CN116411147A - Production method for eliminating fissured nitrogen pores of castings - Google Patents
Production method for eliminating fissured nitrogen pores of castings Download PDFInfo
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- CN116411147A CN116411147A CN202211358224.0A CN202211358224A CN116411147A CN 116411147 A CN116411147 A CN 116411147A CN 202211358224 A CN202211358224 A CN 202211358224A CN 116411147 A CN116411147 A CN 116411147A
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- inoculant
- nitrogen
- nodulizer
- pouring
- fissured
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 63
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 31
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 18
- 238000005266 casting Methods 0.000 title claims abstract description 17
- 239000011148 porous material Substances 0.000 title claims abstract description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 54
- 229910052742 iron Inorganic materials 0.000 claims abstract description 27
- 239000002054 inoculum Substances 0.000 claims abstract description 24
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 19
- 239000010959 steel Substances 0.000 claims abstract description 19
- 239000000463 material Substances 0.000 claims abstract description 18
- 229910000805 Pig iron Inorganic materials 0.000 claims abstract description 14
- 238000003723 Smelting Methods 0.000 claims abstract description 12
- 238000006243 chemical reaction Methods 0.000 claims abstract description 12
- 239000002243 precursor Substances 0.000 claims abstract description 12
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910010271 silicon carbide Inorganic materials 0.000 claims abstract description 12
- 229910000599 Cr alloy Inorganic materials 0.000 claims abstract description 11
- 239000000788 chromium alloy Substances 0.000 claims abstract description 11
- UMUXBDSQTCDPJZ-UHFFFAOYSA-N chromium titanium Chemical compound [Ti].[Cr] UMUXBDSQTCDPJZ-UHFFFAOYSA-N 0.000 claims abstract description 11
- 230000008030 elimination Effects 0.000 claims abstract description 8
- 238000003379 elimination reaction Methods 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims abstract description 8
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 4
- 239000011651 chromium Substances 0.000 claims abstract description 4
- -1 furnace returns Inorganic materials 0.000 claims abstract description 4
- 238000011081 inoculation Methods 0.000 claims abstract description 4
- 238000005453 pelletization Methods 0.000 claims abstract description 4
- 239000002994 raw material Substances 0.000 claims abstract description 4
- 239000010936 titanium Substances 0.000 claims abstract description 4
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 4
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 6
- 229910052717 sulfur Inorganic materials 0.000 claims description 6
- 239000011593 sulfur Substances 0.000 claims description 6
- 238000004321 preservation Methods 0.000 claims description 4
- 238000000137 annealing Methods 0.000 claims description 3
- 239000003795 chemical substances by application Substances 0.000 claims description 3
- 230000003009 desulfurizing effect Effects 0.000 claims description 3
- 238000005087 graphitization Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 239000002893 slag Substances 0.000 claims description 3
- 150000004767 nitrides Chemical class 0.000 abstract description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 3
- 210000001787 dendrite Anatomy 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910001141 Ductile iron Inorganic materials 0.000 description 1
- 229910001060 Gray iron Inorganic materials 0.000 description 1
- 241001062472 Stokellia anisodon Species 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910017464 nitrogen compound Inorganic materials 0.000 description 1
- 150000002830 nitrogen compounds Chemical class 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000007920 subcutaneous administration Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- 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
-
- 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
- C21D5/00—Heat treatments of cast-iron
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/006—Graphite
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The invention relates to the field of materials, in particular to a production method for eliminating fissured nitrogen pores of castings. The method comprises the following steps: s1, proportioning: selecting pig iron, scrap steel, furnace returns, silicon carbide, nodulizer and inoculant as raw materials; s2, smelting: pig iron, scrap steel, silicon carbide and furnace return materials are sequentially added during smelting; s2.1 elimination of nitrogen holes: adding titanium-chromium alloy after all the precursors are completely melted, wherein chromium in the titanium-chromium alloy accounts for 0.12-0.15% of all the precursors, and titanium accounts for 0.08-0.10% of all the precursors; s3, spheroidizing reaction: after the nodulizer is built by using a dam type nodulizer, covering part of inoculant on the nodulizer, and covering a fine steel sheet on the inoculant; pouring the remaining inoculant into the pelletization ladle together with the molten iron when the molten iron is discharged for one third to one half of the period; s4, pouring: pouring the molten iron in the spheroidizing ladle, and adding stream inoculation during pouring. The invention adopts a new production process, and can form nitride by utilizing the titanium-chromium alloy, so that the nitrogen content is reduced, and the purpose of eliminating slit-shaped nitrogen holes is achieved.
Description
Technical Field
The invention relates to the field of materials, in particular to a production method for eliminating fissured nitrogen pores of castings.
Background
The slit-shaped nitrogen holes are generated at the plane or the corners of the casting, are vertical to the surface of the casting, have the depth of 2-5mm (occasionally the holes are exposed out of the blank) and are not round, elliptic, water-dripping or pinhole-shaped, but are slit-shaped and clean and free of impurities in the holes unlike the common air holes.
