CN115213360B - Preparation method of spheroidal graphite cast iron for hub of wind driven generator - Google Patents

Preparation method of spheroidal graphite cast iron for hub of wind driven generator Download PDF

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CN115213360B
CN115213360B CN202210533733.6A CN202210533733A CN115213360B CN 115213360 B CN115213360 B CN 115213360B CN 202210533733 A CN202210533733 A CN 202210533733A CN 115213360 B CN115213360 B CN 115213360B
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cast iron
ladle
hub
mass
spheroidal graphite
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CN115213360A (en
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赵伟龙
王惠兵
奚巧琴
赵益锋
张建中
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Ningbo Rixing Foundry Co ltd
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Ningbo Rixing Foundry Co ltd
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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D37/00—Controlling or regulating the pouring of molten metal from a casting melt-holding vessel
    • 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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • 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
    • 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
    • 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
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Abstract

The invention belongs to the field of cast iron casting, and relates to a preparation method of spheroidal graphite cast iron for a hub of a wind driven generator. The invention improves the traditional one-ladle molten iron pouring into 3-5-ladle different molten irons, not only ensures that the cast iron is solidified at the same time, effectively solves the shrinkage problem of the cast iron, saves raw materials and energy, reduces the adding amount of the nodulizer, reduces the time from the nodulizing to the pouring completion by 3-4min, and greatly reduces the upper plane scum in the pouring process, thereby reducing the use of slag remover and the labor intensity of slag skimming.

Description

Preparation method of spheroidal graphite cast iron for hub of wind driven generator
Technical Field
The invention belongs to the field of cast iron casting, and relates to a preparation method of spheroidal graphite cast iron for a hub of a wind driven generator.
Background
In recent years, the development of wind power generation is very rapid, the installed capacity of a wind power generator in China increases at a speed of 100% per year, and the domestic equipment capacity of wind power equipment is higher and higher, so that the wind power manufacturing process is continuously improved and perfected along with the expansion of the single machine capacity of the domestic wind power equipment and the scale of a wind power plant, and the mass production mature manufacturing process is essentially formed, wherein the main large-scale part hub is the very important part. The hub is an important part connecting the blades with the main shaft, and bears the thrust, torque, bending moment and gyroscopic moment of wind force acting on the blades. Because the high-strength spheroidal graphite cast iron has the advantages of irreplaceability, such as good casting performance, easy casting, good vibration damping performance, low stress concentration sensitivity and the like, the high-strength spheroidal graphite cast iron is used as the material of the hub in a large amount in the wind turbine generator system.
However, the existing spheroidal graphite cast iron consumes a large amount of energy and various raw materials in the preparation process, the prepared cast iron also has obvious shrinkage porosity problem, and the existing preparation process needs to strictly control harmful elements P and S in the raw materials, so that the cost in industrial production is greatly increased.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention provides a preparation method of spheroidal graphite cast iron for a hub of a wind driven generator, which is energy-saving, emission-reducing and solves the problem of shrinkage porosity of castings.
The aim of the invention can be achieved by the following technical scheme: a method of preparing spheroidal graphite cast iron for a hub of a wind turbine, the method comprising the steps of: smelting cast iron raw materials into molten iron, respectively pouring the molten iron into 3-5 ladles, adding a spheroidizing agent into each ladle, sequentially covering inoculant on the surface of the spheroidizing agent for spheroidizing inoculation, sequentially pouring the molten iron in the ladles into the same casting mould, and carrying out heat preservation treatment after pouring to obtain cast iron.
In the preparation method of the spheroidal graphite cast iron for the hub of the wind driven generator, the temperature of the molten iron in each ladle is reduced by 5-15 ℃ in sequence according to the casting sequence in the casting process, wherein the temperature of the first ladle is 1370-1380 ℃. After the first strand of molten iron enters the cavity, the first strand of molten iron is continuously contacted with the normal-temperature sand mold, the temperature difference is large, and the bottom pouring of the molten iron is raised, so that the molten iron is continuously cooled, the improvement of the temperature of the first ladle of molten iron is beneficial to ensuring the full combination of the first ladle of molten iron and the second ladle of molten iron, and the cold separation between the position and the upper plane can be avoided. Because the molten iron continuously transfers heat to and dissipates heat from the casting mold, the higher the temperature of the casting mold, the smaller the temperature difference between the newly-fed molten iron and the casting mold, the less the heat transferred, and the less the energy of the molten iron required, the invention needs to control the temperature of the molten iron in each ladle.
