Pouring process and pouring system of disc casting and product manufactured by pouring process and pouring system

Abstract

The invention discloses a pouring process and a pouring system of a disc casting and a product prepared by the pouring process and the pouring system, and belongs to the technical field of scroll plate processes. According to the method, a horizontal top riser process is adopted, molten iron containing a vermicular iron material enters a cavity through an inner pouring gate and a top riser, the pouring temperature is 1410-1430 DEG C, and the pouring time of a single ladle of molten iron is controlled within 10 min. And in the pouring process, the tangential speed of molten iron mold filling is controlled to be smaller than 1.2 m / s. According to the pouring technology, a horizontal top riser technology is adopted, the feeding pressure of a top riser is large, the feeding effect is good, the higher error-tolerant rate is achieved in the production process, and the interior of a casting is compact and free of the defects of shrinkage porosity, shrinkage cavities and the like. The mechanical properties of the prepared casting meet the conditions that the tensile strength is larger than or equal to 450 MPa, and the yield strength is larger than or equal to 315 MPa; the disc end face vermicularizing rate of the disc casting is larger than or equal to 60%, the center thin wall vermicularizing rate is larger than or equal to 40%, and the disc casting has high mechanical performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of vortex disk technology, and more specifically, relates to a casting process and a casting system for disk castings and products obtained therefrom. Background Art

[0002] Generally, disk castings include a disk end face and an outer cylindrical surface, with a through hole in the middle of the disk end face. The application conditions of disk castings are that they come into contact and collide with other parts under the action of overturning moment, especially the disk end face of disk castings, which frequently comes into contact and collide with other parts. Currently, the commonly used material for disk castings is QT400, which has weak wear resistance and poor mechanical properties, which seriously affects the service life of disk castings.

[0003] In general casting processes, shrinkage feed risers are usually set at the hot spot. However, the hot spot of disc castings is located in the middle of the shaft hole, that is, the hot spot is located in the thick center, which makes it impossible to set shrinkage feed risers at the hot spot. This leads to serious shrinkage at the hot spot of disc castings, which in turn affects the performance of the casting.

[0004] After searching, patent CN117070832A discloses a movable plate casting and smelting process made of vermicular iron 450 material, which belongs to the field of casting technology. The composition of the movable plate casting material is composed of the following elements in mass percentage: C, Si, The invention solves the problem of low performance of existing movable fixed discs. The movable fixed disc casting material is smelted and cast to obtain movable fixed disc castings, which are alloyed with copper-tin alloy and inoculated with 75 ferrosilicon and rare earth silicon-barium inoculants. The strength, hardness and wear resistance of the vermicular iron material can be improved, and the performance of the movable fixed disc casting can reach 450MPa, thereby improving the service life. The patent does not disclose the casting system of the disc casting, and the structure of the casting system is closely related to the performance of the casting finally formed.

[0005] Patent CN117399564A discloses a high-strength and toughness vermicular graphite cast iron scroll disk process, including the following steps: S1: Melting molten iron in a smelting furnace, and transferring the molten iron to a wire feeding station when the molten iron meets the requirements, S3: Pouring molten iron after wire feeding, S4: Pour the molten iron through a pouring cup, and enter the mold cavity through a riser to form a casting, S5: After pouring, unpack after cooling on a cooling line. S6: Cool and separate after unpacking, and finally grind and polish. The vermicular method adopts wire feeding cored wire, and the inoculation process adopts two inoculations, with an inoculation amount of 0.15% high rare earth inoculant and 0.35% barium silicon inoculant. The high-strength and toughness vermicular graphite cast iron scroll disk process of the invention not only has good appearance roughness, but also ensures the finished product effect of the casting. At the same time, the hot riser process is adopted to save costs while achieving the effect of shrinkage compensation. The creeping method adopts wire feeding cored wire, and the inoculation process adopts two inoculations, with the inoculation amount of 0.15% high rare earth inoculant and 0.35% barium silicon inoculant. However, the patent adopts side riser water entry, which has a high risk of sand flushing, many defects in the casting, and severe shrinkage, resulting in poor wear resistance and mechanical properties of the disc casting. Summary of the invention

[0006] 1. Problem to be solved

[0007] Aiming at the problem that the existing casting process for disc castings has many defects and serious shrinkage, the first object of the present invention is to provide a casting process for disc castings, which adopts a horizontal top riser process to reduce the risk of sand blasting, thereby reducing the defects and shrinkage of the castings;

[0008] The second object of the present invention is to provide a pouring system that can be used in the above pouring process to reduce internal defects and shrinkage of castings;

[0009] The third object of the present invention is to provide a disc-like casting made by using the above-mentioned pouring process and pouring system, wherein the disc-like casting has higher mechanical properties and hardness, and the internal shrinkage area meets the use requirements.

