Forging method for improving electroslag ingot shrinkage cavity

Abstract

A forging method for improving electroslag ingot shrinkage cavities comprises the steps that (1) flaw detection is conducted on an electroslag ingot cold ingot so as to determine the depth H of an open shrinkage cavity, a dark shrinkage cavity or a serious looseness at the head of the electroslag ingot; (2) the electroslag ingot is heated to the forging heating temperature; (3) the electroslag ingot is vertically placed, the tail portion faces downwards, and the head portion faces upwards; (4) one side of the head of the electroslag ingot is subjected to pressing deformation within the range of 0.1-0.45 D away from the edge of the electroslag ingot, D is the diameter of the head of the electroslag ingot, and the pressing height is H; one side of the head of the electroslag ingot is pressed down after pressing deformation, and the central position of the head of the electroslag ingot protrudes relative to the periphery of the visible shrinkage cavity, the hidden shrinkage cavity or the seriously loose area on the side; 5, the electroslag ingot is rotated by 90 DEG C along the axis of the electroslag ingot, then the operation is repeated according to the step 3 and the step 4, after multiple times of pressing deformation, a circle around the head of the electroslag ingot is pressed down, and an open shrinkage cavity, a dark shrinkage cavity or a seriously loose area in the center protrudes relative to the circle around the electroslag ingot, and 6, the protruding part is cut off through a hot cutting mincing knife of a high-speed forging machine.

Description

Technical Field

[0001] This invention relates to the field of forging, and more specifically to a forging method for improving shrinkage cavities in electroslag ingots. Background Technology

[0002] As industries such as aerospace, defense, energy equipment, high-end mold manufacturing, heavy machinery, and petrochemicals place increasingly higher demands on the quality of special steel materials, electroslag steel, as a high-quality special steel material, is being used in a wider range of applications and is gradually developing towards larger sizes. Furthermore, the weight of electroslag steel ingots is increasing, and the diameter of electroslag ingots is also increasing.

[0003] As the diameter of electroslag ingots increases, varying degrees of visible shrinkage cavities, invisible shrinkage cavities, or severe porosity often appear at the final solidification end, i.e., the riser end. This seriously hinders the improvement of electroslag ingot forging quality and material utilization, resulting in huge quality losses and a rapid increase in production costs.

[0004] When forging electroslag ingots, forging plants formulate forging heating processes, forging deformation processes, and post-forging cooling and annealing processes based on the chemical composition of the ingot, its size, and the user's requirements for the material's dimensions, microstructure, and properties. The electroslag ingot heating process typically involves a two- to three-stage slow heating to the forging temperature, followed by a holding period depending on the ingot size and steel grade. After holding, multiple upsetting and drawing forging processes are performed until the ingot is produced to the user's ordered dimensions. Following the finished product dimensions, post-forging heat treatment processes such as cooling, normalizing, and annealing are then executed.

[0005] As is well known, during the forging upsetting-drawing process of electroslag ingots, visible shrinkage cavities, hidden shrinkage cavities, or severe porosity at the riser of the electroslag ingot can be inherited by the forged finished product. Due to the presence of visible shrinkage cavities, hidden shrinkage cavities, or severe porosity in the electroslag ingot, the forged finished product will have defects exceeding the standard during subsequent flaw detection or end surface inspection of the forging material, and the defects need to be removed. The removal of end defects of the forged finished product leads to a significant decrease in the utilization rate of the forging material.

[0006] When addressing issues such as visible shrinkage cavities, hidden shrinkage cavities, or severe porosity at the head of electroslag ingots, engineers typically employ electroslag remelting process control during the feeding process to improve these problems at the ingot riser.

[0007] Chinese patent CN201810968696.5 discloses a "heavy electroslag remelting production process." In conventional electroslag ingot production, to improve the quality of the final solidification end (riser end) and based on the electroslag remelting control process during the feeding phase, the traditional process control method for the feeding phase involves gradually reducing voltage and current and narrowing the molten pool depth from the start of feeding to the end of smelting. Because the water-cooling strength remains stable throughout the remelting stage, the riser end of the produced electroslag ingots exhibits varying degrees of visible shrinkage cavities, hidden shrinkage cavities, or severe porosity, hindering the improvement of forging quality and material utilization. This invention, while maintaining constant water-cooling strength, reduces voltage and current at the beginning of the feeding phase. Depending on the ingot type and feeding time, the voltage and current are increased for a certain period before the end of feeding to raise the remelting slag temperature, delaying the solidification time of the uppermost molten steel. This ensures sufficient molten steel fills the riser end of the electroslag ingot, fully compensating for the voids formed during the solidification of the ingot body, thereby improving the riser quality.

