Silicon-carbon synergistically regulated method for preparing gray cast iron

Abstract

This invention relates to the field of ferrous metal casting technology, and more particularly to an optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation. The method calculates the wall thickness sensitivity coefficient of the casting based on the target size of the casting to determine the actual silicon-carbon ratio. Synthetic cast iron raw materials are added to an electric furnace for melting, and the composition is adjusted to the actual silicon-carbon ratio to obtain molten iron. The temperature of the molten iron is raised to 1500℃~1550℃ and allowed to stand for 3~5 minutes. The inoculation parameter adjustment data is determined based on the maximum temperature deviation during the standing process and the actual silicon-carbon ratio. The molten iron is poured into a preheated molten iron treatment ladle, and a silicon carbide inoculant is added before the molten iron is tapped from the furnace. A first addition of a barium silicon inoculant is made after the molten iron is tapped into the molten iron treatment ladle. The molten iron is then poured into a casting ladle for casting. A second addition of the barium silicon inoculant is made as the molten iron is poured into the sand mold, resulting in gray cast iron. This invention improves the mechanical properties and hardness uniformity of gray cast iron.

Description

Technical Field

[0001] This invention relates to the field of ferrous metal casting technology, and in particular to an optimized method for the preparation of gray cast iron based on the synergistic regulation of silicon and carbon. Background Technology

[0002] Gray cast iron, a key material for machine tool castings, is traditionally manufactured using a low silicon-to-carbon ratio (Si / C < 0.6) composition scheme. Under this approach, the carbon content is relatively high while the silicon content is significantly low, leading to systemic defects in the material's overall performance: First, the low silicon-to-carbon ratio induces the abnormal growth of coarse graphite flakes (such as D-type or E-type graphite), exacerbating stress concentration and weakening tensile strength; simultaneously, the tendency for hypereutectic formation easily causes graphite floating, reducing the density of the casting. Second, the lack of silicon weakens the graphitization ability; thin-walled areas are prone to forming hard and brittle cementite (white cast iron structure), while thick-walled areas, due to slow cooling, are prone to forming coarse pearlite or even ledeburite, resulting in an uneven matrix structure. Third, mechanical properties are significantly degraded, manifested as decreased tensile strength and increased fluctuations in the elastic modulus, directly affecting the rigidity and dimensional stability of the casting. Fourth, casting processability deteriorates. High carbon equivalent leads to a wider solidification range, increasing the risk of shrinkage porosity / cavity, and the excessive fluidity of the melt easily erodes the mold cavity, forming inclusions. Fifth, during machining, uneven hardness and weakened self-lubricating effect of coarse graphite exacerbate tool wear and worsen surface roughness. Sixth, the imbalance between eutecticness (Sc) and maturity (RG) prevents the full realization of material potential. Although increasing the silicon-carbon ratio (Si / C > 1.0) can improve these problems, excessive ferrite leads to insufficient strength and graphite distortion, which in turn causes uneven hardness in castings at different thicknesses. Existing technologies have consistently struggled to reconcile the balance between composition, microstructure, and properties.

[0003] Existing low silicon-carbon ratio processes cannot effectively coordinate and regulate the effects of silicon and carbon elements, resulting in systemic defects in gray cast iron in terms of graphite morphology, matrix uniformity, mechanical properties, and process adaptability. There is an urgent need to develop a method that can accurately match the structural characteristics of castings, dynamically optimize the silicon-carbon ratio, and coordinate and regulate the inoculation process to solve the problem of comprehensive performance degradation caused by composition-process mismatch.

[0004] Chinese Patent Publication No. CN111850381A discloses a method for producing gray cast iron, comprising the following steps: weighing 40%–50% scrap steel, 20%–25% iron filings, 35%–45% recycled material, and 1.6%–2.0% carbon raiser according to their mass percentages; sequentially adding the iron filings, scrap steel, carbon raiser, and recycled material into an electric furnace for melting, and adjusting the composition to obtain molten iron; providing an iron treatment ladle and a casting ladle, and preheating both the iron treatment ladle and the casting ladle to a certain temperature. The temperature is above 600℃; molten iron is poured into a preheated molten iron treatment ladle; passivation wire is provided to passivate the molten iron in the ladle; the passivation wire, by mass percentage, contains 45%–48% Si, 2.0%–2.5% Ca, 0.7%–0.9% Mg, 5.8%–6.2% Ba, and 20%–22% Re; the amount of passivation wire added is 13m per ton of molten iron; 75Si-Fe is weighed according to the mass ratio with the molten iron. 0.40%–0.60% and Sn 0.06%–0.08% are mixed evenly to obtain a mixture; the above mixture is added to a casting ladle, and then molten iron that has undergone wire feeding and passivation treatment is poured into the casting ladle; casting is performed, and gray cast iron is obtained after molding; it can be seen that the production method of gray cast iron has the following problems: the strength, stiffness and processing performance of low silicon-carbon ratio gray cast iron are deteriorated due to the unevenness of the structure. Summary of the Invention

[0005] Therefore, this invention provides an optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation, in order to overcome the problem of deterioration in strength, stiffness and machinability caused by the non-uniform microstructure of gray cast iron with low silicon-carbon ratio in the prior art.

[0006] To achieve the above objectives, this invention provides an optimized method for the preparation of gray cast iron based on the synergistic regulation of silicon and carbon, comprising:

[0007] Step S1: Calculate the wall thickness sensitivity coefficient of the casting based on the target size of the casting, and determine the actual silicon-carbon ratio of the casting based on the wall thickness sensitivity coefficient and the silicon-carbon ratio feedback factor.

[0008] Step S2: The synthetic cast iron raw materials are added to an electric furnace for melting and the composition is adjusted to the actual silicon-carbon ratio to obtain molten iron. The synthetic cast iron raw materials include scrap steel, scrap castings and silicon carbide.

[0009] Step S3: Raise the temperature of the molten iron to 1500℃~1550℃ and let it stand for 3~5 minutes. During the standing process, the maximum temperature deviation is detected. Based on the maximum temperature deviation and the actual silicon-carbon ratio, determine the inoculation parameter adjustment data, including the amount of silicon carbide adjustment and the amount of in-flow barium silicon inoculant addition rate adjustment.

[0010] Step S4: Pour the molten iron into a preheated molten iron treatment ladle, wherein...

[0011] Based on the aforementioned silicon carbide adjustment amount, a silicon carbide inoculant is added before the molten iron is tapped from the furnace.

