Method of forming a transverse cross-sectioned austenitic stainless steel forging

Abstract

This invention relates to the field of austenitic stainless steel forging and discloses a method for forming transversely variable cross-section austenitic stainless steel forgings. The method includes the following steps: forging a billet into a flat billet, wherein the sides of the flat billet form opposing first and second side surfaces; forging a raised structure on the first side surface of the flat billet by forging the sides corresponding to the raised structure of the forging, forming a stepped billet; forging a concave structure on the second side surface of the stepped billet by forging the corresponding positions of the raised structure, and further deforming the entire billet to form the final forging. This application uses an integral forging method for transversely variable cross-section austenitic stainless steel forgings, which can ensure that the grains in all parts of the forging are fine and uniform, solve the problem of excessive forging load in large-section stepped austenitic stainless steel, reduce the difficulty of deformation, and prevent severe surface cracking during the forging process of austenitic stainless steel.

Description

Technical Field

[0001] This invention relates to the field of austenitic stainless steel forging, and in particular to a method for forming transversely variable cross-section austenitic stainless steel forgings. Background Technology

[0002] Large austenitic stainless steel forgings are generally characterized by their large size, complex shape, and high technical requirements. To ensure the performance requirements such as fine grains inside the forgings, austenitic stainless steel forgings are often forged into relatively simple shapes such as blocks, plates, and discs. For large-sized variable cross-section austenitic stainless steel forgings, due to their more complex structure, the forging difficulty is extremely high due to limitations in material properties, equipment capabilities, and performance requirements. It is impossible to forge them to a qualified state using conventional forging methods. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for forming transversely variable cross-section austenitic stainless steel forgings, which reduces the forging difficulty while ensuring the performance of the forgings.

[0004] The present invention discloses a method for forming a transversely variable cross-section austenitic stainless steel forging. The forging has a raised structure on its first side and a recessed structure on its second side corresponding to the raised structure. The second side of the forging is the surface opposite to the first side. The method for forming a transversely variable cross-section austenitic stainless steel forging includes the following steps:

[0005] The billet is forged into a flat billet, the sides of which form opposing first and second sides;

[0006] A raised structure is forged on the first side of a flat blank by forging the two sides of the raised structure corresponding to the forging, thus forming a stepped blank.

[0007] On the second side of the stepped blank, the corresponding position of the protruding structure is forged to form an inner concave structure, and then further deformed as a whole to form the final forging.

[0008] Preferably, the first side of the forging has a raised structure, and the second side of the forging has a concave structure corresponding to the position of the raised structure; the shape of the first side with the raised structure is formed first, and then the shape of the second side with the concave structure is formed.

[0009] Preferably, when forming the shape of the second side with a concave structure, the height of the protruding structure formed on the first side is increased.

[0010] Preferably, the stepped billet is forged into the final forging in two stages;

[0011] During the first forging process, a second side profile with a concave structure is formed.

[0012] The height of the raised structure in the forging is further increased during the second forming process.

[0013] Preferably, the deformation amount of forging a billet into a flat billet is greater than the deformation amount of forging a flat billet into a stepped billet;

[0014] The deformation amount of a flat billet forged into a stepped billet is greater than the deformation amount of a stepped billet forged into a forging.

[0015] Preferably, the heating temperature for forging a billet into a flat billet is greater than the heating temperature for forging a flat billet into a stepped billet; the heating temperature for forging a flat billet into a stepped billet is greater than the heating temperature forging a stepped billet into a forging.

[0016] Preferably, when the billet is forged into a flat billet, the heating temperature of the billet is 1150-1230℃;

[0017] When a flat billet is forged into a stepped billet, the heating temperature of the flat billet is 1100~1150℃;

[0018] When forging stepped billets into forgings, the heating temperature of the stepped billets is 1100~1150℃.

[0019] Preferably, the forging temperature of the final forging of the billet into a flat billet is 1150±20℃.

