CN115927949B - Preparation method of vermicular graphite cast iron with high-spheroidization graphite structure in inner cavity - Google Patents
Preparation method of vermicular graphite cast iron with high-spheroidization graphite structure in inner cavity Download PDFInfo
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- CN115927949B CN115927949B CN202211608726.4A CN202211608726A CN115927949B CN 115927949 B CN115927949 B CN 115927949B CN 202211608726 A CN202211608726 A CN 202211608726A CN 115927949 B CN115927949 B CN 115927949B
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 78
- 229910001018 Cast iron Inorganic materials 0.000 title claims abstract description 76
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 229910002804 graphite Inorganic materials 0.000 title abstract description 46
- 239000010439 graphite Substances 0.000 title abstract description 46
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 116
- 229910052742 iron Inorganic materials 0.000 claims abstract description 54
- 239000002054 inoculum Substances 0.000 claims abstract description 49
- 238000003723 Smelting Methods 0.000 claims abstract description 17
- 238000001816 cooling Methods 0.000 claims abstract description 16
- 239000002994 raw material Substances 0.000 claims abstract description 15
- 239000012535 impurity Substances 0.000 claims abstract description 14
- 238000000137 annealing Methods 0.000 claims abstract description 5
- 238000005303 weighing Methods 0.000 claims abstract description 3
- 238000011081 inoculation Methods 0.000 claims description 26
- 238000005266 casting Methods 0.000 claims description 21
- 238000000034 method Methods 0.000 claims description 16
- 239000011521 glass Substances 0.000 claims description 9
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 6
- 229910052717 sulfur Inorganic materials 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 5
- 229910052749 magnesium Inorganic materials 0.000 claims description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 229910052720 vanadium Inorganic materials 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 2
- 238000000465 moulding Methods 0.000 claims description 2
- 230000002035 prolonged effect Effects 0.000 abstract description 4
- 230000000052 comparative effect Effects 0.000 description 20
- 239000013078 crystal Substances 0.000 description 10
- 239000000463 material Substances 0.000 description 10
- 229910052799 carbon Inorganic materials 0.000 description 7
- 239000003795 chemical substances by application Substances 0.000 description 5
- 239000011777 magnesium Substances 0.000 description 5
- 230000007704 transition Effects 0.000 description 5
- 230000007547 defect Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 3
- 229910001060 Gray iron Inorganic materials 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000004090 dissolution Methods 0.000 description 3
- 230000005496 eutectics Effects 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 230000035882 stress Effects 0.000 description 3
- 238000004781 supercooling Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 229910001141 Ductile iron Inorganic materials 0.000 description 2
- 229910000616 Ferromanganese Inorganic materials 0.000 description 2
- 229910001309 Ferromolybdenum Inorganic materials 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 229910000805 Pig iron Inorganic materials 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- -1 furnace returns Inorganic materials 0.000 description 2
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 150000002910 rare earth metals Chemical class 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- 210000002268 wool Anatomy 0.000 description 2
- 229910052580 B4C Inorganic materials 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- INAHAJYZKVIDIZ-UHFFFAOYSA-N boron carbide Chemical compound B12B3B4C32B41 INAHAJYZKVIDIZ-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000006355 external stress Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- HLXZNVUGXRDIFK-UHFFFAOYSA-N nickel titanium Chemical compound [Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni] HLXZNVUGXRDIFK-UHFFFAOYSA-N 0.000 description 1
- 229910001000 nickel titanium Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 229910052702 rhenium Inorganic materials 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 125000004434 sulfur atom Chemical group 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The application relates to the technical field of cast iron, in particular to a preparation method of vermicular cast iron with a high spheroidization graphite structure in an inner cavity, which comprises the following steps of smelting: weighing raw materials, and smelting the raw materials into molten iron; inoculating: pouring the molten iron into a ladle, and adding a vermiculizer and an inoculant into the ladle; the vermiculizer comprises the following components: si:42-48wt%, ca:2.0-2.5wt%, al 0.5-1wt%, re:5.5-6.5wt%, mg:5.0 to 6.0wt% of Fe and unavoidable impurities in balance; the adding amount of the vermiculizer is 0.6-0.8wt% of the molten iron; the inoculant comprises the following components: si:70-75wt%, ce:1.5-2wt%, ca:0.75-1.25wt% of Al, 0.75-1.25wt% of Fe and unavoidable impurities in balance; pouring: pouring the inoculated molten iron, and annealing and cooling after pouring is finished. According to the application, through vermiculizer discharge of molten iron, graphite in the inner cavity of vermicular cast iron is spherical graphite, and vermicular graphite is arranged outside, so that the heat-conducting property is good, and the service life of the die is prolonged.