[0010] 2. Technical solution

[0011] In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0012] The casting process of general disc castings usually sets a shrinkage compensation riser at the hot node position, but the disc hot node is located in the middle of the shaft hole, that is, the hot node is located in the thick center, which leads to serious shrinkage at the hot node of the disc casting, especially for the disc end face that frequently contacts and collides with other parts. Shrinkage seriously affects the mechanical properties and wear resistance of the disc end face and affects the service life. Therefore, this application uses a horizontal process distribution method according to the hot node position for the structure of the disc casting, and uses a top riser to compensate for the shrinkage at the hot node, which solves the shrinkage and shrinkage cavity problems inside the casting. Disc castings are prone to shrinkage and shrinkage defects.

[0013] This paper mainly conducts material tests on disk castings, so that the creep rate of the disk end surface in the casting is ≥60%, the creep rate of the central thin wall is ≥40%, and the mechanical properties meet the requirements of tensile strength ≥450Mpa, yield strength ≥315MPa, hardness >85HRB, and heat transfer coefficient 40-60W / m·K.

[0014] The first object of the present invention is to provide a vermicular iron material, which controls the magnesium content of molten iron components to ensure that the friction material can work stably under different working conditions.

[0015] Specifically, the vermicular iron material includes components and mass fractions of: C: 3.50%-3.80%, Si: 2.0%-2.60%, Mn: 0.20%±0.50%, Mg: 0.011%-0.020%, S<0.02%, P<0.05%, the alloy element Cu is controlled within 0.3%, and Sn is controlled within 0.055%.

[0016] The second object of the present invention is to provide a process for casting a plate-type casting using the above-mentioned vermicular iron material, which comprises the steps of:

[0017] a) Before smelting, alloy elements and chemical elements in front of the furnace are put into the smelting furnace, and then pig iron, scrap steel and recycled materials are mixed according to the proportion and smelted into molten iron through the smelting furnace. When the molten iron meets the requirements, the molten iron is transferred to the wire feeding station through the tundish;

[0018] b) The molten iron is vermifuged and inoculated at the wire feeding station. After the wire feeding is completed, the molten iron is poured. The pouring temperature is controlled at The molten iron pouring time is controlled within 10 minutes;

[0019] c) Place the molten iron ingate and top riser into the cavity to form a casting;

[0020] d) After pouring, cool on the cooling line for more than 110 minutes before unpacking.

[0021] During the pouring process, the pouring temperature is controlled at 1410-1430°C, and the pouring time of a single bag of molten iron is controlled within 10 minutes to prevent the pouring time from being too long, the molten iron in the pouring machine from creeping, and the inoculation decay. The inoculation process adopts a one-time inoculation, a single inoculation in the creeping bag, and a high rare earth inoculant with an inoculation amount of 0.20%.

[0022] During the smelting process, a medium frequency induction furnace is used with a smelting temperature of 1500-1550°C. The product brand is RT450. The chemical elements before the furnace are: C: 3.50%-3.80%, Si: 2.0%-2.60%, Mn: 0.15%-0.25%, Mg: 0.011%-0.020%, S <0.02%, P <0.05%, the alloy element Cu is controlled within 0.3%, and Sn is controlled within 0.055%. The mechanical properties of the casting are controlled by the alloy elements.

[0023] The molten iron is transferred to the wire feeding station through the tundish (500kg). The creeping method adopted by our company is the cored wire feeding method. The wire feeding temperature is 1450-1470℃, the wire feeding meter is 6m, the wire feeding speed is 21m / min, and the molten iron is poured after the wire feeding is completed.

[0024] Preferably, the high rare earth inoculant includes Si65%-75%, Al0.5%-1.5%, Ca0.5%-1.5%, Ce1%-2.5%, and the rest is Fe and inevitable impurities. No inoculant is added during the casting process. For vermicular iron materials, strengthening the inoculation will increase the number of graphite balls and reduce the creep rate. Therefore, in the production of vermicular iron, it is not advisable to arbitrarily increase the inoculation amount or increase the number of inoculations.

