Reconstruction steel ingot, preparation method thereof and supporting base

Abstract

The invention relates to a reconstructed steel ingot, a preparation method thereof and a supporting base, and belongs to the technical field of molten steel ingot casting. The preparation method of the reconstructed steel ingot comprises the steps that a pouring base plate is placed on the horizontal ground, then a supporting base is placed in the center of the pouring base plate, a mandrel is placed on the supporting base, and then a steel ingot mold is placed on the pouring base plate; the outer melt is poured into the steel ingot mold, and the pouring speed of the outer melt is 2 t / min to 8 t / min; the supporting base comprises a transverse plate, a thin plate and a plurality of vertical plates, the transverse plate and the thin plate are arranged in parallel, the transverse plate is located above the thin plate, the transverse plate and the thin plate are fixedly connected to the vertical plates, and the vertical plates are evenly distributed along the peripheral face of the transverse plate. The central spindle in the reconstructed steel ingot and the outer melt are metallurgically bonded, cracking is not generated in the forging process, and the defects of element segregation, loosening and shrinkage cavities, non-metallic inclusion aggregation and the like in the steel ingot are relieved.

Description

Technical Field

[0001] The invention relates to the technical field of molten steel ingot casting, and in particular to a reconstructed steel ingot and a preparation method thereof, and a mandrel support base. Background Art

[0002] Forgings are the foundation for the development of industries such as electricity, shipbuilding, metallurgy and machinery, and are the prerequisite for advanced equipment manufacturing. Generally, forgings are made by free forging of steel ingots. With the continuous progress of industry, forgings are constantly developing in the direction of larger sizes, and the specifications of steel ingots for forgings are gradually increasing.

[0003] However, as the size of steel ingots increases, defects such as element segregation, loose shrinkage cavities and aggregation of non-metallic inclusions in the steel ingots become more prominent and are mainly concentrated in the core of the steel ingot, resulting in a significant decrease in the qualified rate of forgings, causing waste of materials, energy, etc. and an increase in production costs.

[0004] In order to alleviate the defects of element segregation, loose shrinkage cavities and non-metallic inclusion aggregation in steel ingots, the prefabricated mandrel is currently mainly used, and then the mandrel is wrapped with a high-temperature external melt to produce a reconstructed steel ingot. However, the obtained reconstructed steel ingot cracks during the forging process due to incomplete solid-liquid fusion or severe interface oxidation, resulting in the scrapping of the reconstructed steel ingot and a waste of resources.

[0005] Therefore, there is an urgent need for a preparation method to ensure that the core shaft in the reconstructed steel ingot is metallurgically bonded with the external melt and that no cracking occurs during the forging process. Summary of the invention

[0006] In view of the above analysis, the present invention aims to provide a reconstructed steel ingot and a preparation method thereof, a support base, to improve the bonding strength between the core shaft and the external melt in the reconstructed steel ingot, and to prevent cracking during the forging process.

[0007] In one aspect, the present invention provides a method for preparing a reconstructed steel ingot, wherein the reconstructed steel ingot comprises a mandrel and an outer melt completely enveloping the mandrel, comprising the following steps:

[0008] S1: Assembly of metallurgical auxiliary tools: Place a casting chassis on a horizontal ground, then place a support base at the center of the casting chassis, place a mandrel on the support base, and then place the ingot mold on the casting chassis;

[0009] S2: external melt pouring: pouring the external melt into the ingot mold, the pouring speed of the external melt is 2-8 t / min;

[0010] The support base includes a horizontal plate, a thin plate and a plurality of vertical plates. The horizontal plate is arranged parallel to the thin plate and is located above the thin plate. The horizontal plate and the thin plate are respectively fixed to the vertical plates, and the plurality of vertical plates are evenly distributed along the outer peripheral surface of the horizontal plate.

[0011] Furthermore, the core shaft and the outer melt are made of the same or different materials.

[0012] Furthermore, the external melt is poured by top pouring or bottom pouring.

[0013] Furthermore, when the external melt is poured by top pouring, the metallurgical auxiliary tool assembly further includes a steel flow collecting sleeve placed on the core shaft, and the steel flow collecting sleeve is located on a side of the core shaft away from the supporting base.