Description
Technical Field
The application relates to the technical field of cast iron, in particular to a preparation method of vermicular graphite cast iron with a graphite structure with a high spheroidization rate in an inner cavity.
Background
The metal mold used in industry at present is mainly a glass mold or a steel ingot mold, and the working condition is that the metal mold is subjected to the repeated circulation of high-temperature melt, the inner surface of the metal mold is in a periodical high-temperature thermal impact state, and the temperature difference between the inside and the outside is large. Therefore, the damage of the mold is mainly that the surface is oxidized and grown to reduce the dimensional accuracy and peel off to discard the mold, or that the heat conductivity is insufficient to cause the internal and external stresses of the mold to be larger to generate cracks to discard the mold.
The materials used in the prior glass mold are single spheroidal graphite cast iron, vermicular graphite cast iron and D-shaped graphite gray cast iron. The vermicular cast iron is cast iron with vermicular graphite and small amount of pellet, and the graphite is between the flaky graphite of gray iron and the spherical graphite of spheroidal iron, so that the vermicular cast iron has the performance between that of nodular cast iron and gray cast iron. In the prior art, the vermicular cast iron material is easy to have material toughness reduction and easy to have thermal fatigue failure, so that the service life of the vermicular cast iron material is reduced.
Therefore, improving the toughness, namely the heat conduction performance, of the vermicular graphite cast iron material has important significance for prolonging the service life of the glass die.
Disclosure of Invention
In order to improve the toughness of the vermicular cast iron, the application provides a preparation method of the vermicular cast iron with a graphite structure with a high spheroidization rate in an inner cavity.
In a first aspect, the application provides a preparation method of vermicular cast iron with a graphite structure with a high spheroidization rate in an inner cavity, which adopts the following technical scheme:
a preparation method of vermicular cast iron with a graphite structure with high spheroidization rate in an inner cavity comprises the following steps:
Smelting: weighing raw materials according to the following proportion ：C：3.50-3.65wt％,Si：2.50-2.80wt％,Mn：0.25-0.30wt％,Mo：0.15-0.25wt％,V：0.08-0.12wt％,Mg：0.015-0.019wt％,S≤0.03wt％,P≤0.04wt％,, wherein the balance of Fe and unavoidable impurities, and smelting the raw materials into molten iron;
Inoculating: pouring the molten iron into a ladle, and adding a vermiculizer and an inoculant into the ladle during pouring; the vermiculizer comprises the following components: si:42-48wt%, ca:2.0-2.5wt%, al 0.5-1wt%, re:5.5-6.5wt%, mg:5.0 to 6.0wt% of Fe and unavoidable impurities in balance; the adding amount of the vermiculizer is 0.6-0.8wt% of the molten iron; the inoculant comprises the following components: si:70-75wt%, ce:1.5-2wt%, ca:0.75-1.25wt% of Al, 0.75-1.25wt% of Fe and unavoidable impurities in balance;
Pouring: pouring the inoculated molten iron, and annealing and cooling the molten iron after pouring
By adopting the technical scheme, after the vermicular agent is added into the molten iron, elements such as rare earth and magnesium in the alloy firstly react with oxygen and sulfur in the molten iron, and desulfurization and deoxidation reactions occur in the molten iron, so that sulfur and oxygen are removed from the prism surface, and the interface energy on the basal surface is lower than the interface energy on the prism surface, so that spherical graphite or vermicular graphite is formed. Along with the increase of the adding amount of the vermicular agent, the content of residual rare earth and magnesium elements is gradually increased, which is sufficient for discharging the adsorption interference of oxygen and sulfur atoms on the edge surface, so that more and more graphite crystal nuclei selectively grow along the hexagonal basal surface in a radiation mode to form spherical graphite. According to the application, more vermiculizer is added to enable the molten iron to be subjected to excessive vermiculizer treatment, graphite forms of vermicular cast iron from the outer circle to the inner cavity are transited from vermicule to sphere, and the spheroidal graphite has higher strength, toughness and wear resistance, so that the plasticity and toughness of the vermiculized and inoculated cast iron are greatly improved. The preparation method improves the toughness, namely the heat conducting property, of the cast iron material, and prolongs the service life of the manufactured die.
