CN117604371A - Spheroidal graphite cast iron and preparation method thereof - Google Patents
Spheroidal graphite cast iron and preparation method thereof Download PDFInfo
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- CN117604371A CN117604371A CN202311702120.1A CN202311702120A CN117604371A CN 117604371 A CN117604371 A CN 117604371A CN 202311702120 A CN202311702120 A CN 202311702120A CN 117604371 A CN117604371 A CN 117604371A
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- graphite cast
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- 229910001141 Ductile iron Inorganic materials 0.000 title claims abstract description 99
- 238000002360 preparation method Methods 0.000 title abstract description 18
- 238000000137 annealing Methods 0.000 claims abstract description 37
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 16
- 238000003723 Smelting Methods 0.000 claims abstract description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 113
- 229910052742 iron Inorganic materials 0.000 claims description 52
- 239000002054 inoculum Substances 0.000 claims description 42
- 238000001816 cooling Methods 0.000 claims description 34
- 238000005266 casting Methods 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 15
- 239000012535 impurity Substances 0.000 claims description 13
- 239000007788 liquid Substances 0.000 claims description 12
- 239000000126 substance Substances 0.000 claims description 12
- 229910052698 phosphorus Inorganic materials 0.000 claims description 9
- 229910052717 sulfur Inorganic materials 0.000 claims description 9
- 239000003795 chemical substances by application Substances 0.000 claims description 7
- 239000002994 raw material Substances 0.000 claims description 7
- UVGLBOPDEUYYCS-UHFFFAOYSA-N silicon zirconium Chemical group [Si].[Zr] UVGLBOPDEUYYCS-UHFFFAOYSA-N 0.000 claims description 6
- 229910000519 Ferrosilicon Inorganic materials 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 238000002844 melting Methods 0.000 claims 1
- 230000008018 melting Effects 0.000 claims 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 29
- 229910002804 graphite Inorganic materials 0.000 abstract description 22
- 239000010439 graphite Substances 0.000 abstract description 22
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 9
- 239000010949 copper Substances 0.000 abstract description 9
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 abstract description 8
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 abstract description 8
- 229910052799 carbon Inorganic materials 0.000 abstract description 8
- 229910052802 copper Inorganic materials 0.000 abstract description 8
- 230000000694 effects Effects 0.000 abstract description 8
- 229910052749 magnesium Inorganic materials 0.000 abstract description 8
- 239000011777 magnesium Substances 0.000 abstract description 8
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 abstract description 7
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052710 silicon Inorganic materials 0.000 abstract description 7
- 239000010703 silicon Substances 0.000 abstract description 7
- 229910052726 zirconium Inorganic materials 0.000 abstract description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 6
- 229910052782 aluminium Inorganic materials 0.000 abstract description 6
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 abstract description 6
- 239000010955 niobium Substances 0.000 abstract description 6
- 229910052758 niobium Inorganic materials 0.000 abstract description 6
- 238000011081 inoculation Methods 0.000 abstract description 5
- 238000013461 design Methods 0.000 abstract description 3
- 239000011573 trace mineral Substances 0.000 abstract description 3
- 235000013619 trace mineral Nutrition 0.000 abstract description 3
- 150000001875 compounds Chemical class 0.000 abstract description 2
- 238000005058 metal casting Methods 0.000 abstract description 2
- 238000005728 strengthening Methods 0.000 abstract description 2
- GPPXJZIENCGNKB-UHFFFAOYSA-N vanadium Chemical compound [V]#[V] GPPXJZIENCGNKB-UHFFFAOYSA-N 0.000 abstract 2
- 230000000052 comparative effect Effects 0.000 description 15
- 239000000203 mixture Substances 0.000 description 8
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 6
- 229910001562 pearlite Inorganic materials 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 4
- 229910001566 austenite Inorganic materials 0.000 description 4
- 238000011010 flushing procedure Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 229910001338 liquidmetal Inorganic materials 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- 229910000616 Ferromanganese Inorganic materials 0.000 description 1
