CN113458176B - Manufacturing method of high-precision seamless tube with outer hexagonal and inner circular special-shaped cross section for nuclear power - Google Patents
Manufacturing method of high-precision seamless tube with outer hexagonal and inner circular special-shaped cross section for nuclear power Download PDFInfo
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- CN113458176B CN113458176B CN202110735012.9A CN202110735012A CN113458176B CN 113458176 B CN113458176 B CN 113458176B CN 202110735012 A CN202110735012 A CN 202110735012A CN 113458176 B CN113458176 B CN 113458176B
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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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- 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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- 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
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
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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
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
- C21D1/773—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material under reduced pressure or vacuum
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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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
- C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys
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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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Abstract
The invention discloses a high-precision outer hexagonal inner circular special-shaped section seamless pipe for nuclear power, which is characterized in that the pipe is made of stainless steel or corrosion-resistant alloy with the elongation rate of more than 35%; the outer distance between the two sides is 10 mm-68 mm, and the deviation of the outer distance between the two sides is +/-0.05 mm; the diameter of the inner circle is 9 mm-66 mm, and the deviation of the diameter of the inner circle is +/-0.05 mm. The invention also discloses a preparation method of the high-precision seamless pipe with the outer hexagon and the inner circle and the special-shaped section for nuclear power.
Description
Technical Field
The invention relates to a high-precision seamless pipe with an outer hexagonal and inner circular special-shaped section for nuclear power and a manufacturing method thereof, belonging to the technical field of preparation of special alloy seamless pipes in new materials.
Background
The traditional manufacturing process of the outer hexagonal inner circular seamless pipe adopts multi-pass cold rolling and multi-pass cold drawing forming or adopts a hot processing process to shape and multi-pass cold drawing to determine the size, and the process proposal has multiple process passes, low production efficiency and low dimensional precision of the produced product, and can not meet the production requirements of high-precision outer hexagonal and inner circular pipes.
In the prior art, the patent application with the publication number of CN112692065A discloses a high-strength thin-wall stainless steel hexagonal seamless pipe and a manufacturing method thereof, the hexagonal seamless pipe is formed by carrying out multi-pass cold rolling or cold drawing deformation and heat treatment on a pipe blank raw material, then carrying out two-step multi-roller precision cold rolling forming, and the cross section area of each part of the hexagonal seamless pipe is in a closed regular hexagon after forming, wherein the wall thickness is 1.0mm-3.5mm, the inner side distance is 40m-120mm, the surface roughness of the hexagonal seamless pipe after forming is less than or equal to 0.8 mu m, the wall thickness tolerance is +/-0.05 mm, the inner side distance tolerance is +/-0.10 mm, and the hexagonal seamless pipe has the characteristics of high surface finish and high dimensional accuracy.
The technology is limited to manufacturing technology of large-caliber equal-wall-thickness seamless tubes with hexagonal inner and outer surfaces, and the technology has the following problems for manufacturing high-precision outer hexagonal and inner circular stainless steel seamless tubes by the technology: the manufacturing method disclosed by the prior art is limited to manufacturing large-caliber hexagonal pipes, and the control of the size and the size precision of small-caliber hexagonal pipes cannot be implemented by using the method; the seamless pipe disclosed by the prior art is deformed from a circular pipe to a hexagonal pipe, the wall thickness on the same section is equal, the deformation is less than or equal to 15%, the seamless pipe can be formed, the requirement on the manufacturing deformation of the hexagonal pipe with unequal walls is large, the deformation is too small, and the deformation is insufficient and can influence the size and the precision of a final product; in addition, the final product of the seamless pipe is cold and is not subjected to heat treatment, and for some hexagonal pipes used in high-temperature environments, the pipe material can deform, so that the dimensional accuracy is affected.
Disclosure of Invention
The invention aims to solve the technical problem of providing a high-precision seamless pipe with an external hexagonal and an internal circular special-shaped section for nuclear power and a manufacturing method thereof,
the invention is realized by the following technical scheme.
