Preparation method of high-strength and high-toughness GH4169 alloy bar and high-strength and high-toughness GH4169 alloy bar

Abstract

The invention provides a preparation method of a high-strength and high-toughness GH4169 alloy bar and the high-strength and high-toughness GH4169 alloy bar. According to the preparation method, a steel ingot is machined in a mode of combining a fast forging cogging technology and an extrusion technology, and the problems that when radial forging forming is adopted, due to the fact that the diameter of a bar is small and cooling is fast, the surface of a forged bar is prone to cracking, and the grain size and delta phase distribution of the cross section of the bar are uneven are solved. And meanwhile, deformation passes are reduced, and the yield and the production efficiency of the alloy bar are greatly improved. Compared with a forged bar formed by adopting fast forging and radial forging, grains from the center to the edge of the cross section of the prepared extruded bar are uniform, and no delta phase is separated out. After extrusion is finished, through standard heat treatment, the strength of the bar is equivalent to that of a forged bar, and the impact toughness is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature alloy processing, and in particular relates to a preparation method of a high-strength and high-toughness GH4169 alloy bar and a high-strength and high-toughness GH4169 alloy bar. Background Art

[0002] GH4169 nickel-based superalloy is a nickel-based superalloy strengthened by precipitation strengthening of γ" and γ' phases. It exhibits high strength and ductility, as well as good oxidation and corrosion resistance below 650°C. It is the most widely used superalloy, suitable for manufacturing components with various strength levels and requirements. It is widely used in aerospace, nuclear power, energy, electric power, and petrochemical industries.

[0003] Currently, large-size GH4169 alloy bars (Φ>120 mm) are generally formed using a combination of rapid forging and radial forging, while small-size bars (Φ<80 mm) can be hot-rolled. However, for bars with intermediate sizes, such as Φ80-Φ120 mm, radial forging can lead to surface cracking and uneven grain size and precipitate distribution across the cross-section due to the small diameter. Hot rolling, however, can lead to high rolling speeds and significant temperature rise, making microstructure control difficult and prone to substandard performance. Furthermore, current research on the microstructure and properties of GH4169 alloy bars has largely focused on high strength, oxidation resistance, and high durability. However, applications of GH4169 alloy in the aerospace, energy, and petrochemical sectors place high demands on impact toughness, while still meeting conventional mechanical and corrosion resistance requirements. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a method for preparing a high-strength and high-toughness GH4169 alloy bar and a high-strength and high-toughness GH4169 alloy bar. The GH4169 alloy bar has a specification of Φ80-Φ120 mm and has high impact toughness and mechanical properties.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a high-strength and high-toughness GH4169 alloy bar, comprising the following steps:

[0007] S1: The steel ingot is quickly forged to obtain a bar billet;

[0008] S2: After heating the billet, extrude it to the target specification, and then perform heat treatment after cooling.

[0009] Preferably, the extrusion ratio is 4-7, the extrusion speed is 210-228 mm / s, and the extrusion force is ≤3750 KN.

[0010] Preferably, the die angle of the cone die used for extrusion is 30°.

[0011] Preferably, the target specification is Φ80~Φ120 mm.

[0012] Preferably, the rapid forging process comprises the following steps:

[0013] Initially heat the steel ingot to 1100±10℃ and keep it warm for 3~4 hours;

[0014] After the steel ingot undergoes three rounds of hardening, first roughing and first drawing, the temperature is lowered to 1080±10℃ and kept warm for 2~3 hours; after two rounds of hardening and second drawing, the temperature is lowered to 1060±10℃ and kept warm for 2~3 hours; finally, after two rounds of hardening and third drawing, the temperature is lowered to 1020±10℃ for the final round, kept warm for 2~3 hours, and directly drawn to the required specifications; the deformation of the final round is controlled at 45~60%, and the stop forging temperature is ≥920℃.

[0015] Preferably, after the rapid forging, a rod blank with a diameter of Φ210-Φ246 mm is obtained.

[0016] Preferably, the heating of the rod blank includes preheating and induction heating in sequence.

