CN113523205B - Spheroidizing inoculation method - Google Patents
Spheroidizing inoculation method Download PDFInfo
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- CN113523205B CN113523205B CN202110764080.8A CN202110764080A CN113523205B CN 113523205 B CN113523205 B CN 113523205B CN 202110764080 A CN202110764080 A CN 202110764080A CN 113523205 B CN113523205 B CN 113523205B
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- inoculant
- ladle
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- 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 spheroidizing inoculation method, which selects two ladles as a transfer ladle and a spheroidizing ladle respectively; the molten iron in the furnace is overheated to 1480-1500 ℃ after being qualified, the molten iron is discharged to a transfer ladle, the required weight is poured out, and a primary inoculant is added into the transfer ladle; a nodulizing agent and a secondary inoculant are preset in the nodulizing bag; the transfer ladle and the spheroidizing ladle are transported to a pouring site, the transfer ladle is lifted for weighing and measuring the temperature, molten iron is rapidly poured into the spheroidizing ladle at the temperature of 1400-1460 ℃, and a tertiary inoculant is added into the spheroidizing ladle while molten iron is poured; during pouring, adding a fourth inoculant along with the molten iron along with the flow; the method adopts the treatment process of ladle-to-ladle spheroidization inoculation, reasonably controls the addition amount of inoculant each time, obviously improves the inoculation effect, ensures that the spheroidization effect is more ideal, has a large quantity of graphite, good graphite morphology and stable mechanical properties and metallographic structure, and finally can stably produce qualified large-sized spheroidal iron pieces.
Description
Technical Field
The invention relates to the technical field of casting, in particular to a spheroidizing inoculation method.
Background
Because the thick and large section nodular cast iron casting is easy to generate abnormal graphite such as bloom, fragments, coarse and the like, and because the liquid cooling and solidification time is long, phenomena such as spheroidization degradation and inoculation degradation can be generated, the phenomena can influence a matrix structure, and the mechanical property of the casting is seriously deteriorated.
At present, the large-scale ductile iron is generally produced by adopting a traditional impact method spheroidizing process, namely, adding a spheroidizing agent and an inoculant into a spheroidizing ladle bottom, and adding a secondary follow-up flow process during casting, wherein the process has the defects of small spheroidizing temperature controllability and insufficient inoculation times, so that the quantity and form difference of graphite after spheroidization are larger, finally, the mechanical property and metallographic structure are not in accordance with the requirements, and the production is unstable.
For example, china patent (publication No. CN 103805731B) discloses a preparation method of nodular cast iron alloy in 2016, which comprises ladle inoculation, ladle inversion inoculation and stream inoculation. The invention adds a ladle-to-ladle inoculation process between the original two steps of nodulizing ladle inoculation and stream inoculation, thereby realizing a special instantaneous multi-inoculation process; however, the ladle-to-ladle inoculation mode is more suitable for the production of small-sized ductile iron castings, and has no obvious effect on the production of large-sized and large-tonnage ductile iron castings.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a spheroidizing inoculation method, optimizes the molten iron before spheroidizing so as to provide a good spheroidizing platform, stably controls the temperature required by spheroidizing, increases the times in the spheroidizing inoculation process, greatly improves the quantity and the morphology of graphite after spheroidizing, and finally stably produces qualified large-sized spheroidal iron castings by obtaining stable mechanical properties and metallographic structures.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a spheroidizing inoculation method comprises the following operation steps:
(1) Two ladles are selected, one is used as a transfer ladle and the other is used as a spheroidizing ladle;
(2) The molten iron in the furnace is overheated to 1480-1500 ℃ after being qualified, the molten iron is discharged to the transfer ladle and poured out to the required weight, and a primary inoculant is added into the transfer ladle, wherein the addition amount is 0.1-0.3%;
(3) A nodulizing agent and a secondary inoculant are preset in the nodulizing bag, the adding amount of the nodulizing agent is 1.0% -1.4%, the adding amount of the secondary inoculant is 0.3% -0.6%, the secondary inoculant covers the upper part of the nodulizing agent, and a covering layer is arranged on the secondary inoculant;
(4) The transfer ladle and the spheroidizing ladle are transported to a pouring site, the transfer ladle is lifted for weighing and measuring the temperature, molten iron is rapidly poured into the spheroidizing ladle at the temperature of 1400-1460 ℃, and a tertiary inoculant is added into the spheroidizing ladle while molten iron is poured, wherein the addition amount of the tertiary inoculant is 0.2-0.5%;
(5) And during pouring, adding a fourth inoculant along the molten iron along with the flow, wherein the adding amount of the fourth inoculant is 0.05-0.15%. The addition amount of the inoculant is calculated according to the percentage of the total casting amount.
