CN115138706A - Processing technology of cobalt-based high-temperature alloy seamless pipe - Google Patents
Processing technology of cobalt-based high-temperature alloy seamless pipe Download PDFInfo
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- CN115138706A CN115138706A CN202210563815.5A CN202210563815A CN115138706A CN 115138706 A CN115138706 A CN 115138706A CN 202210563815 A CN202210563815 A CN 202210563815A CN 115138706 A CN115138706 A CN 115138706A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
- B21C37/06—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of tubes or metal hoses; Combined procedures for making tubes, e.g. for making multi-wall tubes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C1/00—Manufacture of metal sheets, metal wire, metal rods, metal tubes by drawing
- B21C1/16—Metal drawing by machines or apparatus in which the drawing action is effected by other means than drums, e.g. by a longitudinally-moved carriage pulling or pushing the work or stock for making metal sheets, bars, or tubes
- B21C1/22—Metal drawing by machines or apparatus in which the drawing action is effected by other means than drums, e.g. by a longitudinally-moved carriage pulling or pushing the work or stock for making metal sheets, bars, or tubes specially adapted for making tubular articles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
- B21C37/06—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of tubes or metal hoses; Combined procedures for making tubes, e.g. for making multi-wall tubes
- B21C37/30—Finishing tubes, e.g. sizing, burnishing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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Abstract
The invention discloses a processing technology of a cobalt-based high-temperature alloy seamless pipe, belongs to the technical field of metal pipes, and solves the problem that the cobalt-based high-temperature alloy in the prior art cannot realize batch industrial production. The processing technology comprises the following steps: providing a forged bar, and mechanically punching at the center along the axis of the forged bar to obtain a punched tube blank; performing cold machining and intermediate annealing on the punched pipe blank to a target size to obtain a pipe blank to be treated; and annealing the finished product of the tube blank to be treated to obtain the seamless tube. The processing technology can be used for processing cobalt-based high-temperature alloy seamless pipes.
Description
Technical Field
The invention belongs to the technical field of metal pipes, and particularly relates to a processing technology of a cobalt-based high-temperature alloy seamless pipe.
Background
The HS5188 alloy is a cobalt-based high-temperature alloy with high carbon, high chromium and high tungsten, has excellent heat ablation resistance, heat scouring resistance, oxidation resistance and high toughness, and has good service performance in severe environments such as high temperature, high pressure, large overload and the like in the aerospace power field.
In the prior art, small-batch seamless pipes developed and trial-produced can be used for manufacturing rocket gas conduits, and the service performance is proved to be excellent. However, the alloy processing pipe cannot realize batch industrial production at present.
Disclosure of Invention
In view of the above analysis, the invention aims to provide a processing technology of a cobalt-based high-temperature alloy seamless pipe, which solves the problem that the cobalt-based high-temperature alloy in the prior art cannot realize batch industrial production.
The purpose of the invention is mainly realized by the following technical scheme:
the invention provides a processing technology of a cobalt-based high-temperature alloy seamless pipe, which comprises the following steps:
step 1: providing a forged bar, and mechanically punching at the center along the axis of the forged bar to obtain a punched tube blank;
and 2, step: performing cold machining and intermediate annealing on the punched pipe blank to a target size to obtain a pipe blank to be treated;
and step 3: and annealing the finished product of the tube blank to be treated to obtain the seamless tube.
Further, the cobalt-based high-temperature alloy comprises the following components in percentage by mass: cr 20-30, ni 20-30, W10-20 and Co 40-50, room temperature tensile strength R m Greater than or equal to 860MPa and room temperature yield strength R P0.2 ≥380MPa。
Further, the mechanical punching comprises the following steps:
step 11: and (3) punching at the center of the forged bar material along the axis of the forged bar material once, wherein the ratio of the inner diameter of the punched hole to the target inner diameter is 5-8: 12-16, obtaining a tube blank after primary punching;
step 12: and (3) carrying out 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 obtaining a tube blank after secondary punching;
step 13: and grinding the inner hole of the tube blank after secondary punching to obtain the punched tube blank.
