CN113523205A - Novel spheroidizing inoculation treatment method - Google Patents
Novel spheroidizing inoculation treatment method Download PDFInfo
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- CN113523205A CN113523205A CN202110764080.8A CN202110764080A CN113523205A CN 113523205 A CN113523205 A CN 113523205A CN 202110764080 A CN202110764080 A CN 202110764080A CN 113523205 A CN113523205 A CN 113523205A
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- inoculant
- spheroidizing
- ladle
- molten iron
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/10—Making spheroidal graphite cast-iron
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/10—Making spheroidal graphite cast-iron
- C21C1/105—Nodularising additive agents
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/08—Making cast-iron alloys
- C22C33/10—Making cast-iron alloys including procedures for adding magnesium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/04—Cast-iron alloys containing spheroidal graphite
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/10—Cast-iron alloys containing aluminium or silicon
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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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
Abstract
The invention discloses a novel spheroidizing inoculation method, which comprises the steps of selecting two foundry ladles as a transfer ladle and a spheroidizing ladle respectively; after the components of the molten iron in the furnace are qualified, overheating to 1480-1500 ℃, discharging the molten iron to a transfer ladle, pouring out the required weight, and adding a primary inoculant into the transfer ladle; a nodulizer and a secondary inoculant are preset in the nodulizing ladle; transporting the transfer ladle and the spheroidizing ladle to a pouring site, hoisting the transfer ladle to measure weight and measure temperature, rapidly pouring molten iron into the spheroidizing ladle at 1400-1460 ℃, and adding a tertiary inoculant into the spheroidizing ladle while pouring the molten iron; during pouring, adding a fourth-time inoculant along molten iron along with flow; the method adopts the treatment process of ladle-to-ladle spheroidizing inoculation, reasonably controls the addition amount of the inoculant at each time, obviously improves the inoculation treatment effect, ensures that the spheroidizing effect is more ideal, has more graphite, good graphite form and stable mechanical property and metallographic structure, and can finally stably produce the qualified large-scale nodular iron casting.
Description
Technical Field
The invention relates to the technical field of casting, in particular to a novel spheroidizing inoculation method.
Background
Abnormal graphite such as flowering, broken block and thick graphite easily appear in the heavy and large section nodular cast iron casting, and spheroidization recession and inoculation recession phenomena can be generated due to long liquid cooling and solidification time, which can affect the matrix structure and seriously deteriorate the mechanical property of the casting.
At present, when large-scale ductile iron parts are produced, a traditional flushing-in spheroidizing process is generally adopted, namely, a spheroidizing agent and an inoculant are added at the bottom of a spheroidizing ladle, and a secondary stream-following process is added during pouring to produce the large-scale ductile iron parts.
For example, in 2016, a method for preparing a nodular cast iron alloy is disclosed in Chinese patent publication No. CN103805731B, and the method comprises ladle inoculation, ladle inoculation and stream inoculation. In the invention, a ladle-to-ladle inoculation process is added between the original two steps of inoculation in a spheroidized ladle and stream inoculation, so that a special process of instantaneous multi-time inoculation is realized; however, the mode of ladle inoculation is more suitable for the production of small nodular iron castings, and the mode has no obvious effect on the production of large and large-tonnage nodular iron castings.
Disclosure of Invention
The invention aims to provide a novel spheroidizing inoculation method aiming at the problems in the prior art, and the molten iron before spheroidizing is optimized so as to provide a good spheroidizing platform, meanwhile, the temperature required by spheroidizing is stably controlled, the times in the spheroidizing inoculation process are increased, the quantity and the form of graphite after spheroidizing are greatly improved, stable mechanical property and metallographic structure are obtained, and finally, the qualified large-scale ductile iron parts are stably produced.
