A GH4720Li alloy forge piece and a preparation method thereof, and a gas turbine

Abstract

The present application relates to alloy processing technical field, and more particularly to a kind of GH4720Li alloy forgings and its preparation method, gas turbine.The preparation method includes: GH4720Li alloy ingot is sequentially carried out first upsetting, first lengthening, second upsetting and second lengthening, then heat continuous rolling is carried out after 1160~1190 ℃ 4~10 h heat preservation, then free forging is carried out, then organization control pretreatment is carried out, and free forging blank is obtained;Free forging blank is carried out die forging and then carried out solution treatment and aging treatment in sequence;In GH4720Li alloy, carbon content is less than 0.01%, and chromium content is 17.5%~19%.The method can improve the high temperature endurance of forging, and the grain size of the forging prepared by the method is 2~4, room temperature tensile strength is ≥1400MPa, 650 ℃ tensile strength is ≥1280MPa, 850 ℃ / 300MPa endurance life is ≥100h.

Description

TECHNICAL FIELD

[0001] The present application relates to the alloy processing technical field, and in particular to a GH4720Li alloy forge piece and a preparation method thereof, and a gas turbine. BACKGROUND

[0002] GH4720Li alloy is commonly used to prepare turbine disc forge pieces for aero-engine under the condition of 700-750℃ long-term use. In the prior art, the C content of GH4720Li alloy is 0.01%-0.02%, the Cr content is 15.5%-16.5%, the grain size of the forge piece reaches 8 levels or finer, and the forge piece has higher high-temperature tensile property and fatigue property. However, for the forge piece for a gas turbine, the existing preparation method cannot meet the requirement of GH4720Li alloy on high-temperature endurance property.

[0003] The existing preparation method of GH4720Li alloy mainly includes the following steps: upsetting + radial forging, or one-way elongation for bar breaking down; die forging to complete the shaping of the forge piece; and heat treatment.

[0004] However, the method has the following shortcomings: (1) M 23 C6 and M6C carbides are formed on the grain boundary, a Cr-poor area is formed at the grain boundary, the oxidation resistance at the grain boundary is reduced, and the grain boundary strength is reduced. (2) The Cr content is low, and the oxidation resistance of the forge piece at 850℃ needs to be improved. (3) The grain size of the forge piece reaches 8 levels or finer, and the endurance life at 850℃ / 300MPa is low, which cannot meet the use requirement of the gas turbine.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] A first object of the present application is to provide a preparation method of a GH4720Li alloy forge piece, which can significantly improve the high-temperature endurance property of GH4720Li alloy, and the grain size of the GH4720Li alloy forge piece prepared by the method is 2-4 levels, the room-temperature tensile strength is ≥1400MPa, the 650℃ tensile strength is ≥1280MPa, and the endurance life at 850℃ / 300MPa is ≥100h.

[0007] A second object of the present application is to provide a GH4720Li alloy forge piece.

[0008] A third object of the present application is to provide a gas turbine.

[0009] In order to achieve the above objects of the present application, the following technical scheme is adopted:

[0010] The present application provides a preparation method of a GH4720Li alloy forge piece, which includes the following steps:

[0011] (a) a GH4720Li alloy ingot is subjected to first upsetting, first elongation, second upsetting and second elongation in sequence to obtain a rod blank;

[0012] (b) the rod blank is subjected to hot continuous rolling after being kept at 1160-1190℃ for 4-10h to obtain a rolled rod blank;

[0013] (c) the rolled rod blank is subjected to free forging and then subjected to structure regulating pretreatment to obtain a free forging blank;

[0014] The structure regulating pretreatment comprises keeping at 1160-1180℃ for 4-6h and then keeping at 1120-1140℃ for 16-24h.

[0015] (d) the free forging blank is subjected to die forging and then subjected to solid solution treatment and aging treatment in sequence to obtain a GH4720Li alloy forge piece.

[0016] In the GH4720Li alloy, the carbon content is less than 0.01% and the chromium content is 17.5%-19% by mass percentage.

[0017] In the specific embodiment of the present application, in step (a), the GH4720Li alloy ingot is subjected to first upsetting after being kept at 1200-1220℃ for 40-60h to obtain a first blank; preferably, the deformation amount of the first upsetting is 10%-40%.

[0018] Preferably, the first blank is kept at 1220℃ for 4-8h, then cooled down to 1180-1200℃ in the furnace, kept at 1180-1200℃ for 30-50h, and then subjected to first elongation to obtain a second blank; more preferably, the deformation amount of the first elongation is 20%-40%.

[0019] Preferably, the second blank is kept at 1200℃ for 4-8h, then cooled down to 1160-1180℃ in the furnace, kept at 1160-1180℃ for 30-50h, and then subjected to second upsetting to obtain a third blank; more preferably, the deformation amount of the second upsetting is 10%-40%.

[0020] Preferably, the third blank is kept at 1180℃ for 4-8h, then cooled down to 1140-1160℃ in the furnace, kept at 1140-1160℃ for 30-50h, and then subjected to second elongation to obtain a rod blank; more preferably, the deformation amount of the second elongation is 20%-40%.

[0021] In the specific embodiment of the present application, in step (b), the deformation amount of the hot continuous rolling is 10%-40%.

[0022] In the specific embodiment of the present application, in step (c), the rolling bar is kept at 1140-1180 °C for 4-10 h before the free forging is performed;

[0023] Preferably, the deformation of the free forging is 40%-60%; and / or, the pressing speed of the free forging is 5-15 mm / s;

[0024] Preferably, the rolling bar is subjected to hard jacketing treatment using asbestos and steel jacket before heating; more preferably, the thickness of the asbestos is 8-15 mm, the thickness of the steel jacket is 2-3 mm, and the diameter of the rolling bar is 180-320 mm.

[0025] In the specific embodiment of the present application, in step (c), the tissue regulation pretreatment specifically comprises: keeping at 1160-1180 °C for 4-6 h, then cooling to 1120-1140 °C at a speed of 5-8 °C / min, keeping for 16-24 h, and then cooling to room temperature at a speed of 2-5 °C / min.

[0026] In the specific embodiment of the present application, in step (d), the free forging blank is kept at 1140-1180 °C for 4-10 h before the die forging is performed;

[0027] Preferably, the deformation of the die forging is 20%-40%; and / or, the pressing speed of the die forging is 5-15 mm / s;

[0028] Preferably, the free forging blank is subjected to hard jacketing treatment using asbestos and steel jacket before heating; more preferably, the thickness of the asbestos is 8-15 mm, the thickness of the steel jacket is 2-3 mm, and the diameter of the free forging blank is 200-400 mm.

