Control method for homogenization of IN718PLUS nickel-based alloy forgings

Abstract

This invention relates to the field of metal heat treatment technology, specifically to a method for controlling the homogenization of the microstructure of IN718PLUS nickel-based alloy forgings. The method involves: pre-rolling a ring forging to obtain a pre-rolled ring forging; annealing the pre-rolled ring forging to obtain an annealed ring forging; and final rolling the annealed ring forging to obtain a final rolled ring forging. The annealing process includes heating, holding, and cooling. After annealing, the proportion of grains of the same size grade in the ring forging is greater than 70%, and the grains of the ring forging are equiaxed. This solves the problem of deviations in the mechanical properties of existing IN718PLUS forgings.

Description

Technical Field

[0001] This invention relates to the field of metal heat treatment technology, and more specifically, to a method for controlling the homogenization of the microstructure of IN718PLUS nickel-based alloy forgings. Background Technology

[0002] IN718PLUS nickel-based alloy is a new type of nickel-based high-temperature alloy. Due to the inhomogeneity of raw materials during the forging process, and the uneven deformation and stress during the forging process, the metallographic structure of the alloy is also prone to inhomogeneity after the forging and heat treatment stages. This can lead to deviations in the mechanical properties of the forgings, or even unqualified products, resulting in poor consistency of product structure and properties and a lower pass rate. Summary of the Invention

[0003] To address the issue of deviations in the mechanical properties of IN718PLUS forgings, this invention provides a method for controlling the homogenization of the microstructure of IN718PLUS nickel-based alloy forgings.

[0004] In a first aspect, the present invention provides a method for controlling the homogenization of the microstructure of IN718PLUS nickel-based alloy forgings, comprising:

[0005] Pre-rolling: The ring forging is pre-rolled to obtain a pre-rolled ring forging.

[0006] Annealing: Annealing is performed on the pre-rolled annular forging to obtain the annealed annular forging.

[0007] Final rolling: The annealed annular forging is subjected to final rolling treatment to obtain the final rolled annular forging.

[0008] The annealing process includes the following steps:

[0009] Heating: The annular forging is placed in a heating furnace. The furnace is heated until the δ-phase grains in the annular forging begin to dissolve. Heating is then stopped. The temperature at which the δ-phase grains dissolve is K1.

[0010] The ring forging is kept at a temperature of K2 based on the temperature at which the δ phase grains begin to dissolve, K1, until the δ phase grains are completely dissolved, wherein K1+5℃≤K2≤K1+15℃.

[0011] Cool down and remove the annular forging from the heating furnace. The annular forging is then air-cooled. When the temperature of the annular forging is below K1, the δ phase grains in the annular forging begin to precipitate along the grain boundaries until the energy that causes the grain precipitation disappears, or the precipitation of the grain at the first position is hindered by the spatial steric hindrance of the grain at the second position, and the grain at the second position prevents the grain at the first position from continuing to precipitate.

[0012] Among them, the grains of the ring forging after final rolling have a grain size of more than 70% of the same grade, and the grains of the ring forging after annealing are equiaxed grains.

[0013] In some embodiments, the temperature K1 at which the grains dissolve is 1000℃-1040℃.

[0014] In some embodiments, the heat preservation time is 120 min to 180 min.

[0015] In some embodiments, the heat preservation time is calculated as 0.5 min / mm × effective wall thickness, where the effective wall thickness is the effective cross-sectional thickness of the annular forging.

[0016] In some embodiments, the grain size distribution of the annealed annular forging has a grade difference of 1 to 2.

[0017] In some embodiments, when the grain size difference is 1 level, the grain size of the first level accounts for 75% to 85%, and the grain size of the second level accounts for 10% to 25%.

[0018] In some embodiments, when the grain size difference is 2 levels, the first level of grain size accounts for 70%-80%, the second level of grain size accounts for 15%-20%, and the third level of grain size accounts for 5%-10%.