[0020] Preferably, a first forging assembly is used to forge the flat billet into the stepped billet. The first forging assembly includes a first upper flat anvil and a first shaped anvil. The first shaped anvil has a first concave cavity in the middle. The first shaped anvil has a material-separating section and a drawing section arranged sequentially along the first concave cavity. The material-separating section has outwardly convex material-separating angles on both sides of the first concave cavity. The material-separating angles form a first plane on the side away from the first concave cavity. The drawing section forms a second plane on both sides of the first concave cavity. The height of the first plane is lower than the height of the second plane.

[0021] When forging a flat billet into a stepped billet, the flat billet is placed on the dividing section from one side of the dividing section of the first forging assembly. The flat billet is laterally divided by pressing down with the first upper flat anvil. The flat billet is moved so that the divided section moves to the elongation section of the first anvil and the undivided section moves to the dividing section of the first anvil. The division and elongation are continued by pressing down with the first upper flat anvil. The movement, division and elongation are repeated until the billet is completely divided and elongated, forming a stepped billet with a raised structure on the first side.

[0022] Preferably, a second forging assembly is used to forge the stepped billet into the final forging. The second forging assembly includes a second upper anvil and a second lower anvil. The second upper anvil is provided with an outward protrusion adapted to the concave structure of the forging, and the second lower anvil is provided with a second concave cavity adapted to the protruding structure of the forging.

[0023] The raised structure of the stepped blank is aligned with the second concave cavity and placed on the second lower anvil. The final forging is forged by pressing down with the second upper anvil.

[0024] Preferably, the stepped billet is forged into the final forging in two stages;

[0025] During the first forging process, a pad is placed in the second concave cavity of the second forging assembly. The raised structure of the stepped billet is aligned with the second concave cavity and placed on the second lower anvil. The forging is then performed by pressing down on the second upper anvil.

[0026] During the second forging process, the pad in the second concave cavity is removed. The raised structure of the stepped blank is aligned with the second concave cavity and placed on the second lower anvil. The second upper anvil is used to press down and forge the blank to form the final forging.

[0027] The beneficial effects of this invention are as follows: This application adopts an integral forging method for transversely variable cross-section austenitic stainless steel forgings, thereby ensuring that the grains in each part of the forging are fine and uniform. In the integral forging process, the flat billet is first forged into a raised structure on one side of the forging, so that the billet as a whole forms a stepped structure. Then, the concave structure on the other side is forged, and the billet is further deformed as a whole. This solves the problem of excessive load in forging large cross-section stepped austenitic stainless steel, reduces the difficulty of deformation, and prevents severe surface cracking during the forging process of austenitic stainless steel. Attached Figure Description

[0028] Figure 1 This is a side view of the forging in an embodiment of this application;

[0029] Figure 2 This is a front view of the forging in an embodiment of this application;

[0030] Figure 3 This is a schematic diagram of the billet pressing process;

[0031] Figure 4 This is a schematic diagram of billet upsetting;

[0032] Figure 5 This is a schematic diagram of a billet being drawn into a flat shape;

[0033] Figure 6 This is a frontal view of the first type;

[0034] Figure 7This is a side view of the first type;

[0035] Figure 8 This is a front view of a flat billet being forged into a stepped billet;

[0036] Figure 9 This is a side view of a flat billet being forged into a stepped billet;

[0037] Figure 10 This is a schematic diagram of the second type of anvil;

[0038] Figure 11 This is a schematic diagram of the second type of anvil;

[0039] Figure 12 This is a schematic diagram of the first forging deformation of a stepped billet into a forging;

[0040] Figure 13 yes Figure 12 A side view;

[0041] Figure 14 A schematic diagram of the first forging deformation of a stepped billet;

[0042] Figure 15 yes Figure 14 A side view;

[0043] Figure 16 This is a front view of the second forging process;

[0044] Figure 17 This is a side view diagram of the second forging process.

[0045] Reference numerals: First anvil 1, Second plane 11, Edge 12, Material dividing angle 13, Gentle slope structure 14, First plane 15, First concave cavity 16, Second upper anvil 2, Third plane 21, Side slope 22, Fourth plane 23, Second lower anvil 3, Fifth plane 31, Rounded corner 32, Cavity wall 33, Pad 4. Detailed Implementation

[0046] The present invention will be further described below.

