A processing technology for cobalt-based high-temperature alloy seamless pipe

Abstract

The present invention discloses a processing technology for a cobalt-based high-temperature alloy seamless pipe, which belongs to the technical field of metal pipes and solves the problem that cobalt-based high-temperature alloys in the prior art cannot achieve mass industrial production. The processing technology comprises the following steps: providing a forged bar, mechanically punching a hole in the center along its axis to obtain a punched tube blank; cold working and intermediate annealing the punched tube blank to a target size to obtain a tube blank to be processed; and annealing the tube blank to obtain a seamless pipe. The processing technology can be used for the processing of cobalt-based high-temperature alloy seamless pipes.

Description

Technical Field

[0001] The invention belongs to the technical field of metal pipes, and in particular relates to a processing technology for a cobalt-based high-temperature alloy seamless pipe. Background Art

[0002] As a cobalt-based high-temperature alloy with high carbon, high chromium and high tungsten, HS5188 alloy has excellent resistance to thermal ablation and thermal erosion, oxidation resistance and high strength and toughness. It performs well in harsh environments such as high temperature, high pressure and high overload in the field of aerospace power.

[0003] In the prior art, a small batch of seamless pipes developed and trial-produced can be used to make rocket gas conduits, which have been proven to have excellent performance. However, the alloy processed pipes cannot be mass-produced industrially at present. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide a processing technology for cobalt-based high-temperature alloy seamless pipes, which solves the problem that cobalt-based high-temperature alloys in the prior art cannot be mass-produced in an industrialized manner.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] The present invention provides a processing technology for a cobalt-based high-temperature alloy seamless pipe, comprising the following steps:

[0007] Step 1: Provide a forged bar, perform mechanical punching at the center along its axis, and obtain a punched tube blank;

[0008] Step 2: cold working and intermediate annealing are performed on the punched tube blank to a target size to obtain a tube blank to be processed;

[0009] Step 3: The tube blank to be processed is subjected to finished annealing to obtain a seamless tube.

[0010] Furthermore, the composition of the cobalt-based high-temperature alloy includes, by mass percentage, Cr 20-30, Ni 20-30, W10-20 and Co 40-50, and the room temperature tensile strength R m ≥860MPa, room temperature yield strength R P0.2 ≥380MPa.

[0011] Further, the mechanical punching comprises the following steps:

[0012] Step 11: punching a hole at the center of the forged bar along the axis of the forged bar, the ratio of the inner diameter of the punched hole to the target inner diameter is 5-8:12-16, and a tube blank after punching is obtained;

[0013] Step 12: Perform secondary punching on the tube blank after the primary punching, wherein the ratio of the inner diameter of the secondary punching to the target inner diameter is 10-11:12-16, and the tube blank after the secondary punching is obtained;

[0014] Step 13: Grind the inner hole of the tube blank after secondary punching to obtain the punched tube blank.

[0015] Further, in step 2, the outer diameter of the seamless pipe is greater than or equal to 20 mm, and the cold working is a cold rolling process;

[0016] The outer diameter of the seamless pipe is less than 20mm, and the cold working is cold drawing.

[0017] Further, the cold rolling process comprises the following steps:

[0018] Step 21: cold rolling the punched tube billet to reduce the diameter and wall thickness of the punched tube billet;

[0019] Step 22: Degreasing, intermediate annealing, straightening and polishing are performed on the cold-rolled tube billet in sequence;

[0020] Step 23: Repeat steps 21 to 22 until the target size is reached.

[0021] Further, the cold drawing process comprises the following steps:

[0022] Step 21': lubricate and coat the punched tube;

[0023] Step 22': Heading and cold drawing the coated tube blank so that the coated tube blank has a reduced diameter but not a reduced wall;

[0024] Step 23': performing intermediate annealing on the cold drawn tube blank;

[0025] Step 24': Repeat steps 21' to 23' until the target size is reached.

[0026] Furthermore, the following steps are also included before mechanical punching:

[0027] The forged bars are subjected to a pre-annealing softening treatment.

[0028] Furthermore, before the mechanical punching, the following step is also included: using a lathe to polish the outer surface of the forged bar.