Further, in the step 2, the outer diameter of the seamless pipe is greater than or equal to 20mm, and cold machining is cold rolling treatment;
the outer diameter of the seamless pipe is less than 20mm, and cold processing is cold drawing processing.
Further, the cold rolling process comprises the following steps:
step 21: cold rolling the punched pipe blank to reduce the diameter and the wall of the punched pipe blank;
step 22: sequentially carrying out oil removal, intermediate annealing, straightening and polishing on the cold-rolled tube blank;
step 23: and repeating the steps 21 to 22 until the target size is achieved.
Further, the cold drawing process comprises the following steps:
step 21': lubricating and coating the punched tube blank;
step 22': heading and cold-drawing the coated tube blank to reduce the diameter of the coated tube blank without reducing the wall;
step 23': performing intermediate annealing on the cold-drawn tube blank;
step 24': and repeating the steps 21 'to 23' until the target size is achieved.
Further, the mechanical punching method also comprises the following steps of:
and (4) performing pre-annealing softening treatment on the forged bar.
Further, the mechanical punching method also comprises the following steps before mechanical punching: and (4) polishing the outer surface of the forged bar by adopting a lathe.
Further, in step 2, the annealing schedule of the intermediate annealing is as follows: the charging temperature is not more than 800 ℃, the heating temperature is 1180-1200 ℃, the heat preservation time is 1-2 h, and the cooling speed is 200-250 ℃/min.
Further, the annealing regime of step 3 is as follows: the heating temperature is 1180-1200 ℃, the heat preservation time is 0.5-1.0 h, and the cooling speed is 200-250 ℃/min.
Compared with the prior art, the invention can realize at least one of the following beneficial effects:
a) In the processing technology of the cobalt-based high-temperature alloy seamless pipe, the forged bar is mechanically drilled and polished to prepare the pipe blank, and then the finished product seamless pipe is manufactured by adopting a cold processing technology, so that the problem of preparing the cobalt-based high-temperature alloy seamless pipe is better solved, the processed and manufactured pipe has good quality and excellent performance, the yield is improved, the blank of the type of alloy pipe in China is filled, and the technical foundation is laid for the application of the alloy pipe in the field of aerospace power.
B) In the processing technology of the cobalt-based high-temperature alloy seamless pipe, aiming at the forming particularity of the cobalt-based high-temperature alloy seamless pipe, an inner hole is ground on the pipe subjected to primary punching in the mechanical drilling process, so that the trace remained on the surface of the inner hole due to the punching of a drill bit can be completely ground, the surface of the inner hole is ensured to be smooth, and the metallurgical defects such as machining threads, scratches, pits and the like of the drill bit are avoided, so that the defects, the size deviation and the cracking of the inner hole in the subsequent pipe processing process are effectively reduced. In practical application, the control of the ratio of the inner diameter after punching to the target inner diameter is one of the key control parameters of the cobalt-based high-temperature alloy by adopting mechanical punching.
C) In the processing technology of the cobalt-based high-temperature alloy seamless pipe, aiming at the characteristics of high deformation hardening rate, large cold deformation resistance and easy cracking of the cobalt-based high-temperature alloy, when a cold rolling technology and parameter control are set, firstly, the number of cold rolling passes is increased (for example, 6-8 times), and the deformation amount between every two passes is reduced (the maximum deformation amount of cold rolling with a mandrel does not exceed 40 percent, for example, 10-36 percent); and secondly, intermediate annealing and cold rolling are alternately carried out, so that the plasticity of the tube blank in the cold rolling process can be ensured, and the cold rolling resistance distribution is effectively controlled, thereby obviously reducing the cold rolling cracking tendency.
