Oxygen-sulfur composite inoculant, preparation method and application

Abstract

The invention belongs to the technical field of casting, and provides an oxygen-sulfur composite inoculant and a preparation method thereof, the oxygen-sulfur composite inoculant is prepared from ferrosilicon, ferromanganese, silicon calcium, silicon barium, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; comprising 70 to 75 wt% of silicon, 1 to 1.5 wt% of calcium, 1 to 1.5 wt% of barium, 3 to 5 wt% of manganese, 0.6 to 1 wt% of sulfur, 1 to 1.5 wt% of oxygen and the balance of iron. When the oxygen-sulfur composite nucleating agent is applied, the problem that the internal graphitization effect cannot meet the basic requirement after an ultra-large casting is formed can be solved, the spheroidization level of the casting can reach the third level, the graphite size level basically reaches the sixth level, and then the requirement for the basic performance of the casting is met.

Description

Technical Field

[0001] This invention belongs to the field of casting technology, and particularly relates to oxygen-sulfur composite inoculants, their preparation methods, and applications. Background Technology

[0002] Inoculants, added to molten iron during metal casting, can promote graphitization, refine graphite, and improve mechanical properties. Based on traditional inoculants, oxygen and sulfur are added in combination. Utilizing the micro-reactions of oxygen and sulfur in molten iron, a stronger "heterogeneous nucleation" core is created. This forms dispersed, tiny heterogeneous crystal particles, which serve as effective heterogeneous nuclei for graphite crystallization, thereby enhancing the graphitization effect.

[0003] In actual production, it has been found that when oxygen-sulfur composite inoculants are applied to castings with complex shapes, it is difficult to achieve the ideal graphitization effect. In particular, when the wall thickness of the casting is uneven and the sulfur and oxygen content of the molten iron is low, there are relatively few nucleation sites during spheroidization inoculation treatment, which has an adverse effect on the graphitization effect of the casting. Summary of the Invention

[0004] This application addresses the technical problem of poor graphitization effect caused by insufficient nucleation sites during spheroidizing inoculation treatment in castings with complex shapes, where the casting wall thickness varies significantly and the sulfur and oxygen content of the molten iron is low. It proposes an oxygen-sulfur composite inoculator, its preparation method, and its application.

[0005] The specific technical solution is as follows: This application provides an oxygen-sulfur composite inoculant, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70-75 wt% silicon, 1-1.5 wt% calcium, 1-1.5 wt% barium, 3-5 wt% manganese, 0.6-1 wt% sulfur, 1-1.5 wt% oxygen, and the balance is iron.

[0006] Preferably, the molar ratio of manganese dioxide, iron oxide and ferrous oxide is (1~4):(1~2):(1~2).

[0007] Preferably, the molar ratio of manganese dioxide, iron oxide and ferrous oxide is 3:(1~1.5):(1~2).

[0008] Preferably, the molar ratio of iron oxide to ferrous oxide is 1:1.3.

[0009] Preferably, the ferrous sulfide has a particle size of 0.2~0.8 mm, of which 0.2~0.35 mm accounts for 15~25%, 0.35~0.6 mm accounts for 30~60%, and the remainder is 0.6~0.8 mm.

[0010] Preferably, in the ferrous sulfide, 20% are 0.2~0.35mm, 50% are 0.35~0.6mm, and the remainder are 0.6~0.8mm.

[0011] This application also provides a method for preparing an oxygen-sulfur composite inoculant, the method being: Ferrosilicon, ferromanganese, calcium silicon, and barium silicon are mixed, smelted, and cast into ingots, which are then crushed and sieved into ferrosilicon particles. Ferrosilicon particles are mixed with ferrous sulfide, manganese dioxide, ferric oxide, and ferrous oxide particles to obtain the oxygen-sulfur composite inoculant described in any of the above-mentioned items.