[0025] The obtained vermicular iron material has the following components: C: 3.50%-3.80%, Si: 2.0%-2.60%, Mn: 0.15%-0.25%, Mg: 0.011%-0.020%, S<0.02%, P<0.05%, alloy element Cu is controlled within 0.3%, Sn is controlled within 0.055%, and the rest is Fe and unavoidable impurities.

[0026] The prepared vermicular iron material includes more than 60% of vermicular graphite, and the rest is flake graphite and spherical graphite, wherein the vermicular graphite is a transitional form of graphite between flake graphite and spherical graphite. By controlling graphites with different structures, on the one hand, the creep rate and mechanical properties of the vermicular iron are regulated so that its mechanical properties meet the requirements of tensile strength ≥450Mpa, yield strength ≥315MPa, and hardness >85HRB, and on the other hand, the thermal conductivity of the vermicular iron material is improved so that its thermal conductivity meets the requirements of 40-60W / m·K.

[0027] The carbon equivalent of vermicular iron in this application is high, and rare earth alloys are added to the inoculant to purify the molten iron, which effectively improves the fluidity of the liquid vermicular iron material. Among them, the magnesium element in the furnace affects the creep rate of the material, so the magnesium element must be strictly controlled at 0.011%-0.020%. If the magnesium content is too low, gray iron graphite is likely to appear in the material. Compared with vermicular iron, the strength, plasticity and toughness of gray cast iron are relatively low, resulting in a sudden drop in the mechanical properties of the castings, but too high a magnesium content will lead to a low creep rate of the material, which in turn affects the mechanical properties and thermal conductivity of the material. Therefore, this application controls the magnesium content in the furnace to be 0.011%-0.020%.

[0028] The creep rate of vermicular graphite cast iron has an important influence on the performance of castings. On the one hand, the creep rate affects the mechanical properties of the material: as the creep rate increases, the precipitation morphology of graphite changes. The higher the creep rate, the more vermicular graphite there is in the organization, and the less spherical graphite. The reduction of spherical and flocculent graphite improves the tensile strength, yield strength and hardness of vermicular graphite cast iron. The tensile strength and yield strength are related to the metallographic structure. Generally speaking, the more pearlite content, the greater the strength of the casting; the hardness is positively correlated with the creep rate. The present application controls the creep rate of the disk end face to be ≥60% and the creep rate of the central thin wall to be ≥40%, so that the disk end face with more contact friction has a higher hardness, and its hardness is >85HRB.

[0029] On the other hand, the creep rate has a great influence on the thermal conductivity of the casting. As the creep rate increases, its thermal conductivity gradually increases. Through the study of the three-dimensional graphite morphology in vermicular cast iron, it is believed that the higher the creep rate, the more obvious the networking characteristics of graphite. This possible spatial network structure is conducive to the thermal conductivity of vermicular iron. It is worth noting that the end face of the disk generates heat during the friction process. Traditional castings may have problems with poor thermal stability due to high temperatures. This application improves the thermal conductivity of vermicular iron materials so that its heat transfer coefficient reaches 40-60W / m·K, transfers heat in time, and improves the thermal stability of castings.

[0030] Furthermore, the difference in creep rate between the thin wall of the disk end face and the outer cylindrical surface should not be too large, otherwise the disk end face and the outer cylindrical surface may break. Preferably, the creep rate of the thin wall of the disk end face and the outer cylindrical surface is not more than 20%. During the pouring process, the pouring liquid that first enters the pouring system has a longer cooling time, resulting in uneven temperatures in various parts of the pouring system, affecting the structural consistency of the casting, and further affecting the performance of the casting. Therefore, the present application further improves the temperature uniformity through the pouring system and pouring process parameters, thereby obtaining a casting product with a more uniform tissue distribution.

[0031] A system for implementing the above-mentioned pouring process includes a pouring cup, the bottom of the pouring cup is connected to the straight runner, the bottom of the straight runner is connected to the pouring seat, the straight runner is connected to the pouring seat, the pouring seat is provided with a pouring overlap in the circumference, the pouring seat is connected to the pouring overlap, and the pouring overlap is connected to the top of the riser.