The spheroidizing inoculation treatment method adopts a treatment process of ladle-to-ladle spheroidizing inoculation, adopts multiple inoculation treatments in the tapping, ladle-to-ladle and pouring processes, reasonably controls the addition amount of inoculant each time, obviously improves the inoculation treatment effect, ensures that the spheroidizing effect is more ideal, has a large quantity of graphite, good graphite morphology and stable mechanical property and metallographic structure, and finally can stably produce qualified large-sized spheroidal iron pieces.
The spheroidizing inoculation method has the advantages that unexpected effects are obtained by adding inoculant four times backwards, the unexpected effects are not brought by the simple increase of times, the adding time and the adding amount of the inoculant are closely related, because the thick and large-section spheroidal graphite cast is large in wall thickness and heavy in tonnage, the required molten iron amount for one-time pouring is very large, the waiting time of tapping molten iron and the solidification time of the cast are long, and the spheroidizing inoculation can be carried out 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 needs to wait for one end time to be transferred to the spheroidizing ladle, and the inoculant reacts in the transfer ladle to play a role of preconditioning in the process; and part of molten iron directly flows out of the ladle, and the secondary inoculant and the nodulizer are preset in the ladle, so that the molten iron starts to change in a nodulizing way under the action of the secondary inoculant and the nodulizer after entering, and the process just lasts until the ladle is transported to a pouring site; in the pouring 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 phenomenon that the inoculant added in the early stage is influenced by high temperature and decayed for a long time is avoided, and the spheroidizing effect is better under the condition that the total inoculant addition amount and the spheroidizing agent addition amount are not increased; and finally, adding the inoculant for four times along with the flow during pouring of the molten iron can further consolidate the spheroidization effect, and ensure that the phenomenon of spheroidization degradation of the molten iron in a long-term solidification process is less.
By adopting the spheroidizing inoculation method, the quality stability of the produced spheroidal graphite cast is very good, the spheroidization grade of the cast which is repeatedly produced and mass-produced is more than 3, the graphite size grade is not less than 5, and the ferrite volume fraction is not less than 98%.
Further, the primary inoculant in the transfer package is poured into the bottom of the primary package, and the primary inoculant is Ba-containing inoculant with the granularity of 5-15 mm. The inoculant containing Ba can promote graphitization, reduce the tendency of white mouth, improve the morphology and distribution of graphite, increase the quantity of eutectic cells and refine matrix tissues, and has good effect after inoculation for a period of time, which is enough to connect with the next inoculation.
Further, a dam is arranged at the ladle bottom of one side of the spheroidizing ladle, which is far away from the pouring gate, a region surrounded by the dam and the inner wall of the spheroidizing ladle is filled with the spheroidizing agent, the surface of the spheroidizing agent is filled with the secondary inoculant after compaction, a thin steel plate is covered on the surface of the secondary inoculant as the covering layer after compaction, 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 the granularity of 5-15 mm.
The surrounding of the dykes and dams and the covering of the thin steel plates are adopted, so that the phenomenon of bad inoculation spheroidization caused by instant scattering of 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 third inoculant is added along with the flowing of molten iron from one side of the spheroidizing ladle in the ladle pouring process, and the third inoculant is also a Ba-containing inoculant with the granularity of 5-15 mm.