The production reason is that the nitrogen content of the gray iron is generally (40-70) x10 -6 Proper amount of nitrogen is helpful for improving the shape of graphite, promoting pearlitic of a matrix and improving tensile strength; however, when the nitrogen content of the molten iron exceeds a certain critical value of 100x10 -6 In the latter stage of solidification, the molten iron is precipitated and surrounded by dendrite walls forming solid, so that fissured subcutaneous pores existing between dendrites are formed when the molten iron is not replenished.
The fissured nitrogen pores are not directly formed by nitrogen, because nitrogen is an inactive gas and the dissolution amount in the molten iron is less than 0.015%. The nitrogen compound is decomposed by the molten iron at high temperature to become nascent atomic nitrogen, and can be largely melted into the molten iron.
Production practice proves that the molten iron has low carbon equivalent, adopts electric furnace smelting, has high ratio of scrap steel in furnace burden and return furnace burden, and has high nitrogen content in the molten iron and large tendency of white mouth.
Disclosure of Invention
The invention aims to provide a production method for eliminating fissured nitrogen pores of a casting, which aims to solve the problem that fissured nitrogen pores are generated in the casting.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a production method for eliminating fissured nitrogen pores of castings comprises the following steps:
s1, proportioning: selecting pig iron, scrap steel, furnace returns, silicon carbide, nodulizer and inoculant as raw materials;
s2, smelting: pig iron, scrap steel, silicon carbide and furnace return materials are sequentially added during smelting; s2.1 elimination of nitrogen holes: adding titanium-chromium alloy after all the precursors are completely melted, wherein chromium in the titanium-chromium alloy accounts for 0.12-0.15% of all the precursors, and titanium accounts for 0.08-0.10% of all the precursors;
s3, spheroidizing reaction: after the nodulizer is built by using a dam type nodulizer, covering part of inoculant on the nodulizer, and covering a fine steel sheet on the inoculant; pouring the remaining inoculant into the pelletization ladle together with the molten iron when the molten iron is discharged for one third to one half of the period;
s4, pouring: pouring the molten iron in the spheroidizing ladle, and adding stream inoculation during pouring.
Preferably, the weight portion of the furnace returns is 30 to 40 percent, the scrap steel is 5 percent, the silicon carbide is 0.4 percent, the nodulizer is 1.3 percent, the inoculant is 0.6 percent, and the balance is pig iron; in the S2 smelting step, the feeding process is continuous, and the rear material is required to be added before the front material is completely melted.
Preferably, the components are detected before the S3 spheroidizing reaction, and the spheroidizing reaction is carried out when the sulfur content is lower than 0.03%; desulfurizing if the sulfur content is higher than 0.03%, spheroidizing with spheroidizing agent of 0.2-0.4% of the iron liquid mass, and returning the slag after the treatment.
Preferably, in the S3 spheroidization reaction, the amount of the part of inoculant is 30% -60% of the total inoculant.
Preferably, after the step of S4 casting, there is also S5 heat treatment: high-temperature graphitization annealing treatment is carried out, the heat preservation temperature is 780-920 ℃, and the heat preservation time is 4-8 hours.
Compared with the prior art, the invention has at least one of the following beneficial effects:
the invention adopts a new production process, and can form nitride by utilizing the titanium-chromium alloy, so that the nitrogen content is reduced, and the purpose of eliminating slit-shaped nitrogen holes is achieved.
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. The following examples are illustrative of several embodiments.
Example 1:
a production method for eliminating fissured nitrogen pores of castings comprises the following steps:
s1, proportioning: selecting pig iron, scrap steel, furnace returns, silicon carbide, nodulizer and inoculant as raw materials; according to the mass portion, the furnace return material is 30-40%, the scrap steel is 5%, the silicon carbide is 0.4%, the nodulizer is 1.3%, the inoculant is 0.6%, and the rest is pig iron;
s2, smelting: pig iron, scrap steel, silicon carbide and a furnace return material are sequentially added during smelting, the charging process is continuous, and the rear material is required to be added before the front material is completely melted; this step is an important step in the production method, and changes the mode of adding scrap steel, pig iron and return furnace materials into the prior art CN111074034A, and adding an electrolytic copper plate after the scrap steel, pig iron and return furnace materials are completely melted. On one hand, for the feeding sequence, firstly pig iron is added to smelt molten iron faster during smelting, then scrap steel is added to reduce the carbon content in molten iron, reduce the burning loss of carbon, water in a furnace is started, silicon carbide is added again to be absorbed more easily, and finally furnace materials are added back to solve the problems of shrinkage cavity and shrinkage porosity tendency caused by the excessively high content of silicon in the front of the furnace; on the other hand, the feeding is continuous in the process, the molten iron is not needed to be added after the last material is melted, the temperature of the molten iron in the furnace is not needed to exceed 1560 ℃, the process is shortened, the temperature is not needed to be increased too high, the burning loss is reduced in the whole process, and the burning loss is not reduced.