[0014] Furthermore, when the external melt is poured from above, the pouring vacuum is below 67Pa.

[0015] Furthermore, the thickness of the vertical plate and the horizontal plate is 20-80 mm; the thickness of the thin plate is 3-8 mm.

[0016] Furthermore, a plurality of through holes are provided on the vertical plate, the horizontal plate and the thin plate.

[0017] In a second aspect, the present invention provides a reconstructed steel ingot prepared by the preparation method of the present invention.

[0018] Furthermore, the reconstructed steel ingot comprises a mandrel, which accounts for 20%-50% of the weight of the steel ingot and 30%-60% of the cross-section.

[0019] In the third aspect, the present invention provides a support base for implementing the preparation method described in the present invention, wherein the support base includes a horizontal plate, a thin plate and multiple vertical plates, the horizontal plate is arranged parallel to the thin plate, and the horizontal plate is located above the thin plate, the horizontal plate and the thin plate are respectively fixed to the vertical plates, and the multiple vertical plates are evenly distributed along the outer peripheral surface of the horizontal plate.

[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0021] 1. The reconstructed steel ingot of the present invention includes a mandrel and an external melt. During the preparation process, a support base is used to support the mandrel, and the pouring method and pouring speed of the external melt are controlled, thereby improving the bonding strength between the mandrel and the external melt, and ensuring that the reconstructed steel ingot does not crack during the forging process. The defects of element segregation, loose shrinkage cavities, and non-metallic inclusion aggregation in the prepared reconstructed steel ingot are improved.

[0022] 2. The support base provided by the present invention includes a horizontal plate, a thin plate and a plurality of vertical plates, wherein the horizontal plate is arranged in parallel with the thin plate, the horizontal plate and the thin plate are respectively fixed to the vertical plate, and the plurality of vertical plates are evenly distributed along the outer peripheral surface of the horizontal plate. On the one hand, the support base supports the mandrel, and on the other hand, through the structural design of the support base, the solid-liquid fusion effect and the interface bonding strength are improved, the tearing along the interface during the forging process is prevented, and the oxidation caused by contact with air at high temperature is reduced, resulting in a large amount of oxide inclusions wrapped in the forging, thereby reducing the quality of the forging, and even directly causing the forging to be scrapped during forging.

[0023] 3. In the present invention, the materials of the core shaft and the outer melt can be homogeneous or heterogeneous. When the materials of the core shaft and the outer melt are heterogeneous, the core shaft can be made of a material that is slightly inferior in price and performance to the outer melt, which greatly saves production costs.

[0024] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0026] Figure 1 This is a schematic diagram of metallurgical auxiliary tool assembly;

[0027] Figure 2 is a schematic diagram of the mandrel;

[0028] Figure 3 It is a schematic diagram of the cross-axial section of the steel flow collecting sleeve;

[0029] Figure 4 This is a schematic diagram of the support base;

[0030] Figure 5 It is a schematic diagram of a circular horizontal plate;

[0031] Figure 6 It is a schematic diagram of a fan-shaped horizontal plate;

[0032] Figure 7 It is a schematic diagram of a combined fan-shaped horizontal plate;

[0033] Figure 8 It is a schematic diagram of the vertical plate;

[0034] Fig. 9 It is a schematic diagram of a vertical plate with a card slot;

[0035] Fig.10 It is a schematic diagram of a fan-shaped thin block;

[0036] Fig.11 This is the crack defect of the reconstructed steel ingot after forging obtained in Comparative Example 1;

[0037] Fig.12a This is the core shaft hanging and hoisting scheme of comparative example 2;

[0038] Figure 12b This is a schematic diagram of the suspended lifting scheme of the mandrel of comparative example 2;

[0039] In the figure, 1. pouring chassis; 2. ingot mold; 3. insulation riser; 4. support base; 41. horizontal plate; 42. vertical plate; 43. thin plate; 44. positioning block; 45. upper groove; 46. lower groove; 47. slot; 5. core shaft; 6. steel flow collecting sleeve; 7. first through hole; 71. second through hole; 72. third through hole; 73. fourth through hole; 81. first block; 82. second block; 83. third block. DETAILED DESCRIPTION

[0040] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0041] With the development of industry, forgings and steel ingots for forgings have also become larger in size. The heavier the ingot, the more prominent its internal element segregation, loose shrinkage cavities and non-metallic inclusion aggregation defects, especially in the core of the ingot.