[0019] In some embodiments, the final rolling includes an expansion amount of 10%-20% for the annular forging.

[0020] In some embodiments, the cooling temperature is 870°C-950°C.

[0021] To address the issue of deviations in the mechanical properties of IN718PLUS forgings, this invention offers the following advantages:

[0022] Methods for controlling the homogenization of the microstructure of nickel-based alloy forgings may include: pre-rolling, where a ring forging is pre-rolled to obtain a pre-rolled ring forging; annealing, where the pre-rolled ring forging is annealed to obtain an annealed ring forging; and final rolling, where the annealed ring forging is final-rolled to obtain a final-rolled ring forging. The annealing process includes: heating, where the ring forging is placed in a heating furnace, and the furnace temperature is raised to the point where the δ-phase grains in the ring forging begin to dissolve, then the heating is stopped, and the temperature at which the δ-phase grains dissolve is K1; and holding, where, based on the temperature K1 at which the δ-phase grains begin to dissolve, the ring forging is held at a temperature of K2 until the δ-phase grains are completely dissolved, wherein K1+5℃≤K2≤K1+15℃. After cooling, the annular forging is removed from the heating furnace and air-cooled. When the temperature of the annular forging is below K1, δ-phase grains begin to precipitate along the grain boundaries until the energy causing grain precipitation disappears, or the precipitation of grains at the first position is hindered by the steric hindrance of grains at the second position, preventing further precipitation of grains at the first position. By annealing the pre-rolled annular forging, the grains within the annular forging are refined through three steps: heating, holding, and cooling. This ensures that the proportion of grains of the same grade is greater than 70%, effectively improving the uniformity of the metallographic structure of the IN718PLUS nickel-based alloy, thereby avoiding stress concentration, improving the mechanical properties of the forging, and increasing the product qualification rate. Attached Figure Description

[0023] Figure 1 A flowchart is shown below illustrating the method for controlling the homogenization of the microstructure of IN718PLUS nickel-based alloy forgings provided by this invention.

[0024] Figure 2 The present invention provides a temperature curve of the annealing process of an IN718PLUS nickel-based alloy forging.

[0025] Figure 3 The metallographic structure of an IN718PLUS nickel-based alloy forging after pre-rolling is shown in the figure provided by the present invention.

[0026] Figure 4 The metallographic structure of an IN718PLUS nickel-based alloy forging provided by the present invention after annealing is shown. Detailed Implementation

[0027] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, and are not intended to imply any limitation on the scope of the disclosure.

[0028] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment". The term "another embodiment" is to be interpreted as "at least one other embodiment".

[0029] This embodiment discloses a method for controlling the homogenization of the microstructure of IN718PLUS nickel-based alloy forgings, such as... Figure 1 As shown, it may include:

[0030] Step S101, pre-rolling: The annular forging is pre-rolled to obtain a pre-rolled annular forging.

[0031] In this embodiment, the forging is rough-machined by pre-rolling so that the approximate dimensions of the forging are similar to those of the finished forging.

[0032] Step S102, Annealing: Anneal the pre-rolled annular forging to obtain the annealed annular forging.

[0033] In this embodiment, annealing can reduce the hardness of the forging, refine the grains, make the material composition more uniform, reduce residual stress, and facilitate subsequent processing.

[0034] Step S103, final rolling: The annealed annular forging is subjected to final rolling treatment to obtain the final rolled annular forging.

[0035] In this embodiment, the forging is finished by final rolling to obtain a final rolled ring forging.

[0036] Optionally, the final rolling includes an expansion amount of 10%-20% for the ring forging.

[0037] By controlling the deformation of the forging during the final rolling process to 10%-20%, the δ phase in the forging microstructure can be re-precipitated along the grain boundaries. This ultimately results in uniform grain size and stable overall performance of the forging.

[0038] Preferably, the deformation of the final rolled ring forging can be 10%-15%.