[0012] After the molten iron is tapped from the furnace to the molten iron treatment ladle, a first dose of barium silicon inoculant is added, wherein the first dose of barium silicon inoculant is determined based on a reference first dose, the actual silicon-to-carbon ratio, and the maximum temperature deviation;

[0013] Step S5: The molten iron is poured into a casting ladle for casting and molding. In this step, based on the adjustment amount of the in-flow barium silicon inoculant addition rate, a second dose of barium silicon inoculant is added in-flow when the molten iron is poured into the sand mold. After molding, gray cast iron is obtained. The second dose is determined according to the adjustment amount of the in-flow barium silicon inoculant addition rate and the first dose.

[0014] Step S6: Correct the silicon-carbon ratio feedback factor based on the hardness difference of different wall thickness regions of the prepared gray cast iron.

[0015] Further, step S3 includes:

[0016] Step S31: Insert a thermocouple at the start of the settling process and continuously measure the settling temperature data of the molten iron.

[0017] Step S32: Obtain the maximum temperature deviation based on the static temperature data;

[0018] Step S33: Based on the maximum temperature deviation, determine whether to adjust the incubation parameters. If it is determined that the incubation parameters should be adjusted, then determine the adjustment amount of the basic silicon carbide and the adjustment amount of the basic in-flow barium silicon incubator addition rate based on the maximum temperature deviation.

[0019] Step S34: Correct the basic silicon carbide adjustment amount according to the actual silicon-carbon ratio to obtain the silicon carbide adjustment amount; correct the basic in-flow barium silicon inoculant addition rate adjustment amount according to the actual silicon-carbon ratio to obtain the in-flow barium silicon inoculant addition rate adjustment amount.

[0020] Further, step S1 includes:

[0021] Step S11: Determine the maximum and minimum wall thickness of the casting based on the target dimensions of the casting;

[0022] Step S12: Calculate the wall thickness sensitivity coefficient based on the maximum wall thickness and the minimum wall thickness;

[0023] Step S13: Determine the actual silicon-carbon ratio based on the wall thickness sensitivity coefficient and the silicon-carbon ratio feedback factor;

[0024] The minimum value of the actual silicon-carbon ratio is 0.7, and the maximum value is 0.9.

[0025] Further, in step S33, the maximum temperature deviation is compared with the maximum temperature deviation threshold to determine whether to adjust the gestation parameters. If the maximum temperature deviation is greater than or equal to the maximum temperature deviation threshold, it is determined that the gestation parameters should be adjusted. If the maximum temperature deviation is less than the maximum temperature deviation threshold, it is determined that the gestation parameters should not be adjusted.

[0026] Further, in step S4, the adjustment direction of the reference first dose is determined according to the actual silicon-carbon ratio, and the adjustment range of the reference first dose is determined according to the maximum temperature deviation, thereby obtaining the first dose.

[0027] Furthermore, in step S5, the second dose is negatively correlated with the first dose and positively correlated with the adjustment amount of the in-flow barium silicate inoculant addition rate.

[0028] Further, step S6 includes:

[0029] Step S61: Detect the hardness difference between the hardness of the maximum wall thickness region and the minimum wall thickness region of the gray cast iron sample.

[0030] Step S62: Compare the hardness difference with the target hardness difference to obtain the performance deviation characterization value;

[0031] Step S63: Based on the performance deviation characterization value, the silicon-carbon ratio feedback factor is corrected, wherein the silicon-carbon ratio feedback factor correction amount is determined based on the product of the performance deviation characterization value and a preset correction coefficient, and the silicon-carbon ratio feedback factor is updated according to the silicon-carbon ratio feedback factor correction amount.

[0032] Furthermore, the synthetic cast iron raw materials, by weight, include 60 to 80 parts of scrap steel, 20 to 40 parts of scrap castings, and 0.8 to 1.2 parts of silicon carbide.

[0033] Furthermore, the particle size of silicon carbide is 1 mm to 5 mm; the particle size of silicon carbide inoculant is 0.2 mm to 1 mm; the particle size of the first added barium silicon inoculant is 3 mm to 10 mm; and the particle size of the second added barium silicon inoculant is 0.2 mm to 0.8 mm.

[0034] Furthermore, in step S5, the pouring temperature is 1380℃~1420℃, and the pouring time is less than or equal to 10 minutes.

[0035] Compared with existing technologies, this invention significantly improves the comprehensive mechanical properties of gray cast iron by implementing precise process control under high silicon-to-carbon ratio conditions, and effectively improves the hardness uniformity of castings with different wall thicknesses. Based on the structural characteristics of the casting, the optimized silicon-to-carbon ratio is dynamically set, and combined with the temperature uniformity monitoring results of the molten iron settling process, the inoculation process parameters are adjusted in real time. This ensures that the advantages of graphite morphology refinement and matrix strengthening brought about by the high silicon-to-carbon ratio are fully utilized, and the microstructure and properties fluctuation caused by different cooling rates due to differences in wall thickness are effectively suppressed through targeted inoculation control. Thus, the overall strength and other key mechanical indicators of gray cast iron are improved, while the hardness difference between thick and thin areas of the casting is significantly reduced.

[0036] Furthermore, this invention employs a phased differential particle size inoculation process, using a coarse-grained barium silicon inoculant for bulk inoculation within the molten iron treatment ladle, while simultaneously using a fine-grained barium silicon inoculant for instantaneous inoculation during the casting stage. This enhances the overall nucleation capability and local resistance to supercooling, particularly ensuring the graphitization effect in thin-walled regions.

[0037] Furthermore, this invention introduces silicon carbide as a smelting additive into the synthetic cast iron raw materials, utilizing its high-temperature decomposition characteristics to simultaneously provide a carbon source and nucleation substrate. This reduces the dependence on ferrosilicon while improving the nucleation conditions of the molten iron, creating a favorable metallurgical environment for subsequent inoculation treatment.

[0038] Furthermore, this invention dynamically sets the actual silicon-carbon ratio based on the wall thickness sensitivity coefficient, so that the silicon-carbon composition ratio is accurately matched to the structural characteristics of the casting. It automatically reduces the silicon-carbon ratio in thick cross-sectional areas to suppress graphite coarsening, while maintaining a high silicon-carbon ratio in thin-walled areas to ensure complete graphitization. This reduces the microstructure inhomogeneity caused by wall thickness differences from the source of composition design.

[0039] Furthermore, this invention establishes a quantitative evaluation mechanism for melt uniformity by monitoring the maximum temperature deviation during the molten iron settling process and setting an adjustment threshold. When the temperature fluctuation exceeds the limit, the adjustment amount of the basic inoculation parameters is generated based on the deviation value, thereby realizing a real-time response to the metallurgical state of the molten iron and effectively compensating for the imbalance in nucleation core distribution caused by insufficient melt convection.