[0017] Preferably, the preheating temperature is 1040-1070° C., and the preheating time is 3-4 h.

[0018] Preferably, the induction heating temperature is 1110-1130° C., and the time is 10-15 min.

[0019] Preferably, the rod blank is lubricated after being heated.

[0020] Preferably, after the extrusion is completed, straightening is performed and then cooling is performed.

[0021] Preferably, the straightening is: air-cooling the extruded sheet to ≤300°C after extrusion, and then heating it to 880-920°C for temperature correction.

[0022] Preferably, the cone mold is preheated at a temperature of 260-280° C. for 0.5-2 h.

[0023] In a second aspect, the present invention provides a GH4169 alloy bar prepared by the above preparation method.

[0024] Preferably, the impact absorption energy of the GH4169 alloy bar is above 80 J.

[0025] Preferably, the tensile strength of the GH4169 alloy bar is above 1250 MPa, and the yield strength R p0.2 Above 1100MPa.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] This invention provides a method for preparing GH4169 alloy bars. This method combines rapid forging and extrusion to process the steel ingots. This method avoids the problems of surface cracking and uneven grain size and δ-phase distribution in the cross-section of the bars caused by the small diameter and rapid cooling during radial forging. Furthermore, the method reduces the number of deformation passes, significantly improving the yield rate and production efficiency of the alloy bars.

[0028] Compared with the forged rods formed by rapid forging + radial forging, the present invention adopts an extrusion process and controls the extrusion ratio, extrusion speed, extrusion force and the angle of the extrusion die cone within an appropriate range, so that the grains from the center to the edge of the cross section of the prepared extruded rod are uniform and there is no δ phase precipitation. After the extrusion is completed, the strength of the rod (tensile strength is above 1250 MPa, yield strength R p0.2 The impact toughness is significantly improved, and the impact absorption energy is above 80 J, which is much higher than the level achievable by existing technologies (impact absorption energy is about 40 J). BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the microstructure image of the GH4169 alloy bar obtained in Example 1;

[0030] in, Figure 1 (a) corresponds to the center of the GH4169 alloy rod; Figure 1 (b) corresponds to the edge of GH4169 alloy bar;

[0031] Figure 2 This is the microstructure image of the GH4169 alloy bar obtained in Example 2;

[0032] in, Figure 2 (a) corresponds to the center of the GH4169 alloy rod; Figure 2 (b) corresponds to the edge of GH4169 alloy bar;

[0033] Figure 3 This is the microstructure image of the GH4169 alloy bar obtained in Comparative Example 1;

[0034] in, Figure 3 (a) corresponds to the center of the GH4169 alloy rod; Figure 3(b) corresponds to the edge of GH4169 alloy bar;

[0035] Figure 4 This is the microstructure image of the GH4169 alloy bar obtained in Comparative Example 2;

[0036] in, Figure 4 (a) corresponds to the center of the GH4169 alloy rod; Figure 4 (b) corresponds to the edge of the GH4169 alloy rod. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] In view of the problem that there is no effective preparation method for GH4169 alloy bars with a size of Φ80~Φ120 mm in the prior art, and that GH4169 alloy bars need to meet the requirements of conventional mechanical properties, corrosion resistance, and excellent impact toughness in special fields such as aerospace, energy, and petrochemicals, the present invention provides a method for preparing high-strength and high-toughness GH4169 alloy bars with a size of Φ80~Φ120 mm, comprising the following steps:

[0039] S1: The steel ingot is quickly forged to obtain a bar billet;

[0040] S2: After heating the billet, extrude it to the target specification, and then perform heat treatment after cooling.

[0041] According to the present invention, firstly, the steel ingot is subjected to rapid forging to obtain a rod blank.

[0042] In the present invention, the steel ingot is a raw billet obtained after vacuum induction smelting, vacuum consumable remelting, and homogenization heat treatment. The specifications of the steel ingot can be specifications well known to those skilled in the art. In some embodiments of the present invention, the specification of the steel ingot is Φ508 mm.