[0012] This application also provides an application of an oxygen-sulfur composite inoculant, wherein the oxygen-sulfur composite inoculant described in any of the above claims is used to cast castings by in-flow inoculation, thereby optimizing the spheroidization level and graphite size grade.

[0013] The beneficial effects of this invention are as follows: When applied, the oxygen-sulfur composite inoculant of the present invention can avoid the problem that the internal graphitization effect of castings with complex shapes and uneven wall thicknesses cannot meet the basic requirements after molding. It can enable the spheroidization level of the casting to reach level 3 and the graphite size level to basically reach level 6, thereby meeting the requirements for the basic performance of the casting. Attached Figure Description

[0014] Figure 1 The morphological image of the ductile iron casting prepared in Example 1 is shown. Figure 2 The morphology of the ductile iron casting prepared in Example 2 is shown in the figure. Figure 3 The graphite metallographic image of #23; Figure 4 The graphite metallographic image is for #24. Detailed Implementation

[0015] In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments. However, those skilled in the art will understand that the invention can be practiced without these details. In other instances, well-known structures have not been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments. Unless the context otherwise requires, throughout the specification and appended claims, the word "comprising" should be interpreted in an open-ended, inclusive sense, i.e., as "including but not limited to".

[0016] In this application, "wt%" refers to the percentage content by weight.

[0017] In this application, the numerical range of a single interval simultaneously includes two endpoint values, such as 0.2~0.35, which includes both 0.35 and 0.2; A continuous range of multiple intervals, where the smallest interval contains both endpoints, and other intervals contain the values ​​to the right. For example, in the interval 0.2 to 0.35, 0.2 to 0.25 includes 0.2 and 0.25, 0.25 to 0.3 includes 0.3, and 0.3 to 0.35 includes 0.35.

[0018] In this application, the method for determining the content of each component in the oxygen-sulfur compound probiotic is as follows: After the oxygen-sulfur composite inoculant is melted, the oxygen content is determined using a furnace-front oxygen probe, and the content of other elements is determined using a GS-LIBS2200 laser component analyzer.

[0019] In this application, all oxygen-sulfur composite inoculants involved in the embodiments, comparative examples, and preparation examples were prepared by the following method: (1) Mix ferrosilicon, ferromanganese, calcium silicon and barium silicon in proportion to obtain a mixed raw material; (2) Melt the mixed raw materials at 1300~1380 ℃ for 30~40 min, and then cast the alloy ingots using a metal mold. (3) The alloy ingot is crushed and sieved to obtain ferrosilicon particles; (4) Mix ferrosilicon particles with ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide particles to obtain an oxygen-sulfur composite inoculant. Example 1

[0020] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.05 wt% silicon, 1.05 wt% calcium, 1.48 wt% barium, 3.05 wt% manganese, 0.79 wt% sulfur, 1.32 wt% oxygen, with the balance being iron and unavoidable impurities.

[0021] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, ferric oxide, and ferrous oxide, with a molar ratio of 1:1:1.

[0022] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 2

[0023] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.13 wt% silicon, 1.07 wt% calcium, 1.42 wt% barium, 3.09 wt% manganese, 0.82 wt% sulfur, 1.27 wt% oxygen, with the balance being iron and unavoidable impurities.

[0024] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, ferric oxide, and ferrous oxide, with a molar ratio of 1:2:1.

[0025] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 3

[0026] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.22 wt% silicon, 1.02 wt% calcium, 1.47 wt% barium, 3.02 wt% manganese, 0.76 wt% sulfur, 1.34 wt% oxygen, with the balance being iron and unavoidable impurities.

[0027] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, iron oxide, and ferrous oxide, with a molar ratio of 1:1:2.

[0028] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 4

[0029] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.34 wt% silicon, 1.09 wt% calcium, 1.44 wt% barium, 3.07 wt% manganese, 0.84 wt% sulfur, 1.29 wt% oxygen, with the balance being iron and unavoidable impurities.