The high-precision seamless pipe with the outer hexagonal and inner circular special-shaped cross section for nuclear power is characterized in that the pipe is made of stainless steel or corrosion resistant alloy with the elongation rate of more than 35%; the outer distance between the two sides is 10 mm-68 mm, and the deviation of the outer distance between the two sides is +/-0.05 mm; the diameter of the inner circle is 9 mm-66 mm, and the deviation of the diameter of the inner circle is +/-0.05 mm.
As a further improvement of the present invention, the surface roughness Ra is less than or equal to 0.8 μm.
The outer hexagonal inner circular tube has smaller size, higher requirement on dimensional accuracy and more requirement on dimensional parameters, is easier to assemble, and increases the application range of the tube; meanwhile, the finished product is subjected to solution heat treatment in a manufacturing method, and the elongation rate of the pipe is more than 35%, so that the pipe has excellent comprehensive mechanical properties and is suitable for use in a high-temperature environment.
The manufacturing method of the high-precision seamless pipe with the outer hexagonal and inner circular special-shaped cross section for the nuclear power is characterized by comprising the following steps of:
step 01: adopting a hot extrusion process to manufacture the bar material into a tube blank;
step 1: cold rolling the tube blank at high speed by two rollers with multiple passes to prepare a middle product round tube;
step 2: carrying out heat treatment on the intermediate round tube in each pass cold state, and adjusting the mechanical properties of the intermediate round tube;
step 3: finishing the deformation process from the round tube of the intermediate product to the seamless tube with the outer hexagonal and the inner circular special-shaped section by adopting three-roller finish rolling;
step 4: carrying out solution heat treatment on the cold seamless pipe with the outer hexagon and the inner circle and the special-shaped cross section, and then carrying out cooling treatment;
step 5: and (3) adopting a straightener to carry out orthopedic treatment on the seamless pipe with the special-shaped section of the outer hexagonal inner circle.
Step 6: cleaning and inspecting finished products.
In the manufacturing method, the deformation process of deforming the intermediate circular tube into the seamless tube with the outer hexagonal and the inner circular special-shaped cross section is a core step in step 3, and the basis and key points for implementing the deformation process are that the size indexes of the intermediate circular tube are defined according to the specification of a finished product.
Wherein, the external diameter D0 (mm) design requirement of intermediate product pipe: in order to ensure the forming of the outer hexagon of the pipe, the circumference L0 (mm) of the round pipe of the intermediate product is larger than the circumference L1 (mm) of the formed seamless pipe with the special-shaped section of the outer hexagon and the inner circle, namely the formed pipe,
namely: l0=μl1
π*D0=μ*2√3*D1 →
D0=1.1μ*D1
Wherein: mu is a deformation constant, and 1.0-1.5 can be taken; the deformation amount and the convenience of forming the outer diameter of the round pipe of the intermediate product are specifically selected, and the larger the required deformation amount is, the larger the mu selected numerical value is under the condition of meeting the capacity of the rolling mill.
D0 is the outer diameter of the round tube of the intermediate product, and the unit is mm;
d1 is the opposite side distance of the forming tube in mm.
Wall thickness S0 (mm) design requirement of the intermediate round tube: in order to ensure that the pipe is fully deformed, the inner circle is filled with complete grooves, and the wall thickness of the round pipe of the intermediate product is larger than the maximum wall thickness S1max (mm) of the forming pipe.
Namely: s0 > s1max=d1/≡3-D1/2- Δs1, Δs1=0.1r.
Wherein: s0 is the wall thickness of the middle product circular tube, and the unit is mm;
s1max is the maximum wall thickness of the formed pipe, and the unit is mm;
d1 is the opposite side distance of the forming tube, and the unit is mm;
d1 is the inner diameter of the forming tube, and the unit is mm;
Δs1 is a small value of the maximum wall thickness of the formed tube and the actual size, in mm, due to the presence of the R angle; the R angle is 6 arc transition included angles of the hexagon outside the forming tube;
r is the radius value of an included angle arc (R angle for short) of the forming tube, and the unit is mm;
the deformation amount of the hexagonal pipe which is formed by one-time cold rolling is large and difficult, so that the specification of the intermediate round pipe is selected to be as low as possible under the condition that the basic rolling deformation capability is met.
