Metalworking additives
A novel inoculant composition with zirconium, bismuth, or barium as activators addresses mixing challenges in molten iron treatment, achieving high-quality castings at lower costs by optimizing mixing efficiency and reducing additive rates.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- FOSECO INTERNATIONAL LTD
- Filing Date
- 2024-04-05
- Publication Date
- 2026-05-07
AI Technical Summary
Existing inoculant compositions for molten iron face challenges in achieving adequate mixing and distribution due to low addition rates, leading to inadequate inoculation and costly casting defects, while high addition rates increase manufacturing costs.
A novel inoculant composition comprising 10-90% by weight of an activator, primarily zirconium, bismuth, or barium, with a carrier like ferrosilicon, and optional secondary components, allowing for lower addition rates of 0.5% by weight or less, improving mixing efficiency and reducing costs.
The new composition achieves high-quality castings with reduced additive rates, enhancing mixing and reducing manufacturing costs without compromising inoculation quality.
Smart Images
Figure 2026514215000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for treating molten metal. In particular, the present invention relates to the treatment of molten iron, as well as systems and compositions for treating molten iron.
Background Art
[0002] Metal treatment agents are used to modify the composition, morphology, and / or distribution of graphite particles found in molten iron. Metal treatment agents applied to molten iron include nodularising agents and inoculants that change the morphology of the iron structure and are thereby used to produce ductile iron (DI) and compact graphite iron (CGI). An inoculant is an additive that introduces nuclei into molten iron and acts as a crystallization point for carbon dissolved in the molten iron, and these crystallization points change the precipitation of graphite and the formation of the structure of the casting. Insufficient inoculation leads to the formation of undesirable iron carbides in the casting when the iron cools.
[0003] Many alloys of existing inoculants are based on ferrosilicon as a carrier and are alloys to which "active agents" such as calcium, aluminum, barium, zirconium, strontium, rare earth metals, etc. are added. During the inoculation of molten cast iron, the oxygen and / or sulfur contained therein bind entirely or partially to the active agents in the inoculant composition and crystallize as oxides, sulfides, or oxysulfides, etc. These ultramicroscopic chemical compounds / crystallizations act as crystal nuclei for the crystallization of graphite particles in the solidifying cast iron. The inoculant composition itself is provided as a powder material or a granular material having particles with an average size ranging from 0.2 mm to 15 mm or less.
[0004] In a typical inoculation process, the amount of inoculant composition required is very small. For example, even with a relatively high addition rate of 0.4-0.5% by weight of the inoculant composition relative to the weight of the iron being processed, this amounts to only 4-5 kg per metric tonne of metal. Furthermore, conventional inoculant compositions have an activator concentration of approximately 5%, which corresponds to an addition rate of approximately 250 g of activator per metric tonne of iron. In addition, to keep costs low, it is desirable to use the minimum weight of material. However, such low addition rates present significant problems when mixing the inoculant into the molten iron. For example, the inoculant may be supplied into the ladle before the molten iron is poured into it. If the weight / volume of the inoculant composition is small, if some of the powder remains in the corners of the ladle during processing, the entire volume of the ladle may be inadequately inoculated. In the case of in-stream inoculation, small amounts of inoculant are difficult to control, and if not all of the inoculant enters the flow of metal, inadequate inoculation will result.
[0005] Insufficient inoculation (e.g., as a result of poor mixing) leads to poor crystalline structure formation and costly casting defects. To improve mixing, inoculants are typically 90% ferrosilicon-based, with ferrosilicon acting as a soluble carrier. That is, the active ingredient in such a ferrosilicon-based inoculant only needs to account for 10% of the total weight or volume of the inoculant composition. A lower concentration of the composition means that a larger amount of composition is needed, but this leads to a larger tolerance for error and improved mixing of the molten material. However, this increases the costs of manufacturing, transporting, and using the inoculant composition.
