CN111254249A - Method for producing high-strength thick gray cast iron - Google Patents
Method for producing high-strength thick gray cast iron Download PDFInfo
- Publication number
- CN111254249A CN111254249A CN202010208452.4A CN202010208452A CN111254249A CN 111254249 A CN111254249 A CN 111254249A CN 202010208452 A CN202010208452 A CN 202010208452A CN 111254249 A CN111254249 A CN 111254249A
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- Prior art keywords
- casting
- gray cast
- cast iron
- scrap steel
- strength thick
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Classifications
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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
- C21C1/08—Manufacture of cast-iron
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/06—Cast-iron alloys containing chromium
-
- 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
- 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 production method of high-strength thick gray cast iron, which comprises the following steps: 1) feeding inspection, namely performing classification detection on various raw materials; 2) blanking, blanking pig iron and scrap steel into an electric furnace for smelting, sequentially adding return materials, a proper amount of ferromanganese, ferrosilicon, iron sulfide, tin ore and chromium ore into the electric furnace, adding a recarburizing agent once, adding scrap steel in different times, adding the scrap steel again until 80% of molten iron in the furnace is filled when the molten iron is in a molten state, adding the recarburizing agent twice, and adding the scrap steel again; the diameter of the carburant is 3-8 mm; 3) discharging soup and carrying out primary inoculation; 4) turning ladle and carrying out secondary inoculation; 5) casting the secondarily inoculated molten iron into a sand mold; adopting a low-temperature fast casting mode, wherein the temperature is 1360-1380 ℃, and the casting speed is 15 kg/s; effectively ensuring the compact structure of the casting and preserving the heat in the casting sand mold for 120-140 min. The invention realizes the production of high-strength castings and avoids the problem of splitting of the castings due to load failure caused by long-time centrifugal rotation operation.
Description
Technical Field
The invention belongs to the technical field of casting processes, and particularly relates to a production method of high-strength thick and large gray cast iron.
Background
The large gray iron part has longer solidification time in the cooling stage and long graphite growth period because of larger casting size and wall thickness, and the casting strength and fatigue strength are reduced because of larger graphite length. The conventional carburant is added at the initial stage of smelting, although the carburant can be better absorbed when molten iron is boiled, the burning loss of element C in the dissolving process is serious, and the activation degree of the molten iron is reduced due to repeated high temperature in the later stage smelting process of the molten iron. The cast flywheel product is easy to generate load failure and material fracture under the long-time action of high-speed rotating centrifugal force.
Disclosure of Invention
The invention aims to solve the technical problems and provides a production method of high-strength thick and large gray cast iron, so that high-strength castings can be produced, and the problem that the castings are split due to load failure caused by long-time centrifugal rotation operation is solved. In order to achieve the purpose, the technical scheme of the invention is as follows:
the production method of the high-strength thick gray cast iron comprises the following steps:
1) feeding inspection, namely performing classification detection on various raw materials;
2) blanking, blanking pig iron and scrap steel into an electric furnace for smelting, sequentially adding return materials, a proper amount of ferromanganese, ferrosilicon, iron sulfide, tin ore and chromium ore into the electric furnace, adding a recarburizing agent once, adding scrap steel in different times, adding the scrap steel again until 80% of molten iron in the furnace is filled when the molten iron is in a molten state, adding the recarburizing agent twice, and adding the scrap steel again; the diameter of the carburant is 3-8 mm;
3) discharging soup and carrying out primary inoculation;
4) turning ladle and carrying out secondary inoculation;
5) casting the secondarily inoculated molten iron into a sand mold; adopting a low-temperature fast casting mode, wherein the temperature is 1360-1380 ℃, and the casting speed is 15 kg/s; effectively ensuring the compact structure of the casting and preserving the heat in the casting sand mold for 120-140 min.
Specifically, the method also comprises quality detection components after the step 2), and the components of the stock in the electric furnace are detected.
Specifically, in the step 3), a magnesium inoculant is adopted, the inoculation time is 11-12s, and the temperature is controlled to 1360-1380 ℃.
Specifically, in the step 4), a barium inoculant is adopted, the inoculation time is 11-12s, and the temperature is controlled to 1360-1380 ℃.
Specifically, the step 4) and the step 5) further comprise the steps of mixing powder and molding sand, carrying out metering and sand treatment, and carrying out molding and molding by using a mold after the sand treatment.
Specifically, the step 5) is followed by a step 6) of demoulding, and the recovered sand is re-contained into the mixed powder and the moulding sand.
Specifically, the step 6) is followed by a step 7) of separating a casting head, and re-fusing the return materials separated by the casting head into the blanking electric furnace.
Specifically, the step 7) is followed by a step 8) of sand washing, grinding, casting size measurement, appearance inspection, warehousing and shipment.