[0030] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, iron oxide, and ferrous oxide, with a molar ratio of 2:1:1.

[0031] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 5

[0032] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.47 wt% silicon, 1.04 wt% calcium, 1.49 wt% barium, 3.00 wt% manganese, 0.77 wt% sulfur, 1.25 wt% oxygen, with the balance being iron and unavoidable impurities.

[0033] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, ferric oxide, and ferrous oxide, with a molar ratio of 3:1:1.

[0034] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 6

[0035] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.58 wt% silicon, 1.00 wt% calcium, 1.41 wt% barium, 3.04 wt% manganese, 0.80 wt% sulfur, 1.31 wt% oxygen, with the balance being iron and unavoidable impurities.

[0036] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, ferric oxide, and ferrous oxide, with a molar ratio of 4:1:1.

[0037] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 7

[0038] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.92 wt% silicon, 1.06 wt% calcium, 1.45 wt% barium, 3.08 wt% manganese, 0.75 wt% sulfur, 1.28 wt% oxygen, with the balance being iron and unavoidable impurities.

[0039] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, ferric oxide, and ferrous oxide, with a molar ratio of 3:1:2.

[0040] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 8

[0041] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.14 wt% silicon, 1.08 wt% calcium, 1.40 wt% barium, 3.01 wt% manganese, 0.83 wt% sulfur, 1.33 wt% oxygen, with the balance being iron and unavoidable impurities.

[0042] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, ferric oxide, and ferrous oxide, with a molar ratio of 3:2:1.

[0043] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 9

[0044] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.43 wt% silicon, 1.01 wt% calcium, 1.46 wt% barium, 3.06 wt% manganese, 0.78 wt% sulfur, 1.30 wt% oxygen, with the balance being iron and unavoidable impurities.

[0045] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, ferric oxide and ferrous oxide. The molar ratio of manganese dioxide, ferric oxide and ferrous oxide is 3:1:1.5.

[0046] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 10

[0047] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.27 wt% silicon, 1.10 wt% calcium, 1.43 wt% barium, 3.10 wt% manganese, 0.81 wt% sulfur, 1.26 wt% oxygen, with the balance being iron and unavoidable impurities.

[0048] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, ferric oxide, and ferrous oxide. The molar ratio of manganese dioxide, ferric oxide, and ferrous oxide is 3:1.5:1.

[0049] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 11

[0050] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.69 wt% silicon, 1.03 wt% calcium, 1.50 wt% barium, 3.03 wt% manganese, 0.85 wt% sulfur, 1.35 wt% oxygen, with the balance being iron and unavoidable impurities.

[0051] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, ferric oxide and ferrous oxide. The molar ratio of manganese dioxide, ferric oxide and ferrous oxide is 3:1:1.1.

[0052] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 12

[0053] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.76 wt% silicon, 1.05 wt% calcium, 1.42 wt% barium, 3.05 wt% manganese, 0.79 wt% sulfur, 1.32 wt% oxygen, with the balance being iron and unavoidable impurities.

[0054] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, iron oxide and ferrous oxide. The molar ratio of manganese dioxide, iron oxide and ferrous oxide is 3:1:1.2.

[0055] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 13

[0056] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.81 wt% silicon, 1.00 wt% calcium, 1.47 wt% barium, 3.09 wt% manganese, 0.82 wt% sulfur, 1.27 wt% oxygen, with the balance being iron and unavoidable impurities.

[0057] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, ferric oxide and ferrous oxide. The molar ratio of manganese dioxide, ferric oxide and ferrous oxide is 3:1:1.3.

[0058] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm. Example 14

[0059] An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70.11 wt% silicon, 1.04 wt% calcium, 1.44 wt% barium, 3.02 wt% manganese, 0.76 wt% sulfur, 1.34 wt% oxygen, with the balance being iron and unavoidable impurities.