- 229910000628 Ferrovanadium Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910000805 Pig iron Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 229910026551 ZrC Inorganic materials 0.000 description 1
- OTCHGXYCWNXDOA-UHFFFAOYSA-N [C].[Zr] Chemical compound [C].[Zr] OTCHGXYCWNXDOA-UHFFFAOYSA-N 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000005087 graphitization Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 description 1
- PNXOJQQRXBVKEX-UHFFFAOYSA-N iron vanadium Chemical compound [V].[Fe] PNXOJQQRXBVKEX-UHFFFAOYSA-N 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
Classifications
-
- 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
- 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
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The invention relates to the technical field of metal casting, and particularly discloses spheroidal graphite cast iron and a preparation method thereof. The spheroidal graphite cast iron provided by the invention comprises carbon, silicon, manganese, copper, vanadium, niobium, aluminum, zirconium and magnesium elements. The invention adopts the design thought of low carbon and low silicon, and by adding elements of manganese, copper, vanadium, niobium, aluminum, zirconium and magnesium and adjusting the dosage of trace elements, the invention achieves the effect of compound strengthening, further improves the strength, toughness and spheroidization effect of the spheroidal graphite cast iron, and greatly improves the problem of poor comprehensive performance of the existing spheroidal graphite cast iron. The invention also provides a preparation method of the spheroidal graphite cast iron, and the prepared spheroidal graphite cast iron has excellent spheroidization rate and spheroidization grade by controlling the smelting temperature, the spheroidization temperature and the inoculation temperature and carrying out twice annealing treatment on the spheroidal graphite cast iron, and the prepared spheroidal graphite cast iron has more graphite nodules, so that the strength and toughness of the spheroidal graphite cast iron are further improved.
Description
Technical Field
The invention relates to the technical field of metal casting, and particularly discloses spheroidal graphite cast iron and a preparation method thereof.
Background
Because of its advantages in manufacture and economy, it has high strength, good toughness and good wear resistance, and it is used as an excellent engineering material to replace carbon steel, alloy steel, etc. and may be used widely in crankshaft, gear, connecting rod, casing, cast pipe, etc. of internal combustion engine. However, with the continuous improvement of the power of the engine, the performance requirements on related equipment and parts are improved to a certain extent, and some parts working under special environmental conditions such as high speed, high pressure, high temperature and the like often cause accelerated damage due to the special environment, and even cause equipment to be scrapped seriously, so that huge losses are caused. Currently, QT500-7 is mainly adopted by a traditional transmission shaft, a differential mechanism shell, a bracket and the like for an automobile chassis and a tractor chassis, but the traditional transmission shaft, the differential mechanism shell, the bracket and the like are easy to crack, so that the strength and the toughness are reduced in the subsequent use process, and the service life is greatly shortened. Therefore, the preparation method of the ductile cast iron with high strength, high toughness and high spheroidization rate has important significance.
Disclosure of Invention
Aiming at the problems, the invention provides the spheroidal graphite cast iron and the preparation method thereof, and the spheroidal graphite cast iron provided by the invention adopts the design thought of low carbon and low silicon, and the compound strengthening effect is achieved by adding elements of manganese, copper, vanadium, niobium, aluminum, zirconium and magnesium and adjusting the dosage of trace elements, so that the strength, toughness and spheroidization effect of the spheroidal graphite cast iron are further improved, and the problem of poor comprehensive performance of the existing spheroidal graphite cast iron is greatly improved.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
the first aspect of the invention provides spheroidal graphite cast iron which comprises the following chemical components in percentage by mass: c:2.7% -3.1%, si:1.8% -2.2%, mn:0.36% -0.4%, cu:0.32% -0.38%, V:0.13% -0.16%, nb:0.16% -0.22%, al:3.1% -3.5%, zr:0.15% -0.18%, mg:0.04% -0.06%, P is less than or equal to 0.03%, S is less than or equal to 0.02%, and the balance is Fe and unavoidable impurities.