[0043] In the present invention, the rapid forging process comprises the following steps:

[0044] Initially heat the steel ingot to 1100±10℃ and keep it warm for 3~4 hours;

[0045] The steel ingot is subjected to three firings, followed by clamping, first roughing, and first drawing (i.e., clamping in the first firing, first roughing in the second firing, and first drawing in the third firing), and then cooled to 1080±10℃ and kept warm for 2~3 hours; then subjected to two firings for second roughing and second drawing (i.e., second roughing in the first firing, second drawing in the second firing), and then cooled to 1060±10℃ and kept warm for 2~3 hours; finally subjected to two firings for third roughing and third drawing (i.e., third roughing in the first firing, third drawing in the second firing), and then cooled to 1020±10℃ for the final firing, kept warm for 2~3 hours, and then directly drawn to the required specifications (Φ210~Φ246 mm); the deformation in the final firing is controlled at 45~60%, and the stop forging temperature is ≥920℃.

[0046] In some embodiments of the present invention, the rapid forging process comprises the following steps:

[0047] The steel ingots were forged using a high-speed forging machine to a diameter of 246 mm. Initial heating was performed at 1100°C for 4 hours. After three cycles of forging, first piercing, and drawing, the ingots were cooled to 1080°C and held for 3 hours. After two cycles of forging and drawing, the ingots were cooled to 1060°C and held for 3 hours. After two cycles of forging and drawing, the ingots were cooled to 1020°C and held for 2.5 hours. The ingots were then drawn directly to the required size (246 mm). The final deformation was controlled at 45%, and the forging temperature was stopped at 930°C.

[0048] In some other embodiments of the present invention, the rapid forging process comprises the following steps:

[0049] The steel ingots were forged using a high-speed forging machine to a diameter of 210 mm. The initial heating temperature was 1100°C, which was held for 4 hours. After three cycles of forging, initial roughing, and initial drawing, the ingots were cooled to 1080°C and held for 3 hours. After two cycles of forging and drawing, the ingots were cooled to 1060°C and held for 3 hours. After two cycles of forging and drawing, the ingots were cooled to 1020°C and held for 2 hours before being drawn directly to the target specifications. The final deformation was controlled at 60%, and the forging temperature was stopped at 920°C.

[0050] The present invention utilizes the aforementioned rapid forging process to break up the as-cast structure of conventional steel ingots and produce a fully dynamically recrystallized wrought structure. By controlling the firing temperature, deformation, and stop temperature, the grain size of the ingot after rapid forging can be controlled to between 5 and 7 grades, thereby providing a uniformly structured ingot for the extrusion process.

[0051] In the present invention, after the steel ingot is rapidly forged and the billet is obtained, the billet is preferably cut at the head and tail and cut to a length of 500 to 800 mm, such as 500 mm, 600 mm, 700 mm or 800 mm, etc. The billet is then heat treated.

[0052] In the present invention, the heating of the rod blank includes preheating and induction heating in sequence.

[0053] The preheating is preferably performed in a ring furnace at a temperature of 1040-1070°C for 3-4 hours. After exiting the ring furnace, the product is immediately transferred to an induction heating furnace for a first induction heating operation at a set temperature of 1110-1130°C for 10-15 minutes.

[0054] The above-mentioned 1040~1070℃ can be 1040℃, 1050℃, 1060℃ or 1070℃, etc., and 3~4 h can be 3 h, 3.5 h or 4 h, etc.

[0055] The above-mentioned 1110~1130℃ can be 1110℃, 1115℃, 1120℃, 1125℃, or 1130℃, and 10~15min can be 10 min, 11 min, 12 min, 13 min, 14 min or 15 min, etc.

[0056] In the present invention, the billet is heated by combining preheating and induction heating. The billet is kept at the optimal thermal deformation temperature (1040-1070°C) of the GH4169 alloy, and induction heating (1110-1130°C) is used to increase the billet surface temperature. This can prevent the problem of inability to extrude or uneven extrusion deformation due to the drop in billet surface temperature during transportation and extrusion.

