Method for reducing surface defects of deformed high-temperature alloy hot extrusion pipe

Abstract

The invention provides a method for reducing surface defects of a wrought high-temperature alloy hot extrusion pipe, and relates to the technical field of metal hot pressure machining, and the method comprises the following steps: preparing a ton-level wrought high-temperature alloy ingot into a pipe blank, and then carrying out hot extrusion treatment on the pipe blank; wherein the extrusion ratio ranges from 4.2 to 5.5, and the extrusion rate ranges from 20 mm / s to 50 mm / s. According to the method, the alloy ingot is prepared into the pipe blank before blank manufacturing, the defects of looseness, segregation, air holes and the like existing in the structure of the alloy ingot are eliminated, and the defects are prevented from being pressed into the extrusion blank in the direct extrusion process, so that cracks or non-uniform performance is caused; and furthermore, reasonable hot extrusion parameters are set, namely the extrusion ratio is 4.2-5.5, and the extrusion rate is 20-50 mm / s, so that the fluidity of the blank is ensured, and formation of surface orange peel, streamlines, folding and other defects is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal pressure processing, and particularly relates to a method for reducing surface defects of hot extruded pipes of deformation high-temperature alloy. BACKGROUND

[0002] Extrusion is an important method of metal hot working, and its deformation principle is to apply external force to a blank placed in an extrusion cylinder, so that the plastic deformation of the blank flows out of a specific die hole to obtain the required cross-sectional shape and size, and rods, pipes and special-shaped materials can be prepared. Deformation high-temperature alloy is a solid solution strengthened nickel-chromium-cobalt-molybdenum alloy and has excellent high-temperature strength and oxidation resistance. Due to very high thermal strength, large deformation resistance, and the need for considerable processing force in the process of thermal deformation, the extrusion temperature range of this kind of difficult-to-deform high-temperature alloy is narrow, and the alloy deformation capacity is weak, resulting in that defects are very sensitive to extrusion parameters and the technical difficulty is relatively large.

[0003] The existing related technologies focus on the extrusion of small-caliber deformation high-temperature alloy pipes. Since the composition and organization uniformity of small billets is more uniform than that of large ingots, a large extrusion ratio (extrusion ratio 8.9) and a faster extrusion rate (260-300 mm / s) can be used without defects. There are also related technologies for extruding difficult-to-deform high-temperature alloys using a larger extrusion ratio and extrusion rate.

[0004] However, due to the slow solidification speed of tonnage alloy ingots, the composition and organization uniformity of small ingots is poor, and the deformation high-temperature alloy has very high thermal strength and large deformation resistance, resulting in a very narrow deformation window of the alloy. In the process of thermal deformation, the existing extrusion method is prone to surface defects. SUMMARY

[0005] Therefore, the present application provides a method for reducing surface defects of hot extruded pipes of deformation high-temperature alloy, which can solve the problem of easy defects on the surface during extrusion in the prior art.

[0006] In order to solve the above problems, the first aspect of the present application provides a method for reducing surface defects of hot extruded pipes of deformation high-temperature alloy, comprising the following steps:

[0007] Preparation of tonnage deformation high-temperature alloy ingots into pipe blanks, and then hot extrusion treatment of the pipe blanks;

[0008] Wherein, the extrusion ratio is 4.2-5.5, and the extrusion rate is 20-50 mm / s.

[0009] Further, the maximum extrusion force F in the extrusion treatment satisfies the following formula:

[0010] ;

[0011] Wherein, F is the maximum extrusion force, unit: kN; D is the diameter of the extrusion cylinder, unit: cm; d is the diameter of the mandrel, unit: cm; σ is the deformation resistance related to the extrusion rate and temperature, unit: MPa; λ is the extrusion ratio; L is the length of the pipe blank, unit: cm.

[0012] Further, before the step of the hot extrusion treatment, further comprising:

[0013] carrying out a heat preservation treatment on the pipe blank;

[0014] Further, the temperature of the heat preservation treatment is 1150-1230℃; the time of the heat preservation treatment is ≥ the wall thickness of the pipe blank x 2 min / mm; wherein, the time of the heat preservation treatment is in unit of min, and the wall thickness of the pipe blank is in unit of mm.

[0015] Further, a glass powder is coated on the surface of the pipe blank after the heat preservation treatment; preferably, the particle size of the glass powder is 80-120 mesh.