[0029] Furthermore, in step 2, the annealing system of the intermediate annealing is as follows: the furnace temperature is not greater than 800°C, the heating temperature is 1180-1200°C, the holding time is 1-2h, and the cooling rate is 200-250°C / min.

[0030] Furthermore, the annealing system of step 3 is as follows: the heating temperature is 1180-1200° C., the holding time is 0.5-1.0 h, and the cooling rate is 200-250° C. / min.

[0031] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0032] A) In the processing technology of the cobalt-based high-temperature alloy seamless pipe provided by the present invention, a pipe blank is prepared by mechanical drilling and grinding of a forged bar, and then a finished seamless pipe is manufactured by cold processing technology, which solves the preparation problem of the cobalt-based high-temperature alloy seamless pipe better. The processed and manufactured pipe has good quality and excellent performance, and the yield rate is improved, filling the gap of this type of alloy pipe in China and laying a technical foundation for its application in the field of aerospace power.

[0033] B) In the processing technology of the cobalt-based high-temperature alloy seamless pipe provided by the present invention, in view of the special forming characteristics of the cobalt-based high-temperature alloy seamless pipe, in the process of mechanical drilling, the inner hole of the pipe after the first drilling is ground, and the traces left by the drilling of the drill bit on the inner hole surface can be ground clean, ensuring that the inner hole surface is smooth and free of metallurgical defects such as drill bit processing threads, scratches, pits, etc., thereby effectively reducing the occurrence of inner hole defects, dimensional deviations and cracks in the subsequent pipe processing process. Production practice shows that the inner hole polishing process added to the cobalt-based high-temperature alloy pipe can greatly improve the non-destructive testing qualified rate of the finished pipe. In practical applications, the control of the ratio of the inner diameter after drilling to the target inner diameter is one of the key control parameters that can be used for mechanical drilling of cobalt-based high-temperature alloys.

[0034] C) In the processing technology of the cobalt-based high-temperature alloy seamless pipe provided by the present invention, in view of the characteristics of the cobalt-based high-temperature alloy, such as fast deformation hardening rate, large cold deformation resistance and easy cracking due to cold deformation, when formulating the cold rolling process and parameter control, firstly, the number of cold rolling passes is increased (for example, 6 to 8 times), and the deformation amount between each pass is reduced (the maximum deformation amount of cold rolling with a mandrel does not exceed 40%, for example, 10 to 36%); secondly, intermediate annealing and cold rolling are performed alternately, which can ensure the plasticity of the tube blank during the cold rolling process, effectively control the distribution of cold rolling resistance, and thus significantly reduce the tendency of cold rolling cracking.

[0035] D) In ​​the processing technology of the cobalt-based high-temperature alloy seamless pipe provided by the present invention, for the cold drawing processing of the cobalt-based high-temperature alloy pipe, the deformation amount per pass must also be strictly controlled (the maximum deformation amount of cold drawing without a mandrel does not exceed 30%, for example, 10-28%), and the number of cold drawing passes is increased (for example, 3-5 times), avoiding single-pass cold drawing with large deformation, and combining the use of a mandrel-free empty drawing process, which can reduce the scratches and scratches on the inner hole surface caused by irregular sliding of the mandrel during the cold drawing process, and effectively improve the inner hole surface quality of the finished seamless pipe.

[0036] E) In the processing technology of the cobalt-based high-temperature alloy seamless pipe provided by the present invention, due to the special use environment of the cobalt-based high-temperature alloy seamless pipe, the surface quality requirements of the inner and outer walls of the pipe are relatively high. If a conventional annealing furnace is used for intermediate annealing and finished product annealing, the heating temperature of the cobalt-based high-temperature alloy is extremely high (1180°C), which will cause the inner and outer walls of the pipe (the pipe blank after punching or the pipe blank to be processed) to oxidize more significantly, and pickling must be taken to remove the oxide layer later. However, over-acid or unwashed conditions often occur during the pickling process, resulting in a large number of corrosion pits, pits or unwashed oxidized black skin, interlayers, etc. on the surface of the pipe blank, especially the inner hole surface. These defects cannot be removed during the subsequent cold treatment process and are very likely to be converted into crack sources. Therefore, for the cobalt-based high-temperature alloy pipe blank, vacuum or mixed gas protection is used for intermediate annealing and finished product annealing, and the pickling process is abolished, thereby effectively improving the surface quality of the pipe blank. It should be noted that the present invention does not use acid and alkali washing during the entire processing process, which can more effectively ensure the environmental protection of the process and the surface quality of the seamless pipe.

