CN111496160B

CN111496160B - Forging method for improving end surface structure of high-temperature alloy ingot blank, application of forging method and high-temperature alloy forging blank

Info

Publication number: CN111496160B
Application number: CN202010350792.0A
Authority: CN
Inventors: 付锐; 李福林; 孟令超; 尹法杰; 杜金辉; 冯滌
Original assignee: Central Iron and Steel Research Institute; Gaona Aero Material Co Ltd
Current assignee: Central Iron and Steel Research Institute; Gaona Aero Material Co Ltd
Priority date: 2020-04-28
Filing date: 2020-04-28
Publication date: 2021-12-21
Anticipated expiration: 2040-04-28
Also published as: CN111496160A

Abstract

The invention provides a forging method for improving the end surface structure of a high-temperature alloy ingot blank, application thereof and a high-temperature alloy forging blank, which relate to the field of hot working forging and comprise the following steps: a) arranging a first hard covering mould at the first end of the high-temperature alloy ingot blank, and arranging a second hard covering mould at the second end of the high-temperature alloy ingot blank to obtain a blank with a hard covering; b) upsetting the blank with the hard sheath to obtain an upset ingot blank; c) sequentially carrying out upsetting shaping and annealing treatment on the upset ingot blank without the hard sheath, wherein a gap is formed between the surface of the first hard sheath die and the surface of the second hard sheath die, which face the high-temperature alloy ingot blank, and the thickness of the gap in the radial direction of the high-temperature alloy ingot blank is gradually increased from the center to the periphery; the first hard cover die and the second hard cover die are made of the same material as the high-temperature alloy ingot blank.

Description

Forging method for improving end surface structure of high-temperature alloy ingot blank, application of forging method and high-temperature alloy forging blank

Technical Field

The invention relates to the technical field of hot working forging, in particular to a forging method for improving the end surface structure of a high-temperature alloy ingot blank, application of the forging method and the high-temperature alloy forging blank.

Background

Upsetting is the most common operation in the alloy forging process, firstly to achieve the shape and size requirements of the product, and secondly to further improve the internal microstructure of the alloy. The minimum deformation and the fastest cooling in the upsetting process are the upper end surface and the lower end surface of the ingot blank which are contacted with the hammer anvil, and the difference of the structures is larger than that of other parts, so that the difference is reduced to the maximum extent to meet the requirement of certain alloys on higher structure uniformity.

For high-temperature alloy ingots, such as high-aspect-ratio (the aspect ratio is up to 5) hard-deformation high-temperature alloy ingots which are prepared by adopting an electroslag remelting continuous directional solidification smelting process in order to meet the comprehensive requirements of low segregation and product size and weight, upsetting is the only means for cogging and forging. The large height-diameter ratio is the fastest to lower the temperature of the upper and lower end parts of the high temperature alloy ingot blank contacting the hammer anvil of the forging press in the upsetting process, and the metal flow of the end part contacting the hammer anvil is the least (the minimum deformation), so that the end part leaves columnar crystal structures with large as-cast thickness in the upsetting process for 2-3 times and is embedded into the ingot blank for a certain depth, and the columnar crystal structures are difficult to eliminate in the follow-up process.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

The invention aims to provide a forging method for improving the end surface structure of a high-temperature alloy ingot blank, which can realize the purpose of improving the microstructure of the end surface of the high-temperature alloy ingot blank with a large height-diameter ratio after upsetting and cogging.

The invention provides a forging method for improving the end surface structure of a high-temperature alloy ingot blank, which comprises the following steps:

a) arranging a first hard covering mould at the first end of the high-temperature alloy ingot blank, and arranging a second hard covering mould at the second end of the high-temperature alloy ingot blank to obtain a blank with a hard covering;

b) upsetting the blank with the hard sheath to obtain an upset ingot blank;

c) the ingot blank after upsetting of the hard sheath is removed is sequentially subjected to upsetting shaping and annealing treatment,

wherein the first end and the second end are oppositely arranged along the axial direction of the high-temperature alloy ingot blank;

a gap is formed between the surface of the first hard cover die and the surface of the second hard cover die, which face the high-temperature alloy ingot blank, and the thickness of the gap in the radial direction of the high-temperature alloy ingot blank is gradually increased from the center to the periphery;

the first hard cover die and the second hard cover die are made of the same material as the high-temperature alloy ingot blank.