[0040] Furthermore, by employing a strategy linked to the first dose to determine the second dose, this invention achieves coordinated allocation of inoculation resources between overall inoculation and instantaneous in-flow inoculation. This ensures that, while guaranteeing the overall nucleation capacity of molten iron, the inoculation intensity during the casting stage is precisely controlled according to the pretreatment status. In particular, it strengthens the suppression effect on the tendency of undercooling in thin-walled areas, while avoiding an inappropriate increase in the total inoculation amount.

[0041] Furthermore, this invention establishes an adaptive closed-loop optimization mechanism for process parameters by correcting the silicon-carbon ratio based on the hardness difference of the casting body. According to the actual performance of the final product, the silicon-carbon ratio is corrected within a certain range, gradually approaching the optimal process window for a specific product, which significantly improves the adaptability and stability of the process. Attached Figure Description

[0042] Figure 1 The flowchart shows the optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation according to the present invention.

[0043] Figure 2 This is a flowchart of step S1 of the optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation of the present invention;

[0044] Figure 3 This is a flowchart of step S3 of the optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation of the present invention;

[0045] Figure 4 This is a flowchart of step S6 of the optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation according to the present invention. Detailed Implementation

[0046] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0047] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0048] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0049] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] Please see Figure 1 The diagram shows a flowchart of the optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation according to the present invention. An embodiment of the present invention provides an optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation, comprising:

[0051] Step S1: Calculate the wall thickness sensitivity coefficient of the casting based on the target size of the casting, and determine the actual silicon-carbon ratio of the casting based on the wall thickness sensitivity coefficient and the silicon-carbon ratio feedback factor.

[0052] Please see Figure 2 The diagram shows a flowchart of step S1 of the optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation according to the present invention. Specifically, step S1 includes:

[0053] Step S11: Determine the maximum and minimum wall thickness of the casting based on the target dimensions of the casting;

[0054] Step S12: Calculate the wall thickness sensitivity coefficient based on the maximum wall thickness and the minimum wall thickness;

[0055] In a specific embodiment, based on the three-dimensional model of the casting, the minimum wall thickness dmin and maximum wall thickness dmax of the casting are extracted using CAD software. The calculation formula for the wall thickness sensitivity coefficient is as follows:

[0056]

[0057] Where K is the wall thickness sensitivity coefficient, which is dimensionless, and its calculation result is retained to one decimal place; d min Minimum wall thickness, in millimeters (mm); d max This represents the maximum wall thickness, expressed in millimeters (mm).

[0058] It is understandable that the wall thickness sensitivity coefficient quantitatively characterizes the structural complexity of castings. The larger the K value, the more significant the difference in cooling rate between thick and thin areas, which is the core factor leading to uneven microstructure.

[0059] Step S13: Determine the actual silicon-carbon ratio based on the wall thickness sensitivity coefficient and the silicon-carbon ratio feedback factor;

[0060] The actual silicon-to-carbon ratio typically needs to be within the operating range, with a minimum value of 0.7 and a maximum value of 0.9.

[0061] In one specific embodiment, the actual silicon-to-carbon ratio (Si / C) is determined based on the K value according to the following rules:

[0062] When K ≤ 2.5: Si / C = 0.85 + u,

[0063] When 2.5 < K ≤ 4.0: Si / C = 0.80 + u,

[0064] When K > 4.0: Si / C = 0.75 + u;

[0065] Where u is the silicon-carbon ratio feedback factor, which is dimensionless and u∈[-0.05,0.05]. For the first production of a single batch of castings, u is taken as 0.

[0066] Understandably, the principle of setting the silicon-carbon ratio is based on the correlation mechanism between wall thickness sensitivity and solidification behavior. Castings with low K values ​​have a uniform structure, and a higher silicon-carbon ratio can fully refine the graphite. Castings with high K values ​​need to suppress graphite coarsening in thick-walled areas, so the silicon-carbon ratio is reduced. The optimal value of the silicon-carbon ratio is calibrated through several historical experiments, and fine-tuned within the range by using a silicon-carbon ratio feedback factor to ensure a balance between graphite morphology and matrix strength under the constraint of CE=3.9~4.1, ultimately reducing the hardness difference between different wall thickness areas.

[0067] Step S2: The synthetic cast iron raw materials are added to an electric furnace for melting and the composition is adjusted to the actual silicon-carbon ratio to obtain molten iron. The synthetic cast iron raw materials include scrap steel, scrap castings and silicon carbide.

[0068] Specifically, the synthetic cast iron raw materials, by weight, include 60 to 80 parts scrap steel, 20 to 40 parts scrap castings, and 0.8 to 1.2 parts silicon carbide.

[0069] Specifically, the particle size of silicon carbide is 1 mm to 5 mm.

[0070] In one specific embodiment, a power frequency induction furnace is used for the smelting operation, which specifically includes:

[0071] Weigh the raw materials for synthesizing cast iron according to the following weight proportions: 60 to 80 parts of scrap steel, preferably scrap steel chips or crushed material, 20 to 40 parts of scrap castings of the same material (the scrap castings need to be shot blasted), and 0.8 to 1.2 parts of silicon carbide with a particle size of 1 mm to 5 mm.

[0072] Layered feeding: scrap steel is laid at the bottom, scrap castings are added in the middle, and silicon carbide is covered at the top;

[0073] Electro-melting: control the power density to be 500-600 kW / ton, and the melting time to be ≤45 minutes;

[0074] Composition adjustment: After melting and cleaning, samples are taken for spectral analysis. The silicon-carbon ratio is precisely adjusted to the actual silicon-carbon ratio determined by S1 by adding carbon raiser or ferrosilicon.

[0075] Understandably, the partial replacement of ferrosilicon with silicon carbide in synthetic cast iron raw materials can reduce smelting costs and provide a nucleation substrate to improve the metallurgical quality of cast iron.

[0076] Step S3: Raise the temperature of the molten iron to 1500℃~1550℃ and let it stand for 3~5 minutes. During the standing process, the maximum temperature deviation is detected. Based on the maximum temperature deviation and the actual silicon-carbon ratio, determine the inoculation parameter adjustment data, including the amount of silicon carbide adjustment and the amount of in-flow barium silicon inoculant addition rate adjustment.

[0077] Please continue reading. Figure 3 The diagram shows a flowchart of step S3 in the optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation of the present invention. Specifically, step S3 includes:

[0078] Step S31: Insert a thermocouple at the start of the settling process and continuously measure the settling temperature data of the molten iron.