In order to ensure uniformity in pipe forming, the requirements of straightness and torsion after forming are met, and the uneven wall thickness of the middle round pipe is required to be not more than 5% of the wall thickness.
For step 01:
and determining the specification and the size of the bar, the specification of the extruded tube blank and the cold rolling process of the intermediate product according to the specification of the intermediate product round tube determined by the final molding process parameter design, wherein the tube blank is formed by hot extrusion of the bar, the extrusion temperature is 1100-1250 ℃, and the extrusion speed is 100-200 mm/s. After extrusion, the tube blank is subjected to finishing treatments such as straightening, tube cutting, acid washing and the like.
The finished pierced billet is inspected and polished branch by branch, and the surface of the finished extruded pipe is free from defects such as cracks, burrs, folds, shrinkage holes, scars, unacceptable scratches, folds, pits, extrusion straight channels and the like, and is not allowed to have oxide skin, glass lubricant particles and other impurities, and is not allowed to have phenomena such as underacid, overacid, rust spots and the like. The outer diameter deviation of the finished extruded tube is +/-1% of the outer diameter, the wall thickness deviation is +/-10% of the wall thickness, and the wall thickness unevenness is not more than 80% of the wall thickness deviation. The straightness of the extruded tube is not more than 2mm/m so as to meet the feeding requirement of cogging and cold rolling.
For step 1:
the extruded tube blank is prepared by multi-pass two-roller high-speed cold rolling, the deformation of the intermediate product of the two-roller cold rolling is set to be 50% -80%, the feeding amount is controlled to be 1-4 mm/time, and the rolling mill speed is controlled to be 60-200 times/min.
The inner and outer surfaces of the rolled middle round tube are clean, and defects such as cracks, folding, scratches, pits and the like which affect the subsequent finish rolling cannot exist, and the roughness Ra of the inner and outer surfaces is not more than 1.60 mu m. The uneven wall thickness of the middle circular tube does not exceed 5% of the wall thickness, and a solid foundation is laid for the contour index of the outer hexagonal inner circular seamless tube obtained by subsequent finish rolling to be qualified.
For step 2:
the intermediate heat treatment process temperature of each pass is 1050-1150 ℃, so that the intermediate round tube is well shaped, the elongation after fracture is controlled to be more than 40%, the subsequent final shaping is facilitated, the crystal grains of the tube are fully crushed by fully solid solution, the grain size grade is controlled to be 4.0-8.0, the subsequent heat treatment process is flexibly customized, and the excellent structure and performance are obtained.
For step 3:
the deformation process is a key step of the method, each size index is strictly controlled through final forming process parameter design, and a three-roller finish rolling is adopted to finally form the intermediate round tube into the high-precision outer hexagonal seamless tube with the irregular inner circular wall.
Because three-roller finish rolling is adopted to directly form the outer hexagonal and inner circular tube from the circular tube once, the required deformation is relatively large, and if the deformation is too small, the inner circular metal flow is insufficient, and rolling defects are easy to generate; the larger the deformation, the larger the required rolling force, and the less the rolling force of the finishing mill, the pipe is blocked, so that the inner surface pipe is scratched, and the reasonable final forming deformation is 30% -80%. The recommended cold rolling speed is 15-60 n/min, and the feeding amount is 1.0-3.0 mm/n. Designing a proper tool and die according to parameters, and simultaneously controlling the dimensions of outer opposite edge distance, inner diameter, R angle, minimum wall thickness of a plane center point, maximum wall thickness at the R angle, edge straightness, torsion, surface profile, pipe end perpendicularity and the like, so as to ensure that the technical requirements are met; the rolled pipe should be degreased and cleaned in time to ensure the cleanness of the inner and outer surfaces.
According to the requirement of the intermediate round tube and the selection of the deformation, the cold rolling mode and the type of the rolling mill are determined, and three roller finishing mill types LD15, LD30 or LD60 are generally selected for rolling.