Further, the thickness of the first hard cover die and the second hard cover die is 15-30mm respectively and independently along the axial direction of the high-temperature alloy ingot blank;

preferably, the first and second hard jacket molds are rounded at right angles to the side facing the superalloy ingot blank, preferably rounded R5-10.

Further, a soft sheath is arranged in the gap;

preferably, the soft cover comprises a glass fiber blanket and/or glass powder.

Further, welding the first hard cover die and the second hard cover die with the high-temperature alloy ingot blank by adopting an argon arc welding mode;

preferably, a nickel-chromium welding wire material is adopted as a welding wire during argon arc welding;

preferably, the tolerances of cylindricity, parallelism and coaxiality of the welded blank with the hard sheath are each independently within ± 2 mm.

Further, in the step b), firstly, the blank with the hard sheath is subjected to heat preservation at 1050 ℃ for 0.5-1.5h, then at 1170 ℃ of 1100 ℃ for 2-4h, and then the blank with the hard sheath is subjected to upsetting treatment;

preferably, the blank with the hard sheath is firstly insulated for 0.5-1.5h at 1050 ℃ and then for 2-4h at 1170 ℃ of 1000 ℃, then the soft sheath is wrapped on the surface of the blank with the hard sheath, and finally the blank wrapped with the soft sheath is subjected to upsetting treatment;

preferably, after the surface of the blank with the hard sheath is coated with the soft sheath, the blank is subjected to heat preservation at the temperature of 1100-1170 ℃ for 0.5-1.5h, and then the blank coated with the soft sheath is subjected to upsetting treatment;

preferably, in step b), the deformation rate of the upsetting process is 10-20mm/s, and/or the deformation amount of the upsetting process is 20-50%.

Further, in step c), the deformation amount of the upsetting shaping is more than 0 and 10% or less;

preferably, the temperature of the annealing treatment is 1100-1200 ℃;

preferably, steps a) to c) are repeated 2-4 times.

Further, prior to step a), subjecting the superalloy ingot to a homogenization heat treatment;

preferably, the homogenization heat treatment comprises: the high-temperature alloy ingot blank is firstly subjected to heat preservation at the temperature of 400-850 ℃ for not less than 2h, then is subjected to heat preservation at the temperature of 1050-1100 ℃ for not less than 4h, then is subjected to heat preservation at the temperature of 1140-1180 ℃ for not less than 4h, and finally is subjected to heat preservation at the temperature of 1180-1210 ℃ for not less than 24 h.

Further, the superalloy comprises at least one of a nickel-based superalloy, an iron-nickel-based superalloy, and a cobalt-based superalloy;

preferably, the high temperature alloy has an aspect ratio of 3 to 5;

preferably, the superalloy comprises a composition having the following mass fractions: co: 13.0-21.0%, Cr: 12 to 16 percent; mo: 3.5-4.5%, W: 2.0-4.0%, Al: 1.9-3.5%, Ti: 3.5 to 4.5 percent; nb: 0.5-1.5%; ta: 0.0 to 3.0 percent; b: 0.010-0.040%; c: 0.005-0.060%; zr: 0.030-0.060%; fe: 0 to 0.5 percent; and the balance being Ni;

preferably, the superalloy comprises a GH4096 alloy.

Use of a forging method as described above for the preparation of a superalloy forging stock.

A high-temperature alloy forging stock adopts the forging method in the process of preparing the high-temperature alloy forging stock.

Compared with the prior art, the invention can at least obtain the following beneficial effects:

the forging method can effectively improve the microstructure state of the surface core parts of the upper end and the lower end (namely the first end and the second end) of the high-temperature alloy ingot blank, improve the surface quality of the end surface, reduce the risk of cracking of the end surface and achieve the effect of reducing the structure difference of the end surface core parts and other parts; the annealing treatment adopted after the upsetting and shaping in the step c) is an effective means for generating the sub-dynamic recrystallization to improve the structure, and can improve the dynamic recrystallization which is not generated in time in the forging process to a great extent; the hard cover die is made of the same alloy material as the high-temperature alloy ingot blank, so that the pressure applied to the end face is greatly increased, and the coordination between the deformation of the hard cover die material and the forging blank is effectively ensured; in addition, the forging method can also improve the utilization rate of the high-temperature alloy ingot blank material, reduce the material cost and save the national strategic resources.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1a is a schematic diagram of a blank with a hard wrap in accordance with an embodiment of the present invention;