[0042] In order to improve the defects in the core of the steel ingot, a research direction of reconstructed steel ingots is proposed, in which a mandrel is prefabricated and then the prefabricated mandrel is wrapped with a high-temperature external melt. However, the obtained reconstructed steel ingot has a cracking problem during the forging process. Therefore, the present invention provides a method for preparing a reconstructed steel ingot, comprising the following steps:

[0043] S1: Assembly of metallurgical auxiliary tools: Place a casting chassis on a horizontal ground, then place a support base at the center of the casting chassis, place a mandrel on the support base, and then place the ingot mold on the casting chassis;

[0044] S2: external melt pouring: pouring the external melt into the ingot mold, the pouring speed of the external melt is 2-8 t / min;

[0045] The support base includes a horizontal plate, a thin plate and a plurality of vertical plates. The horizontal plate is arranged parallel to the thin plate and is located above the thin plate. The horizontal plate and the thin plate are respectively fixed to the vertical plates, and the plurality of vertical plates are evenly distributed along the outer peripheral surface of the horizontal plate.

[0046] Compared with the prior art, the present invention adopts a supporting base to support the mandrel and controls the pouring method and pouring speed of the external melt, which can effectively improve defects such as element segregation, loose shrinkage cavities and non-metallic inclusion aggregation in the steel ingot; and through the structural design of the supporting base, the solid-liquid fusion effect and the interface bonding strength are improved, so that the mandrel and the external melt can achieve metallurgical and mechanical bonding, preventing tearing along the interface during the forging process, and reducing a large amount of oxide inclusions wrapped in the forging, thereby ensuring the quality and forgeability of the reconstructed steel ingot.

[0047] Reference Figure 1 and Figure 2 , the preparation of the reconstructed steel ingot comprises the following steps,

[0048] S1: Metallurgical auxiliary tool assembly:

[0049] The pouring chassis 1 is placed on a horizontal ground. The pouring chassis 1 is a cylinder, and a groove is opened at the center of the pouring chassis 1. The cross-section of the groove through the axis is an inverted trapezoid.

[0050] Then, the support base 4 is placed in the groove, wherein the support base 4 comprises a horizontal plate 41, a thin plate 43 and a plurality of vertical plates 42, wherein the horizontal plate 41 is arranged parallel to the thin plate 43 and the horizontal plate 41 is above the thin plate 43, the horizontal plate 41 and the thin plate 43 are respectively fixedly connected to the vertical plates 42, and the plurality of vertical plates 42 are evenly distributed along the outer peripheral surface of the horizontal plate 41;

[0051] The mandrel 5 is then placed on the vertical plate 42 of the support base 4;

[0052] Finally, a steel ingot mold 2 is placed on the pouring chassis 1, and a heat-insulating riser 3 is placed on the steel ingot mold 2, and the assembly of the metallurgical auxiliary tools is completed.

[0053] S2: External melt pouring:

[0054] Smelting of external melt: the refining temperature is controlled at 1580℃-1590℃; when the vacuum degree of the vacuum chamber is lower than 67Pa and the temperature of the melt outside the tundish is measured to be 1550℃-1560℃, pouring is ready; the pouring speed of the external melt is 2-8t / min; after cooling, a reconstructed steel ingot is obtained.

[0055] Specifically, the core shaft 5 and the outer melt are made of the same or different materials.

[0056] The reconstructed steel ingot is composed of a mandrel 5 and an external melt, and the mandrel 5 and the external melt may be made of the same material or different materials. When the mandrel 5 and the external melt are made of different materials, the reconstructed steel ingot can be used to prepare forgings such as support rollers and pipes. The characteristics of support rollers and pipes are that their working parts are mainly on the surface, that is, at the external melt in the reconstructed steel ingot. Therefore, while ensuring the performance of the reconstructed steel ingot, the mandrel 5 can be made of a cheap material with slightly poorer performance, which greatly reduces the production cost.