D) In the processing technology of the cobalt-based high-temperature alloy seamless pipe, the cold drawing processing of the cobalt-based high-temperature alloy seamless pipe is also required to strictly control the pass deformation (the maximum cold drawing deformation of the coreless rod is not more than 30 percent, such as 10 to 28 percent), increase the number of cold drawing passes (such as 3 to 5 times), avoid single-pass large-deformation cold drawing, and reduce scratches and scratches caused by irregular sliding of the core rod in the cold drawing process by combining the coreless rod idle drawing technology, thereby effectively improving the surface quality of the inner hole of the finished seamless pipe.
E) In the processing technology of the cobalt-based high-temperature alloy seamless pipe, the cobalt-based high-temperature alloy seamless pipe is special in use environment, so that the requirement on the surface quality of the inner wall and the outer wall of the pipe is high. If a conventional annealing furnace is adopted for intermediate annealing and finished product annealing, the cobalt-based high-temperature alloy has extremely high heating temperature (1180 ℃) and can cause the oxidation of the inner wall and the outer wall of a pipe (a punched pipe blank or a pipe blank to be treated) to be more remarkable, and an acid cleaning process is required to remove an oxidation layer subsequently, however, the situation of peracid or no cleaning often occurs in the acid cleaning process, so that a large number of corrosion pits, pockmarks or oxidation black skin and interlayers which are not cleaned exist on the surface of the pipe blank, particularly the surface of an inner hole, and the defects can not be removed in the subsequent cold treatment process and are possibly converted into crack sources. Therefore, aiming at the cobalt-based high-temperature alloy tube blank, the intermediate annealing and the finished product annealing adopt a vacuum or mixed gas protection mode, and the pickling process is eliminated, so that the surface quality of the tube blank is effectively improved. It should be noted that in the whole processing process, acid and alkali washing is not adopted, so that the environmental protection property of the process and the surface quality of the seamless pipe can be more effectively ensured.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
FIG. 1 is a metallographic structure diagram of a seamless pipe obtained by the processing technology of a cobalt-based superalloy seamless pipe provided in the first embodiment of the present invention;
FIG. 2 is a schematic representation of a cobalt-based superalloy seamless pipe processed according to an embodiment of the present invention.
Detailed Description
The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention.
The cobalt-based high-temperature alloy belongs to an alloy material difficult to deform, a large amount of alloy strengthening elements (such as Cr, W, mo, al, ti, nb, rare earth and the like) are added to improve the oxidation resistance, hot corrosion resistance and vulcanization performance at higher temperature and improve the high-temperature mechanical property, and the design of high-alloying components inevitably leads to that the cold and hot processing of an alloy seamless pipe becomes extremely difficult.
The traditional tube processing technology is to adopt a hot rolling perforation method to prepare a tube blank, which is one of the biggest differences from the mechanical perforation method of the invention. The traditional hot rolling perforation process has the characteristics that: the production efficiency is high, the capacity is high, the mass production can be realized, but, in the bar hot rolling and punching process, the metal deformation is severe, the processing deformation stress is complex, and the production requirement of common low-strength steel can be met, but for the alloy which is difficult to deform, particularly cobalt-based high-temperature alloy, the alloy has high-temperature strength (such as tensile strength, yield strength, hardness and the like in a high-temperature state) and poor deformation plasticity, so the technical problems of impassability in penetration, inner hole cracking and layering, tissue overburning, uneven wall thickness and the like can occur in the hot rolling and punching process, the qualification rate of preparing the tube blank by hot rolling and punching is extremely low, the tissue and the performance are deteriorated, and the qualified tube blank for the subsequent cold rolling and cold drawing processing cannot be obtained.
The invention provides a processing technology of a cobalt-based high-temperature alloy seamless pipe, which comprises the following steps:
step 1: providing a forged bar, and mechanically punching, boring and polishing the center of the forged bar along the axis of the forged bar to obtain a punched tube blank;
step 2: performing cold machining and intermediate annealing on the punched pipe blank to a target size to obtain a pipe blank to be treated;
and step 3: and annealing the finished product of the tube blank to be treated to obtain the seamless tube.