[0029] Preferably, the mold is preheated before the die forging; more preferably, the preheating temperature of the mold is not less than 500 °C.

[0030] In the specific embodiment of the present application, in step (d), the solid solution treatment comprises: keeping at 1150-1170 °C for 4-6 h, then air cooling to room temperature, and then keeping at 1180-1200 °C for 2-8 h, and then air cooling to room temperature.

[0031] In the specific embodiment of the present application, in step (d), the aging treatment comprises: keeping at 800-950 °C for 8-24 h, then air cooling to room temperature, and then keeping at 720-820 °C for 8-24 h, and then air cooling to room temperature.

[0032] The present application also provides a GH4720Li alloy forging piece, which is mainly prepared by the preparation method of the GH4720Li alloy forging piece as described above;

[0033] Preferably, the grain size of the GH4720Li alloy forge piece is 2-4 grade.

[0034] Preferably, the room temperature tensile strength of the GH4720Li alloy forge piece is ≥1400MPa, and the 650℃ tensile strength is ≥1280MPa.

[0035] Preferably, the 850℃ / 300MPa endurance life of the GH4720Li alloy forge piece is ≥100h.

[0036] The application also provides a gas turbine mainly made of the GH4720Li alloy forge piece as described above.

[0037] Compared with the prior art, the application has the following beneficial effects:

[0038] (1) The application can make the grain size of the GH4720Li alloy forge piece be 2-4 grade by controlling the carbon content of the GH4720Li alloy to be less than 0.01%, the chromium content to be 17.5%-19%, and performing hot continuous rolling and microstructure regulation pretreatment, etc., which can improve the 850℃ oxidation resistance and tensile strength of the forge piece, and significantly improve the high temperature endurance performance of the GH4720Li alloy forge piece.

[0039] (2) The room temperature tensile strength of the GH4720Li alloy forge piece made by the application is ≥1400MPa, the 650℃ tensile strength is ≥1280MPa, and the 850℃ / 300MPa endurance life is ≥100h. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0041] Figure 1 The metallographic structure diagram of the GH4720Li alloy forge piece provided for the example 3 of the application;

[0042] Figure 2 The metallographic structure diagram of the GH4720Li alloy forge piece provided for the comparative example 6 of the application. DETAILED DESCRIPTION

[0043] The technical solutions of the present application will be described clearly and completely below in combination with the drawings and specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. The specific conditions are not specified in the embodiments, and are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are conventional products that can be purchased on the market.

[0044] In a first aspect, the present application provides a preparation method of a GH4720Li alloy forge piece for a gas turbine, comprising the following steps:

[0045] (a) sequentially performing first upsetting, first elongation, second upsetting and second elongation on a GH4720Li alloy ingot to obtain a rod blank.

[0046] (b) after the rod blank obtained in step (a) is kept at 1160-1190°C (including but not limited to any one of 1165°C, 1170°C, 1175°C, 1180°C, 1185°C or a range value between any two of them) for 4-10h (including but not limited to any one of 5h, 6h, 7h, 8h, 9h or a range value between any two of them), performing hot continuous rolling to obtain a rolled rod blank.

[0047] (c) performing free forging on the rolled rod blank, and then performing microstructure regulation pretreatment to obtain a free forging blank.

[0048] Wherein, the microstructure regulation pretreatment comprises: keeping at 1160-1180°C (including but not limited to any one of 1165°C, 1170°C, 1175°C, 1178°C or a range value between any two of them) for 4-6h (including but not limited to any one of 4.5h, 5h, 5.5h or a range value between any two of them), and then keeping at 1120-1140°C (including but not limited to any one of 1123°C, 1125°C, 1128°C, 1130°C, 1133°C, 1135°C, 1138°C or a range value between any two of them) for 16-24h (including but not limited to any one of 17h, 18h, 19h, 20h, 21h, 22h, 23h or a range value between any two of them).

[0049] (d) performing die forging on the free forging blank, and then sequentially performing solid solution treatment and aging treatment to obtain a GH4720Li alloy forge piece.

[0050] The GH4720Li alloy contains less than 0.01% of carbon and 17.5-19% of chromium.

[0051] In some specific embodiments of the present application, the content of carbon includes but is not limited to any one of 0.009%, 0.008%, 0.007%, 0.006%, 0.005%, 0.004%, 0.003%, 0.002%, 0.001%, 0.0001% or a range value between any two of them; the content of chromium includes but is not limited to any one of 17.6%, 17.7%, 17.8%, 17.9%, 18.0%, 18.1%, 18.2%, 18.3%, 18.4%, 18.5%, 18.6%, 18.7%, 18.9% or a range value between any two of them.

[0052] The present application can produce GH4720Li alloy forgings with grain size of 2-4 levels by controlling the content of carbon in GH4720Li alloy to be less than 0.01%, the content of chromium to be 17.5-19% and adopting hot continuous rolling and microstructure regulation pretreatment, which can improve the oxidation resistance at 850°C and tensile strength of the forgings and significantly improve the high temperature stress rupture properties of GH4720Li alloy forgings.

[0053] The GH4720Li alloy forgings produced by the preparation method can be used to produce gas turbines, which solves the problems of not meeting the requirements of GH4720Li alloy on high temperature stress rupture properties, low grain boundary strength and poor oxidation resistance at 850°C in the prior art.

[0054] Specifically, by controlling the content of carbon in GH4720Li alloy to be less than 0.01%, the number of M 23 C6 and M6C carbides at the grain boundary is reduced, the formation of Cr-poor zone is inhibited, the oxidation resistance of the grain boundary is improved, and thus the grain boundary strength is improved; by controlling the content of chromium in the alloy to be 17.5-19%, the high temperature oxidation resistance of the forgings is improved; by heat treating the rod blank at 1160-1190°C for 4-10h and then performing hot continuous rolling, the hot rolling time is shortened, the temperature drop is reduced, the formation of coarse grain structure at the edge of the rod blank is inhibited, and thus the uniformity of the structure of the rolled rod blank is improved; by heat treating the forged blank after free forging at 1160-1180°C for 4-6h and then at 1120-1140°C for 16-24h for microstructure regulation pretreatment, the microstructure of the forged blank is completely dynamically recrystallized, the plasticity of the forged blank is improved, and thus the hot working property of the forged blank is improved and the tendency of cracking in subsequent die forging is reduced.