Compared with the prior art, the production method of the high-strength thick and large gray cast iron has the beneficial effects that:
the diameter of the carburant is 3 mm; the melting time of the recarburizer can be effectively adjusted by controlling the particle diameter of the recarburizer, and the activation of molten iron in enough time is ensured, so that the molten iron has lower supercooling degree; in the process of solidification of molten iron, graphite precipitation can be delayed, the size of graphite can be ensured to be small, the supercooling degree generated by excessive use of alloy can be offset, and in the process of smelting, the molten iron has lower supercooling degree under a lower CE value, so that a high-strength casting is obtained, and the problem that the casting is split due to load failure caused by long-time centrifugal rotation operation is avoided.
Detailed Description
The technical solutions in the embodiments of the present invention are described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments.
Example 1:
the embodiment is a production method of high-strength thick and large gray cast iron, which comprises the following steps:
1) performing feeding inspection, namely performing classification detection on various raw materials, including pig iron, scrap steel, ferromanganese, ferrosilicon, molding sand, blending powder, a recarburizing agent and an inoculating agent;
2) blanking, blanking pig iron and scrap steel into an electric furnace for smelting, adding 2.5T of return materials, a proper amount of ferromanganese, ferrosilicon, iron sulfide, tin ore and chromium ore into a 6T electric furnace, adding 35kg of carburant once, 500kg of scrap steel twice, 500kg of scrap steel three times and 800kg of scrap steel four times; realizing efficient molten iron smelting, when the molten iron is in a molten state, adding the scrap steel again until the molten iron reaches 4.8T, adding 40kg of carburant for the second time, and adding 1200kg of scrap steel;
the diameter of the carburant is 3 mm; the grain diameter control of the recarburizer can effectively adjust the melting time of the recarburizer, and ensure the activation of molten iron in enough time, so that the molten iron has lower supercooling degree.
The recarburizing agent is added into the furnace when the scrap steel is added into the furnace to reach 4.8T molten iron, and the supercooling degree of the molten iron is longer than that of the added inoculant because the added inoculant has effectiveness; in the process of solidification of molten iron, graphite precipitation can be delayed, the size of graphite can be ensured to be small, the supercooling degree generated by excessive use of alloy can be offset, and in the process of smelting, the molten iron has lower supercooling degree under a lower CE value, so that a high-strength casting is obtained, and the problem that the casting is split due to load failure caused by long-time centrifugal rotation operation is avoided.
3) Measuring the quality components, and detecting the components of the stock in the electric furnace;
4) discharging soup and carrying out primary inoculation; adopting magnesium inoculant, wherein the inoculation time is 12s, and the temperature is controlled at 1380 ℃;
5) turning ladle and carrying out secondary inoculation; adopting barium inoculant, wherein the inoculation time is 11s, and the temperature is controlled to 1360 ℃;
6) mixing powder and molding sand, and carrying out metering and sand treatment;
7) after sand treatment, a mould is used for moulding;
8) casting the secondarily inoculated molten iron into a sand mold; adopting a low-temperature fast casting mode, wherein the temperature is 1380 ℃, and the casting speed is 15 kg/s; the compact structure of the casting is effectively ensured, and the heat preservation is carried out in the sand mold of the casting for 120min, so that the mechanical property of the thicker position of the casting is uniform;
9) demoulding, namely re-containing the recovered sand into mixed powder and moulding sand;
10) separating a casting head, and re-fusing the return materials separated by the casting head into a blanking electric furnace;
11) washing sand;
12) grinding, wherein the casting is ground;
13) and measuring the size of the casting, checking the appearance, and performing warehousing and shipment processes.
The casting comprises 3.15-3.2% of C, Si: 1.75-1.8%, Mn: 0.9-0.95%, P: < 0.1%, S0.08-0.12%, Cu: 0.85-0.9%, Cr: 0.15-0.2%, Sn 0.06-0.07%, Sb: 0.03-0.04%, barium inoculant: 0.3%, magnesium-based inoculant: 0.4%, and the balance of Fe and impurities.
Example 2:
the difference on the basis of example 1 is that:
2) the diameter of the carburant is 8 mm;
4) discharging soup and carrying out primary inoculation; adopting magnesium inoculant, wherein the inoculation time is 11s, and the temperature is controlled to 1360 ℃;
5) turning ladle and carrying out secondary inoculation; adopting barium inoculant, wherein the inoculation time is 12s, and the temperature is controlled at 1380 ℃;
8) casting the secondarily inoculated molten iron into a sand mold; adopting a low-temperature fast casting mode, wherein the temperature is 1360 ℃, and the casting speed is 15 kg/s; and preserving heat for 140min in a casting sand mold.
Example 3:
the difference on the basis of example 1 is that:
2) the diameter of the carburant is 5 mm;
4) discharging soup and carrying out primary inoculation; adopting magnesium inoculant, wherein the inoculation time is 11s, and the temperature is controlled at 1370 ℃;
5) turning ladle and carrying out secondary inoculation; adopting barium inoculant, wherein the inoculation time is 12s, and the temperature is controlled at 1370 ℃;
8) casting the secondarily inoculated molten iron into a sand mold; adopting a low-temperature fast casting mode, wherein the temperature is 1370 ℃, and the casting speed is 15 kg/s; and keeping the temperature in a casting sand mold for 130 min.