Further, the quaternary inoculant is added from the upper part of the nodulizing ladle through a stream inoculation device, and the quaternary inoculant is a Bi-containing inoculant with the granularity of 0.5-1.5 mm. The Bi-containing inoculant with finer particles is suitable for stream inoculation and addition, and is beneficial to accurate control of inoculation amount.
Further, the nodulizer is a heavy RE nodulizer, and the main chemical components of the nodulizer 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 small amount of Bi and Sb (such as within 0.1), and the balance of Fe, wherein the balance of Fe is calculated according to wB (%), and the nodulizer can be commercially available products.
Further, the chemical components of the primary inoculant, the secondary inoculant and the tertiary inoculant are all set as follows: 1 to 3 Ca, 4 to 6 Ba, 67 to 72 Si, trace Bi and Sb (0.1 to 1), and the balance of Fe, wherein the balance of Fe is calculated according to wB (%), no REO is contained, and commercially available products such as nodulizer and inoculant produced by Longtong yttrium heavy rare earth science and technology Co.
Further, the chemical components of the quaternary inoculant are as follows: small amounts of REO (less than 1), ca 2 to 3, ba 3 to 5, si 55 to 65, small amounts of Bi and Sb (less than 1), and the balance Fe, all in terms of wB (%).
Further, the burden proportion of 40-60% of low Mn stamping scrap steel and 60-40% of Q10 pig iron is selected for smelting, 93% of carburant with carbon content is selected, the carburant is added in the furnace along with the earlier stage of scrap steel, feSi is adopted to adjust the amount of raw Si in the furnace, and the qualified components of the raw iron liquid after smelting are as follows:
C. 3.9 to 4.1 percent, si, 0.9 to 1.2 percent, mn less than 0.3 percent, S less than 0.025 percent, P less than 0.04 percent and the balance of Fe;
the spheroidal graphite cast iron casting obtained after the spheroidizing inoculation treatment comprises the following components: 3.5 to 3.9 percent of w (C), 2.0 to 2.7 percent of w (Si), less than 0.3 percent of w (Mn), less than 0.04 percent of w (P), less than 0.025 percent of w (S), 0.04 to 0.06 percent of w (Mg) and the balance of Fe.
That is, after the spheroidizing inoculation, the obtained casting is greatly improved in spheroidization grade and graphite grade, the C, si content is improved, the residual magnesium content is lower, and the mechanical property of the spheroidal graphite casting is improved.
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 parallel to a cross beam above a suspension arm of the spheroidizing bag; the outer side of the suspension arm is provided with a vertical slideway, a sliding block is arranged on the slideway, an electric push rod is arranged on the sliding block, and the output end of the electric push rod is connected with the end part of the connecting rod; the lower extreme exit of flow-following funnel is equipped with the stopper, be connected with the stay cord on the stopper, flow-following funnel with the wiring groove has been seted up respectively to the surface of connecting rod, the stay cord is followed the wiring groove is led to the outside of balling package.
Through the arrangement of the stream inoculation device, the position of the stream following funnel can be flexibly adjusted, and in the process of oblique pouring of the spheroidizing ladle, the stream following funnel can also move, so that the added quaternary inoculant can better flow into a cavity along with molten iron stream, the adding position can be controlled more reasonably, and the problem of inconsistent adding caused by unchanged adding position due to the inclination of the spheroidizing ladle is avoided; and the safety is higher after setting up like this, can remote control, avoided the workman to be close to the ladle closely.
The inoculant for stream inoculation can be preset in the stream following funnel, and the transfer of molten iron in the pouring process is not influenced by controlling the inner and outer positions of the stream following funnel.
When the device is used, the motor is used for controlling the sliding block to move up and down along the slideway, and the electric push rod, the connecting rod and the flow following funnel are lifted together; the electric push rod is controlled to drive the connecting rod to move inwards or outwards simultaneously, so that the horizontal position of the flow 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 extraction of the pull rope.
