CN118371658A - Anode steel claw production method - Google Patents
Anode steel claw production method Download PDFInfo
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- CN118371658A CN118371658A CN202410547465.2A CN202410547465A CN118371658A CN 118371658 A CN118371658 A CN 118371658A CN 202410547465 A CN202410547465 A CN 202410547465A CN 118371658 A CN118371658 A CN 118371658A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 150
- 239000010959 steel Substances 0.000 title claims abstract description 150
- 210000000078 claw Anatomy 0.000 title claims abstract description 77
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 26
- 239000002893 slag Substances 0.000 claims abstract description 66
- 238000005266 casting Methods 0.000 claims abstract description 48
- 235000002245 Penicillium camembertii Nutrition 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 18
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 17
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- 238000010079 rubber tapping Methods 0.000 claims abstract description 15
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- 239000003795 chemical substances by application Substances 0.000 claims abstract description 6
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- 239000011572 manganese Substances 0.000 claims description 5
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- 239000007789 gas Substances 0.000 description 7
- 238000002844 melting Methods 0.000 description 7
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- 239000001301 oxygen Substances 0.000 description 3
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- 229910000851 Alloy steel Inorganic materials 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910001339 C alloy Inorganic materials 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
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- 229910000838 Al alloy Inorganic materials 0.000 description 1
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- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910005347 FeSi Inorganic materials 0.000 description 1
- 229910001309 Ferromolybdenum Inorganic materials 0.000 description 1
- 229910000592 Ferroniobium Inorganic materials 0.000 description 1
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- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
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- ZFGFKQDDQUAJQP-UHFFFAOYSA-N iron niobium Chemical compound [Fe].[Fe].[Nb] ZFGFKQDDQUAJQP-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention is applied to the casting industry, and discloses a production method of an anode steel claw, which comprises the following steps of 1) mixing steel slag when a molten steel component ≤0.1%C、0.5-1.5%Si、≤0.4%Mn、≤0.020%P、≤0.015%S、0.2-0.6%Cu、0.1-0.4%Ti、0.3-0.5%Mo、0.3-0.6%Cr、0.3-0.5%W、0.2-0.4%Nb;2） is smelted and tapping, placing FeTi particles at the bottom of a ladle, and blowing inert gas for 40 seconds to 1 minute after tapping; 3) The lost foam module is hollow; the lower jaw of the beam is provided with a heating riser, and the middle heating riser is jacked and injected; a chill is arranged below the beam, 4) a steel claw white mold is burnt before casting; slag avoiding pouring; firstly, pouring out a heat-preserving and heating agent, and poking out an agricultural film; 5) And (5) low-temperature annealing heat treatment. The invention obtains the internal high-compactness defect-free anode steel claw casting, the tensile strength is more than 400MPa at 400 ℃, the resistivity at the working temperature is reduced by about 30-40%, and the high acceptance of users is obtained.
Description
Technical Field
The invention is applied to the casting field, relates to an anode steel claw of an aluminum electrolysis cell, and in particular relates to a production method of the anode steel claw with low electrifying resistivity and high-temperature strength.
Background
The anode steel claw of the electrolytic aluminum is an important connecting component between a guide rod and a carbon block in the electrolytic tank, and the working temperature of the anode steel claw is about 300-500 ℃, which is the high temperature of the application. In addition, the anode steel claw is connected with the aluminum guide rod and clamps the anode carbon block, so the anode steel claw has the double functions of electric conduction and bearing, and is required to have better electric conduction, certain strength and dimensional stability, and especially under the condition of working temperature.
CN105624732a discloses a method for producing a low resistivity anode steel claw, which combines an aluminum core and steel. CN103603011B discloses an energy-saving and environment-friendly steel-aluminum alloy structural anode steel claw, after being treated by oxygen blowing technology, the contents of C and Si are reduced to 0.03-0.10%; melting by an aluminum steel heating aluminizing technology with the addition amount of aluminum being 2.5-4.0%; adding 0.3-0.5% rare earth silicon, and casting in steel mould. The voltage drop may be reduced by at least 30mV. The two patents described above use composite materials to reduce the resistivity.