In order to achieve the purpose, the invention adopts the technical scheme that:
a novel spheroidizing inoculation method comprises the following operation steps:
(1) selecting two foundry ladles, one as a transfer ladle and the other as a spheroidizing ladle;
(2) after the components of the molten iron in the furnace are qualified, overheating to 1480-1500 ℃, discharging the molten iron to the transfer ladle, pouring out the required weight, and adding a primary inoculant into the transfer ladle, wherein the adding amount is 0.1-0.3%;
(3) a nodulizer and a secondary inoculant are preset in the nodulizing ladle, the addition amount of the nodulizer is 1.0-1.4%, the addition amount of the secondary inoculant is 0.3-0.6%, the secondary inoculant covers the nodulizer, and a covering layer is arranged on the secondary inoculant;
(4) transporting the transfer ladle and the spheroidizing ladle to a pouring site, hoisting the transfer ladle to measure weight and measure temperature, quickly pouring molten iron into the spheroidizing ladle at 1400-1460 ℃, and adding a tertiary inoculant into the spheroidizing ladle while pouring the molten iron, wherein the addition amount of the tertiary inoculant is 0.2-0.5%;
(5) during pouring, four-time inoculant is added along with the molten iron, and the adding amount of the four-time inoculant is 0.05-0.15%. The addition of the inoculant is calculated according to the percentage of the total pouring amount.
The spheroidizing inoculation method adopts the ladle-to-ladle spheroidizing inoculation treatment process, adopts multiple inoculation treatments in the processes of tapping, ladle-to-ladle and pouring, reasonably controls the addition amount of the inoculant at each time, obviously improves the inoculation effect, ensures that the spheroidizing effect is more ideal, has a large amount of graphite, good graphite form and stable mechanical property and metallographic structure, and can finally stably produce the qualified large-scale nodular iron casting.
The spheroidizing inoculation method obtains unexpected effects by adding the inoculant four times backwards, is not brought by simple frequency increase, has close relation with the adding time and the adding amount of the inoculant, has long waiting time of tapping molten iron and long solidification time of castings due to large wall thickness and heavy tonnage of thick and large section nodular cast iron, and can carry out spheroidizing inoculation on different time nodes and pipe fitting procedures by adding the inoculant in a fractional amount; the primary inoculant is added into the transfer ladle along with molten iron during tapping, the transfer ladle can be transferred to a balling ladle after waiting for a period of time, and the inoculant reacts in the transfer ladle to play a role of pre-adjustment in the process; a part of molten iron is directly discharged into the spheroidizing ladle, and since the secondary inoculant and the nodulizer are preset in the spheroidizing ladle, the molten iron starts to be spheroidized under the action of the secondary inoculant and the nodulizer after entering, and the process is just continued until the spheroidizing ladle is transported to a pouring site; in the casting site, the pretreated molten iron in the transfer ladle is poured into the spheroidizing ladle again for mixing, and the inoculant is added for three times along with the flow, so that the phenomena that the inoculant added in the initial stage is influenced by high temperature and decays for a long time are avoided, and the spheroidizing effect is better under the condition that the total addition amount of the inoculant and the addition amount of the spheroidizing agent are not increased; finally, the inoculant is added along with the molten iron flow for four times during the pouring of the molten iron, so that the spheroidization effect can be further strengthened, and the phenomenon of spheroidization recession of the molten iron in the long-term solidification process is less.
By adopting the spheroidizing inoculation method, the produced nodular cast has good quality stability, the spheroidization grade of the cast for repeated production and batch production activities is above grade 3, the graphite grade is not less than grade 5, and the volume fraction of ferrite is not less than 98%.
Further, the primary inoculant in the transfer ladle is poured into the transfer ladle from the bottom of the primary inoculant, and the primary inoculant is a Ba-containing inoculant with the granularity of 5-15 mm. The Ba-containing inoculant can promote graphitization, reduce chilling tendency, improve graphite morphology and distribution, increase eutectic cluster quantity, refine matrix structure, and maintain good effect for a period of time after inoculation treatment, which is enough for linking next inoculation.
Further, a dam is arranged at the bottom of the spheroidizing bag, which is far away from the sprue, the spheroidizing agent is filled in a region enclosed by the dam and the inner wall of the spheroidizing bag, the secondary inoculant is filled on the surface of the spheroidizing agent after the spheroidizing bag is compacted and flattened, a thin steel plate is covered on the surface of the secondary inoculant to be used as the covering layer after the spheroidizing bag is compacted and flattened, and a covering agent is also arranged between the thin steel plate and the secondary inoculant; the secondary inoculant is also a Ba-containing inoculant with granularity of 5-15 mm.