[0039] Preferably, the deformation of the final rolled ring forging can be 15%-20%.

[0040] Preferably, the deformation of the final rolled ring forging can be 11%-19%.

[0041] like Figure 2 As shown, step S102 includes the following steps:

[0042] Step S102a: Heating. The annular forging is placed in a heating furnace. The furnace is heated until the δ-phase grains in the annular forging begin to dissolve. Heating is stopped. The temperature K1 for the solubility of the δ-phase grains is [not specified].

[0043] In this embodiment, heating the annular forging helps to dissolve the δ phase on the grain boundaries of the annular forging. The timing for stopping the heating can be determined based on the temperature K1 of the δ phase grain solubility. When the heating furnace heats up to above K1, the heating operation is stopped according to the actual situation.

[0044] Optionally, the grain dissolution temperature K1 is 1000℃-1040℃.

[0045] Among them, when the temperature reaches 1000℃-1040℃, the δ phase grains gradually dissolve.

[0046] Preferably, the temperature K1 for grain dissolution can be 1000℃-1010℃.

[0047] Preferably, the temperature K1 for grain dissolution can be 1010℃-1020℃.

[0048] Preferably, the temperature K1 for grain dissolution can be 1020℃-1030℃.

[0049] Preferably, the temperature K1 for grain dissolution can be 1030℃-1040℃.

[0050] Step S102b, heat preservation: Based on the temperature K1 at which the δ phase grains begin to dissolve, the annular forging is kept at a temperature of K2 until the δ phase grains are completely dissolved, wherein K1+5℃≤K2≤K1+15℃.

[0051] In this embodiment, by setting the furnace temperature K2 5-15°C above the δ phase grain dissolution temperature K1 and heating and holding it at that temperature, the δ phase grains can be dissolved more completely. The specific value of K2 is not limited and can be reasonably selected according to the actual application requirements.

[0052] Preferably, the temperature K2 can be in the range of K1+5℃≤K2≤K1+10℃.

[0053] Preferably, the temperature K2 can be in the range of K1+10℃≤K2≤K1+15℃.

[0054] Preferably, the temperature K2 can be in the range of K1+6℃≤K2≤K1+14℃.

[0055] Optional, the heat preservation time is 120min-180min.

[0056] By holding the forging at a certain temperature for a certain period of time, the δ phase grains in the forging material can be fully dissolved. The specific holding time is not limited and can be reasonably selected according to the actual application requirements.

[0057] In some embodiments, the heat preservation time is calculated as 0.5 min / mm × effective wall thickness, where the effective wall thickness is the effective cross-sectional thickness of the annular forging.

[0058] The heat preservation time is calculated based on 0.5 min / mm × effective wall thickness, and the effective wall thickness is determined by the structure of the ring forging itself.

[0059] Step S102c: Cooling down, remove the annular forging from the heating furnace, and air-cool the annular forging. When the temperature of the annular forging is lower than K1, the δ phase grains in the annular forging begin to precipitate along the grain boundaries until the energy that causes the grain precipitation disappears, or the precipitation of the grain at the first position is hindered by the spatial steric hindrance of the grain at the second position, and the grain at the second position prevents the grain at the first position from continuing to precipitate.

[0060] In this embodiment, after the heat preservation step is completed, the annular forging is removed from the heating furnace and air-cooled. At this time, the δ phase grains in the annular forging begin to precipitate along the grain boundaries. The precipitated δ phase grains are more uniform than the δ phase grains before annealing. This continues until the energy that caused the grain precipitation disappears, or the precipitation of the grain at the first position is hindered by the spatial steric hindrance of the grain at the second position. The grain at the second position prevents the grain at the first position from continuing to precipitate. At this time, the annealing stage ends, and the annealed annular forging is obtained.

[0061] Optionally, the cooling temperature is 870℃-950℃.

[0062] Setting the cooling temperature to 870℃-950℃ ensures that δ-phase grains precipitate along the grain boundaries while avoiding the re-accumulation of internal stress within the material due to excessive temperature difference.