[0006] Therefore, it is desirable to provide alternative inoculant compositions that mitigate or improve one or more problems related to existing inoculant compositions and inoculation processes. [Overview of the project]
[0007] According to a first aspect of the present invention, an inoculant composition for treating molten iron is provided. The inoculant composition may contain 10 to 90% by weight of an activator. The inoculant composition may contain 90 to 10% by weight of a carrier. The activator may contain one or more of barium, bismuth, manganese, and zirconium as main components. The inoculant composition may contain less than 0.5% by weight of magnesium.
[0008] As used herein, the term “primary component” refers to the element or compound having the highest addition rate, e.g., the highest weight percentage, within the activator. The activator may contain one or more additional components. Iron and silicon are not considered activators, either individually or as a ferrosilicon alloy.
[0009] All weight percentages used herein are based on the whole inoculum composition unless otherwise specified.
[0010] The activator may contain 3-40% by weight of zirconium (relative to the total weight of the inoculant composition).
[0011] The activator may contain at least 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, or 38% by weight of zirconium. The activator may contain 38, 36, 35, 34, 32, 30, 28, 26, 25, 24, 22, 20, 18, 16, 15, 14, 12, 10, 9, 8, 7, 6, 5, or less than 4% by weight of zirconium.
[0012] In some embodiments, the activator contains 3 to 25% by weight of zirconium. For example, in some embodiments, the activator contains 4 to 6% by weight, 8 to 15% by weight, 10 to 12% by weight, or 18 to 22% by weight of zirconium. In a further series of embodiments, the activator contains 25 to 40% by weight, optionally 30 to 35% by weight of zirconium.
[0013] The activator may contain 3 to 25% by weight of bismuth (relative to the total weight of the inoculant composition). The activator may contain at least 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, or 24% by weight of bismuth. The activator may contain less than 24, 22, 20, 18, 16, 15, 14, 12, 10, 9, 8, 7, 6, 5, or 4% by weight of bismuth. In some embodiments, the activator contains 4 to 6% by weight, or 5 to 15% by weight of bismuth.
[0014] The activator may contain 5-40% by weight of barium (relative to the total weight of the inoculant composition). The activator may contain at least 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, or 38% by weight of barium. The activator may contain at least 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, or 38% by weight of barium. The activator may contain less than 38, 36, 35, 34, 32, 30, 28, 26, 25, 24, 22, 20, 18, 16, 15, 14, 12, 10, 9, 8, 7, or 6% by weight of barium. In some embodiments, the activator comprises 5-15% by weight of barium, or 10-12% by weight of barium. In some further embodiments, the activator comprises 30-40% by weight of barium, for example, 34-36% by weight or 35% by weight of barium.
[0015] The inoculant composition may contain secondary activators and / or secondary components. In some embodiments, the inoculant composition contains multiple activators. As described above, the main component is the activator that has the largest addition rate to the inoculant composition. Therefore, secondary activators provide additional inoculant effects.
[0016] Secondary components may include compounds or materials that do not have an inoculant effect, and / or compounds or materials selected for other useful properties or effects on the inoculant composition.
[0017] The activator may further contain 0 to 10% by weight of calcium (relative to the total weight of the inoculant composition). The activator may contain at least 0.2, 0.3, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, or 9% by weight of calcium. The activator may contain less than 9, 8, 7, 6, 5, 4, 3, 2, 1.5, 1, 0.5, 0.3, or 0.2% by weight of calcium. In some embodiments, the activator contains 0 to 5% by weight, optionally 0.5 to 2% by weight of calcium. In some embodiments, the activator contains 1 to 7% by weight, optionally 1 to 2% by weight of calcium. Calcium may be present as a secondary activator or secondary component.
[0018] The activator may further contain 0 to 5% by weight of aluminum. The activator may contain at least 0.5, 1, 1.5, 2, 3, or 4% by weight of aluminum. The activator may contain less than 4, 3, 2, 1.5, 1, or 0.5% by weight of aluminum. In some embodiments, the activator contains 1 to 2% by weight of aluminum. In some embodiments, the activator may contain 1.5% by weight or less of aluminum. Aluminum may be present as a secondary activator or secondary component.