[0060] The sulfur comes from ferrous sulfide, and the oxygen comes from manganese dioxide, ferric oxide and ferrous oxide. The molar ratio of manganese dioxide, ferric oxide and ferrous oxide is 3:1:1.4.

[0061] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm.

[0062] Comparative Example 1 An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, ferric oxide and ferrous oxide; It includes: 70.54 wt% silicon, 1.03 wt% calcium, 1.47 wt% barium, 3.05 wt% manganese, 0.78 wt% sulfur, 1.33 wt% oxygen, with the balance being iron and unavoidable impurities.

[0063] Sulfur comes from ferrous sulfide, and oxygen comes from ferric oxide and ferrous oxide, with a molar ratio of 1:1 between ferric oxide and ferrous oxide.

[0064] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm.

[0065] Comparative Example 2 An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide and iron oxide; It includes: 70.23 wt% silicon, 1.04 wt% calcium, 1.45 wt% barium, 3.07 wt% manganese, 0.81 wt% sulfur, 1.29 wt% oxygen, with the balance being iron and unavoidable impurities.

[0066] Sulfur comes from ferrous sulfide, and oxygen comes from ferric oxide.

[0067] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm.

[0068] Comparative Example 3 An oxygen-sulfur composite inoculant is provided, which is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide and ferrous oxide; It includes: 70.57 wt% silicon, 1.07 wt% calcium, 1.44 wt% barium, 3.02 wt% manganese, 0.84 wt% sulfur, 1.34 wt% oxygen, with the balance being iron and unavoidable impurities.

[0069] Sulfur comes from ferrous sulfide, and oxygen comes from ferrous oxide.

[0070] The particle size of this oxygen-sulfur composite inoculant is between 0.2 and 0.8 mm.

[0071] Preparation Example 1 Based on the oxygen-sulfur composite inoculants of Examples 1-14 and Comparative Examples 1-3, the following method was used to prepare... Figure 1 The ductile iron casting shown: Weigh out 100 kg of pig iron, A3 steel, and recycled material in a ratio of 3:2:1, and mix and melt them together. Let it stand at 1520℃ for 5~10 minutes; The composition and content of the molten iron were as follows: carbon 3.7%, silicon 2.8%, manganese 0.15%, phosphorus 0.02%, sulfur 0.007%, and cerium 0.02%. The molten iron was spheroidized using a ladle spheroidizing method, with Mg5RE1 spheroidizing agent added at a rate of 1.4% of the molten iron weight. The oxygen-sulfur composite inoculant is added using the in-flow inoculation method, with an addition amount of 0.5% of the weight of the molten iron; the casting temperature is controlled between 1350 and 1370℃.

[0072] Result detection: According to GB / T 9441-2021 "Metallographic Examination of Ductile Cast Iron", the spheroidization level and graphite spheroidization grade of different ductile cast iron samples prepared in Example 1 were evaluated.

[0073] Among them, sample numbers 1#~14# correspond to Examples 1 to 14 respectively, and 15#~17# correspond to Comparative Examples 1 to 3 respectively.

[0074] The results are shown in Table 1.

[0075] Table 1 Based on the data in Table 1, and comparing the results of #1, #15, #16 and #17, it was found that when manganese dioxide is used as one of the sources of oxygen, the oxygen-sulfur composite inoculant can significantly provide a high spheroidization effect, improving the spheroidization level from level 4 to level 3, and the average diameter of the graphite spheres also becomes smaller.

[0076] Comparing the results of 1# to 6#, it was found that as the proportion of manganese dioxide in the oxygen source increases, the number of graphite spheres per unit area can be significantly increased, the average diameter of graphite spheres can be reduced, and the graphitization effect can be improved and optimized. The optimal molar ratio of manganese dioxide, iron oxide and ferrous oxide is 3:(1~1.5):(1~2).