[0057] After the rod blank is heated, a lubricant is preferably applied to the outer surface of the heated rod blank before extrusion. The lubricant can be a substance well known to those skilled in the art, such as glass powder.

[0058] In the present invention, the extrusion die is preferably preheated before extrusion. In some embodiments of the present invention, the extrusion die is preferably preheated using a resistance furnace, the preheating temperature is 260-280°C, such as 260°C, 265°C, 270°C, 275°C, or 280°C, and the temperature is kept for 0.5-2 hours, such as 0.5 hours, 1 hour, 1.5 hours, or 2 hours. In the present invention, the extrusion die can be any die familiar to those skilled in the art.

[0059] It should be noted that in the present invention, the extrusion speed is crucial to successful extrusion. If the extrusion speed is too low, the temperature drop of the high-temperature alloy billet will be large, resulting in increased deformation resistance and the extrusion process will become stuck (impossible extrusion). Excessive extrusion speed will cause the extrusion temperature to rise and the grain size of the extruded bar to be too large. Therefore, the present invention sets the extrusion speed to 210-228 mm / s, such as 210 mm / s, 212 mm / s, 214 mm / s, 216 mm / s, 218 mm / s, 220 mm / s, 222 mm / s, 224 mm / s, 226 mm / s, or 228 mm / s. The extrusion ratio corresponds to the amount of deformation of the bar. To ensure complete dynamic recrystallization of the bar during extrusion, the extrusion ratio should not be too low, otherwise a mixed crystal structure will be obtained. Conversely, if the extrusion ratio is too high, the deformation, extrusion force, and deformation resistance will increase, resulting in impossible extrusion. Therefore, the present invention preferably sets the extrusion ratio of extrusion to 4-7, such as 4, 4.5, 5, 5.5, 6, 6.5 or 7.

[0060] Generally, the angle of the cone die in the extrusion die can be 0°, 30°, 45°, or 60°. After screening, the present invention preferably adopts a cone die with an angle of 30° to reduce the extrusion force and ensure uniform deformation. In the present invention, after experimental exploration, within the allowable range of the equipment and under the premise of ensuring smooth extrusion of the billet, the extrusion force is preferably ≤3750 KN, for example, 3500~3750 KN.

[0061] In the present invention, after the extrusion is completed, the sheet is straightened and then cooled. The straightening is as follows: the sheet obtained by extrusion is air-cooled to ≤300°C after extrusion, then heated to 880-920°C for temperature calibration, and then air-cooled to room temperature after straightening.

[0062] Finally, the straightened bars are sampled for heat treatment. This heat treatment is a standard heat treatment, including solution treatment and aging. In this invention, the solution treatment is performed at 950-980°C for 10-30 minutes, followed by air cooling. The aging treatment is performed at 720±10°C for 8 hours, followed by furnace cooling at 50°C / hour to 620±10°C, followed by 8 hours of holding, and air cooling.

[0063] After the above heat treatment is completed, the obtained bar samples are subjected to microstructure and performance tests.

[0064] After testing, the tensile strength of the obtained rods by combining the above-mentioned rapid forging and extrusion process of the present invention and controlling the extrusion process parameters is above 1250 MPa and the yield strength R p0.2 It is above 1100 MPa, which is equivalent to that of forged rods, and the impact absorption energy is above 80 J. Compared with existing technologies, the impact toughness has been greatly improved.

[0065] To further illustrate the present invention, the following examples are provided for detailed description: The steel ingot is obtained through vacuum induction smelting, vacuum consumable remelting, and homogenization heat treatment.

[0066] The room temperature tensile strength Rm and yield strength R of the following bars p0.2 , elongation A, and section shrinkage are measured in accordance with GB / T228.1, and impact absorption energy is measured in accordance with GB / T229.

[0067] Example 1

[0068] The present invention provides a method for preparing a GH4169 alloy bar with a diameter of Φ120 mm, comprising the following steps:

[0069] A. The steel ingots that have been subjected to vacuum induction smelting, vacuum consumable remelting, and homogenization heat treatment are used as the original billet. The ingot specification is Φ508 mm.