FIG. 1b is a schematic illustration of a blank with a hard wrap in accordance with an embodiment of the present invention;

FIG. 2 is a schematic structural view of an upset superalloy ingot with the hard sheath removed in accordance with one embodiment of the present invention;

FIG. 3 is a schematic structural view of an upset-shaped superalloy ingot in accordance with one embodiment of the present invention;

FIG. 4 is a scanning electron micrograph of the microstructure of an ingot of superalloy forged in example 1;

FIG. 5 is a scanning electron micrograph of the microstructure of an ingot of the superalloy forged in comparative example 1;

FIG. 6 is a scanning electron micrograph of the microstructure of an ingot of the superalloy forged in comparative example 2.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

In one aspect of the present invention, the present invention provides a forging method for improving an end surface structure of a superalloy ingot blank, referring to fig. 1a and 1b, the forging method comprising:

s100: arranging a first hard covering die 200 at a first end 110 of the high-temperature alloy ingot blank 100, and arranging a second hard covering die 300 at a second end 120 of the high-temperature alloy ingot blank 100 to obtain a blank with a hard covering;

wherein the first end 110 and the second end 120 are oppositely disposed along an axial direction of the superalloy ingot 100; a gap 400 is arranged between the surface of the first hard pack die 200 and the second hard pack die 300 facing the superalloy ingot 100 and the superalloy ingot 100, and the thickness of the gap 400 gradually increases from the center to the periphery along the radial direction of the superalloy ingot 100; the first hard cover die 200 and the second hard cover die 300 are made of the same material as the high-temperature alloy ingot blank 100.

The thickness of the gap is defined as the distance, in the axial direction of the superalloy ingot, between the first end surface of the superalloy ingot and the surface of the first hard cover mold facing the superalloy ingot, and between the second end surface of the superalloy ingot and the surface of the second hard cover mold facing the superalloy ingot.

In some embodiments of the present invention, the thickness of the first and second hard jacket molds is 15-30mm (e.g., may be 15mm, 20mm, 25mm, 30mm, etc.) in the axial direction of the superalloy ingot blank. Compared with the thickness range, the purpose of the invention can not be realized when the thicknesses of the first hard cover die and the second hard cover die are too large or too small, the first hard cover die and the second hard cover die are easy to fall off when the thicknesses are too large, and the purpose of increasing the end face deformation can not be realized when the thicknesses are too small.

In some embodiments of the invention, the first and second hard jacket molds are rounded, preferably R5-10, at right angles to the sides of the superalloy ingots facing the ingot. If the first hard covering die and the second hard covering die face one side of the high-temperature alloy ingot blank, the ingot blank is easily damaged due to the fact that the right angle is high in hardness, and the fillet can effectively avoid the problems.

In some embodiments of the invention, referring to fig. 1a and 1b, a sock 500 is disposed in the void; preferably, the soft cover comprises a glass fiber blanket (commercially available with a gauge thickness of 5mm) and/or glass powder. It is understood that, referring to fig. 1b, the portions of the first and second hard cover molds that are in direct contact with the high temperature embryonic ingot may also be separated by a soft cover to reduce the transfer of heat.

In some embodiments of the present invention, the first hard cover die and the second hard cover die are welded to the superalloy ingot blank by argon arc welding, and the welded seam 600 may refer to fig. 1a and 1 b; preferably, a nickel-chromium welding wire material is adopted as a welding wire during argon arc welding; preferably, the tolerances of cylindricity, parallelism and coaxiality of the welded blank with the hard sheath are each independently within ± 2 mm.

In some embodiments of the invention, the superalloy ingots are prepared by a vacuum induction and electroslag remelting continuous directional solidification smelting two-in-one process, or by a vacuum induction, electroslag remelting and vacuum consumable triple smelting process; the height-to-diameter ratio (i.e., height/diameter) of the superalloy ingot blank is 3-5.