[0077] Comparing the results of #1 and #11 to #14, it was found that within the preferred range of a molar ratio of manganese dioxide, iron oxide, and ferrous oxide of 3:(1~1.5):(1~2), appropriately increasing the content of ferrous oxide can significantly increase the number of graphite spheres per unit area and further reduce the average diameter of the graphite spheres, thereby improving and optimizing the graphitization effect. The preferred molar ratio of manganese dioxide, iron oxide, and ferrous oxide is 3:1:1.3. Example 15

[0078] Regarding the oxygen-sulfur composite inoculant in Example 13, the ferrous sulfide was further crushed to obtain ferrous sulfide particles with a particle size range of 0.2~0.8 mm, wherein the proportions of different particle size ranges are as follows: 0.2~0.35mm accounts for 15%, 0.35~0.6mm accounts for 30%, and 0.6~0.8mm accounts for 55%. Example 16

[0079] Regarding the oxygen-sulfur composite inoculant in Example 13, the ferrous sulfide was further crushed to obtain ferrous sulfide particles with a particle size range of 0.2~0.8 mm, wherein the proportions of different particle size ranges are as follows: 0.2~0.35mm accounts for 25%, 0.35~0.6mm accounts for 30%, and 0.6~0.8mm accounts for 45%. Example 17

[0080] Regarding the oxygen-sulfur composite inoculant in Example 13, the ferrous sulfide was further crushed to obtain ferrous sulfide particles with a particle size range of 0.2~0.8 mm, wherein the proportions of different particle size ranges are as follows: 0.2~0.35mm accounts for 15%, 0.35~0.6mm accounts for 60%, and 0.6~0.8mm accounts for 25%. Example 18

[0081] Regarding the oxygen-sulfur composite inoculant in Example 13, the ferrous sulfide was further crushed to obtain ferrous sulfide particles with a particle size range of 0.2~0.8 mm, wherein the proportions of different particle size ranges are as follows: 0.2~0.35mm accounts for 25%, 0.35~0.6mm accounts for 60%, and 0.6~0.8mm accounts for 15%. Example 19

[0082] Regarding the oxygen-sulfur composite inoculant in Example 13, the ferrous sulfide was further crushed to obtain ferrous sulfide particles with a particle size range of 0.2~0.8 mm, wherein the proportions of different particle size ranges are as follows: 0.2~0.35mm accounts for 20%, 0.35~0.6mm accounts for 30%, and 0.6~0.8mm accounts for 50%. Example 20

[0083] Regarding the oxygen-sulfur composite inoculant in Example 13, the ferrous sulfide was further crushed to obtain ferrous sulfide particles with a particle size range of 0.2~0.8 mm, wherein the proportions of different particle size ranges are as follows: 0.2~0.35mm accounts for 20%, 0.35~0.6mm accounts for 60%, and 0.6~0.8mm accounts for 20%. Example 21

[0084] Regarding the oxygen-sulfur composite inoculant in Example 13, the ferrous sulfide was further crushed to obtain ferrous sulfide particles with a particle size range of 0.2~0.8 mm, wherein the proportions of different particle size ranges are as follows: 0.2~0.35mm accounts for 20%, 0.35~0.6mm accounts for 50%, and 0.6~0.8mm accounts for 30%.

[0085] Preparation Example 2 Based on the oxygen-sulfur composite inoculant of Examples 15-21, the following method was used to prepare... Figure 2 The ductile iron casting shown: Weigh out 100 kg of pig iron, A3 steel, and recycled material in a ratio of 3:2:1, and mix and melt them together. Let it stand at 1520℃ for 5~10 minutes; This preparation example is from the same furnace of molten iron as Preparation Example 1. The difference lies in the use of a different oxygen-sulfur composite inoculant. Therefore, the composition and content of the molten iron will not be described again.

[0086] The molten iron was spheroidized using a ladle spheroidizing method, with Mg5RE1 spheroidizing agent added at a rate of 1.4% of the molten iron weight. The oxygen-sulfur composite inoculant is added using the in-flow inoculation method, with an addition amount of 0.5% of the weight of the molten iron; the casting temperature is controlled between 1350 and 1370℃.