[0079] Step S32: Obtain the maximum temperature deviation based on the static temperature data;

[0080] In one specific embodiment, a power frequency induction furnace is used to perform high-temperature settling treatment. The molten iron with adjusted composition is heated to the target temperature range at a rate of 50-100°C / min. When the molten iron temperature reaches the range of 1500°C-1550°C, the furnace power is cut off to stop heating, the furnace lid timer is turned on, and a settling and heat preservation period of 3-5 minutes is started. An S-type platinum-rhodium thermocouple (with corundum protective sheath) is inserted to 1 / 3 of the depth of the molten iron. The settling process is continuously monitored by a temperature recorder, and the maximum temperature deviation is calculated and recorded as ΔT. ΔT is the absolute value of the difference between the highest temperature and the lowest temperature during settling, in degrees Celsius (°C).

[0081] Step S33: Based on the maximum temperature deviation, determine whether to adjust the incubation parameters. Based on the determination result of adjusting the incubation parameters, determine the basic silicon carbide adjustment amount and the basic in-flow barium silicon incubator addition rate adjustment amount according to the maximum temperature deviation.

[0082] Specifically, in step S33, the maximum temperature deviation is compared with the maximum temperature deviation threshold to determine whether to adjust the gestation parameters. If the maximum temperature deviation is greater than or equal to the maximum temperature deviation threshold, it is determined that the gestation parameters should be adjusted. If the maximum temperature deviation is less than the maximum temperature deviation threshold, it is determined that the gestation parameters should not be adjusted.

[0083] In one specific embodiment, the maximum temperature deviation threshold ΔT th =5℃, when the maximum temperature deviation ΔT is greater than ΔT th When calculating the basic adjustment amount, use the following formula:

[0084] The specific adjustment amount for basic silicon carbide is: ΔQ = k1 × (ΔT - ΔT) th );

[0085] Adjustment amount of basic in-flow barium silicate inoculant addition rate: ΔV = k2 × (ΔT - ΔT) th );

[0086] Wherein, ΔQ is in percentage (%), representing the proportion of molten iron by weight; ΔV is in percentage (%), representing the increase relative to the baseline addition rate.

[0087] When ΔT≤ΔT th At this time, no adjustments are made to the gestation parameters, i.e., ΔQ=0 and ΔV=0.

[0088] Where, ΔT th The value range is 5–6℃, preferably ΔT. th The temperature is set to 5℃; the value of k1 ranges from 0.005% to 0.015% / ℃, preferably 0.01% / ℃; the value of k2 ranges from 3% to 7% / ℃, preferably 5% / ℃. The setting of ΔTth is based on industrial practice showing that when the temperature fluctuation is less than this value, the uniformity of the molten iron meets the requirements; the values ​​of k1 and k2 are determined through production experiments, and their physical meanings are respectively the proportion of silicon carbide addition required to compensate for the unit temperature deviation increment and the proportion of adjustment of the inoculant rate.

[0089] Understandably, this step quantifies the homogeneity of molten iron through temperature fluctuations and dynamically adjusts the inoculation parameters accordingly. Uneven temperature distribution during the molten iron's settling process directly reflects insufficient convection and incomplete solute diffusion within the melt, leading to an imbalance in the nucleation core distribution. When temperature fluctuations exceed a safe threshold, it signifies the need for enhanced inoculation treatment to compensate for nucleation capacity. Increasing the amount of silicon carbide added before tapping replenishes the number of nucleation substrates, while increasing the in-flow inoculation agent addition rate strengthens the immediate nucleation effect in thin-walled regions. This feedback control mechanism based on real-time monitoring data effectively overcomes the insufficient adaptability of traditional fixed-parameter inoculation methods to changes in melt state, ensuring that different batches of molten iron receive stable inoculation treatment intensity, thereby eliminating differences in microstructure and properties caused by melt homogeneity fluctuations.

[0090] Step S34: Correct the basic silicon carbide adjustment amount according to the actual silicon-carbon ratio to obtain the silicon carbide adjustment amount; correct the basic in-flow barium silicon inoculant addition rate adjustment amount according to the actual silicon-carbon ratio to obtain the in-flow barium silicon inoculant addition rate adjustment amount.

[0091] In one specific embodiment, the basic silicon carbide adjustment amount ΔQ and the basic in-flow barium silicon inoculant addition rate adjustment amount ΔV are corrected according to the actual silicon-to-carbon ratio (Si / C):

[0092] Silicon carbide adjustment amount: ΔQ s =ΔQ1×α,

[0093] Where α = -2 × (Si / C) + 2.6;

[0094] Adjustment amount of in-flow barium silicate inoculant addition rate: ΔV s =ΔV×β,

[0095] Where β = -2 × (Si / C) + 2.6;

[0096] The correction coefficients α and β both range from 0.8 to 1.2. Preferably, α and β are set to 1.2 when the actual silicon-to-carbon ratio is 0.7, and to 0.8 when the actual silicon-to-carbon ratio is 0.9. The coefficient -2 and the constant 2.6 are set based on the fact that for every 0.1 increase in the silicon-to-carbon ratio, the correction coefficient decreases by 0.2 to compensate for the influence of the silicon-to-carbon ratio on the graphitization ability. This linear relationship was calibrated through several batches of production tests, which will not be elaborated here.

[0097] Understandably, when the maximum temperature deviation exceeds the threshold, it indicates insufficient convection within the melt, resulting in uneven distribution of nucleation substrates due to undecomposed silicon carbide particles or solute agglomeration. In this case, increasing the amount of silicon carbide can supplement effective nucleation nuclei, but the specific increment needs to be dynamically adjusted based on the actual silicon-to-carbon ratio: when the silicon-to-carbon ratio is high, the molten iron has a strong graphitization ability, and the increment needs to be appropriately reduced to avoid excessive nucleation leading to grain coarsening; when the silicon-to-carbon ratio is low, the molten iron's basic graphitization ability is insufficient, and the amount added needs to be significantly increased to compensate for nucleation defects. This dual feedback mechanism ensures that the number of nucleation nuclei always precisely matches the metallurgical state of the melt, guaranteeing the uniformity of the solidification structure from the source.

[0098] Understandably, the adjustment of the inoculant addition rate focuses on suppressing undercooling in thin-walled regions during the casting stage. Excessive temperature fluctuations indicate deterioration in melt homogeneity, necessitating an increased addition rate to enhance the instantaneous nucleation strength when molten iron is poured into the mold cavity. However, the rate adjustment needs to be coupled with the silicon-carbon ratio for secondary correction: under low silicon-carbon ratio conditions, the inherent graphitization ability of the molten iron is weak, and white iron is more likely to form in thin-walled regions, thus requiring a significant increase in the rate to ensure rapid formation of effective nuclei; under high silicon-carbon ratio conditions, the molten iron's resistance to undercooling is enhanced, allowing for a moderate reduction in the rate adjustment to prevent over-inoculation. This dynamic control strategy enables the inoculant to precisely release its nucleation potential in the thin-walled regions with the fastest cooling rate, completely eliminating microstructural abnormalities caused by localized undercooling.