Compared with the prior art, the components of the spheroidal graphite cast iron provided by the invention reduce the content of carbon and silicon elements to a certain extent, and solve the problems that the graphite floats and the mechanical property of the spheroidal graphite cast iron is reduced due to the excessive carbon content and the toughness and the strength are easily reduced due to the excessive silicon content; however, the reduction of the carbon content and the silicon content may cause defects such as shrinkage cavity, loosening and the like of the spheroidal graphite cast iron, thereby influencing the graphite separationMechanical properties of cloth and spheroidization and ductile iron; in this regard, through extensive research, the inventors have improved the toughness and strength of spheroidal graphite cast iron by adding alloying elements such as manganese, copper, vanadium, niobium, aluminum, zirconium and magnesium, and have further improved the spheroidization rate and spheroidization grade of castings; specifically, a proper amount of manganese element can improve the stability of pearlite in the spheroidal graphite cast iron and promote (Fe, mn) 3 C is formed, so that the spheroidal graphite cast iron is facilitated to have excellent toughness and high strength; the introduction of copper element can reduce the diffusion speed of carbon atoms in the austenitic eutectoid transformation process, promote the generation of pearlite and refine the pearlite, precipitate from solid solution, strengthen a metal matrix, thereby improving the tensile strength, round spheroidal graphite by refining graphite nodules, improve the spheroidization rate and spheroidization grade, and further improve the toughness of spheroidal graphite cast iron by reducing the segregation degree of carbide on grain boundaries; according to the invention, by controlling the addition amount of copper and manganese, two elements play a role in the spheroidal graphite cast iron together, so that the toughness and strength of the spheroidal graphite cast iron are greatly improved; a part of vanadium element with specific content exists in the ball-milling cast iron in the form of vanadium carbonitride, and the vanadium element is distributed at the grain boundary, so that the strength and the hardness of the ductile iron are improved to a certain extent; the addition of the niobium element can refine ferrite grains, improve the toughness of a metal matrix, promote the formation of graphite nodules, increase the roundness of the graphite nodules, further improve the spheroidization rate, improve the formation of pearlite by reducing the temperature of austenite like pearlite transformation in the spheroidal graphite cast iron, improve the strength and the hardness of the spheroidal graphite cast iron, reduce the diffusion speed of carbon in the austenite and improve the toughness of the spheroidal graphite cast iron; the aluminum element can form a stronger chemical bond with the iron element so as to improve the strength and the hardness of the spheroidal graphite cast iron, the aluminum element can refine ferrite grains, reduce carbide content and improve the toughness of the spheroidal graphite cast iron, and the aluminum element can further promote the formation of graphite nodules, increase the roundness of the graphite nodules and further improve the spheroidization rate; the zirconium element can form more surface tension of liquid metal with the iron element, is favorable for the anisotropic growth of graphite, improves the spheroidization rate, and can also form compact cast state by improving the viscosity of the liquid metal and is favorable for spheroidal graphite cast ironThe structure is adopted, so that the strength and the toughness of the spheroidal graphite cast iron are improved; the addition of the magnesium element is beneficial to the transformation from austenite to ferrite, reduces the residual austenite, further improves the toughness of the spheroidal graphite cast iron, and can also improve the toughness of the spheroidal graphite cast iron by separating out carbide on a grain boundary, and the research shows that the spheroidization effect can be improved to a certain extent by adding a certain content of the magnesium element; according to the invention, the aluminum, zirconium and magnesium elements are further selected, the addition amounts of the three elements are limited, and the hardness, strength, toughness and spheroidization rate of the spheroidal graphite cast iron are improved through the mutual coordination and synergistic effect of the three elements, so that the prepared spheroidal graphite cast iron has excellent mechanical properties.
The nodular cast iron provided by the invention adopts a low-carbon and low-silicon design thought, and by adding elements of manganese, copper, vanadium, niobium, aluminum, zirconium and magnesium and adjusting the dosage of trace elements, the effect of composite reinforcement is achieved, the strength, toughness and spheroidization effect of the nodular cast iron are further improved, and the problem of poor comprehensive performance of the existing nodular cast iron is greatly improved.
The second aspect of the present invention provides a method for preparing the spheroidal graphite cast iron, comprising the steps of:
s1, smelting raw materials at 1520-1630 ℃ to obtain molten iron;
s2, spheroidizing the molten iron at 1510-1540 ℃ to obtain spheroidized molten iron;
s3, adding a first inoculant into the spheroidized iron liquid at 1480-1500 ℃, then adding a second inoculant along with the flow, and inoculating for 40-50S at 1520-1580 ℃ to obtain inoculated iron liquid;
s4, pouring the inoculated molten iron into a die at the temperature of 1420-1480 ℃ and cooling to room temperature at the cooling rate of 30-35 ℃ per hour to obtain a nodular cast iron casting;
s5, under the inert atmosphere, carrying out primary annealing on the ductile cast iron casting at 900-950 ℃, and then carrying out secondary annealing at 800-830 ℃ to obtain the ductile cast iron.