[0055] In some embodiments of the present application, the GH4720Li alloy has the following composition by mass percentage: carbon <0.01%, chromium 17.5%-19%, zirconium 0.025%-0.05%, molybdenum 2.75-3.25%, tungsten 1.0%-1.5%, cobalt 14%-15.5%, iron ≤0.5%, aluminum 2.25%-2.75%, titanium 4.75%-5.25%, phosphorus ≤0.015%, boron 0.01%-0.02%, copper ≤0.1%, silicon ≤0.2%, manganese ≤0.15%, sulfur ≤0.002%, and the balance being nickel.

[0056] In some embodiments of the present application, in step (a), the GH4720Li alloy ingot is heated to 300°C and then heated to 1200-1220°C (including but not limited to any one of 1203°C, 1205°C, 1208°C, 1210°C, 1212°C, 1215°C, 1218°C, or a range between any two of them) at a rate of 10°C / min, and then first upset drawing is performed after holding for 40-60 h (including but not limited to any one of 42 h, 45 h, 47 h, 50 h, 53 h, 55 h, 58 h, or a range between any two of them), to obtain a first billet.

[0057] Preferably, the first upset drawing has a deformation of 10%-40%; including but not limited to any one of 15%, 20%, 25%, 30%, 35%, or a range between any two of them.

[0058] Preferably, the first billet is reheated at 1220°C for 4-8 h (including but not limited to any one of 5 h, 6 h, 7 h, or a range between any two of them), then cooled in the furnace to 1180-1200°C (including but not limited to any one of 1183°C, 1185°C, 1188°C, 1190°C, 1193°C, 1195°C, 1198°C, or a range between any two of them), and then held for 30-50 h (including but not limited to any one of 32 h, 35 h, 37 h, 40 h, 43 h, 45 h, 48 h, or a range between any two of them), and then first elongation drawing is performed to obtain a second billet.

[0059] More preferably, the first elongation drawing has a deformation of 20%-40%; including but not limited to any one of 23%, 25%, 28%, 30%, 32%, 35%, 38%, or a range between any two of them.

[0060] Preferably, the second billet is reheated at 1200℃ for 4-8h (including but not limited to any one of 5h, 6h, 7h or a range value between any two of them), then furnace-cooled to 1160-1180℃ (including but not limited to any one of 1163℃, 1165℃, 1168℃, 1170℃, 1173℃, 1175℃, 1178℃ or a range value between any two of them), and held for 30-50h (including but not limited to any one of 32h, 35h, 37h, 40h, 43h, 45h, 48h or a range value between any two of them) before the second upsetting to obtain a third billet.

[0061] More preferably, the deformation amount of the second upsetting is 10%-40%; including but not limited to any one of 15%, 20%, 25%, 30%, 35% or a range value between any two of them.

[0062] Preferably, the third billet is reheated at 1180℃ for 4-8h (including but not limited to any one of 5h, 6h, 7h or a range value between any two of them), then furnace-cooled to 1140-1160℃ (including but not limited to any one of 1143℃, 1145℃, 1148℃, 1150℃, 1153℃, 1155℃, 1158℃ or a range value between any two of them), and held for 30-50h (including but not limited to any one of 32h, 35h, 37h, 40h, 43h, 45h, 48h or a range value between any two of them) before the second drawing to obtain a rod blank.

[0063] More preferably, the deformation amount of the second drawing is 20%-40%, including but not limited to any one of 23%, 25%, 28%, 30%, 32%, 35%, 38% or a range value between any two of them.

[0064] In some preferred embodiments of the present application, the final forging temperature of the second drawing is not lower than 1100℃.

[0065] The multi-stage high-temperature homogenization is cooperated with upsetting and drawing deformation to complete the breaking down of the rod, which is beneficial to improve the breaking efficiency of the dendrite of the ingot, and meanwhile, the equiaxed grain boundaries formed provide more channels for the diffusion of the segregation elements, thereby improving the segregation elimination effect.

[0066] In the specific embodiments of the present application, in step (b), the deformation amount of the hot continuous rolling is 10%-40%, including but not limited to any one of 15%, 20%, 25%, 30%, 35% or a range value between any two of them.

[0067] In some preferred embodiments of the present application, the hot continuous rolling is performed by using a hot continuous rolling mill train.

[0068] In some preferred embodiments of the present application, the finish rolling temperature of the hot continuous rolling is not lower than 1100℃.

[0069] In some specific embodiments of the present application, after the rolling billet is kept at 1140-1180℃ (including but not limited to any one of the point values of 1145℃, 1150℃, 1155℃, 1160℃, 1165℃, 1170℃, 1175℃ or the range value between any two of them) for 4-10h (including but not limited to any one of the point values of 5h, 6h, 7h, 8h, 9h or the range value between any two of them), the free forging is performed.

[0070] Preferably, the deformation amount of the free forging is 40%-60%; including but not limited to any one of the point values of 43%, 45%, 48%, 50%, 52%, 55%, 58% or the range value between any two of them. And / or, the downward pressing speed of the free forging is 5-15mm / s; including but not limited to any one of the point values of 6mm / s, 7mm / s, 8mm / s, 9mm / s, 10mm / s, 11mm / s, 12mm / s, 13mm / s, 14mm / s or the range value between any two of them.

[0071] In some preferred embodiments of the present application, the free forging is performed by using a 30000-80000t forging press.

[0072] In some preferred embodiments of the present application, the finish forging temperature of the free forging is not lower than 1100℃.

[0073] Preferably, before the rolling billet is heated, a hard jacketing treatment is performed by using asbestos and a steel jacket; more preferably, the thickness of the asbestos is 8-15mm, the thickness of the steel jacket is 2-3mm, and the diameter of the rolling billet is 180-320mm.

[0074] In some specific embodiments of the present application, the thickness of the asbestos includes but is not limited to any one of the point values of 9mm, 10mm, 11mm, 12mm, 13mm, 14mm or the range value between any two of them; the thickness of the steel jacket includes but is not limited to any one of the point values of 2.1mm, 2.3mm, 2.5mm, 2.7mm, 2.9mm or the range value between any two of them; and the diameter of the rolling billet includes but is not limited to any one of the point values of 190mm, 200mm, 220mm, 240mm, 250mm, 270mm, 290mm, 300mm or the range value between any two of them.