CN117340548a discloses a production process of a low-resistivity high-performance anode steel claw, and the material adopts BTCY-1 hot rolled steel; the friction welding process is adopted, the welding fusion rate is more than or equal to 99 percent, and the resistivity is less than 11 mu omega mm at 20 ℃. CN117626137a discloses a low-resistivity energy-saving double-anode steel claw and a preparation method thereof, steel plates are reinforced by taking iron-carbon alloy as raw materials and adding 235B material, and impurity components of the iron-carbon alloy are controlled in the following ranges: c is less than or equal to 0.005%, mn is less than or equal to 0.10%, si is less than or equal to 0.01%, P is less than or equal to 0.003% and less than or equal to 0.005%, and S is less than or equal to 0.007%. Under the condition of ensuring that the overall resistivity of the steel claw is lower, the steel claw structure is ensured to have enough strength and rigidity. The two patents mentioned above use rolled steel and welding processes to manufacture the anode steel stud.
CN103639358B discloses a method for casting anode steel claw by lost foam and an anode steel claw white mould which is formed by the method, when the white mould is assembled, the claw leg white mould of the anode steel claw is placed downwards, then a connecting arm white mould is arranged on the claw leg white mould, a square table white mould is arranged on the connecting arm white mould again, and finally a riser is placed on the square table white mould. In this feeder system, the steel claw located farther from the feeder cannot be fed well to generate shrinkage cavity. For low-carbon steel castings, the lost foam casting process is easy to cause carburetion of the castings, and carburetion distribution is irregular.
Disclosure of Invention
The invention solves the technical problems that: the production method of the anode steel claw adopts lost foam casting, realizes low resistivity and high temperature and high strength, and meets the requirement of low energy consumption of electrolytic aluminum.
The technical scheme adopted by the invention is as follows: the anode steel claw production method comprises the following steps:
1) Smelting: the weight percentage of the molten steel is controlled to ≤0.1%C、0.5-1.5%Si、≤0.4%Mn、≤0.020%P、≤0.015%S、0.2-0.6%Cu、0.1-0.4%Ti、0.3-0.5%Mo、0.3-0.6%Cr、0.3-0.5%W、0.2-0.4%Nb, and the balance of Fe;
2) And (3) steel tapping and purifying: mixing molten steel and reducing slag, placing FeTi particles at the bottom of the ladle, and blowing inert gas into the ladle through a ladle bottom ventilation plug for stirring after tapping; the bottom blowing time is 40 seconds to 1 minute; the particle size of FeTi particles is 1.5-3mm;
3) And (3) lost foam modeling: the hollow and inner design of the module is provided with reinforcing ribs; during modeling, the claw heads of the anode steel claw are upwards, the cross beam is arranged downwards, each claw head is provided with a heating riser, and the middle heating riser is injected; a chilling block is arranged below the cross beam, and is in a mesh shape or is provided with a vent hole; the bottom drawing type molding sand box is adopted, so that the bottom of a casting is favorably cooled by air;
4) Pouring: firstly, quick casting and then slow casting; after casting, spreading a heat-preserving exothermic agent on the exothermic riser, and poking the agricultural film covered on the sand box; before casting, burning off the steel claw white mold by using a burning gun; slag avoiding pouring during pouring;
5) And (3) low-temperature annealing heat treatment: annealing temperature is 620-680 ℃ and annealing time is 6-8 hours.
Further, the step 1) adopts industrial pure iron and ferroalloy as charging materials, deoxidizing the reducing slag during smelting, and alloying the reducing slag after greening. The reducing slag material ratio is as follows: lime: bauxite: fluorite: siCa powder=1.2 to 1.5:1:0.5 to 1.2:0.3 to 0.5, wherein the SiCa powder is replaced by silicon-aluminum-barium-calcium-manganese or the SiCa powder and the SiCa powder are shared by the silicon-aluminum-barium-calcium-manganese.