[0099] Step S4: Pour the molten iron into a preheated molten iron treatment ladle, wherein...

[0100] Based on the aforementioned silicon carbide adjustment amount, a silicon carbide inoculant is added before the molten iron is tapped from the furnace.

[0101] After the molten iron is tapped from the furnace to the molten iron treatment ladle, a first dose of barium silicon inoculant is added, wherein the first dose of barium silicon inoculant is determined based on a reference first dose, the actual silicon-to-carbon ratio, and the maximum temperature deviation;

[0102] Specifically, in step S4, the adjustment direction of the reference first dose is determined according to the actual silicon-carbon ratio, and the adjustment range of the reference first dose is determined according to the maximum temperature deviation, thereby obtaining the first dose.

[0103] In one specific embodiment, a ductile iron molten iron treatment ladle (capacity 3-5 tons) preheated to 600-800℃ is used, and the following operations are performed: before the molten iron is tapped from the furnace, silicon carbide inoculant (particle size 0.2-1mm) is added according to the silicon carbide adjustment amount determined in S34; the molten iron in the electric furnace is poured into the molten iron treatment ladle, and the pouring time is controlled within 2-3 minutes; after all the molten iron has entered the treatment ladle, the first dose of barium silicon inoculant is added through an automatic feeder.

[0104] The first dose (D1) is calculated using the following formula:

[0105] D1=D 1b +△D 1;

[0106] Where D1 is the final first dose, in percentage (%) of molten iron weight; Db is the baseline first dose, in percentage (%) of molten iron weight; △D1 is the first dose adjustment, in percentage (%) of molten iron weight.

[0107] First dose of baseline D b The value range is 0.3% to 0.5%, preferably, D b Take 0.4%. This range is determined based on the conventional addition amount of barium silicon inoculant used in in vivo incubation in industry, which can provide an effective basis for overall nucleation.

[0108] In a specific embodiment, the formula for calculating the first dose adjustment amount ΔD1 is as follows:

[0109] ,

[0110] Wherein, k3 is the silicon-to-carbon ratio influence coefficient, in units of % / 0.1 (i.e., the percentage change in dose caused by every 0.1 units of silicon-to-carbon ratio); Si / C is the actual silicon-to-carbon ratio; F is the silicon-to-carbon ratio reference value, dimensionless; k4 is the temperature deviation influence coefficient, in units of % / ℃; ΔT is the maximum temperature deviation, in units of ℃; ΔTth is the maximum temperature deviation threshold, in units of ℃.

[0111] The reference value for the silicon-to-carbon ratio, F, is 0.80, which is the median of the ideal silicon-to-carbon ratio for optimal tissue homogeneity. The silicon-to-carbon ratio influence coefficient k3 ranges from -0.02 to -0.06% / 0.1, preferably -0.04% / 0.1. A negative value indicates that when the actual silicon-to-carbon ratio is higher than the reference value, the first dose needs to be reduced. The temperature deviation influence coefficient k4 ranges from 0.005% to 0.015% / ℃, preferably 0.01% / ℃. A positive value indicates that when the temperature deviation exceeds the threshold, the first dose needs to be increased to compensate for homogeneity. The values ​​of coefficients k3 and k4 were obtained through regression analysis of multiple sets of process experiments. Their physical meanings are the required compensating dose for a unit silicon-to-carbon ratio deviation and a unit temperature deviation, respectively, which will not be elaborated further here.

[0112] Understandably, unlike the silicon carbide inoculant added before tapping, which mainly provides a heterogeneous nucleation substrate and supplements the carbon source, the core function of the barium silicon inoculant lies in its strong graphitization promoting ability. By introducing active silicon and barium elements, it significantly reduces the tendency of the molten iron to undercool and refines and rounds the graphite morphology. The adjustment logic of the model considers the differentiated effects of the silicon-to-carbon ratio and temperature deviation on the solidification behavior of the molten iron: the actual silicon-to-carbon ratio directly reflects the inherent graphitization potential of the molten iron. When its value is high, it indicates that the molten iron itself already has a strong graphitization tendency. At this time, if too much barium silicon inoculant is added, it is not only uneconomical, but may also lead to coarse eutectic clusters or even excessive ferrite due to over-inoculation, thereby weakening the matrix strength. Therefore, the first dosage needs to be appropriately reduced according to the silicon-to-carbon ratio. Conversely, when the silicon-to-carbon ratio is low, the inherent graphitization ability of the molten iron is insufficient, and white iron structure is prone to appear in thin-walled areas. At this time, the first dosage needs to be significantly increased to forcibly promote graphitization and ensure the uniformity of the matrix structure. The maximum temperature deviation reveals defects in the macroscopic uniformity of the molten iron. A large deviation indicates a significant temperature gradient and compositional segregation within the melt, which directly leads to uneven distribution of nucleation cores and asynchronous solidification processes. To address this, increasing the initial dosage of barium silicon inoculant can leverage its powerful instantaneous nucleation ability to rapidly and abundantly generate new eutectic clusters throughout the entire molten iron ladle. This effectively smooths out the differences in nucleation capabilities across regions caused by initial inhomogeneity, laying the foundation for obtaining castings with high microstructure consistency.

[0113] Step S5: The molten iron is poured into a casting ladle for casting and molding. In this step, based on the adjustment amount of the in-flow barium silicon inoculant addition rate, a second dose of barium silicon inoculant is added in-flow when the molten iron is poured into the sand mold. After molding, gray cast iron is obtained. The second dose is determined according to the adjustment amount of the in-flow barium silicon inoculant addition rate and the first dose.

[0114] Specifically, the second dose is negatively correlated with the first dose and positively correlated with the adjustment amount of the in-flow barium silicate inoculant addition rate.

[0115] Specifically, the particle size of the silicon carbide inoculant is 0.2 mm to 1 mm; the particle size of the first added barium silicon inoculant is 3 mm to 10 mm; and the particle size of the second added barium silicon inoculant is 0.2 mm to 0.8 mm.

[0116] Specifically, in step S5, the pouring temperature is 1380℃~1420℃, and the pouring time is less than or equal to 10 minutes.