[0008] Based on the patent search results, existing patents typically address the issues of visible shrinkage cavities, hidden shrinkage cavities, or severe porosity at the head of electroslag ingots by controlling the electroslag remelting process during the feeding process in the electroslag remelting process. This aims to improve the problem of visible shrinkage cavities, hidden shrinkage cavities, or severe porosity at the riser of the electroslag ingot. Summary of the Invention

[0009] The purpose of this invention is to provide a forging method that improves the shrinkage cavity of electroslag ingots, and to solve the problems of excessive flaw detection equivalent of forged products caused by obvious shrinkage cavities, dark shrinkage cavities or severe porosity at the head of electroslag ingots during the forging process.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows: A forging method for improving shrinkage cavities in electroslag ingots, comprising the following steps: 1) Perform flaw detection on the electroslag ingot cold ingot to determine the depth H of visible shrinkage cavities, hidden shrinkage cavities, or severe porosity at the head of the electroslag ingot, in mm; 2) Heat the electroslag ingot to the forging heating temperature and hold it at that temperature until the temperature inside the electroslag ingot is uniform; 3) Place the electroslag ingot vertically with the tail end facing down and the head end facing up, and place the tail end of the electroslag ingot on a flat mobile forging platform. 4) Using a flat anvil on a high-speed forging machine, perform localized compression deformation on one side of the electroslag ingot head within a range of 0.1~0.45D from the edge of the electroslag ingot head. Here, D is the diameter of the electroslag ingot head in mm, and the compression height is H in mm. H is the depth of the visible shrinkage cavity, hidden shrinkage cavity, or severely porous area on the electroslag ingot head. After localized compression deformation, one side of the electroslag ingot head is compressed, and the visible shrinkage cavity, hidden shrinkage cavity, or severely porous area on the corresponding side of the center position of the electroslag ingot head protrudes relative to its surroundings. 5) After rotating the electroslag ingot 90 degrees along its axis, repeat the operation in steps 3) and 4). The other side of the head of the electroslag ingot is pressed down, so that the visible shrinkage hole, hidden shrinkage hole or severely loose area at the center of the head of the electroslag ingot protrudes relative to the surrounding area. Through multiple local pressing deformations, the entire ring around the center of the head of the electroslag ingot is pressed down, so that the visible shrinkage hole, hidden shrinkage hole or severely loose area at the center of the head of the electroslag ingot protrudes relative to the surrounding ring. 6) Use the hot cutting blade of the high-speed forging machine to cut off the protruding part at the center of the head of the electroslag ingot, namely the visible shrinkage hole, the hidden shrinkage hole or the severely loose part. At this point, all the visible shrinkage holes, the hidden shrinkage holes or the severely loose parts on the electroslag ingot have been removed.

[0011] Preferably, in step 4), the two sides of the head of the electroslag ingot are simultaneously pressed and deformed within a range of 0.1~0.45D from the edge of the head of the electroslag ingot using the flat anvil on the high-speed forging machine, so that the visible shrinkage holes, hidden shrinkage holes or severely loose areas on both sides of the center position of the head of the electroslag ingot protrude relative to their surroundings.

[0012] Preferably, the forging heating temperature is 1000~1300℃.

[0013] In the forging method described in this invention: First, the electroslag ingot is inspected to determine the depth H of visible shrinkage cavities, hidden shrinkage cavities, or severe porosity at the head of the electroslag ingot, providing a basis for the subsequent forging process to remove the shrinkage cavity depth.