[0032] Although vermicular cast iron has a smaller tendency to shrink than ductile iron, shrinkage and shrinkage defects are prone to occur due to the hot section of the disc casting being located at the thick center. And the tensile test bar of the casting is a body sample, and it is necessary to ensure that the test bar can meet the parameters required by the customer. Therefore, it is impossible to use conventional side risers for shrinkage compensation, so the present invention adopts a horizontal top riser process, which has a large shrinkage compensation pressure and a good shrinkage compensation effect, and has a higher fault tolerance rate during the production process, and can ensure that the casting is dense and free of shrinkage, shrinkage defects such as shrinkage. The position of the riser affects the performance of the casting. If the riser is on the side, the molten iron entering the pouring system has the risk of sand blasting, especially at the hot section of the disc casting, shrinkage and shrinkage defects are prone to occur.

[0033] like Figure 2 The figure shows the process design of the vermicular iron scroll disk. The molten iron enters the casting cavity through the pouring cup and the top riser. This process has no risk of sand blasting, and the top riser process has a good shrinkage compensation effect. The interior of the casting is dense and has no shrinkage. The mechanical properties test meets customer needs.

[0034] The design of the pouring system directly affects the quality of the castings. About 30% of the rejects are caused by unreasonable pouring system design. The pouring system design of the present invention needs to meet the following requirements:

[0035] 1) This paper uses the top riser for shrinkage compensation, combined with the design of the parameters of the pouring cup and riser of the pouring system, which can effectively eliminate the hot node of the casting and obtain a casting with dense interior.

[0036] 2) During the filling process, the molten metal should flow smoothly to avoid turbulence in the flow process. At the same time, it is necessary to prevent the molten metal from being drawn into the gas, causing oxidation or generating pores.

[0037] 3) When the molten metal enters the mold cavity from the inner gate, the tangential velocity during inflow cannot be too large, otherwise it will cause splashing, scouring the inner wall of the mold cavity and the sand core, and ultimately cause poor appearance of the casting.

[0038] 4) The pouring system should not be too large, which will easily lead to low product yield and high production cost. At the same time, the cavity needs to be filled within the specified time, which can improve the production cycle on the one hand and avoid defects such as sand inclusion scarring and cold shut due to the slow rise of the metal liquid level on the other hand.

[0039] 5) The shape of the pouring system is simple and easy to make, and the volume of the sand box is minimized to prevent the sand box from cracking and deforming during the pouring process.

[0040] By controlling the tangential speed of the molten iron filling the mold at each point during the pouring process to less than 1.2m, the risk of sand flushing is reduced. In particular, the tangential speed of the molten iron entering each cavity is less than 0.6m / s, which reduces the defects in the middle hot spot of the disc casting.

[0041] The end surface of the disk contains ≥60% pearlite in the casting, and the rest is ferrite. The creep rate of the disk end surface is ≥60%, the creep rate of the center thin wall is ≥40%, and the mechanical properties meet the requirements of tensile strength ≥450Mpa, yield strength ≥315MPa, hardness>85HRB, and heat transfer coefficient 40-60W / m·K. The internal casting defect standard is in accordance with ASTM-E446: there are no defects in the metallographic and tensile sampling areas, and the defect level of other parts does not exceed level 2. Effectively reduce shrinkage, X-ray flaw detection standard every 2500mm 2 The area allows shrinkage ≤ 100mm 2 .

[0042] 3. Beneficial effects

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The casting process of a disc casting of the present invention adopts a horizontal top riser process, the top riser has a large shrinkage compensation pressure and a good shrinkage compensation effect, has a higher fault tolerance rate in the production process, and the casting is dense inside without shrinkage defects such as porosity and shrinkage cavities;

[0045] (2) A pouring system for a disc-type casting of the present invention designs the parameters of the gate and the feeding riser according to the feeding standard, effectively controls the filling speed of the molten metal, and reduces the internal defects of the casting;

[0046] (3) The disk castings produced by the present invention have a tensile strength of ≥450 MPa, a yield strength of ≥315 MPa, a hardness of >85 HRB, a creep rate of the disk end surface of ≥60%, and a creep rate of the central thin wall of ≥40%, and have high mechanical properties and hardness. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments, but it should be understood that these drawings are designed only for explanation purposes and are not intended to limit the scope of the present invention. In addition, unless otherwise specified, these drawings are intended only to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