[0016] Further, the step of preparing the tonnage deformed high-temperature alloy ingot into a pipe blank comprises:

[0017] carrying out a forging treatment on the tonnage deformed high-temperature alloy ingot, so that the columnar crystal structure in the tonnage deformed high-temperature alloy ingot is transformed into an equiaxed crystal structure, to obtain an alloy forged blank;

[0018] then sequentially carrying out a heat preservation treatment, a upsetting treatment and a punching treatment on the alloy forged blank, to obtain the pipe blank.

[0019] Further, the content of non-metallic impurities O in the tonnage deformed high-temperature alloy ingot is ≤20 ppm, the content of N is ≤35 ppm, and the content of H is ≤3 ppm; and / or

[0020] the tonnage deformed high-temperature alloy ingot is a 3-6 ton deformed high-temperature alloy ingot; and / or

[0021] the tonnage deformed high-temperature alloy ingot is obtained by sequentially carrying out vacuum induction melting and vacuum consumable remelting on alloy raw materials.

[0022] Further, after the step of the extrusion treatment, an extrusion blank is obtained, and a cooling treatment is carried out on the extrusion blank.

[0023] Further, the cooling treatment is in the form of water cooling;

[0024] Preferably, the time of the cooling treatment is ≥30 min; until the extrusion blank is cooled to ≤100℃ and is taken out.

[0025] To achieve the above object, the second aspect of the present application provides a deformed high-temperature alloy hot extruded pipe, which is prepared by the method for reducing surface defects of the deformed high-temperature alloy hot extruded pipe, and has no orange peel, streamline, fold on the surface, the carbide at the grain boundary is discontinuously distributed, and the size of the carbide is less than 3 μm. By using the above technical solution of the present application, at least the following beneficial effects are achieved:

[0026] 1. The present application provides a method for reducing surface defects of a deformed high-temperature alloy hot extruded pipe, comprising the following steps: preparing a tonnage deformed high-temperature alloy ingot into a pipe blank, and then performing hot extrusion treatment on the pipe blank; wherein the extrusion ratio is 4.2-5.5, and the extrusion rate is 20-50 mm / s. The present application sets reasonable hot extrusion parameters, i.e. the extrusion ratio is 4.2-5.5, and the extrusion rate is 20-50 mm / s, to ensure the flowability of the blank, especially the surface metal cannot appear flow discontinuity, and reduce the formation of surface defects such as orange peel, streamline, fold, etc.

[0027] 2. Further, the maximum extrusion force F in the extrusion treatment satisfies ; wherein F is the maximum extrusion force, in kN; D is the diameter of the extrusion cylinder, in cm; d is the diameter of the mandrel, in cm; σ is the deformation resistance related to the extrusion rate and temperature, in MPa; λ is the extrusion ratio; and L is the length of the pipe blank, in cm. The maximum extrusion force F can further ensure the flowability of the blank and reduce the formation of surface defects such as orange peel, streamline, fold, etc.

[0028] 3. The present application performs forging treatment on the tonnage deformed high-temperature alloy ingot, so that the columnar crystal structure in the tonnage deformed high-temperature alloy ingot is transformed into equiaxed crystal structure, to obtain an alloy forged blank; and then the alloy ingot is prepared into a pipe blank, which can eliminate defects such as looseness, segregation, pores, etc. existing in the structure of the alloy ingot, and avoid that these defects are pressed into the extruded blank when directly extruded, resulting in cracks or uneven performance.

[0029] 4. The present application performs cooling treatment on the extruded blank, preferably adopts water cooling, and the cooling treatment time is ≥30 min; and the extruded blank is taken out until it is cooled to ≤100℃. The water cooling after extrusion can ensure a fast cooling rate, ensure that the high-temperature extruded pipe rapidly passes through the carbide precipitation temperature range, reduce the precipitation of grain boundary carbide, and lay a good foundation for the uniformity of the subsequent cold rolling of the pipe. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. The drawings in the following description are only exemplary, and for those skilled in the art, other drawings can be derived from the provided drawings without creative labor.