Preferably, the smelting temperature is 1560-1600 ℃ during smelting.
By adopting the technical scheme, the smelting temperature is optimized, and the prepared vermicular cast iron is favorable to better performance.
Preferably, during inoculation, the vermiculizer is placed into a hanging bag, and the vermiculizer is covered by the inoculant.
By adopting the technical scheme, the inoculant is covered above the vermiculizer, so that the vermiculizer can be prevented from being oxidized and failed in advance.
Preferably, the inoculant is added in an amount of 0.3-0.7wt% of the molten iron during inoculation.
By adopting the technical scheme, the inoculant is dissolved in the molten iron to absorb heat so as to reduce the temperature of the molten iron in the surrounding area and provide enough supercooling conditions for forming graphite crystal nuclei; after dissolution, the inoculant forms a silicon-rich zone around, silicon being a graphitizing element which increases the activity of the carbon in the molten iron and promotes diffusion of the carbon. In the silicon-rich region, the carbon is in a supersaturated state, so that the carbon is more easily aggregated to form graphite crystal nuclei, which is equivalent to reducing the supercooling degree required by the formation of the graphite crystal nuclei and improving the number of the graphite crystal nuclei; the inoculant is gradually dissolved in molten iron, and a lot of tiny ferrosilicon particles remain after dissolution, and the particles suspend in the molten iron and serve as heterogeneous nucleus substrates formed by graphite nuclei, so that energy fluctuation required by graphite nuclei is greatly reduced, and supercooling degree of graphite nuclei is reduced. By optimizing the addition amount of the inoculant, the obtained vermicular cast iron has good fluidity, the shrinkage of the casting is reduced, the processing performance is better, the residual stress is reduced, and the mechanical property of the obtained cast iron is better.
Preferably, when the inoculating is carried out, the mass ratio of the vermiculizer to the inoculant is 1:1.
By adopting the technical scheme, the addition of the inoculant can promote the formation of eutectic crystal nuclei, each formed crystal nucleus independently grows in a liquid phase, and carbon elements are gathered from the liquid phase. As the number of crystal nuclei increases, the space distance between each crystal nucleus decreases, and the volume of liquid phase capable of providing carbon element for the growth of graphite nodules decreases, so that the growth speed of graphite nodules increases. Although the increase of the number of graphite cores increases the growth speed of the eutectic overall, the growth speed of single crystal nucleus is necessarily reduced, so that the graphite cores are more easily surrounded by an austenite shell to form spherical graphite, and the spherical graphite in an as-cast structure is increased, namely the vermicular rate is reduced; the vermiculizer and inoculant are added in a mass ratio optimized, so that the vermiculizer rate of the obtained vermicular cast iron reaches an ideal state.