[0019] In some embodiments, aluminum and / or calcium may originate from other mineral or component inclusions. For example, aluminum and / or calcium are often found in barium and other, particularly natural, mineral sources. In some embodiments, additional aluminum or calcium may be added to the inoculant composition in amounts exceeding those naturally present in the other components.
[0020] The inoculant composition may contain 0 to 22% by weight of manganese (relative to the total weight of the inoculant composition). The inoculant composition may contain at least 0.2, 0.3, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, or 19% by weight of manganese. The inoculant composition may contain less than 19, 18, 16, 15, 14, 12, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1.5, 1, 0.5, 0.3, or 0.2% by weight of manganese. In some embodiments, the inoculant composition contains 0.3 to 20% by weight, 0.3 to 15% by weight, or 10 to 12% by weight of manganese. Manganese may be present as a secondary component. Manganese is effective in lowering the melting point of the inoculant composition alloy and therefore improves the processing process.
[0021] In a series of embodiments (which can be combined with the above), the activator comprises 8-15% by weight of zirconium and 0.3-15% by weight of manganese. In a further series of embodiments, the activator comprises 25-40% by weight of zirconium and 0.3-20% by weight of manganese. In some embodiments, the activator comprises 1.5% by weight or less of aluminum. Alloys of zirconium, such as alloys with manganese or other metals, are particularly desirable due to the low solubility of zirconium in molten iron.
[0022] In a series of embodiments (which can be combined with the above), the activator comprises 3 to 25% by weight of zirconium and 3 to 25% by weight of bismuth. For example, the activator may comprise 4 to 6% by weight of zirconium and 4 to 6% by weight of bismuth. The activator may optionally comprise 0 to 5% by weight of manganese. The activator may comprise 0 to 5% by weight of aluminum and optionally 1 to 2% by weight of aluminum. In some embodiments, the activator comprises 18 to 22% by weight of zirconium and 5 to 15% by weight of bismuth. The activator may comprise 0 to 22% by weight of manganese. The activator may comprise 0 to 5% by weight of aluminum and optionally 1 to 2% by weight of aluminum.
[0023] In a series of embodiments (which can be combined with the above), the activator comprises 20-40% by weight of barium and 0-10% by weight of calcium. In some embodiments, the activator comprises 30-35% by weight of barium and 1-6% by weight of calcium. In some embodiments, the activator comprises 1.5% by weight or less of aluminum.
[0024] The inoculant composition may contain less than 0.5% by weight of carbon, less than 0.1% by weight of sulfur, and / or less than 0.5% by weight of phosphorus.
[0025] The carrier may contain iron, silicon, and / or ferrosilicon. The carrier may contain 10 to 70% by weight of silicon (relative to the total weight of the inoculant composition) as silicon or ferrosilicon. The carrier may contain at least 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, or 65% by weight of silicon. The carrier may contain less than 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, or 15% by weight of silicon. In some embodiments, the carrier contains 10 to 20% by weight of silicon. In some embodiments, the carrier contains 45 to 60% by weight of silicon.
[0026] The remainder of the inoculant composition may contain iron or iron as ferrosilicon. In some embodiments, the carrier contains 18 to 85% by weight of iron. The carrier may contain at least 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80% by weight of iron. The carrier may contain 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, or less than 15% by weight of iron. In some embodiments, the carrier contains 19 to 50% by weight of iron, 30 to 55% by weight of iron, or 24 to 85% by weight of iron.
[0027] In embodiments containing ferrosilicon, the ferrosilicon contains 50 - 70% silicon, preferably 60 - 70% silicon. These alloys are advantageous because they have the lowest melting point among ferrosilicon alloys, which is about 1100 °C. Since cast iron requires a small amount of silicon therein, the silicon content usually does not pose a problem as long as it is maintained within the limited range. An excessive addition of silicon may lead to the problem of re-melting of iron.
