CN115505669A - Inoculant for improving tensile strength of iron casting and preparation method of inoculant - Google Patents
Inoculant for improving tensile strength of iron casting and preparation method of inoculant Download PDFInfo
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- CN115505669A CN115505669A CN202210748933.3A CN202210748933A CN115505669A CN 115505669 A CN115505669 A CN 115505669A CN 202210748933 A CN202210748933 A CN 202210748933A CN 115505669 A CN115505669 A CN 115505669A
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- 239000002054 inoculum Substances 0.000 title claims abstract description 117
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 111
- 238000005266 casting Methods 0.000 title claims abstract description 89
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 53
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 47
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 29
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 26
- 239000000956 alloy Substances 0.000 claims abstract description 26
- 239000010703 silicon Substances 0.000 claims abstract description 24
- 238000004519 manufacturing process Methods 0.000 claims abstract description 21
- 229910052788 barium Inorganic materials 0.000 claims abstract description 16
- 229910000519 Ferrosilicon Inorganic materials 0.000 claims abstract description 13
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 12
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims abstract description 11
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 9
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 7
- 239000011575 calcium Substances 0.000 claims abstract description 7
- 229910052684 Cerium Inorganic materials 0.000 claims abstract description 6
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 5
- 239000004411 aluminium Substances 0.000 claims abstract description 5
- 239000012535 impurity Substances 0.000 claims abstract description 3
- 229910052746 lanthanum Inorganic materials 0.000 claims abstract description 3
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims abstract description 3
- 229910002804 graphite Inorganic materials 0.000 claims description 37
- 239000010439 graphite Substances 0.000 claims description 37
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 24
- 238000001816 cooling Methods 0.000 claims description 22
- 238000011081 inoculation Methods 0.000 claims description 22
- 239000007788 liquid Substances 0.000 claims description 18
- 150000001875 compounds Chemical class 0.000 claims description 17
- 239000000203 mixture Substances 0.000 claims description 15
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 15
- 239000011159 matrix material Substances 0.000 claims description 13
- 239000002994 raw material Substances 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 12
- OOJQNBIDYDPHHE-UHFFFAOYSA-N barium silicon Chemical compound [Si].[Ba] OOJQNBIDYDPHHE-UHFFFAOYSA-N 0.000 claims description 9
- 229910001093 Zr alloy Inorganic materials 0.000 claims description 8
- 239000002245 particle Substances 0.000 claims description 8
- 150000002910 rare earth metals Chemical class 0.000 claims description 8
- 229910000600 Ba alloy Inorganic materials 0.000 claims description 6
- XWHPIFXRKKHEKR-UHFFFAOYSA-N iron silicon Chemical group [Si].[Fe] XWHPIFXRKKHEKR-UHFFFAOYSA-N 0.000 claims description 6
- -1 rare earth compound Chemical class 0.000 claims description 6
- 238000012216 screening Methods 0.000 claims description 6
- UVGLBOPDEUYYCS-UHFFFAOYSA-N silicon zirconium Chemical compound [Si].[Zr] UVGLBOPDEUYYCS-UHFFFAOYSA-N 0.000 claims description 6
- 229910005347 FeSi Inorganic materials 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 5
- 229910000805 Pig iron Inorganic materials 0.000 claims description 4
- 239000013078 crystal Substances 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 238000001556 precipitation Methods 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 238000003756 stirring Methods 0.000 claims description 4
- 239000000126 substance Substances 0.000 claims description 4
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims description 3
- 229910005329 FeSi 2 Inorganic materials 0.000 claims description 3
- RBZGEUJLKTVORU-UHFFFAOYSA-N 12014-84-5 Chemical compound [Ce]#[Si] RBZGEUJLKTVORU-UHFFFAOYSA-N 0.000 claims description 2
- 229910006249 ZrSi Inorganic materials 0.000 claims description 2
- TVGGZXXPVMJCCL-UHFFFAOYSA-N [Si].[La] Chemical compound [Si].[La] TVGGZXXPVMJCCL-UHFFFAOYSA-N 0.000 claims description 2
- 150000001553 barium compounds Chemical class 0.000 claims description 2
- 229940043430 calcium compound Drugs 0.000 claims description 2
- 150000001674 calcium compounds Chemical class 0.000 claims description 2
- ZMIGMASIKSOYAM-UHFFFAOYSA-N cerium Chemical compound [Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce] ZMIGMASIKSOYAM-UHFFFAOYSA-N 0.000 claims description 2
- 150000003377 silicon compounds Chemical class 0.000 claims description 2
- 150000003755 zirconium compounds Chemical class 0.000 claims description 2
- 150000002506 iron compounds Chemical class 0.000 claims 1
- 238000010079 rubber tapping Methods 0.000 claims 1
