A method of manufacturing an electroslag ingot by smelting and forging

Abstract

The application relates to the technical field of electroslag smelting, and discloses a manufacturing method for electroslag ingot smelting and forging. The method comprises the following steps: in the 0-45min of an electrode melting process, the initial melting speed V1 of the electrode is controlled to be 540kg / h-560kg / h, and the initial flow Q1 of the crystallizer cooling water is controlled to be 280m 3 / h-300m 3 / h; after the electrode melting process lasts for the 45min, the stable melting speed V2 of the electrode is controlled to be 580kg / h-600kg / h, and the stable flow Q2 of the crystallizer cooling water is controlled to be 350m 3 / h-400m 3 / h, until the electroslag ingot is formed; when the electroslag ingot is formed, the electroslag ingot is forged from the middle position of the axial direction to the two ends of the electroslag ingot, until a step in the radial direction of the electroslag ingot is forged on the bottom of the electroslag ingot; the step is cut off along the circumferential direction of the electroslag ingot; and the end of the electroslag ingot is detected, and the defect position determined through the detection is cut off. The application can improve the yield and the quality of the finished product of the electroslag ingot.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electroslag smelting, and particularly to a manufacturing method of electroslag ingot smelting and forging. BACKGROUND

[0002] In the prior art, a large cooling intensity is used in electroslag remelting, which can improve the depth of the metal bath, shorten the local solidification time, refine the grains, reduce the solute atom segregation, and promote the uniform distribution of elements in the electroslag ingot. However, the increase of the cooling intensity will result in poor surface quality of the electroslag ingot, especially the bottom of the electroslag ingot, which often has wrinkle-shaped dents, and during the forging process, the dents become folds and the iron oxide scale is involved, causing forging defects and affecting the product quality of the electroslag ingot. In the traditional forging process, the part with the forging defects is usually cut off as a whole, resulting in a low material yield of the electroslag ingot after forging and a large waste of resources. SUMMARY

[0003] The present application aims to provide a manufacturing method of electroslag ingot smelting and forging, which can improve the product quality and material yield of the electroslag ingot.

[0004] Other characteristics and advantages of the present application will become apparent from the following detailed description, or will be learned by practice of the present application.

[0005] According to one aspect of an embodiment of the present application, a manufacturing method of electroslag ingot smelting and forging is provided, which comprises: controlling the initial melting speed V1 of the electrode to be 540 kg / h-560 kg / h and controlling the initial flow rate Q1 of the crystallizer cooling water to be 280 m 3 / h-300 m 3 / h within 0-45 min of the electrode melting process; controlling the stable melting speed V2 of the electrode to be 580 kg / h-600 kg / h and controlling the stable flow rate Q2 of the crystallizer cooling water to be 350 m 3 / h-400 m 3 / h after the electrode melting process lasts for 45 min, until the electroslag ingot is formed; during the forming forging of the electroslag ingot, forging the electroslag ingot from the middle position of the axial direction to both ends of the electroslag ingot until a step protruding in the radial direction of the electroslag ingot is formed at the bottom of the electroslag ingot; cutting off the step along the circumferential direction of the electroslag ingot; and performing flaw detection on the end of the electroslag ingot and cutting off the defect position determined by the flaw detection.

[0006] In one embodiment of the present application, based on the foregoing scheme, the step protruding in the radial direction of the electroslag ingot is formed by forging the bottom of the electroslag ingot, and the method comprises: if the cross section of the electroslag ingot after forging is circular, controlling the width W1 of the step to be 200×D 2 / D0 2Wherein D is the diameter of the electroslag ingot before forging, D0 is the diameter of the electroslag ingot after forging, the height H1 of the step is controlled to be 0.05D0; if the cross section of the electroslag ingot after forging is a square, the width W2 of the step is controlled to be 50xpiD 2 / L0 2 Wherein D is the diameter of the electroslag ingot before forging, L0 is the side length of the cross section of the electroslag ingot after forging, and the height H2 of the step is controlled to be 0.05L0.