Further, waste steel is adopted as the charging material in the step 1), oxidizing slag is produced for dephosphorization during smelting, and reducing slag is produced for desulfurization and deoxidation. The material ratio of the oxidizing slag is as follows: sponge iron accounting for 2-3% of the weight of the scrap steel, lime accounting for 1-3% of the weight of the scrap steel and fluorite accounting for 0.3-1% of the weight of the scrap steel. The reducing slag is prepared from the following materials in proportion: lime: bauxite: fluorite: siCa powder=1.2 to 1.5:1:0.2 to 0.5:0.1 to 0.3, wherein the SiCa powder is replaced by silicon-aluminum-barium-calcium-manganese or the SiCa powder and the SiCa powder are shared by the silicon-aluminum-barium-calcium-manganese. The sponge iron is replaced by rolling iron oxide scale, and the addition amount is 1-2.5% of the weight of the scrap steel.
The beneficial effects of the invention are as follows: the invention obtains the anode steel claw casting with high compactness and no defect, and has the advantages of low-power inspection, no looseness and shrinkage cavity and coarse grains. The inclusion test only included individual round small pieces, the size of which is much smaller than the grain size. The gas content reaches the level of refining the rolled steel. The tensile strength at 400 ℃ reaches more than 400 MPa. The resistivity in the working temperature range can be reduced by 30-40%, a huge electricity-saving effect is generated, and the high acceptance of users is obtained.
Drawings
FIG. 1 is an anode steel claw lost foam module;
FIG. 2 is a schematic view of an anode steel jaw riser (prior to placement of a vibratory sand mold in a flask).
Detailed Description
For anode steel claw castings, the factors influencing the conductivity and the high temperature strength of the anode steel claw castings are mainly as follows:
1. Component content. Pure iron has the smallest resistivity in ferroalloys, but its strength is also the smallest. C. The lower the content of the impurity element such as S, P, O, the lower the specific resistance. S, P, O is a main impurity element in cast steel, and formed sulfide, phosphide, oxide and other impurities have negative effects on strength and resistivity, so that the lower the control is, the better. C is a main element for improving the strength of cast steel, and carbide is utilized for improving the strength of cast steel. However, in pure iron, the presence of aluminum causes an increase in electrical resistance.
The application needs to meet the strength and dimensional stability of the service temperature while reducing the resistivity, and therefore, alloying elements such as solid solution strengthening or carbide strengthening elements which have little influence on the resistivity and can improve the strength of cast steel are required to be added into the cast steel. First, the order of arrangement of the degree of stability of carbide formation by the alloying elements from strong to weak is: ti, zr, V, nb, W, mo, cr, mn, fe. Secondly, the addition of Cu, mo, W, nb and other microalloying elements has little influence on the resistivity of the anode steel claw at the working temperature. In comprehensive consideration, the components of the anode steel claw are determined as follows ：≤0.1%C、0.5-1.5%Si、≤0.4%Mn、≤0.020%P、≤0.015%S、0.2-0.6%Cu、0.1-0.4%Ti、0.3-0.5%Mo、0.3-0.6%Cr、0.3-0.5%W、0.2-0.4%Nb.
In terms of resistivity, an increase in Cu content in the range of less than 0.6% of the alloy element has an effect of lowering the resistivity, but the slope of the straight line thereof is not large. The increase of Mo and W contents is not obvious, and the slope of a straight line for increasing the resistivity is small. The resistivity of Ti, cr and Nb is increased, but the increasing amplitude is far lower than that of Al element, and the slope of the increasing straight line of the resistivity is less than half of that of the Al element. From the viewpoint of the effect on the resistivity, the content of Ti, cr, nb is preferably controlled to be lower than the lower limit as the content of C is lower.
The low high temperature strength of carbon steel is usually due to diffusion of interstitial solid solution solute atoms and dislocation climb hand-over slip. The diffusion rate of substitutional atoms is generally several orders of magnitude lower than that of solute atoms, and the high-temperature strength of alloy steel can be increased by utilizing the strong chemical interaction between substitutional solid solution atoms and interstitial solid solution atoms. Si, W, mo, nb, cr, etc. can play this role, improving the high temperature strength.