The enclosing of the dam and the covering of the thin steel plate are adopted, so that the phenomenon of poor inoculation and spheroidization caused by instantly dispersing the nodulizer and the inoculant when molten iron is added can be avoided, and the inoculant and the nodulizer are dispersed and reacted in the molten iron after a certain amount of molten iron is filled, so that the spheroidization inoculation effect is improved.
Further, the tertiary inoculant is added from one side of the spheroidized ladle along with the flow of molten iron in the ladle pouring process, and the tertiary inoculant is also a Ba-containing inoculant with the granularity of 5-15 mm.
Further, the fourth-time inoculant is added from the upper part of the spheroidizing bag through a stream inoculation device, and the fourth-time inoculant is a Bi-containing inoculant with the granularity of 0.5-1.5 mm. The fine-particle Bi-containing inoculant is suitable for being added along with stream inoculation, and is beneficial to accurate control of inoculation amount.
Furthermore, the nodulizer is a heavy RE nodulizer, the main chemical components of which are 5-8 Mg, 1.0-2.0 RE, 1.5-2.5 Ca, 42-45 Si, a small amount of Ba (such as 1.8-2.5), a trace amount of Bi and Sb (such as less than 0.1) and the balance of Fe, and the nodulizer can be a commercially available product according to wB (%).
Further, the chemical components of the primary inoculant, the secondary inoculant and the tertiary inoculant are all arranged as follows: 1-3 of Ca, 4-6 of Ba, 67-72 of Si, trace Bi and Sb (0.1-1) and the balance of Fe, all calculated according to wB (%), do not contain REO, and can select commercial products such as nodulizer and inoculant produced by Longnan Longyu heavy rare earth science and technology Limited company.
Further, the chemical components of the four-time inoculant are as follows: a small amount of REO (less than 1), 2-3 Ca, 3-5 Ba, 55-65 Si, a small amount of Bi and Sb (less than 1), and the balance Fe, all in terms of wB (%).
Further, 40-60% of low-Mn stamping scrap steel and 60-40% of Q10 pig iron are selected to be melted and smelted, 93% of carburant with carbon content is selected to be added in the furnace along with the scrap steel in the early stage, FeSi is adopted to adjust the original Si content in the furnace, and the qualified components of the original molten iron after smelting are as follows:
C. 3.9-4.1% of Si, 0.9-1.2% of Mn, less than 0.3% of S, less than 0.025% of P, and the balance of Fe;
the components of the nodular cast iron casting obtained after the spheroidizing inoculation treatment are as follows: w (C) 3.5-3.9%, w (Si) 2.0-2.7%, w (Mn) less than 0.3%, w (P) less than 0.04%, w (S) less than 0.025%, w (Mg) 0.04-0.06%, and the balance Fe.
That is, after the spheroidizing inoculation treatment, the obtained casting not only has great improvement on the spheroidization grade and the graphite grade, but also has the advantages of improving C, Si content, having lower residual magnesium content and improving the mechanical property of the nodular casting.
Further, the stream inoculation device comprises a stream following funnel and two connecting rods for fixedly supporting the stream following funnel, wherein the two connecting rods are symmetrically arranged on the periphery of the stream following funnel, and the connecting rods are arranged in parallel to a cross beam above a suspension arm of the spheroidizing bag; a vertical slide way is arranged on the outer side of the suspension arm, a slide block is arranged on the slide way, an electric push rod is arranged on the slide block, and the output end of the electric push rod is connected with the end part of the connecting rod; the outlet of the lower end of the flow following funnel is provided with a plug, the plug is connected with a pull rope, the surfaces of the flow following funnel and the connecting rod are respectively provided with a wiring groove, and the pull rope is led to the outside of the balling ladle along the wiring grooves.
The position of the stream following funnel can be flexibly adjusted through the arrangement of the stream following inoculation device, and the stream following funnel can also move in the inclined pouring process of the spheroidizing ladle, so that the added four-time inoculant can better flow into a cavity along with the molten iron flow, the adding position can be controlled more reasonably, and the problem of inconsistent adding caused by the unchanged adding position due to the inclined spheroidizing ladle is avoided; and the safety is higher after setting up like this, can remote control, has avoided the workman to be close to closely to the ladle.