[0007] In an embodiment of the present application, based on the foregoing scheme, before the electroslag ingot is formed by forging, the method further comprises: heating the electroslag ingot, and controlling the heating temperature of the electroslag ingot to be 1150-1300℃, and controlling the heating time of the electroslag ingot to be 15-36h.

[0008] In an embodiment of the present application, based on the foregoing scheme, the flaw detection on the end of the electroslag ingot and the cutting of the defect position determined by the flaw detection, the method comprises: using an ultrasonic detector to detect the end of the electroslag ingot, and cutting the defect position determined by the flaw detection.

[0009] In an embodiment of the present application, based on the foregoing scheme, when the electroslag ingot is formed by forging, the electroslag ingot is forged by using a free forging method.

[0010] In an embodiment of the present application, based on the foregoing scheme, during the melting process of the electrode, 38kg of slag is added for every 1t of electrode, and the mass percentage of CaF2 and Al2O3 in the slag is 7:3.

[0011] In an embodiment of the present application, based on the foregoing scheme, in the electroslag ingot, the sum of the mass of Si, Cr, Ni, Mo, V and Mn accounts for 4.5%-10.5% of the total mass percentage of the electroslag ingot.

[0012] In an embodiment of the present application, based on the foregoing scheme, the diameter of the crystallizer is 540-730mm.

[0013] In an embodiment of the present application, based on the foregoing scheme, the mass of the electroslag ingot is 3-10t.

[0014] In the technical scheme of the embodiment of the present application, the initial melting speed V1 of the electrode is controlled to be 540-560kg / h in the first 45 minutes of the melting of the electrode, at this time, the initial flow rate Q1 of the cooling water of the crystallizer is controlled to be 280-300m 3 / h-300m 3 / h, the cooling intensity of the bottom of the electroslag ingot is properly reduced to reduce the depth of surface defect generation and the internal heat accumulation, and the initial internal solidification of the electroslag ingot is ensured. After the electrode is melted for 45 minutes, the bottom of the electroslag ingot is solidified, at this time, the stable melting speed V2 of the electrode is controlled at 580kg / h-600kg / h, the stable horizontal flow Q2 of the crystallizer is controlled at 350m 3 / h-400m 3 / h, the overall solidification of the electroslag ingot can be improved. After the electroslag ingot is formed, forging is performed from the middle position to both ends in the axial direction, internal defects existing in the bottom can be extruded outward, which is beneficial to improving the material yield. In the final forging forming, the bottom near the material with more surface defects is left with a certain radial size allowance, mechanical processing is performed, surface defects are removed, most of the material without defects is reserved, and at the same time, flaw detection treatment is performed, the part still having defects after the mechanical processing is removed as a whole, which can significantly improve the material utilization and the quality of the finished product.

[0015] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory and are not restrictive of the application. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0017] Figure 1 The flow chart of the electroslag ingot smelting and forging manufacturing method according to the embodiment of the present application is shown.

[0018] Figure 2 The cooling intensity and local solidification time diagram corresponding to each position in the electroslag ingot production process according to the embodiment of the present application is shown.

[0019] Figure 3 The change of the electroslag ingot point position before and after the first deformation of the electroslag ingot and the corresponding equivalent stress diagram according to the embodiment of the present application are shown.

[0020] Figure 4 The equivalent stress distribution diagram of the forged ingot in the first deformation process of the electroslag ingot according to the embodiment of the present application is shown.

[0021] Figure 5 The metal flow velocity distribution diagram of the electroslag ingot in the first deformation process of the electroslag ingot according to the embodiment of the present application is shown.

[0022] Figure 6A schematic diagram of step removal of an electroslag ingot according to the embodiment of the present application. DETAILED DESCRIPTION

[0023] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations may, however, be implemented in many different forms and should not be construed as limited to the examples set forth herein; rather, these example implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of example implementations to those skilled in the art.