Compared with the prior art, the invention has the beneficial effects that: 1. the spheroidizing inoculation treatment method adopts a treatment process of ladle-to-ladle spheroidizing inoculation, adopts repeated inoculation treatment in the tapping, ladle-to-ladle and pouring processes, reasonably controls the addition amount of inoculant each time, obviously improves the inoculation effect, ensures that the spheroidizing effect is more ideal, has a plurality of graphite quantities, good graphite morphology and stable mechanical properties and metallographic structure, and can finally stably produce qualified large-sized spheroidal iron pieces; 2. by adopting the spheroidizing inoculation method, the quality stability of the produced spheroidal graphite cast is very good, the spheroidization grade of the cast which is produced repeatedly and in mass production activities is above grade 3, the graphite size grade is not less than grade 5, and the ferrite volume fraction is not less than 98%; 3. after the spheroidizing inoculation treatment, the obtained casting is greatly improved in spheroidization grade and graphite grade, the content of C, si is improved, and the mechanical property of the spheroidal graphite casting is also improved; 4. through the arrangement of the stream inoculation device, the position of the stream following funnel can be flexibly adjusted, and in the process of oblique pouring of the spheroidizing ladle, the stream following funnel can also move, so that the added inoculant can better follow molten iron stream to flow into a cavity together, the adding position can be controlled more reasonably, and the spheroidizing inoculation effect can be improved; and the safety is higher after the arrangement, and the remote control can be realized.
Drawings
FIG. 1 is a schematic diagram of ladle pouring in a spheroidizing inoculation process according to the present invention;
FIG. 2 is a metallographic structure of a 40mm attached cast test block of the lower shell obtained by the spheroidization inoculation method of the present invention;
FIG. 3 shows the metallographic structure of a 70mm cast-attached specimen of the lower shell obtained by the spheroidization inoculation method of the present invention;
FIG. 4 is a schematic front view of a stream inoculating device of the present invention;
FIG. 5 is a schematic side view of a stream inoculating device of the present invention;
FIG. 6 is a schematic diagram of a stream hopper of the stream inoculation apparatus of the present invention;
FIG. 7 is a schematic top view of another embodiment of a stream hopper of the stream inoculation apparatus of the present invention;
in the figure: 1. a transfer bag; 2. spheroidizing bag; 3. a nodulizing agent; 4. a secondary inoculant; 5. a thin steel plate; 6. a suspension arm; 7. a cross beam; 8. a flow-following funnel; 9. a connecting rod; 10. a slideway; 11. a slide block; 12. an electric push rod; 13. a plug; 14. a pull rope; 15. wiring grooves; 16. dykes and dams.
Detailed Description
The following description of the embodiments of the present invention will be made more apparent and fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by one of ordinary skill in the art without undue burden on the person of ordinary skill in the art based on embodiments of the present invention, are within the scope of the present invention.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "middle", "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or element to be referred to must have a specific orientation, be constructed and operated in a specific orientation, 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 spheroidizing inoculation method comprises the following operation steps:
as shown in fig. 1, (1) two ladles with the same specification are selected, one is used as a transfer ladle 1, and the other is used as a spheroidizing ladle 2;
(2) The molten iron in the electric furnace is overheated to 1490 ℃ after being qualified, the molten iron is discharged to the transfer ladle 1 and poured out to a required weight (determined according to the total weight to be actually poured), and a primary inoculant is added into the transfer ladle 1;
(3) A nodulizing agent 3 and a secondary inoculant 4 are preset in the nodulizing ladle 2, the secondary inoculant 4 is covered above the nodulizing agent 3, and a covering layer is arranged on the secondary inoculant 4;
(4) The transfer ladle 1 and the spheroidizing ladle 2 are transported to a pouring site, the transfer ladle 1 is lifted for weighing and measuring the temperature, molten iron is rapidly poured into the spheroidizing ladle 2 at the temperature of 1420 ℃, and a tertiary inoculant is added to one side of the spheroidizing ladle 2 while molten iron is poured;
(5) And during pouring, adding a fourth inoculant along the molten iron along with the flow, wherein the adding amount of the fourth inoculant is 0.05-0.15%. The addition amount of the inoculant is calculated according to the percentage of the total casting amount.