[0048] Figure 1 The gating system structure diagram of the present invention includes: 1. pouring cup; 2. sprue; 3. pouring seat; 4. pouring channel overlap; 5. riser;

[0049] Figure 2 This is the microstructure diagram of the casting of Example 1;

[0050] Figure 3 This is a simulation diagram of the filling tangential velocity of the embodiment;

[0051] Figure 4 It is the gating system structure diagram of comparative example 1;

[0052] Figure 5 This is the structural diagram of the pouring system for Comparative Example 2. DETAILED DESCRIPTION

[0053] The following detailed description of exemplary embodiments of the present invention refers to the accompanying drawings, which form a part of the description, and in which exemplary embodiments of the present invention that can be implemented are shown as examples. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement the present invention, it should be understood that other embodiments can be implemented and various changes can be made to the present invention without departing from the spirit and scope of the present invention. The following more detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but is only for the purpose of illustrating and not limiting the description of the characteristics and features of the present invention, so as to propose the best mode for performing the present invention and to enable those skilled in the art to implement the present invention. Therefore, the scope of the present invention is limited only by the appended claims.

[0054] It should be understood that the following text is only used to describe one or several specific embodiments of the present invention, and does not strictly limit the scope of protection of the specific claims of the present invention. As used herein, the terms "parallel" and "perpendicular" are not limited to their strict geometric definitions, but include tolerances for reasonable and inconsistent machining or human errors.

[0055] The high rare earth inoculant in the embodiment includes Si 70%, Al 1%, Ca 1%, Ce 1.8%, and the remainder is Fe and inevitable impurities.

[0056] The pouring system of the present invention, such as Figure 1 As shown, it includes a pouring cup 1, the pouring cup 1 is connected to the sprue 2 below, the bottom of the sprue 2 is connected to the sprue seat 3, the sprue 2 is connected to the sprue seat 3, the sprue seat 3 is provided with a sprue overlap 4 in the circumference, the sprue seat 3 is connected to the sprue overlap 4, and the sprue overlap 4 is connected to the top of the riser 6. The size of the riser is φ72*67mm, and the size of the riser neck is The size of the sprue 2 is 30*5mm.

[0057] The parameters of the sprue 2 and riser 5 are determined according to the solidification principle of the casting. The feeding standard must meet the standards of modulus, volume, pressure and feeding neck. The feeding neck must be large enough, and the modulus standard meets:

[0058] M F =kM ×M C

[0059] Where M F is the modulus of the feeding port, that is, the height of the feeding port;

[0060] M c is the casting modulus, in cm,

[0061]

[0062] Where M c is the casting modulus, V is the volume of the casting, S is the surface area of ​​the casting, and the casting modulus M is obtained by calculating the volume and surface area of ​​the present application. c Take a turbine disk of 0.64 cm as an example.

[0063] k M is a constant, which depends on the thermal conditions of the casting process and the casting characteristics of different alloys. This application comprehensively considers the working conditions, raw materials and casting process, and sets k M The value of is set to 0.7-1.1, and the calculated modulus of the shrinkage-feeding port is the minimum value. In the actual design process, it is usually necessary to meet the following requirements:

[0064] M F ≥k M ×M C

[0065] According to k M The value of is set to 0.7-1.0, when the maximum value is 1.0, then M F The value of M F ≥0.64cm, according to the DISAMATIC 2013LP / PLC-A Sand Molding System Application Manual, when M F When it is 0.64cm, take M F The corresponding diameter when it is 0.66cm is 35mm.

[0066] Riser neck modulus M N satisfy:

[0067] M N ≥M F / 3=0.213

[0068] For a square riser neck with a module of D / 4, the riser neck diameter is:

[0069] D / 4≥0.213cm

[0070] Then, D≥0.852cm, that is, the minimum diameter of the riser neck is 0.832cm.

[0071] By controlling the tangential speed of the molten iron filling the mold at each point during the casting process to less than 1.2m, the risk of sand flushing is reduced. In particular, the tangential speed of the molten iron entering each cavity is less than 0.6m / s, which reduces the defects in the middle hot spot of the disc casting. Figure 3 As shown, the tangential velocities of the molten iron entering each cavity are 0.540m / s, 0.555m / s, 0.553m / s, and 0.518m / s, respectively.