[0031] Figure 1 is a picture of the 617 alloy hollow pipe after hot extrusion in Example 1;

[0032] Figure 2 is a picture of the 617 alloy hollow pipe after hot extrusion in Comparative Example 1;

[0033] Figure 3 is a micrograph of the alloy ingot in Example 1;

[0034] Figure 4 is a micrograph of the pipe blank after heat preservation treatment in Example 1;

[0035] Figure 5 is a corresponding value of the deformation resistance σ of the 617 alloy at different temperatures and extrusion rates;

[0036] Figure 6 is a micrograph of the head of the 617 alloy hollow pipe after hot extrusion in Example 1;

[0037] Figure 7 is a micrograph of the tail of the 617 alloy hollow pipe after hot extrusion in Example 1;

[0038] Figure 8 is a microstructure diagram of the 617 alloy hollow pipe after hot extrusion in Example 1;

[0039] Figure 9 is a microstructure diagram of the 617 alloy hollow pipe after hot extrusion in Comparative Example 1;

[0040] Figure 10 is a microstructure diagram of the cracking of the 617 alloy hollow pipe after hot extrusion in Comparative Example 1. DETAILED DESCRIPTION

[0041] To further illustrate the technical means and effects taken by the present application to achieve the predetermined purposes, the specific embodiments, structures, features and effects according to the present application are described in detail below in combination with the drawings and preferred embodiments. In the following description, different "an embodiment" or "embodiments" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0042] The present application aims at the problem that the surface of a 3-6 ton deformed high-temperature alloy ingot large-diameter thick-wall hot extruded pipe (a hot extruded pipe with an outer diameter greater than 500 mm and a wall thickness greater than 60 mm after extrusion) is prone to defects, and provides a method for reducing surface defects of a deformed high-temperature alloy hot extruded pipe, comprising the following steps:

[0043] A ton-level deformed high-temperature alloy ingot is prepared into a pipe blank, and then the pipe blank is subjected to hot extrusion treatment;

[0044] wherein the extrusion ratio is 4.2-5.5 and the extrusion rate is 20-50 mm / s.

[0045] The specific steps are as follows: first, 3-6 tons of wrought superalloy ingots are forged and punched to form a pipe blank with an outer diameter of 900-930 mm and an inner diameter of 300-500 mm; wherein the forging process ensures the uniformity of the composition and organization; the microstructure of the forged ingot after forging is equiaxed crystal, and the grain boundary has no coarse continuous carbide precipitated; the forged ingot has no macroscopic defects such as segregation (e.g. uneven grains, corrosion pits), shrinkage holes, etc.; the non-metallic impurities O content in the tonnage wrought superalloy ingot is ≤20 ppm, the N content is ≤35 ppm, and the H content is ≤3 ppm.

[0046] Then the punched pipe blank is heated to 1150-1230℃ for heat preservation treatment; wherein the temperature deviation satisfies ±10℃, and the heat preservation time is determined according to the wall thickness of the blank, satisfying the calculation of heat preservation time (min) ≥ wall thickness (mm) × 2 (min / mm), wherein 2 min / mm means that the blank needs 2 min of heat preservation time for every 1 mm of wall thickness, and satisfies the requirement of ≥6h, so as to ensure that the blank (pipe blank) temperature is uniform, the grain boundary carbide is fully dissolved, the alloy is softened, and has good thermal plasticity.

[0047] After discharging, the inner and outer surfaces of the blank are coated with a glass lubricant to reduce the friction between the blank and the die during hot extrusion, and to ensure the flowability of the blank during deformation.

[0048] Then the blank is transported to a ten-ton extruder for hot extrusion, and by setting reasonable hot extrusion parameters, i.e. extrusion ratio 4.2-5.5, maximum extrusion force 36,000 tons, and extrusion rate 20-50 mm / s, the flowability of the blank is ensured, especially the surface metal cannot appear discontinuous flow, and the formation of defects such as surface orange peel, streamline, folding, etc. is reduced.

[0049] After extrusion, the rough pipe (extruded blank) is immediately placed in a cooling water bucket for cooling, and the cooling time is ≥30 min, until the pipe blank is cooled to ≤100℃ and taken out, to ensure that the inner and outer surface quality of the extruded rough pipe is good.

[0050] Based on the above method, the extruded blank (extruded rough pipe) obtained by the present application has no defects such as orange peel, streamline, folding, etc. on the surface, and no coarse carbide precipitates at the grain boundary, the size of the carbide is <3 μm, and the carbide is sporadically distributed.

[0051] In some embodiments, the maximum extrusion force F in the extrusion process satisfies the following formula:

[0052] ;

[0053] Wherein, F is the maximum extrusion force, unit is kN; D is the diameter of the extrusion cylinder, unit is cm; d is the diameter of the mandrel, unit is cm; σ is the deformation resistance related to the extrusion rate and temperature, unit is MPa; λ is the extrusion ratio; L is the length of the tube blank, unit is cm.

[0054] The extrusion ratio is the ratio of the cross-sectional area of the extrusion cylinder cavity to the total cross-sectional area of the extruded product, reflecting the degree of deformation of the metal in the extrusion process.

