Alloy ductile iron profile for aluminum die-casting mold and preparation method thereof

Abstract

The present application relates to the technical field of horizontal continuous casting cast iron profiles, and specifically discloses an alloy ductile iron profile for aluminum die-casting molds and a preparation method thereof, wherein the preparation method of the alloy ductile iron profile comprises the following steps: smelting raw materials at 1450-1650°C to obtain molten iron; pouring the molten iron into a spheroidizing bag to which 0.4-0.6wt% of a spheroidizing agent and 0.4-0.6wt% of an inoculant have been pre-added, based on the total weight of the raw materials, and then entering a spheroidizing station for wire feeding and spheroidizing treatment, removing slag from the molten iron in the bag, and then injecting the molten iron into a heat-insulating crystallization furnace of a horizontal continuous casting production line; after cooling the molten iron, gradually pulling, cutting, and pressing to obtain an alloy ductile iron profile slab, wherein the spheroidization rate and the number density of graphite balls of the obtained alloy ductile iron profile are as high as 89.63% and 778 pieces / mm, respectively. 2 , the graphite spheroidization effect is good, which improves the aluminum liquid corrosion resistance of alloy ductile iron materials.

Description

Technical Field

[0001] The present application relates to the technical field of horizontal continuous casting cast iron profiles, and more specifically, to an alloy ductile iron profile for aluminum die-casting molds and a preparation method thereof. Background Art

[0002] In recent years, with the vigorous development of the aluminum die-casting industry, the consumption of mold profiles required for aluminum die-casting production has increased year by year, and the quality requirements have become increasingly higher. At present, there are few steel mills in the world that have the ability to produce high-end mold profiles, and their prices are generally above 40,000 yuan / ton. Domestic mold profiles are relatively cheap, but the product quality and stability still have a certain gap with similar foreign products.

[0003] Alloy ductile iron profiles are materials that combine high toughness with a variety of special performance properties and possess excellent casting and molding processability. Ductile iron has good comprehensive properties and can achieve near-net forming. It can be used not only to manufacture grinding balls, but also to manufacture mold profiles.

[0004] The aluminum die-casting industry's production costs are significantly impacted by mold customization, usage, and maintenance. The quality of the mold directly determines the quality of the finished aluminum product. Key issues with aluminum die-casting molds include corrosion, adhesion, and rapid wear of the mold cavity during processing. Corrosion and adhesion of molten aluminum can lead to erosion marks, pits, and burrs within the mold cavity, resulting in poor quality finished aluminum products.

[0005] In the related art, the quality of mold profiles is mainly improved by increasing the purity of the mold profiles. However, this results in high prices for the raw materials of the mold profiles, as well as high operating and maintenance costs, which are difficult to meet the actual needs. Summary of the Invention

[0006] In order to improve the aluminum liquid corrosion resistance of alloy ductile iron profiles, the present application provides a preparation method of alloy ductile iron profiles for aluminum die-casting molds.

[0007] In a first aspect, the present application provides a method for preparing an alloy ductile iron profile for an aluminum die-casting mold, which adopts the following technical solution:

[0008] A method for preparing an alloy ductile iron profile for an aluminum die-casting mold comprises the following steps:

[0009] S1: Smelting the raw materials at 1450-1650°C to obtain molten iron;

[0010] S2: Based on the total weight of the raw materials, the molten iron is poured into a spheroidizing bag pre-added with 0.4-0.6wt% of spheroidizing agent and inoculant, and then enters the spheroidizing station for wire feeding and spheroidizing treatment. The molten iron in the bag is slag-removed, and then the molten iron is injected into the heat-insulating crystallization furnace of the horizontal continuous casting production line;

[0011] S3: After the molten iron is cooled, it is gradually pulled, cut and pressed to obtain alloy ductile iron profile slabs.

[0012] Through the above technical solution, the raw materials are first heated and smelted at 1450-1650°C to obtain molten iron, and then the molten iron is spheroidized to inoculate the graphite in the cast iron into spheres, thereby improving the utilization rate of the metal matrix strength, minimizing the cutting effect of the matrix, and blocking or delaying the erosion and wear of the matrix material by the aluminum liquid. After the molten iron is cooled, the obtained profile is cut and pressed to obtain the alloy ductile iron profile slab.

[0013] Preferably, the spheroidizing agent in step S2 is a silicon carbide spheroidizing agent; and the inoculant in step S2 is a Y-Ba inoculant.