[0075] In the specific embodiment of the present application, in step (c), the tissue regulation pretreatment specifically comprises: after holding at 1160-1180°C (including but not limited to any one of 1162°C, 1165°C, 1168°C, 1170°C, 1173°C, 1175°C, 1178°C or a range value between any two of them) for 4-6h (including but not limited to any one of 4.5h, 5h, 5.5h or a range value between any two of them), cooling to 1120-1140°C (including but not limited to any one of 1122°C, 1125°C, 1128°C, 1130°C, 1133°C, 1135°C, 1138°C or a range value between any two of them) at a rate of 5-8°C / min (including but not limited to any one of 5.5°C / min, 6°C / min, 6.5°C / min, 7°C / min, 7.5°C / min or a range value between any two of them), holding for 16-24h (including but not limited to any one of 17h, 18h, 19h, 20h, 21h, 22h, 23h or a range value between any two of them), and then air cooling to room temperature at a rate of 2-5°C / min (including but not limited to any one of 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min or a range value between any two of them).

[0076] In the specific embodiment of the present application, in step (d), the free forging blank is held at 1140-1180°C (including but not limited to any one of 1142°C, 1145°C, 1150°C, 1155°C, 1160°C, 1165°C, 1170°C, 1175°C, 1178°C or a range value between any two of them) for 4-10h (including but not limited to any one of 5h, 6h, 7h, 8h, 9h or a range value between any two of them) before being subjected to die forging.

[0077] Preferably, the deformation of the die forging is 20%-40%; including but not limited to any one of 23%, 25%, 28%, 30%, 32%, 35%, 38% or a range value between any two of them.

[0078] And / or, the pressing speed of the die forging is 5-15mm / s; including but not limited to any one of 6mm / s, 7mm / s, 8mm / s, 9mm / s, 10mm / s, 11mm / s, 12mm / s, 13mm / s, 14mm / s or a range value between any two of them.

[0079] In some preferred embodiments of the present application, the die forging is performed using a 30000-80000t forging press.

[0080] In some preferred embodiments of the present application, the final forging temperature of the die forging is not less than 1100℃.

[0081] Preferably, the free forging blank is subjected to hard jacketing treatment using asbestos and a steel jacket before heating; more preferably, the thickness of the asbestos is 8-15mm, the thickness of the steel jacket is 2-3mm, and the diameter of the free forging blank is 200-400mm.

[0082] In some specific embodiments of the present application, the thickness of the asbestos includes but is not limited to any one of 9mm, 10mm, 11mm, 12mm, 13mm, 14mm or a range value between any two of them; the thickness of the steel jacket includes but is not limited to any one of 2.1mm, 2.3mm, 2.5mm, 2.7mm, 2.9mm or a range value between any two of them; and the diameter of the free forging blank includes but is not limited to any one of 220mm, 250mm, 270mm, 300mm, 330mm, 350mm, 380mm or a range value between any two of them.

[0083] Preferably, the die is preheated before the die forging; more preferably, the preheating temperature of the die is not less than 500℃, including but not limited to any one of 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃ or a range value between any two of them.

[0084] The present application can ensure that the forged piece obtains appropriate grain size through dynamic recrystallization and ensures uniform grain structure of the forged piece by adopting specific die forging parameters.

[0085] In the specific embodiments of the present application, in step (d), the solution treatment includes: air cooling to room temperature after holding at 1150-1170℃ (including but not limited to any one of 1152℃, 1155℃, 1158℃, 1160℃, 1163℃, 1165℃, 1168℃ or a range value between any two of them) for 4-6h (including but not limited to any one of 4.5h, 5h, 5.5h or a range value between any two of them), and then air cooling to room temperature after holding at 1180-1200℃ (including but not limited to any one of 1182℃, 1185℃, 1188℃, 1190℃, 1193℃, 1195℃, 1198℃ or a range value between any two of them) for 2-8h (including but not limited to any one of 3h, 4h, 5h, 6h, 7h or a range value between any two of them).

[0086] In some specific embodiments of the present application, the solution treatment specifically comprises: charging at 500-600℃, heating at a rate of 10℃ / min to 1150-1170℃, holding for 4-6h, and then air cooling to room temperature; and then charging at 500-700℃, heating at a rate of 10℃ / min to 1180-1200℃, holding for 2-8h, and then air cooling to room temperature.

[0087] By using the specific solution treatment parameters, the grain size of the forged piece can be controlled, and the saturation of the base alloying elements can be improved, and the subsequent aging treatment effect can be improved.

[0088] In the specific embodiments of the present application, in step (d), the aging treatment comprises: holding at 800-950℃ (including but not limited to any one of 820℃, 850℃, 880℃, 900℃, 920℃, 940℃, or a range value between any two of them) for 8-24h (including but not limited to any one of 9h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, or a range value between any two of them), and then air cooling to room temperature; and then holding at 720-820℃ (including but not limited to any one of 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, 810℃, or a range value between any two of them) for 8-24h (including but not limited to any one of 9h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, or a range value between any two of them), and then air cooling to room temperature.

[0089] In some specific embodiments of the present application, the aging treatment specifically comprises: charging at 300-400℃, heating at a rate of 10℃ / min to 800-950℃, holding for 8-24h, and then air cooling to room temperature; and then charging at 300-400℃, heating at a rate of 10℃ / min to 720-820℃, holding for 8-24h, and then air cooling to room temperature.

[0090] By using the specific aging treatment parameters, the amount, morphology and size of the γ' phase can be effectively controlled, and thus the strength of the forged piece can be ensured.

[0091] In some specific embodiments of the present application, the GH4720Li alloy ingot is prepared by triple smelting. The triple smelting comprises vacuum induction, electroslag remelting and vacuum consumable melting. The parameters of the triple smelting can use any conventional smelting parameters of the GH4720Li alloy.

[0092] In some specific embodiments of the present application, the size of the GH4720Li alloy ingot is Φ508mm.

[0093] In a second aspect, the present application provides a GH4720Li alloy forge piece, which is prepared by the method for preparing the GH4720Li alloy forge piece as described above.

[0094] Preferably, the grain size of the GH4720Li alloy forge piece is grade 2 to grade 4, including but not limited to any one of the point values of grade 2, grade 3 and grade 4 or a range value between any two of them.