The spheroidizing inoculation treatment method adopts a treatment process of ladle-to-ladle spheroidizing inoculation, adopts multiple inoculation treatments in the tapping, ladle-to-ladle and pouring processes, reasonably controls the addition amount of inoculant each time, obviously improves the inoculation treatment effect, ensures that the spheroidizing effect is more ideal, has a large quantity of graphite, good graphite morphology and stable mechanical property and metallographic structure, and finally can stably produce qualified large-sized spheroidal iron pieces.
Further, the primary inoculant in the transfer ladle 1 is injected into the bottom of the primary ladle.
Further, a dam 16 is arranged at the ladle bottom of the spheroidizing ladle 2 at one side far away from the pouring gate, the spheroidizing agent 3 is filled in an area surrounded by the dam 16 and the inner wall of the spheroidizing ladle 2, the secondary inoculant 4 is filled in the surface of the spheroidizing agent 3 after compaction, the steel sheet 5 is covered on the surface of the secondary inoculant 4 as the covering layer after compaction, and a covering agent is further arranged between the steel sheet 5 and the secondary inoculant 4.
The adoption of the surrounding of the dykes and dams 16 and the covering of the thin steel plates 5 can avoid the phenomenon that the nodulizer and the inoculant are instantaneously dispersed to cause bad inoculation and spheroidization when the molten iron is added, and the arrangement can ensure that the inoculant and the nodulizer are dispersed and reacted in the molten iron after the molten iron is filled with a certain amount, so that the spheroidization and inoculation effects are improved.
Further, the third inoculant is added from one side of the nodulizing ladle 2 along with the flowing of molten iron in the ladle pouring process.
Further, the fourth inoculant is dynamically added from above the nodulizing ladle 2 by a stream inoculation device.
Further, the spheroidizing agent is a heavy RE spheroidizing agent, and the main chemical components of the spheroidizing agent are 6 Mg, 1.5 RE, 2.1 Ca, 43 Si, 2.1 Ba, about 0.5 Bi and Sb, and the weight is calculated according to wB (%).
The cooperation of Ba and Si in the nodulizer can lead the nodulizer to exert certain self-inoculation effect; compounding Ca, ba and Mg is favorable for alleviating spheroidization reaction, improving operation 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 set as follows: ca of 2, ba of 5, si of 69, bi of about 0.1 and Sb, in terms of wB (%), do not contain REO.
Further, the chemical components of the quaternary inoculant are as follows: the amounts of REO, ca of 2.5, ba of 4, si of 60, bi of 0.5 and Sb were calculated as wB (%).
After spheroidizing treatment, the supercooling degree of the molten iron is quite large, the inoculation is very necessary and very effective, and all the silicon elements have the effects of strengthening inoculation and increasing graphite cores; ba. Ca and Ba-Ca have stronger inoculation and decay resistance, while RE has weaker decay resistance. In the inoculant or the nodulizer, bi and RE coexist, so that the graphite nodule count can be obviously increased, the ferrite matrix can be promoted to be formed, and the white mouth tendency of the thin-wall nodular iron piece can be greatly reduced.