- 238000003723 Smelting Methods 0.000 abstract description 5
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 15
- 239000000047 product Substances 0.000 description 12
- 229910001060 Gray iron Inorganic materials 0.000 description 11
- 229910001141 Ductile iron Inorganic materials 0.000 description 10
- 238000009826 distribution Methods 0.000 description 9
- 238000012360 testing method Methods 0.000 description 7
- 238000001514 detection method Methods 0.000 description 6
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 5
- 229910001018 Cast iron Inorganic materials 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 4
- 238000009864 tensile test Methods 0.000 description 4
- 238000007599 discharging Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910000838 Al alloy Inorganic materials 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000003679 aging effect Effects 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 150000001552 barium Chemical class 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000013065 commercial product Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Images
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
- C21C1/10—Making spheroidal graphite cast-iron
- C21C1/105—Nodularising additive agents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
-
- 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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/006—Making ferrous alloys compositions used for making ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/08—Making cast-iron alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C35/00—Master alloys for iron or steel
Abstract
The invention relates to an inoculant for improving the tensile strength of an iron casting. The inoculant comprises, in weight percent, between 40 and 80% silicon, between 0.5 and 5% calcium, between 0 and 15% rare earths (e.g. cerium and/or lanthanum), between 0 and 10% zirconium, between 0 and 5% barium, between 0 and 5% aluminium, in a total amount not exceeding 2% by mass of impurities (including carbon, ash and other oxides in free form), the remaining mass being iron. The inoculant has fine tissue and is uniformly and dispersedly distributed. The finished product is granular ferrosilicon base alloy which is a uniform and homogeneous smelting product. The invention also relates to a production and preparation method of the inoculant.
Description
The technical field is as follows:
the invention relates to an inoculant for producing and smelting iron castings and a preparation method thereof.
The background art comprises the following steps:
the casting industry is one of the national basic industries, and products of the casting industry relate to military industry, civil use, aerospace, railways, automobiles, electric power equipment, infrastructure, various industrial and agricultural machinery manufacturing and the like. The casting parts are divided into colored casting parts and black casting parts, and the black casting parts are further divided into iron casting parts and steel casting parts. The inoculant is mainly used for iron castings.
Iron castings typically contain 2% to 4% carbon, and most of the carbon in iron castings occurs as graphite in different forms at ambient temperatures. Iron castings are subdivided into nodular cast iron, gray cast iron, vermicular cast iron, etc., according to different graphite morphologies. During the production process of the iron casting, an inoculant and an inoculation process are needed to change and adjust the existence form, distribution, size, form and the like of carbon in the iron casting, so that the performance of the iron casting is changed or improved. These properties include, but are not limited to, mechanical properties, cutting properties, natural frequency, aging properties, and the like. The addition amount of the inoculant in the production and forming process of the casting is usually 0.05-1% of the total mass of the molten iron. The addition amount is not large, but the function is very critical.
In the production process of the iron casting, a proper inoculant is added through a certain inoculation process, so that the following aims can be achieved. 1. Effectively reduce the white cast (massive Fe) 3 C tissue, also commonly referred to as carbide in the industry), thereby improving and guaranteeing the mechanical property of the casting, reducing the hardness of the casting and improving the machining performance. 2. The precipitation amount of graphite is improved or adjusted, the graphite form can be improved, the shrinkage porosity tendency in the casting forming process is reduced, the material density is improved, and then the yield of products is improved and the performance is further improved; 3. improving or adjusting the proportion of matrix structures, usually Pearlite (Pearlite) and Ferrite (Ferrite), of the castings, and further adjusting the required properties of the castings in a targeted manner; 4. improve the uniformity of casting materials, including the distribution of matrix structure and graphite. Generally, the uniformity and consistency of casting properties is also critical due to the complex structure and size of the casting product.