According to the preparation method of the spheroidal graphite cast iron, spheroidization is carried out at a specific temperature, so that graphite precipitated in the solidification process of molten iron is changed from a flake shape into a sphere shape, the roundness and the quantity of graphite are improved, and the strength and the plasticity of the spheroidal graphite cast iron are improved; furthermore, the invention also limits twice inoculation, carries out the first inoculation at a specific temperature, can promote graphitization, improves the roundness, the number of balls, the ball diameter and the distance between graphite balls, increases the number of eutectic cells by improving the shape and the distribution of graphite, improves the strength of spheroidal graphite cast iron, and is beneficial to more uniform, tiny and compact graphite balls by carrying out the second inoculation at the specific temperature, thereby improving the strength and the toughness of castings and improving the spheroidization rate and the spheroidization grade of castings; according to the invention, the twice inoculation is respectively carried out at a specific temperature, so that the morphology and the distribution of graphite are effectively optimized, and the strength and the toughness of castings are improved; in S4, the specific cooling rate is favorable for obtaining finer grain structures and improving the strength of the casting; the invention further carries out twice annealing treatment on the spheroidal graphite cast, wherein the temperature of the first annealing is higher, so that casting stress can be eliminated, graphite spheroidization can be promoted, the temperature of the second annealing is lower than that of the first annealing, the structure can be adjusted, grains can be refined, and the spheroidization rate of spheroidal graphite cast can be further improved by limiting the temperature of the second annealing, so that the strength and toughness of the spheroidal graphite cast are greatly improved.
In S1, the raw materials include pig iron, scrap steel, recycled materials, ferromanganese, ferrovanadium, silicon aluminum alloy, niobium simple substance, zirconium carbide and pure copper with low sulfur, phosphorus and manganese content, and the configuration proportion can be according to the element components in the raw materials to meet the component proportion in the spheroidal graphite cast iron.
Preferably, in S1, the smelting time is 60min-70min.
Preferably, in S2, the spheroidizing time is 40S-50S.
Preferably, in S2, the spheroidizing agent is added by a flushing method during the spheroidizing treatment.
Preferably, in the step S2, the adding amount of the nodulizer is 0.5-0.8% of the mass of the molten iron during the nodulizing treatment.
Further preferably, the nodulizer comprises the following components in percentage by weight: mg:5% -7%, si:30% -35%, RE:1% -2%, ca:1% -1.2% of iron and the balance of unavoidable impurities.
The optimized spheroidizing agent is beneficial to improving the spheroidizing effect, so that the strength and toughness of the spheroidal graphite cast iron are improved.
Preferably, in S3, the addition amount of the first inoculant is 0.2-0.3% of the mass of the molten iron.
Preferably, in S3, the addition amount of the second inoculant is 0.1-0.15% of the mass of the molten iron.
Further preferably, the first inoculant is a 75 ferrosilicon inoculant.
Further preferably, the second inoculant is a silicon zirconium inoculant.
The preferred inoculant is advantageous for further improving the strength and toughness of the spheroidal graphite cast iron.
Further preferably, the manufacturer of the silicon zirconium inoculant is an angyang county changxin special alloy limited company.
Preferably, the room temperature in S4 is in the range of 10℃to 30 ℃.
Preferably, in S5, the time of the first annealing is 50min-70min.
Preferably, in S5, the time of the second annealing is 90min-110min.
The preferable annealing time can ensure uniform temperature distribution, realize the structure adjustment of materials and further improve the strength and toughness of the spheroidal graphite cast iron.
Preferably, in S5, the cooling rate in the first annealing and the second annealing is 18 ℃/h-20 ℃/h.