Embodiment one:
the average wall thickness of the shell spheroidal graphite cast iron with the thickness of 170mm is produced by adopting the spheroidizing inoculation method, the net weight of the casting is 39t (upper shell) and 48t (lower shell), a plurality of castings are continuously produced for multiple times, the numbers of the castings are 1-2, 1-1, 2-2, 2-1, 3-2 and 3-1 in sequence, 40mm additional casting test blocks and 70mm additional casting test blocks are respectively arranged on the castings, and the corresponding metallographic structures and mechanical properties 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 steps of selecting 43% of low-Mn stamping scrap steel scraps and 57% of Q10 pig iron furnace burden to carry out smelting, selecting 93% of carburant with carbon content, adding the carburant in a furnace along with the scrap steel in the early stage, adopting FeSi to adjust the raw Si content in the furnace, and adopting the following raw iron liquid after smelting:
C. 3.96%, si, 1%, mn less than 0.3%, S less than 0.025%, P less than 0.04%, the remainder being Fe;
the spheroidal graphite cast iron casting obtained after the spheroidization inoculation treatment basically comprises the following components: 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%, the remainder being Fe.
Table 1 metallographic structure and mechanical properties of the additional cast test pieces
As can be seen from the table, the casting obtained by continuous production has very good stability, the spheroidization grade of castings produced repeatedly and in mass production activities is above grade 3, the grade of graphite size is not less than grade 5, and the ferrite volume fraction is not less than 98%; the mechanical properties of the alloy are all over the national standard of corresponding grade castings (QT 400-15A). Fig. 2 and 3 are metallographic pictures of two additional casting test blocks of the upper shell of 2-2, and can show that the graphite nodules are very uniform and round, and the spheroidization effect is very good.
The spheroidizing inoculation method has the advantages that unexpected effects are obtained by adding inoculant four times backwards, the unexpected effects are not brought by the simple increase of times, the adding time and the adding amount of the inoculant are closely related, because the thick and large-section spheroidal graphite cast is large in wall thickness and heavy in tonnage, the required molten iron amount for one-time pouring is very large, the waiting time of tapping molten iron and the solidification time of the cast are long, and the spheroidizing inoculation can be carried out 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 needs to wait for one end time to be transferred to the spheroidizing ladle, and the inoculant reacts in the transfer ladle to play a role of preconditioning in the process; and part of molten iron directly flows out of the ladle, and the secondary inoculant and the nodulizer are preset in the ladle, so that the molten iron starts to change in a nodulizing way under the action of the secondary inoculant and the nodulizer after entering, and the process just lasts until the ladle is transported to a pouring site; in the pouring 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 phenomenon that the inoculant added in the early stage is influenced by high temperature and decayed for a long time is avoided, and the spheroidizing effect is better under the condition that the total inoculant addition amount and the spheroidizing agent addition amount are not increased; and finally, adding the inoculant for four times along with the flow during pouring of the molten iron can further consolidate the spheroidization effect, and ensure that the phenomenon of spheroidization degradation of the molten iron in a long-term solidification process is less.
Embodiment two:
the present embodiment provides a spheroidizing inoculating device used in the spheroidizing inoculating method to improve and ensure the inoculating effect.
As shown in fig. 4 and 5, the stream inoculation device comprises a stream following funnel 8 and two connecting rods 9 for fixedly supporting the stream following funnel 8, wherein the two connecting rods 9 are symmetrically arranged at the periphery of the stream following funnel 8, and the connecting rods 9 are parallel to a cross beam 7 above a suspension arm 6 of the nodulizing ladle 2; the outer side of the suspension arm 6 is provided with a vertical slideway 10, the slideway 10 is provided with a sliding block 11, the sliding block 11 is provided with an electric push rod 12, and the output end of the electric push rod 12 is connected with the end part of the connecting rod 9; the outlet of the lower end of the flow following funnel 8 is provided with a plug 13, the plug 13 is connected with a pull rope 14, the surfaces of the flow following funnel 8 and the connecting rod 9 are respectively provided with a wiring groove 15, and the pull rope 14 is led to the outside of the spheroidizing bag 2 along the wiring grooves 15.