[0014] Through the above technical solution, the spheroidizing agent is silicon carbide. During the solidification process, the silicon produced by the silicon carbide dissolves in the austenite, and a part of the carbon produced melts in the austenite. The other part fluctuates due to composition and energy. When the carbon atom clusters formed exceed the critical crystal nucleus size, the carbonaceous crystal nuclei of spherical graphite are directly formed in the molten iron; the dispersed silicon carbide particles act as heterogeneous crystal nuclei in the molten iron; some composite metal oxides with low lattice matching adaptability can also become heterogeneous nuclei of spherical graphite.

[0015] The inoculant containing Y element has excellent S removal ability and high temperature resistance to spheroidization decay. The high melting point compound that can be formed can serve as the heterogeneous core of graphite, which promotes a significant increase in the number of spherical graphite and a reduction in the spherical diameter, which is conducive to floating from the molten iron and significantly delays the time of spheroidization decay. The addition of Ba element can increase the number of graphite cores, promote graphitization, prolong the spheroidization decay time, and promote the formation of nucleation refinement.

[0016] The two together promote the spheroidization of molten iron, which can block or delay the corrosion and wear of the base material by the aluminum liquid, and improve the resistance of alloy ductile iron profiles to aluminum liquid corrosion.

[0017] Preferably, the purity of the silicon carbide is ≥95%.

[0018] Through the above technical solution, silicon carbide can become the nucleus for the formation of spherical graphite, promoting the reduction of the diameter of the graphite spheres, increasing the number, and making the shape round; in addition, silicon carbide reacts with the metal oxides in the molten iron to form composite oxides, which are easily floated to the surface and removed in the molten iron, thereby purifying the molten iron; therefore, high-purity silicon carbide purifies the molten iron and enhances the spheroidization effect, thereby improving the resistance of alloy ductile iron profiles to aluminum liquid corrosion.

[0019] Preferably, the lengths of the spheroidizing line and the inoculating line for feeding the yarn spheroidizing in step S2 are both 15-20 m.

[0020] Through the above technical solution, the length of the spheroidizing line and the inoculation line is controlled to 15-20m, which can extend the spheroidizing time, allow the molten iron to be fully spheroidized, improve the spheroidizing efficiency, and further improve the alloy ductile iron profile's resistance to aluminum liquid corrosion.

[0021] Preferably, the wire feeding speed in step S2 is 20-30 m / min.

[0022] Through the above technical solution, the wire feeding speed is controlled at 20-30m / min, which can fully spheroidize the molten iron, increase the number of spheroidizations, adjust the spheroidization spacing, and further improve the aluminum liquid corrosion resistance of the alloy ductile iron profile.

[0023] Preferably, the step S2 further includes a Si-Y-Sb synchronous inoculation line.

[0024] Through the above technical solution, Si-Y-Sb synchronous inoculation line is added to accumulate Sb around the ductile graphite, inhibiting the formation of ferrite; avoiding the appearance of flocculent graphite, increasing the number of spheroidization and the roundness of the morphology, and improving the aluminum liquid corrosion resistance of the alloy ductile iron profile.

[0025] Preferably, the cooling in step S3 includes graphite crystallizer cooling and secondary water spray cooling.

[0026] Through the above technical solution, cooling the molten iron through a graphite crystallizer and secondary water spray cooling can promote the number of graphite cores and the refinement of the matrix structure, increase the number of graphite balls, and improve the resistance of alloy ductile iron profiles to aluminum liquid corrosion.

[0027] Preferably, the cooling rate of the graphite crystallizer is 1-2°C / s.

[0028] Through the above technical solution, the cooling rate of the graphite crystallizer is controlled to 1-2℃ / s, which can accelerate the cooling rate, make the ductile iron structure dense, increase the number of graphite nodules, and further improve the aluminum liquid corrosion resistance of the alloy ductile iron profile.

[0029] In a second aspect, the present application provides an alloy ductile iron profile for an aluminum die-casting mold.

[0030] An alloy ductile iron profile for an aluminum die-casting mold comprises the following chemical components in percentage by weight: 3.6≤C≤3.8wt%, 1.2≤Si≤1.4wt%, Mn≤0.20wt%, P≤0.050wt%, S≤0.020wt%, Ni≥1.2wt%, Cr≤0.8wt%, Mo≥1.5wt%, V≥1.2wt%, Al≥2.0wt%, and the balance is iron and unavoidable impurities.