[0047] Because the problems with austenitic stainless steel forgings mainly exist in large forgings with relatively large dimensions, this application is primarily used for forging large austenitic stainless steel forgings. However, the method of this application can also be used in relatively small forgings. Figure 1 and Figure 2 As shown, the forging has a maximum thickness of over 500mm, a minimum thickness of over 200mm, a width of over 2800mm, and a length of over 4000mm. Due to its complex shape and high grain size requirements, it is extremely difficult to forge.

[0048] In the transverse variable cross-section austenitic stainless steel forging method disclosed in this invention, the first side of the forging has a raised structure, and the second side of the forging has a concave structure corresponding to the position of the raised structure. The second side of the forging is the surface opposite to the first side. The transverse variable cross-section austenitic stainless steel forging method includes the following steps:

[0049] The billet is forged into a flat billet, the sides of which form opposing first and second sides;

[0050] A raised structure is forged on the first side of a flat blank by forging the two sides of the raised structure corresponding to the forging, thus forming a stepped blank.

[0051] On the second side of the stepped blank, the corresponding position of the protruding structure is forged to form an inner concave structure, and then further deformed as a whole to form the final forging.

[0052] The forging raw materials in this embodiment can be cast ingots, electroslag remelted ingots, etc. In the preferred embodiment of this application, after remelting the electroslag ingot, surface cracks are inspected and cleaned to prevent affecting the quality of the forging. After heating the electroslag ingot according to the heating curve, the forging clamp is then used. Figure 3 As shown.

[0053] The blank after pressing is forged into a flat blank through multiple upsetting and drawing processes. The specific shape of the flat blank is designed according to the shape of the forging. For example, if the overall projection of the forging is square, it is forged into a flat square blank; if the overall shape is round, it is forged into a disc shape.

[0054] After heating, the flat billet is first forged by pressing the two sides of the raised structure to form a raised structure on one side of the forging, making the billet into a stepped shape, i.e., the stepped billet. Then, on the second side of the stepped billet, the corresponding position of the raised structure is forged to form an inward concave structure. In this forging process, not only is the forging of the second side required, but the overall deformation also needs to be carried out simultaneously. The overall deformation includes the overall thickness, further improvement of the shape of the first side, or other local shaping optimization, so as to obtain the final forging.

[0055] In this method, during the step of forging the raised structure to form the stepped blank, the areas with the greatest deformation are on both sides of the raised structure. However, during the forging process of forming the concave structure, the areas with the greatest deformation are at both the raised and concave structures. This two-step approach not only disperses the deformation, reducing the pressure requirements on the forging equipment, but also makes the overall deformation of the forging more uniform. Furthermore, by first forming the raised structure and then forming the concave structure on the opposite side, the forming difficulty is reduced, the forming process is easier to control, and the problem of severe surface cracking during the forging of austenitic stainless steel is prevented, thus ensuring the overall forging quality. The forming process of the concave structure also allows for overall forming optimization, ensuring forming accuracy.

[0056] Although it is possible to forge the stepped billet into the final forging in a single process, the forging process is relatively difficult and requires sophisticated forging equipment, especially when the protruding structure of the forging is relatively deep. Therefore, in the preferred embodiment of this application, the stepped billet is forged into the final forging in two stages. The first forging creates the second side profile with an inwardly concave structure; the second forging further deepens the height of the protruding structure. This effectively reduces the forging difficulty, decreases the amount of deformation per forging, and prevents surface cracking.