[0087] Result detection: According to GB / T 9441-2021 "Metallographic Examination of Ductile Cast Iron", the spheroidization level and graphite spheroidization grade of different ductile cast iron samples prepared in Example 1 were evaluated.

[0088] Among them, sample numbers 18# to 24# correspond to Examples 15 to 21, respectively.

[0089] The results are shown in Table 2.

[0090] Table 2 Based on the data in Table 2, it was found that grading ferrous sulfide into different size ranges can significantly increase the number of graphite spheres per unit area and further reduce the average diameter of the graphite spheres, thereby improving and optimizing the graphitization effect. The optimal size range is 0.2~0.35mm, accounting for 15~25%, 0.35~0.6mm, accounting for 30~60%, and the remainder being 0.6~0.8mm. The even optimal size range is 0.2~0.35mm, accounting for 20%, 0.35~0.6mm, accounting for 50%, and the remainder being 0.6~0.8mm.

[0091] In this invention, the manganese content of the oxygen-sulfur composite inoculant is between 3% and 5%, and the actual graphitization effect obtained is extremely close. Moreover, within the range of 3% to 5%, it shows a typical trend of first increasing and then decreasing. Therefore, in the embodiments and comparative examples of this application, a content of about 3% is used for illustrative purposes.

[0092] in addition Figure 3 and Figure 4 Graphite metallographic images of #23 and #24, which showed better results, were also provided. Figure 3 Corresponding to graphite metallographic diagram #23, Figure 4 The graphite metallographic diagram corresponding to #24.

[0093] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. An oxygen-sulfur composite inoculant, characterized in that, It is made of ferrosilicon, ferromanganese, calcium silicon and barium silicon, ferrous sulfide, manganese dioxide, iron oxide and ferrous oxide; It includes: 70-75 wt% silicon, 1-1.5 wt% calcium, 1-1.5 wt% barium, 3-5 wt% manganese, 0.6-1 wt% sulfur, 1-1.5 wt% oxygen, and the balance is iron.

2. The oxygen-sulfur composite inoculant according to claim 1, characterized in that, The molar ratio of manganese dioxide, iron oxide and ferrous oxide is (1~4):(1~2):(1~2).

3. The oxygen-sulfur composite inoculant according to claim 2, characterized in that, The molar ratio of manganese dioxide, iron oxide and ferrous oxide is 3:(1~1.5):(1~2).

4. The oxygen-sulfur composite inoculant according to claim 3, characterized in that, The molar ratio of iron oxide to ferrous oxide is 1:1.

3.

5. The oxygen-sulfur composite inoculant according to claim 1, characterized in that, The ferrous sulfide has a particle size of 0.2~0.8 mm, of which 0.2~0.35 mm accounts for 15~25%, 0.35~0.6 mm accounts for 30~60%, and the remainder is 0.6~0.8 mm.

6. The oxygen-sulfur composite inoculant according to claim 5, characterized in that, The ferrous sulfide comprises 20% 0.2~0.35mm, 50% 0.35~0.6mm, and the remainder 0.6~0.8mm.

7. A method for preparing an oxygen-sulfur composite inoculant, characterized in that, The method is as follows: Ferrosilicon, ferromanganese, calcium silicon, and barium silicon are mixed, smelted, and cast into ingots, which are then crushed and sieved into ferrosilicon particles. Ferrosilicon particles are mixed with ferrous sulfide, manganese dioxide, ferric oxide and ferrous oxide particles to obtain the oxygen-sulfur composite inoculant according to any one of claims 1 to 6.

8. The application of oxygen-sulfur composite inoculant, characterized in that, The oxygen-sulfur composite inoculant according to any one of claims 1 to 6 is used to cast castings by in-flow inoculation, thereby optimizing the spheroidization level and graphite size grade.

Images