S2.1 elimination of nitrogen holes: after all the precursors are completely melted, adding titanium-chromium alloy, wherein the chromium in the titanium-chromium alloy accounts for 0.12-0.15% of all the precursors, and the titanium accounts for 0.08-0.10% of all the precursors. The titanium-chromium alloy can form nitride, so that the nitrogen content is reduced, and the aim of eliminating slit-shaped nitrogen holes is fulfilled
S3, spheroidizing reaction: before the spheroidizing reaction, firstly detecting components, and performing the spheroidizing reaction when the sulfur content is lower than 0.03%; desulfurizing if the sulfur content is higher than 0.03%, spheroidizing with spheroidizing agent of 0.2-0.4% of the iron liquid mass, and returning the slag after the treatment. After the nodulizer is built by using a dam type nodulizer, covering part of inoculant on the nodulizer, wherein the dosage is 30% -60% of the total inoculant, and covering a fine steel sheet on the inoculant; pouring the remaining inoculant into the pelletization ladle together with the molten iron when the molten iron is discharged for one third to one half of the period;
s4, pouring: pouring the molten iron in the spheroidizing ladle, and adding stream inoculation during pouring.
S5, heat treatment: performing high-temperature graphitization annealing treatment, performing ferrization on the matrix, and keeping the temperature at 780-920 ℃ for 4-8 hours.
The ductile iron castings prepared by the production process have the tensile strength and the yield strength equivalent to those of the CN111074034A embodiment through testing.
Reference in the specification to a number of illustrative embodiments means that a particular structure described in connection with the embodiments is included in at least one embodiment described generally herein. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment. Further, while a structure is described in connection with any one embodiment, it is intended that such a structure be implemented in connection with other embodiments within the scope of the invention.
Claims (5)
1. A production method for eliminating fissured nitrogen pores of castings is characterized by comprising the following steps of: the method comprises the following steps:
s1, proportioning: selecting pig iron, scrap steel, furnace returns, silicon carbide, nodulizer and inoculant as raw materials;
s2, smelting: pig iron, scrap steel, silicon carbide and furnace return materials are sequentially added during smelting; s2.1 elimination of nitrogen holes: adding titanium-chromium alloy after all the precursors are completely melted, wherein chromium in the titanium-chromium alloy accounts for 0.12-0.15% of all the precursors, and titanium accounts for 0.08-0.10% of all the precursors;
s3, spheroidizing reaction: after the nodulizer is built by using a dam type nodulizer, covering part of inoculant on the nodulizer, and covering a fine steel sheet on the inoculant; pouring the remaining inoculant into the pelletization ladle together with the molten iron when the molten iron is discharged for one third to one half of the period;
s4, pouring: pouring the molten iron in the spheroidizing ladle, and adding stream inoculation during pouring.
2. The method for producing a casting with elimination of fissured nitrogen voids according to claim 1, wherein: according to the mass portion, the furnace return material is 30-40%, the scrap steel is 5%, the silicon carbide is 0.4%, the nodulizer is 1.3%, the inoculant is 0.6%, and the rest is pig iron; in the S2 smelting step, the feeding process is continuous, and the rear material is required to be added before the front material is completely melted.
3. The method for producing a casting with elimination of fissured nitrogen voids according to claim 2, wherein: before the S3 spheroidizing reaction, firstly detecting components, and performing spheroidizing reaction when the sulfur content is lower than 0.03%; desulfurizing if the sulfur content is higher than 0.03%, spheroidizing with spheroidizing agent of 0.2-0.4% of the iron liquid mass, and returning the slag after the treatment.
4. The method for producing a casting with elimination of fissured nitrogen voids according to claim 2, wherein: in the S3 spheroidization reaction, the amount of the partial inoculant is 30-60% of the total inoculant.
5. The method for producing a casting with elimination of fissured nitrogen voids according to claim 2, wherein: after the step of S4 pouring, the heat treatment of S5 is carried out: high-temperature graphitization annealing treatment is carried out, the heat preservation temperature is 780-920 ℃, and the heat preservation time is 4-8 hours.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211358224.0A CN116411147A (en) | 2022-11-01 | 2022-11-01 | Production method for eliminating fissured nitrogen pores of castings |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211358224.0A CN116411147A (en) | 2022-11-01 | 2022-11-01 | Production method for eliminating fissured nitrogen pores of castings |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116411147A true CN116411147A (en) | 2023-07-11 |
Family
ID=87052065
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211358224.0A Pending CN116411147A (en) | 2022-11-01 | 2022-11-01 | Production method for eliminating fissured nitrogen pores of castings |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116411147A (en) |
-
2022
- 2022-11-01 CN CN202211358224.0A patent/CN116411147A/en active Pending
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