[0057] Specifically, the external melt is poured by top pouring or bottom pouring.

[0058] The upper pouring of the present invention refers to: molten steel is directly poured into the ingot mold 2 from the top. The lower pouring refers to: molten steel enters the ingot mold 2 from the bottom through the center pouring pipe and the pouring channel. The upper pouring and the lower pouring are commonly used pouring methods in the art, which will not be described here, and the pouring channel is not shown in the figure.

[0059] When the top pouring method is adopted, the pouring speed is 3-8t / min. When the pouring speed is lower than 3t / min, the pouring speed is too low, the temperature gradient of the molten steel (referring to the external melt) increases, affecting the distribution of the final temperature field of the reconstructed ingot, and the increase in internal stress leads to the generation of defects such as cracks; in addition, the molten steel has poor fluidity, which is not conducive to the floating of inclusions and the fusion of the molten steel and the supporting base 4; when the pouring speed is greater than 8t / min, the pouring speed is too high, the degassing effect of the droplets is poor, the impact of the molten steel on the auxiliary tool is large, the liquid level is unstable, which is also not conducive to the floating of inclusions, and it is very easy to cause defects such as loose shrinkage cavities and aggregation of non-metallic inclusions in the reconstructed ingot.

[0060] When the pouring method is adopted, the pouring speed is 2-5t / min. When the pouring speed is lower than 2t / min, the pouring speed is too low, and part of the molten steel condenses into the runner, resulting in the molten steel temperature entering the ingot mold 2 being too low, and the metallurgical bonding between the molten steel and the supporting base 4 cannot be achieved, which leads to cracks in the forging process. In more serious cases, the flow may be interrupted, resulting in the failure of the pouring; when the pouring speed is greater than 5t / min, the pouring speed is too high, and the erosion of the refractory runner by the molten steel is aggravated, resulting in the reduction of the purity of the molten steel. At the same time, the liquid level rises unsteadily, affecting the surface quality of the ingot.

[0061] Specifically, when the external melt is poured from above, the metallurgical auxiliary tool assembly further includes a steel flow collecting sleeve 6 placed on the core shaft 5 , and the steel flow collecting sleeve 6 is located on the side of the core shaft 5 away from the supporting base 4 .

[0062] When the present invention adopts the top pouring method to cast the external melt, a steel flow collecting sleeve 6 is added to the core shaft 5, which can effectively restrain the high-temperature external melt and prevent the splashing of the external melt from causing quality problems such as scarring on the surface of the reconstructed steel ingot.

[0063] Specifically, refer to Figure 3 The steel flow collecting sleeve 6 is cylindrical or truncated cone-shaped. A plurality of overflow holes are provided in the middle of the steel flow collecting sleeve 6 to facilitate the external melt to flow from the steel flow collecting sleeve 6 into the steel ingot mold 2.

[0064] Specifically, the steel flow collecting sleeve 6 can be a welded part or an integrally formed part.

[0065] Specifically, one end of the steel flow collecting sleeve 6 is assembled with the core shaft 5 , and the inner diameter of the steel flow collecting sleeve 6 is the same as the outer diameter of the upper end of the core shaft 5 .

[0066] Specifically, when the external melt is poured from above, the pouring vacuum is below 67 Pa. When pouring the external melt, the gas content needs to be controlled to a lower level to prevent defects such as shrinkage and shrinkage cavities from occurring during the cooling stage. When the vacuum is lower than 67 Pa, the hydrogen in the steel is reduced to below 1 ppm, greatly reducing the risk of white spots and hydrogen-induced cracks in forgings.

[0067] The reconstructed steel ingot comprises a mandrel 5, which accounts for 20%-50% of the weight of the steel ingot and 30%-60% of the cross-section.