[0057] Because this application is used for transversely variable cross-section austenitic stainless steel forgings, and the closer to forging formation, the more complex the billet shape becomes, the more advantageous it is to use a smaller deformation amount in such complex cases. Therefore, in the preferred embodiment of this application, the deformation amount of forging the billet into a flat billet is greater than the deformation amount of forging the flat billet into a stepped billet; the deformation amount of forging the flat billet into a stepped billet is greater than the deformation amount of forging the stepped billet into a forging. The smaller the deformation amount, the lower the forging heating temperature can be, to ensure better achievement of fine grain size. That is, the heating temperature of forging the billet into a flat billet is greater than the heating temperature of forging the flat billet into a stepped billet; the heating temperature of forging the flat billet into a stepped billet is greater than the heating temperature of forging the stepped billet into a forging. Specifically, for the austenitic stainless steel of this application, the temperature control at each stage is as follows: when forging the billet into a flat billet, the billet heating temperature is 1150~1230℃;

[0058] When a flat billet is forged into a stepped billet, the heating temperature of the flat billet is 1100~1150℃;

[0059] When forging stepped billets into forgings, the heating temperature of the stepped billets is 1100~1150℃.

[0060] In addition, the forging temperature for the final forging of the billet into a flat billet is 1150±20℃.

[0061] Forging Figure 1 and2 The forgings shown are made by remelting electroslag ingots, inspecting and cleaning surface cracks, and heating the electroslag ingots to 1150–1230°C according to a specific heating curve. After thorough heating, the ingots are removed from the furnace and forged into clamps. Figure 2 As shown. Flat billets can usually be forged using both upper and lower flat anvils. In this embodiment, the billet is heated to 1150–1230°C, held for a sufficient time, and then subjected to multiple upsetting and drawing processes using both upper and lower flat anvils to forge a flat square billet. The final drawing process for the flat square billet involves lowering the forging temperature to 1150±20°C. The resulting flat square billet is shown below. Figure 4 and 5 As shown.

[0062] Forging the billet into a flat billet can be done using upper and lower flat anvils. However, the subsequent forging is difficult to achieve using existing forging fixtures. Therefore, this application also provides a corresponding forming device, which includes a first forging assembly and a second forging assembly.

[0063] A first forging assembly is used to forge a flat billet into the stepped billet. The first forging assembly includes a first upper flat anvil and a first anvil 1. The first anvil 1 has a first concave cavity 16 in the middle. The first anvil 1 has a material-separating section and a drawing section arranged sequentially along the first concave cavity 16. The material-separating section has outwardly convex material-separating angles 13 on both sides of the first concave cavity. The material-separating angles 13 form a first plane 15 on the side away from the first concave cavity 16. The drawing section forms a second plane 11 on both sides of the first concave cavity. The height of the first plane 15 is lower than the height of the second plane 11.

[0064] When forging a flat billet into a stepped billet, the flat billet is placed on the dividing section from one side of the dividing section of the first forging assembly. The flat billet is laterally divided by pressing down with the first upper flat anvil. The flat billet is moved so that the divided section moves to the elongation section of the first anvil and the undivided section moves to the dividing section of the first anvil. The division and elongation are continued by pressing down with the first upper flat anvil. The movement, division and elongation are repeated until the billet is completely divided and elongated, forming a stepped billet with a raised structure on the first side.

[0065] In this stage, the flat billet is heated to 1100–1150℃, and the first forging assembly is used to forge the flat billet to achieve transverse material separation and longitudinal elongation. A common flat anvil can be used for the first upper flat anvil; the width of the first type anvil can usually be the same as that of the first upper flat anvil, such as… Figure 6 and 7As shown, the first anvil 1 has a first concave cavity 16 in the middle. The first anvil is divided into two sections. One section has a convex parting angle 13, with a first plane 15 formed on the side of the parting angle 13. The top of the parting angle 13 has an edge 12, and the outer side has a gentle slope structure 14. The other section has second planes 11 on both sides. The height of the first plane is lower than the height of the second plane to achieve elongation while parting the material. Forging schematic diagram is shown below. Figure 8 and 9 As shown, ① During forging, the first upper flat anvil and the first type anvil can be preheated to a temperature of 200-300℃; ② The first type anvil is installed on the lower platform of the press, aligned with the first upper flat anvil installed on the press in the left, right, front and back directions; ③ Lubricant is sprayed onto the upper surface of the first type anvil and the lower surface of the first upper flat anvil; ④ After the manipulator clamps the billet out of the furnace, it feeds from one side of the material distribution section of the first type anvil 1 and places it on the material distribution angle 13, aligned in the width direction; ⑤ The first upper flat anvil presses down the billet, and the material distribution angle 13 divides the billet laterally; the manipulator clamps and lifts the divided billet and moves it further to the second plane 11; ⑦ Repeat steps ④ to ⑥ until the length direction is completed and the billet is horizontally forged into a stepped billet with parts I, II and III.