[0037] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0039] Figure 1 The metallographic structure diagram of the seamless tube obtained by the processing technology of the cobalt-based high-temperature alloy seamless tube provided in the first embodiment of the present invention;

[0040] Figure 2 This is a physical picture of the cobalt-based high-temperature alloy seamless pipe processed according to Example 1 of the present invention. DETAILED DESCRIPTION

[0041] Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0042] Cobalt-based high-temperature alloys are difficult-to-deform alloy materials. In order to improve their oxidation resistance, hot corrosion, and sulfidation performance at higher temperatures and improve their high-temperature mechanical properties, a large amount of alloy strengthening elements (such as Cr, W, Mo, Al, Ti, Nb and rare earths) are added. The high alloying composition design will inevitably make the cold and hot processing of alloy seamless pipes extremely difficult.

[0043] The traditional tube processing process is to prepare the tube blank by hot rolling and perforation, which is also one of the biggest differences from the mechanical perforation of the present invention. The characteristics of the traditional hot rolling and perforation process are: high production efficiency, large production capacity, and batch production can be realized. However, due to the relatively severe metal deformation and complex processing deformation stress during the hot rolling and perforation of the bar, although it can meet the production needs of ordinary low-strength steel grades, it is difficult to deform, especially cobalt-based high-temperature alloys. Since the alloy has high high-temperature strength (for example, tensile strength, yield strength, hardness, etc. under high temperature state) and poor deformation plasticity, technical difficulties such as incomplete penetration, cracking and delamination of the inner hole, overburning of the organization, and uneven wall thickness will occur during the hot rolling and perforation process, resulting in an extremely low qualified rate of hot rolling and perforation preparation of tube blanks, deterioration of organization and performance, and failure to obtain tube blanks of qualified quality for subsequent cold rolling and cold drawing.

[0044] The present invention provides a processing technology for a cobalt-based high-temperature alloy seamless pipe, comprising the following steps:

[0045] Step 1: Provide a forged bar, perform mechanical punching, boring and polishing along its axis at the center to obtain a punched tube blank;

[0046] Step 2: cold working and intermediate annealing are performed on the punched tube blank to a target size to obtain a tube blank to be processed;

[0047] Step 3: The tube blank to be processed is subjected to finished annealing to obtain a seamless tube.

[0048] It should be noted that the above processing technology is suitable for the processing of HS5188 cobalt-based high-temperature alloy seamless pipes. Specifically, the composition of HS5188 cobalt-based high-temperature alloy includes: Cr 20-30, Ni 20-30, W 10-20 and Co 40-50 by mass percentage, and the room temperature tensile strength R m ≥860MPa, room temperature yield strength R P0.2 ≥380MPa.

[0049] It should also be noted that the processing technology of the present invention can achieve a production capacity of 500 to 5000 kg / year.

[0050] Compared with the prior art, in the processing technology of the cobalt-based high-temperature alloy seamless tube provided by the present invention, a tube blank is prepared by mechanical drilling and grinding of forged rods, and then the finished seamless tube is manufactured by cold processing technology, which better solves the preparation problem of the cobalt-based high-temperature alloy seamless tube. The processed and manufactured tube has good quality and excellent performance, and the yield rate is improved, which fills the gap of this type of alloy tube in China and lays a technical foundation for its application in the field of aerospace power.

[0051] It should be noted that, by adopting the processing technology of the present invention, not only can qualified blank tubes be smoothly manufactured, but also blank tubes that meet the requirements of subsequent cold processing of finished tubes of different specifications can be processed. In this way, on the basis of the existing domestic production equipment capacity and parameter control accuracy, the manufacturing problem of difficult-to-deform cobalt-based high-temperature alloy tubes is preliminarily solved. Compared with the previous production conditions, the batch production problem of the alloy tubes is met to a certain extent.

[0052] In order to minimize the difficulty of drilling holes with a drill bit in mechanical drilling and improve the efficiency of mechanical drilling, the above-mentioned mechanical drilling also includes the following steps:

[0053] The forged bars are subjected to a pre-annealing softening treatment.