In the preparation method of the spheroidal graphite cast iron for the hub of the wind driven generator, the molten iron in the ladle is 13-39% of the total molten iron mass.
In the above-mentioned spheroidal graphite cast iron preparation method for a wind turbine hub, the spheroidizing agent addition amount is 0.8-0.9% of the mass of molten iron in each ladle, wherein the mass percentage of the first ladle spheroidizing agent addition < the mass percentage of the second ladle spheroidizing agent addition = the mass percentage of the remaining ladle spheroidizing agent addition.
Preferably, the addition amount of the first ladle spheroidizing agent is 0.8% of the mass of the first ladle, and the addition amount of the rest spheroidizing agents accounts for 0.9% of the mass of the molten iron in each ladle.
The invention not only reduces the adding amount of the nodulizer and reduces the cost, but also can reduce the nodulizing waiting time, thereby reducing the burning loss and greatly reducing the tendency of nodulizing decline; the ladle is reduced, so that the molten iron has more complete reaction and better spheroidization effect. Because the using amount of the nodulizer is reduced, the generation of the spheroidized slag is reduced, the using amount of the slag remover is reduced, and the labor intensity in the slag skimming process is reduced.
In the preparation method of the spheroidal graphite cast iron for the hub of the wind driven generator, the spheroidizing agent comprises the following components in percentage by mass: 3-12wt% of Mg, 0.2-2wt% of Re, 30-45wt% of Si, 0.6-2wt% of Ca, 0.2-1wt% of Ba, 0-1wt% of Al, 0-0.5wt% of Ti and 0-0.5wt% of MgO.
In the preparation method of the spheroidal graphite cast iron for the hub of the wind driven generator, the total addition amount of the inoculant covered on the surface of the nodulizer is 0.2-0.35% of the mass of molten iron.
In the preparation method of the spheroidal graphite cast iron for the hub of the wind driven generator, inoculant with the mass of 0.2 percent of molten iron is added along with the flow in the casting process.
In the preparation method of the spheroidal graphite cast iron for the hub of the wind driven generator, the grain diameter of the inoculant is 0.2-0.7mm, and the components comprise, by mass: 60-80wt% Si, 0-1wt% Al, 1-2wt% Ca, 1-2wt% Ba, 0.1-0.3wt% Bi.
In the preparation method of the spheroidal graphite cast iron for the hub of the wind driven generator, the spheroidal graphite cast iron comprises the following elements in percentage by mass: 3.80 to 3.95 weight percent of C, 1.19 to 1.39 weight percent of Si, less than or equal to 0.20 weight percent of Mn, less than or equal to 0.050 weight percent of P, less than or equal to 0.015 weight percent of S, 0.030 to 0.045 weight percent of Mg, less than or equal to 0.019 weight percent of Re, less than or equal to 0.005 weight percent of Sb, 0.20 to 0.40 weight percent of Cu, 0.10 to 0.60 weight percent of Ni, 0.020 to 0.080 weight percent of Sn, and the balance of Fe.
In the preparation method of the spheroidal graphite cast iron for the hub of the wind driven generator, the thickness of the casting mould is 65-360mm. The special pouring cup is used in the pouring process, the size is 1300mm multiplied by 400mm multiplied by 1000mm (height), and the molten iron conversion should be carried out between the distance of the residual molten iron in the pouring cup and the bottom 500mm-700 mm. The too low liquid level of the molten iron can cause scum to flow into the casting, the ladle replacement process requires time, and the problem that the residual molten iron in the pouring cup is more than 700mm away from the liquid level at the bottom is avoided.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention improves the traditional one-ladle molten iron pouring into 3-5-ladle different molten iron pouring, so that the whole spheroidal graphite cast iron tends to be solidified at the same time, the problem of shrinkage porosity of the cast iron is effectively solved, and the raw materials and energy are saved.
2. According to the invention, the adding amount of the nodulizer is reduced by improving the casting process of 3-5 packs of different molten irons, the nodulizing waiting time is correspondingly reduced, the upper plane scum in the casting process is greatly reduced, the use of the slag remover is reduced, and the slag removing labor intensity is reduced.