[0031] Through the above technical solution, carbon (C): carbon is the basic element of ductile iron, which can promote the fluidity of molten iron. The carbon element is beneficial to spheroidization, increases the precipitation of graphite during solidification, increases the volume expansion of graphitization to compensate for shrinkage, increases the density of castings, and improves mechanical properties.

[0032] Silicon (Si): Silicon promotes graphitization, improves the roundness of graphite, crystallizes it, and decomposes cementite. Therefore, increasing the silicon content reduces the diameter of graphite nodules, increases their number, and improves their roundness. It also increases ferrite and reduces pearlite, reducing strength and hardness while increasing plasticity and toughness. Silicon strengthens ferrite and shifts the eutectic point to the upper left, narrowing the solidification range, increasing fluidity, and reducing shrinkage. It also raises the eutectic transition temperature of molten iron and reduces the tendency toward white cast iron. Appropriately increasing the silicon content narrows the solidification temperature range of molten iron, improves fluidity, and reduces shrinkage.

[0033] Manganese (Mn): Manganese lowers the eutectoid transition temperature, thereby stabilizing and refining the pearlite structure and preventing pearlite decomposition during graphitization. Manganese promotes cementite formation; increasing the manganese content increases strength while decreasing plasticity and toughness. When a high concentration of free cementite is present in the structure, all other properties, except hardness, decrease. Manganese increases the stability of supercooled austenite, shifting the S-curve to the right.

[0034] Phosphorus (P): Phosphorus is a harmful element. Its solubility in cast iron is extremely low. When its content is less than 0.05%, it dissolves in the matrix and has little effect on mechanical properties. When its content exceeds 0.05%, phosphorus easily segregates at the boundaries of eutectic cells, forming binary, ternary, or composite phosphorus eutectics, which reduces the toughness of the cast iron. Phosphorus raises the ductile-brittle transition temperature of cast iron. As the phosphorus content increases, shrinkage cavities and porosity increase.

[0035] Sulfur (S): Sulfur is an anti-spheroidizing element. It has a strong affinity for spheroidizing elements such as magnesium and rare earth elements. The presence of sulfur will consume a large amount of spheroidizing elements in the molten iron, forming magnesium and rare earth sulfides, which can cause casting defects such as slag inclusions and porosity. The sulfur content in ductile iron is generally required to be less than 0.06%.

[0036] Nickel (Ni): Adding Ni element alloying can improve the corrosion resistance of ductile iron, significantly increase the hardness, and slightly reduce the impact toughness.

[0037] Chromium (Cr): The addition of Cr can increase the hardness of the material and promote the transformation of pearlite during the eutectoid transformation, stabilize and refine the pearlite, and improve the quality of ductile iron;

[0038] Molybdenum (Mo): The addition of Mo can improve the stability of ductile iron structure and refine pearlite, thereby improving the quality of ductile iron. Adding molybdenum or chromium to ductile iron can improve the tensile strength, yield strength, elongation, and hardness of ductile iron due to the solid solution strengthening and grain refinement effects of the alloying elements. The strength-enhancing effect of adding chromium is more pronounced than that of adding molybdenum, and the effect is most pronounced when both molybdenum and chromium are added simultaneously.

[0039] Vanadium (V): Vanadium can be embedded in the cast iron matrix, significantly improving the properties of ductile iron. Vanadium is a cast iron strengthening element, and as the vanadium content increases, the tensile strength of the cast iron also increases. In ductile iron, every 0.1% increase in V increases the strength by 30-40 MPa.

[0040] Aluminum (Al): As the aluminum content increases, the aluminum element will dissolve in the ferrite matrix, playing a role of solid solution strengthening, resulting in increased strength; aluminum can reduce the austenite phase area, adjust the ferrite content in cast iron, increase the activity of carbon, and promote graphite nucleation.

[0041] Preferably, the alloy ductile iron profile for aluminum die-casting mold is characterized in that it includes the following chemical components in weight percentage: 3.6≤C≤3.8wt%, 1.2≤Si≤1.4wt%, Mn≤0.20wt%, P≤0.030wt%, S≤0.010wt%, Ni≥1.2wt%, Cr≤0.8wt%, Mo≥1.5wt%, V≥1.2wt%, 2.0≤Al≤10.0wt%, and the balance is iron and unavoidable impurities.