[0070] B. The steel ingot is forged using a high-speed forging machine to a diameter of 246 mm. The initial heating temperature is 1100°C, held for 4 hours. After three cycles of forging, initial roughing, and initial drawing, the ingot is cooled to 1080°C and held for 3 hours. After two cycles of forging and drawing, the ingot is cooled to 1060°C and held for 3 hours. After two cycles of forging and drawing, the ingot is cooled to 1020°C and held for 2.5 hours before being drawn directly to the target specification. The final deformation is controlled at 45%, and the forging stop temperature is 930°C.

[0071] C. Cut the head and tail of the rod and cut it to a length of 600 mm.

[0072] D. Preheat the extrusion die. Use a resistance furnace to preheat the extrusion die to 280°C and keep it warm for 1 hour.

[0073] E. Billet heating: Preheat the billet in a ring furnace at 1070°C for 4 hours. Immediately after exiting the ring furnace, transfer the billet to an induction heating furnace for a primary induction heating session at 1120°C for 15 minutes.

[0074] F. Lubrication: Apply glass powder lubricant to the outer surface of the induction heated rod.

[0075] G. Extrusion. A 4500-ton extruder was used to extrude the billet to the target specifications, with an extrusion ratio of 4.2. The extrusion die used was a conical die with a 30° die angle and H13 material. The extrusion speed was 210 mm / s, and the extrusion force was 3680 kN.

[0076] H. Straightening: After extrusion, the bar is air-cooled to ≤300℃, then heated to 900℃ for temperature calibration, and then air-cooled to room temperature after straightening.

[0077] I. Heat Treatment. Samples of the bar were solution treated and aged, followed by microstructure and performance testing. The solution treatment process was: 980°C for 30 minutes, followed by air cooling. The aging process was: 720°C for 8 hours, furnace cooling at 50°C / hour to 620°C, followed by 8 hours of temperature control, and air cooling.

[0078] The GH4169 alloy rod prepared in this embodiment has a uniform structure, a core grain size of 5.5, and an edge grain size of 6.5. Figure 1 (Photographed using a microscope). The room temperature tensile strength of the bar is Rm = 1297 MPa, and the yield strength is R p0.2 =1167 MPa, elongation A=19.5%, section shrinkage Z=34.5%, impact absorption energy KV2=86 J.

[0079] Example 2

[0080] The present invention provides a method for preparing a GH4169 alloy bar with a diameter of Φ80 mm, comprising the following steps:

[0081] A. The steel ingots that have been subjected to vacuum induction smelting, vacuum consumable remelting, and homogenization heat treatment are used as the original billet. The ingot specification is Φ508 mm.

[0082] B. The steel ingot is forged using a high-speed forging machine to a diameter of 210 mm. The initial heating temperature is 1100°C, held for 4 hours. After three cycles of forging, initial roughing, and initial drawing, the ingot is cooled to 1080°C and held for 3 hours. After two cycles of forging and drawing, the ingot is cooled to 1060°C and held for 3 hours. After two cycles of forging and drawing, the ingot is cooled to 1020°C and held for 2 hours before being drawn directly to the target specification. The final deformation is controlled at 60%, and the forging stop temperature is 920°C.

[0083] C. Cut the head and tail of the rod and cut it to a length of 600 mm.

[0084] D. Preheat the extrusion die. Use a resistance furnace to preheat the extrusion die to 260°C and keep it warm for 1 hour.

[0085] E. Billet heating: Preheat the billet in a ring furnace at 1070°C for 3 hours. Immediately after exiting the ring furnace, transfer the billet to an induction heating furnace for a primary induction heating session at 1110°C for 10 minutes.

[0086] F. Lubrication: Apply glass powder lubricant to the outer surface of the induction heated rod.

[0087] G. Extrusion. A 4500-ton extruder was used to extrude the billet to the target specifications, with an extrusion ratio of 6.8. The extrusion die used was a tapered die with a 30° die angle and H13 material. The extrusion speed was 228 mm / s, and the extrusion force was 3630 kN.