In some embodiments of the invention, the superalloy comprises at least one of a nickel-based superalloy, an iron-nickel-based superalloy, and a cobalt-based superalloy. In some embodiments of the invention, the superalloy comprises a composition having the following mass fractions: co: 13.0-21.0%, Cr: 12 to 16 percent; mo: 3.5-4.5%, W: 2.0-4.0%, Al: 1.9-3.5%, Ti: 3.5 to 4.5 percent; nb: 0.5-1.5%; ta: 0.0 to 3.0 percent; b: 0.010-0.040%; c: 0.005-0.060%; zr: 0.030-0.060%; fe: 0 to 0.5 percent; and a balance of Ni, in some preferred embodiments of the invention, the superalloy comprises a GH4096 alloy.

In some embodiments of the present invention, prior to step S100, the superalloy ingot is subjected to a homogenization heat treatment; preferably, the homogenization heat treatment comprises: the high-temperature alloy ingot blank is firstly subjected to heat preservation at the temperature of 400-850 ℃ for not less than 2h, then is subjected to heat preservation at the temperature of 1050-1100 ℃ for not less than 4h, then is subjected to heat preservation at the temperature of 1140-1180 ℃ for not less than 4h, and finally is subjected to heat preservation at the temperature of 1180-1210 ℃ for not less than 24 h. In some embodiments of the invention, the homogenizing heat treatment comprises: heating to 850 ℃ along with the temperature rise of the furnace, keeping the temperature for not less than 2h, heating to 1050 ℃ along with the temperature rise of the furnace at the speed of not more than 80 ℃/h, keeping the temperature for not less than 4h, heating to 1140-1180 ℃ at the speed of not more than 10 ℃/h, keeping the temperature for not less than 4h, heating to a certain temperature between 1180-1210 ℃ at the speed of not more than 10 ℃/h, keeping the temperature for not less than 24h, cooling to 800 ℃ along with the furnace, and taking out of the furnace for air cooling.

S200: and upsetting the blank with the hard sheath to obtain an upset ingot blank.

In some embodiments of the present invention, in step S200, the blank with the hard sheath is first subjected to heat preservation at 1050 ℃ for 0.5-1.5h and then at 1170 ℃ for 2-4h, and then subjected to upsetting treatment.

In some preferred embodiments of the invention, the blank with the hard sheath is firstly insulated at 1050 ℃ for 0.5-1.5h, then at 1170 ℃ for 2-4h, then the surface of the blank with the hard sheath is wrapped with the soft sheath, and finally the blank wrapped with the soft sheath is subjected to upsetting treatment. Therefore, the soft sheath is coated on the surface of the blank with the hard sheath, so that the heat transfer speed between the forging anvil and the blank with the hard sheath can be reduced.

In some embodiments of the invention, after the surface of the blank with the hard sheath is coated with the soft sheath, the blank is subjected to heat preservation at the temperature of 1100-1170 ℃ for 0.5-1.5h, and then the blank coated with the soft sheath is subjected to upsetting treatment; the soft package sleeve adopts a high-temperature glass fiber blanket and glass powder.

In some embodiments of the present invention, in step S200, the deformation rate of the upsetting process is 10-20mm/S (e.g., 10mm/S, 15mm/S, or 20mm/S, etc.), and/or the deformation amount of the upsetting process is 20-50% (e.g., 20%, 30%, 40%, or 50%, etc.).

S300: and (4) sequentially carrying out upsetting shaping and annealing treatment on the upset ingot blank from which the hard sheath is removed.

In some embodiments of the present invention, the upset ingot from which the hard cap is removed may be removed by using a radial light rounding operation to separate the first and second hard cap dies from the superalloy ingot, as shown in fig. 2.

In some embodiments of the present invention, in step S300, the upset deformation is greater than 0 and less than or equal to 10% (e.g., may be 2%, 4%, 6%, 8%, 10%, etc.), and the upset shaped superalloy ingot may have a relatively regular first end surface and a relatively regular second end surface, as shown in fig. 3.

In some embodiments of the present invention, the annealing temperature is 1100-. The annealing heat treatment is carried out in the above temperature range in order to cause sub-dynamic recrystallization, which is the main purpose of grain refinement of the high-temperature alloy, and the recrystallization is classified into three types, static recrystallization, dynamic recrystallization, and sub-dynamic recrystallization, which means that during upsetting deformation, dynamic recrystallization nuclei that have been formed but have not grown yet, and recrystallized grains that have grown but are left midway, start to grow or start to migrate when annealing is carried out at a sufficiently high temperature after the deformation is terminated. However, the first and second end surfaces of the superalloy ingot are deformed to a relatively small extent and recrystallization has not yet occurred or ceased, and thus annealing heat treatment for sub-dynamic recrystallization is required to improve the texture.