3. The invention has good spheroidizing and inoculating effects because of subpackaging treatment, and the time for completing casting at intervals after spheroidizing and inoculating is shorter (the time is reduced to 9 minutes from 12 minutes of conventional one-time casting), the component percentage P of harmful elements can be widened from 0.040% to 0.050%, the content of the original components is improved by 25%, S can be widened from 0.01% to 0.015%, the content of the original components is improved by 50%, the standard of the content of the harmful elements is widened, namely, the original auxiliary material with higher content P/S can be used, the invention has great benefit for saving the cost of raw materials, and the alkalinity requirement of the smelting process on the furnace lining of an electric furnace can be reduced.
Drawings
FIG. 1 is a golden phase diagram of cast iron prepared in example 1.
FIG. 2 is a golden phase diagram of cast iron prepared in example 1 after corrosion test.
FIG. 3 is a golden phase diagram of cast iron prepared in example 2.
FIG. 4 is a golden phase diagram of cast iron prepared in example 2 after corrosion testing.
FIG. 5 is a golden phase diagram of cast iron prepared in example 3.
FIG. 6 is a golden phase diagram of cast iron prepared in example 3 after corrosion testing.
FIG. 7 is a golden phase diagram of cast iron prepared in example 4.
FIG. 8 is a golden phase diagram of cast iron prepared in example 4 after corrosion testing.
FIG. 9 is a golden phase diagram of cast iron prepared in example 5.
FIG. 10 is a golden phase diagram of cast iron prepared in example 5 after corrosion testing.
FIG. 11 is a golden phase diagram of cast iron prepared in comparative example 1.
FIG. 12 is a golden phase diagram of cast iron prepared in comparative example 1 after corrosion test.
Detailed Description
The following are specific examples of the present invention, and the technical solutions of the present invention are further described, but the present invention is not limited to these examples.
Raw material selection: 14 parts of high-purity pig iron, 2.9 parts of high-quality scrap steel and 0.2 part of ferrosilicon;
the high-purity pig iron comprises the following components in percentage by mass: 3.10% C, 1.82% Si, 0.421% Mn, 0.015% P, 0.010% Cr, 0.008% Cu, 0.005% Ti, 0.004% V, 0.0001% Mo, 0.0011% Pb, 0.0009% B, 0.0006% Sn, 0.0007% Bi, and the balance Fe.
The high-quality scrap steel comprises the following components in percentage by mass: less than or equal to 0.52wt% of C, less than or equal to 1.1wt% of Mn, less than or equal to 0.040wt% of Cr, less than or equal to 0.040wt% of S, and the balance of Fe.
The ferrosilicon comprises the following components in percentage by mass: 53wt% Si, 1.18wt% Al, 0.47wt% Mn, 0.53wt% Cr, the balance being Fe.
Example 1
S1, placing high-purity pig iron, high-quality scrap steel, a furnace return material, a carburant and ferrosilicon into a smelting furnace for smelting, controlling the tapping temperature of molten iron to 1480 ℃, dividing 23000Kg of molten iron into 4 ladles, and sequentially obtaining the masses of the ladles of 5000Kg, 8000Kg, 6000Kg and 4000Kg.
S2, adding a nodulizer into each ladle, wherein the adding amount of the nodulizer is 45Kg, 64Kg, 48Kg and 32Kg in sequence, and the nodulizer comprises the following components in percentage by mass: 6.1wt% Mg, 0.8wt% Re, 32wt% Si, 0.91wt% Ca, 0.40wt% Ba, 0.63wt% Al, 0.08wt% Ti, 0.39wt% MgO.
S3, covering inoculants accounting for 0.3% of the total molten iron mass on the surface of each ladle nodulizer, and performing nodulizing inoculation at 1450 ℃; the inoculant has the particle size of 0.5mm and comprises the following components in percentage by mass: 72wt% Si, 0.56wt% Al, 1.5wt% Ca, 0.52wt% Ba, 0.27wt% Bi.