The inoculant for stream inoculation can be arranged in the stream following funnel in advance, and the transfer of molten iron in the ladle pouring process is not influenced by controlling the high-low internal and external positions of the stream following funnel.
When the device is used, the sliding block is controlled by the motor to move up and down along the slide way, and the electric push rod, the connecting rod and the following leakage hopper are lifted and descended together; the connecting rods can be driven to move inwards or outwards at the same time by controlling the electric push rod, so that the horizontal position of the following funnel is adjusted.
The sliding block and the electric push rod are arranged on the outer side of the suspension arm, so that the electric control components can be prevented from being directly baked at high temperature. The arrangement of the wiring groove is convenient for the regular leading-out of the pull rope.
Compared with the prior art, the invention has the beneficial effects that: 1. the spheroidizing inoculation method adopts the ladle-to-ladle spheroidizing inoculation treatment process, adopts multiple inoculation treatments in the processes of tapping, ladle-to-ladle and pouring, reasonably controls the addition amount of an inoculant at each time, obviously improves the inoculation effect, ensures that the spheroidizing effect is more ideal, has a large amount of graphite, good graphite form and stable mechanical property and metallographic structure, and can finally stably produce qualified large-scale nodular iron castings; 2. by adopting the spheroidizing inoculation method, the produced nodular cast has good quality stability, the spheroidization grade of the cast for repeated production and batch production activities is above grade 3, the graphite grade is not less than grade 5, and the volume fraction of ferrite is not less than 98%; 3. after the spheroidizing inoculation treatment, the obtained casting is greatly improved in spheroidizing grade and graphite grade, the C, Si content is improved, and the mechanical property of the nodular casting is also improved; 4. the position of the stream following funnel can be flexibly adjusted through the arrangement of the stream following inoculation device, the stream following funnel can also move in the inclined pouring process of the spheroidizing ladle, so that the added inoculant can better flow into a cavity along with the molten iron flow, the adding position can be controlled more reasonably, and the spheroidizing inoculation effect can be improved; and after the device is arranged, the safety is higher, and the device can be controlled remotely.
Drawings
FIG. 1 is a schematic illustration of a ladle to ladle process for a novel spheroidizing inoculation process of the present invention;
FIG. 2 is a metallographic structure of a 40mm cast-on test block of a lower shell obtained by the spheroidizing inoculation method of the present invention;
FIG. 3 is a metallographic structure of a 70mm cast test block of a lower shell obtained by the spheroidizing inoculation method of the present invention;
FIG. 4 is a schematic front view of a stream inoculation apparatus of the present invention;
FIG. 5 is a schematic side view of a stream inoculation apparatus of the present invention;
FIG. 6 is a schematic view of an in-flow funnel of the in-flow inoculating device of the present invention;
FIG. 7 is a schematic top view of an alternative construction of the stream funnel of the stream inoculation apparatus of the present invention;
in the figure: 1. a transfer package; 2. spheroidizing the ladle; 3. a nodulizer; 4. a secondary inoculant; 5. a thin steel sheet; 6. a suspension arm; 7. a cross beam; 8. a flow following funnel; 9. a connecting rod; 10. a slideway; 11. a slider; 12. an electric push rod; 13. a plug; 14. pulling a rope; 15. a wiring groove; 16. and (4) a dam.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "middle", "upper", "lower", "left", "right", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
A novel spheroidizing inoculation method comprises the following operation steps:
as shown in fig. 1, (1) two ladles with the same specification are selected, one ladle is used as a transfer ladle 1, and the other ladle is used as a spheroidizing ladle 2;
(2) after the molten iron in the electric furnace is qualified, overheating to 1490 ℃, discharging the molten iron to the transfer ladle 1, pouring out the required weight (determined according to the actual total weight to be poured), and adding a primary inoculant into the transfer ladle 1;
(3) a nodulizer 3 and a secondary inoculant 4 are preset in the nodulizing ladle 2, the secondary inoculant 4 covers the upper part of the nodulizer 3, and a covering layer is arranged on the secondary inoculant 4;
(4) transporting the transfer ladle 1 and the spheroidizing ladle 2 to a pouring site, lifting the transfer ladle 1 to measure the weight and measure the temperature, quickly pouring molten iron into the spheroidizing ladle 2 at 1420 ℃, and adding a tertiary inoculant to one side of the spheroidizing ladle 2 while pouring the molten iron;
(5) during pouring, four-time inoculant is added along with the molten iron, and the adding amount of the four-time inoculant is 0.05-0.15%. The addition of the inoculant is calculated according to the percentage of the total pouring amount.