The processing technology is suitable for processing HS5188 cobalt-based high-temperature alloy seamless pipes, and specifically, the HS5188 cobalt-based high-temperature alloy comprises the following components in percentage by mass: cr 20-30, ni 20-30, W10-20 and Co 40-50, tensile strength R at room temperature m Greater than or equal to 860MPa and room temperature yield strength R P0.2 ≥380MPa。
It should also be noted that the processing technology of the invention can achieve a production capacity of 500-5000 kg/year.
Compared with the prior art, in the processing technology of the cobalt-based high-temperature alloy seamless pipe, the forged bar is mechanically drilled and ground to prepare the pipe blank, and then the finished product seamless pipe is manufactured by adopting a cold processing technology, so that the preparation of the cobalt-based high-temperature alloy seamless pipe is better solved, the processed and manufactured pipe is good in quality and excellent in performance, the yield is improved, the blank of the alloy pipe of the type in China is filled, and the technical basis is laid for the application of the alloy pipe in the aerospace power field.
It should be noted that, by adopting the processing technology of the invention, not only can the blank pipe with qualified quality be smoothly manufactured, but also the blank pipe for cold processing of subsequent finished pipes with different specifications can be processed, thus the manufacturing problem of the cobalt-based high-temperature alloy pipe which is difficult to deform is primarily solved on the basis of the capacity of the domestic existing production equipment and the parameter control precision, and the batch production problem of the alloy pipe is satisfied to a certain extent compared with the prior production condition.
In order to reduce the difficulty of drilling by a drill bit in mechanical drilling to the greatest extent and improve the efficiency of mechanical drilling, the mechanical drilling method further comprises the following steps of:
and (4) performing pre-annealing softening treatment on the forged bar.
Like this, through annealing softening treatment in advance can effectively show intensity and the hardness that reduces the forging rod to, can effectively improve the deformation plasticity of forging rod, thereby can reduce the degree of difficulty that the drill bit punched in the mechanical punching, improve the efficiency that the machinery punched.
In order to further improve the yield of subsequent pipe processing, the mechanical punching method also comprises the following steps before the mechanical punching: and (5) polishing the outer surface of the forged bar by adopting a lathe to obtain a polished bar.
Therefore, aiming at the forming particularity of the cobalt-based high-temperature alloy seamless pipe, the surface finish of the forged bar can be obviously improved by adding the outer surface polishing process of the forged bar, and metallurgical defects such as scratches, pits, pockmarks and the like on the surface are avoided, so that the yield of the bar can be improved, and the polished bar is obtained.
It should be noted that, in practical applications, the specific process flow of step 1 is as follows: forged bar → pre-annealing softening treatment → outer surface polishing → mechanical perforation. The surface quality is ensured to be qualified by pre-annealing softening treatment and outer surface polishing, the diameter is 40-50 mm (for example, 40mm, 43mm, 45mm, 48mm or 50 mm), and then mechanical punching is carried out.
For mechanical perforation, in particular, it comprises the following steps:
step 11: adopting a drilling machine to perform primary drilling at the center of the forged bar along the axis of the forged bar, wherein the ratio of the inner diameter of the primary drilling to the target inner diameter is 5-8: 12-16, obtaining a tube blank after primary punching;
step 12: and (3) performing secondary punching on the tube blank subjected to the primary punching, wherein the ratio of the inner diameter of the secondary punching to the target inner diameter is 10-11: 12-16, obtaining a tube blank after secondary punching;
step 13: and grinding the inner hole of the secondarily punched tube blank by using a grinding machine to obtain a punched tube blank, wherein the target inner diameter of the punched tube blank is 24-32 mm (for example, 24mm, 28mm or 32 mm), the target outer diameter of the punched tube blank is 40-50 mm (for example, 40mm, 43mm, 45mm, 48mm or 50 mm), and the wall thickness of the punched tube blank is 5-10 mm (5 mm, 8mm or 10 mm).