S4, pouring molten iron in a ladle into a casting mold sequentially after spheroidizing inoculation, adding inoculant along with flow in the pouring process, wherein the connected test block casting mold is of a resin sand molding and bottom pouring gate filling type, the pouring sequence is that 5000Kg is poured at 1375 ℃, the pouring time is 67s+420s=487s after spheroidizing, 8000Kg is poured at 1360 ℃, the pouring time is 107s+420s=527S after spheroidizing, 6000Kg is poured at 1355 ℃, the pouring time is 80s+420s=500S after spheroidizing, 4000Kg is poured at 1350 ℃, the pouring time is 53s+420s=473S after spheroidizing, so the maximum spheroidizing time is 527S, and the average wall thickness of the final casting mold is 176mm.
S5, after pouring, preserving heat in the casting mould, cooling to 300 ℃, and taking out the casting from the casting mould;
the final cast iron comprises the following components in percentage by mass: 3.82wt% C, 1.20wt% Si, 0.06wt% Mn, 0.012wt% P, 0.010wt% S, 0.040wt% Mg, 0.009wt% Re, 0.001wt% Sb,0.25wt% Cu, 0.56wt% Ni, 0.029wt% Sn, and the balance being Fe.
Example 2:
s1, placing high-purity pig iron, high-quality scrap steel, a furnace return material, a carburant and ferrosilicon into a smelting furnace for smelting, controlling the tapping temperature of molten iron to 1480 ℃, dividing 23000Kg of molten iron into 3 ladles, and sequentially obtaining the mass of the ladles to 6000Kg, 9000Kg and 8000Kg.
S2, adding a nodulizer into each ladle, wherein the adding amount of the nodulizer is 48Kg, 81Kg and 72Kg in sequence, and the nodulizer comprises the following components in percentage by mass: 6.1wt% Mg, 0.8wt% Re, 32wt% Si, 0.91wt% Ca, 0.40wt% Ba, 0.63wt% Al, 0.08wt% Ti, 0.39wt% MgO.
S3, covering inoculants accounting for 0.3% of the total molten iron mass on the surface of each ladle nodulizer, and performing nodulizing inoculation at 1450 ℃; the inoculant has the particle size of 0.5mm and comprises the following components in percentage by mass: 72wt% Si, 0.56wt% Al, 1.5wt% Ca, 0.52wt% Ba, 0.27wt% Bi.
S4, pouring molten iron in a ladle into a casting mold sequentially after spheroidizing inoculation, adding inoculant along with flow in the pouring process, wherein the casting mold of the conjoined test block is in a resin sand molding shape, and is in a bottom pouring gate filling shape, wherein the pouring sequence is that 6000Kg is poured at 1375 ℃, the time from the spheroidization is 80s+420s=500S, 9000Kg is poured at 1360 ℃, the time from the spheroidization is 120s+420s=540S, 8000Kg is poured at 1355 ℃, and the time from the spheroidization is 107s+420s=527S, so that the time from the longest spheroidization is 540S, and the average wall thickness of the final casting mold is 176mm.
And S5, after pouring, preserving heat in the casting mould, cooling to 300 ℃, and taking out the casting from the casting mould.
Example 3:
s1, placing high-purity pig iron, high-quality scrap steel, a furnace return material, a carburant and ferrosilicon into a smelting furnace for smelting, controlling the tapping temperature of molten iron to 1480 ℃, dividing 23000Kg of molten iron into 5 ladles, and sequentially obtaining the masses of the ladles of 5000Kg, 3000Kg, 4000Kg, 5000Kg and 6000Kg.
S2, adding a nodulizer into each ladle, wherein the adding amount of the nodulizer is 40Kg, 27Kg, 36Kg, 45Kg and 54Kg in sequence, and the nodulizer comprises the following components in percentage by mass: 6.1wt% Mg, 0.8wt% Re, 32wt% Si, 0.91wt% Ca, 0.40wt% Ba, 0.63wt% Al, 0.08wt% Ti, 0.39wt% MgO.
S3, covering inoculants accounting for 0.3% of the total molten iron mass on the surface of each ladle nodulizer, and performing nodulizing inoculation at 1450 ℃; the inoculant has the particle size of 0.5mm and comprises the following components in percentage by mass: 72wt% Si, 0.56wt% Al, 1.5wt% Ca, 0.52wt% Ba, 0.27wt% Bi.