[0028] The inoculant composition can be formed as a single alloy containing all the components.
[0029] The inoculant composition can be formed into powders, granules, and / or tablets. In some embodiments, the inoculant composition is provided in pre-portioned packages. The pre-portioned packages can contain powders, granules, and / or tablets. The pre-portioned packages are made of paper or card material, metal foil, and / or plastic material and contain the inoculant composition.
[0030] In some embodiments, the inoculant composition is supplied within a cored wire. The wire may include an outer tube of iron or steel containing the inoculant composition.
[0031] The inoculant composition can contain particles or grains sized from 0.2 mm to 12 mm. For example, the inoculant composition can contain 90% particles or grains within the range of 0.2 mm to 12 mm. In some embodiments, the particle size can be 0.2 - 0.7 mm. Such fine particles are desirable for use in an in-stream inoculation system. In some embodiments, the particles or grains can include those of 0.2 - 2 mm, 2 - 6 mm, and / or 6 - 12 mm.
[0032] A second aspect of the present invention provides a method for inoculating molten iron. The method may include supplying an inoculant composition described herein into a vessel. The method may include adding molten iron to the vessel. The vessel may be a transfer ladle. The method may include adding an inoculant composition in an amount of 0.5% by weight or less relative to the weight of the molten iron to be processed. In some embodiments, the method includes adding the inoculant composition in amounts of less than 0.45% by weight, less than 0.4% by weight, less than 0.35% by weight, 0.3, 0.25, 0.2, 0.15, 0.1, 0.8, 0.6, 0.5, 0.4, 0.2, 0.1, 0.08, 0.06, 0.05, 0.04, or 0.02% by weight relative to the weight of the molten iron.
[0033] The inventors have found that the present invention can inoculate molten iron and supply high-quality castings even at much lower additive rates. Significant cost reductions can be achieved by reducing the amount of inoculant composition required to inoculate the molten iron. Although the inoculant composition itself has a high manufacturing cost, the low additive rate allows foundries to improve cost efficiency while maintaining high quality.
[0034] In some embodiments, the method may include stirring the molten iron using, for example, a rotor. In some embodiments, the method may include supplying the molten iron to the inoculant composition through the rotor.
[0035] A third aspect of the present invention provides a method for inoculating molten iron, comprising spraying an inoculant composition described herein into a flow of molten iron. The method may include spraying an inoculant composition into a flow of molten metal between a conveying ladle and a mold.
[0036] A fourth aspect of the present invention provides a method for producing the inoculant composition described herein. The method may include reacting silica, iron, and carbon in a submerged arc furnace to form ferrosilicon and carbon dioxide, or remelting a ferrosilicon alloy in an induction furnace. The method may include adding one or more activators to the furnace to form an alloyed inoculant composition comprising a carrier and activators. The method may include cooling and solidifying the inoculant composition. The method may include grinding the inoculant composition to produce a granular and / or powdered inoculant composition.
[0037] The method may include grinding the inoculant composition to a particle size and / or grain size within the range of 0.2 mm to 12 mm, or the range described above. The method may also include removing particles smaller than 0.2 mm.
[0038] The method may further include mixing a granular and / or powdered inoculant composition with a further granular and / or powdered activator. The method may also include mixing a granular and / or powdered inoculant composition with a further carrier. [Brief explanation of the drawing]
[0039] [Figure 1] [Figure 2] [Modes for carrying out the invention]
[0040] Embodiments of the present invention will be described with reference to the following experimental data.
[0041] <Experiment - Casting Test> Several powdered inoculant compositions E1 to E5 were prepared as shown in Table 1.
[0042] [Table 1]
[0043] In a series of tests, each of E1 to E5 was weighed to a predetermined weight, wrapped in aluminum foil, and formed pre-divided packages. These pre-divided packages were added to the top of a transport pot filled with 360 kg of molten iron. The addition rates of E1 to E5 ranged from 0.23% to 0.06% by weight of the molten iron. As a comparative example, 0.7% by weight of C1 was added to a transport pot containing 360 kg of molten iron. The inoculated iron was then poured into a mold and cooled.