Through the arrangement of the stream inoculation device, the position of the stream following funnel 8 can be flexibly adjusted, and in the process of obliquely pouring the spheroidizing ladle 2, the stream following funnel 8 can also move, so that the added four inoculants can better flow into a cavity along with molten iron stream, the dynamic addition is realized, the addition position can be controlled more reasonably, and the problem of inconsistent addition caused by the fact that the addition position is unchanged due to the inclination of the spheroidizing ladle 2 is avoided; and the safety is higher after setting up like this, can remote control, avoided the workman to be close to the ladle closely.
The inoculant for stream inoculation can be preset in the stream following funnel 8, and the transfer of molten iron in the pouring process is not influenced by controlling the inner and outer positions of the stream following funnel 8.
When in use, the motor controls the sliding block 11 to move up and down along the slideway 10, and the electric push rod 12, the connecting rod 9 and the flow following funnel 8 are lifted together; the electric push rod 12 is controlled to drive the pair of connecting rods 9 to move inwards or outwards simultaneously, so that the horizontal position of the flow-following funnel 8 is adjusted.
The sliding 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 wiring groove 15 facilitates the regular extraction of the pull rope 14. As shown in fig. 6, in order to temporarily fix the pull cord 14, virtual hooks may be provided on the outer side of the wiring groove 15, below the electric push rod, and below the slider, and in use, the hooks may be pulled or pulled away without affecting the pulling of the pull cord 14 downward to bring the plug 13 out.
Embodiment III:
the present embodiment provides another construction of the flow-following funnel.
As shown in fig. 7, the upper part of the flow following funnel 8 is cylindrical, the lower part is a conical discharging part, the section of the discharging part is of an inverted trapezoid stock bin structure, and an anti-adhesion coating layer is arranged on the inner side of the flow following funnel 8; the anti-adhesion coating is a silicon crystal porcelain coating painted on the bin wall, so that friction force can be reduced, and 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 reinforced 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 understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (9)
1. The spheroidizing inoculation method is characterized by comprising the following operation steps of:
(1) Two ladles are selected, one is used as a transfer ladle and the other is used as a spheroidizing ladle;
(2) The molten iron in the furnace is overheated to 1480-1500 ℃ after being qualified, the molten iron is discharged to the transfer ladle, and a primary inoculant is added into the transfer ladle, wherein the addition amount is 0.1-0.3%;
(3) A spheroidizing agent and a secondary inoculant are preset in the spheroidizing bag, the adding amount of the spheroidizing agent is 1.0% -1.4%, the adding amount of the secondary inoculant is 0.3% -0.6%, the secondary inoculant covers the upper part of the spheroidizing agent, a covering layer is arranged on the secondary inoculant, the covering layer is a thin steel plate, and a covering agent is further arranged between the thin steel plate and the secondary inoculant;
(4) The transfer ladle and the spheroidizing ladle are transported to a pouring site, the transfer ladle is lifted for weighing and measuring the temperature, molten iron is rapidly poured into the spheroidizing ladle at the temperature of 1400-1460 ℃, and a tertiary inoculant is added into the spheroidizing ladle while molten iron is poured, wherein the addition amount of the tertiary inoculant is 0.2-0.5%;
the primary inoculant is added into the transfer ladle along with molten iron during tapping, the transfer ladle needs to wait for a period of time to be transferred to the spheroidizing ladle, and the inoculant reacts in the transfer ladle to play a role of preconditioning in the process; and part of molten iron directly flows out of the ladle, and the secondary inoculant and the nodulizer are preset in the ladle, so that the molten iron starts to change in a nodulizing way under the action of the secondary inoculant and the nodulizer after entering, and the process just lasts until the ladle is transported to a pouring site; pouring the pretreated molten iron in the transfer ladle into a pelletization ladle again for mixing at a pouring site, and adding a third inoculant along with the flow;
(5) During pouring, adding a fourth inoculant along the molten iron along with the flow, wherein the adding amount of the fourth inoculant is 0.05-0.15%;
wherein the primary inoculant is a Ba-containing inoculant with the granularity of 5-15 mm; the secondary inoculant is also a Ba-containing inoculant with the granularity of 5-15 mm; the third inoculant is also a Ba-containing inoculant with the granularity of 5-15 mm; the fourth inoculant is a Bi-containing inoculant with the granularity of 0.5-1.5 mm;
the method comprises the steps of selecting 40% -60% of low Mn stamping scrap steel scrap and 60% -40% of Q10 pig iron burden to carry out smelting, selecting 93% of carbon carburant, adding the carburant in a furnace along with the early stage of scrap steel, adjusting the amount of raw Si in the furnace by adopting FeSi, and the qualified components of the raw iron liquid after smelting are as follows:
C. 3.9 to 4.1 percent, si, 0.9 to 1.2 percent, mn less than 0.3 percent, S less than 0.025 percent, P less than 0.04 percent and the balance of Fe;
the spheroidal graphite cast iron casting obtained after spheroidizing inoculation comprises the following components: 3.5 to 3.9 percent of w (C), 2.0 to 2.7 percent of w (Si), less than 0.3 percent of w (Mn), less than 0.04 percent of w (P), less than 0.025 percent of w (S), 0.04 to 0.06 percent of w (Mg) and the balance of Fe.