[0068] According to the actual production needs, the proportion of the mandrel 5 can be selected. When the mandrel 5 accounts for less than 20% of the weight of the steel ingot, it is impossible to effectively prevent defects such as element segregation, loose shrinkage cavities and non-metallic inclusion aggregation in the steel ingot; when the mandrel 5 accounts for more than 50% of the weight of the steel ingot, the external melt cannot melt the surface of the mandrel 5, and the two cannot achieve metallurgical bonding. As for the cross-sectional proportion, it depends on the function and shape of the forging, and at the same time, it is considered that the external melt must provide enough heat to produce the corresponding metallurgical bonding.

[0069] In order to realize the method for preparing the reconstructed steel ingot of the present invention, a support base 4 is provided to support the mandrel 5. Figure 4 The support base 4 includes a horizontal plate 41, a thin plate 43 and a plurality of vertical plates 42. The horizontal plate 41 is arranged parallel to the thin plate 43, and the horizontal plate 41 is located above the thin plate 43; the horizontal plate 41 and the thin plate 43 are respectively fixed to the vertical plates 42, and the plurality of vertical plates 42 are evenly distributed along the outer peripheral surface of the horizontal plate 41.

[0070] Specifically, the thickness of the vertical plate 42 and the horizontal plate 41 is 20-80 mm; the thickness of the thin plate 43 is 3-8 mm.

[0071] The thickness of the vertical plate 42 and the horizontal plate 41 is 20-80 mm. When the thickness is less than 20 mm, the heat of the external melt is too large, resulting in an increased risk of structural instability of the support base 4, thereby affecting the axis deviation of the mandrel 5 or casting failure; when the thickness is greater than 80 mm, the bottom cooling effect is increased, making the fluidity of the molten steel at the bottom of the ingot worse, and easily forming defects such as loose shrinkage cavities. In addition, the thickness of the thin plate 43 is 3-8 mm.

[0072] The support base 4 bears all the weight of the core shaft 5. The horizontal plate 41 and the vertical plate 42 are the main supporting components of the support base 4. The material of the support base 4 is the same as that of the core shaft 5, or the same as that of the external melt, or the melting point is lower than that of the external melt. The support base 4 can not only support the core shaft 5, but also ensure that a closed forging is formed during the subsequent forging process without causing large cracks. The thin plate 43 mainly plays the role of reinforcing the reinforcement in the support base 4 to prevent the collapse of the support base 4 during use. In addition, when pouring the external melt, the role of the thin plate 43 is mainly to strengthen the fusion of the core shaft 5 and the external melt and improve the metallurgical bonding effect.

[0073] Specifically, a plurality of through holes are provided on the vertical plate 42, the horizontal plate 41 and the thin plate 43. In the present invention, the through hole can be circular or polygonal. During the pouring process, the external melt is convenient for melting the support base 4, so that the external melt, the support base 4 and the core shaft 5 are metallurgically bonded. After the external melt is cooled, the external melt passes through the through hole and wraps the support base 4, so that the external melt and the support base 4 are mechanically bonded.

[0074] Specifically, the support base 4 is integrally formed.

[0075] Specifically, the support base 4 can connect the vertical plate 42 , the horizontal plate 41 and the thin plate 43 by welding.

[0076] Specifically, the horizontal plate 41 is a disk, and a first through hole 7 is opened at the center, and a plurality of second through holes 71 are evenly opened around the first through hole 7. Figure 5 .

[0077] Specifically, the horizontal plate 41 is composed of a plurality of concentric identical fan-shaped blocks, the number of which is equal to the number of the vertical plates 42, and the fan-shaped blocks are provided with second through holes 71, Figure 6 .

[0078] During the manufacturing process, the fan-shaped blocks can be connected by welding the first block 81, the second block 82 and the third block 83, or they can be formed as one piece; then they are fixed to the side wall between the two vertical plates 42 by welding technology, and multiple fan-shaped blocks are located at the same horizontal position.

[0079] Preferably, the sector block is composed of a first block 81, a second block 82 and a third block 83 which are sequentially connected along the radial direction from the center of the circle, and the second block 82 is located between the first block 81 and the third block 83, and the first block 81 and the third block 83 have the same thickness, and the second block 82 has a thickness greater than the first block 81 or the third block 83. Figure 7 .

[0080] Preferably, a second through hole 71 is formed in the second block 82 .