The preferable cooling rate can avoid the generation of internal stress caused by rapid cooling, and further improve the toughness and strength of the spheroidal graphite cast iron.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Example 1
The embodiment provides spheroidal graphite cast iron which comprises the following chemical components in percentage by mass: c:3.1%, si:1.8%, mn:0.4%, cu:0.32%, V:0.16%, nb:0.16%, al:3.1%, zr:0.18%, mg:0.04%, P:0.012%, S:0.01%, the balance being Fe and unavoidable impurities.
The spheroidal graphite cast iron is prepared by the following preparation method:
s1, smelting raw materials at 1630 ℃ for 60min to obtain molten iron;
s2, adding a spheroidizing agent into the molten iron at 1510 ℃ by adopting a flushing method, and spheroidizing for 40S to obtain spheroidized molten iron; wherein, the adding amount of the nodulizer is 0.5 percent of the mass of the molten iron, and the nodulizer comprises the following components in percentage by weight: mg:7%, si:35%, RE:1%, ca:1.2% of iron and unavoidable impurities in balance;
s3, adding a first inoculant into the spheroidized iron liquid at 1480 ℃, then adding a second inoculant along with the flow, and inoculating for 50S at 1520 ℃ to obtain inoculated iron liquid; wherein the addition amount of the first inoculant is 0.2% of the mass of the molten iron, and the first inoculant is 75 ferrosilicon inoculant; the addition amount of the second inoculant is 0.15% of the mass of the molten iron, and the second inoculant is a silicon-zirconium inoculant produced by Anyang county Changxin special alloy Co., ltd;
s4, pouring the inoculated molten iron into a mould at the temperature of 1420 ℃, and cooling to room temperature at the cooling rate of 30-35 ℃ per hour to obtain a nodular cast iron casting;
s5, carrying out primary annealing on the spheroidal graphite cast iron at 950 ℃ in an inert atmosphere, controlling the annealing time to be 50min, cooling to room temperature at a cooling rate of 18 ℃/h, then carrying out secondary annealing at 830 ℃, controlling the annealing time to be 110min, and cooling at a cooling rate of 20 ℃/h to obtain the spheroidal graphite cast iron.
Example 2
The embodiment provides spheroidal graphite cast iron which comprises the following chemical components in percentage by mass: c:2.7%, si:2.2%, mn:0.36%, cu:0.38%, V:0.13%, nb:0.22%, al:3.5%, zr:0.15%, mg:0.06%, P:0.01%, S:0.013%, and the balance of Fe and unavoidable impurities.
The spheroidal graphite cast iron is prepared by the following preparation method:
s1, smelting raw materials at 1520 ℃ for 70min to obtain molten iron;
s2, adding a spheroidizing agent into the molten iron at 1540 ℃ for spheroidizing treatment for 50S by adopting a flushing method, so as to obtain spheroidized molten iron; wherein, the adding amount of the nodulizer is 0.8 percent of the mass of the molten iron, and the nodulizer comprises the following components in percentage by weight: mg:5%, si:30%, RE:2%, ca:1%, the balance being iron and unavoidable impurities;
s3, adding a first inoculant into the spheroidized iron liquid at 1500 ℃, then adding a second inoculant along with the flow, and inoculating for 40S at 1580 ℃ to obtain inoculated iron liquid; wherein the addition amount of the first inoculant is 0.3% of the mass of the molten iron, and the first inoculant is 75 ferrosilicon inoculant; the addition amount of the second inoculant is 0.1% of the mass of the molten iron, and the second inoculant is a silicon-zirconium inoculant produced by Anyang county Changxin special alloy Co., ltd;
s4, pouring the inoculated iron liquid into a mould at 1480 ℃, and cooling to room temperature at a cooling rate of 30-35 ℃ per hour to obtain a nodular cast iron casting;
s5, carrying out primary annealing on the spheroidal graphite cast iron at 900 ℃ in an inert atmosphere, controlling the annealing time to be 70min, cooling to room temperature at a cooling rate of 20 ℃/h, then carrying out secondary annealing at 800 ℃, controlling the annealing time to be 90min, and cooling at a cooling rate of 18 ℃/h to obtain the spheroidal graphite cast iron.