[0117] In one specific embodiment, a teapot-type casting ladle (capacity 500-800 kg) is used to perform the following operations: molten iron is transferred from the treatment ladle to the casting ladle, with a transfer time ≤ 3 minutes; the casting temperature is controlled within the range of 1380-1420℃; the molten iron is poured into the sand mold through the casting trough, with a casting time ≤ 10 minutes; during the casting process, a second dose of barium silicate inoculant is added through a feeder according to the adjusted amount of the in-flow barium silicate inoculant addition rate determined in S34, wherein the actual addition rate = basic addition rate × (adjustment amount of in-flow barium silicate inoculant addition rate + 100%); the basic addition rate is preferably 25% of the total amount of in-flow barium silicate inoculant added per minute.

[0118] The specific formula for calculating the second dose is as follows:

[0119] ,

[0120] Where D2 is the second dosage, expressed as a percentage (%) of molten iron by weight; k5 is the first dosage compensation coefficient, dimensionless; D max D1 is the upper limit of the first dosage, expressed as a percentage (%) of the molten iron weight; D6 is the first dosage, expressed as a percentage (%) of the molten iron weight; k6 is the conversion coefficient for flow adjustment, expressed as % / %, which physically converts a unit percentage rate adjustment into a second dosage addition ratio; ΔV s The adjustment amount for the in-flow barium silicate inoculant addition rate determined in step S34 is expressed as a percentage (%), representing the adjustment ratio relative to the baseline addition rate.

[0121] Among them, the conventional upper limit of the first dose DmaxA value of 0.5% is taken, corresponding to the upper limit of the conventional addition range of the first dose. The value of the first dose compensation coefficient k5 ranges from 1 to 3, preferably k5 is 2. Its physical meaning is the proportion of the second dose required to compensate for a unit difference when the first dose is lower than the upper limit. The value of the flow adjustment conversion coefficient k6 ranges from 0.001 to 0.002, preferably k6 is 0.001. Its physical meaning is to convert the unit proportion of rate adjustment into the proportion of the second dose addition. The values ​​of coefficients k5 and k6 are calibrated through multiple sets of process tests to ensure that the calculated result of the second dose falls within the conventionally effective addition range (usually 0.1% to 0.2% of the weight of molten iron).

[0122] Understandably, the first dose, acting as a bulk inoculation, establishes the overall nucleation basis for molten iron within the ladle, and its magnitude directly reflects the sufficiency of the initial inoculation. Therefore, the determination of the second dose must be linked to the first dose: if the first dose is high, it indicates that the overall nucleation core is sufficient, and to avoid excessive total inoculation leading to decreased economic efficiency or overly dense eutectic clusters, or even inoculation defects, the second dose of in-flow inoculation should be appropriately reduced; conversely, if the first dose is insufficient, it needs to be compensated by stronger in-flow inoculation, showing a negative correlation. Simultaneously, the adjustment of the in-flow barium silicon inoculator addition rate directly stems from the assessment of the molten iron's homogeneity and composition. An increased value indicates a significant tendency for undercooling or poor homogeneity in the melt, necessitating an increase in the second dose during casting to enhance instantaneous nucleation, especially in thin-walled regions with rapid cooling rates, to suppress white iron formation; therefore, the two are positively correlated.

[0123] Step S6: Correct the wall thickness sensitivity coefficient based on the hardness difference between different wall thickness regions of the prepared gray cast iron.

[0124] Please continue reading. Figure 4 The diagram shows a flowchart of step S6 in the optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation of the present invention. Specifically, step S6 includes:

[0125] Step S61: Detect the hardness difference between the hardness of the maximum wall thickness region and the minimum wall thickness region of the gray cast iron sample.

[0126] Step S62: Compare the hardness difference with the target hardness difference to obtain the performance deviation characterization value;

[0127] Step S63: Based on the performance deviation characterization value, the wall thickness sensitivity coefficient is corrected, wherein the wall thickness sensitivity coefficient correction amount is determined based on the product of the performance deviation characterization value and a preset correction coefficient, and the wall thickness sensitivity coefficient is updated according to the correction amount.

[0128] In one specific embodiment, at least three samples are randomly selected from castings produced in the same batch. A test surface is set in both the maximum and minimum wall thickness regions. The test surfaces are ground. Using a Brinell hardness tester, at least five points are evenly selected on the test surface of each sample for hardness testing. The average hardness of all test points in the maximum wall thickness region and the average hardness of all test points in the minimum wall thickness region are calculated and denoted as H0. max and H min The unit is HBW. The hardness difference (ΔH) is H. max -H min denoted as ΔH;

[0129] Understandably, the hardness difference ΔH is a quantitative indicator for evaluating the uniformity of microstructure in different wall thickness areas of a casting.

[0130] Step S62: Compare the hardness difference with the target hardness difference to obtain the performance deviation characterization value;

[0131] In one specific embodiment, a target value for the hardness difference is set according to the material grade and usage requirements of the casting, and the performance deviation characterization value is calculated using the following formula:

[0132] ,

[0133] Where d is the performance deviation characterization value, which is dimensionless; △H t The target value for hardness difference is expressed in HBW, and the target value for hardness difference is ΔH. t The value range is from 10HBW to 15HBW. Preferably, for high-strength gray cast iron (such as HT250 and above), ΔH t The target value is set at 10 HBW. This target value is determined based on the requirements for microstructure uniformity in industry standards such as machine tool castings, and in conjunction with actual production levels. The performance deviation characterization value d is a dimensionless parameter, and its positive or negative sign indicates the relative degree to which the actual hardness difference exceeds or fails to reach the target value.

[0134] Step S63: Based on the performance deviation characterization value, the silicon-carbon ratio feedback factor is corrected, wherein the silicon-carbon ratio feedback factor correction amount is determined based on the product of the performance deviation characterization value and a preset correction coefficient, and the silicon-carbon ratio feedback factor is updated according to the silicon-carbon ratio feedback factor correction amount.

[0135] In a specific embodiment, the formula for calculating the feedback factor correction is as follows:

[0136] Δu=m×d,

[0137] Where m is a preset correction coefficient, which is dimensionless. The updated silicon-to-carbon ratio feedback factor is the sum of the silicon-to-carbon ratio feedback factor correction amount and the silicon-to-carbon ratio feedback factor during the previous production run.

[0138] The preset correction coefficient m ranges from 0.02 to 0.05, preferably m is 0.02; this coefficient determines the strength of a single feedback correction, and its value is obtained through analysis of historical process data, which will not be elaborated here.