[0072] Example 1

[0073] The raw materials of the CMI material include 5% pig iron, 50% scrap steel and 45% recycled materials by mass fraction. The CMI material includes C: 3.81%, Si: 2.26%, Mn: 0.33%, Mg: 0.015%, S < 0.015%, P < 0.03%, Cu 0.28%, Sn 0.053%. During the smelting process, a medium frequency induction furnace is used, and the smelting temperature is 1550°C.

[0074] The molten iron is transferred to the wire feeding station through the tundish (500kg). The creeping method adopted by our company is the cored wire feeding method. The wire feeding temperature is 1460℃, the wire feeding length is 6m, the wire feeding speed is 21m / min, and the molten iron is poured after the wire feeding is completed.

[0075] The casting process of the scroll disk is obtained by using the above-mentioned vermicular iron material, wherein the casting temperature is controlled at 1422°C, and the casting time of a single bag of molten iron is controlled within 10 minutes to prevent the casting time from being too long, the molten iron in the casting machine from creeping, and the inoculation decay. The inoculation process adopts a one-time inoculation, and a high rare earth inoculant is added with an inoculation amount of 0.20%.

[0076] The obtained vermicular iron material has a creep rate of 65%, contains 60% pearlite, has a tensile strength of 466 MPa, a yield strength of 465.8 MPa, and a hardness of 87.6 HRB. Its microstructure is as follows: Figure 2 As shown, the internal casting defect standard is in accordance with ASTM-E446: metallographic and tensile sampling areas have no defects, and the defect level of other parts does not exceed level 2. Effectively reduce shrinkage, X-ray flaw detection standard every 2500mm 2 The area allows shrinkage ≤ 100mm 2 , the casting of Example 1 is 2500mm 2 The shrinkage area is 48mm 2 .

[0077] Example 2

[0078] The pouring system of Example 2 is the same as that of Example 1, except that the vermicular iron material includes C: 3.81%, Si: 2.26%, Mn: 0.35%, Mg: 0.018%, S 0.017%, P 0.02%, Cu 0.25%, and Sn 0.05%. During the smelting process, a medium frequency induction furnace is used, and the smelting temperature is 1550°C.

[0079] The molten iron is transferred to the wire feeding station through the tundish (500kg). The creeping method adopted by our company is the cored wire feeding method. The wire feeding temperature is 1460℃, the wire feeding length is 6m, the wire feeding speed is 21m / min, and the molten iron is poured after the wire feeding is completed.

[0080] The casting process of the scroll disk is obtained by using the above-mentioned vermicular iron material, wherein the casting temperature is controlled at 1417°C, and the casting time of a single bag of molten iron is controlled within 10 minutes to prevent the casting time from being too long, the molten iron in the casting machine from creeping, and the inoculation decay. The inoculation process adopts a one-time inoculation, and a high rare earth inoculant is added with an inoculation amount of 0.20%.

[0081] The obtained vermicular iron material has a creep rate of 65%, contains 60% pearlite, has a tensile strength of 478Mpa, a yield strength of 477.6MPa, and a hardness of 89.7HRB. The internal casting defect standard is in accordance with ASTM-E446: metallographic and tensile sampling areas have no defects, and the defect level of other parts does not exceed level 2. Effectively reduce shrinkage, X-ray flaw detection standard every 2500mm 2 The area allows shrinkage ≤ 100mm 2 , the casting of Example 2 is 2500mm 2 The shrinkage area is 46mm 2 .

[0082] Example 3

[0083] The pouring system of Example 3 is the same as that of Example 1, except that the vermicular iron material includes C: 3.78%, Si: 2.24%, Mn: 0.34%, Mg: 0.016%, S 0.016%, P 0.02%, Cu 0.26%, and Sn 0.048%. During the smelting process, a medium frequency induction furnace is used, and the smelting temperature is 1550°C.

[0084] The molten iron is transferred to the wire feeding station through the tundish (500kg). The creeping method adopted by our company is the cored wire feeding method. The wire feeding temperature is 1460℃, the wire feeding length is 6m, the wire feeding speed is 21m / min, and the molten iron is poured after the wire feeding is completed.

[0085] The casting process of the scroll disk is obtained by using the above-mentioned vermicular iron material, wherein the casting temperature is controlled at 1426°C, and the casting time of a single bag of molten iron is controlled within 10 minutes to prevent the casting time from being too long, the molten iron in the casting machine from creeping, and the inoculation decay. The inoculation process adopts a one-time inoculation, and a high rare earth inoculant is added with an inoculation amount of 0.20%.