[0055] In some embodiments, the step of preparing the tonnage deformed high-temperature alloy ingot into a tube blank specifically comprises:

[0056] Step 1) sequentially performing vacuum induction melting and vacuum consumable remelting on the alloy raw material to obtain a 3-6 ton deformed high-temperature alloy ingot; then performing forging treatment on the tonnage deformed high-temperature alloy ingot to convert the columnar crystal structure in the tonnage deformed high-temperature alloy ingot into an equiaxed crystal structure, and obtaining an alloy forge blank;

[0057] Wherein, the content of non-metallic impurities O in the tonnage deformed high-temperature alloy ingot is ≤20 ppm, the content of N is ≤35 ppm, and the content of H is ≤3 ppm, so as to avoid microcracking caused by non-metallic inclusions, and the four types of coarse and fine inclusions A, B, C and D in the alloy ingot are all ≤1.5 levels; titanium-carbonitride is rated according to B level and D level non-metallic inclusions, both ≤2.5 levels;

[0058] The specific parameters of the forging treatment include a pre-forging ingot heating temperature of about 1200°C, a finish-forging temperature greater than 850°C, and a forging ratio greater than 4. Wherein, the forging ratio greater than 4 ensures the crushing of coarse casting dendritic structure, the dendritic structure becomes equiaxed crystal structure, the grain boundary does not precipitate coarse continuous carbide, and the forged ingot has no macroscopic defects such as segregation (e.g. uneven grains, corrosion pits), shrinkage holes, etc.

[0059] Step 2) After forging breakdown, the oxide skin is removed by mechanical processing, and the diameter of the alloy forge blank after mechanical processing is 650-900 mm; then it is loaded into a heating furnace for heat preservation treatment, the surface of the alloy forge blank after heat preservation treatment is coated with glass powder, and then the alloy forge blank coated with glass powder is placed in a ten-ton or more blank making machine to perform closed upsetting filling mold, and then punching needle is used to complete punching treatment.

[0060] The temperature of the heat preservation treatment is 1150-1230℃; the time of the heat preservation treatment is greater than or equal to the radius of the alloy ingot multiplied by 2; the elongation of the alloy ingot after the heat preservation treatment is greater than or equal to 70%; and the high-temperature heating alloy is mainly expected to have good plasticity and low deformation resistance to facilitate forging deformation. The lower limit of the temperature, 1150℃, is mainly selected according to the reduction of the deformation resistance, the guarantee of the alloy yield strength being less than or equal to 120MPa, the improvement of the alloy plasticity, and the guarantee of the alloy elongation being greater than or equal to 70%. The upper limit of the temperature, 1230℃, is mainly selected to prevent overburning and must be less than 100℃ below the solidus of the alloy. Due to the high-speed deformation, a large thermal effect is generated in the alloy ingot, and the deformation cracking caused by the grain boundary liquefaction due to overburning is prevented.

[0061] The glass powder is suitable for an extrusion temperature of 1150-1200℃, and the main component of the glass powder is SiO2, and the particle size is 80-120 mesh. The glass powder is used to reduce the friction coefficient between the ingot and the punching needle during the deformation process, which is beneficial to the high-temperature deformation flow of the ingot. The glass powder is used to ensure the uniformity of the temperature of the pipe blank, the full dissolution of the grain boundary carbide, the softening of the alloy, and the good thermal plasticity of the alloy by heat preservation treatment of the pipe blank. Then, the pipe blank is subjected to hot extrusion, and the surface defects of the extruded pipe are reduced by setting appropriate extrusion parameters. After the extrusion is completed, the pipe is subjected to water cooling until the pipe blank is cooled to less than or equal to 100℃ and is taken out. The water cooling method is selected to achieve a faster cooling speed, avoid the abnormal growth of the grain boundary carbide, and further ensure the good quality of the inner and outer surfaces of the extruded pipe.

[0062] Based on the above method, the extruded pipe obtained by the method has no orange peel, streamline, folding and other defects on the surface, no coarse carbide precipitates at the grain boundary, and the grain boundary carbide is discontinuously distributed and has a size less than 3μm.

[0063] The application will be further described below in combination with specific examples and comparative examples.