Preferably, when the inoculation is performed, the inoculation temperature is 1530-1550 ℃ and the inoculation time is 2min.
By adopting the technical scheme, the inoculation temperature is too high, the time required for solidification of the molten iron is long, and inoculation decay is easy to occur; however, the inoculation temperature is too low, which is not beneficial to dissolution and absorption of inoculant and affects the fluidity of molten iron. The vermicular cast iron has better performance by optimizing the inoculation temperature and time.
Preferably, during pouring, inoculant is also added for stream inoculation, and the addition amount of the inoculant is 0.035-0.05wt% of the pouring liquid.
By adopting the technical scheme, the creep rate can be improved by secondary stream inoculation, and the vermicular cast iron casting with uniform chemical components, excellent mechanical properties and stable creep rate can be obtained.
Preferably, the casting temperature is 1390-1430 ℃ and the casting time is 5-7min.
By adopting the technical scheme, the higher the pouring temperature is, the more easily the defects of shrinkage cavity, shrinkage porosity, pit drawing and deformation are generated in the casting; and when the casting temperature is too low, the casting is easy to have defects of insufficient cast-in-situ, cold insulation and the like. Once a ladle of molten iron is poured for too long, the casting temperature of the ladle of molten iron is too high, and the casting temperature of the ladle of molten iron is too low; the molten iron in the early stage of casting is high in temperature, and high-temperature casting defects appear; and the casting at the later stage has a low-temperature pouring defect, so that the pouring time is controlled in the production process. Reasonable casting time is controlled so as to be beneficial to the quality of the inoculated vermicular cast iron. The longer the pouring time is, the more the inoculant in the vermicular cast iron and the vermicular and inoculating elements in the vermicular cast iron burn out, and the vermicular elements and inoculating elements of the vermicular cast iron also decay along with the lengthening of the pouring time. Therefore, the performance of the obtained vermicular cast iron is better by optimizing the temperature and time during casting.
Preferably, the concrete process of pouring is as follows: pouring the inoculated molten iron into a mould, forming a glass mould after pouring molding, taking out the molded glass mould from the mould, carrying out annealing treatment, heating the glass mould to 955-958 ℃, preserving heat for 10 hours, cooling to 425 ℃ along with a furnace, and discharging from the furnace for air cooling to normal temperature.
By adopting the technical scheme, pearlite in the matrix tissue of the material is removed, so that the material is in a state of almost no carbide.
In a second aspect, the application provides vermicular cast iron, which adopts the following technical scheme:
the vermicular cast iron is prepared by adopting the preparation method of the vermicular cast iron with the graphite structure with the inner cavity Gao Qiuhua.
By adopting the technical scheme, the metallographic structure formed by the obtained vermicular cast iron is a casting with the inner cavity spheroidizing reaching 90wt% and the outer circle vermiculizer more than 70wt%, so that the mechanical property of the cast iron is effectively improved, in particular the plasticity and toughness are improved, the surface finish is very high, the properties of wear resistance, heat resistance, corrosion resistance and oxidation resistance are high, the vermicular cast iron material has good heat conductivity and toughness, and the service life of the die of the vermicular cast iron material is prolonged.
In summary, the present application includes at least one of the following beneficial technical effects:
1. According to the application, more vermiculizer is added to enable molten iron to be subjected to transition vermiculizer treatment, the graphite form of the obtained vermicular cast iron is transited from the outer circle to the inner cavity from a worm shape to a ball shape, so that the graphite form of the working inner cavity of the die is spherical graphite with good oxidation resistance, the outer part is worm-shaped graphite with good heat conducting property, heat can be rapidly dissipated, the stress in the die is reduced, and the service life of the die is prolonged;
2. when the inoculant is inoculated, the inoculant is covered above the vermiculizer, so that the vermiculizer can be prevented from being oxidized and failed in advance;
3. According to the application, the vermiculizer and inoculant mass ratio is optimized during inoculation, so that the vermiculizer rate of the obtained vermicular cast iron is accurately controlled.