Comparative example:
the difference on the basis of example 1 is that:
adding sufficient carburant and return materials into the electric furnace for smelting.
When the embodiment 1 is applied, strength and hardness samples are taken at four positions of the thickness (50mm) of a casting body through refining, magnesium inoculant addition and a reasonable pouring system, the tensile strength of the casting material performance is greater than 250MPa, and the hardness is 229 HB and 312 HB; taking a gold phase test sample at a position with the thickness (14mm), wherein the graphite shape is ASTM I (sheet), and the graphite arrangement A + B is 93-96%; graphite size: 4-7 graphite lengths; the non-graphite arrangement C form, minimum 95% pearlite, maximum 5% ferrite, no carbides (cementite and ledeburite) meeting the standard specification. When the comparative example is applied, one strength and hardness test sample is taken at the position of the thickness (50mm) of the casting body, and one gold phase test sample is taken at the position of the thickness (14 mm).
Test data:
according to the data analysis, the diameter size of the carburant and the time of adding the carburant into the electric furnace determine the performance of the casting, particularly the hardness and the tensile strength of the casting, and the embodiment 1 has the excellent performance effect of the thick and large casting.
What has been described above are merely some embodiments of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the inventive concept thereof, and these changes and modifications can be made without departing from the spirit and scope of the invention.
Claims (8)
1. The production method of the high-strength thick gray cast iron is characterized by comprising the following steps:
1) feeding inspection, namely performing classification detection on various raw materials;
2) blanking, blanking pig iron and scrap steel into an electric furnace for smelting, sequentially adding return materials, a proper amount of ferromanganese, ferrosilicon, iron sulfide, tin ore and chromium ore into the electric furnace, adding a recarburizing agent once, adding scrap steel in different times, adding the scrap steel again until 80% of molten iron in the furnace is filled when the molten iron is in a molten state, adding the recarburizing agent twice, and adding the scrap steel again; the diameter of the carburant is 3-8 mm;
3) discharging soup and carrying out primary inoculation;
4) turning ladle and carrying out secondary inoculation;
5) casting the secondarily inoculated molten iron into a sand mold; adopting a low-temperature fast casting mode, wherein the temperature is 1360-1380 ℃, and the casting speed is 15 kg/s; effectively ensuring the compact structure of the casting and preserving the heat in the casting sand mold for 120-140 min.
2. A method for producing high-strength thick gray cast iron according to claim 1, characterized in that: and 2) detecting the components of the stock in the electric furnace after the step 2).
3. A method for producing high-strength thick gray cast iron according to claim 1, characterized in that: in the step 3), a magnesium inoculant is adopted, the inoculation time is 11-12s, and the temperature is controlled to 1360-1380 ℃.
4. A method for producing high-strength thick gray cast iron according to claim 1, characterized in that: in the step 4), a barium inoculant is adopted, the inoculation time is 11-12s, and the temperature is controlled at 1360-1380 ℃.
5. A method for producing high-strength thick gray cast iron according to claim 1, characterized in that: and step 4) and step 5) further comprise the steps of mixing powder and molding sand, metering and sand processing, and molding by using a mold after sand processing.
6. A method for producing high-strength thick gray cast iron according to claim 5, wherein: and step 5) after the step 6), demoulding, and re-containing the recovered sand into mixed powder and moulding sand.
7. A method for producing high-strength thick gray cast iron according to claim 6, wherein: and step 6) further comprises step 7) of separating a casting head, and re-fusing the return material separated by the casting head into the blanking electric furnace.
8. A method for producing high-strength thick gray cast iron according to claim 7, wherein: and 7) after the step 8), the steps of sand washing, grinding, casting size measurement, appearance inspection and warehousing and shipment are also included.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202010208452.4A CN111254249A (en) | 2020-03-23 | 2020-03-23 | Method for producing high-strength thick gray cast iron |
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| CN202010208452.4A CN111254249A (en) | 2020-03-23 | 2020-03-23 | Method for producing high-strength thick gray cast iron |
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| CN111254249A true CN111254249A (en) | 2020-06-09 |
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| CN202010208452.4A Pending CN111254249A (en) | 2020-03-23 | 2020-03-23 | Method for producing high-strength thick gray cast iron |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113862417A (en) * | 2021-10-09 | 2021-12-31 | 中钢集团邢台机械轧辊有限公司 | Process method for producing molten iron by intermediate frequency furnace |
| CN114703419A (en) * | 2022-03-31 | 2022-07-05 | 瑞安博宇科技股份有限公司 | Production method of galvanized cast iron for commutator production |
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| CN114703419A (en) * | 2022-03-31 | 2022-07-05 | 瑞安博宇科技股份有限公司 | Production method of galvanized cast iron for commutator production |
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Application publication date: 20200609 |