[0064] Example 1

[0065] The application provides a hot extrusion method of 617 alloy, which comprises the following steps:

[0066] The 4.2-ton deformed high-temperature alloy ingot (617 alloy ingot) obtained by vacuum induction melting and vacuum consumable remelting is forged, the ingot heating temperature before forging is about 1200℃, the final forging temperature is greater than 850℃, the forging ratio is greater than 4, the microstructure of the forged ingot after forging is equiaxed crystal, no coarse continuous carbide is precipitated at the grain boundary, and the forged ingot has no macroscopic defects such as segregation (e.g., uneven grains, corrosion pits) and shrinkage holes. Then, the hot extrusion blank (pipe blank) with an outer diameter of 920mm and an inner diameter of 445mm is prepared by punching.

[0067] The hot extrusion billet is heated to 1200℃ for 12h (the holding time 12h > (920-445) (mm) / 2 x 2 (min / mm)), and the billet temperature deviation is ≤10℃;

[0068] The billet is taken out by the mechanical hand, and the inner and outer surfaces are coated with glass powder suitable for the extrusion temperature of 1150-1200℃ and the particle size of 80-120 mesh; then the billet is quickly transported to the extruder, and the extrusion ratio is 5.12 (corresponding to the extrusion die (extrusion cylinder diameter D) of 950mm and the core rod diameter d of 430mm), the extrusion rate is 40mm / s, the deformation resistance σ is 80Mpa at the temperature of 1200℃ and the extrusion rate of 40mm / s, the length L of the pipe billet is 940mm (0.94m), and the maximum extrusion force F in the extrusion process is 302MN (3.02 million tons of force);

[0069] The hollow pipe is transported to the flowing cooling water bucket within 3min after the extrusion is completed, and the cooling time is 60min until the hollow pipe is cooled to ≤100℃ and taken out.

[0070] In this embodiment, the tonnage deformation high-temperature alloy ingot (617 alloy ingot) is a solid solution strengthened nickel-chromium-cobalt-molybdenum alloy, in which the non-metallic impurities O content is ≤20ppm, the N content is ≤35ppm, and the H content is ≤3ppm.

[0071] The extrusion billet (deformation high-temperature alloy hollow pipe, 617 alloy hollow pipe) obtained in this embodiment is as shown in Figure 1 It can be seen that there is no orange peel, streamline, folding and other defects on the surface. Among them, the micrograph of the alloy ingot used is as shown in Figure 3 It can be seen that the alloy ingot is a uniform equiaxed crystal organization, there is no macrosegregation, and no coarse continuous carbide precipitates on the grain boundary; the microstructure of the pipe billet after holding is taken out is as shown in Figure 4 It can be seen that the carbide on the grain boundary is dissolved; the micrographs of the head and tail of the deformation high-temperature alloy hollow pipe after extrusion are as shown in Figure 6 and 7 It can be seen that the grains of the alloy hollow pipe head and tail are uniform, in which the grain size of the head is 3.0 grade, and the grain size of the tail is 5.0 grade; the overall microstructure of the deformation high-temperature alloy hollow pipe after extrusion is as shown in Figure 8 It can be seen that there is no coarse carbide on the grain boundary, the carbide is sporadically distributed, the grain boundary carbide is discontinuously distributed, and the size is <3μm.

[0072] Comparative Example 1

[0073] This comparative example provides a hot extrusion method of 617 alloy, which includes the following steps:

[0074] The 5.0-ton deformed high-temperature alloy ingot, which was vacuum induction melting and vacuum self-consumption remelting, was conventionally forged and punched to produce a hot extruded billet with an outer diameter of 920mm and an inner diameter of 445mm.

[0075] Heat the billet to 1200℃ and hold for 12 hours; the billet temperature deviation should be ≤10℃.

[0076] A robotic arm is used to remove the billet from the furnace, and the inner and outer surfaces are coated with glass powder of 80-120 mesh suitable for extrusion temperatures of 1150-1200℃. The billet is quickly transferred to the extruder, using an extrusion ratio of 5.9 (greater than 5.5) (corresponding to an extrusion die diameter (extrusion cylinder diameter D) of 950mm and a mandrel diameter d of 440mm), an extrusion speed of 50mm / s, a deformation resistance σ of 83MPa at 1200℃ and an extrusion speed of 50mm / s, a billet length L of 1100mm (1.10m), and a maximum extrusion pressure of 339MN (33,900 tons of force).

[0077] Three minutes after extrusion, the raw tube is transferred to a flowing cooling water tank and cooled for 60 minutes until it is cooled to ≤100℃ before being removed.