Drawings
FIG. 1 is a 100-fold metallographic photograph of the graphite morphology transition from the inner cavity to the outer edge of the vermicular cast iron of example 9 of the present application.
FIG. 2 is a 100-fold metallographic photograph of the graphite morphology transition from the inner cavity to the outer edge of the vermicular cast iron of comparative example 1 of the present application.
FIG. 3 is a 100-fold metallographic photograph of the graphite morphology transition from the inner cavity to the outer edge of the vermicular cast iron of comparative example 2 of the present application.
FIG. 4 is a 100-fold metallographic photograph of the graphite morphology transition from the inner cavity to the outer edge of the vermicular cast iron of comparative example 3 of the present application.
Detailed Description
The application is further illustrated by the following examples and figures 1-4.
Examples
Example 1
The embodiment discloses a preparation method of vermicular cast iron with a graphite structure with high spheroidization rate in an inner cavity, which comprises the following steps:
S1, batching: taking pig iron, scrap steel, furnace returns, ferromanganese, ferrosilicon and ferromolybdenum as raw materials; the raw materials comprise 3.50wt% of C, 2.50wt% of Si, 0.25wt% of Mn and Mo in the total raw materials: 0.15wt%, V:0.08wt%, mg:0.015wt%, S:0.03wt%, P:0.04wt% and the Fe (containing unavoidable impurities) is 93.435 wt%;
s2, smelting: placing the raw materials into a smelting furnace, heating to 1560 ℃, and controlling the smelting time to be 2min to obtain molten iron;
S3, inoculating: adding 3g of inoculant and 6g of vermiculizer into a hanging ladle, covering the inoculant above the vermiculizer, pouring 1000g of molten iron into the hanging ladle, and inoculating for 2min at the inoculation temperature of 1530 ℃;
Wherein: the inoculant comprises the following components: 70wt% of Si, 1.5wt% of Ce, 0.75wt% of Ca, 0.75wt% of Al, 27wt% of Fe (containing unavoidable impurities) and a particle diameter of 0.2 to 0.7mm, which are available from Ind, gonnon precision dies of Co., ltd; the vermiculizer comprises the following components: 42wt% Si, 2.0wt% Ca, 0.5wt% Al, 5.5wt% Re, 5.0wt% Mg, 45wt% Fe (containing unavoidable impurities) and a particle size of 5-20mm, available from the Nitinol precision dies Inc.
S4, pouring: pouring the inoculated molten iron into a mould, cooling the molten iron to obtain a blank, and controlling the pouring temperature to be 1410 ℃; taking out the obtained blank from the die, putting the blank into a withdrawal furnace, heating to 955 ℃, and preserving heat for 10 hours; and (3) cooling the annealed wool fitting to 425 ℃ along with a furnace, and discharging and air-cooling to obtain the vermicular graphite cast iron with the graphite structure with the high spheroidization rate in the inner cavity.
Example 2
This embodiment is substantially the same as embodiment 1 except that: in S3, the inoculant comprises the following components: 75wt% Si, 2wt% Ce, 1.25wt% Ca, 1.25wt% Al, and 20.5wt% Fe (containing unavoidable impurities).
Example 3
This embodiment is substantially the same as embodiment 1 except that: in S3, the vermiculizer comprises the following components: 48wt% of Si, 2.5wt% of Ca, 1wt% of Al, 6.5wt% of Re, 6.0wt% of Mg and 36wt% of Fe (containing unavoidable impurities). A step of
Example 4
This embodiment is substantially the same as embodiment 1 except that: and S4, adding 0.35g of inoculant into 1000g of molten iron after inoculation, injecting the mixture into a mold along with molten iron flow, and cooling to obtain a blank.