With the progress and development of society, the requirements of iron castings on the use of the iron castings, especially the tensile strength, are continuously increased. On the one hand, manufacturers expect castings with higher strength, including gray cast iron and nodular cast iron, to be used for parts in the same part of the main engine. For example, in a certain automobile host factory in China, the original automobile cylinder HT250 brand is required to have the actual tensile strength of 206 MPa. But recently, it has been desired by the engineers of the main foundries to assist in providing similar products with tensile strengths of up to 290 MPa. This presents a significant challenge to the foundry and, of course, the opportunity for new orders. On the other hand, in order to ensure high tensile strength, both ductile iron and gray cast iron, foundry manufacturers generally add large amounts of alloying elements, such as Cu and Sn. This directly increases the production costs of the foundry considerably. Some foundries will select Sb element to replace Cu element to improve the strength of casting indirectly. However, this has other side effects and is limited by some host plants.
Then there is no way to improve the tensile strength of the iron casting without increasing the melting cost?
The invention content is as follows:
the invention designs and develops an inoculant for improving the tensile strength of iron castings and a preparation method thereof. By the set preparation method and the use process, the inoculation effect of the inoculant can be greatly improved, and the inoculation uniformity is improved; the tensile strength of the iron casting, including gray cast iron and nodular cast iron, is improved, and the metallographic phase of the iron casting is improved. Furthermore, the method can help foundries to develop products with higher grades or reduce the addition amount of noble metals, thereby reducing the production cost.
Description of the invention creation:
according to a first aspect, the present invention relates to an inoculant for improving the tensile strength of iron castings. Wherein the inoculant is a particulate ferrosilicon-based alloy comprising, by weight, between 40 and 80% silicon, between 0.5 and 5% calcium, between 0 and 15% rare earths (e.g. cerium and/or lanthanum), between 0 and 10% zirconium, between 0 and 5% barium, between 0 and 5% aluminium, with a total of no more than 2% by mass of impurities (including carbon, ash and other oxides in free form), the remaining mass being iron.
The silicon element part in the inoculant exists in the form of a compound of silicon and iron, and mainly comprises FeSi phase and FeSi 2 Phase (1); the other part of the silicon element exists in the form of simple substance silicon. The two phases are mainly matrix phases in the product material;
the rare earth elements in the inoculant mainly exist in the form of compounds of rare earth and silicon, mainly comprise a silicon-cerium phase and a silicon-lanthanum phase, and also comprise other compound phases;
the barium element in the inoculant mainly exists in the form of a barium and silicon compound, and is mainly a silicon-barium phase;
the zirconium element in the inoculant mainly exists in the form of compounds of zirconium and silicon, and is mainly ZrSi 2 Phase (1);
the calcium element in the inoculant mainly exists in the form of a compound of calcium and silicon, and mainly exists when the calcium element is the same as the compound of a rare earth element, a barium element and a zirconium element;
the aluminum element in the inoculant mainly exists in the form of compounds of aluminum, silicon and iron and mainly exists in a matrix of an iron-silicon phase;
the iron element in the inoculant mainly exists in the form of a compound of silicon and iron, and mainly comprises FeSi phase and FeSi 2 Phase (1);
the rare earth compound phase, the barium compound phase, the zirconium compound phase, the aluminum compound phase and the calcium compound phase in the inoculant are all inoculant phases, and the precipitation of graphite in an iron casting is promoted;
in the production of the gray iron casting, the rare earth compound phase in the inoculant changes the form of the graphite sheet, reduces the cutting effect of the graphite sheet on a matrix, and can improve the tensile strength of the gray iron casting under the condition of not changing the components of the casting;
in the production of the gray iron casting, the zirconium and/or aluminum alloy phase in the inoculant improves the uniformity of graphite distribution in the iron casting, so that the graphite forms at different structures of the gray iron casting are consistent as much as possible, and the consistency of the tensile strength of different structure positions of the gray iron casting is improved;
in the production of nodular iron castings, the rare earth compound phase in the inoculant provided by the invention promotes graphite precipitation, the number of graphite spheres and the spheroidization rate are increased, and the comprehensive performance of the material of the iron castings is improved;
in the production of the nodular iron castings, the zirconium and/or aluminum alloy phase in the inoculant disclosed by the invention improves the uniformity of graphite distribution in the iron castings, so that the graphite forms at different structures of the nodular iron castings are consistent as much as possible, and the tensile strength of the nodular iron castings can be further improved;