It should be noted that, aiming at the forming particularity of the cobalt-based high-temperature alloy seamless pipe, in the mechanical drilling process, the inner hole of the pipe after one-time punching is ground, the trace remained on the surface of the inner hole after the punching by a drill bit can be completely ground, the surface of the inner hole is smooth, the metallurgical defects such as thread, scratch, pitting and the like are avoided in the drill bit processing process, the generation of inner hole defects, size deviation and cracking in the subsequent pipe processing process is effectively reduced, the uniformity of coaxiality and wall thickness can be ensured, the punching resistance and the punching difficulty are reduced, and the situation that the drill bit is broken is avoided.
In practical application, the ratio of the inner diameter after the hole drilling to the target inner diameter is one of the key control parameters for realizing the mechanical hole drilling of the cobalt-based high-temperature alloy.
In step 2, the cold working may be cold rolling or cold drawing, wherein the cold rolling may be performed when the outer diameter of the seamless pipe is greater than or equal to 20mm, and the cold drawing may be performed when the outer diameter of the seamless pipe is less than 20 mm.
Wherein, for the cold rolling treatment, the method comprises the following steps:
step 21: cold rolling the punched pipe blank to reduce the diameter and the wall of the punched pipe blank;
step 22: the tube blank after cold rolling is sequentially subjected to oil removal, intermediate annealing (at the temperature of 1100-1200 ℃, for example, 1100 ℃, 1150 ℃, 1170 ℃, 1190 ℃ or 1200 ℃), straightening and polishing;
step 23: and (5) repeating the steps 21 to 22, wherein the cold rolling pass is 6 to 8 times until the steel plate is processed to the target size.
Aiming at the characteristics of high deformation hardening rate, large cold deformation resistance and easy cracking of the cobalt-based high-temperature alloy, when a cold rolling process and parameter control are set, firstly, the number of cold rolling passes is increased (for example, 6-8 times), and the deformation amount between each pass is reduced (the maximum deformation amount of cold rolling with a core rod is not more than 40 percent, for example, 10-36 percent); and secondly, intermediate annealing and cold rolling are alternately carried out, so that the plasticity of the tube blank in the cold rolling process can be ensured, and the cold rolling resistance distribution is effectively controlled, thereby obviously reducing the cold rolling cracking tendency.
For cold drawing, the method comprises the following steps:
step 21': lubricating and coating the punched tube blank;
step 22': heading and cold-drawing the coated tube blank to reduce the diameter of the coated tube blank without reducing the wall of the coated tube blank, specifically, flattening and heading the coated tube blank, drawing the coated tube blank after a clamping head of a tube blank cold-drawing machine, and carrying out cold-drawing with a mandrel, wherein in order to reduce the stress concentration of the cold-drawing, a die hole is designed at a small angle (the included angle between the axis of the die and a hole pattern is 10-20 degrees), the cold-drawing process is lubricated by adopting butter lime, and the surface of the tube can be lubricated by plating copper if necessary;
step 23': performing intermediate annealing on the cold-drawn tube blank;
step 24': and (5) repeating the steps 21 'to 23', wherein the cold drawing pass is 3-5 times until the target size is obtained.
Similarly, for cold drawing of the cobalt-based high-temperature alloy pipe, the pass deformation also needs to be controlled (the maximum deformation of cold drawing of the coreless rod does not exceed 30%, for example, 10-28%), the number of cold drawing passes is increased (for example, 3-5 times), single-pass large-deformation cold drawing is avoided, and the coreless rod blank drawing process is adopted, so that scratches and scratches caused by irregular sliding of the mandrel in the cold drawing process of the inner hole surface can be reduced, and the quality of the inner hole surface of a finished seamless pipe is effectively improved.