[0054] In this way, the strength and hardness of the forged bar can be effectively and significantly reduced through the pre-annealing softening treatment, and the deformation plasticity of the forged bar can be effectively improved, thereby reducing the difficulty of drilling holes in mechanical drilling and improving the efficiency of mechanical drilling.

[0055] In order to further improve the yield rate of subsequent pipe processing, the following steps are included before the mechanical punching: the outer surface of the forged rod is polished by a lathe to obtain a polished rod.

[0056] In this way, in view of the special forming characteristics of cobalt-based high-temperature alloy seamless pipes, by adding the outer surface polishing process of forged bars, the surface finish of the forged bars can be significantly improved, and the surface can be ensured to be free of metallurgical defects such as scratches, pits, and pits, thereby improving the yield rate of the bars and obtaining smooth bars.

[0057] It should be noted that in actual application, the specific process flow of the above step 1 is as follows: forging bar → pre-annealing and softening treatment → outer surface polishing → mechanical drilling. Through pre-annealing and softening treatment and outer surface polishing, the surface quality is guaranteed to be qualified, and the obtained diameter is 40 to 50 mm (for example, 40 mm, 43 mm, 45 mm, 48 mm or 50 mm), and then mechanical drilling is performed.

[0058] For mechanical punching, specifically, it includes the following steps:

[0059] Step 11: Use a drilling machine to punch a hole in the center of the forged bar along its axis, the ratio of the inner diameter of the punched hole to the target inner diameter is 5-8:12-16, and a punched tube blank is obtained;

[0060] Step 12: Perform secondary punching on the tube blank after the primary punching, wherein the ratio of the inner diameter of the secondary punching to the target inner diameter is 10-11:12-16, and the tube blank after the secondary punching is obtained;

[0061] Step 13: Use a grinder to grind the inner hole of the tube blank after secondary punching to obtain a punched tube blank. The target inner diameter of the punched tube blank is 24 to 32 mm (for example, 24 mm, 28 mm or 32 mm), the outer diameter is 40 to 50 mm (for example, 40 mm, 43 mm, 45 mm, 48 mm or 50 mm), and the wall thickness is 5 to 10 mm (5 mm, 8 mm or 10 mm).

[0062] It should be noted that, in view of the particularity of the forming of cobalt-based high-temperature alloy seamless pipes, during the mechanical drilling process, the inner hole of the pipe is ground after one drilling, which can clean the traces left on the inner hole surface by the drill bit drilling, ensure that the inner hole surface is smooth, and there are no metallurgical defects such as drill bit processing threads, scratches, pitting, etc., thereby effectively reducing the occurrence of inner hole defects, dimensional deviations and cracks in the subsequent pipe processing process, thereby ensuring the uniformity of coaxiality and wall thickness, reducing drilling resistance and drilling difficulty, and avoiding drill bit breakage. Production practice shows that the added inner hole polishing process for cobalt-based high-temperature alloy pipes can greatly improve the non-destructive testing pass rate of finished pipes.

[0063] It should also be noted that, in practical applications, the control of the ratio of the inner diameter after drilling to the target inner diameter is one of the key control parameters that can achieve mechanical drilling of cobalt-based high-temperature alloys.

[0064] For example, in the above step 2, the cold working can be cold rolling or cold drawing, wherein, for seamless pipes with an outer diameter greater than or equal to 20 mm, cold rolling can be used, and for seamless pipes with an outer diameter less than 20 mm, cold drawing can be used.

[0065] Among them, the cold rolling process includes the following steps:

[0066] Step 21: cold rolling the punched tube billet to reduce the diameter and wall thickness of the punched tube billet;

[0067] Step 22: Degreasing, intermediate annealing (temperature is 1100-1200° C., for example, 1100° C., 1150° C., 1170° C., 1190° C. or 1200° C.), straightening and polishing are sequentially performed on the cold-rolled tube blank;

[0068] Step 23: Repeat steps 21 to 22, with 6 to 8 cold rolling passes, until the target size is reached.