From the viewpoint of structure, C, cu, and Mn are austenite forming elements, and the addition amount is not necessarily high in order to obtain a single ferrite. Ti, si, mo, W is ferrite forming element, and substitution solid solution strengthening is generated, the addition amount of the ferrite forming element can be properly increased, and the performance of the anode steel claw can be met due to the relatively high price of Mo and W. Si and Cu are non-carbide elements, are used for ferrite solid solution strengthening, and Si is a main element for deoxidizing molten steel. Ti, nb, W, mo, cr is a strong carbide forming element, so that stable carbide is formed, unstable iron carbide is avoided, and the content of solid solution carbon in Fe is reduced, so that a single ferrite structure matrix is obtained.
In summary, the application has the following design concept: 1) When smelting, the C, S, P, O content is reduced, and the method is maximally close to industrial pure iron, so as to reduce the resistivity. 2) The high-temperature strength is increased by utilizing an alloying mode, firstly, the ferrite is subjected to solid solution replacement and reinforcement, and secondly, the carbide is stabilized and reinforced, so that the tissue stability and the dimensional stability are maintained. 3) The multi-element alloy is adopted for alloying, the total content of alloy elements is low although the alloy elements are more, the strength is increased, and meanwhile, the negative influence on the resistivity is small, so that the ideal performance of the anode steel claw is obtained.
2. Casting defects. Such as shrinkage cavity, porosity, inclusions, etc., the more and greater the casting defects, the higher the resistivity of the anode steel jaw, and also is a crack generating source, which is unfavorable for high temperature strength. Therefore, during production, dense castings need to be cast.
3. Organization. The resistivity of the ferrite structure is lower than that of pearlite, and the anode steel claw is suitable to obtain a single ferrite structure. Moreover, the ferrite is also higher in structural stability than pearlite, and in the range of the anode steel jaw operating temperature, ferrite is substantially free from transformation, but pearlite is free from transformation due to diffusion of solute atoms, such as transformation into ferrite and carbide. Therefore, the dimensional stability and the performance stability of pearlite are inferior to those of ferrite.
4. Grain boundaries or grain sizes. The larger the grain size, the smaller the grain size, and the more grain boundaries, the more favorable the improvement of the comprehensive performance at room temperature. But the grain boundaries increase and the resistivity increases. To obtain a lower resistivity, it is desirable to obtain a single crystal structure, i.e., larger matrix grains. In terms of structural stability, solute atoms diffuse and have more grain boundaries in the working temperature of the anode steel claw, so that energy fluctuation of grains is increased, the diffusion of the solute atoms is easy to form grain combination, and the phenomena of poor dimensional stability, abrupt change of high-temperature performance and the like are caused.
In order to obtain the ideal anode steel claw casting, namely the low-carbon, low-sulfur, low-phosphorus, low-oxygen and multi-element microalloying material; compact castings; a single ferrite structure; coarse grains, etc.; in each production process of casting, strict control is required.
Example 1
1) Smelting. The smelting furnace for casting mainly adopts a medium-frequency electric furnace, and the charging material is low-carbon high-quality scrap steel.
And (3) oxidizing slag production: after the scrap steel is melted, sponge iron accounting for 2-3 percent of the weight of the scrap steel, lime accounting for 1-3 percent and fluorite accounting for 0.3-1 percent are added at the temperature of about 1520-1550 ℃ under the condition that the superheat degree is not high, so that the dephosphorization and the carbon reduction of the oxidation slag are realized. The sponge iron contains a large amount of iron oxide which is the main component for forming oxide slag, and lime provides alkaline environment for dephosphorization, so that three conditions of low temperature, oxidation and alkaline dephosphorization are realized. The sponge iron can also be replaced by rolling iron scale, and the addition amount of the sponge iron is 1-2.5% of the weight of the scrap steel when the iron scale is adopted. In the process of melting the oxidizing slag, the slag is stirred, so that the interface reaction of the steel slag is increased. And (3) after the oxidizing slag is melted and stirred for 10-20min, a slag conglomeration agent is scattered, and the intermediate frequency furnace is tipped over for a certain angle to remove slag. Slag aggregation agent is scattered in for multiple times, and the color difference between slag and molten steel is noticed during slag skimming, so that molten steel is prevented from being scraped out. The oxidizing slag must be cleaned off to prevent the phosphorus from being recovered in the reduction stage.