In some embodiments of the invention, steps S100 to S3002-4 times are repeated.

It should be noted that repeating S100 to S3002 times means performing the flow from step S100 to step S300 twice; repeat 3-4 times and so on.

In some embodiments of the present invention, a forging method for improving an end surface structure of a superalloy ingot is described by repeating S100 to S3002, the forging method comprising the steps of:

1) arranging a first hard sheath die at the first end of the high-temperature alloy ingot blank, arranging a second hard sheath die at the second end of the high-temperature alloy ingot blank to obtain a blank with a hard sheath, placing the blank with the hard sheath in a heating furnace, keeping the temperature for 0.5-1.5h when the temperature of the blank with the hard sheath is raised to 1000-plus 1050 ℃, keeping the temperature for 2-4h when the temperature of the blank with the furnace is raised to 1100-plus 1170 ℃, taking out the blank from a furnace sheath, and then returning the blank to the furnace for keeping the temperature for 0.5-1.5 h;

2) placing the blank obtained in the step 1) on a quick forging hydraulic press, and finishing the first hot forging after upsetting;

3) removing all soft and hard covering sleeves, returning to the furnace for annealing heat treatment at 1100-1200 ℃;

4) arranging a first hard sheath die at the first end of the high-temperature alloy ingot blank obtained in the step 3), arranging a second hard sheath die at the second end of the high-temperature alloy ingot blank obtained in the step 3) to obtain a blank with a hard sheath, placing the blank with the hard sheath in a heating furnace, heating the blank to 1000-plus-material 1050 ℃ along with the furnace, preserving the heat for 0.5-1.5h, heating the blank to 1100-plus-material 1170 ℃ along with the furnace, preserving the heat for 2-4h, taking the blank out of the furnace, performing soft sheath, and returning the blank to the furnace for heat preservation for 0.5-1.5 h;

5) placing the blank obtained in the step 4) on a quick forging hydraulic press, and finishing the second hot forging after upsetting;

6) removing all soft and hard covering sleeves, returning to the furnace for annealing heat treatment at 1100-1200 ℃;

7) and (4) inspecting, namely performing ultrasonic flaw detection or sampling from the end face to inspect a metallographic microstructure.

In another aspect of the invention, the invention provides the use of a forging method as described above for the preparation of a superalloy forging stock.

In another aspect of the present invention, there is provided a superalloy forging stock using the forging method described above in the process of preparing the superalloy forging stock.

Some embodiments of the present invention will be described in detail below with reference to specific embodiments. The embodiments described below and the features of the embodiments can be combined with each other without conflict.

Examples

Unless otherwise specified, the high temperature alloys in the following examples and comparative examples are GH4096 alloys.

Example 1

The forging method for improving the end surface structure of the high-temperature alloy ingot blank comprises the following steps:

1) smelting and preparing a GH4096 alloy ingot blank by adopting a vacuum induction and electroslag remelting continuous directional solidification process; carrying out homogenization heat treatment on the ingot blank; then rough machining is carried out for peeling till the ingot blank presents metal luster, and the size of the ingot blank is obtained

2) The first hard covering die and the second hard covering die are made of GH4096 alloy ingot blanks, the axial dimension (thickness) is 20mm, and the diameter of an excircle

Preparing a commercially available high-temperature glass fiber blanket with the size specification of 5mm thickness, a first hard cover die, a second hard cover die and a GH4096 alloy ingot blankThe gap between the two and compact the two;

3) according to the requirement that the form and position tolerance is less than 2mm, an argon arc welding mode (an Inconel82 alloy welding wire) is adopted, and the welding is carried out on the joint of the circumferential surfaces and the high-temperature alloy ingot blank; the welded blank is subjected to a subsequent forging process, and a soft packing manner is still required to be adopted for 100% of the surfaces of the ingot blank and the hard packing sleeve;

4) the heating temperature of a first hot forging blank is 1150 ℃, the upsetting deformation rate is 15mm/s, the deformation is 25%, upsetting adopts fetal membrane forging, after upsetting is finished, a hard sheath is separated from an ingot blank in a radial slight rounding mode, upsetting shaping with the deformation of 3% is finally carried out, the blank is returned to a furnace at 1170 ℃ for heat preservation for 2h for annealing, and finally asbestos is wrapped and cooled to the room temperature;