Considering that the cobalt-based superalloy has a high recrystallization temperature and is generally precipitation-strengthened by carbides and carbonitrides, and thus has a higher solution and annealing temperature than other types, the annealing schedule of the intermediate annealing in the step 2 is as follows: the temperature of the furnace is not more than 800 ℃ to prevent thermal stress deformation, bending and cracking, the heating temperature is 1180-1200 ℃, the heat preservation time is 1-2 h, and the furnace is taken out and is filled with Ar gas to be quenched and rapidly cooled (the cooling speed is 200-250 ℃/min) to be below 700 ℃.
Accordingly, the annealing schedule of step 3 above is as follows: heating at 1180-1200 deg.c for 0.5-1.0 hr, and quenching with Ar gas at 200-250 deg.c/min for fast cooling.
In order to reduce oxidation in the processing process, the intermediate annealing of the step 2 and the finished product annealing of the step 3 adopt a vacuum or gas protection mode. This is because the cobalt-based superalloy seamless pipe has a high demand for the surface quality of the inner and outer walls of the pipe due to its special use environment. If a conventional annealing furnace is adopted for intermediate annealing and finished product annealing, the cobalt-based high-temperature alloy has extremely high heating temperature (1180 ℃) and can cause the oxidation of the inner wall and the outer wall of a pipe (a punched pipe blank or a pipe blank to be treated) to be more remarkable, and an acid cleaning process is required to remove an oxidation layer subsequently, however, the situation of peracid or no cleaning often occurs in the acid cleaning process, so that a large number of corrosion pits, pockmarks or oxidation black skin and interlayers which are not cleaned exist on the surface of the pipe blank, particularly the surface of an inner hole, and the defects can not be removed in the subsequent cold treatment process and are possibly converted into crack sources. Therefore, aiming at the cobalt-based high-temperature alloy tube blank, the intermediate annealing and the finished product annealing adopt a vacuum or mixed gas protection mode, and the pickling process is eliminated, so that the surface quality of the tube blank is effectively improved. It should be noted that in the whole processing process, acid and alkali washing is not adopted, so that the environmental protection property of the process and the surface quality of the seamless pipe can be more effectively ensured.
Wherein, adopt the mixed gas protection mode, the composition of mixed gas includes according to the volume percent: h 2 2 to 5 and 95 to 98, because Ar usually contains unavoidable moisture, and a small amount of oxidation reaction and H may occur on the surface of the tube blank during the high-temperature annealing process 2 Having reducibility, using H 2 The method can prevent the tube blank from being oxidized in the annealing process, improve the surface quality of the tube blank and avoid subsequent acid and alkali cleaning. In addition, because the specific heat capacity of Ar is larger, the cooling speed of the tube blank can be effectively accelerated in the subsequent annealing and cooling process, the cooling speed is 200-250 ℃/min, and the precipitation strengthening phase of the internal structure of the tube blank is well inhibited, so that the plasticity of the tube can be improved. It should be noted that, in the prior art, only a single gas (e.g., H) is typically used for the gas-shielded anneal 2 )。
In addition, ar and H 2 Both have the effect of preventing oxidation during the annealing treatment of the pipe, but the use of both is considered: although H 2 The gas has good oxidation resistance and reducibility, and has certain benefit on the surface smoothness of the pipe, but the gas has much smaller heat capacity than Ar gas, and is inflammable, explosive and inconvenient for safety control. Although Ar gas has no reducibility, the Ar gas has stable properties, is non-combustible and non-explosive, has large heat capacity, and is very suitable for the cooling speed control of the rapid refrigeration required in the annealing process of the pipe. Through inquiring the data of the characteristics of the two gases and a plurality of times of mixing ratio comparison tests, the product H is proved 2 The gas proportion is not exploded when 5% and below, and the Ar gas proportion can be correspondingly controlled to be more than 95%. Under the condition of the mixture ratio, the operation safety is obviously improved, and no H appears 2 Problem of gas explosion, not only H 2 The reducibility of the gas is also exerted to a certain extent, and the rapid cooling effect of the Ar gas is also exerted to a sufficient extent. Thus, the simple H is improved to a certain extent 2 The annealing cooling speed of the gas is controlled slowly, and the surface oxidation color of the finished pipe product with pure Ar gas is obvious.