[0088] H. Straightening: After extrusion, the bar is air-cooled to ≤300℃, then heated to 900℃ for temperature calibration, and then air-cooled to room temperature after straightening.

[0089] I. Heat Treatment. Samples of the bar material were solution treated and aged, followed by microstructure and performance testing. The solution treatment process was: 950°C for 30 minutes, followed by air cooling. The aging process was: 720°C for 8 hours, furnace cooling at 50°C / hour to 620°C, followed by 8 hours of temperature control, and air cooling.

[0090] The GH4169 alloy rod prepared in this embodiment has uniform structure, the core grain size is level 6, the edge grain size is level 7, and its microstructure is shown in FIG. Figure 2 The room temperature tensile strength of the bar is Rm=1288 MPa, and the yield strength is R p0.2 =1151 MPa, elongation A=20%, cross-sectional shrinkage Z=35%, impact absorption energy KV2=81 J.

[0091] Comparative Example 1

[0092] This comparative example provides a method for preparing a GH4169 alloy bar with a diameter of Φ120 mm, and the steps are as follows:

[0093] A. The steel ingots that have been subjected to vacuum induction smelting, vacuum consumable remelting, and homogenization heat treatment are used as the original billet. The ingot specification is Φ508 mm.

[0094] B. The steel ingots were forged into 240 mm octagonal ingots using a high-speed forging machine. The initial heating temperature was 1100°C, held for 4 hours. After three cycles of forging, initial roughing, and initial drawing, the ingots were cooled to 1080°C and held for 3 hours. After two cycles of forging and drawing, the ingots were cooled to 1060°C and held for 3 hours. After two cycles of forging and drawing, the ingots were cooled to 1020°C and held for 2.5 hours. The ingots were then drawn directly to the target specifications. The final deformation was controlled at 45%, and the forging temperature was stopped at 930°C.

[0095] C. Radial forging: Radial forging is heated to 1010℃, kept at this temperature for 3 hours, and forged to the target specifications in two passes.

[0096] D. Heat Treatment. Samples of the bar material were subjected to solution and aging treatments, followed by microstructure and performance testing. The solution treatment process was: 980°C for 30 minutes, followed by air cooling; the aging process was: 720°C for 8 hours, furnace cooling at 50°C / hour to 620°C, followed by 8 hours of holding, and air cooling.

[0097] In this comparative example, GH4169 alloy bars were prepared. The grain size of the core was level 7, the grain size of the edge was level 9, there was no δ phase in the core, but δ phase precipitated at the edge. The δ phase was unevenly distributed from the core to the edge. The microstructure was Figure 3 The room temperature tensile strength of the bar is Rm=1369 MPa, and the yield strength is R p0.2 =1178 MPa, elongation A=21%, section shrinkage Z=36%, impact absorption energy KV2=38J.

[0098] Comparative Example 2

[0099] This comparative example provides a method for preparing a GH4169 alloy bar with a diameter of Φ120 mm, and the steps are as follows:

[0100] A. The steel ingots that have been subjected to vacuum induction smelting, vacuum consumable remelting, and homogenization heat treatment are used as the original billet. The ingot specification is Φ508 mm.

[0101] B. The steel ingot is forged using a high-speed forging machine to a diameter of 210 mm. The initial heating temperature is 1100°C, held for 4 hours. After three cycles of forging, initial roughing, and initial drawing, the ingot is cooled to 1080°C and held for 3 hours. After two cycles of forging and drawing, the ingot is cooled to 1060°C and held for 3 hours. After two cycles of forging and drawing, the ingot is cooled to 1020°C and held for 2 hours before being drawn directly to the target specification. The final deformation is controlled at 60%, and the forging stop temperature is 920°C.

[0102] C. Cut the head and tail of the rod and cut it to a length of 600 mm.

[0103] D. Preheating of extrusion die: Use resistance furnace to preheat the extrusion die to 280℃ and keep it warm for 1 hour.