[0014] When the electroslag ingot is removed from the furnace for forging after the high-temperature holding stage, it is placed upright with the tail facing down and the head facing up, with the tail placed on the forging platform. Using a high-speed forging machine's flat anvil, the head of the electroslag ingot is subjected to multiple localized deformations to locally compress and deform the area around it. After these multiple localized deformations, the area around the head of the electroslag ingot is compressed, and the central visible shrinkage cavity, hidden shrinkage cavity, or severely porous area of ​​the head protrudes relative to the surrounding area. The protruding part (visible shrinkage cavity, hidden shrinkage cavity, or severely porous part) is then removed using a hot-cutting blade on the high-speed forging machine. This removes the visible shrinkage cavity, hidden shrinkage cavity, or severely porous part, thus avoiding its impact on the subsequent forging of the finished product and greatly improving material utilization.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: Traditional forging mainly improves the internal quality of metals through forging deformation, while obtaining optimal mechanical properties.

[0016] The forging method described in this invention differs from traditional forging methods in that it employs multiple local deformations. This process exposes defects that were originally present inside the metal material and could not be eliminated by traditional forging methods to the outside of the metal material. Then, physical methods are used to remove the defects, thus avoiding the impact of the defects on the overall performance of the material.

[0017] Simply put, traditional forging methods aim to improve the overall performance of metal materials. The forging method described in this invention aims to physically remove defects that traditional forging methods cannot improve, so as to avoid the adverse effects of visible shrinkage cavities, hidden shrinkage cavities, or severely porous parts on the quality of forged products and the improvement of material utilization. Attached Figure Description

[0018] Figures 1-7 This is a schematic diagram of the forging method described in this invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0020] See Figures 1-7 The forging method for improving shrinkage cavities in electroslag ingots according to the present invention includes the following steps: 1) Perform flaw detection on the electroslag ingot cold ingot to determine the depth H of visible shrinkage cavities, hidden shrinkage cavities, or severe porosity at the head of the electroslag ingot, in mm; 2) Heat the electroslag ingot to the forging heating temperature and hold it at that temperature until the temperature inside the electroslag ingot is uniform; 3) Place the electroslag ingot vertically with the tail end facing down and the head end facing up, and place the tail end of the electroslag ingot on a flat mobile forging platform. 4) Using a flat anvil on a high-speed forging machine, perform localized compression deformation on one side of the electroslag ingot head within a range of 0.1~0.45D from the edge of the electroslag ingot head. Here, D is the diameter of the electroslag ingot head in mm, and the compression height is H in mm. H is the depth of the visible shrinkage cavity, hidden shrinkage cavity, or severely porous area on the electroslag ingot head. After localized compression deformation, one side of the electroslag ingot head is compressed, and the visible shrinkage cavity, hidden shrinkage cavity, or severely porous area on the corresponding side of the center position of the electroslag ingot head protrudes relative to its surroundings. 5) Rotate the electroslag ingot 90 degrees along its axis and repeat steps 3) and 4) once. The other side of the head of the electroslag ingot is pressed down, so that the visible shrinkage hole, hidden shrinkage hole or severely loose area at the center of the head of the electroslag ingot protrudes relative to the surrounding area. Through multiple local pressing deformations, the entire ring around the center of the head of the electroslag ingot is pressed down, so that the visible shrinkage hole, hidden shrinkage hole or severely loose area at the center of the head of the electroslag ingot protrudes relative to the surrounding ring. 6) Use the hot cutting blade of the high-speed forging machine to cut off the protruding part at the center of the head of the electroslag ingot, namely the visible shrinkage hole, the hidden shrinkage hole or the severely loose part. At this point, all the visible shrinkage holes, the hidden shrinkage holes or the severely loose parts on the electroslag ingot have been removed.

[0021] Preferably, in step 4), the two sides of the head of the electroslag ingot are simultaneously pressed and deformed within a range of 0.1~0.45D from the edge of the head of the electroslag ingot using the flat anvil on the high-speed forging machine, so that the visible shrinkage holes, hidden shrinkage holes or severely loose areas on both sides of the center position of the head of the electroslag ingot protrude relative to their surroundings.

[0022] Preferably, the forging heating temperature is 1000~1300℃.