The spheroidizing inoculation method adopts the ladle-to-ladle spheroidizing inoculation treatment process, adopts multiple inoculation treatments in the processes of tapping, ladle-to-ladle and pouring, reasonably controls the addition amount of the inoculant at each time, obviously improves the inoculation effect, ensures that the spheroidizing effect is more ideal, has a large amount of graphite, good graphite form and stable mechanical property and metallographic structure, and can finally stably produce the qualified large-scale nodular iron casting.
Further, the primary inoculant in the transfer ladle 1 is flushed into the bottom of the ladle.
Further, a dam 16 is arranged at the bottom of the spheroidizing bag 2 on the side away from the sprue, the spheroidizing agent 3 is filled in a region surrounded by the dam 16 and the inner wall of the spheroidizing bag 2, the secondary inoculant 4 is filled on the surface of the spheroidizing agent 3 after the compacting and the flattening, a thin steel plate 5 is covered on the surface of the secondary inoculant 4 as the covering layer after the compacting and the flattening, and a covering agent is further arranged between the thin steel plate 5 and the secondary inoculant 4.
The surrounding of the dam 16 and the covering of the thin steel plate 5 are adopted, so that the phenomenon that a nodulizer and an inoculant are instantly dispersed when molten iron is added to cause poor inoculation and spheroidization can be avoided, and the inoculant and the nodulizer are dispersed and reacted in the molten iron after a certain amount of molten iron is filled to improve the spheroidization inoculation effect.
Further, the tertiary inoculant is added from one side of the spheroidizing ladle 2 along with the flow of the molten iron in the ladle pouring process.
Further, the fourth inoculant is added dynamically from above the nodulizing package 2 by means of a stream inoculation device.
Further, the nodulizer is a heavy RE nodulizer, and the main chemical components are Mg of 6, RE of 1.5, Ca of 2.1, Si of 43, Ba of 2.1 and Bi and Sb of about 0.5, which are all calculated according to wB (%).
The cooperation of Ba and Si in the nodulizer can lead the nodulizer to play a certain self-inoculation effect; the composition of Ca, Ba and Mg is favorable for easing the spheroidization reaction, improving the operating conditions and increasing the recovery rate of Mg
Further, the chemical components of the primary inoculant, the secondary inoculant and the tertiary inoculant are all arranged as follows: ca of 2, Ba of 5, Si of 69, and Bi and Sb of about 0.1, all in terms of wB (%), do not contain REO.
Further, the chemical components of the four-time inoculant are as follows: appropriate amounts of REO, 2.5 Ca, 4 Ba, 60 Si, 0.5 Bi and Sb, all in wB (%).
After spheroidizing, the supercooling degree of the molten iron is quite large, inoculation is very necessary and very effective, and the silicon series elements have the functions of strengthening inoculation and increasing graphite cores; ba. Ca and Ba-Ca have stronger inoculation fade resistance, while RE has weaker fade resistance. In an inoculant or a nodulizer, Bi and RE coexist, the number of graphite nodules can be obviously increased, the formation of a ferrite matrix is promoted, and the white cast tendency of a thin-wall ductile iron piece can be greatly reduced.
The first embodiment is as follows:
the spheroidizing inoculation method is adopted to produce the shell nodular iron casting with the average wall thickness of more than 60mm and the thickest part of 170mm, the net weight of the casting is 39t (upper shell) and 48t (lower shell), a plurality of parts are continuously produced for a plurality of times, the numbers of the castings are 1-2, 1-1, 2-2, 2-1, 3-2 and 3-1 in sequence, 40mm attached casting test blocks and 70mm attached casting test blocks are respectively arranged on the casting, and the corresponding metallographic structure and the mechanical property are shown in table 1.