S4, pouring molten iron in a ladle into a casting mold sequentially after spheroidizing inoculation, adding inoculant along with flow in the pouring process, wherein the casting mold of the conjoined test block is in a resin sand molding and bottom pouring gate filling type, wherein the pouring sequence is that 5000Kg is poured at 1375 ℃, the time from the spheroidizing to the pouring completion is 67s+420s=487s, 3000Kg is poured at 1360 ℃, the time from the spheroidizing to the pouring completion is 40s+420s=26s, 4000Kg is poured at 1355 ℃, the time from the spheroidizing to the pouring completion is 53s+420s=4737s, 5000Kg is poured at 1350 ℃, the time from the spheroidizing to the pouring completion is 47s+420s=487s, 6000Kg is poured at 1345 ℃, the time from the spheroidizing to the pouring completion is 80s+420s=500S, so that the average wall thickness of the final casting mold is 176mm.
And S5, after pouring, preserving heat in the casting mould, cooling to 300 ℃, and taking out the casting from the casting mould.
Example 4:
the only difference from example 1 is that the casting sequence in step S4 is 5000Kg at 1375 ℃, 8000Kg at 1375 ℃, 6000Kg at 1375 ℃ and 4000Kg at 1375 ℃.
Example 5:
the difference from example 1 was only that the spheroidizing agent added amount was 1.0% of the spheroidizing agent added amount per ladle mass.
Comparative example 1:
s1, placing high-purity pig iron, high-quality scrap steel, a furnace return material, a carburant and ferrosilicon into a smelting furnace for smelting, controlling the tapping temperature of molten iron to 1480 ℃, and dividing 23000Kg of molten iron into 1 ladle.
S2, adding 230Kg of nodulizer into the ladle, wherein the nodulizer comprises the following components in percentage by mass: 6.1wt% Mg, 0.8wt% Re, 32wt% Si, 0.91wt% Ca, 0.40wt% Ba, 0.63wt% Al, 0.08wt% Ti, 0.39wt% MgO.
S3, covering inoculants accounting for 0.3% of the total molten iron mass on the surface of each ladle nodulizer, and performing nodulizing inoculation at 1450 ℃; the inoculant has the particle size of 0.5mm and comprises the following components in percentage by mass: 72wt% Si, 0.56wt% Al, 1.5wt% Ca, 0.52wt% Ba, 0.27wt% Bi.
S4, pouring molten iron in a ladle into a casting mold sequentially after spheroidizing inoculation, adding inoculant along with flow in the pouring process, wherein the connected test block casting mold is of a resin sand molding, and filling a bottom pouring runner, wherein the pouring temperature is 1365 ℃, and the time from the spheroidization to the pouring completion is 307 s+420s=727s, so that the average wall thickness of the final casting mold is 176mm after the longest spheroidization to the pouring completion is 727S.
And S5, after pouring, preserving heat in the casting mould, cooling to 300 ℃, and taking out the casting from the casting mould.
Table 1: mechanical properties of cast iron prepared in examples 1-2 and comparative examples 1-4 were examined
Corrosion test: after the sample is ground and polished to a mirror surface (namely Ra is less than or equal to 0.04), the surface is washed twice by alcohol and dried by a blower, then 4% nitrate alcohol solution is dripped on the surface, the surface is corroded for 6-35 seconds (the surface is darkened), and then the surface is washed by clear water and dried by the blower. And placing the sample on a metallographic microscope for observation.
FIG. 1 is a golden phase diagram of cast iron prepared in example 1; FIG. 2 is a golden phase diagram of cast iron prepared in example 1 after corrosion test. From the graph, the spheroidal graphite has good spheroidal graphite effect, spheroidization grade 2 grade graphite has 7 grade, the ferrite content of the matrix is more than or equal to 95 percent, and the physicochemical property is excellent.
FIG. 3 is a golden phase diagram of cast iron prepared in example 2; FIG. 4 is a golden phase diagram of cast iron prepared in example 2 after corrosion testing. From the graph, the graphite spheroid has good effect, spheroid grade 2 grade graphite has 7 grade, matrix ferrite content is more than or equal to 95%, physical and chemical properties are good, and other indexes except yield strength are slightly lower than those of the example 1.