Example 5
This embodiment is substantially the same as embodiment 1 except that: and S4, adding 0.4g of inoculant into 1000g of molten iron after inoculation, and injecting the mixture into a mold along with molten iron flow, and cooling to obtain a blank.
Example 6
This embodiment is substantially the same as embodiment 1 except that: and S4, adding 0.5g of inoculant into 1000g of molten iron after inoculation, injecting the mixture into a mold along with molten iron flow, and cooling to obtain a blank.
Example 7
This embodiment is substantially the same as embodiment 5 except that: in S3, the addition amount of the inoculant is 4g.
Example 8
This embodiment is substantially the same as embodiment 5 except that: in S3, the addition amount of the inoculant is 5g.
Example 9
This embodiment is substantially the same as embodiment 5 except that: in S3, the addition amount of the inoculant is 6g.
Example 10
This embodiment is substantially the same as embodiment 5 except that: in S3, the addition amount of the inoculant is 7g.
Example 11
This embodiment is substantially the same as embodiment 9 except that: in S3, the adding amount of the vermiculizer is 7g.
Example 12
This embodiment is substantially the same as embodiment 9 except that: in S3, the adding amount of the vermiculizer is 8g.
Example 13
This embodiment is substantially the same as embodiment 9 except that: the preparation method has different proportions of vermicular graphite cast iron raw materials and different technological parameters.
The method comprises the following steps: a preparation method of vermicular cast iron with a graphite structure with high spheroidization rate in an inner cavity comprises the following steps:
S1, batching: taking pig iron, scrap steel, furnace returns, ferromanganese, ferrosilicon and ferromolybdenum as raw materials; the raw materials comprise 3.65wt% of C, 2.80wt% of Si, 0.30wt% of Mn and Mo in the total raw materials: 0.25wt%, V:0.12wt%, mg:0.019wt%, S:0.02wt%, P:0.03 weight percent of Fe (containing unavoidable impurities) and 92.811 weight percent of the alloy;
S2, smelting: placing the raw materials into a smelting furnace, heating to 1600 ℃, and controlling the smelting time to be 2min to obtain molten iron;
s3, inoculating: adding 6g of inoculant and 6g of vermiculizer into a hanging ladle, covering the inoculant above the vermiculizer, pouring 1000g of molten iron into the hanging ladle, and inoculating for 2min at 1550 ℃;
S4, pouring: adding 0.4g inoculant into 1000g molten iron after inoculation, injecting the mixture into a mold along with molten iron flow, and cooling to obtain a blank, wherein the casting temperature is controlled to be 1430 ℃; taking out the obtained blank from the die, putting the blank into a withdrawal furnace, heating to 958 ℃, and preserving heat for 10 hours; and (3) cooling the annealed wool fitting to 425 ℃ along with a furnace, and discharging and air-cooling to obtain the vermicular graphite cast iron with the graphite structure with the high spheroidization rate in the inner cavity.
Comparative example
Comparative example 1
This comparative example differs from example 9 in that in S3, the amount of vermiculizer added was 5g.
Comparative example 2
This comparative example differs from example 9 in that in S3, the amount of vermiculizer added was 10g.
Comparative example 3
This comparative example differs from example 9 in that in S4 the casting temperature is 1350 ℃.
Performance detection
1. The vermicular cast iron prepared in each example and each comparative example was tested for tensile strength by GB/T228.1-2010 Metal Material room temperature tensile test method, recorded as data B, and the test results are recorded in Table 1.
2. After 10 ten thousand times of use, the vermicular cast iron prepared in each example and each comparative example was subjected to tensile strength measurement by GB/T228.1-2010 Metal Material room temperature tensile test method, recorded as data B, and the test results are recorded in Table 1.
3. The number of times of use of the vermicular cast iron prepared in each example and each comparative example when scrapped was measured, recorded as data C, and the test results were recorded in table 1.