[0066] The stepped billet is forged into a final forging using a second forging assembly. The second forging assembly includes a second upper anvil 2 and a second lower anvil 3. The second upper anvil 2 is provided with an outward protrusion adapted to the concave structure of the forging, and the second lower anvil 3 is provided with a second inner concave cavity adapted to the protruding structure of the forging. The protruding structure of the stepped billet is aligned with the second inner concave cavity and placed on the second lower anvil 3. The second upper anvil 2 is used to press down and forge the final forging.

[0067] As mentioned earlier, when forging the stepped billet into the final forging, it is preferable to forge it in two stages. However, if different forging methods are used for the two stages, two sets of forging components are required. In practice, the differences between the two forging stages are not significant. Therefore, in the preferred embodiment of this application, during the first forging stage, a backing plate 4 is placed in the second concave cavity of the second forging component. The protruding structure of the stepped billet is aligned with the second concave cavity and placed on the second lower anvil 3, and then pressed down by the second upper anvil 2 for forging. During the second forging stage, the backing plate 4 in the second concave cavity is removed, and the protruding structure of the stepped billet is aligned with the second concave cavity and placed on the second lower anvil 3, and then pressed down by the second upper anvil 2 forging to form the final forging. In this way, both stages of forging can be completed using a single forging component.

[0068] In the first forging stage, the stepped billet is heated to 1100–1150℃, and a second upper anvil, a second lower anvil, and a backing plate are used to achieve simultaneous deformation of sections I, II, and III of the billet. The second upper anvil and the second lower anvil are as follows: Figure 10 and Figure 11As shown, the convex part of the second upper anvil is adapted to the concave structure of the forging. The top of the convex part has a third plane 21, and the two sides of the convex part are fourth planes 23 adapted to the two sides of the top surface of the forging. The third plane 21 and the fourth plane 23 are transitioned by a side slope 22. The middle part of the second lower anvil has a second concave cavity adapted to the protruding structure of the forging. The two sides of the second concave cavity are inclined cavity walls 33, and the two sides of the second lower anvil are fifth planes 31. The fifth plane 31 and the cavity walls 33 are transitioned by a rounded corner 32. The second concave cavity is equipped with a pad 4 for the first forging. The pad 4 can be disassembled and installed according to different working needs. The forging method at this stage is as follows: ① The pad 4 is installed in the second inner cavity of the second lower anvil 3 and heated to 200-300℃ together with the second upper anvil 2; ② The second upper anvil 2 is installed on the upper crossbeam of the press to achieve up and down movement, and the second lower anvil 3 is fixed on the lower platform, aligned with the second upper anvil 2 in all directions; ③ Lubricant is sprayed onto the lower surface of the second upper anvil 2, the upper surface of the second lower anvil 3, and the pad 4; ④ After the billet is clamped by the manipulator and exits the furnace, one end is placed on the second lower anvil 3, and the amount of billet fed into the anvil can be adjusted according to the press pressure; ⑤ The second upper anvil 2 is pressed down, and interacts with the second lower anvil 3 and the pad 4 to compress the billet; ⑥ The manipulator clamps the billet and repeats steps ④ and ⑤ to finally forge the billet into... Figure 14 and 15 The structure shown.

[0069] The forging billet is heated to 1100-1150℃ for the second forging, and forging is performed using the second upper anvil 2 and the second lower anvil 3. Figure 16 and Figure 17 As shown. In this step, shim 4 is not used, leaving part II suspended to reduce the load during billet forging. Parts I and III are forged first, followed by part II, using the same method as the first forging. The first and second forging processes are repeated until the final forging is achieved. Figure 2 The forging shown.