[0081] Preferably, a triangular elongated body is fixedly connected to the third block 83 , and the elongated body is located on a side of the third block 83 away from the second block 82 .

[0082] The external melt wraps the support base 4 and partially melts the horizontal plate 41 and the vertical plate 42, so that the external melt is metallurgically bonded with the horizontal plate 41 and the vertical plate 42. A triangular elongated body is arranged on the third block 83, and the thickness is equal to or slightly less than that of the third block 83, which can promote the fusion of the horizontal plate 41, the vertical plate 42 and the external melt.

[0083] Reference Figure 8 Specifically, the vertical plate 42 is rectangular, and a plurality of third through holes 72 are opened on the vertical plate 42. A positioning block 44 is fixedly connected to the upper end of the vertical plate 42. The positioning block 44 has a certain inclination angle, which is adapted to the lower end of the core shaft 5. The inclined surface of the positioning block 44 and the plane at the bottom of the inclined surface cooperate with the lower end of the core shaft 5 to realize the positioning and support of the core shaft 5 by the support base 4.

[0084] After pouring the external melt, the external melt gradually fills upward from the bottom of the support base 4 until the support base 4 is submerged, and the external melt continues to be poured to gradually submerge the mandrel 5. Since the high-temperature external melt contacts the vertical plate 42 and melts the surface of the vertical plate 42 and the horizontal plate 41, the external melt supports the base 4 to achieve metallurgical bonding; in addition, the external melt enters the cavity of the support base 4 composed of the vertical plate 42, the horizontal plate 41 and the thin plate 43, and the external melt enters the third through hole 72 on the vertical plate 42. After cooling, the external melt and the support base 4 are mechanically bonded. During the forging process, the separation of the external melt and the mandrel 5 is effectively reduced, thereby ensuring the forging quality.

[0085] Preferably, the side wall of the vertical plate 42 is a wave-shaped structure, and an upper groove 45 and a lower groove 46 are formed at the upper and lower ends of the vertical plate 42 .

[0086] The wave-shaped structure, the upper groove 45 and the lower groove 46 are arranged on the vertical plate 42, which increases the contact bonding area between the external melt and the vertical plate 42, further increases the mechanical bonding strength between the external melt and the support base 4, and the external melt wraps the support base 4 and the mandrel 5. During the forging process, when the bonding strength between the support base 4 and the external melt is low, cracks are generated in the support base 4 and the external melt, and the cracks gradually expand from the support base 4 to the direction of the mandrel 5, eventually resulting in separation between the mandrel 5 and the external melt after forging.

[0087] Preferably, a slot 47 is provided on the vertical plate 42, extending toward one side of the wavy structure, and the slot 47 is for the horizontal plate 41 to be inserted. Fig. 9 .

[0088] When the horizontal plate 41 adopts an integrated circular structure (such as Figure 5 As shown), it is necessary to open a slot 47 for the horizontal plate 41 to be inserted on the vertical plate 42, and the vertical plates 42 are inserted into the horizontal plate 41 in sequence along the circumferential direction of the horizontal plate 41, and the vertical plates 42 are evenly distributed.

[0089] Specifically, the thin plate 43 is composed of a plurality of concentric identical fan-shaped thin blocks, the number of the fan-shaped thin blocks is equal to the number of the vertical plates 42, and a fourth through hole 73 is opened on the fan-shaped block. Fig.10 .

[0090] During the manufacturing process, the fan-shaped thin blocks are manufactured separately and then fixed to the side wall between the two vertical plates 42 by welding technology. The multiple fan-shaped thin blocks are located at the same horizontal position and below the horizontal plate 41.

[0091] In order to more clearly describe the present invention, Example 1 (homologous + above note) is further illustrated by the following examples and comparative examples:

[0092] The reconstructed steel ingot of this embodiment is used to prepare the support roll forgings, and its weight is 38.5 tons. The weight of the required reconstructed steel ingot is 62 tons, of which the weight of the mandrel is 17 tons.

[0093] The reconstructed steel ingot includes a core shaft and an outer melt, and the materials of the core shaft and the outer melt are both 45Cr4NiMoV.