2. The spheroidization inoculation method according to claim 1, wherein the primary inoculant in the transfer ladle is underfilled.
3. The spheroidizing inoculation method according to claim 1, wherein a dam is arranged at the ladle bottom at the side of the spheroidizing ladle, which is far away from the pouring gate, the spheroidizing agent is filled in the area surrounded by the dam and the inner wall of the spheroidizing ladle, the secondary inoculant is filled in the surface of the spheroidizing agent after compaction, and the steel sheet is covered after compaction.
4. The spheroidizing inoculant process according to claim 1, wherein the tertiary inoculant is added from one side of the spheroidizing ladle with molten iron flow during the ladle pouring process.
5. The spheroidization inoculation method according to claim 1, wherein the quaternary inoculant is added from above the spheroidization package by a stream inoculation device.
6. The spheroidizing inoculation method according to claim 1, wherein the spheroidizing agent is a heavy RE spheroidizing agent, and the main chemical components are 5-8 Mg, 1.0-2.0 RE, 1.5-2.5 Ca, 42-45 Si, a small amount of Ba, and a trace amount of Bi and Sb, all calculated as wB (%).
7. The spheroidizing inoculant process as claimed in claim 1, wherein the chemical composition of the primary inoculant, the secondary inoculant and the tertiary inoculant are all set as follows: 1 to 3 Ca, 4 to 6 Ba, 67 to 72 Si, and trace amounts of Bi and Sb, all calculated as wB (%), do not contain REO.
8. The spheroidizing inoculant process as claimed in claim 1, wherein the quaternary inoculant comprises the following chemical components: small amounts of REO, 2 to 3 Ca, 3 to 5 Ba, 55 to 65 Si, and small amounts of Bi and Sb are calculated as wB (%).
9. The spheroidizing inoculation method according to claim 5, wherein the stream inoculation device comprises a stream following funnel and two connecting rods 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 parallel to a cross beam above a suspension arm of the spheroidizing bag; the outer side of the suspension arm is provided with a vertical slideway, a sliding block is arranged on the slideway, an electric push rod is arranged on the sliding block, and the output end of the electric push rod is connected with the end part of the connecting rod; the lower extreme exit of flow-following funnel is equipped with the stopper, be connected with the stay cord on the stopper, flow-following funnel with the wiring groove has been seted up respectively to the surface of connecting rod, the stay cord is followed the wiring groove is led to the outside of balling package.
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| CN114790501B (en) * | 2022-05-20 | 2024-03-12 | 武汉武重铸锻有限公司 | Preparation method of large-tonnage ductile iron casting |
| CN115255294B (en) * | 2022-06-13 | 2023-08-15 | 天润工业技术股份有限公司 | Treatment process for producing high-strength high-toughness spheroidal graphite cast iron by using damp mould sand molding |
| 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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