Example 3
The embodiment provides spheroidal graphite cast iron which comprises the following chemical components in percentage by mass: c:3%, si:2%, mn:0.38%, cu:0.36%, V:0.15%, nb:0.2%, al:3.3%, zr:0.16%, mg:0.05%, P:0.02%, S:0.005%, the balance being Fe and unavoidable impurities.
The spheroidal graphite cast iron is prepared by the following preparation method:
s1, smelting raw materials at 1610 ℃ for 65min to obtain molten iron;
s2, adding a spheroidizing agent into the molten iron at 1520 ℃ for spheroidizing for 45S by adopting a flushing method to obtain spheroidized molten iron; wherein, the adding amount of the nodulizer is 0.6 percent of the mass of the molten iron, and the nodulizer comprises the following components in percentage by weight: mg:6%, si:32%, RE:2%, ca:1.1% of iron and unavoidable impurities in balance;
s3, adding a first inoculant into the spheroidized iron liquid at the temperature of 1490 ℃, then adding a second inoculant along with the flow, and inoculating for 45S at the temperature of 1540 ℃ to obtain inoculated iron liquid; wherein the addition amount of the first inoculant is 0.25% of the mass of the molten iron, and the first inoculant is 75 ferrosilicon inoculant; the addition amount of the second inoculant is 0.12% of the mass of the molten iron, and the second inoculant is a silicon-zirconium inoculant produced by Anyang county Changxin special alloy Co., ltd;
s4, pouring the inoculated iron liquid into a die at the temperature of 1460 ℃, and cooling to room temperature at the cooling rate of 30-35 ℃ per hour to obtain a nodular cast iron casting;
s5, under the inert atmosphere, carrying out primary annealing on the spheroidal graphite cast iron casting at the temperature of 920 ℃, controlling the annealing time to be 60min, cooling to room temperature at the cooling rate of 20 ℃/h, then carrying out secondary annealing at the temperature of 810 ℃, controlling the annealing time to be 100min, and cooling at the cooling rate of 20 ℃/h to obtain the spheroidal graphite cast iron.
Comparative example 1
This comparative example provides an as-cast spheroidal graphite cast iron having a chemical composition similar to that of example 1, except that the Cu addition amount is varied, and specifically, the as-cast spheroidal graphite cast iron is composed of the following chemical components in mass percent: c:3.1%, si:1.8%, mn:0.4%, cu:0.45%, V:0.16%, nb:0.16%, al:3.1%, zr:0.18%, mg:0.04%, P:0.012%, S:0.01%, the balance being Fe and unavoidable impurities.
The preparation method of the cast spheroidal graphite cast iron is the same as that of the example 1.
Comparative example 2
This comparative example provides an as-cast spheroidal graphite cast iron having a chemical composition similar to that of example 1, except that no Al is added, and specifically, comprising, in mass percent: c:3.1%, si:1.8%, mn:0.4%, cu:0.32%, V:0.16%, nb:0.16%, zr:0.18%, mg:0.04%, P:0.012%, S:0.01%, the balance being Fe and unavoidable impurities.
The preparation method of the cast spheroidal graphite cast iron is the same as that of the example 1.
Comparative example 3
This comparative example provides an as-cast spheroidal graphite cast iron having a chemical composition similar to that of example 1, except that the Zr addition amount varies, and specifically, consists of the following chemical compositions in mass percent: c:3.1%, si:1.8%, mn:0.4%, cu:0.32%, V:0.16%, nb:0.16%, al:3.1%, zr:0.12%, mg:0.04%, P:0.012%, S:0.01%, the balance being Fe and unavoidable impurities.
The preparation method of the cast spheroidal graphite cast iron is the same as that of the example 1.
Comparative example 4
This comparative example provides an as-cast spheroidal graphite cast iron having the same composition as in example 1, except that: in the preparation method S4, the cooling rate is increased to 50 ℃/h, and other steps are the same as those in the embodiment 1.
Comparative example 5
This comparative example provides an as-cast spheroidal graphite cast iron having the same composition as in example 1, except that: the preparation method specifically comprises the steps of annealing the ductile cast iron casting at 950 ℃ in an inert atmosphere, controlling the annealing time to be 50min, and cooling at a cooling rate of 18 ℃/h to obtain ductile cast iron;
the other steps were the same as in example 1.