The addition amount of the nodulizer is 1.1 percent, the addition amount of the primary inoculant is 0.2 percent, the addition amount of the secondary inoculant is 0.4 percent, the addition amount of the secondary inoculant is 0.07 percent,
the method comprises the following steps of selecting a charging material ratio of 43% of low-Mn stamping scrap steel and 57% of Q10 pig iron for melting and smelting, selecting 93% of carburant with carbon content, adding the carburant into a furnace along with the scrap steel in an early stage, adjusting the original Si content in the furnace by adopting FeSi, and smelting the original molten iron to have the following components:
C. 3.96 percent of Si, 1 percent of Mn, less than 0.3 percent of S, less than 0.025 percent of P, less than 0.04 percent of P and the balance of Fe;
the components of the nodular cast iron casting obtained after the spheroidizing inoculation treatment are basically as follows: w (C) 3.62%, w (Si) 2.6%, w (Mn) less than 0.3%, w (P) less than 0.04%, w (S) less than 0.025%, w (Mg) 0.04%, and the balance Fe.
TABLE 1 metallographic structure and mechanical properties of the cast test block
As can be seen from the table above, the castings obtained by continuous production have very good stability, the spheroidization grades of the castings in repeated production and batch production activities are both above grade 3, the graphite size grade is not less than grade 5, and the ferrite volume fraction is not less than 98%; all the mechanical properties exceed the national standard of corresponding grade castings (QT 400-15A). Fig. 2 and fig. 3 are metallographic pictures of two casting blocks attached to the upper shell of fig. 2-2, and it can be seen that graphite nodules are very uniform and round, and the spheroidization effect is very good.
The spheroidizing inoculation method obtains unexpected effects by adding the inoculant four times backwards, is not brought by simple frequency increase, has close relation with the adding time and the adding amount of the inoculant, has long waiting time of tapping molten iron and long solidification time of castings due to large wall thickness and heavy tonnage of thick and large section nodular cast iron, and can carry out spheroidizing inoculation on different time nodes and pipe fitting procedures by adding the inoculant in a fractional amount; the primary inoculant is added into the transfer ladle along with molten iron during tapping, the transfer ladle can be transferred to a balling ladle after waiting for a period of time, and the inoculant reacts in the transfer ladle to play a role of pre-adjustment in the process; a part of molten iron is directly discharged into the spheroidizing ladle, and since the secondary inoculant and the nodulizer are preset in the spheroidizing ladle, the molten iron starts to be spheroidized under the action of the secondary inoculant and the nodulizer after entering, and the process is just continued until the spheroidizing ladle is transported to a pouring site; in the casting site, the pretreated molten iron in the transfer ladle is poured into the spheroidizing ladle again for mixing, and the inoculant is added for three times along with the flow, so that the phenomena that the inoculant added in the initial stage is influenced by high temperature and decays for a long time are avoided, and the spheroidizing effect is better under the condition that the total addition amount of the inoculant and the addition amount of the spheroidizing agent are not increased; finally, the inoculant is added along with the molten iron flow for four times during the pouring of the molten iron, so that the spheroidization effect can be further strengthened, and the phenomenon of spheroidization recession of the molten iron in the long-term solidification process is less.
Example two:
this example provides a spheroidizing inoculating device used in the present spheroidizing inoculation method to enhance and ensure the inoculation effect.
As shown in fig. 4 and 5, the stream inoculation device comprises a stream following funnel 8 and connecting rods 9 for fixedly supporting the stream following funnel 8, wherein the two connecting rods 9 are symmetrically arranged on the periphery of the stream following funnel 8, and the connecting rods 9 are arranged in parallel to a cross beam 7 above a suspension arm 6 of the balling ladle 2; a vertical slide way 10 is arranged on the outer side of the suspension arm 6, a slide block 11 is arranged on the slide way 10, an electric push rod 12 is arranged on the slide block 11, and the output end of the electric push rod 12 is connected with the end part of the connecting rod 9; a plug 13 is arranged at an outlet at the lower end of the flow following funnel 8, a pull rope 14 is connected to the plug 13, wire grooves 15 are respectively formed in the surfaces of the flow following funnel 8 and the connecting rod 9, and the pull rope 14 is led to the outside of the balling ladle 2 along the wire grooves 15.