[0095] Preferably, the tensile strength at room temperature of the GH4720Li alloy forge piece is ≥1400MPa, including but not limited to any one of the point values of 1410MPa, 1420MPa, 1430MPa, 1440MPa, 1445MPa, 1450MPa, 1460MPa, 1470MPa, 1480MPa, 1490MPa and 1500MPa or a range value between any two of them.

[0096] The tensile strength at 650℃ of the GH4720Li alloy forge piece is ≥1280MPa, including but not limited to any one of the point values of 1285MPa, 1290MPa, 1295MPa, 1300MPa, 1310MPa, 1320MPa, 1330MPa and 1350MPa or a range value between any two of them.

[0097] Preferably, the 850℃ / 300MPa endurance life of the GH4720Li alloy forge piece is ≥100h, including but not limited to any one of the point values of 110h, 120h, 130h, 140h and 150h or a range value between any two of them.

[0098] In a third aspect, the present application provides a gas turbine, which is prepared by the GH4720Li alloy forge piece as described above.

[0099] The GH4720Li alloy forge piece prepared by the present application has good high-temperature endurance performance and can be used to prepare a gas turbine.

[0100] The embodiments of the present application will be described in detail below with reference to the examples, but those skilled in the art will understand that the following examples are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. The specific conditions not noted in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not noted by the manufacturer, which are all conventional products that can be obtained by market purchase.

[0101] Example 1

[0102] The preparation method of the GH4720Li alloy forge piece provided in the present example includes the following steps:

[0103] (1) GH4720Li alloy ingot with a size of Φ508mm is obtained by a triple process (vacuum induction, electroslag remelting and vacuum consumable melting).

[0104] The GH4720Li alloy comprises, by mass percentage, carbon 0.0095%, chromium 19%, zirconium 0.05%, molybdenum 3.25%, tungsten 1.5%, cobalt 15.5%, iron 0.5%, aluminum 2.75%, titanium 5.25%, phosphorus 0.015%, boron 0.02%, copper 0.1%, silicon 0.2%, manganese 0.15%, sulfur 0.002%, and the balance of nickel.

[0105] (2) Multi-stage high-temperature homogenization and upsetting and elongation deformation are cooperatively controlled to complete the breakdown of the rod:

[0106] The GH4720Li alloy ingot obtained in step (1) is heated to 1220℃ at a speed of 10℃ / min and kept for 60h, and then first upsetting is performed to obtain a first billet; wherein the deformation of the first upsetting is 40%.

[0107] The first billet is reheated at 1220℃ for 8h, and then the furnace is cooled to 1200℃, and kept for 50h, and then first elongation is performed to obtain a second billet; wherein the deformation of the first elongation is 40%.

[0108] The second billet is reheated at 1200℃ for 8h, and then the furnace is cooled to 1180℃, and kept for 50h, and then second upsetting is performed to obtain a third billet; wherein the deformation of the second upsetting is 40%.

[0109] The third billet is reheated at 1180℃ for 8h, and then the furnace is cooled to 1160℃, and kept for 50h, and then second elongation is performed to obtain a rod billet; wherein the deformation of the second elongation is 40%, and the final forging temperature is not lower than 1100℃.

[0110] (3) The rod billet obtained in step (2) is kept at 1190℃ for 10h, and then hot continuous rolling is performed to obtain a rolled rod billet; wherein the deformation of the hot continuous rolling is 40%, and the final rolling temperature is not lower than 1100℃.

[0111] (4) The rolled rod billet obtained in step (3) is kept at 1180℃ for 10h, and then free forging is performed by using an 80000t forging press; the deformation of the free forging is 60%, the pressing speed is 15mm / s, the final forging temperature is not lower than 1100℃, the rolled rod billet is hard packed before reheating by using asbestos and steel sleeve, the thickness of the asbestos is 15mm, the thickness of the steel sleeve is 3mm, and the diameter of the rolled rod billet is 320mm.

[0112] (5) The free forging billet obtained in step (4) is subjected to a structure regulation pretreatment to obtain a free forging billet. The structure regulation pretreatment specifically comprises: holding at 1180℃ for 6h, then cooling to 1140℃ at a speed of 8℃ / min, holding for 24h, and then cooling to room temperature at a speed of 5℃ / min.

[0113] (6) The free forging billet obtained in step (5) is subjected to die forging at 1180℃ (die forging temperature) for 10h using an 80000t forging press, wherein the deformation amount of the die forging is 40%, the pressing speed is 15mm / s, the final forging temperature is not lower than 1100℃, the free forging billet is subjected to hard cladding treatment using asbestos and a steel sleeve before heating, the die is preheated to a temperature not lower than 500℃ before die forging, the thickness of the asbestos is 15mm, the thickness of the steel sleeve is 3mm, and the diameter of the free forging billet is 320mm.

[0114] (7) The die forging billet obtained in step (6) is subjected to solid solution treatment. The solid solution treatment specifically comprises: loading into a furnace at 600℃, then heating to 1170℃ (first solid solution temperature) at a speed of 10℃ / min, holding for 6h, and then air cooling to room temperature; and then loading into a furnace at 700℃, heating to 1200℃ (second solid solution temperature) at a speed of 10℃ / min, holding for 8h, and then air cooling to room temperature.

[0115] (8) The die forging billet obtained in step (7) is subjected to aging treatment to obtain a GH4720Li alloy forging. The aging treatment specifically comprises: loading into a furnace at 400℃, heating to 950℃ (first aging temperature) at a speed of 10℃ / min, holding for 24h, and then air cooling to room temperature; and then loading into a furnace at 400℃, heating to 820℃ (second aging temperature) at a speed of 10℃ / min, holding for 24h, and then air cooling to room temperature.

[0116] Example 2

[0117] (1) A GH4720Li alloy ingot with a size of Φ508mm is obtained by a triple process (vacuum induction, electroslag remelting and vacuum consumable melting).

[0118] The composition of the GH4720Li alloy includes, by mass percentage: carbon 0.005%, chromium 17.5%, zirconium 0.025%, molybdenum 2.75%, tungsten 1.0%, cobalt 14%, iron 0.1%, aluminum 2.25%, titanium 4.75%, phosphorus 0.005%, boron 0.01%, copper 0.01%, silicon 0.05%, manganese 0.05%, sulfur 0.0005%, and the balance being nickel.