[0042] Through the above technical solution, the mass percentage of aluminum content is controlled to be 2.0≤Al≤10.0wt%, which can further improve the ferrite content in the cast iron, promote graphite nucleation, and enhance spheroidization.

[0043] In summary, this application includes at least one of the following beneficial technical effects:

[0044] (1) The present application prepares a process of melting raw materials at elevated temperatures, spheroidizing the obtained molten iron in a spheroidizing bag containing a spheroidizing agent and an inoculant, feeding the molten iron with wire, and then cooling the molten iron in a heat-insulating crystallization furnace of a horizontal continuous casting production line; gradually pulling, cutting, and breaking the molten iron to obtain alloy ductile iron profile slabs, wherein the spheroidization rate and the number density of graphite balls of the obtained alloy ductile iron profiles are as high as 89.63% and 778 / mm, respectively. 2The graphite spheroidization effect of ductile iron is good, and there is no aluminum liquid corrosion phenomenon, which improves the aluminum liquid corrosion resistance of alloy ductile iron materials.

[0045] (2) By adjusting the content of chemical elements in the raw materials, the spheroidization rate and the number density of graphite balls obtained by this application are 85.23% and 559 / mm respectively. 2 , and no aluminum liquid corrosion phenomenon occurs, which further improves the graphite spheroidization effect of ductile iron, thereby improving the aluminum liquid corrosion resistance of alloy ductile iron materials.

[0046] (3) The present invention uses silicon carbide spheroidizing agent and Y-Ba inoculant, and when the purity of silicon carbide is ≥95%, the spheroidization rate and graphite ball number density of the alloy ductile iron profile obtained are 86.69% and 601 / mm respectively. 2 , and there is no aluminum liquid corrosion phenomenon, which improves the graphite spheroidization effect of ductile iron, and further improves the aluminum liquid corrosion resistance of alloy ductile iron materials.

[0047] (4) By controlling the length of the spheroidizing line and the inoculation line to be 15-20 m, the spheroidizing rate and the number density of graphite balls of the alloy ductile iron profile obtained are 87.03-87.65% and 615-631 per mm, respectively. 2 , and there is no aluminum liquid corrosion phenomenon, which improves the graphite spheroidization effect of ductile iron, and further improves the aluminum liquid corrosion resistance of alloy ductile iron materials.

[0048] (5) By controlling the wire feeding speed, the spheroidization rate and graphite ball density of the alloy ductile iron profile obtained by the present invention are 88.16% and 685 / mm respectively. 2 , and there is no aluminum liquid corrosion phenomenon, which improves the graphite spheroidization effect of ductile iron, and further improves the aluminum liquid corrosion resistance of alloy ductile iron materials.

[0049] (6) The spheroidization rate and number density of graphite balls of the alloy ductile iron profile obtained by adding Si-Y-Sb synchronous inoculation wire are 88.53% and 718 / mm respectively. 2 , and there is no aluminum liquid corrosion phenomenon, which improves the graphite spheroidization effect of ductile iron, and further improves the aluminum liquid corrosion resistance of alloy ductile iron materials.

[0050] (7) The present invention adjusts the cooling process including cooling of the graphite crystallizer and secondary water spray cooling, and controls the cooling speed of the graphite crystallizer, so that the spheroidization rate and the number density of graphite balls of the alloy ductile iron profile are 89.63% and 778 / mm respectively. 2, and there is no aluminum liquid corrosion phenomenon, which improves the graphite spheroidization effect of ductile iron, and further improves the aluminum liquid corrosion resistance of alloy ductile iron materials.

[0051] Figures in the specification

[0052] Figure 1 For this application, the ablation test device;

[0053] Figure 2 This is a metallographic diagram of the ablation produced by comparative example 1 of the present application;

[0054] Figure 3 This is a graph of the corrosion rates of the hot working die profiles of the alloy ductile iron profiles of Example 1, Example 21 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0055] The present application is further described in detail below with reference to specific embodiments.

[0056] The following raw materials in this application are all commercially available products. They are provided to fully disclose the raw materials in this application and should not be construed as limiting the sources of the raw materials. Specifically:

[0057] The particle size of the magnesium metal spheroidizer is 10-35 mm, and the particle size of the silicon-calcium inoculant is 8-15 mm.