[0069] In view of the characteristics of cobalt-based high-temperature alloys, such as fast deformation hardening rate, high cold deformation resistance and easy cracking during cold deformation, when formulating the cold rolling process and parameter control, first, increase the number of cold rolling passes (for example, 6 to 8 times) and reduce the deformation between each pass (the maximum deformation of cold rolling with a mandrel does not exceed 40%, for example, 10 to 36%); secondly, alternate intermediate annealing and cold rolling can ensure the plasticity of the tube during the cold rolling process, effectively control the distribution of cold rolling resistance, and thus significantly reduce the tendency of cold rolling cracking.

[0070] For the cold drawing process, the following steps are included:

[0071] Step 21': lubricate and coat the punched tube;

[0072] Step 22': the coated tube is headed and cold drawn, so that the coated tube is reduced in diameter but not in wall. Specifically, the coated tube is flattened and headed, and the tube is drawn after the cold drawing machine is chucked. The cold drawing can be carried out with a mandrel. In order to reduce the cold drawing stress concentration, the die hole is designed with a small angle (the angle between the die axis and the hole type is 10-20°). The cold drawing process is lubricated with butter lime, and the surface of the tube can also be copper-plated for lubrication if necessary;

[0073] Step 23': performing intermediate annealing on the cold drawn tube blank;

[0074] Step 24': repeat steps 21' to 23', with the number of cold drawing passes being 3 to 5 times, until the target size is reached.

[0075] Similarly, for the cold drawing of cobalt-based high-temperature alloy pipes, it is also necessary to control the deformation amount of each pass (the maximum deformation amount of cold drawing without a mandrel shall not exceed 30%, for example, 10-28%), increase the number of cold drawing passes (for example, 3-5 times), avoid single-pass cold drawing with large deformation, and combine it with the use of a mandrel-free empty drawing process to reduce the scratches and scratches on the inner hole surface caused by irregular sliding of the mandrel during the cold drawing process, effectively improving the inner hole surface quality of the finished seamless pipe.

[0076] Considering that the recrystallization temperature of cobalt-based high-temperature alloys is high and carbide and carbonitride precipitation strengthening is generally used, the solution and annealing temperatures are also higher than other types. In the above step 2, the annealing system of the intermediate annealing is as follows: the furnace temperature is not more than 800°C to prevent thermal stress deformation, bending and cracking, the heating temperature is 1180-1200°C, the holding time is 1-2h, and the furnace is filled with Ar gas quenching and rapidly cooled (cooling rate is 200-250°C / min) to below 700°C.

[0077] Correspondingly, the annealing system of the above step 3 is as follows: heating temperature is 1180-1200°C, holding time is 0.5-1.0h, and rapid cooling is performed by quenching with Ar gas (cooling rate is 200-250°C / min).

[0078] In order to reduce oxidation during the processing, the intermediate annealing in step 2 and the finished product annealing in step 3 above adopt vacuum or gas protection. This is because, due to the special use environment of cobalt-based high-temperature alloy seamless pipes, the surface quality requirements of the inner and outer walls of the pipes are relatively high. If a conventional annealing furnace is used for intermediate annealing and finished product annealing, the heating temperature of the cobalt-based high-temperature alloy is extremely high (1180°C), which will cause the inner and outer walls of the pipe (the tube blank after punching or the tube blank to be processed) to oxidize more significantly, and pickling must be taken to remove the oxide layer later. However, over-acid or unwashed conditions often occur during the pickling process, resulting in a large number of corrosion pits, pitting or unwashed oxidized black skin, interlayers, etc. on the surface of the tube blank, especially the inner hole surface. These defects cannot be removed during the subsequent cold treatment process and are likely to be converted into crack sources. Therefore, for cobalt-based high-temperature alloy tube blanks, vacuum or mixed gas protection is adopted for intermediate annealing and finished product annealing, and the pickling process is abolished, thereby effectively improving the surface quality of the tube blank. It should be noted that, in the entire processing process of the present invention, acid and alkali washing are not used, which can more effectively ensure the environmental protection of the process and the surface quality of the seamless pipe.