[0119] (2) Multi-stage high-temperature homogenization and upsetting and elongation deformation are cooperatively controlled to complete the breakdown of the rod:

[0120] The GH4720Li alloy ingot obtained in step (1) is put into a furnace at 300℃, heated to 1200℃ at a speed of 10℃ / min, and after holding for 40h, first upsetting is performed to obtain a first billet; wherein the deformation of the first upsetting is 10%.

[0121] The first billet is re-melted at 1220℃ for 4h, and then furnace-cooled to 1180℃, and after holding for 30h, first drawing is performed to obtain a second billet; wherein the deformation of the first drawing is 20%.

[0122] The second billet is re-melted at 1200℃ for 4h, and then furnace-cooled to 1160℃, and after holding for 30h, second upsetting is performed to obtain a third billet; wherein the deformation of the second upsetting is 10%.

[0123] The third billet is re-melted at 1180℃ for 4h, and then furnace-cooled to 1140℃, and after holding for 30h, second drawing is performed to obtain a rod billet; wherein the deformation of the second drawing is 20%, and the final forging temperature is not lower than 1100℃.

[0124] (3) The rod billet obtained in step (2) is held at 1160℃ for 4h, and then hot continuous rolling is performed by using a hot continuous rolling mill to obtain a rolled rod billet; wherein the deformation of the hot continuous rolling is 10%, and the final rolling temperature is not lower than 1100℃.

[0125] (4) The rolled rod billet obtained in step (3) is held at 1140℃ for 4h, and then free forging is performed by using a 30000t forging press, the deformation of the free forging is 40%, the pressing speed is 5mm / s, the final forging temperature is not lower than 1100℃, the rolled rod billet is hard packed by using asbestos and steel sleeve before reheating, the thickness of the asbestos is 8mm, the thickness of the steel sleeve is 2mm, and the diameter of the rolled rod billet is 180mm.

[0126] (5) The forged billet obtained in step (4) is subjected to structure regulation pretreatment to obtain a free forging billet; wherein the structure regulation pretreatment specifically comprises: holding at 1160℃ for 4h, then cooling to 1120℃ at a speed of 5℃ / min, holding for 16h, and then cooling to room temperature at a speed of 2℃ / min.

[0127] (6) The free forging billet obtained in step (5) is held at 1140℃ for 4h, and then die forging is performed by using a 30000t forging press, wherein the deformation of the die forging is 20%, the pressing speed is 5mm / s, the final forging temperature is not lower than 1100℃, the free forging billet is hard packed by using asbestos and steel sleeve before reheating, the die is preheated to a temperature not lower than 500℃ before die forging, the thickness of the asbestos is 8mm, the thickness of the steel sleeve is 2mm, and the diameter of the free forging billet is 180mm.

[0128] (7) The forged blank obtained in step (6) is subjected to solid solution treatment. Specifically, the solid solution treatment comprises: loading into the furnace at 500 DEG C, heating to 1150 DEG C at a rate of 10 DEG C / min, holding for 4 h, and then air cooling to room temperature; and then loading into the furnace at 500 DEG C, heating to 1180 DEG C at a rate of 10 DEG C / min, holding for 2 h, and then air cooling to room temperature.

[0129] (8) The forged blank obtained in step (7) is subjected to aging treatment to obtain the GH4720Li alloy forge piece. Specifically, the aging treatment comprises: loading into the furnace at 300 DEG C, heating to 800 DEG C at a rate of 10 DEG C / min, holding for 8 h, and then air cooling to room temperature; and then loading into the furnace at 300 DEG C, heating to 720 DEG C at a rate of 10 DEG C / min, holding for 8 h, and then air cooling to room temperature.

[0130] Example 3

[0131] (1) A GH4720Li alloy ingot with a size of Φ508 mm is obtained by a triple process (vacuum induction, electroslag remelting and vacuum consumable melting).

[0132] Specifically, the GH4720Li alloy comprises, by mass percent: carbon 0.007%, chromium 18%, zirconium 0.04%, molybdenum 3%, tungsten 1.25%, cobalt 15%, iron 0.3%, aluminum 2.5%, titanium 5%, phosphorus 0.01%, boron 0.015%, copper 0.05%, silicon 0.1%, manganese 0.1%, sulfur 0.001%, and the balance of nickel.

[0133] (2) Multi-stage high-temperature homogenization and upsetting and elongation deformation are cooperatively controlled to complete the breakdown of the rod:

[0134] The GH4720Li alloy ingot obtained in step (1) is loaded into the furnace at 300 DEG C, heated to 1210 DEG C at a rate of 10 DEG C / min, held for 50 h, and then subjected to first upsetting to obtain a first blank; wherein the deformation amount of the first upsetting is 25%.

[0135] The first blank is reheated at 1220 DEG C for 6 h, cooled to 1190 DEG C in the furnace, held for 40 h, and then subjected to first elongation to obtain a second blank; wherein the deformation amount of the first elongation is 30%.

[0136] The second blank is reheated at 1200 DEG C for 6 h, cooled to 1170 DEG C in the furnace, held for 40 h, and then subjected to second upsetting to obtain a third blank; wherein the deformation amount of the second upsetting is 25%.

[0137] The third blank is reheated at 1180 DEG C for 6 h, cooled to 1150 DEG C in the furnace, held for 40 h, and then subjected to second elongation to obtain a rod blank; wherein the deformation amount of the second elongation is 30%, and the final forging temperature is not lower than 1100 DEG C.

[0138] (3) the rod blank obtained in step (2) is heat rolled by using a hot continuous rolling mill after holding at 1175 ℃ for 7 h, to obtain a rolled rod blank; wherein the deformation of the heat rolling is 25%, and the finish rolling temperature is not lower than 1100 ℃.

[0139] (4) the rolled rod blank obtained in step (3) is free forged by using a 60000t forging press after holding at 1160 ℃ for 7 h, the deformation of the free forging is 50%, the pressing speed is 10 mm / s, the finish forging temperature is not lower than 1100 ℃, the rolled rod blank is hard packed by using asbestos and steel sleeve before reheating, the thickness of the asbestos is 12 mm, the thickness of the steel sleeve is 2.5 mm, and the diameter of the rolled rod blank is 250 mm.