[0024] The flow charts shown in the drawings are only illustrative and do not necessarily include all the contents and operations / steps, nor are they necessarily executed in the order described. For example, some operations / steps can be further broken down, and some operations / steps can be combined or partially combined, so the actual execution order can be changed according to actual conditions.

[0025] It should be noted that "multiple" referred to herein means two or more. The association relationship of "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the three cases of A alone, A and B together, and B alone. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0026] The implementation details of the technical solutions of the embodiments of the present application are described in detail below:

[0027] First of all, it should be noted that the electroslag ingot smelting and forging manufacturing method proposed in the present application can be applied to the technical field of electroslag smelting, for example, the existing electroslag ingot manufacturing method has a large defect area and a low material yield, therefore, how to improve the material yield of the electroslag ingot is particularly important.

[0028] According to an aspect of the present application, an electroslag ingot smelting and forging manufacturing method is provided, Figure 1 A flow chart of the electroslag ingot smelting and forging manufacturing method according to the embodiment of the present application, which can be executed by a device with computing processing function, includes at least steps 110 to 150, which are described in detail as follows:

[0029] Please refer to Figure 1 In step 110, the initial melting rate V1 of the electrode is controlled at 540 kg / h-560 kg / h, and the initial flow rate Q1 of the crystallizer cooling water is controlled at 280 m 3 / h-300 m 3 / h within 0-45 min of the electrode melting process.

[0030] In the present application, the initial melting rate V1 of the electrode is controlled in the initial stage of electroslag ingot smelting, the internal heat accumulation is reduced, and the internal good solidification structure is ensured. And the initial flow rate Q1 of the cooling water is appropriately reduced to reduce the cooling intensity of the bottom of the electroslag ingot, so as to reduce the generation depth of surface defects. The generation of defects at the bottom of the electroslag ingot can be reduced, thereby improving the forming quality of the electroslag ingot.

[0031] Electroslag remelting is a secondary refining technology. A molten slag is contained in a copper water-cooled crystallizer. A consumable electrode is inserted into the slag. The consumable electrode, the slag pool, the metal pool, the ingot (electroslag ingot), and the bottom water tank form a loop through the short net lead and the transformer. During the power-on process, the slag pool releases Joule heat to gradually melt the consumable electrode. The molten metal gathers into droplets, passes through the slag pool, and falls into the crystallizer to form a metal pool. The metal pool rapidly solidifies under the action of cooling water to form an electroslag ingot.

[0032] In step 120, after the electrode melting process lasts for 45 min, the stable melting rate V2 of the electrode is controlled at 580 kg / h-600 kg / h, and the stable flow rate Q2 of the crystallizer cooling level is controlled at 350 m 3 / h-400 m 3 / h, until the electroslag ingot is smelted and formed.

[0033] In the present application, after the bottom of the electroslag ingot is formed, appropriately increasing the stable melting rate V2 of the electrode and the stable flow rate Q2 of the crystallizer cooling level can effectively improve the smelting forming speed of the whole electroslag ingot and improve the overall product quality.

[0034] It should be emphasized that, in the whole electroslag ingot production process, under the premise that the water quantity of the crystallizer is consistent, the cooling intensity of the upper region of the electroslag ingot is lower than that of the edge and the bottom. According to the influence law of the cooling intensity on the internal and surface quality of the electroslag ingot, the surface quality of the bottom of the electroslag ingot is the worst. The cooling intensity at this position is large, and there is a competitive solidification phenomenon between the high-melting-point phase of the slag and the electroslag ingot. Therefore, there are many pit defects on the surface of the corresponding electroslag ingot, which become folds, and iron oxide scale is rolled in, etc., to form forging defects.

[0035] Please refer to Figure 2 , Figure 2 According to the cooling intensity and local solidification time diagram corresponding to each position in the electroslag ingot production process shown in the embodiments of the present application. It can be seen from the diagram that the overall solidification stability of the electroslag ingot can be improved by the manufacturing method of the present application.