Comparative example 6
This comparative example provides an as-cast spheroidal graphite cast iron having the same composition as in example 1, except that: the preparation method specifically comprises the steps of (S5) carrying out primary annealing on the ductile cast iron casting at 830 ℃ in an inert atmosphere, controlling the annealing time to be 50min, cooling to room temperature at a cooling rate of 18 ℃/h, then carrying out secondary annealing at 950 ℃, controlling the annealing time to be 110min, and cooling at a cooling rate of 20 ℃/h to obtain the ductile cast iron;
the other steps were the same as in example 1.
Performance testing
The spheroidal graphite cast iron of examples 1 to 3 and comparative examples 1 to 6 were subjected to mechanical property test and metallographic examination, and specific mechanical property test data are shown in table 1.
Table 1 mechanical properties of as-cast spheroidal graphite cast iron of examples 1 to 3 and comparative examples 1 to 6
As can be seen from the above table, compared with comparative examples 1-6, the spheroidal graphite cast iron provided by examples 1-3 of the invention has excellent mechanical properties, and the prepared spheroidal graphite cast iron has excellent spheroidization rate and spheroidization grade by controlling the composition of elements and combining the preparation method provided by the invention, and the prepared spheroidal graphite cast iron has more graphite nodules, so that the strength and toughness of the spheroidal graphite cast iron are improved.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, or alternatives falling within the spirit and principles of the invention.
Claims (10)
1. An as-cast spheroidal graphite cast iron is characterized by comprising the following chemical components in percentage by mass: c:2.7% -3.1%, si:1.8% -2.2%, mn:0.36% -0.4%, cu:0.32% -0.38%, V:0.13% -0.16%, nb:0.16% -0.22%, al:3.1% -3.5%, zr:0.15% -0.18%, mg:0.04% -0.06%, P is less than or equal to 0.03%, S is less than or equal to 0.02%, and the balance is Fe and unavoidable impurities.
2. A method of producing spheroidal graphite cast iron according to claim 1 comprising the steps of:
s1, smelting raw materials at 1520-1630 ℃ to obtain molten iron;
s2, spheroidizing the molten iron at 1510-1540 ℃ to obtain spheroidized molten iron;
s3, adding a first inoculant into the spheroidized iron liquid at 1480-1500 ℃, then adding a second inoculant along with the flow, and inoculating for 40-50S at 1520-1580 ℃ to obtain inoculated iron liquid;
s4, pouring the inoculated molten iron into a die at the temperature of 1420-1480 ℃ and cooling to room temperature at the cooling rate of 30-35 ℃ per hour to obtain a nodular cast iron casting;
s5, under the inert atmosphere, carrying out primary annealing on the ductile cast iron casting at 900-950 ℃, and then carrying out secondary annealing at 800-830 ℃ to obtain the ductile cast iron.
3. The method for producing spheroidal graphite cast iron according to claim 2 wherein the melting time in S1 is 60 to 70 minutes.
4. The method for producing spheroidal graphite cast iron according to claim 2 wherein the spheroidizing time in S2 is 40S to 50S; and/or
In S2, during spheroidization, the adding amount of the spheroidizing agent is 0.5-0.8% of the mass of the molten iron.
5. The method of producing spheroidal graphite cast iron according to claim 4 wherein the spheroidizing agent comprises the following components in weight percent: mg:5% -7%, si:30% -35%, RE:1% -2%, ca:1% -1.2% of iron and the balance of unavoidable impurities.
6. The method for preparing ductile iron according to claim 2 wherein in S3, the first inoculant is added in an amount of 0.2% to 0.3% by mass of the molten iron; and/or
In S3, the addition amount of the second inoculant is 0.1-0.15% of the mass of the molten iron.
7. The method of claim 2 or 6, wherein the first inoculant is a 75 ferrosilicon inoculant; and/or
The second inoculant is a silicon-zirconium inoculant.
8. The method of claim 7, wherein in S5, the first annealing is performed for 50min to 70min.
9. The method of claim 2, wherein in S5, the second annealing is performed for 90min to 110min.
10. The method for preparing ductile iron according to claim 2 wherein in S5, the cooling rate in the first annealing and the second annealing is 18 ℃/h to 20 ℃/h.
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