[0140] (5) the free forged blank obtained in step (4) is subjected to a microstructure regulating pretreatment to obtain a free forged blank; wherein the microstructure regulating pretreatment specifically comprises: holding at 1170 ℃ for 5 h, then cooling to 1130 ℃ at a speed of 6.5 ℃ / min, holding for 20 h, and then cooling to room temperature at a speed of 3.5 ℃ / min.

[0141] (6) the free forged blank obtained in step (5) is die forged by using a 60000t forging press after holding at 1160 ℃ for 7 h, wherein the deformation of the die forging is 30%, the pressing speed is 10 mm / s, the finish forging temperature is not lower than 1100 ℃, the free forged blank is hard packed by using asbestos and steel sleeve before reheating, the die is preheated to make the temperature of the die not lower than 500 ℃ before die forging, the thickness of the asbestos is 12 mm, the thickness of the steel sleeve is 2.5 mm, and the diameter of the free forged blank is 250 mm.

[0142] (7) the die forged blank obtained in step (6) is subjected to a solid solution treatment; wherein the solid solution treatment specifically comprises: loading into a furnace at 550 ℃, heating to 1160 ℃ at a speed of 10 ℃ / min, holding for 5 h, and then air cooling to room temperature; then loading into a furnace at 600 ℃, heating to 1190 ℃ at a speed of 10 ℃ / min, holding for 5 h, and then air cooling to room temperature.

[0143] (8) the die forged blank obtained in step (7) is subjected to an aging treatment to obtain a GH4720Li alloy forged piece; wherein the aging treatment specifically comprises: loading into a furnace at 350 ℃, heating to 900 ℃ at a speed of 10 ℃ / min, holding for 16 h, and then air cooling to room temperature; then loading into a furnace at 350 ℃, heating to 770 ℃ at a speed of 10 ℃ / min, holding for 16 h, and then air cooling to room temperature.

[0144] Comparative Example 1

[0145] The preparation method of the GH4720Li alloy forge piece provided by the present comparative example is basically the same as that of example 3, and the only difference is that the first solution temperature in step (7) is replaced by 1140℃, and the second solution temperature is replaced by 1150℃.

[0146] Comparative Example 2

[0147] The preparation method of the GH4720Li alloy forge piece provided by the present comparative example is basically the same as that of example 3, and the only difference is that the first aging temperature in step (8) is replaced by 780℃, and the second aging temperature is replaced by 700℃.

[0148] Comparative Example 3

[0149] The preparation method of the GH4720Li alloy forge piece provided by the present comparative example is basically the same as that of example 3, and the only difference is that the temperature of the die forging in step (6) is replaced by 1130℃, and the finish forging temperature is not lower than 950℃.

[0150] Comparative Example 4

[0151] The preparation method of the GH4720Li alloy forge piece provided by the present comparative example is basically the same as that of example 3, and the only difference is that step (5) - the microstructure regulation pretreatment is not set, that is, the forged blank obtained after the free forging of step (4) is directly die forged.

[0152] Comparative Example 5

[0153] The preparation method of the GH4720Li alloy forge piece provided by the present comparative example is basically the same as that of example 3, and the only difference is that the process parameters of the microstructure regulation pretreatment in step (5) are different.

[0154] The process parameters of the microstructure regulation pretreatment in step (5) of the present comparative example 5 are as follows: after holding at 1140℃ for 6h, the temperature is lowered to 1100℃ at a speed of 8℃ / min, and after holding for 24h, the temperature is lowered to room temperature at a speed of 5℃ / min.

[0155] Comparative Example 6

[0156] The preparation method of the GH4720Li alloy forge piece provided by the present comparative example is basically the same as that of example 3, and the only difference is that step (3) - hot continuous rolling is not set, that is, the bar blank obtained in step (2) is directly free forged.

[0157] Comparative Example 7

[0158] The preparation method of the GH4720Li alloy forge piece provided by the present comparative example is basically the same as that of example 3, and the only difference is that the upsetting and elongating process in step (2) is different.

[0159] The upsetting and elongating process in step (2) of the present comparative example 7 is as follows: the GH4720Li alloy ingot obtained in step (1) is put into a furnace at 300℃, and then heated to 1180℃ at a rate of 10℃ / min, and after holding for 50h, upsetting is performed to make the deformation amount 40%. Then, the furnace is returned to 1180℃ and holding for 8h, and then the furnace is cooled to 1160℃, and after holding for 50h, elongation is performed to make the elongation deformation amount 40%, and the final forging temperature is not lower than 1100℃.

[0160] Comparative example 8

[0161] The preparation method of the GH4720Li alloy forging provided by the present comparative example is basically the same as that of example 3, and the only difference is that the mass percentage of carbon in step (1) is replaced by 0.01%, and the mass percentage of chromium is replaced by 16.5%.

[0162] Experimental example

[0163] The room temperature tensile strength, 650℃ tensile strength, 850℃ / 300MPa endurance life and grain size of the GH4720Li alloy forgings prepared in each of the above examples and comparative examples are detected, and the detection results are shown in Table 1, which are respectively referred to ASTM E8 Standard Test Methods of Tension Testing of Metallic Materials, ASTM E21 Standard Test Methods of Tension Testing of Metallic Materials at Elevated Temperature, ASTM E139 Standard Test Methods of Creep, Creep Rupture, and Stress Rupture Testing of Metallic Materials, and ASTM E112 Standard Test Methods of Average Grain Size.

[0164] Table 1 Performance test results of each group of GH4720Li alloy forgings

[0165]

[0166] As can be seen from Table 1, by adjusting the contents of carbon and chromium and improving the processing technology, the high temperature endurance performance of the GH4720Li alloy can be significantly improved, and the grain size of the GH4720Li alloy forging prepared by the method is 2-4, the room temperature tensile strength is ≥1400MPa, the 650℃ tensile strength is ≥1280MPa, and the 850℃ / 300MPa endurance life is ≥100h.

[0167] Meanwhile, the metallographic structure diagram of the GH4720Li alloy forging prepared in example 3 is as shown in Figure 1 The metallographic structure diagram of comparative example 6 is as shown in Figure 2 .

[0168] It can be found that the grain size of the forging prepared in example 3 of the present application can reach 4, and thus the forging obtains the best mechanical properties.

[0169] Although the present application has been described and illustrated with a certain degree of particularity, it is understood that the present application has been made by way of examples only and that numerous changes in the details of execution can be made by those skilled in the art without departing from the spirit and scope of the application. It is therefore intended to cover in the appended claims all such changes and modifications that come within the scope of the application.