For step 4:
solution heat treatment is also an important step in the present application. The wall thickness of the whole cross section of the cold-state outer hexagonal inner circular tube is inconsistent, the tissues at different wall thicknesses are uniform and consistent under the same heat treatment condition, the customization requirement on the heat treatment is high, and the bright heat treatment or the vacuum heat treatment can be adopted for solid solution. Specifically, a bright heat treatment or a vertical vacuum heat treatment may be used.
If bright heat treatment is adopted, the inert protective gas is hydrogen with the purity of more than 99.95%, so that the finished pipe has better mechanical property, the oxidation discoloration phenomenon of the inner surface and the outer surface of the pipe is avoided, and the pipe has better surface quality. The annealing temperature is 980-1100 ℃, the heat preservation time is determined according to the wall thickness of the pipe, the heat preservation time is generally ensured to be 1.0-6.0 min/mm of the maximum wall thickness of the pipe, the selection value is determined according to the mechanical property index required by the finished product, the higher the required strength of the finished product is, the finer the grain structure is, the lower the selection value is, and the cooling mode adopts rapid air cooling.
If vertical vacuum heat treatment is adopted, the vacuum annealing temperature is 980-1100 ℃, the heat preservation time is 1.0-6.0 min/mm of the maximum wall thickness of the pipe, and the cooling mode adopts argon filling quick cooling, so that the uniform grain structure of the pipe is ensured; the vacuum degree is not lower than 10 < -2 > Pa in the heating process so as to prevent the surface from oxidative discoloration; by adopting a vertical hanging loading mode, the two ends of the head and the tail of the pipe are fixed on the tool by using stainless steel wires, and the bending deformation of the pipe can be reduced due to the influence of gravity, so that the subsequent finishing treatment is facilitated.
For step 5:
and (3) finishing and cleaning the heat-treated pipe by adopting a straightener, so as to ensure that the external dimension, the surface quality and the cleanliness meet the technical requirements.
The invention has the beneficial effects that:
(1) An advanced size calculation formula is provided, so that the specification range and size control can be conveniently determined;
(2) The process is optimized and designed reasonably, and the cold-working molding requirement of the stainless steel seamless pipe with the outer hexagon and the inner circle is met;
(3) In the cold rolling process, dimensional parameters such as outer opposite edge distance, inner diameter, R angle, minimum wall thickness of a plane center point, maximum wall thickness at the R angle, edge straightness, torsion, surface profile, pipe end perpendicularity and the like are simultaneously controlled, so that technical requirements are met;
(4) And the design is reasonable, and the solution heat treatment process parameters are designed to ensure that the product performance meets the technical requirements.
Drawings
Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings, to facilitate understanding of the objects and advantages of the present invention, wherein:
FIG. 1 is a schematic view of a high-precision outer hexagonal inner circular irregular section seamless tube for nuclear power.
Detailed Description
The invention is described in further detail below with reference to the drawings and the examples.
The terms of orientation such as up, down, left, right, front, rear, front, back, top, bottom, etc. mentioned or possible in this specification are defined with respect to the configurations shown in the drawings, and the terms "inner" and "outer" refer to the relative concepts of the terms toward or away from the geometric center of a particular component, respectively, and thus may be changed accordingly depending on the location and use state of the component. These and other directional terms should not be construed as limiting terms.
As shown in fig. 1, the high-precision seamless pipe with the outer hexagonal and inner circular special-shaped cross section for nuclear power has the outer butt edge distance d1=24.0 mm and the deviation is +/-0.05 mm; the inner diameter d1=21.6 mm, deviation ±0.05mm; minimum wall thickness S1min=1.15 mm, length L3=1000 mm, surface profile degree 0.05mm, angle radius value R of hexagonal pipe external angle is less than or equal to 3mm. Specific methods of preparation for this exemplary target product are described below. Other specifications of high-precision hexagonal pipes can be implemented by referring to the method, and specific cold rolling, solution treatment and straightening processes can be adaptively adjusted within the scope of the patent.