[0036] In step 130, when the electroslag ingot is formed and forged, the electroslag ingot is forged from the middle position of the axial direction to both ends of the electroslag ingot until a step protruding in the radial direction of the electroslag ingot is forged at the bottom of the electroslag ingot.

[0037] In the present application, since defects are prone to occur at the bottom of the electroslag ingot, forging is performed from the middle position to both ends in the axial direction, which can extrude the internal defects existing at the bottom outward, and is beneficial to improving the yield.

[0038] It should be emphasized that reference should be made to Figure 3 , Figure 3 The figure of the change of the point position of the electroslag ingot before and after the first deformation of the electroslag ingot according to the embodiment of the present application and the corresponding equivalent stress diagram are shown. Figure 3 It can be seen that the displacement characteristics of the points at the bottom of the electroslag ingot in the forging process are calculated by the simulation software, and after the first deformation, it can be seen from the change of the taken point position that the metal flow is more obvious near the edge of the electroslag ingot, the P1 and P8 points at the edge have obvious offset in the transverse direction, and the equivalent stress at the two points is larger, and the degree of deformation is larger; while the metal flow near the center of the electroslag ingot is poor, the offset degree of the P4 and P5 points at the center is small, and the corresponding equivalent stress is small, and the degree of deformation is smaller.

[0039] Reference should be made to Figure 4 and Figure 5 , Figure 4 The equivalent stress distribution diagram of the electroslag ingot in the first deformation process of the electroslag ingot according to the embodiment of the present application is shown, Figure 5 The metal flow line distribution diagram of the electroslag ingot in the first deformation process of the electroslag ingot according to the embodiment of the present application is shown. Through the simulation calculation and the verification of the surface defect position of the entity electroslag ingot, it is found that within the range of 200mm in height at the bottom of the electroslag ingot, it is a surface defect intensive area, and the defects are more obvious near the bottom; the depth of the surface pit is related to the cooling intensity. In the traditional forging mode, the defect range at the bottom is large, and the volume to be removed for removing the defects is large, which seriously affects the yield.

[0040] Reference should be made to Figure 6 , Figure 6 The figure of removing the step of the electroslag ingot according to the embodiment of the present application is shown. In step 140, the step is cut off along the circumferential direction of the electroslag ingot.

[0041] In the present application, by taking advantage of the characteristics that the bottom has defects on the outside but is relatively good on the inside, the forging material near the bottom with more surface defects is left with a certain radial size allowance, and the surface defects are removed by machining, and most of the material without defects is retained, which can effectively improve the yield of the electroslag ingot. The step defects of the electroslag ingot are concentrated, and after the step is cut off, the defects of the electroslag ingot can be removed in a large area, and the quality of the finished product of the electroslag ingot is improved.

[0042] In step 150, the end part of the electroslag ingot is detected, and the defect part determined by the detection is cut off.

[0043] In the application, the end of the electroslag ingot is subjected to flaw detection treatment, the part with defects after machining is removed as a whole, and the utilization rate of the material and the quality of the finished product can be significantly improved.

[0044] In an embodiment of the application, the step of forging the protruding electroslag ingot radially at the bottom of the electroslag ingot includes: if the cross section of the electroslag ingot is circular, the width W1 of the step is controlled to be 200×D1 / D0 2 / D0 2 wherein D1 is the diameter of the step, D0 is the diameter of the electroslag ingot, the height H1 of the step is controlled to be 0.05D0; if the cross section of the electroslag ingot is square, the width W2 of the step is controlled to be 50×πL1 / L0 2 / L0 2 wherein L1 is the side length of the step, L0 is the side length of the electroslag ingot, the height H2 of the step is controlled to be 0.05L0.