[0139] Understandably, when the measured hardness difference exceeds the target value, it indicates that the uniformity of the casting structure is not ideal, and the originally set silicon-carbon ratio has failed to effectively balance the cooling differences between thick and thin regions. In this case, by appropriately reducing the silicon-carbon ratio setting through feedback, it is more inclined to suppress graphite coarsening in the thick-walled region and promote uniform structure. Conversely, when the hardness difference is less than the target value, it indicates that the original setting may be too conservative, and the silicon-carbon ratio should be appropriately increased to further unleash the material's performance potential and improve machinability.

[0140] Example 1:

[0141] Based on the 3D model of the casting, the maximum wall thickness was determined to be 50 mm and the minimum wall thickness to be 15 mm. The calculated wall thickness sensitivity coefficient K was 3.33. According to the preset rules, the actual silicon-to-carbon ratio (Si / C) was determined to be 0.80.

[0142] The smelting was carried out using an industrial frequency induction furnace. The raw materials for the synthetic cast iron were proportioned as follows by weight: 700 kg of scrap steel, 280 kg of scrap castings of the same material, and 9 kg of silicon carbide with a particle size of 1-5 mm. After melting, samples were taken for spectral analysis. By adding carburizing agents and ferrosilicon, the composition of the molten iron was precisely adjusted to a carbon equivalent (CE) of 4.05% and a silicon-to-carbon ratio (Si / C) of 0.80.

[0143] The molten iron was heated to 1520℃ and allowed to stand for 4 minutes. During the standing period, the maximum temperature deviation ΔT was measured to be 7℃ (exceeding the 5℃ threshold). Based on the maximum temperature deviation, the basic silicon carbide adjustment amount ΔQ and the basic in-flow barium silicon inoculant addition rate adjustment amount ΔV were calculated. The basic adjustment amounts were then corrected based on the actual silicon-to-carbon ratio Si / C = 0.80. Finally, the silicon carbide adjustment amount ΔQs was determined to be 0.02% of the molten iron weight, and the in-flow barium silicon inoculant addition rate adjustment amount ΔVs was determined to be 10% higher than the baseline rate.

[0144] The molten iron is poured into a ladle preheated to 700℃. Before tapping, silicon carbide inoculant with a particle size of 0.2–1 mm is added according to the calculated ΔQs (the actual total amount added is approximately 0.1978 kg). During the tapping process, a first dose of barium silicon inoculant (particle size 3–10 mm) is added. Based on the baseline first dose (0.4%), the actual silicon-to-carbon ratio (0.80), and the maximum temperature deviation (7℃), the first dose is determined to be 0.42% of the molten iron weight (4.1538 kg).

[0145] The molten iron is transferred to a casting ladle, and the casting temperature is controlled at 1400℃ for 8 minutes. During the casting process, based on ΔVs (+10%) determined in step S3 and the first dosage (0.42%) added in step S4, the follow-up feeder is controlled to add a second dosage of barium silicon inoculant (particle size 0.2-0.8mm) at a rate of 27.5% per minute. The second dosage is 0.17% of the weight of the molten iron (1.6813kg).

[0146] Sampling and testing of the casting revealed a hardness of 207 HBW at the maximum wall thickness and 192 HBW at the minimum wall thickness, a difference of 15 HBW. Based on this hardness difference compared to the target value (10 HBW), a performance deviation characterization value of -0.5 was calculated, leading to a feedback factor correction of -0.01. The updated silicon-carbon ratio feedback factor of -0.01 will be used for the production of the next batch of castings with the same structure.

[0147] Example 2:

[0148] The difference between this embodiment and Embodiment 1 is that in step S1, the actual silicon-to-carbon ratio (Si / C) is artificially set to 0.58 to simulate the traditional low silicon-to-carbon ratio process; otherwise, it is exactly the same as Embodiment 1.

[0149] Example 3:

[0150] The difference between this embodiment and Embodiment 1 is that the operation of determining and adjusting the inoculation parameters based on the maximum temperature deviation and the actual silicon-carbon ratio in step S3 is omitted. That is, no silicon carbide adjustment amount is added, and the in-flow barium silicon inoculant addition rate remains unchanged. The rest is exactly the same as Embodiment 1.

[0151] Example 4:

[0152] The difference between this embodiment and Embodiment 1 is that the step of adding silicon carbide inoculant before the molten iron is tapped in step S4 is omitted; otherwise, it is exactly the same as Embodiment 1.

[0153] Example 5:

[0154] The difference between this embodiment and Embodiment 1 is that the step of adding a second dose of barium silicon inoculant during the pouring of molten iron in step S5 is omitted; otherwise, it is exactly the same as Embodiment 1.

[0155] Example 6:

[0156] The difference between this embodiment and Embodiment 1 is that in step S4, the first dose of the barium silicon inoculant is fixed at 0.4% of the weight of the molten iron and is not adjusted according to the actual silicon-carbon ratio and the maximum temperature deviation. The rest is exactly the same as in Embodiment 1.

[0157] Please refer to Table 1 for the performance test results of Examples 1 to 6.

[0158] Table 1 Performance test results of Examples 1 to 6

[0159]

[0160] Analysis of the above experimental results shows that Example 1, employing the complete technical solution of this invention, achieved the best overall performance, exhibiting the highest tensile strength, the most uniform hardness distribution, and no casting defects. This indicates that by precisely setting the silicon-carbon ratio using the wall thickness sensitivity coefficient and combining it with the synergistic mechanism of dynamically adjusting the inoculation parameters based on the molten iron state, the graphite morphology and matrix structure were effectively optimized, achieving the best balance between strength and uniformity. In contrast, Example 2, using a traditional low silicon-carbon ratio formulation, showed a significant decrease in tensile strength, extremely uneven hardness distribution, and a tendency for shrinkage cavities. This fully demonstrates that the low silicon-carbon ratio process leads to system performance degradation due to graphite coarsening, white cast iron tendency, and deterioration of solidification characteristics, highlighting the necessity of this invention's approach of appropriately increasing the silicon-carbon ratio. Example 3, without adjusting the inoculation parameters according to the uniformity of molten iron temperature, showed a decrease in microstructure uniformity, indicating that relying solely on a fixed composition design without real-time response to the melt state is insufficient to fully guarantee microstructure homogeneity. Example 4, lacking pretreatment with silicon carbide inoculant before tapping, showed minimal impact on mechanical properties but exhibited slight shrinkage cavities, revealing the unique role of silicon carbide in improving the nucleation foundation and feeding capacity of molten iron. Example 5, omitting in-flow inoculation, resulted in poorer hardness uniformity, demonstrating that instantaneous inoculation of thin-walled regions during casting is indispensable for suppressing localized undercooling and ensuring overall microstructure consistency. Example 6, using a fixed initial dosage, showed slightly inferior hardness uniformity compared to Example 1, indicating that a dynamic adjustment strategy based on composition and temperature feedback can more precisely match actual metallurgical requirements than a fixed dosage. In summary, the superiority of this invention lies in the close integration of each process step and the synergistic effect of multiple feedback mechanisms. The omission or simplification of any key step may lead to a decline in specific performance indicators; only complete implementation can ensure stable and excellent overall quality of gray cast iron parts.