Reducing slag is produced: after the oxidizing slag is scraped clean, lime, bauxite, fluorite, deoxidizer and the like are added into the furnace to make reducing slag for desulfurization and deoxidization. Lime is used for improving the alkalinity of the reducing slag, bauxite is used for reducing the melting point of lime, and fluorite has a low melting point and plays a role in fluxing. Fluorite is melted, so that the combination between lime and bauxite is promoted, and the melting point of reducing slag is reduced. When the materials are added, siCa powder, feSi powder, aluminum wire or silicon aluminum barium calcium manganese composite deoxidizer is added, caO generated by Ca oxidation is used for improving the alkalinity of the reducing slag, and SiO 2 produced by Si oxidation is used for forming SiO 2 -Al2O3 -CaO low-melting-point ternary system reducing slag so as to promote the interface reaction of steel slag. The SiCa powder or the Si-Al-Ba-Ca-Mn composite deoxidizer is used as a reducing agent, and the FeSi powder and the aluminum wire are only used as auxiliary reducing agents and are not used as main reducing agents. The temperature of the molten steel subjected to deoxidization and desulfurization is not lower than 1600 ℃, and three conditions of high temperature, alkalinity and deoxidization and desulfurization are satisfied. The reducing slag material ratio is lime: bauxite: fluorite: siCa powder (or sial-ba-ca-mn) =1.2 to 1.5:1:0.2 to 0.5:0.1 to 0.3 percent, and the total amount of the reducing slag materials is 2 to 5 percent of the weight of the molten steel. In the slag making and reducing process of the reducing slag, the reducing slag is stirred to promote smelting, so that molten steel is not exposed to the limit. Electromagnetic stirring of molten steel promotes interfacial desulfurization and deoxidation reaction of the reducing slag. The CaO content in the lime is not less than 85 percent, the Al 2O3 content in bauxite is not less than 80 percent, and fluorite is more than two stages.
Alloying: after the reducing slag turns green, adding low-sulfur-phosphorus content or industrial pure alloy to make alloying, and regulating molten steel components, such as brass, metal chromium, molybdenum bar and tungsten bar, or low-sulfur-phosphorus content ferromolybdenum, ferrotungsten, ferroniobium and ferrosilicon. The low sulfur and phosphorus content refers to that P is less than or equal to 0.035 percent and S is less than or equal to 0.04 percent in the alloy, and the influence on sulfur and phosphorus of molten steel is not great because the addition amount of the alloy is not great. From the viewpoint of production economy, the use of an industrially pure alloy is an indispensable measure for P to the upper limit in molten steel.
2) And (5) tapping and purifying. After the smelting components of the intermediate frequency furnace are qualified, rapidly heating to 1680 ℃ and tapping, pouring molten steel and reducing slag into a pouring ladle at the same time, realizing steel slag mixing, and increasing steel slag interface reduction reaction in the tapping process.
Before tapping, the baked FeTi particles with the granularity of 1.5-3mm are placed at the bottom of the pouring ladle, ti is easy to oxidize, and is added into an intermediate frequency furnace for alloying, and the Ti is easy to react with oxygen in the air to be damaged during tapping. The pouring ladle bottom is added, so that the use can be maximally realized. Meanwhile, feTi can be used as a reducing agent to play a role in deoxidization. And after tapping, argon or nitrogen inert gas is immediately introduced into the ladle through a ladle bottom ventilation plug, and molten steel is stirred. And stirring the molten steel by using inert gas in the standing time of the molten steel, fully contacting inclusions in the molten steel with the reducing slag on the surface of the molten steel, and adhering the inclusions with the reducing slag, so that the molten steel is purified, and the pressure of the bottom blowing inert gas is limited by that the molten steel does not expose the reducing slag. After the molten steel is kept stand, inert gas is closed, reducing slag in the pouring ladle is scraped off, and covering slag is scattered to cover the liquid surface of the molten steel. In the stirring process of blowing inert gas into molten steel, bubbles are favorable for adsorbing gas in the molten steel, and part of gas in the molten steel is carried out from the molten steel, so that the gas content of [ O ] [ N ] [ H ] and the like in the molten steel is reduced. The bottom blowing time is about 40 seconds-1 minute, the tapping temperature is high, the upper limit can be set, the tapping temperature is low, and the lower limit can be set, so that the casting temperature is controlled. And (5) covering the covering slag and then quickly lifting the covering slag to a pouring station. The purification treatment of the molten steel is beneficial to improving the purity of the alloy steel, and the purpose of reducing the resistivity is achieved.