[0079] Among them, the mixed gas protection method is adopted, and the composition of the mixed gas calculated by volume percentage includes: H 2 2~5 and Ar 95~98. This is because Ar usually contains water vapor inevitably, which may cause a small amount of oxidation reaction on the surface of the tube during high temperature annealing. 2 It has reducing properties and uses H 2 It can prevent oxidation of the tube billet during annealing, improve the surface quality of the tube billet, and eliminate the need for subsequent acid and alkali washing. In addition, due to the large specific heat capacity of Ar, it can effectively accelerate the cooling rate of the tube billet during the subsequent annealing cooling process, reaching a cooling rate of 200-250°C / min, and has a good inhibitory effect on the precipitation strengthening phase of the internal structure of the tube billet, thereby improving the plasticity of the tube. It should be noted that in the prior art, for gas protection annealing, usually only a single gas (for example, H 2 ).

[0080] It should be noted that Ar and H 2 Both have the function of preventing oxidation during the annealing process of the pipe, but there are some considerations in their use: although H 2Ar gas not only has good antioxidant effect but also has reducing properties, which is beneficial to the surface finish of the pipe. However, its heat capacity is much smaller than that of Ar gas, and it is flammable and explosive, which is not easy to control safely. Although Ar gas is not reducing, it is stable, non-flammable and non-explosive, and has a large heat capacity. It is very suitable for the rapid cooling rate control required in the process of pipe annealing. By consulting the data of the characteristics of the two gases and comparing the mixing ratios for many times, it is confirmed that when H 2 When the ratio of H2O2 gas is 5% or less, there will be no explosion. The ratio of Ar gas can be controlled above 95%. Under this ratio, the operation safety is significantly improved, and no H 2 Gas explosion problem, not only H 2 The reducing property of the gas is also brought into play to a certain extent, and the rapid cooling effect of the Ar gas is also brought into play. In this way, the simple H 2 The annealing cooling rate of pure Ar gas is slow to control, and the surface oxidation color of the finished tube is obvious.

[0081] Embodiment 1

[0082] In this embodiment, the target size of the cobalt-based high-temperature alloy seamless pipe is: diameter Wall thickness: 2.5.

[0083] The specific processing technology of cobalt-based high-temperature alloy seamless pipe includes the following steps:

[0084] Step a: Use the diameter Forged and solution treated bars are first turned and surface polished to obtain a diameter Light stick.

[0085] Step b: Use The drill bit makes a hole along the axis of the bar, and then The drill bit performs secondary drilling, and the inner hole surface is polished on the grinder to ensure that the inner hole of the tube is smooth and free of defects.

[0086] Step c: Use a 10-ton pipe cold drawing unit, and control the outer diameter deformation of the pipe in each pass as follows: Since the cold drawing process reduces the diameter without reducing the wall thickness, the wall thickness remains at 2.5.

[0087] Step d: The finished cold drawn tube is annealed in a gas shielded annealing process. 2 Mixed gas (Ar volume percentage is 95, H 2 The volume percentage is 5) and the annealing and softening treatment is carried out in a protected annealing furnace, the heating temperature is 1180℃, the holding time is 0.5h, and Ar or H is filled during cooling. 2 Rapid cooling by gas quenching (cooling rate is 240℃ / min).

[0088] Table 1 Cold drawing, intermediate annealing and finished product annealing process of Example 1

[0089]

[0090]

[0091] The comprehensive performance test results of the seamless pipes obtained by the above processing technology are as follows:

[0092] Table 2 Room temperature tensile properties of the seamless pipe of Example 1

[0093]

[0094] Table 3 800℃ tensile properties of seamless pipe of Example 1

[0095]

[0096] Table 4 1000℃ tensile properties of seamless pipe of Example 1

[0097]

[0098] The seamless pipe of this embodiment is subjected to metallographic structure test (see Figure 1 ), ultrasonic flaw detection test, non-destructive flaw detection test, product size test, pipe surface quality test and curvature test.

[0099] From the metallographic organization diagram, it can be seen that the seamless pipe is a single-phase austenite structure with fine dispersed carbides and uniform organization; the ultrasonic flaw detection test shows that no excessive defects are found; the non-destructive flaw detection test surface, after eddy current detection, no excessive defects are found in the pipe, and the GB / T7735-2016E2 grade standard requirements are reviewed; the product size test shows that the product size is The surface quality test of the pipe shows that the surface is clean, with no visible flash or burrs, and the out-of-roundness and wall thickness unevenness are within the tolerance; the curvature test shows that the curvature of the pipe is 0.95mm / m, not exceeding 2.0mm / m.