in the production of gray iron pieces and nodular iron pieces, the combined phase of barium in the inoculant improves the timeliness of inoculation. The casting process for the production of iron castings varies from 2 minutes to 30 minutes, and the number of casting flasks varies from 1 to several tens of flasks. The difference of the inoculation performances of the first box casting and the last box casting can be reduced by the compound phase of barium, so that the consistency of the integral finished product of the iron casting is improved;
according to a preferred embodiment, the various phase structure refinements in the inoculant according to the invention, including the matrix phase and the inoculant phase, are distributed uniformly, as shown in fig. 2 and 3. Compared with the existing products on the market, the number of the 'crystal grains' formed under the unit area of the inoculant disclosed by the invention is increased by 1-2 orders of magnitude, and the distribution of phases is more dispersed and uniform. The inoculated phase is distributed in block, lamellar and granular shapes, and as shown in figure 1, the light (white) color phase is the inoculated phase. Wherein the size of the inoculation phase 'crystal grains' is 5-50 μm, and the size of the block inoculation phases is 20-50 μm; the granular and flaky inoculation phases are both 5-10 mu m, and the distribution of the inoculation element phases is similar to that of graphite in an iron casting, and the inoculation element phases are uniform and dispersed. At a magnification of 100, at 1mm 2 In the area, the number of 'grains' of the inoculation element phase reaches more than 500. In addition, the matrix phase is dark, wherein grey is an iron silicon phase and dark grey is an elemental silicon phase.
According to verification, compared with the conventional inoculant, the produced inoculant has the advantages that under the same casting using condition, the casting comprehensive performance is better, the tensile strength is higher, and the casting uniformity is better.
The second aspect relates to a method for producing the inoculant for cast iron of the present invention.
Step one, selecting high-grade ferrosilicon and pig iron as raw materials, uniformly mixing the raw materials according to a certain mass percentage, simultaneously placing the raw materials in an intermediate frequency furnace for smelting to 1300-1350 ℃, wherein the alloy in the furnace is a completely-molten and uniform liquid alloy liquid, and simultaneously removing scum. Then adding the silicon-barium alloy and the silicon-zirconium alloy into the melting furnace according to a certain proportion and sequence, rapidly heating to 30-100 ℃, uniformly stirring to form molten iron, and keeping the temperature of the metal liquid in the furnace at about 1400 ℃ (± 20 ℃). In the process of discharging, the rare earth silicon iron alloy particles are uniformly sprinkled on the alloy liquid in a flowing mode. In the preparation process, the mass percentage of the silicon-zirconium alloy is within the range of 10-30%, and the granularity is 10-70mm; the mass percentage of the silicon-barium alloy is 5-15%, and the granularity is 10-70mm; the weight percentage of the rare earth ferrosilicon is 10-30%, and the granularity is 1-5mm.
And step two, cooling, solidifying, crushing and screening. And cooling the alloy liquid to a solid state (below 900 ℃) by a rapid cooling device, wherein the cooling speed is more than 50 ℃/s. And then placing the mixture in a graphite container to naturally cool the mixture to room temperature. Finally crushing and screening to obtain the granular inoculant with different granularity specifications.
Description of the drawings:
FIG. 1 shows the results of comparative example I 1 A plane Scanning Electron Microscope (SEM) gold phase image of the inoculant is magnified by 100 times by using a back scattering electron image;
FIG. 2 shows I of example 1 2 A plane Scanning Electron Microscope (SEM) metallographic image of the inoculant is magnified by 100 times by using a back scattering electron image;
FIG. 3 shows I of example 2 3 A plane Scanning Electron Microscope (SEM) metallographic image of the inoculant is magnified by 500 times by using a back scattering electron image;
FIG. 4 is a pictorial view of an automotive engine block member;
FIG. 5 shows the use of comparative example I 1 The optical metallographic phase of the hot junction part of the inoculant production cylinder is enlarged by 100 times;
FIG. 6 shows the use of I of example 1 2 The optical metallographic phase of the hot junction part of the inoculant production cylinder is enlarged by 100 times;
FIG. 7 shows the use of comparative example I 1 The fracture Scanning Electron Microscope (SEM) image of the inoculant production cylinder tensile test bar is enlarged by 100 times;
FIG. 8 shows the use of I of example 1 2 A fracture Scanning Electron Microscope (SEM) image of the inoculant production cylinder tensile test rod is magnified by 100 times;
FIG. 9 is a pictorial view of an automotive crankshaft iron casting;
FIG. 10 shows the use of comparative example I 1 Optical metallographic phase magnification of 100 times for large end of crankshaft produced by inoculant
FIG. 11 shows the use of I of example 2 3 The optical metallographic phase of the large end of the crankshaft produced by the inoculant is amplified by 100 times;
the specific implementation mode is as follows:
comparative example
The inoculants conventionally used on the market were used as comparative examples: silicon-barium series inoculant, and the main components of the producing area, namely inner Mongolia of China: 71.4% Si,4.87% Ba,1.54% Ca,1-6mm, as shown in Table 1.