[0058] Example 1

[0059] The alloy ductile iron profile of Example 1 is prepared by the following preparation method:

[0060] S1: In a 2T one-to-two medium frequency melting furnace, Q10 pig iron (pig iron element content: 4.3-4.5wt% C, 0.9-1.0wt% Si, Mn≤0.20wt%, P≤0.050wt%, S≤0.020wt%), high-quality scrap steel, 75% ferrosilicon (FeSi75-A), nickel plate, 60% ferrochrome (FeCr60), 60% ferromolybdenum (FeMo60), 50% ferrovanadium (FeV50), aluminum ingots and other raw materials are added according to the proportion of element content in Table 1, and smelted at 1550°C to obtain molten iron;

[0061] S2: Based on the total weight of the raw materials, the molten iron is poured into a spheroidizing bag to which 0.5wt% of a spheroidizing agent (magnesium metal spheroidizing agent) and 0.5wt% of an inoculant (silicon-calcium inoculant) have been added in advance. The molten iron then enters the spheroidizing station for wire feeding and spheroidizing treatment. The length of the spheroidizing and inoculating lines is 14m, and the wire feeding speed is 18m / min. The molten iron in the bag is slag-removed, and then the molten iron is injected into the heat-insulating crystallization furnace of the horizontal continuous casting production line;

[0062] S3: After the molten iron is cooled by spraying water, it is gradually pulled, cut and pressed to obtain alloy ductile iron profile slabs with a fixed length of 3m and a cross-sectional size of 400*80mm.

[0063] Examples 2-6

[0064] The preparation methods of the alloy ductile iron profiles of Examples 2-6 are the same as those of Example 1, except that the element contents are different, as shown in Table 1 for details.

[0065] Table 1 Element content (wt%) of alloy ductile iron profiles of Examples 1-6

[0066]

[0067] Example 7

[0068] The preparation method of the alloy ductile iron profile of Example 7 is the same as that of Example 5, except that the spheroidizing agent is different, that is, the spheroidizing agent uses silicon carbide with a purity of 90%.

[0069] Example 8

[0070] The preparation method of the alloy ductile iron profile of Example 8 is the same as that of Example 7, except that the purity of the spheroidizing agent silicon carbide is different, and the purity of silicon carbide is 95%.

[0071] Example 9

[0072] The preparation method of the alloy ductile iron profile of Example 9 is the same as that of Example 8, except that the inoculant is different, that is, the inoculant is Y-Ba inoculant.

[0073] Examples 10-13

[0074] The preparation method of the alloy ductile iron profiles of Examples 10-13 is the same as that of Example 9, except that the lengths of the spheroidizing line and the inoculant line are different. See Table 2 for details.

[0075] Table 2 Process parameters for preparing alloy ductile iron profiles of Examples 10-13

[0076] Example 10 Example 11 Example 12 Example 13 Spheroidizing line length / m 15 17.5 20 21 Inoculant line length / m 15 17.5 20 21

[0077] Examples 14-17

[0078] The preparation method of the alloy ductile iron profiles of Examples 14-17 is the same as that of Example 11, except that the wire feeding speed is different. See Table 3 for details.

[0079] Table 3 Process parameters for the preparation of alloy ductile iron profiles of Examples 14-17

[0080] Example 14 Example 15 Example 16 Example 17 Spheroidizing line length / m 17.5 17.5 17.5 17.5 Inoculant line length / m 17.5 17.5 17.5 17.5 Wire feeding speed / m / min 20 25 30 32

[0081] Example 18

[0082] The preparation method of the alloy ductile iron profile of Example 18 is the same as that of Example 15, except that step S2 also includes a Si-Y-Sb synchronous inoculation line.

[0083] Example 19

[0084] The preparation method of the alloy ductile iron profile of Example 19 is the same as that of Example 18, except that the cooling method adopts graphite crystallizer cooling and secondary water spray cooling, and the cooling rate is 0.5°C / s

[0085] Examples 20-23

[0086] The preparation method of the alloy ductile iron profiles of Examples 20-23 is the same as that of Example 19, except that the cooling speed is different. See Table 4 for details.

[0087] Table 4 Process parameters for the preparation of alloy ductile iron profiles of Example 20-23

[0088] Example 20 Example 21 Example 22 Example 23 Spheroidizing line length / m 17.5 17.5 17.5 17.5 Inoculant line length / m 17.5 17.5 17.5 17.5 Wire feeding speed / m / min 25 25 25 25 Cooling rate / ℃ / s 1 1.5 2 2.5

[0089] Comparative Example 1

[0090] The preparation method of the alloy ductile iron profile of Comparative Example 1 is the same as that of Example 1, except that the amount of spheroidizing agent used is 0.3 wt % and the types and amounts of other raw materials are the same as those of Example 1.