Claims

1. A method for producing a GH4720Li alloy forge piece, characterized in that, The method comprises the following steps: (a) sequentially performing first upsetting, first elongation, second upsetting and second elongation on a GH4720Li alloy ingot to obtain a rod blank; (b) after the rod blank is kept at 1160-1190 DEG C for 4-10 h, performing hot continuous rolling to obtain a rolled rod blank; (c) performing free forging on the rolled rod blank, and then performing structure regulation pretreatment to obtain a free forging blank; wherein the structure regulation pretreatment comprises: keeping at 1160-1180 DEG C for 4-6 h, and then keeping at 1120-1140 DEG C for 16-24 h; (d) performing die forging on the free forging blank, and then sequentially performing solid solution treatment and aging treatment to obtain a GH4720Li alloy forge piece; In the GH4720Li alloy, the content of carbon is less than 0.01% by mass percentage, and the content of chromium is 17.5%-19%.

2. The method of producing a GH4720Li alloy forging according to claim 1, characterized in that, In step (a), the GH4720Li alloy ingot is kept at 1200-1220 DEG C for 40-60 h, and then first upsetting is performed to obtain a first blank.

3. The method of producing a GH4720Li alloy forging according to claim 2, characterized in that, The deformation amount of the first upsetting is 10%-40%.

4. The method of producing a GH4720Li alloy forging according to claim 2, characterized in that, After the first blank is kept at 1220 DEG C for 4-8 h, the temperature is decreased to 1180-1200 DEG C in the furnace, and after keeping for 30-50 h, first elongation is performed to obtain a second blank.

5. The method of producing a GH4720Li alloy forging according to claim 4, characterized in that, The deformation amount of the first elongation is 20%-40%.

6. The method of producing a GH4720Li alloy forging according to claim 4, characterized in that, After the second blank is kept at 1200 DEG C for 4-8 h, the temperature is decreased to 1160-1180 DEG C in the furnace, and after keeping for 30-50 h, second upsetting is performed to obtain a third blank.

7. The method of producing a GH4720Li alloy forging according to claim 6, characterized in that, The deformation amount of the second upsetting is 10%-40%.

8. The method of producing a GH4720Li alloy forging according to claim 6, characterized in that, After the third blank is kept at 1180 DEG C for 4-8 h, the temperature is decreased to 1140-1160 DEG C in the furnace, and after keeping for 30-50 h, second elongation is performed to obtain a rod blank.

9. The method of producing a GH4720Li alloy forging according to claim 8, characterized in that, The deformation amount of the second elongation is 20%-40%.

10. The method of producing a GH4720Li alloy forging according to claim 1, characterized in that, In step (b), the deformation amount of the hot continuous rolling is 10%-40%.

11. The method of producing a GH4720Li alloy forging according to claim 1, characterized in that, In step (c), the rolled rod blank is kept at 1140-1180 DEG C for 4-10 h, and then the free forging is performed.

12. The method of producing a GH4720Li alloy forging according to claim 11, characterized in that, The deformation amount of the free forging is 40%-60%; and / or, the pressing speed of the free forging is 5-15 mm / s.

13. The method of producing a GH4720Li alloy forging according to claim 11, wherein Before heating, the rolled rod blank is subjected to hard cladding treatment using asbestos and a steel sleeve.

14. The method of producing a GH4720Li alloy forging according to claim 13, characterized in that, The thickness of the asbestos is 8-15 mm, the thickness of the steel sleeve is 2-3 mm, and the diameter of the rolled rod blank is 180-320 mm.

15. The method of making a GH4720Li alloy forging according to claim 1, wherein, In step (c), the structure regulation pretreatment specifically comprises: after keeping at 1160-1180 DEG C for 4-6 h, decreasing the temperature to 1120-1140 DEG C at a speed of 5-8 DEG C / min, keeping for 16-24 h, and then decreasing the temperature to room temperature at a speed of 2-5 DEG C / min.

16. The method of making a GH4720Li alloy forging according to claim 1, wherein In step (d), the free forging blank is kept at 1140-1180 DEG C for 4-10 h, and then die forging is performed.

17. The method of producing a GH4720Li alloy forging according to claim 16, characterized in that, The deformation amount of the die forging is 20%-40%; and / or, the pressing speed of the die forging is 5-15 mm / s.

18. The method of making a GH4720Li alloy forging according to claim 16, wherein, Before heating, the free forging blank is subjected to hard cladding treatment using asbestos and a steel sleeve.

19. The method of producing a GH4720Li alloy forging according to claim 18, characterized in that, The thickness of the asbestos is 8-15 mm, the thickness of the steel sleeve is 2-3 mm, and the diameter of the free forging blank is 200-400 mm.

20. The method of making a GH4720Li alloy forging according to claim 16, wherein, The mold is preheated before the die forging.

21. The method of making a GH4720Li alloy forging according to claim 20, wherein, The preheating temperature of the mold is not less than 500 DEG C.

22. The method of making a GH4720Li alloy forging according to claim 1, wherein, In step (d), the solution treatment comprises: holding at 1150-1170 DEG C for 4-6 h, then air cooling to room temperature, and then holding at 1180-1200 DEG C for 2-8 h, and then air cooling to room temperature.

23. The method of making a GH4720Li alloy forging according to claim 1, wherein, In step (d), the aging treatment comprises: holding at 800-950 DEG C for 8-24 h, then air cooling to room temperature, and then holding at 720-820 DEG C for 8-24 h, and then air cooling to room temperature.

24. A GH4720Li alloy forging, characterized in that, The GH4720Li alloy forging is mainly prepared by the method of any one of claims 1-8.

25. The GH4720Li alloy forging of claim 24, wherein, The grain size of the GH4720Li alloy forging is 2-4.

26. The GH4720Li alloy forging of claim 24, wherein, The tensile strength of the GH4720Li alloy forging at room temperature is greater than or equal to 1400 MPa, and the tensile strength at 650 DEG C is greater than or equal to 1280 MPa.

27. The GH4720Li alloy forging of claim 24, wherein, The 850 DEG C / 300 MPa endurance life of the GH4720Li alloy forging is greater than or equal to 100 h.

28. A gas turbine engine characterized by, The GH4720Li alloy forging is mainly prepared by the method of any one of claims 24-27.

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