TABLE 1 inoculant information for comparison
| Comparison of | Producing area | Main chemical components of inoculant | Cooling method | Number of | Comparison of |
| Comparative example | Inner Mongolia | 71.4％Si,4.87％Ba,1.54％Ca | Ingot disc natural cooling | I 1 | Market technology |
| Example 1 | (Hubei) | 51.2％Si,4.78％Zr,2.3％Ba,7.8％Ce | High speed cooling | I 2 | The invention relates to |
| Example 2 | (Hubei) | 50.7％Si,7.23％Zr,2.41％Ba,4.15％Ce | High speed cooling | I 3 | The invention relates to |
Example 1
Production of inoculant
Selecting high-grade ferrosilicon and pig iron as raw materials, uniformly mixing the raw materials according to the mass percentage of 80 percent, simultaneously placing the raw materials in an intermediate frequency furnace for smelting to 1300-1350 ℃, and simultaneously removing scum, wherein the alloy in the furnace is in a completely and uniformly molten liquid alloy liquid. Then sequentially adding the high-grade silicon-barium alloy (10-70 mm) and the silicon-zirconium alloy (10-70 mm) into a melting furnace according to 10 percent and 15 percent of the total mass percent, quickly heating to 30-100 ℃, uniformly stirring to form molten iron, and keeping the temperature of the metal liquid in the furnace at about 1400 ℃ (± 20 ℃). In the process of discharging, 1-5mm rare earth ferrosilicon alloy particles are uniformly sprinkled on the alloy liquid in a flowing mode according to the proportion of 25%.
Cooling, solidifying, crushing and sieving. And cooling the alloy liquid to a solid state (below 900 ℃) by a rapid cooling device, wherein the cooling speed is more than 50 ℃/second. And then placing the mixture in a graphite container to naturally cool the mixture to room temperature. Finally crushing and screening to obtain granular inoculant I with the grain size of 1-6mm 2 . Actually measured components: 51.2% Si,4.78% Zr,2.3% Ba,7.8% Ce,1.01Ca%,0.87% Al. Specific information is shown in table 1.
Example 2
Production of inoculant
Selecting high-grade ferrosilicon and pig iron as raw materials, uniformly mixing the raw materials according to the mass percentage of 80 to 20, simultaneously placing the raw materials in an intermediate frequency furnace, smelting the mixture to 1300-1350 ℃, and simultaneously removing scum, wherein the alloy in the furnace is a completely-molten and uniform liquid alloy liquid. Then sequentially adding the high-grade silicon-barium alloy (10-70 mm) and the silicon-zirconium alloy (10-70 mm) into the melting furnace according to 10 percent and 30 percent of the total mass percent, rapidly heating to 30-100 ℃, uniformly stirring to form molten iron, and cooling to about 1400 ℃ (± 20 ℃) of the metal temperature in the furnace. In the process of discharging, 1-5mm rare earth ferrosilicon alloy particles are uniformly sprinkled on the alloy liquid in a flowing mode according to the proportion of 15%.
Cooling, solidifying, crushing and sieving. And cooling the alloy liquid to a solid state (below 900 ℃) by a rapid cooling device, wherein the cooling speed is more than 50 ℃/second. Then placing the mixture in a graphite container for natural cooling toAnd (4) room temperature. Finally crushing and screening to obtain granular inoculant I with the grain size of 1-6mm 3 . Actually measured components: 50.7% of Si,7.23% of Zr,2.41% of Ba,4.15% of Ce,1.13Ca%,0.85% of Al. Specific information is shown in table 1.