[0104] E. Billet heating: Preheat the billet in a ring furnace at 1070°C for 4 hours. Immediately after exiting the ring furnace, transfer the billet to an induction heating furnace for a primary induction heating session at 1140°C for 15 minutes.

[0105] F. Lubrication: Apply glass powder lubricant to the outer surface of the induction heated rod.

[0106] G. Extrusion. A 4500-ton extruder was used to extrude the billet to the target specifications, with an extrusion ratio of 3.1. The extrusion die used was a conical die with a 30° die angle and H13 material. The extrusion speed was 236 mm / s, and the extrusion force was 3570 kN.

[0107] H. Straightening: After extrusion, the bar is air-cooled to ≤300℃, then heated to 900℃ for temperature calibration, and then air-cooled to room temperature after straightening.

[0108] I. Heat Treatment. Samples of the bar were solution treated and aged, followed by microstructure and performance testing. The solution treatment process was: 980°C for 30 minutes, followed by air cooling. The aging process was: 720°C for 8 hours, furnace cooling at 50°C / hour to 620°C, followed by 8 hours of temperature control, and air cooling.

[0109] The GH4169 alloy rod prepared in this embodiment has a uniform structure, a core grain size of 5.5, and an edge grain size of 6.5. Figure 4 The room temperature tensile strength of the bar is Rm=1260 MPa, and the yield strength is R p0.2 =1120 MPa, elongation A=18.5%, section shrinkage Z=32%, impact absorption energy KV2=43 J.

[0110] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing high-strength and high-toughness GH4169 alloy bars, characterized in that: The following steps are involved: S1: The steel ingot is quickly forged to obtain a bar billet; S2: After heating the billet, it is extruded to the target specification and then heat treated after cooling; The extrusion ratio of the extrusion is 4-7, the extrusion speed is 210-228 mm / s, and the extrusion force is ≤3750 KN.

2. The preparation method according to claim 1, characterized in that The die angle of the cone die used in the extrusion is 30°; The target specification is Φ80~Φ120 mm.

3. The preparation method according to claim 1 or 2, characterized in that The rapid forging process comprises the following steps: Initially heat the steel ingot to 1100±10℃ and keep it warm for 3~4 hours; After the steel ingot undergoes three rounds of hardening, first roughing and first drawing, the temperature is lowered to 1080±10℃ and kept warm for 2~3 hours; after two rounds of hardening and second drawing, the temperature is lowered to 1060±10℃ and kept warm for 2~3 hours; finally, after two rounds of hardening and third drawing, the temperature is lowered to 1020±10℃ for the final round, kept warm for 2~3 hours, and directly drawn to the required specifications; the deformation of the final round is controlled at 45~60%, and the stop forging temperature is ≥920℃.

4. The preparation method according to claim 1, characterized in that After the rapid forging, a bar blank with a diameter of Φ210-Φ246 mm is obtained.

5. The preparation method according to claim 1, characterized in that The heating of the rod blank includes preheating and induction heating in sequence; The preheating temperature is 1040-1070°C and the time is 3-4 hours; The induction heating temperature is 1110-1130° C., and the time is 10-15 min.

6. The preparation method according to claim 1, characterized in that After the rod blank is heated, the rod blank is lubricated.

7. The preparation method according to claim 1, characterized in that After the extrusion is completed, straightening is performed and then cooling is performed; The straightening is as follows: air cooling the extruded sheet to ≤300°C after extrusion, and then heating it to 880-920°C for temperature correction.

8. The preparation method according to claim 2, characterized in that The cone mold is preheated at a temperature of 260-280° C. for 0.5-2 h.

9. GH4169 alloy bar prepared by the preparation method according to any one of claims 1 to 8.

10. The GH4169 alloy bar according to claim 9, characterized in that: The impact absorption energy of the GH4169 alloy bar is above 80 J; The tensile strength of the GH4169 alloy bar is above 1250 MPa, and the yield strength R p0.2 Above 1100 MPa.

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