[0100] The actual picture of the cobalt-based high-temperature alloy seamless pipe processed in this embodiment is shown in Figure 2 .

[0101] Embodiment 2

[0102] In this embodiment, the target size of the cobalt-based high-temperature alloy seamless pipe is: diameter Wall thickness: 2.5.

[0103] The specific processing technology of cobalt-based high-temperature alloy seamless pipe includes the following steps:

[0104] Step a: Use the diameter Forged and solution treated bars are first turned and surface polished to obtain a diameter Light stick.

[0105] Step b: Use The drill bit makes a hole along the axis of the bar, and then The drill is used for secondary drilling, and the inner hole surface is polished on the grinder to a diameter of And ensure that the inner hole of the tube is smooth and free of defects.

[0106] Step c: Using LD-60 and LD-30 cold rolling mills, the outer diameter deformation of the pipe is controlled as follows: The wall thickness deformation of the pipe in each pass is controlled as follows: 8.0→7.0→6.0→5.0→4.0→3.5→3.0→2.5.

[0107] Step d: The finished cold-rolled tube is annealed in a gas shielded annealing process. 2 Mixed gas (Ar volume percentage is 98, H 2 The volume percentage is 2) annealing and softening treatment is carried out in a protective annealing furnace, heating temperature: 1180±10℃, holding time: 0.5h, and Ar or H is filled during cooling. 2 Gas quenching for rapid cooling.

[0108] Table 5 Cold rolling, intermediate annealing and finished product annealing process of Example 2

[0109]

[0110]

[0111] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A processing technology for a cobalt-based high-temperature alloy seamless pipe, characterized in that: The steps include: Step 1: Provide a forged bar, perform mechanical punching at the center along its axis, and obtain a punched tube blank; Step 2: cold working and intermediate annealing are performed on the punched tube blank to a target size to obtain a tube blank to be processed; Step 3: annealing the tube blank to obtain a seamless tube; The composition of the cobalt-based high-temperature alloy includes, by mass percentage, 20-30% Cr, 20-30% Ni, 10-20% W and 40-50% Co. The room temperature tensile strength R m ≥860MPa, room temperature yield strength R P0.2 ≥380MPa; The mechanical punching comprises the following steps: Step 11: punching a hole at the center of the forged bar along the axis of the forged bar, the ratio of the inner diameter of the punching hole to the target inner diameter is 5-8:12-16, and a punched tube blank is obtained, and the inner hole of the punched tube blank is ground; Step 12: Perform secondary punching on the tube blank after the primary punching, wherein the ratio of the inner diameter of the secondary punching to the target inner diameter is 10-11:12-16, and the tube blank after the secondary punching is obtained; Step 13: Grinding the inner hole of the tube blank after the secondary punching to obtain the punched tube blank; In step 2, the outer diameter of the seamless pipe is greater than or equal to 20 mm, and the cold working is a cold rolling process; the cold rolling process includes the following steps: Step 21: cold rolling the punched tube billet to reduce the diameter and wall of the punched tube billet, the number of cold rolling passes is 6 to 8 times, and the maximum deformation of the cold rolling with a mandrel is 10 to 36%; Step 22: Degreasing, intermediate annealing, straightening and polishing are performed on the cold-rolled tube billet in sequence; Step 23: Repeat steps 21 to 22 until the target size is reached; In step 2, the annealing system of the intermediate annealing is as follows: the furnace temperature is not greater than 800°C, the heating temperature is 1180-1200°C, the holding time is 1-2h, and the cooling rate is 200-250°C / min; The annealing system of step 3 is as follows: heating temperature is 1180-1200°C, holding time is 0.5-1.0h, cooling rate is 200-250°C / min; The intermediate annealing in step 2 and the finished product annealing in step 3 are performed in a mixed gas protection manner, and the composition of the mixed gas includes, by volume percentage, 2 to 5% H2 and 95 to 98% Ar.

2. The processing technology of the cobalt-based high-temperature alloy seamless pipe according to claim 1 is characterized in that: The method also includes the following steps before the mechanical punching: polishing the outer surface of the forged bar by using a lathe.

Images