Example 3
Inoculant comparison
Selecting I of comparative example 1 Inoculant and I of examples 1 and 2 2 Inoculants and I 3 Large-particle alloy of the inoculant is inlaid into a metallographic test block, and an observation plane is ground. The comparison was observed using a Scanning Electron Microscope (SEM) using the component phases of the backscattered electron light source of the SEM. I.C. A 1 The inoculant is shown in figure 1, wherein the dark gray phase is a simple substance silicon phase, the light gray phase is an iron-silicon compound phase, and the white (bright) phase is an inoculating element compound phase.
Inoculant I 2 And inoculant I 3 As shown in figures 2 and 3, the various phase structures are refined, including a matrix phase and an inoculation phase, and are uniformly distributed. Compared with the existing commercial product I 1 The inoculant provided by the invention has the advantages that the number of 'grains' formed in unit area of the inoculant is increased by 1-2 orders of magnitude, and the distribution of phases is more dispersed and uniform. The inoculation phase is distributed in a block shape, a lamellar shape and a granular shape, and a light (white) color phase is the inoculation phase as shown in figure 1. Wherein the size of the 'crystal grains' of the inoculation phase is 5-50 mu m, and the sizes of the blocky inoculation phases are 20-50 mu m; the granular and flaky inoculating phases are both 5-10 mu m, and the inoculating element phase distribution is similar to the graphite distribution in iron castings, and is uniform and dispersed. At a magnification of 100, at 1mm 2 In the area, the number of 'grains' of the inoculation element phase reaches more than 500. In addition, the matrix phase is dark, wherein grey is an iron silicon phase and dark grey is an elemental silicon phase.
Example 4
Inoculant application 1
TABLE 2 composition of cast iron parts of automobile cylinder
| C | Si | Mn | P | S | Cr | Cu | Sn | |
| Stokehole hot metal | 3.35 | 1.58 | 0.55 | 0.02 | 0.088 | 0.22 | 0.48 | 0.069 |
| Molten iron after furnace | 3.34 | 1.82 | 0.54 | 0.02 | 0.076 | 0.22 | 0.48 | 0.0655 |
Comparative example I was used 1 Inoculant and I of example 1 2 Inoculants were compared on gray cast iron castings of automobile engine cylinders. Fig. 4 is a diagram of an engine block, in which a hot junction portion is provided at a red square frame, and a metallographic detection is required. The composition of the cast product before and after the furnace is shown in Table 2. Using conventional inoculants, i.e. comparative example I 1 The inoculant is used as an in-ladle inoculant, the addition amount is 0.4%, and the metallographic phase of the hot junction part of the obtained casting is shown in figure 5, and the obtained casting contains chrysanthemum-shaped graphite (C-type graphite). The local scanning electron microscope observation of the fracture of the cast tensile test bar is shown in figure 7, and the test bar is easy to fracture from the graphite part completely. The tensile strength and hardness of the test bars are shown in Table 3.
Using the inoculant described in the present invention, i.e. I of example 1 2 The inoculant is used as ladle inoculant, the addition amount is 0.4%, the metallographic phase of the hot junction part of the obtained casting is shown in figure 6, chrysanthemum-shaped graphite disappears, and the graphite length is clearThe graphite bending is obviously increased. The local scanning electron microscope observation of the fracture of the cast tensile test bar is shown in FIG. 8. The tensile strength and hardness of the test bars, and the metallographic phase of the hot-bonded part are shown in Table 3.
TABLE 3 representation of inoculants on automotive cylinder iron castings
| Comparison of | Tensile strength | Hardness of | Graphite type | Maximum graphite length | Average graphite length | Number of | Comparison of |
| Comparative example | 235MPa | 223HB | A+B+C | 1100μm | 54μm | I 1 | Market technology |
| Example 1 | 287MPa | 228HB | A | 310μm | 33μm | I 2 | The invention relates to |
From the actual detection result, the inoculant I provided by the invention 2 The overall performance was superior to the commercial inoculants as shown in table 3. Under the same molten iron composition and the same casting process, the tensile strength of the iron casting is improved by 22 percent. Coarse graphite and chrysanthemum-like graphite in the hot junction portion disappeared, and the average graphite length decreased.
In fact, the casting test results taught by the present invention are one example of a statistical average representing the unit volume of automotive cylinder parts. When the unit uses the product, the tensile strength of the automobile cylinder body casting is improved by 40-60MPa. Meanwhile, coarse graphite at a hot junction part on the cylinder body is eliminated, and pits on a processing surface disappear.