[0094] S1: Metallurgical auxiliary tool assembly:

[0095] Place the pouring chassis on a horizontal ground. The pouring chassis is a cylinder, and a groove is opened at the center of the pouring chassis. The cross-section of the groove is an inverted trapezoid.

[0096] Then, the support base is placed in the groove, the support base is 200mm higher than the groove, and the support base includes a horizontal plate, a thin plate and a plurality of vertical plates. The horizontal plate is arranged parallel to the thin plate, the distance between them is 220mm, and the horizontal plate is located above the thin plate. The horizontal plate and the thin plate are respectively fixed to the vertical plate, and the plurality of vertical plates are evenly distributed along the outer circumference of the horizontal plate;

[0097] The vertical plate is a rectangle with a thickness of 60 mm, and is provided with a plurality of third square through holes, each of which has a side length of 50 mm. A positioning block is fixedly connected to the upper end of the vertical plate, and the positioning block has a certain inclination angle, which is adapted to the lower end of the core shaft. The side wall of the vertical plate is a wave-shaped structure, and an upper groove and a lower groove are provided at the upper and lower ends of the vertical plate.

[0098] The transverse plate is composed of a plurality of identical sector-shaped blocks, and has a thickness of 40 mm. A second through hole is opened on the sector-shaped block, and the diameter of the second through hole is 100 mm. The number of the sector-shaped blocks is equal to the number of the vertical plates.

[0099] The thin plate is composed of a plurality of identical fan-shaped thin blocks, and the thickness of the thin plate is 5 mm; and a fourth through hole is opened on the fan-shaped thin block, and the diameter of the fourth through hole is 150 mm. The number of the fan-shaped thin blocks is equal to the number of the vertical plates.

[0100] Then place the mandrel on the vertical plate of the support base, and the lower end of the mandrel is matched with the upper end of the support base; equip the mandrel with a steel flow collection sleeve, and the upper end of the mandrel is matched with the lower end of the steel flow collection sleeve. Finally, place the ingot mold on the casting chassis, and then place the insulation riser on the ingot mold. The assembly of metallurgical auxiliary tools is completed.

[0101] S2: External melt pouring:

[0102] Melting of external melt: the refining steel temperature is controlled at 1580℃-1590℃; when the vacuum degree of the vacuum chamber is lower than 67Pa and the temperature of the melt outside the tundish is measured to be 1550℃-1560℃, pouring is ready; use upper pouring with a pouring speed of 5.5t / min, and obtain reconstructed steel ingot after cooling.

[0103] Example 2 (homogeneous + betting)

[0104] The preparation process of Example 2 is substantially the same as that of Example 1, except that Example 2 adopts downward pouring for casting, the casting speed is 2.5 t / min, and does not contain a steel flow collection sleeve.

[0105] Example 3 (heterogeneous + injection)

[0106] The preparation process of Example 3 is substantially the same as that of Example 1, except that the materials of the core shaft and the external melt in Example 3 are heterogeneous, the material of the core shaft is 42CrMo, and the material of the external melt is 45Cr4NiMoV.

[0107] Example 4 (heterogeneous + betting)

[0108] The preparation process of Example 4 is substantially the same as that of Example 2, except that the materials of the core shaft and the external melt in Example 4 are heterogeneous, the material of the core shaft is 42CrMo, and the material of the external melt is 45Cr4NiMoV.

[0109] Comparative Example 1

[0110] In Comparative Example 1, the supporting base adopts a simple core support, which is a hollow cylinder and has a plurality of grooves at the upper and lower openings of the core support.

[0111] Comparative Example 2

[0112] Comparative Example 2 uses the method of hanging the mandrel in the air without using any supporting base (refer to Fig.12a and 12b ).

[0113] Performance Testing

[0114] The reconstructed steel ingots obtained in the above-mentioned Examples 1-4 and Comparative Examples 1-2 were forged, and the forging process was divided into four fires. The first fire: light upsetting of the ingot bottom; the second fire: pulling the ingot body through the entire length, and pressing the sprue jaws; the third fire: upsetting, KD, and the KD reduction was 20% of the billet height; the fourth fire: pulling and cutting the finished product. The obtained reconstructed steel ingot was observed for cracks, that is, the degree of interface closure, and then annealed after forging to test the mechanical properties of the bonding interface. The sampling position was 100 mm above the lowest point of the mandrel, where the melt and the mandrel were combined. The test results are shown in Table 1.