3) And (5) lost foam modeling.
And (3) module design: the produced anode steel claw is three-claw type, the beam size is 100 multiplied by 150 multiplied by 980mm (width multiplied by height multiplied by length), the steel claw size phi is 180 multiplied by 250mm (diameter multiplied by height), and the center distance between adjacent steel claw cylinders is 400mm. The figure 1 is a casting machine-made white mold, two pieces are separated from the middle to form an anode steel claw module, the whole module is hollow, so that the gas generation amount of the white mold in pouring and the carbon defect of the casting are reduced, and the reinforcing ribs are designed to control the deformation of the cylindrical white mold.
Casting head design: the lacing wire is designed between the steel claw cylinders to prevent the casting from shrinking and deforming, and the lacing wire is used as an auxiliary inner pouring gate. During modeling, the claw heads of the anode steel claw are upward, the cross beam is downward, and a cylindrical exothermic riser with diameter of 200 mm multiplied by 300mm (diameter multiplied by height) is arranged on each claw head, as shown in figure 2. And during casting, the steel is directly cast from the middle exothermic riser, and one piece is cast.
And (3) modeling design: 1) And (3) cooling iron. A50 mm-thick chill is arranged below the cross beam, and is in a mesh shape or is provided with a vent hole. In order to prevent the chill from sinking in the molding vibration process, the chill is preferably temporarily fixed on the inner wall of the sand box. The distance between the top surface of the chiller and the lower surface of the cross beam is not more than 30mm. The chill absorbs heat in two ways, namely conduction is carried out, the chill can absorb heat transferred by dry sand, convection is carried out, air flow in the negative pressure vacuum sand box promotes convection heat transfer, and the mesh-shaped chill or vent holes can avoid obstruction of air flow. The action of the chill enables the anode steel claw to form a temperature gradient from bottom to top, the cross beam is fed by the steel claw, and the steel claw is fed by the exothermic riser, so that a compact casting without looseness and shrinkage cavity is formed. 2) The white mold is pre-burned. Three steel claw white molds were burned off one by one with a burning gun, the structure of which applicant has disclosed in CN107470561 a. In order to prevent sand from collapsing due to vacuum degree damage, when one steel claw white mold is burnt, the other two steel claws are covered and sealed on the exothermic riser, and only the middle exothermic riser is opened before casting. Meanwhile, the thickness of the coating on the outer surface of the steel claw white mold is preferably controlled at the upper limit of the process thickness, firstly, the air permeability of the coating can be reduced, the collapse is prevented, secondly, the heat preservation effect can be improved, and the feeding of molten steel is enhanced. The pre-burning of the white mold is consistent with the hollow theory of the white mold, so that adverse effects of gasification of the white mold on molten steel during pouring are avoided, and defects such as carburetion, air holes, inclusion and the like of the molten steel are prevented.
It should be noted that the white mold pre-combustion measure depends on the thickness of the module. If the hollow size of the module is large, the thickness of the white mold is small, the volume is small, the adverse effect on molten steel is ignored, and the white mold pre-combustion measure can be omitted. If the deformation of the module is considered, the thickness of the white mold is large, and a white mold pre-combustion measure is adopted.
4) Pouring.
And the purified molten steel is lifted to a pouring station, and is rapidly poured by using a large-size pouring cup, so that the phenomenon that the molten steel is wrapped by air caused by vacuum suction of outside air is avoided. And the casting is slowly performed in the later stage, so that molten steel is prevented from overflowing from a self-heating riser, molten steel is wasted, and meanwhile, the phenomenon that an agricultural film covering a sand box and keeping vacuum is burnt out at high temperature is avoided. And after casting, taking the sealing covers away, and scattering heat-insulating exothermic agent and heat-insulating riser molten steel on the three exothermic risers.