[0091] Comparative Example 2

[0092] The preparation method of the alloy ductile iron profile of Comparative Example 2 is the same as that of Example 1, except that the amount of spheroidizing agent used is 0.7 wt %. The types and amounts of other raw materials are the same as those of Example 1.

[0093] Comparative Example 3

[0094] The preparation method of the alloy ductile iron profile of Comparative Example 3 is the same as that of Example 1, except that the amount of the inoculant is 0.3 wt % and the types and amounts of other raw materials are the same as those of Example 1.

[0095] Comparative Example 4

[0096] The preparation method of the alloy ductile iron profile of Comparative Example 4 is the same as that of Example 1, except that the amount of the inoculant is 0.7 wt % and the types and amounts of other raw materials are the same as those of Example 1.

[0097] Performance test (I)

[0098] The spheroidization rate and graphite number density of the alloy ductile iron profile samples obtained in different Examples 1-23 and Comparative Examples 1-4 were tested using GB / T 9441-2021 ductile iron metallographic inspection combined with an image analyzer. The test samples were prepared from four surface positions and the center of the ductile iron parts, and the average value was taken. The test results are shown in Table 5.

[0099] In alloy ductile iron, the number of graphite balls represents the effect of spheroidization. The more graphite balls there are, the higher the graphite ball spheroidization rate is, the better the roundness of the graphite balls is, the more uniform the graphite size is, and the smaller the distance between the graphite balls is. The erosion rate of the die-casting mold made of alloy ductile iron profiles is affected by the number of graphite balls in the matrix material. The more graphite balls there are, the lower the erosion rate is.

[0100] The alloy ductile iron profile samples obtained in Examples 1-23 and Comparative Examples 1-4 were made into die-casting mold inserts, and the following were made: Figure 1 The corrosion test device shown is used to observe whether aluminum liquid corrosion occurs when the die-casting mold is used continuously at 500°C.

[0101] Table 5 Graphite spheroidization effect of ductile iron of Examples 1-23 and Comparative Examples 1-4

[0102] Spheroidization rate / % <![CDATA[Graphite sphere number density / number / mm 2 > Whether aluminum melt corrosion occurs Example 1 84.12 513 no Example 2 84.49 528 no Example 3 84.09 512 no Example 4 84.86 544 no Example 5 85.23 559 no Example 6 84.82 542 no Example 7 85.96 590 no Example 8 86.33 605 no Example 9 86.69 601 no Example 10 87.06 616 no Example 11 87.65 631 no Example 12 87.03 615 no Example 13 86.66 639 no Example 14 87.80 667 no Example 15 88.16 685 no Example 16 87.76 682 no Example 17 87.39 670 no Example 18 88.53 718 no Example 19 88.90 748 no Example 20 89.27 761 no Example 21 89.63 778 no Example 22 89.23 764 no Example 23 88.86 758 no Comparative Example 1 80.82 375 yes Comparative Example 2 79.72 329 yes Comparative Example 3 78.98 298 yes Comparative Example 4 78.62 283 yes

[0103] The test results in Table 5 show that the spheroidization rate, ball diameter and number density of the alloy ductile iron profile obtained in this application are the highest at 89.63%, 778 / mm and 10.83% respectively. 2 The graphite spheroidization effect of ductile iron is good, and there is no aluminum liquid corrosion phenomenon, which improves the aluminum liquid corrosion resistance of alloy ductile iron materials.

[0104] In Examples 1-6, the spheroidization rate and the number density of graphite nodules of the alloy ductile iron profile obtained in Example 2 were 84.49% and 528 / mm respectively. 2 The spheroidization rate and number density of graphite balls of the alloy ductile iron profile obtained in Example 5 were 85.23% and 559 / mm 2 , and there was no aluminum liquid corrosion phenomenon, which shows that adjusting the content of chemical elements in the raw materials can promote the graphite spheroidization effect of ductile iron.

[0105] In combination with Examples 6-7, the spheroidization rate and graphite ball density of the alloy ductile iron profile obtained in Example 7 were 85.96% and 590 / mm respectively. 2, higher than that of Example 6, and no aluminum erosion occurred in either case. This indicates that the use of silicon carbide spheroidizer is more suitable, improving the graphite spheroidization effect of the alloy ductile iron profile, thereby improving the alloy ductile iron's resistance to aluminum erosion. This may be related to the use of silicon carbide spheroidizer, which can promote nucleation.