[0063] Preferably, the cooling temperature can be 870℃-880℃.

[0064] Preferably, the cooling temperature can be 880℃-890℃.

[0065] Preferably, the cooling temperature can be 890℃-900℃.

[0066] Preferably, the cooling temperature can be 900℃-910℃.

[0067] Preferably, the cooling temperature can be 910℃-920℃.

[0068] Preferably, the cooling temperature can be 920℃-930℃.

[0069] Preferably, the cooling temperature can be 930℃-940℃.

[0070] Preferably, the cooling temperature can be 940℃-950℃.

[0071] Among them, the grains of the ring forging after final rolling have a grain size of more than 70% of the same grade, and the grains of the ring forging after annealing are equiaxed grains.

[0072] In this embodiment, the grains of the annular forging after annealing are all equiaxed grains, and the proportion of grains of the same grade is greater than 70%. Compared with the annular forging before the annealing step, the grains are more uniform, which can effectively ensure the consistency of the overall mechanical properties of the annular forging and improve the qualification rate of the finished annular forging.

[0073] Optionally, the grain size distribution of the annealed ring forging has a grade difference of 1 to 2.

[0074] By controlling the grain size difference to 1 to 2 levels, the grains of the annealed ring forging can be more uniform, thus avoiding stress concentration.

[0075] Furthermore, when the grain size difference is 1 level, the first level of grain size accounts for 75% to 85%, and the second level of grain size accounts for 10% to 25%.

[0076] By limiting the proportion of the first-grade grain size to 75%–85% and the proportion of the second-grade grain size to 10%–25%, the consistency of the grain size in the ring forging can be ensured, and stress concentration caused by inconsistent grain size can be avoided.

[0077] Furthermore, when the grain size difference is 1 level, the proportion of the first level of grain size can be 75% to 80%, and the proportion of the second level of grain size can be 20% to 25%.

[0078] Furthermore, when the grain size difference is 1 level, the proportion of the first level of grain size can be 80% to 85%, and the proportion of the second level of grain size can be 15% to 20%.

[0079] Furthermore, when the grain size difference is 1 level, the proportion of the first level of grain size can be 76% to 84%, and the proportion of the second level of grain size is 16% to 24%.

[0080] Furthermore, when the grain size difference is 2 levels, the first level of grain size accounts for 70%-80%, the second level of grain size accounts for 15%-20%, and the third level of grain size accounts for 5%-10%.

[0081] By limiting the proportion of the first-grade grain size to 70%-80%, the second-grade grain size to 15%-20%, and the third-grade grain size to 5%-10%, the consistency of the grain size in the ring forging can be ensured, and stress concentration caused by inconsistent grain size can be avoided.

[0082] Furthermore, when the grain size difference is 2 levels, the first level of grain size can account for 70%-75%, the second level of grain size can account for 15%-20%, and the third level of grain size can account for 5%-10%.

[0083] Furthermore, when the grain size difference is 2 levels, the first level of grain size can account for 75%-80%, the second level of grain size can account for 15%-20%, and the third level of grain size can account for 5%-10%.

[0084] Furthermore, when the grain size difference is 2 levels, the first level of grain size can account for 75%-85%, the second level of grain size can account for 16%-19%, and the third level of grain size can account for 6%-9%.

