 4.7 When the target weight is reached, turn off the power, lift the consumable electrode, and turn off the argon gas.

[0086] S5 debonding:

[0087] Keep warm for 6 hours and then send to heat treatment furnace.

[0088] The method achieves that the Ti content of 100-ton grade 022Cr12Ni10MoTi steel after electroslag remelting meets the product requirements, and the specific value is: Ti: 0.13-0.15%, which meets the optimal performance requirement range of the product.

[0089] 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 them. 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 make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for controlling the Ti element content in electroslag remelting 100-ton grade 022Cr12Ni10MoTi steel, characterized in that: Adopt bipolar series electroslag remelting, and, The consumable electrode is produced by vacuum induction + vacuum consumable dual mode, and the Ti element in the consumable electrode is 0.10-0.17% (wt%); The filling ratio of consumable electrode and crystallizer is 0.3-0.35; The slag used for smelting is a hexavalent slag of fluorite-white corundum-limestone-fused magnesia-silicon dioxide-titanium dioxide.

2. The method for controlling the Ti element content in electroslag remelting 100-ton grade 022Cr12Ni10MoTi steel according to claim 1, characterized in that: Argon gas is used for protection throughout the electroslag remelting process, and the environment inside the electroslag remelting furnace is controlled to a reducing atmosphere by adding deoxidizers.

3. The method for controlling the Ti element content in electroslag remelting 100-ton grade 022Cr12Ni10MoTi steel according to claim 1 or 2, characterized in that: include: S1 designed consumable electrode: the Ti element in the consumable electrode is 0.10-0.17% (wt%); S2 production of consumable electrodes: using vacuum induction + vacuum consumable double production method; S3 smelting preparation: according to the size of consumable electrode, mold size and filling ratio, the consumable electrodes are matched and welded, and the weld is heated and kept warm after welding, with the holding temperature ≥ 200℃; CaF2-TiO2 conductive flux is used, and the conductive flux is surrounded by fluorite; S4 electroslag remelting: argon protection is used throughout the process, and the flow rate is 200-350m 3 / h; During the slag making process, the slag is added in the order of fluorite-white corundum-limestone-fused magnesia-silicon dioxide-titanium dioxide until all the components are melted; During the first consumption of the consumable electrode, gradually increase the power until the current reaches 20-35KA and the voltage reaches 120-150V; During remelting, Al is added every five minutes for deoxidation, and slag samples are analyzed every hour, and the amount of deoxidizer is adjusted based on the results; When the remaining distance from the target weight is less than the first threshold, the power is gradually reduced and the feeding operation is performed; When the target weight is reached, the power is turned off, the consumable electrode is raised, and the argon gas is turned off; S5 stripping: keep warm for 4-8 hours and then send to heat treatment furnace.

4. The method for controlling the Ti element content in electroslag remelting 100-ton grade 022Cr12Ni10MoTi steel according to claim 3, characterized in that: Before S3 pairing, the surface of the consumable electrode is also treated, and a protective coating is applied after the treatment. The protective coating is used to reduce the degree of surface oxidation of the consumable electrode after baking.

5. The method for controlling the Ti element content in electroslag remelting 100-ton grade 022Cr12Ni10MoTi steel according to claim 3, characterized in that: The paired consumable electrodes are welded using manual welding J507 electrodes.

6. The method for controlling the Ti element content in electroslag remelting 100-ton grade 022Cr12Ni10MoTi steel according to claim 3, characterized in that: In S4, the flow rate is 300-350m3 20-30min before the argon protection is turned on. 3 / h, then changed to 200-250m 3 / h.

7. The method for controlling the Ti element content in electroslag remelting 100-ton grade 022Cr12Ni10MoTi steel according to claim 3, characterized in that: In S4, the first threshold is 5-10t.

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