[0078] The extruded billets (deformed high-temperature alloy blanks, 617 alloy blanks) obtained in this comparative example are as follows: Figure 2 As shown in the figure, obvious cracks are present on the surface. The microstructure diagrams of the hot-extruded deformed high-temperature alloy tube and the microstructure diagram before cracking are shown in the figures below. Figure 9 and 10 As shown, the grain size is uneven, and continuous strip-shaped carbides precipitate at the crack front.

[0079] Because 617 alloy has poor plastic deformation capacity, as the extrusion ratio increases, the resistance to the flow of the outer layer of metal from the alloy ingot ring to the die orifice also increases, leading to a greater difference in the flow velocity between the inner and outer metals and uneven deformation. The high-temperature metal outside, upon contact with the extrusion die and mandrel, cools rapidly, causing a decrease in deformation capacity. Furthermore, if the metal flow is discontinuous during extrusion, it can easily lead to surface defects such as orange peel, streamlines, and folds. Therefore, this embodiment uses a larger extrusion ratio, 5.9, to illustrate the impact of the extrusion ratio on surface quality.

[0080] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0081] The above merely describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application. The above merely describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of reducing surface defects in hot extruded pipe of a wrought superalloy, characterized by, The method comprises the following steps: a tonnage wrought superalloy ingot is prepared into a pipe blank, and then the pipe blank is subjected to hot extrusion treatment; wherein the extrusion ratio is 4.2-5.5, and the extrusion rate is 20-50 mm / s.

2. The method of reducing surface defects of a hot-extruded, wrought pipe of a wrought superalloy of claim 1, wherein, The maximum extrusion force F in the extrusion treatment satisfies the following formula: ； wherein F is the maximum extrusion force, in kN; D is the diameter of the extrusion cylinder, in cm; d is the diameter of the mandrel, in cm; σ is the deformation resistance related to the extrusion rate and temperature, in MPa; λ is the extrusion ratio; and L is the length of the pipe blank, in cm.

3. The method of claim 1, wherein the surface defects are reduced by, Before the step of the hot extrusion treatment, the method further comprises: subjecting the pipe blank to heat preservation treatment.

4. The method of reducing surface defects of hot-extruded, wrought pipe of a wrought superalloy of claim 3, wherein, The temperature of the heat preservation treatment is 1150-1230℃; the time of the heat preservation treatment is ≥ the wall thickness of the pipe blank × 2 min / mm; wherein the time of the heat preservation treatment is in min, and the wall thickness of the pipe blank is in mm.

5. The method of reducing surface defects of hot-extruded, wrought pipe of a wrought superalloy of claim 3, wherein, Glass powder is coated on the surface of the pipe blank after the heat preservation treatment; preferably, the particle size of the glass powder is 80-120 mesh.

6. The method of reducing surface defects of hot-extruded, wrought pipe of a wrought superalloy of claim 1, wherein, The step of preparing the tonnage wrought superalloy ingot into a pipe blank comprises: subjecting the tonnage wrought superalloy ingot to forging treatment, so that the columnar crystal structure in the tonnage wrought superalloy ingot is transformed into equiaxed crystal structure, to obtain an alloy forging blank; then subjecting the alloy forging blank to heat preservation treatment, upsetting treatment and punching treatment in sequence, to obtain the pipe blank.

7. The method of reducing surface defects of hot-extruded, wrought pipe of a wrought superalloy of claim 1, wherein, The tonnage wrought superalloy ingot has non-metallic impurities O content ≤20 ppm, N content ≤35 ppm and H content ≤3 ppm; and / or The tonnage wrought superalloy ingot is a 3-6 tonnage wrought superalloy ingot; and / or The tonnage wrought superalloy ingot is obtained by sequentially subjecting alloy raw materials to vacuum induction melting and vacuum self-consumption remelting.

8. The method of reducing surface defects of hot-extruded, wrought pipe of a wrought superalloy of claim 1, wherein, After the step of the extrusion treatment, an extrusion blank is obtained, and the extrusion blank is subjected to cooling treatment.

9. The method of reducing surface defects of a hot-extruded, wrought pipe of a wrought superalloy of claim 8, wherein, The cooling treatment adopts water cooling; Preferably, the time of the cooling treatment is ≥30 min; and the extrusion blank is taken out until it is cooled to ≤100℃.

10. A wrought, high temperature alloy, hot extruded pipe characterized by, The extruded pipe is obtained by the method for reducing surface defects of wrought superalloy hot extruded pipes according to any one of claims 1-9, and the surface of the extruded pipe is free of orange peel, streamline and fold, the grain boundary carbide is discontinuously distributed, and the size of the carbide is <3 μm.

Images