Example one
In this example, the target size of the cobalt-based superalloy seamless tube is: diameter of
The wall thickness was 2.5.
The specific processing technology of the cobalt-based high-temperature alloy seamless pipe comprises the following steps:
step a: by diameter
Forging and solution treating bar, turning outer circle and polishing surface to obtain diameter
The light bar of (1).
Step b: by using
The drill bit punches the bar material once along the axis of the bar material and then adopts
And (3) secondary punching is carried out by the drill, the surface of the inner hole is polished by the upper grinding machine, and the inner hole of the tube blank is ensured to be smooth and free of defects.
Step c: adopting a 10-ton pipe cold-drawing unit, and controlling the deformation of the outer diameter of a pass pipe as follows:
the wall thickness is kept at 2.5 because the wall thickness is not reduced by reducing diameter by cold drawing.
Step d: and the cold-drawn pipe finished product is annealed under the protection of gas. Cold drawing of tubes in Ar and H 2 Mixed gas (volume percent of Ar 95,h) 2 The volume percentage of 5) is carried out annealing softening treatment in an annealing furnace protected by the following temperature: 1180 ℃, heat preservation time: 0.5H, filling Ar or H when cooling 2 The gas quenching is carried out for rapid cooling (the cooling speed is 240 ℃/min).
Table 1 cold-drawing, intermediate annealing and final annealing processes of example one
The conditions for carrying out comprehensive performance test on the seamless pipe obtained by the processing technology are as follows:
TABLE 2 room temperature tensile Properties of seamless tubing as in example one
TABLE 3 tensile Properties at 800 ℃ of the seamless pipes of example one
TABLE 4 tensile properties at 1000 ℃ for seamless tubes as in example one
The seamless pipe of the present example was subjected to metallographic structure test (see fig. 1), ultrasonic flaw detection test, nondestructive flaw detection test, product size test, pipe surface quality test, and bending test.
As can be seen from a metallographic structure diagram, the seamless pipe is a single-phase austenite structure, has fine and dispersed carbides, and is uniform in structure; ultrasonic flaw detection tests show that no standard exceeding defect is found; performing nondestructive inspection on the surface, detecting by eddy current, rechecking GB/T7735-2016E2 standard requirements if no standard exceeding defects are found in the pipe; the product size test shows that the product size is
The surface quality test of the pipe shows that the surface is clean, no visible flash and burr exist, and both the out-of-roundness and the wall thickness unevenness do not have super-difference; the bending test shows that the bending of the pipe is 0.95mm/m and not more than 2.0mm/m.
A physical representation of the cobalt-based superalloy seamless pipe processed in this example is shown in FIG. 2.
Example two
In this example, the target size of the cobalt-based superalloy seamless pipe is as follows: diameter of
The wall thickness was 2.5.
The specific processing technology of the cobalt-based superalloy seamless pipe comprises the following steps:
step a: by diameter
Forging and solution treating bar, turning outer circle and polishing surface to obtain diameter
The light bar of (1).
Step b: by using
The drill bit punches the bar material once along the axis of the bar material and then adopts
Drilling with the drill bit for the second time, polishing the surface of the inner hole with the upper grinder to the diameter
And ensure the inner hole of the tube blank to be smooth and free of defects.
Step c: by adopting LD-60 and LD-30 cold rolling units, the external diameter deformation of the pass pipe is controlled as follows:
the control of the wall thickness deformation of the pass tube is as follows: 8.0 → 7.0 → 6.0 → 5.0 → 4.0 → 3.5 → 3.0 → 2.5.