[0161] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. An optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation, characterized in that, include: Step S1 involves calculating the wall thickness sensitivity coefficient of the casting based on the target size of the casting, and determining the actual silicon-carbon ratio of the casting based on the wall thickness sensitivity coefficient and the silicon-carbon ratio feedback factor. Step S1 includes: Step S11: Determine the maximum and minimum wall thickness of the casting based on the target dimensions of the casting; Step S12: Calculate the wall thickness sensitivity coefficient based on the maximum wall thickness and the minimum wall thickness. The specific formula for calculating the wall thickness sensitivity coefficient is as follows: ； Where K is the wall thickness sensitivity coefficient, which is dimensionless, and its calculation result is retained to one decimal place; d min Minimum wall thickness, in millimeters; d max Maximum wall thickness, in millimeters; Step S13: Determine the actual silicon-carbon ratio based on the wall thickness sensitivity coefficient and the silicon-carbon ratio feedback factor; The actual silicon-to-carbon ratio is determined according to the following rules based on the wall thickness sensitivity coefficient, and the actual silicon-to-carbon ratio is denoted as Si / C: When K ≤ 2.5: Si / C = 0.85 + u, When 2.5 < K ≤ 4.0: Si / C = 0.80 + u, When K > 4.0: Si / C = 0.75 + u; u is the silicon-carbon ratio feedback factor, which is dimensionless and u∈[-0.05,0.05]. The minimum value of the actual silicon-carbon ratio is 0.7 and the maximum value is 0.

9. For the first production of a single batch of castings, the silicon-carbon ratio feedback factor is 0. Step S2: The synthetic cast iron raw materials are added to an electric furnace for melting and the composition is adjusted to the actual silicon-carbon ratio to obtain molten iron. The synthetic cast iron raw materials include scrap steel, scrap castings and silicon carbide. Step S3: Raise the temperature of the molten iron to 1500℃~1550℃ and let it stand for 3~5 minutes. During the standing process, the maximum temperature deviation is detected. Based on the maximum temperature deviation and the actual silicon-carbon ratio, determine the inoculation parameter adjustment data, including the amount of silicon carbide adjustment and the amount of in-flow barium silicon inoculant addition rate adjustment. Step S4: Pour the molten iron into a preheated molten iron treatment ladle, wherein... Based on the aforementioned silicon carbide adjustment amount, a silicon carbide inoculant is added before the molten iron is tapped from the furnace. After the molten iron is tapped from the furnace to the molten iron treatment ladle, a first dose of barium silicon inoculant is added, wherein the first dose of barium silicon inoculant is determined based on a reference first dose, the actual silicon-carbon ratio, and the maximum temperature deviation; Step S5: The molten iron is poured into a casting ladle for casting and molding. A second dose of barium silicon inoculant is added during the pouring of the molten iron into the sand mold, based on the adjusted rate of the in-flow barium silicon inoculant addition. After molding, gray cast iron is obtained. The second dose is determined according to the adjusted rate of the in-flow barium silicon inoculant addition and the first dose. The second dose is negatively correlated with the first dose and positively correlated with the adjusted rate of the in-flow barium silicon inoculant addition. Step S6: Based on the hardness difference between different wall thickness regions of the prepared gray cast iron, the silicon-carbon ratio feedback factor is corrected. Step S6 includes: Step S61: Detect the hardness difference between the hardness of the maximum wall thickness region and the minimum wall thickness region of the gray cast iron sample. Step S62: Compare the hardness difference with the target hardness difference to obtain the performance deviation characterization value; Step S63: Based on the performance deviation characterization value, the silicon-carbon ratio feedback factor is corrected, wherein the silicon-carbon ratio feedback factor correction amount is determined based on the product of the performance deviation characterization value and a preset correction coefficient, and the silicon-carbon ratio feedback factor is updated according to the silicon-carbon ratio feedback factor correction amount.

2. The optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation according to claim 1, characterized in that, Step S3 includes: Step S31: Insert a thermocouple at the start of the settling process and continuously measure the settling temperature data of the molten iron. Step S32: Obtain the maximum temperature deviation based on the static temperature data; Step S33: Based on the maximum temperature deviation, determine whether to adjust the incubation parameters. If it is determined that the incubation parameters should be adjusted, then determine the adjustment amount of the basic silicon carbide and the adjustment amount of the basic in-flow barium silicon incubator addition rate based on the maximum temperature deviation. Step S34: Correct the basic silicon carbide adjustment amount according to the actual silicon-carbon ratio to obtain the silicon carbide adjustment amount; correct the basic in-flow barium silicon inoculant addition rate adjustment amount according to the actual silicon-carbon ratio to obtain the in-flow barium silicon inoculant addition rate adjustment amount.

3. The optimized method for gray cast iron preparation based on silicon-carbon synergistic regulation according to claim 2, characterized in that, In step S33, the maximum temperature deviation is compared with the maximum temperature deviation threshold to determine whether to adjust the gestation parameters. If the maximum temperature deviation is greater than or equal to the maximum temperature deviation threshold, it is determined that the gestation parameters should be adjusted. If the maximum temperature deviation is less than the maximum temperature deviation threshold, it is determined that the gestation parameters should not be adjusted.

4. The optimized method for gray cast iron preparation based on silicon-carbon synergistic regulation according to claim 3, characterized in that, In step S4, the adjustment direction of the reference first dose is determined according to the actual silicon-carbon ratio, and the adjustment range of the reference first dose is determined according to the maximum temperature deviation, thus obtaining the first dose.

5. The optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation according to claim 1, characterized in that, The synthetic cast iron raw materials, by weight, include 60 to 80 parts scrap steel, 20 to 40 parts scrap castings, and 0.8 to 1.2 parts silicon carbide.

6. The optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation according to claim 5, characterized in that, The particle size of silicon carbide is 1 mm to 5 mm; the particle size of silicon carbide inoculant is 0.2 mm to 1 mm; the particle size of the first added barium silicon inoculant is 3 mm to 10 mm; and the particle size of the second added barium silicon inoculant is 0.2 mm to 0.8 mm.

7. The optimized method for preparing gray cast iron based on silicon-carbon synergistic regulation according to claim 6, characterized in that, In step S5, the pouring temperature is 1380℃~1420℃, and the pouring time is less than or equal to 10 minutes.

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