[0045] In the application, the electroslag ingot is usually a cylinder after forming, and is a cylinder with a circular cross section or a cuboid with a square cross section after forging according to needs, if the cross section of the electroslag ingot after forging is circular, the width W1 of the step is controlled to be 200×D 2 / D0 2 wherein D is the diameter before forging, D0 is the diameter after forging, the height H1 of the step is controlled to be 0.05D0;

[0046] if the cross section of the electroslag ingot after forging is square, the width W2 of the step is controlled to be 50×πD 2 / L0 2 wherein D is the diameter before forging, L0 is the side length of the cross section after forging, the height H2 of the step is controlled to be 0.05L0;

[0047] The step is controlled within the range, which can effectively concentrate the defects in the step and guarantee the quality stability of the electroslag ingot.

[0048] In an embodiment of the application, before the electroslag ingot is formed and forged, the method further includes: heating the electroslag ingot, and controlling the heating temperature of the electroslag ingot to be 1150-1300℃ and the heating time of the electroslag ingot to be 15-36h.

[0049] In the application, the electroslag ingot is heated before forging, and the control of the heating time is beneficial to improve the temperature of the electroslag ingot as a whole, facilitate the forging of the electroslag ingot, and improve the forging efficiency of the electroslag ingot.

[0050] In an embodiment of the application, the end of the electroslag ingot is subjected to flaw detection, and the defect position determined by the flaw detection is cut off, and the method includes: using an ultrasonic detector to detect the end of the electroslag ingot, and cutting off the defect position determined by the flaw detection.

[0051] In the application, the ultrasonic detector has strong flaw detection stability, and can effectively detect the defect depth of the electroslag ingot.

[0052] In an embodiment of the application, when the electroslag ingot is formed and forged, the electroslag ingot is forged by using a free forging method.

[0053] In the application, the free forging method has good versatility and can effectively save processing cost.

[0054] In an embodiment of the application, during the electrode melting process, 38 kg of slag is added for every 1 t of electrode, and the mass percentage of CaF2 and Al2O3 in the slag is 7:3.

[0055] In the application, the slag plays a role of heating, and CaF2 and Al2O3 in the slag can effectively generate a large amount of heat to make the electrode melt smoothly.

[0056] In an embodiment of the application, in the electroslag ingot, the total mass percentage of Si, Cr, Ni, Mo, V and Mn is 4.5%-10.5% of the total mass of the electroslag ingot.

[0057] In the application, the total mass percentage of Si, Cr, Ni, Mo, V and Mn is 4.5%-10.5%, and the overall alloy cost of the electroslag ingot is relatively high, and the manufacturing method of the application can more obviously reduce the manufacturing cost.

[0058] In an embodiment of the application, the diameter of the crystallizer is 540 mm-730 mm, and the mass of the electroslag ingot is 3 t-10 t.

[0059] The diameter of the crystallizer is 540 mm-730 mm, the mass of the electroslag ingot is 3 t-10 t, and the manufacturing method of the application can obviously improve the yield of the electroslag ingot.

[0060] Through the test of the electroslag ingot of different specifications by the method, the yield improvement value of the electroslag ingot as a whole is shown in Table 1:

[0061] Table 1: Yield improvement value of electroslag ingot of different specifications

[0062]

[0063] From Table 1, it can be seen that, compared with the traditional smelting and forging manufacturing method, the manufacturing method of the application can effectively improve the yield of the electroslag ingot, the yield of the electroslag ingot is increased by 3.2%-6.4%, the resource utilization rate is improved, and the production cost is reduced.