The position of the stream following funnel 8 can be flexibly adjusted through the arrangement of the stream following inoculation device, and in the inclined pouring process of the spheroidizing bag 2, the stream following funnel 8 can also move, so that the added four-time inoculant can better flow into a cavity along with the molten iron flow, dynamic addition is realized, the addition position can be more reasonably controlled, and the problem of inconsistent addition caused by the fact that the spheroidizing bag 2 is inclined and the addition position is unchanged is avoided; and the safety is higher after setting up like this, can remote control, has avoided the workman to be close to closely to the ladle.
The inoculant for stream inoculation can be arranged in the stream following funnel 8 in advance, and the transfer of molten iron in the ladle pouring process is not influenced by controlling the high-low internal and external positions of the stream following funnel 8.
When the device is used, the sliding block 11 is controlled by the motor to move up and down along the slide way 10, and the electric push rod 12, the connecting rod 9 and the following funnel 8 are lifted together; the electric push rod 12 can be controlled to simultaneously drive the pair of connecting rods 9 to move inwards or outwards, so that the horizontal position of the accompanying funnel 8 is adjusted.
The slide block 11 and the electric push rod 12 are arranged on the outer side of the suspension arm 6, so that the electric control components can be prevented from being directly baked at high temperature.
The arrangement of the cabling slot 15 facilitates the regular leading-out of the pull rope 14. As shown in fig. 6, in order to temporarily fix the pulling rope 14, virtual hooks may be provided on the outside of the cabling channel 15, below the electric push rod and below the slider, and when in use, the hooks can be pulled or pulled off without affecting the pulling of the pulling rope 14 downward to take out the plug 13.
Example three:
this embodiment provides an alternate construction of the drag funnel.
As shown in fig. 7, the upper part of the following flow funnel 8 is cylindrical, the lower part is a conical discharging part, the section of the discharging part is of an inverted trapezoidal bin structure, and an anti-adhesion coating layer is arranged on the inner side of the following flow funnel 8; the anti-adhesion coating is a silicon crystal ceramic coating coated on the wall of the bin, so that the friction force can be reduced, and the smooth outflow of the inoculant is facilitated.
Further, the connecting rod 9 is symmetrically welded on the cylindrical periphery of the flow following funnel 8, and a reinforcing transition plate is arranged at the welding position to improve the connection strength.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (10)
1. A novel spheroidizing inoculation method is characterized by comprising the following operation steps:
(1) selecting two foundry ladles, one as a transfer ladle and the other as a spheroidizing ladle;
(2) after the components of the molten iron in the furnace are qualified, overheating to 1480-1500 ℃, discharging the molten iron to the transfer ladle, and adding a primary inoculant into the transfer ladle in an amount of 0.1-0.3%;
(3) a nodulizer and a secondary inoculant are preset in the nodulizing ladle, the addition amount of the nodulizer is 1.0-1.4%, the addition amount of the secondary inoculant is 0.3-0.6%, the secondary inoculant covers the nodulizer, and a covering layer is arranged on the secondary inoculant;
(4) transporting the transfer ladle and the spheroidizing ladle to a pouring site, hoisting the transfer ladle to measure weight and measure temperature, quickly pouring molten iron into the spheroidizing ladle at 1400-1460 ℃, and adding a tertiary inoculant into the spheroidizing ladle while pouring the molten iron, wherein the addition amount of the tertiary inoculant is 0.2-0.5%;
(5) during pouring, four-time inoculant is added along with the molten iron, and the adding amount of the four-time inoculant is 0.05-0.15%.
2. The novel spheroidizing inoculation method according to claim 1, wherein the primary inoculant in the transfer ladle is flushed into the bottom of the transfer ladle, and the primary inoculant is a Ba-containing inoculant with the granularity of 5-15 mm.