FIG. 5 is a golden phase diagram of cast iron prepared in example 3; FIG. 6 is a golden phase diagram of cast iron prepared in example 3 after corrosion testing. From the graph, the spheroidal graphite has good spheroidal graphite effect, spheroidization grade 2 grade graphite has 7 grade, the ferrite content of the matrix is more than or equal to 95 percent, the physicochemical properties are excellent, and the physicochemical property indexes are basically consistent with those of the embodiment 1.
FIG. 7 is a golden phase diagram of cast iron prepared in example 4; FIG. 8 is a golden phase diagram of cast iron prepared in example 4 after corrosion testing. From the graph, the spheroidal graphite has good spheroidal graphite effect, spheroidization grade 2 grade graphite has a size of 7 grade, the ferrite content of the matrix is more than or equal to 95 percent, and the physicochemical index is lower than that of the embodiment 1.
FIG. 9 is a golden phase diagram of cast iron prepared in example 5; FIG. 10 is a golden phase diagram of cast iron prepared in example 5 after corrosion testing. From the graph, the spheroidization effect is good, the spheroidization grade 2 grade graphite is 7 grade in size, the ferrite content of the matrix is more than or equal to 95%, and the physical and chemical properties are not obviously improved compared with those of the example 1 (the tensile strength and the hardness are reduced, the yield strength is unchanged, and the impact energy average value at minus 40 ℃ is improved).
FIG. 11 is a golden phase diagram of cast iron prepared in comparative example 1; FIG. 12 is a golden phase diagram of cast iron prepared in comparative example 1 after corrosion test. As shown in the figure, the spheroidization effect is general, the spheroidization grade 2 grade graphite has a size of 6 grade, the ferrite content of the matrix is more than or equal to 90 percent, and the physical and chemical properties are obviously reduced compared with those of the example 1.
In conclusion, the invention improves the traditional one-ladle molten iron pouring into 3-5-ladle different molten iron pouring, so that the cast iron is solidified at the same time, the problem of shrinkage porosity of the cast iron is effectively solved, the performance of the cast iron is improved, and the raw materials and energy are saved. According to the invention, the adding amount of the spheroidizing agent is reduced by improving the casting process of 3-5 packs of different molten irons, the time from the spheroidizing process to the casting process is correspondingly reduced from 727S to 527S, and the upper plane scum in the casting process is also greatly reduced, so that the use of slag remover is reduced, and the slag removing labor intensity is reduced.
The point values in the technical scope of the present invention are not exhaustive, and the new technical solutions formed by equivalent substitution of single or multiple technical features in the technical solutions of the embodiments are also within the scope of the present invention; meanwhile, in all the listed or unrecited embodiments of the present invention, each parameter in the same embodiment represents only one example of the technical scheme (i.e. a feasibility scheme), and no strict coordination and limitation relation exists between each parameter, wherein each parameter can be replaced with each other without violating axiom and the requirement of the present invention, except what is specifically stated.
The technical means disclosed by the scheme of the invention is not limited to the technical means disclosed by the technical means, and also comprises the technical scheme formed by any combination of the technical features. While the foregoing is directed to embodiments of the present invention, it will be appreciated by those skilled in the art that changes and modifications may be made without departing from the principles of the invention, and such changes and modifications are intended to be included within the scope of the invention.
The specific embodiments described herein are offered by way of example only to illustrate the spirit of the invention. Those skilled in the art may make various modifications or additions to the described embodiments or substitutions thereof without departing from the spirit of the invention or exceeding the scope of the invention as defined in the accompanying claims.

Claims (8)

1. A method for preparing spheroidal graphite cast iron for a hub of a wind driven generator, the method comprising the steps of: smelting cast iron raw materials into molten iron, respectively pouring the molten iron into 3-5 ladles, adding a spheroidizing agent into each ladle, sequentially covering inoculant on the surface of the spheroidizing agent for spheroidizing inoculation, sequentially pouring the molten iron in the ladles into the same casting mould, and carrying out heat preservation treatment after pouring to obtain castings;
in the casting process, the temperature of the iron water in each ladle is reduced by 5-15 ℃ in sequence according to the casting sequence, wherein the temperature of the first ladle is 1370-1380 ℃;
the spheroidizing agent is added in an amount of 0.8-0.9% of the mass of molten iron in each ladle, wherein the mass percent of the first ladle spheroidizing agent added is less than the mass percent of the second ladle spheroidizing agent added = the mass percent of the rest ladle spheroidizing agent added.