[0106] In combination with Examples 7-8, the spheroidization rate and graphite ball density of the alloy ductile iron profile obtained in Example 8 were 86.33% and 603 / mm respectively. 2 , higher than that of Example 7, and no aluminum corrosion was observed in either case. This indicates that a silicon carbide purity of 95% or higher is optimal, improving the graphite spheroidization of the alloy ductile iron profile, thereby enhancing the alloy ductile iron's resistance to aluminum corrosion. This may be related to the fact that a silicon carbide purity of 95% or higher can purify the molten iron and enhance the spheroidization effect.

[0107] In combination with Examples 8-9, the spheroidization rate and graphite ball density of the alloy ductile iron profile obtained in Example 9 were 86.69% and 601 / mm respectively. 2 , higher than that of Example 8, and no aluminum corrosion was observed in either case. This indicates that the Y-Ba inoculant is more suitable, improving the graphite spheroidization of the alloy ductile iron profile and, in turn, the alloy ductile iron's resistance to aluminum corrosion. This may be due to the Y-Ba inoculant promoting nucleation refinement.

[0108] In combination with Examples 9 and 10-13, the spheroidization rate and the number density of graphite nodules of the alloy ductile iron profiles obtained in Examples 10-12 were 87.03-87.65% and 615-631 / mm respectively. 2 , higher than that of Examples 9 and 13, and no aluminum molten corrosion occurred in either case. This indicates that a 15-20m length for both the spheroidizing and inoculating lines is more suitable, improving the graphite spheroidization effect of the alloy ductile iron profiles and, in turn, the alloy ductile iron's resistance to aluminum molten corrosion. This may be related to the fact that a 15-20m length for both the spheroidizing and inoculating lines can improve the graphite spheroidization efficiency of ductile iron.

[0109] In combination with Examples 11 and 14-17, the spheroidization rate and the number density of graphite nodules of the alloy ductile iron profiles obtained in Examples 14-16 were 87.76-88.16% and 667-685 per mm, respectively. 2 , higher than Examples 11 and 17, and no aluminum molten corrosion was observed in either case. This indicates that controlling the wire feeding speed in step S2 to 20-30 m / min is more suitable, improving the graphite spheroidization of the alloy ductile iron profile and, in turn, its resistance to aluminum molten corrosion. This may be related to the fact that controlling the wire feeding speed in step S2 can increase the number of spheroidization balls and adjust the spacing between spheroidization balls.

[0110] In combination with Examples 15 and 18, the spheroidization rate and the number density of graphite balls of the alloy ductile iron profile obtained in Example 18 were 88.53% and 718 / mm respectively. 2 , higher than that of Example 15, and no aluminum corrosion occurred, indicating that the inclusion of a Si-Y-Sb simultaneous inoculation line in Step S2 is more suitable, improving the graphite spheroidization of the alloy ductile iron profile and, in turn, its resistance to aluminum corrosion. This may be related to the inclusion of a Si-Y-Sb simultaneous inoculation line in Step S2, which can increase the number of spheroidized particles and the roundness of the morphology.

[0111] In combination with Examples 18 and 19, the spheroidization rate and graphite ball density of the alloy ductile iron profile obtained in Example 19 were 88.90% and 748 / mm respectively. 2 , higher than Example 18, and no aluminum molten corrosion occurred, indicating that step S3 cooling, including graphite mold cooling and secondary water spray cooling, is more suitable. It improves the graphite spheroidization effect of the alloy ductile iron profile, thereby improving the alloy ductile iron's resistance to aluminum molten corrosion. This may be related to the fact that step S3 cooling, including graphite mold cooling and secondary water spray cooling, can increase the number of graphite nodules.

[0112] In combination with Examples 19-23, the spheroidization rate and the number density of graphite balls of the alloy ductile iron profiles obtained in Examples 20-22 were 89.23-89.63% and 761-778 per mm, respectively. 2 , higher than in Examples 19 and 23, and no aluminum erosion occurred in either case. This indicates that controlling the cooling rate of the graphite crystallizer to 1-2°C / s is more appropriate, improving the graphite nodularization of the alloy ductile iron profile and, in turn, its resistance to aluminum erosion. This may be related to controlling the cooling rate of the graphite crystallizer to increase the number of graphite nodules.