5) for the ingot blank (ingot blank size) obtained by the first fire in the step 4)

Performing second fire forging, wherein the axial size of the hard sleeve is 20mm, and the diameter of the excircle

Heating the blank at 1150 ℃, upsetting the deformation rate of 15mm/s, deforming 25%, upsetting by using a tire membrane forging, separating the hard sheath from the ingot blank by using a radial slight rounding mode after upsetting is finished, upsetting and shaping the deformation of 5%, returning to a furnace at 1160 ℃, keeping the temperature for 2 hours for annealing, and finally cooling the asbestos to room temperature;

6) for the ingot blank (ingot blank size) obtained by the second fire in the step 5)

Performing third fire forging, wherein the axial size of the hard sleeve is 15mm, and the diameter of the excircle

The blank heating temperature is 1140 ℃, the upsetting deformation rate is 15mm/s, the deformation is 35%, upsetting adopts the blank film forging, after upsetting is finished, the hard sheath and the blank are separated by adopting a radial slight rounding mode, finally upsetting and shaping with the deformation of 5% are carried out, the blank is returned to a furnace for annealing at 1150 ℃ for 2 hours, and finally the asbestos is cooled to the room temperature;

7) inspecting the ingot blank obtained in step 6)

The center of the upper end surface of the steel plate is sampled (the sample size is 10 multiplied by 10mm), the obtained microstructure is shown in figure 4, the original coarse columnar crystal structure is eliminated, the mixed crystal structure with the grain size of 200um and 20um coexisting is obtained, and the purpose of cogging is achieved.

Example 2

The forging method for improving the end surface structure of the superalloy ingot blank is the same as that in example 1, except that the thickness of the first hard cover die and the second hard cover die is 15mm in the axial direction of the superalloy ingot blank.

Example 3

The forging method for improving the end surface structure of the superalloy ingot blank is the same as that in example 1, except that the thickness of the first hard cover die and the second hard cover die is 30mm in the axial direction of the superalloy ingot blank.

Example 4

The forging method for improving the end surface structure of the superalloy ingot blank is the same as that in example 1, except that the thickness of the first hard cover die and the second hard cover die is 10mm in the axial direction of the superalloy ingot blank.

Example 5

The forging method for improving the end surface structure of the superalloy ingot blank is the same as that in example 1, except that the thickness of the first hard cover die and the second hard cover die is 40mm in the axial direction of the superalloy ingot blank.

Comparative example 1

The forging method for improving the end surface structure of the high-temperature alloy ingot blank is the same as that in the embodiment 1, except that a first hard cover die and a second hard cover die are not adopted.

The core part of the upper end face of the ingot obtained by forging was sampled (sample size 10X 10mm), and the microstructure obtained is shown in FIG. 5, and it can be seen that the original coarse columnar crystal structure of the superalloy ingot is still retained, and no crystal grain breakage occurs.

Comparative example 2

The forging method for improving the end surface structure of the high-temperature alloy ingot blank is the same as that in the embodiment 1, except that the gaps between the first hard covering die and the GH4096 alloy ingot blank are not filled with the soft covering.

The center portion of the upper end face of the ingot obtained by forging was sampled (sample size 10X 10mm) to obtain a microstructure shown in FIG. 6, and it can be seen that although the columnar crystal structure was broken, a large number of coarse crystals (size larger than 200umm) were present and large crystal grains having a size larger than 500um were present.

Comparative example 3

The forging method for improving the end surface structure of the high-temperature alloy ingot blank is the same as that in the embodiment 1, except that the first hard cover die and the second hard cover die are made of stainless steel.

The ratios of coarse columnar structures (the major axis direction size is more than 500um, and the major-minor axis direction ratio is more than 2) in the ingots obtained by the forging methods of examples 1 to 5 and comparative examples 1 to 3 are shown in table 1 below:

TABLE 1

	Coarse columnar grain structure fraction/%)
		Example 1	0
Example 2	5
		Example 3	2
Example 4	10
		Example 5	0
Comparative example 1	95
		Comparative example 2	60
Comparative example 3	90

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A forging method for improving the end surface structure of a high-temperature alloy ingot blank is characterized by comprising the following steps:

b) upsetting the blank with the hard sheath to obtain an upset ingot blank;

2. The forging method as recited in claim 1, wherein the thickness of each of the first and second hard pack dies is 15 to 30mm independently in the axial direction of the superalloy ingot.