Example 5
Inoculant application 2
TABLE 4 composition of cast iron parts of automotive crankshafts
| Composition (I) | C | Si | Mn | P | S | Cr | Sn | Cu | Ti | Mg |
| In front of furnace | 3.79 | 1.565 | 0.688 | 0.023 | 0.01 | 0.058 | 0.002 | 0.389 | 0.006 | 0.003 |
| After the furnace | 3.68 | 2.192 | 0.713 | 0.023 | 0.007 | 0.058 | 0.003 | 0.36 | 0.007 | 0.035 |
Comparative example I was used 1 Inoculant and I of example 2 3 Inoculants were compared on ductile iron castings of automobile crankshafts. The single weight of the casting is 23Kg, and the performance required by manufacturers reaches 600-4, namely the tensile strength is more than 600MPa, and the elongation is more than 4%. FIG. 9 is a diagram of an automotive crankshaft showing the locations identified for metallographic examination and performance stretching. The common inoculant, namely the inoculant in the comparative example, is used before the casting, the tensile strength of the casting is lower, the metallographic phase of the large head end (namely the position of metallographic detection 1) of the crankshaft casting is unqualified, and the number of graphite balls is smaller. The composition of the cast product before and after the furnace is shown in Table 4. Using conventional inoculants, i.e. comparative example I 1 The inoculant is used as an in-ladle inoculant, the addition amount is 0.3%, the metallographic phase at the position of the metallographic phase detection point 1 is obtained as shown in a figure 10, the number of graphite spheres is small, and the nodularity is low.
Use of the inoculant described in the present invention, i.e. I of example 2 3 The inoculant is used as an in-ladle inoculant, the addition amount is 0.3%, the metallographic phase of the large-head end (namely the position of metallographic phase detection 1) of the crankshaft casting is obtained as shown in a figure 11, the number of graphite spheres is obviously increased, the nodularity is improved by more than 1 time, and the nodularity is also improved. The mechanical properties of the castings were measured as shown in Table 5.
TABLE 5 representation of inoculants on automotive crankshaft iron castings
| Comparison of | Number of graphite balls | Nodularity of spheroidization | Tensile strength | Yield strength | Elongation percentage | Hardness of | Number of | Comparison of |
| Comparative example | 73 | 77％ | 660MPa | 395MPa | 4.36％ | 227 | I 1 | Prior Art |
| Example 2 | 217 | 93％ | 732MPa | 435MPa | 7.14％ | 225 | I 3 | The invention relates to |
From the actual detection result, the inoculant I provided by the invention 3 The overall performance is superior to the prior inoculants on the market. Under the same molten iron composition and the same casting process, the tensile strength of the iron casting is improved by 11 percent. The number of graphite balls at the big end of the crankshaft and the nodularity are obviously increased, and the number of the graphite balls is improved by 197 percent. In addition, the elongation of the cast test bar is obviously improved.
The casting test results taught by the present invention are an example of a statistical average representing the crankshaft parts of this unit of mass produced automobile. When the unit uses the product, the tensile strength of the automobile cylinder body casting is improved by 50-70MPa. Meanwhile, the metallographic result of the big end of the crankshaft is qualified.
Claims (15)
1. An inoculant for improving the tensile strength of iron castings, comprising, in weight percentages, between 40 and 80% silicon, between 0.5 and 5% calcium, between 0 and 15% rare earths (for example cerium and/or lanthanum), between 0 and 10% zirconium, between 0 and 5% barium, between 0 and 5% aluminium, a total of impurities (including carbon, ash and other oxides in free form) not exceeding 2% by mass, the remaining mass being iron.
2. The inoculant according to claim 1, wherein the inoculant is a granular ferrosilicon based alloy that is a homogeneous melt product.
3. The inoculant as claimed in claim 1-2, wherein the silicon part of the inoculant is in the form of a compound of silicon and iron, mainly comprising FeSi phase and FeSi 2 Phase (1); the other part of the silicon element exists in the form of simple substance silicon, and the two phases are mainly matrix phases in the product material.
4. The inoculant according to claims 1 to 3, wherein the rare earth elements are present mainly as compounds of rare earth and silicon, mainly as cerium-silicon phases and lanthanum-silicon phases, and further comprising other forms of compounds.