[0113] In addition, combined with the various index data of the alloy ductile iron profiles of comparative examples 1-4 and embodiment 1, it is found that the application of too high or too low dosage of the spheroidizing agent and the inoculant will affect the graphite spheroidization effect of the alloy ductile iron profile, resulting in the occurrence of aluminum liquid corrosion. The mold insert made of the alloy ductile iron profile that produced corrosion in comparative example 1 was subjected to metallographic testing, and the test results are as follows: Figure 2 As shown in the figure, the aluminum liquid corrodes the interface, forming a clear boundary between the graphite balls, and the distance between the graphite balls is ≈2*d (graphite ball diameter). This shows that the graphite balls and the distance between them can form a barrier sufficient to slow the corrosion rate of the aluminum liquid. The more graphite balls there are, the higher the nodularity rate is, and the less aluminum liquid corrosion is.

[0114] Performance Testing (II)

[0115] Aiming at the aluminum liquid corrosion phenomenon caused by the working conditions of die casting mold, such as Figure 1 The ablation test device shown in FIG. 1 was used to test the ductile iron profiles and H13 hot working die profiles of Example 1, Example 21 and Comparative Example 1. Figure 3 Results shown.

[0116] Depend on Figure 3 It can be concluded that the increase in the number of graphite balls in the alloy ductile iron profile material has a significant improvement in the anti-corrosion effect of the aluminum die-casting mold material, among which Example 21 (the number of graphite balls is 778 / mm 2 ) alloy ductile iron profile material has the lowest corrosion rate.

[0117] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for preparing an alloy ductile iron profile for an aluminum die-casting mold, characterized in that: The steps include: S1: Smelting the raw materials at 1450-1650°C to obtain molten iron; S2: Based on the total weight of the raw materials, the molten iron is poured into a spheroidizing bag pre-added with 0.4-0.6wt% of a spheroidizing agent and 0.4-0.6wt% of an inoculant, and then enters the spheroidizing station for wire feeding and spheroidizing treatment. The molten iron in the bag is slag-removed, and then the molten iron is injected into the heat-insulating crystallization furnace of the horizontal continuous casting production line; S3: After the molten iron is cooled, it is gradually pulled, cut, and pressed to obtain alloy ductile iron profile slabs; The spheroidizing agent in step S2 is silicon carbide; the inoculant in step S2 is Y-Ba inoculant.

2. The method for preparing an alloy ductile iron profile for an aluminum die-casting mold according to claim 1, wherein: The purity of the silicon carbide is ≥95%.

3. The method for preparing an alloy ductile iron profile for an aluminum die-casting mold according to claim 1, wherein: The lengths of the spheroidizing line and the inoculating line for feeding the yarn spheroidizing in step S2 are both 15-20 m.

4. The method for preparing an alloy ductile iron profile for an aluminum die-casting mold according to claim 1, wherein: The wire feeding speed in step S2 is 20-30 m / min.

5. The method for preparing alloy ductile iron profile for aluminum die-casting mold according to claim 1, characterized in that: The step S2 also includes a Si-Y-Sb synchronous inoculation line.

6. The method for preparing alloy ductile iron profile for aluminum die-casting mold according to claim 1, characterized in that: The cooling in step S3 includes graphite crystallizer cooling and secondary water spray cooling.

7. The method for preparing the alloy ductile iron profile for aluminum die-casting mold according to claim 6, characterized in that: The cooling speed of the graphite crystallizer is 1-2°C / s.

8. An alloy ductile iron profile for aluminum die-casting mold, characterized in that: It includes the following chemical components in weight percentage: 3.6≤C≤3.8wt%, 1.2≤Si≤1.4wt%, Mn≤0.20wt%, P≤0.050wt%, S≤0.020wt%, Ni≥1.2wt%, Cr≤0.8wt%, Mo≥1.5wt%, V≥1.2wt%, Al≥2.0wt%, and the balance is iron and unavoidable impurities.

9. The alloy ductile iron profile for aluminum die-casting mold according to claim 8, characterized in that: It includes the following chemical components in weight percentage: 3.6≤C≤3.8wt%, 1.2≤Si≤1.4wt%, Mn≤0.20wt%, P≤0.030wt%, S≤0.010wt%, Ni≥1.2wt%, Cr≤0.8wt%, Mo≥1.5wt%, V≥1.2wt%, 2.0≤Al≤10.0wt%, and the balance is iron and unavoidable impurities.

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