[0086] The obtained vermicular iron material has a creep rate of 65%, contains 60% pearlite, has a tensile strength of 469Mpa, a yield strength of 468.8MPa, and a hardness of 91.3HRB. The internal casting defect standard is in accordance with ASTM-E446: metallographic and tensile sampling areas have no defects, and the defect level of other parts does not exceed level 2. Effectively reduce shrinkage, X-ray flaw detection standard every 2500mm 2 The area allows shrinkage ≤ 100mm 2 , the casting of Example 3 is 2500mm 2 The shrinkage area is 52mm 2 .

[0087] Comparative Example 1

[0088] The vermicular iron material of Comparative Example 1 is the same as that of Example 1, except that the casting process adopts the side riser process for casting, water is poured into both sides, and in the casting system, the runner is connected to the side of the riser, such as Figure 4 shown.

[0089] The obtained casting has a creep rate of 50%, a tensile strength of 396.8Mpa, and a yield strength of 396.6Mpa. Due to the shrinkage inside the casting, the casting of comparative example 1 has a 2 Regional shrinkage> 100mm 2 , the mechanical properties cannot meet the production requirements.

[0090] Comparative Example 2

[0091] The vermicular iron material of Comparative Example 2 is the same as that of Example 1, except that the casting process adopts the side riser process for casting, water is poured into the center, and in the casting system, the runner is connected to the side of the riser, such as Figure 5 shown.

[0092] The obtained casting has a creep rate of 60%, a tensile strength of 345.1 MPa, a yield strength of 344.9 MPa, and shrinkage inside the casting. The casting of comparative example 1 has a thickness of 2500 mm. 2 Regional shrinkage> 100mm 2 , the mechanical properties cannot meet the production requirements.

[0093] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope involved in the present application is not limited to the technical solution formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept, such as a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

[0094] Except for the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described here in detail.

Claims

1. A casting process for a disc casting, characterized in that: By adopting the horizontal top riser process, molten iron containing vermicular iron material enters the mold cavity through the pouring cup (1) and the top of the riser (5), the pouring temperature is 1410-1430°C, and the pouring time of a single bag of molten iron is controlled within 10 minutes.

2. The pouring process according to claim 1, characterized in that: During the pouring process, the tangential speed of molten iron filling the mold is less than 1.2m / s.

3. The pouring process according to claim 2, characterized in that: The vermicular iron material includes: C: 3.63%, Si 2.26%, Mn 0.36%, P 0.03%, S 0.012%, Mg 0.014%, Cu 0.42%, Sn 0.058%, and the rest is Fe and inevitable impurities.

4. The pouring process according to claim 3, characterized in that: The molten iron is subjected to creeping and inoculation. During the inoculation process, one-time inoculation is adopted and an inoculating agent with an inoculating amount of 0.20% is added. The inoculating agent is a high rare earth inoculant.

5. The pouring process according to claim 4, characterized in that: The cored wire feeding method is adopted in the creeping and inoculation process, the wire feeding temperature is 1450-1470℃, the wire feeding meter is 6m, and the wire feeding speed is 21m / min.

6. A pouring system for implementing the pouring process according to any one of claims 1 to 5, characterized in that: The invention comprises a pouring cup (1), wherein the pouring cup (1) is connected to a sprue (2) at its bottom, the bottom of the sprue (2) is connected to a sprue seat (3), the sprue (2) is connected to the sprue seat (3), a sprue overlap (4) is provided in the circumferential direction of the sprue seat (3), the sprue seat (3) is connected to the sprue overlap (4), and the sprue overlap (4) is connected to the top of a riser (5).

7. A disc casting made by the pouring process according to any one of claims 1 to 5, characterized in that: The mechanical properties of the obtained castings meet the following requirements: tensile strength ≥450Mpa, yield strength ≥315MPa; hardness >85HRB.

8. The disc casting according to claim 7, characterized in that: The heat transfer coefficient of the casting is 40-60 W / m·K.

9. The disc casting according to claim 8, characterized in that: The disc end surface creep rate of the disc casting is ≥60%, and the center thin wall creep rate is ≥40%.

10. The disc casting according to claim 9, characterized in that: The disk end surface contains ≥60% pearlite, and the rest is ferrite.

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