4. The vermicular cast iron obtained in example 9 and comparative examples 1 to 3 was taken, a metallographic specimen was taken and polished with reference to GB/T9441-2009, and a photomicrograph (magnification 100) was taken with an optical microscope, as shown in FIGS. 1 to 4.
TABLE 1 Performance test data sheets for examples 1-13 and comparative examples 1-3
Referring to Table 1, in combination with examples 1-3, it can be seen that varying the ratio of inoculant components (example 2) or vermiculizer components (example 3) within the appropriate range yields vermiculized cast iron with better toughness and longer service life.
Referring to table 1, in combination with examples 1 and 4 to 6, it can be seen that the vermicular rate of vermicular cast iron can be improved by adding inoculant for secondary inoculation during pouring, and meanwhile, the obtained vermicular cast iron has better toughness and higher stability, so that the service life is improved to a certain extent.
Referring to Table 1, in combination with examples 5, 7-10, it can be seen that the addition of inoculant added during inoculation is varied within a suitable range, and the prepared vermicular cast iron has good toughness and longer service life; the addition of a certain amount of inoculant in the preparation process of vermicular cast iron can influence the distribution of graphite, refine eutectic cells, reduce the spacing between pearlite pieces, ensure that boron carbide is distributed in isolated small blocks, and improve the structure and performance of cast iron. With increasing inoculant levels, the tensile strength of the cast iron increases gradually, but when inoculant levels are increased, the tensile strength of the cast iron decreases significantly.
Referring to Table 1 in combination with FIGS. 1-3, it can be seen from comparative examples 9, 11 and 12 and comparative examples 1-2 that the amount of vermiculizer added is too small (comparative example 1), the molten iron is under-treated, the spheroidal graphite on the inner surface of vermicular cast iron is less, and most of vermicular graphite is present from the inner cavity to the outer edge; the vermicular agent is excessively added (comparative example 2), the molten iron is subjected to treatment, and the formed vermicular cast iron still has vermicular and spheroidal external graphite form, so that the aim of improving the heat conductivity cannot be achieved; when the vermicular agent is added in an appropriate amount, the mass ratio of the vermicular agent to the inoculant is 1:1 (example 9), and when the vermicular rate and the inoculation state are in a critical state, the graphite morphology of the inner cavity of the obtained vermicular cast iron is spherical graphite with good oxidation resistance; the exterior is vermicular graphite, the thermal conductivity is good, the heat can be rapidly dissipated, the stress in the vermicular graphite cast iron is reduced, and the service life of the die is prolonged.
Referring to table 1 in combination with fig. 1 and 4, it can be seen from comparative examples 9 and 4 that when the casting temperature is low, the carbon content of the formed vermicular cast iron is reduced, the golden phase diagram shows that graphite floats, the inner cavity and the outer circle of the vermicular cast iron are vermicular and spherical, the purpose of improving the heat conductivity is not achieved, and the service life of the die is reduced.
The present embodiment is only for explanation of the present application and is not to be construed as limiting the present application, and modifications to the present embodiment, which may not creatively contribute to the present application as required by those skilled in the art after reading the present specification, are all protected by patent laws within the scope of claims of the present application.
Claims (7)
1. A preparation method of vermicular cast iron with a graphite structure with high spheroidization rate in an inner cavity is characterized by comprising the following steps: comprising the following steps:
Smelting: weighing raw materials according to the following proportion ：C：3.50-3.65wt%,Si：2.50-2.80wt%,Mn：0.25-0.30wt%,Mo：0.15-0.25wt%,V：0.08-0.12wt%,Mg：0.015-0.019wt%,S≤0.03wt%,P≤0.04wt%,, wherein the balance of Fe and unavoidable impurities, and smelting the raw materials into molten iron;
Inoculating: pouring the molten iron into a ladle, and adding a vermiculizer and an inoculant into the ladle during pouring; the vermiculizer comprises the following components: si:42-48wt%, ca:2.0-2.5wt%, al 0.5-1wt%, re:5.5-6.5wt%, mg:5.0 to 6.0wt% of Fe and unavoidable impurities in balance; the adding amount of the vermiculizer is 0.6-0.8wt% of the molten iron; the inoculant comprises the following components: si:70-75wt%, ce:1.5-2wt%, ca:0.75-1.25wt% of Al, 0.75-1.25wt% of Fe and unavoidable impurities in balance; the addition amount of the inoculant is 0.3-0.7wt% of the molten iron;
pouring: pouring the inoculated molten iron, and annealing and cooling after pouring is finished;
When in inoculation, the vermiculizer is put into a hanging bag, and the vermiculizer is covered by the inoculant; and during inoculation, the mass ratio of the vermiculizer to the inoculant is 1:1.