[0064] In summary, the initial melting rate V1 of the electrode is controlled at 540kg / h-560kg / h in the first 45 minutes of electrode melting, and the initial flow rate Q1 of the crystallizer cooling water is controlled at 280m 3 / h-300m 3 / h, which appropriately reduces the cooling intensity of the bottom of the electroslag ingot to reduce the depth of surface defects and the accumulation of internal heat, thereby ensuring good internal solidification of the electroslag ingot in the initial stage. After 45 minutes of electrode melting, the bottom of the electroslag ingot is completely solidified, and the stable melting rate V2 of the electrode is controlled at 580kg / h-600kg / h, and the stable flow rate Q2 of the crystallizer cooling water is controlled at 350m 3 / h-400m 3 / h, which improves the overall solidification of the electroslag ingot. After the electroslag ingot is formed, forging is performed from the middle position to both ends in the axial direction, which extrudes the internal defects in the bottom outward, thereby improving the yield rate. In the final forging process, the bottom of the electroslag ingot has defects in the outer part but is relatively good in the inner part, and the material near the bottom with more surface defects is left with a certain radial size allowance, and is machined to remove the surface defects, and the material without defects is retained. At the same time, the material with defects after machining is removed as a whole, which significantly improves the utilization rate of the material and the quality of the finished product.

[0065] It should be understood that the present application is not limited to the precise construction which has been described above and illustrated in the accompanying drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims

1. A manufacturing method for electroslag ingot smelting and forging, characterized in that, The method includes: During the electrode melting process (0-45 min), the initial melting rate V1 is controlled between 540 kg / h and 560 kg / h, and the initial flow rate Q1 of the crystallizer cooling water is controlled between 280 m³ / h. 3 / h-300m 3 / h; After 45 minutes of electrode melting, the electrode melting rate V2 was controlled at 580 kg / h-600 kg / h, and the cooling water flow rate Q2 of the crystallizer was controlled at 350 m³ / h. 3 / h-400m 3 / h, until the electroslag ingot is smelted and formed; When forming and forging the electroslag ingot, the electroslag ingot is forged from the middle position in the axial direction towards both ends of the electroslag ingot until a step protruding radially from the bottom of the electroslag ingot is forged. The step is cut off along the circumferential direction of the electroslag ingot; The end of the electroslag ingot is subjected to flaw detection, and the defective parts identified by the flaw detection are removed. The method of forging a step protruding radially from the bottom of the electroslag ingot includes: If the cross-section of the electroslag ingot after forging is circular, then the width of the step should be controlled as W1 = 200 × D. 2 / D0 2 Where D is the diameter of the electroslag ingot before forging, D0 is the diameter of the electroslag ingot after forging, and the height of the step is controlled to be H1=0.05D0; If the cross-section of the electroslag ingot after forging is square, then the width of the step should be controlled as W2 = 50 × πD. 2 / L0 2 Where D is the diameter of the electroslag ingot before forging, L0 is the side length of the cross-section of the electroslag ingot after forging, and the height of the step is controlled to be H2=0.05L0.

2. The method according to claim 1, characterized in that, Before electroslag ingot forming and forging, the method further includes: The electroslag ingot is heated, and the heating temperature of the electroslag ingot is controlled at 1150℃-1300℃, and the heating time of the electroslag ingot is controlled at 15h-36h.

3. The method according to claim 1, characterized in that, The method of performing flaw detection on the end of the electroslag ingot and removing the defective parts identified by the flaw detection includes: The ends of the electroslag ingot are inspected using an ultrasonic detector, and the defective parts identified by the inspection are removed.

4. The method according to claim 1, characterized in that, When forming and forging the electroslag ingot, the electroslag ingot is forged using a free forging method.

5. The method according to any one of claims 1-4, characterized in that, During the electrode melting process, 38 kg of slag is added for every 1 t of electrode melted, and the mass percentage of CaF2 and Al2O3 in the slag is 7:

3.

6. The method according to any one of claims 1-4, characterized in that, In the electroslag ingot, the sum of the masses of Si, Cr, Ni, Mo, V and Mn accounts for 4.5%-10.5% of the total mass of the electroslag ingot.

7. The method according to any one of claims 1-4, characterized in that, The diameter of the crystallizer is 540mm-730mm.

8. The method according to claim 7, characterized in that, The mass of the electroslag ingot is 3t-10t.

Images