[0044] Tests using compositions E1, E2, and E5 showed that zirconium had an excellent recovery rate of 60% to 70%. Metal "recovery" is the amount present in the final casting and is not lost during the casting process, so it is a measure of efficiency.
[0045] Samples of each casting were taken from both the thin-walled and thick-walled sections and prepared for metallographic examination. Figure 1 shows the results of the thin-walled section, and Figure 2 shows the results of the thick-walled section. Further data on the examination results is shown in Table 2 below.
[0046] [Table 2]
[0047] As shown in Figures 1 and 2, and in Table 2 above, the test results indicate that E1 and E3 can be used at half the concentration compared to the standard product. E2 and E4 can be used at one-quarter the concentration compared to the standard product.
[0048] The inventors also surprisingly found that inoculant composition E5 (compared to commercially available inoculant products containing 4% Zr, 3% Mn, 1.2% Ca, 1% Al, with the remainder being ferrosilicon (62-69% Si)) improved the performance of castings at slow cooling rates with wall thicknesses exceeding 50 mm (e.g., reduced casting defects).
[0049] All of the tested compositions E1 to E5 were equivalent to the comparative compositions, even though their addition rates were much lower than those of the example compositions E1 to E5.
Claims
1. An inoculant composition for processing molten iron, 10-90% by weight of the activator, Including 90-10% by weight of carrier, The aforementioned activator contains one or more of the following as its main components: barium, bismuth, manganese, and zirconium. The aforementioned inoculant composition is an inoculant composition containing less than 0.5% by weight of magnesium.
2. The inoculant composition according to any one of the preceding claims, wherein the activator comprises 3 to 40% by weight of zirconium.
3. The inoculant composition according to claim 2, wherein the activator comprises 3 to 25% by weight of bismuth.
4. The inoculant composition according to claim 2 or 3, wherein the activator contains 0.3 to 22% by weight of manganese.
5. The inoculant composition according to claim 1, wherein the activator contains 20 to 40% by weight of barium.
6. The inoculant composition according to any one of the preceding claims, wherein the activator comprises 0 to 10% by weight of calcium.
7. The inoculant composition contains less than 0.5% by weight of carbon, less than 0.1% by weight of sulfur, and / or less than 0.5% by weight of phosphorus.
8. The inoculant composition according to any one of the preceding claims, wherein the carrier comprises ferrosilicon.
9. The inoculant composition according to any one of the preceding claims, wherein the inoculant composition is formed in the form of a powder, granules, and / or tablets, and optionally, the inoculant composition is provided in pre-divided packages.
10. The inoculant composition according to claim 9, wherein the inoculant composition has a particle size or grain size of 0.2 mm to 12 mm.
11. A method of inoculating with molten iron, Supplying the inoculant composition described in any one of the preceding claims into a container, A method comprising adding molten iron to the aforementioned container.
12. A method for inoculating molten iron, comprising spraying an inoculant composition according to any one of claims 1 to 10 into a flow of molten iron.
13. The method according to claim 11 or claim 12, comprising adding less than 0.5% by weight of the inoculant composition relative to the weight of molten iron.
14. A method for producing an inoculant composition according to any one of claims 1 to 10, This involves reacting silica, iron, and carbon in a submerged arc furnace to form ferrosilicon and carbon dioxide, or remelting a ferrosilicon alloy in an induction furnace. Adding one or more activators to the furnace to produce an inoculant composition containing the activators and ferrosilicon alloyed with them, The inoculant composition is cooled and solidified, A method comprising grinding the aforementioned inoculant composition to produce a granular and / or powdered inoculant composition.
15. The method according to claim 14, further comprising mixing the granular and / or powdered inoculant composition with a further granular and / or powdered activator.