3. The forging method as recited in claim 1, wherein a right angle of a side of the first and second hard pack dies facing the superalloy ingot is rounded.

4. The forging method as recited in claim 3, wherein R5-10 is rounded.

5. The forging method as recited in claim 1, wherein a soft capsule is provided in said void.

6. The forging method as recited in claim 5, wherein the soft jacket includes a glass fiber blanket and glass powder.

7. The forging method as recited in any one of claims 1 to 6, wherein the first hard cover die and the second hard cover die are welded to the superalloy ingot blank by argon arc welding.

8. The forging method as recited in claim 7, wherein a nickel-chromium welding wire material is used as the welding wire in argon arc welding.

9. The forging method as recited in claim 7, wherein the tolerances of cylindricity, parallelism and coaxiality of the welded blank with the hard clad sheath are each independently within ± 2 mm.

10. The forging method as recited in claim 1, wherein in the step b), the blank with the hard sheath is first subjected to heat preservation at 1050 ℃ of 1000 ℃ and 1050 ℃ for 0.5-1.5h, and then subjected to heat preservation at 1170 ℃ of 1100 and 2-4h, and then subjected to upsetting treatment.

11. The forging method as recited in claim 10, wherein the blank with the hard sheath is first subjected to heat preservation at 1050 ℃ for 0.5-1.5h and then at 1170 ℃ for 2-4h, then the blank with the hard sheath is covered with the soft sheath, and finally the blank covered with the soft sheath is subjected to upsetting treatment.

12. The forging method as recited in claim 11, wherein after the surface of the blank with the hard capsule is coated with the soft capsule, the blank is subjected to heat preservation at 1100 ℃ and 1170 ℃ for 0.5-1.5h, and then the blank coated with the soft capsule is subjected to upsetting treatment.

13. The forging method as recited in claim 10, wherein in the step b), a deformation rate of the upsetting process is 10 to 20mm/s, and/or a deformation amount of the upsetting process is 20 to 50%.

14. The forging method as recited in any one of claims 1 to 6 and 10 to 13, wherein in step c), the amount of deformation of the upset shape is not less than 0% and not more than 10%.

15. The forging method as recited in claim 14, wherein the temperature of the annealing treatment is 1100-1200 ℃.

16. The forging method as recited in claim 14, wherein steps a) to c) are repeated 2 to 4 times.

17. A forging method as recited in any one of claims 1 to 6 and 10 to 13, wherein said superalloy ingot is subjected to a homogenization heat treatment prior to step a).

18. The forging method as recited in claim 17, wherein the homogenization heat treatment comprises: the high-temperature alloy ingot blank is firstly subjected to heat preservation at the temperature of 400-850 ℃ for not less than 2h, then is subjected to heat preservation at the temperature of 1050-1100 ℃ for not less than 4h, then is subjected to heat preservation at the temperature of 1140-1180 ℃ for not less than 4h, and finally is subjected to heat preservation at the temperature of 1180-1210 ℃ for not less than 24 h.

19. The forging method as recited in any one of claims 1 to 6 and 10 to 13, wherein the superalloy comprises one of a nickel-based superalloy, an iron-nickel-based superalloy, and a cobalt-based superalloy.

20. The forging method as recited in claim 19, wherein the superalloy has an aspect ratio of 3 to 5.

21. The forging method as recited in claim 19, wherein the superalloy comprises a composition having the following mass fractions: co: 13.0-21.0%, Cr: 12 to 16 percent; mo: 3.5-4.5%, W: 2.0-4.0%, Al: 1.9-3.5%, Ti: 3.5 to 4.5 percent; nb: 0.5-1.5%; ta: 0.0 to 3.0 percent; b: 0.010-0.040%; c: 0.005-0.060%; zr: 0.030-0.060%; fe: 0 to 0.5 percent; and the balance Ni.

22. The forging method of claim 19, wherein the high temperature alloy comprises a GH4096 alloy.

23. Use of a forging process according to any one of claims 1 to 22 in the preparation of a superalloy forging stock.

24. A superalloy forging stock, wherein the forging method of any of claims 1-22 is used in the process of making the superalloy forging stock.