5. The inoculant according to claims 1-4, wherein the barium element in the inoculant is present mainly as a barium and silicon compound, mainly as a silicon-barium phase.
6. The inoculant as claimed in claims 1 to 5, wherein the zirconium element in the inoculant is mainly present as a compound of zirconium and silicon, mainly ZrSi 2 And (4) phase(s).
7. The inoculant according to claims 1 to 6, wherein the calcium element is present mainly as a compound of calcium and silicon, mainly as a compound of the rare earths, barium and zirconium elements.
8. The inoculant according to claims 1 to 7, wherein the aluminium element is present mainly in the form of aluminium, silicon, iron compounds, mainly in the matrix of the ferrosilicon phase.
9. The inoculant as claimed in claims 1 to 8, wherein the iron element in the inoculant is present mainly as a compound of silicon and iron, mainly comprising a FeSi phase and a FeSi phase 2 And (4) phase.
10. The inoculant according to claims 1 to 9, wherein the rare earth compound phases, the barium compound phases, the zirconium compound phases, the aluminum compound phases and the calcium compound phases in the inoculant are all inoculant phases, and the precipitation of graphite in the iron casting is promoted.
11. The inoculant of claims 1 to 10, wherein the phases in the inoculant are refined in structure, including a matrix phase and an inoculant phase, and are uniformly distributed, as shown in figures 2 and 3, compared with the existing commercial products, the number of formed 'grains' in unit area of the inoculant disclosed by the invention is increased by 1 to 2 orders of magnitude, the phases are more dispersed and uniform, and the inoculant phases are distributed in blocks, layers and particles; as shown in fig. 2 and 3, the light (white) phase is the inoculation phase: wherein the size of the inoculation phase 'crystal grains' is 5-50 μm, and the size of the block inoculation phases is 20-50 μm; the granular and flaky inoculating phases are all 5-10 μm, and the inoculating element phase is distributed like graphite in iron casting, and is uniform and dispersed under 100 times of magnification and 1mm 2 In the area, the number of 'grains' of the inoculation element phase reaches more than 500, in addition, the matrix phase is dark color, wherein the gray color is an iron-silicon phase, and the dark gray color is an elemental silicon phase.
12. A method for producing an inoculant for improving the tensile strength of iron castings, including but not limited to the inoculant of claims 1-11.
13. The method of claim 12, wherein the alloy is melted by selecting high-grade ferrosilicon and pig iron as raw materials, uniformly mixing the raw materials according to a certain mass percent, then putting the raw materials into an intermediate frequency furnace to melt the raw materials to 1300-1350 ℃, wherein the alloy in the furnace is in a completely molten and uniform liquid alloy liquid, simultaneously skimming scum, then sequentially adding the silicon-barium alloy and the silicon-zirconium alloy into the furnace according to a certain proportion and sequence, then rapidly heating the mixture to 30-100 ℃, uniformly stirring the mixture to form molten iron liquid, and during the preparation process, the mass percent of the silicon-zirconium alloy is in the range of 10-30%, and the particle size is 10-70mm; the silicon-barium alloy has the mass percentage in the range of 5-15% and the granularity in the range of 10-70mm.
14. The method of claim 12 to 13, wherein during tapping, the rare earth ferrosilicon alloy particles are uniformly sprinkled on the alloy liquid in a flow-following manner, the rare earth ferrosilicon being in the range of 10 to 30% by mass and having a particle size of 1 to 5mm.
15. The method of claims 12-14, cooling to solidify the inoculant melt, crushing and screening the finished inoculant product, cooling the molten alloy to a solid state (below 900 ℃) at a cooling rate of greater than 50 ℃/sec using a rapid cooling device, placing the molten alloy in a graphite container to cool naturally to room temperature, and finally crushing and screening the molten alloy to form granular inoculants of different grain sizes.
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| CN116441496A (en) * | 2023-03-28 | 2023-07-18 | 内蒙古科利源新材料有限公司 | Efficient inoculant containing bismuth oxide for large-section ductile iron castings and preparation method thereof |
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| CN116441496A (en) * | 2023-03-28 | 2023-07-18 | 内蒙古科利源新材料有限公司 | Efficient inoculant containing bismuth oxide for large-section ductile iron castings and preparation method thereof |
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