After the molten steel is poured, a plurality of holes are poked into the agricultural film covered by the sand box, and the positions of the holes are away from the heating riser. The bottom vacuumizing type sand box is not suitable for the way of vacuumizing the peripheral wall of the sand box. The pumped air can avoid the positions of the riser and the steel claw, cool the bottom of the casting, and achieve the purposes of promoting the air flow between sand grains of the sand box and accelerating the cooling of the casting. Therefore, on the premise of keeping the casting without expanding the box, the temperature difference between molten steel and sand grains can be kept to the maximum extent, and the sequential cooling of the molten steel is enhanced. The superheat degree exists at the solidification front of the molten steel, which is favorable for the growth of columnar crystals, thereby being favorable for forming large-size columnar crystals and reducing the resistivity. The number and the size of the holes are based on the principle that the vacuum degree of the sand box is not seriously reduced, so that the case expansion caused by insufficient sand strength is avoided.
The air flowing in the flask cools not only the bottom sand but also the chill as it passes through the mesh or vent holes of the chill. Mesh or air vent on the chill ensures that air is guided to flow from the bottom of the casting, and plays a role in cooling the bottom of the casting.
The tea kettle bag is preferably used for pouring, or the refractory asbestos is used for blocking slag at the mouth of the pouring bag, and a slag avoiding pouring mode is adopted to prevent slag on the liquid surface of molten steel from flowing into the casting.
5) And (5) cleaning castings.
After the casting is unpacked, the riser is cut off, and the lacing wire and the furnace test block are fed into the furnace together with the casting for heat treatment to be used as a detection sample block.
6) And (5) heat treatment.
And (5) after cleaning the anode steel claw, feeding the anode steel claw into a heat treatment furnace, and carrying out low-temperature annealing treatment. The annealing temperature is 620-680 ℃, lower than the austenite transformation temperature and higher than the using temperature. The annealing time is 6-8 hours, so as to promote the diffusion of elements, avoid the large change of performance or dimensional change caused by the diffusion of elements in the use process, and strengthen the relative stability of the performance and the dimension. And discharging the material from the furnace for air cooling after annealing.
Example 2
In the embodiment, the melting furnace burden adopts a furnace return burden and industrial pure iron. Because C, P, S content in the furnace returns and industrial pure iron is low, the oxidation process of dephosphorization and carbon reduction is not needed. The purpose of reducing slag production is to deoxidize only, without strengthening desulfurization. Namely, the alkalinity of the reducing slag is not emphasized, fluorite is mainly utilized to reduce the melting point of the reducing slag, and the material ratio of the reducing slag is as follows: lime: bauxite: fluorite: siCa powder (or sial-ba-ca-mn) =1.2 to 1.5:1:0.5 to 1.2:0.3 to 0.5. Because of the low sulfur and phosphorus content in the molten steel, the low sulfur and phosphorus content ferroalloy can be used for alloying, and the expensive industrial pure alloy is not used.
Compared with the embodiment 1, the embodiment adopts the proportion mode of the furnace returning material, the industrial pure iron and the ferroalloy as the charging material, the charging material cost is relatively low, the production rhythm is fast (no oxidation dephosphorization process and no reinforced desulfurization) and the erosion of the oxidizing slag to the furnace lining is not generated, and the furnace life is prolonged, so the embodiment has relatively low comprehensive production cost.
The procedures of tapping, lost foam molding, pouring, casting cleaning, heat treatment and the like are the same as in example 1.
The invention is adopted to obtain the internal high-compactness and defect-free anode steel claw casting, and the key inspection results are as follows:
1) The components are as follows. Taken from the box-associated test block, P:0.013-0.017%, S:0.009-0.012%.
2) Low power. Sawing from the middle of the cylindrical steel claw, polishing the section, corroding with low-concentration acid, and performing low-power inspection, wherein no loosening and shrinkage cavity are found, and the grains are coarse.
3) And (5) inclusion. The sample from the outer surface of the cylindrical steel claw is sampled and inspected for inclusions, a plurality of test blocks are not found, and only individual round small blocks are included, and the size is far smaller than the grain size.
4) And (3) gas. The steel is obtained from lacing wires, and gas analysis is carried out by an external commission, wherein the contents of [ O ], [ N ], [ H ] are 19ppm, 110ppm and 1.3ppm respectively, and the gas content reaches the level of refining the rolled steel.