3. The novel spheroidizing inoculation method according to claim 1, wherein a dam is arranged at the bottom of the spheroidizing bag on the side away from a sprue, the spheroidizing agent is filled in a region enclosed by the dam and the inner wall of the spheroidizing bag, the secondary inoculant is filled on the surface of the spheroidizing agent after the compacting and the compacting are carried out, a thin steel plate is covered on the surface of the secondary inoculant to serve as the covering layer after the compacting and the compacting are carried out, and a covering agent is further arranged between the thin steel plate and the secondary inoculant; the secondary inoculant is also a Ba-containing inoculant with granularity of 5-15 mm.
4. The novel spheroidizing inoculation method according to claim 1, wherein the tertiary inoculant is added from one side of the spheroidizing ladle in a flowing manner with molten iron in the ladle pouring process, and the tertiary inoculant is also a Ba-containing inoculant with the granularity of 5-15 mm.
5. The novel spheroidizing inoculation method according to claim 1, wherein the fourth-time inoculant is added from above the spheroidizing bag through a stream inoculation device, and the fourth-time inoculant is a Bi-containing inoculant with the granularity of 0.5-1.5 mm.
6. The novel spheroidizing inoculation method according to claim 1, wherein the spheroidizing agent is a heavy RE spheroidizing agent, and the main chemical components are Mg with the weight of 5-8, RE with the weight of 1.0-2.0, Ca with the weight of 1.5-2.5, Si with the weight of 42-45, a small amount of Ba, and trace amounts of Bi and Sb, all calculated according to wB (%).
7. The novel spheroidizing inoculation method according to claim 1, wherein the chemical compositions of the primary inoculant, the secondary inoculant and the tertiary inoculant are all set as follows: 1-3 Ca, 4-6 Ba, 67-72 Si, and trace amounts of Bi and Sb, all in terms of wB (%), without REO.
8. The novel spheroidizing inoculation method according to claim 1, wherein the chemical composition of the quaternary inoculant is as follows: a small amount of REO, 2-3 Ca, 3-5 Ba, 55-65 Si, and a small amount of Bi and Sb, all in terms of wB (%).
9. The novel spheroidizing inoculation method according to claim 1, characterized in that a charging material ratio of 40% -60% of low Mn stamping scrap and 60% -40% of Q10 pig iron is selected for melting smelting, a carburant with 93% of carbon content is selected and added in the furnace along with the scrap at the early stage, FeSi is adopted to adjust the original Si content in the furnace, and the qualified components of the original molten iron after smelting are as follows:
C. 3.9-4.1% of Si, 0.9-1.2% of Mn, less than 0.3% of S, less than 0.025% of P, and the balance of Fe;
the components of the nodular cast iron casting obtained after spheroidizing inoculation are as follows: w (C) 3.5-3.9%, w (Si) 2.0-2.7%, w (Mn) less than 0.3%, w (P) less than 0.04%, w (S) less than 0.025%, w (Mg) 0.04-0.06%, and the balance Fe.
10. The novel spheroidization inoculation method according to claim 5, wherein the stream inoculation device comprises a stream following funnel and connecting rods for fixedly supporting the stream following funnel, the connecting rods are two symmetrically arranged at the periphery of the stream following funnel, and the connecting rods are arranged in parallel to a cross beam above a suspension arm of the spheroidization ladle; a vertical slide way is arranged on the outer side of the suspension arm, a slide block is arranged on the slide way, an electric push rod is arranged on the slide block, and the output end of the electric push rod is connected with the end part of the connecting rod; the outlet of the lower end of the flow following funnel is provided with a plug, the plug is connected with a pull rope, the surfaces of the flow following funnel and the connecting rod are respectively provided with a wiring groove, and the pull rope is led to the outside of the balling ladle along the wiring grooves.
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| CN115255294A (en) * | 2022-06-13 | 2022-11-01 | 天润工业技术股份有限公司 | Treatment process for producing high-strength and high-toughness nodular cast iron through green sand molding |
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| CN115537643A (en) * | 2022-10-18 | 2022-12-30 | 山东湖西王集团铸业有限公司 | Preparation method and system for stably producing low-temperature impact nodular cast iron in cast state |
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