Step d: and (3) annealing the cold-rolled pipe finished product under the protection of gas. Cold drawing of tubes in Ar and H 2 Mixed gas (volume percentage of Ar is 98,H 2 2) annealing and softening treatment in an annealing furnace protected by the following temperature: 1180 + -10 ℃, heat preservation time: 0.5H, filling Ar or H when cooling 2 And (3) performing gas quenching and quick refrigeration.
Table 5 annealing process for cold rolling, intermediate annealing and final product of example two
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (10)
1. The processing technology of the cobalt-based high-temperature alloy seamless pipe is characterized by comprising the following steps of:
step 1: providing a forged bar, and mechanically punching at the center along the axis of the forged bar to obtain a punched tube blank;
step (ii) of 2: performing cold machining and intermediate annealing on the punched pipe blank to a target size to obtain a pipe blank to be processed;
and step 3: and annealing the finished product of the tube blank to be treated to obtain the seamless tube.
2. The processing technology of the cobalt-based superalloy seamless pipe as claimed in claim 1, wherein the cobalt-based superalloy comprises the following components in percentage by mass: cr 20-30, ni 20-30, W10-20 and Co 40-50, tensile strength R at room temperature m Greater than or equal to 860MPa and room-temperature yield strength R P0.2 ≥380MPa。
3. The process for machining the cobalt-based superalloy seamless pipe according to claim 1, wherein the mechanical drilling comprises the following steps:
step 11: punching at the center of the forging bar material along the axis of the forging bar material, wherein the ratio of the inner diameter of the punched hole to the target inner diameter is 5-8: 12-16, obtaining a tube blank after primary punching;
step 12: and (3) performing secondary punching on the tube blank subjected to 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 obtaining a tube blank after secondary punching;
step 13: and grinding the inner hole of the tube blank after secondary punching to obtain the punched tube blank.
4. The processing technology of the cobalt-based superalloy seamless pipe according to claim 1, wherein in the step 2, the outer diameter of the seamless pipe is greater than or equal to 20mm, and the cold working is cold rolling;
the outer diameter of the seamless pipe is less than 20mm, and cold working is cold drawing treatment.
5. The processing technology of the cobalt-based superalloy seamless pipe according to claim 4, wherein the cold rolling treatment comprises the following steps:
step 21: cold rolling the punched tube blank to reduce the diameter and the wall of the punched tube blank;
step 22: sequentially carrying out oil removal, intermediate annealing, straightening and polishing on the cold-rolled tube blank;
step 23: and repeating the steps 21 to 22 until the target size is achieved.
6. The processing technology of the cobalt-based superalloy seamless pipe according to claim 4, wherein the cold-drawing treatment comprises the following steps:
step 21': lubricating and coating the punched tube blank;
step 22': heading and cold-drawing the coated tube blank to reduce the diameter of the coated tube blank without reducing the wall;
step 23': performing intermediate annealing on the cold-drawn tube blank;
step 24': and repeating the steps 21 'to 23' until the target size is achieved.
7. The processing technology of the cobalt-based superalloy seamless pipe according to claim 1, wherein the mechanical drilling is preceded by the following steps:
and (3) performing pre-annealing softening treatment on the forged bar.
8. The process for machining a cobalt-based superalloy seamless pipe according to claim 1, wherein the mechanical drilling is preceded by the steps of: and (4) polishing the outer surface of the forged bar by adopting a lathe.
9. The cobalt-based superalloy seamless pipe machining process according to claims 1 to 8, wherein in the step 2, an annealing schedule of intermediate annealing is as follows: the charging temperature is not more than 800 ℃, the heating temperature is 1180-1200 ℃, the heat preservation time is 1-2 h, and the cooling speed is 200-250 ℃/min.
10. The processing technology of the cobalt-based superalloy seamless pipe according to claims 1 to 8, wherein the annealing schedule of the step 3 is as follows: the heating temperature is 1180-1200 ℃, the heat preservation time is 0.5-1.0 h, and the cooling speed is 200-250 ℃/min.
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