[0023] Example 1 A forging method for improving shrinkage cavities in electroslag ingots, wherein the electroslag ingots are ф1200mm in diameter, 2200mm in length, and made of H13 steel; the method includes the following steps: 1) Perform flaw detection on the electroslag ingot cold ingot to determine the depth H of the visible shrinkage cavity, hidden shrinkage cavity or severe porosity at the head of the electroslag ingot to be 295mm. 2) Heat the electroslag ingot to the forging heating temperature of 1290℃ and hold it at that temperature until the temperature inside the electroslag ingot is uniform. 3) Place the electroslag ingot vertically with the tail end facing down and the head end facing up, and place the tail end of the electroslag ingot on a flat mobile forging platform. 4) Use the flat anvil on the high-speed forging machine to perform local compression deformation on one side of the head of the electroslag ingot, within a range of 500mm from the edge of the head of the electroslag ingot, with a compression height of H, i.e., 295mm; after local compression deformation, one side of the head of the electroslag ingot is compressed, and the center position of the head of the electroslag ingot corresponds to the visible shrinkage cavity, dark shrinkage cavity, or severely loose area on this side protruding relative to its surroundings. 5) After rotating the electroslag ingot 90 degrees along its axis, repeat the operation in steps 3) and 4). The other side of the head of the electroslag ingot is pressed down, so that the visible shrinkage hole, hidden shrinkage hole or severely loose area at the center of the head of the electroslag ingot protrudes relative to the surrounding area. Through multiple local pressing deformations, the entire ring around the center of the head of the electroslag ingot is pressed down, so that the visible shrinkage hole, hidden shrinkage hole or severely loose area at the center of the head of the electroslag ingot protrudes relative to the surrounding ring. 6) Use the hot cutting blade of the high-speed forging machine to cut off the protruding part at the center of the head of the electroslag ingot, namely the visible shrinkage hole, the hidden shrinkage hole or the severely loose part. At this point, all the visible shrinkage holes, the hidden shrinkage holes or the severely loose parts on the electroslag ingot have been removed.

[0024] The finished product flaw detection results showed no flaws and the shrinkage cavities were removed.

[0025] Example 2 A forging method for improving shrinkage cavities in electroslag ingots, wherein the electroslag ingots are ф1000mm in diameter, 2100mm in length, and made of G115 steel; the method includes the following steps: 1) Perform flaw detection on the electroslag ingot cold ingot to determine the depth H of the visible shrinkage cavity, hidden shrinkage cavity or severe porosity at the head of the electroslag ingot to be 350mm. 2) Heat the electroslag ingot to the forging heating temperature of 1020℃ and hold it at that temperature until the temperature inside the electroslag ingot is uniform. 3) Place the electroslag ingot vertically with the tail end facing down and the head end facing up, and place the tail end of the electroslag ingot on a flat mobile forging platform. 4) Using the flat anvil on the high-speed forging machine, the two sides of the head of the electroslag ingot are simultaneously pressed and deformed within a range of 150mm from the edge of the head of the electroslag ingot, with a pressing height of H, i.e. 350mm; so that the visible shrinkage holes, hidden shrinkage holes or severely loose areas on both sides of the center position of the head of the electroslag ingot protrude relative to the surrounding area. 5) Rotate the electroslag ingot 90 degrees along its axis and repeat steps 3) and 4) once. The other side of the head of the electroslag ingot is pressed down, so that the visible shrinkage hole, hidden shrinkage hole or severely loose area at the center of the head of the electroslag ingot protrudes relative to the surrounding area. Through multiple local pressing deformations, the entire ring around the center of the head of the electroslag ingot is pressed down, so that the visible shrinkage hole, hidden shrinkage hole or severely loose area at the center of the head of the electroslag ingot protrudes relative to the surrounding ring. 6) Use the hot cutting blade of the high-speed forging machine to cut off the protruding part at the center of the head of the electroslag ingot, namely the visible shrinkage hole, the hidden shrinkage hole or the severely loose part. At this point, all the visible shrinkage holes, the hidden shrinkage holes or the severely loose parts on the electroslag ingot have been removed.

[0026] The finished product flaw detection results showed no flaws and the shrinkage cavities were removed.