[0085] As can be seen from the above description of this embodiment, the method for controlling the homogenization of the microstructure of IN718PLUS nickel-based alloy forgings disclosed in this embodiment may include: pre-rolling, pre-rolling the ring forging to obtain a pre-rolled ring forging; annealing, annealing the pre-rolled ring forging to obtain an annealed ring forging; and final rolling, final rolling the annealed ring forging to obtain a final rolled ring forging. The annealing process includes: heating, placing the ring forging in a heating furnace, heating the furnace to the point where the δ-phase grains in the ring forging begin to dissolve, stopping the heating, and setting the temperature K1 for the solubility of the δ-phase grains; and holding, based on the temperature K1 at which the δ-phase grains begin to dissolve, holding the ring forging at a temperature K2 until the δ-phase grains are completely dissolved, wherein K1+5℃≤K2≤K1+15℃. The ring forging is cooled and removed from the heating furnace. It undergoes air cooling. When the temperature of the ring forging is below K1, δ-phase grains begin to precipitate along grain boundaries until the energy causing grain precipitation disappears, or the precipitation of grains at the first position is hindered by the steric hindrance of grains at the second position, preventing further precipitation of grains at the first position. Figure 3 and Figure 4As shown, the method for controlling the uniformity of the microstructure of IN718PLUS nickel-based alloy forgings provided in this application involves annealing the pre-rolled ring forgings and using three steps—heating, holding, and cooling—to fully refine the grains within the ring forgings, ensuring that the proportion of grains of the same grade is greater than 70%. This effectively improves the uniformity of the metallographic structure of the IN718PLUS nickel-based alloy, thereby avoiding stress concentration, improving the mechanical properties of the forgings, and increasing the product qualification rate.

[0086] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes can be made in form and detail without departing from the spirit and scope of this disclosure.

Claims

1. A method for controlling the homogeneity of microstructure in IN718PLUS nickel-based alloy forgings, characterized in that, Pre-rolling: The ring forging is pre-rolled to obtain a pre-rolled ring forging. Annealing: Annealing is performed on the pre-rolled annular forging to obtain the annealed annular forging. Final rolling: The annealed annular forging is subjected to final rolling treatment to obtain the final rolled annular forging. The annealing process includes the following steps: Heating: The annular forging is placed in a heating furnace. The furnace is heated until the δ-phase grains in the annular forging begin to dissolve. Heating is then stopped. The temperature at which the δ-phase grains begin to dissolve is K1. The ring forging is kept at a temperature of K2 based on the temperature at which the δ phase grains begin to dissolve, K1, until the δ phase grains are completely dissolved, wherein K1+5℃≤K2≤K1+15℃. Cool down and remove the annular forging from the heating furnace. The annular forging is then air-cooled. When the temperature of the annular forging is below K1, the δ phase grains in the annular forging begin to precipitate along the grain boundaries until the energy that causes the grain precipitation disappears, or the precipitation of the grain at the first position is hindered by the spatial steric hindrance of the grain at the second position, and the grain at the second position prevents the grain at the first position from continuing to precipitate. Among them, the grains of the annular forging after final rolling have a grain size of the same grade accounting for more than 70%, and the grains of the annular forging after annealing are equiaxed grains. The heat preservation time is calculated based on 0.5 min / mm × effective wall thickness, where the effective wall thickness is the effective cross-sectional thickness of the annular forging. The grain size distribution of the annealed annular forging has a grade difference of 1 to 2. When the grain size difference is 1 level, the grain size of the first level accounts for 75%~85%, and the grain size of the second level accounts for 10%-25%. The final rolling process includes an expansion amount of 10%-20% for the annular forging.

2. The control method of IN718PLUS nickel-base alloy forge piece microstructure homogenization according to claim 1, characterized in that, The temperature K1 at which the grains dissolve is 1000℃-1040℃.

3. The control method of IN718PLUS nickel-base alloy forge piece microstructure homogenization according to claim 1, characterized in that, The heat preservation time is 120-180 minutes.

4. The method for controlling the homogenization of the microstructure of IN718PLUS nickel-based alloy forgings according to claim 1, characterized in that, When the grain size difference is 2 levels, the first level of grain size accounts for 70%-80%, the second level of grain size accounts for 15%-20%, and the third level of grain size accounts for 5%-10%.

5. The method for controlling the homogenization of the microstructure of IN718PLUS nickel-based alloy forgings according to claim 1, characterized in that, The cooling temperature is 870℃-950℃.

Images