2. A method of manufacturing spheroidal graphite cast iron for a hub of a wind power generator according to claim 1 wherein the molten iron in each ladle is 13-39% of the total molten iron mass.
3. The method for manufacturing spheroidal graphite cast iron for a hub of a wind power generator according to claim 1, wherein the spheroidizing agent comprises the following components in mass percent: 3-12wt% of Mg, 0.2-2wt% of Re, 30-45wt% of Si, 0.6-2wt% of Ca, 0.2-1wt% of Ba, 0-1wt% of Al, 0-0.5wt% of Ti and 0-0.5wt% of MgO.
4. The method of claim 1, wherein the total inoculant added to the nodulizer surface coating is 0.2-0.35% of the molten iron mass in each ladle.
5. The method for manufacturing spheroidal graphite cast iron for a hub of a wind power generator according to claim 1, wherein the inoculant is added in an amount of 0.2% by mass of molten iron along with the flow during the casting process.
6. The method for preparing spheroidal graphite cast iron for a hub of a wind driven generator according to claim 1 or 4, wherein the inoculant has a particle size of 0.2-0.7mm, and comprises the following components in percentage by mass: 60-80wt% Si, 0-1wt% Al, 1-2wt% Ca, 1-2wt% Ba, 0.1-0.3wt% Bi.
7. The method for preparing spheroidal graphite cast iron for a hub of a wind driven generator according to claim 1, wherein the cast iron comprises the following elements in percentage by mass: 3.80-3.95 wt% of C, 1.19-1.39 wt% of Si, less than or equal to 0.20wt% of Mn, less than or equal to 0.050wt% of P, less than or equal to 0.015wt% of S, 0.030-0.045 wt% of Mg, less than or equal to 0.019wt% of Re, less than or equal to 0.005wt% of Sb, 0.20-0.40 wt% of Cu, 0.10-0.60 wt% of Ni, 0.020-0.080 wt% of Sn, and the balance of Fe.
8. The method for producing spheroidal graphite cast iron for a hub of a wind power generator according to claim 1, wherein the thickness of the casting mold is 65-360mm.
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CN103924039A (en) * 2014-04-30 2014-07-16 江苏大峘集团有限公司 Rotary multi-station hot metal pretreatment system and method
CN105385802A (en) * 2015-12-03 2016-03-09 河北裕龙铸造有限公司 Casting technique for low-temperature high-tenacity nodular cast iron butterfly valve body
CN206706174U (en) * 2017-05-19 2017-12-05 三祥新材（宁夏）有限公司 A kind of double-contracting lid spheroidising station
CN109702153A (en) * 2019-01-25 2019-05-03 宁波日星铸业有限公司 Wind-power spherulitic graphite cast iron wheel hub is poured control method and improves technique

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1126633A (en) * 1964-10-23 1968-09-11 Benteler Geb Paderwerk Continuous metal casting equipment
JPH1190616A (en) * 1997-09-17 1999-04-06 Higashio Mec Kk Automatic molten metal pouring device
JP2002003909A (en) * 2000-06-26 2002-01-09 Nkk Corp Distribution system for molten iron and method for controlling distribution of molten iron
RU2464124C1 (en) * 2011-08-08 2012-10-20 Открытое акционерное общество "ИНЖЕНЕРНЫЙ ЦЕНТР ЯДЕРНЫХ КОНТЕЙНЕРОВ" Method of rotary casting of multilayer billets for shipping packages (sp) for waste nuclear fuel from high-strength iron with ball-shape graphite, and sp case one-piece casting thus produced
CN103924039A (en) * 2014-04-30 2014-07-16 江苏大峘集团有限公司 Rotary multi-station hot metal pretreatment system and method
CN105385802A (en) * 2015-12-03 2016-03-09 河北裕龙铸造有限公司 Casting technique for low-temperature high-tenacity nodular cast iron butterfly valve body
CN206706174U (en) * 2017-05-19 2017-12-05 三祥新材（宁夏）有限公司 A kind of double-contracting lid spheroidising station
CN109702153A (en) * 2019-01-25 2019-05-03 宁波日星铸业有限公司 Wind-power spherulitic graphite cast iron wheel hub is poured control method and improves technique

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