2. The method for preparing vermicular cast iron with high spheroidization graphite structure of inner cavity according to claim 1, wherein the method comprises the following steps: when smelting, the smelting temperature is 1560-1600 ℃.
3. The method for preparing vermicular cast iron with high spheroidization graphite structure of inner cavity according to claim 1, wherein the method comprises the following steps: when the inoculation is carried out, the inoculation temperature is 1530-1550 ℃ and the inoculation time is 2min.
4. The method for preparing vermicular cast iron with high spheroidization graphite structure of inner cavity according to claim 1, wherein the method comprises the following steps: during pouring, inoculant is also added for stream inoculation, and the addition amount of the inoculant is 0.035-0.05wt% of the pouring liquid.
5. The method for preparing vermicular cast iron with high spheroidization graphite structure of inner cavity according to claim 1, wherein the method comprises the following steps: in the casting process, the casting temperature is 1390-1430 ℃ and the casting time is 5-7min.
6. The method for preparing vermicular cast iron with high spheroidization graphite structure of inner cavity of claim 5, wherein the method comprises the following steps: the concrete process during pouring is as follows: pouring the inoculated molten iron into a mould, forming a glass mould after pouring molding, taking out the molded glass mould from the mould, carrying out annealing treatment, heating the glass mould to 955-958 ℃, preserving heat for 10 hours, cooling to 425 ℃ along with a furnace, and discharging from the furnace for air cooling to normal temperature.
7. Vermicular cast iron, its characterized in that: a method of preparing vermicular cast iron employing the high spheroidization graphite structure of any one of claims 1-6.
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| CN107447158A (en) * | 2017-07-17 | 2017-12-08 | 常熟市精工模具制造有限公司 | The preparation method of high alloy black vermicular cast iron glass mold material |
| CN109266803A (en) * | 2018-11-02 | 2019-01-25 | 常熟市金诺精工模具有限公司 | The manufacturing method of vermicular cast iron glass ware mould material |
| CN109371315A (en) * | 2018-10-24 | 2019-02-22 | 东风商用车有限公司 | High-strength vermicular graphite cast iron and preparation method thereof |
| CN111004968A (en) * | 2020-02-15 | 2020-04-14 | 溧阳市联华机械制造有限公司 | High-silicon heat-resistant vermicular graphite cast iron with thermal fatigue resistance and high performance and preparation method thereof |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107447158A (en) * | 2017-07-17 | 2017-12-08 | 常熟市精工模具制造有限公司 | The preparation method of high alloy black vermicular cast iron glass mold material |
| CN109371315A (en) * | 2018-10-24 | 2019-02-22 | 东风商用车有限公司 | High-strength vermicular graphite cast iron and preparation method thereof |
| CN109266803A (en) * | 2018-11-02 | 2019-01-25 | 常熟市金诺精工模具有限公司 | The manufacturing method of vermicular cast iron glass ware mould material |
| CN111004968A (en) * | 2020-02-15 | 2020-04-14 | 溧阳市联华机械制造有限公司 | High-silicon heat-resistant vermicular graphite cast iron with thermal fatigue resistance and high performance and preparation method thereof |
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