[0027] Example 3 A forging method for improving shrinkage cavities in electroslag ingots, wherein the electroslag ingots are φ900mm in diameter, 2000mm in length, and made of G115 steel; the method includes the following steps: 1) Perform flaw detection on the electroslag ingot cold ingot to determine the depth H of the visible shrinkage hole, hidden shrinkage hole or severe porosity at the head of the electroslag ingot to be 450mm. 2) Heat the electroslag ingot to the forging heating temperature of 1150℃ and hold it at that temperature until the temperature inside the electroslag ingot is uniform. 3) Place the electroslag ingot vertically with the tail end facing down and the head end facing up, and place the tail end of the electroslag ingot on a flat mobile forging platform. 4) The flat anvil on the high-speed forging machine simultaneously presses down and deforms the two sides of the electroslag ingot head within a range of 300mm from the edge of the electroslag ingot head. Here, D is the diameter of the electroslag ingot head in mm, and the pressing height is H, which is 450mm. This causes the visible shrinkage holes, hidden shrinkage holes, or severely loose areas on both sides of the center position of the electroslag ingot head to bulge relative to their surroundings. 5) Rotate the electroslag ingot 90 degrees along its axis and repeat steps 3) and 4) once. The other side of the head of the electroslag ingot is pressed down, so that the visible shrinkage hole, hidden shrinkage hole or severely loose area at the center of the head of the electroslag ingot protrudes relative to the surrounding area. Through multiple local pressing deformations, the entire ring around the center of the head of the electroslag ingot is pressed down, so that the visible shrinkage hole, hidden shrinkage hole or severely loose area at the center of the head of the electroslag ingot protrudes relative to the surrounding ring. 6) Use the hot cutting blade of the high-speed forging machine to cut off the protruding part at the center of the head of the electroslag ingot, namely the visible shrinkage hole, the hidden shrinkage hole or the severely loose part. At this point, all the visible shrinkage holes, the hidden shrinkage holes or the severely loose parts on the electroslag ingot have been removed.

[0028] The finished product flaw detection results showed no flaws and the shrinkage cavities were removed.

Claims

1. A forging method for improving shrinkage cavities in electroslag ingots, characterized in that, Includes the following steps: 1) Perform flaw detection on the electroslag ingot cold ingot to determine the depth H of visible shrinkage cavities, hidden shrinkage cavities, or severe porosity at the head of the electroslag ingot, in mm; 2) Heat the electroslag ingot to the forging heating temperature and hold it at that temperature until the temperature inside the electroslag ingot is uniform; 3) Place the electroslag ingot vertically with the tail end facing down and the head end facing up, and place the tail end of the electroslag ingot on the forging platform. 4) Using a flat anvil on a high-speed forging machine, perform localized compression deformation on one side of the electroslag ingot head within a range of 0.1~0.45D from the edge of the electroslag ingot head. Here, D is the diameter of the electroslag ingot head in mm, and the compression height is H in mm. H is the depth of the visible shrinkage cavity, hidden shrinkage cavity, or severely porous area on the electroslag ingot head. After localized compression deformation, one side of the electroslag ingot head is compressed, and the visible shrinkage cavity, hidden shrinkage cavity, or severely porous area on the corresponding side of the center position of the electroslag ingot head protrudes relative to its surroundings. 5) After rotating the electroslag ingot 90 degrees along its axis, repeat the operation in steps 3) and 4). The other side of the head of the electroslag ingot is pressed down, so that the visible shrinkage hole, hidden shrinkage hole or severely loose area at the center of the head of the electroslag ingot protrudes relative to the surrounding area. Through multiple local pressing deformations, the entire ring around the center of the head of the electroslag ingot is pressed down, so that the visible shrinkage hole, hidden shrinkage hole or severely loose area at the center of the head of the electroslag ingot protrudes relative to the surrounding ring. 6) Use the hot cutting blade of the high-speed forging machine to cut off the protruding part at the center of the head of the electroslag ingot, namely the visible shrinkage hole, the hidden shrinkage hole or the severely loose part. At this point, all the visible shrinkage holes, the hidden shrinkage holes or the severely loose parts on the electroslag ingot have been removed.

2. The forging method for improving shrinkage cavities in electroslag ingots as described in claim 1, characterized in that, Step 4) Using the flat anvil on the high-speed forging machine, the two sides of the electroslag ingot head are simultaneously pressed down and deformed within a range of 0.1~0.45D from the edge of the electroslag ingot head, so that the visible shrinkage holes, hidden shrinkage holes or severely loose areas on both sides of the center position of the electroslag ingot head protrude relative to the surrounding area.

3. The forging method for improving shrinkage cavities in electroslag ingots as described in claim 1, characterized in that, The forging heating temperature is 1000~1300℃.

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