5) High temperature tensile properties. Self-checking, namely taking out from the lacing wire, wherein the tensile strength at 400 ℃ reaches more than 400MPa, and the yield strength reaches more than 250 MPa.
6) Resistivity. The resistivity is compared with the existing anode steel claw by a user, and the resistivity in the working temperature range can be reduced by about 30-40%, so that a huge electricity-saving effect is generated.
The anode steel claw product produced by the invention obtains the high approval of the user, the applicant is listed in a qualified purchasing party list of the user, and a purchasing plan is added.
Claims (10)
1. The production method of the anode steel claw comprises the following steps:
1) Smelting: the weight percentage of the molten steel is controlled to ≤0.1%C、0.5-1.5%Si、≤0.4%Mn、≤0.020%P、≤0.015%S、0.2-0.6%Cu、0.1-0.4%Ti、0.3-0.5%Mo、0.3-0.6%Cr、0.3-0.5%W、0.2-0.4%Nb, and the balance of Fe;
2) And (3) steel tapping and purifying: mixing molten steel and reducing slag, placing FeTi particles at the bottom of the ladle, and blowing inert gas into the ladle through a ladle bottom ventilation plug for stirring after tapping;
3) And (3) lost foam modeling: the hollow and inner design of the module is provided with reinforcing ribs; during modeling, the claw heads of the anode steel claw are upwards, the cross beam is arranged downwards, each claw head is provided with a heating riser, and the middle heating riser is injected; a chill is arranged below the cross beam;
4) Pouring: firstly, quick casting and then slow casting; after casting, spreading a heat-preserving exothermic agent on the exothermic riser, and poking the agricultural film covered on the sand box;
5) Annealing heat treatment: annealing temperature is 620-680 ℃ and annealing time is 6-8 hours.
2. The method for producing anode steel claw according to claim 1, wherein: before pouring, the steel claw white mold is burnt by a burning gun; slag is avoided during casting.
3. The method for producing anode steel claw according to claim 1, wherein: in the step 3), the chill is mesh-shaped or a vent hole is processed on the chill.
4. The method for producing anode steel claw according to claim 1, wherein: in the step 3), the molding sand box adopts a bottom drawing type.
5. The method for producing anode steel claw according to claim 1, wherein: the bottom blowing time of the step 2) is 40 seconds to 1 minute; the particle size of FeTi particles is 1.5-3mm.
6. The method for producing anode steel claw according to claim 1, wherein: the step 1) adopts industrial pure iron and ferroalloy as charging materials, deoxidizes reducing slag, and then alloys the reducing slag after green.
7. The method for producing anode steel claw according to claim 6, wherein: the material ratio of the reducing slag is as follows: lime: bauxite: fluorite: siCa powder=1.2 to 1.5:1:0.5 to 1.2:0.3 to 0.5, wherein the SiCa powder is replaced by silicon-aluminum-barium-calcium-manganese or the SiCa powder and the SiCa powder are shared by the silicon-aluminum-barium-calcium-manganese.
8. The method for producing anode steel claw according to claim 1, wherein: the step 1) adopts scrap steel as charging material, and the charging material is subjected to dephosphorization and deoxidization of oxidizing slag and reducing slag.
9. The method for producing anode steel claw according to claim 8, wherein: the material ratio of the oxidizing slag is as follows: sponge iron accounting for 2-3% of the weight of the scrap steel, lime accounting for 1-3% of the weight of the scrap steel and fluorite accounting for 0.3-1% of the weight of the scrap steel; the sponge iron is replaced by rolling iron oxide scale, and the addition amount is 1-2.5% of the weight of the scrap steel.
10. The method for producing anode steel claw according to claim 8, wherein: the material ratio of the reducing slag is as follows: lime: bauxite: fluorite: siCa powder=1.2 to 1.5:1:0.2 to 0.5:0.1 to 0.3, wherein the SiCa powder is replaced by silicon-aluminum-barium-calcium-manganese or the SiCa powder and the SiCa powder are shared by the silicon-aluminum-barium-calcium-manganese.
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