[0115] Table 1 Test results

[0116] Group Interface closure Tensile strength* / MPa Yield strength* / MPa Example 1 No cracks 598 261 Example 2 No cracks 588 257 Example 3 No cracks 594 273 Example 4 No cracks 583 259 Comparative Example 1 Cracking - - Comparative Example 2 No cracks 578 259

[0117] *“-” in Table 1 means no test was performed

[0118] It can be seen from Examples 1-4 and Comparative Examples 1-2 and Table 1 that in Examples 1-4 of the present invention, under the support of the support base and by controlling the pouring speed and pouring method, the obtained reconstructed steel ingots have no cracks during the forging process, have high bonding strength, and have high coaxiality.

[0119] Reference Fig.11 When the conventional core support was used in Comparative Example 1, the obtained reconstructed steel ingot exhibited severe cracking during the forging process, resulting in the scrapping of the reconstructed steel ingot.

[0120] Reference Fig.12a In comparative example 2, the mandrel is placed in the steel ingot mold by hanging in the air, and there is no support under the mandrel. When pouring the external melt, the external melt squeezes the mandrel, causing the mandrel to deviate, and the reconstructed steel ingot obtained after cooling cannot ensure the coaxiality of the external melt and the mandrel.

[0121] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a reconstructed steel ingot, the reconstructed steel ingot comprising a mandrel and an outer melt completely wrapping the mandrel, characterized in that: The following steps are involved: S1: Assembly of metallurgical auxiliary tools: Place a casting chassis on a horizontal ground, then place a support base at the center of the casting chassis, place a mandrel on the support base, and then place the ingot mold on the casting chassis; S2: external melt pouring: pouring the external melt into the ingot mold, the pouring speed of the external melt is 2-8 t / min; The support base includes a horizontal plate, a thin plate and a plurality of vertical plates. The horizontal plate is arranged parallel to the thin plate and is located above the thin plate. The horizontal plate and the thin plate are respectively fixed to the vertical plates, and the plurality of vertical plates are evenly distributed along the outer peripheral surface of the horizontal plate.

2. The method for preparing the reconstructed steel ingot according to claim 1, characterized in that: The core shaft and the outer melt are made of the same or different materials.

3. The method for preparing the reconstructed steel ingot according to claim 1, characterized in that: The external melt is poured in an upward or downward manner.

4. The method for preparing the reconstructed steel ingot according to claim 3, characterized in that: When the pouring method of the external melt is upper pouring, the metallurgical auxiliary tool assembly also includes a steel flow collecting sleeve placed on the core shaft, and the steel flow collecting sleeve is located on the side of the core shaft away from the supporting base.

5. The method for preparing the reconstructed steel ingot according to claim 3, characterized in that: When the external melt is poured from above, the pouring vacuum is below 67Pa.

6. The method for preparing a reconstructed steel ingot according to claim 1, characterized in that: The thickness of the vertical plate and the horizontal plate is 20-80 mm; the thickness of the thin plate is 3-8 mm.

7. The method for preparing a reconstructed steel ingot according to claim 1, characterized in that: A plurality of through holes are provided on the vertical plate, the horizontal plate and the thin plate.

8. A reconstructed steel ingot, characterized in that: The method is prepared by any one of claims 1 to 7.

9. The method for preparing a reconstructed steel ingot according to claim 8, characterized in that: The reconstructed steel ingot includes a mandrel, which accounts for 20%-50% of the weight of the steel ingot and 30%-60% of the cross-section.

10. A support base for implementing the preparation method according to any one of claims 1 to 7, characterized in that: The support base includes a horizontal plate, a thin plate and a plurality of vertical plates. The horizontal plate is arranged parallel to the thin plate and is located above the thin plate. The horizontal plate and the thin plate are respectively fixed to the vertical plates, and the plurality of vertical plates are evenly distributed along the outer peripheral surface of the horizontal plate.

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