Claims

1. A method for forming a transversely variable cross-section austenitic stainless steel forging, wherein a first side of the forging has a raised structure, a second side of the forging has a concave structure corresponding to the position of the raised structure, and the second side of the forging is the surface opposite to the first side, characterized in that... The method for forming transversely variable cross-section austenitic stainless steel forgings includes the following steps: The billet is forged into a flat billet, the sides of which form opposing first and second sides; A stepped billet is formed by forging a protruding structure on the first side by forging the two sides of the protruding structure corresponding to the forging on the flat billet. On the second side of the stepped blank, the corresponding position of the protruding structure is forged to form an inner concave structure, and then further deformed as a whole to form the final forging. The deformation amount of a billet forged into a flat billet is greater than the deformation amount of a flat billet forged into a stepped billet. The deformation amount of a flat billet forged into a stepped billet is greater than the deformation amount of a stepped billet forged into a forging. The heating temperature for forging a billet into a flat billet is higher than the heating temperature for forging a flat billet into a stepped billet; the heating temperature for forging a flat billet into a stepped billet is higher than the heating temperature forging a stepped billet into a forging. When the billet is forged into a flat billet, the heating temperature of the billet is 1150~1230℃; When a flat billet is forged into a stepped billet, the heating temperature of the flat billet is 1100~1150℃; When forging stepped billets into forgings, the heating temperature of the stepped billets is 1100~1150℃; The final forging temperature for forging the billet into a flat billet is 1150±20℃; A first forging assembly is used to forge a flat billet into the stepped billet. The first forging assembly includes a first upper flat anvil and a first shaped anvil. A first concave cavity is provided in the middle of the first shaped anvil. A material-separating section and a drawing section are sequentially provided along the first concave cavity of the first shaped anvil. The material-separating section is provided with outwardly convex material-separating angles on both sides of the first concave cavity. The material-separating angles form a first plane on the side away from the first concave cavity. The drawing section forms a second plane on both sides of the first concave cavity. The height of the first plane is lower than the height of the second plane. When forging a flat billet into a stepped billet, the flat billet is placed on the dividing section from one side of the dividing section of the first forging assembly. The flat billet is laterally divided by pressing down with the first upper flat anvil. The flat billet is moved so that the divided section moves to the elongation section of the first anvil and the undivided section moves to the dividing section of the first anvil. The division and elongation are continued by pressing down with the first upper flat anvil. The movement, division and elongation are repeated until the billet is completely divided and elongated, forming a stepped billet with a raised structure on the first side.

2. The method for forming transversely variable cross-section austenitic stainless steel forgings as described in claim 1, characterized in that: When forming the shape of the second side with a concave structure, the height of the convex structure formed on the first side is increased.

3. The method for forming transversely variable cross-section austenitic stainless steel forgings as described in claim 2, characterized in that: When forging the stepped billet into the final forging, it is forged in two stages; During the first forging process, a second side profile with a concave structure is formed. The height of the raised structure in the forging is further increased during the second forming process.

4. The method for forming transversely variable cross-section austenitic stainless steel forgings as described in claim 1, characterized in that: The stepped billet is forged into a final forging using a second forging assembly. The second forging assembly includes a second upper anvil and a second lower anvil. The second upper anvil is provided with an outward protrusion adapted to the concave structure of the forging, and the second lower anvil is provided with a second concave cavity adapted to the protruding structure of the forging. The raised structure of the stepped blank is aligned with the second concave cavity and placed on the second lower anvil. The final forging is forged by pressing down with the second upper anvil.

5. The method for forming transversely variable cross-section austenitic stainless steel forgings as described in claim 4, characterized in that: When forging the stepped billet into the final forging, it is forged in two stages; During the first forging process, a pad is placed in the second concave cavity of the second forging assembly. The raised structure of the stepped billet is aligned with the second concave cavity and placed on the second lower anvil. The forging is then performed by pressing down on the second upper anvil. During the second forging process, the pad in the second concave cavity is removed. The raised structure of the stepped blank is aligned with the second concave cavity and placed on the second lower anvil. The second upper anvil is used to press down and forge the blank to form the final forging.

Images