Step 01: the bar material made of 316H stainless steel is selected, and the chemical components of the bar material accord with corresponding regulations in GB/T20878-2007 standard of stainless steel and heat-resistant steel brand and chemical components. And (3) adopting a hot extrusion process to manufacture the bar phi 204mm into a tube blank phi 78mm, wherein the extrusion temperature is about 1150-1200 ℃ and the extrusion speed is 150mm/s.
The extruded pipe is subjected to finishing treatments such as straightening, pipe cutting, acid washing and the like, and finished pierced billets are inspected and polished one by one; the surface should be free of cracks, burrs, folds, shrinkage cavities, scarring, unacceptable scratches, folds, craters, extrusion straight lines, and the like, and should not allow for the presence of scale, glass lubricant particles, and other impurities, and should not allow for the presence of underacid, peracids, and rust spots. The inner and outer surfaces of the intermediate round tube are required to be clean and bright, and defects such as cracks, folds, scratches, pits and the like which influence the subsequent cold drawing cannot exist. The roughness Ra of the inner and outer surfaces of the round tube of the intermediate product is not more than 0.80um.
Step 1: the tube blank is subjected to two-pass high-speed cold rolling to form an intermediate round tube, the high-speed cold rolling deformation is set to be 50-70%, the intermediate heat treatment process is set to be 1050-1100 ℃, the yield strength of the tube is controlled to be 250-300 MPa, the elongation after break is more than 50%, and the subsequent finish rolling forming is facilitated.
Outer diameter of intermediate round tube: d0 The deformation constant μ is taken as 1.1, i.e., d0=29.04 mm=1.1 μ×d1. In order to facilitate the size control, 29mm is taken according to the practical situation D0, and the tolerance is controlled to be +/-0.1 mm. Wall thickness of intermediate round tube: s0 > s1max=d1/≡3-D1/2- Δs1, Δs1=0.1r, i.e. s0 > 2.75mm. In order to facilitate the dimensional control, the tolerance is controlled to be + -0.05 mm according to practical conditions s0=2.8mm. The uneven wall thickness is controlled within 0.05mm; the relative cold rolling deformation is about 40%; the length of the round tube of the intermediate product is about 800 mm.
Step 2: and carrying out heat treatment on the intermediate round tube in each pass cold state, and adjusting the mechanical properties of the intermediate round tube. The intermediate heat treatment process temperature of each pass is 1100 ℃, so that the intermediate round tube is well shaped, the elongation after fracture is controlled to be more than 40%, the crystal grains of the tube are fully crushed by fully solid solution, and the grain size grade is controlled to be 7.0.
Step 3: the intermediate round tube phi 29 multiplied by 2.8mm is subjected to final cold working by adopting a finish rolling process to form the seamless tube with 24mm butt edge distance and 21.6mm inner diameter and outer hexagon and inner circle. And determining a tool and a die required by rolling through cold deformation process design: roller, plug, slideway, etc. The tool and die are assembled on a rolling mill, and then the hexagonal pipe is rolled. In the cold rolling process, the inner surface and the outer surface are fully lubricated by adopting rolling oil, the cold rolling speed is not too high due to larger deformation, the feeding amount is not too high, the pipe is easy to scratch, the surface quality of a final finished product is not influenced, the recommended cold rolling speed is 30 n/min, and the feeding amount is 1.5 mm/n. The rolled pipe should be degreased and cleaned in time to ensure the cleanness of the inner and outer surfaces.
Step 4: the finished product heat treatment adopts a protective atmosphere bright annealing furnace to carry out solid solution treatment, the set temperature is 1050 ℃, the heat preservation time is 3min, the protective atmosphere is hydrogen, the purity is more than 99.95%, and the dew point of an air source is less than or equal to minus 50 ℃. And the solid solution is sufficient in the heat treatment process of the finished pipe, the structure is uniform, and the grain size is controlled at 7.0-8.0 level. The finished pipe is ensured to have higher mechanical property, the oxidation discoloration phenomenon of the inner surface and the outer surface of the pipe is avoided, and the pipe is ensured to have better surface quality. And finishing the heat-treated pipe.
Step 5: and detecting the surface quality, the organization and the size of the finished product hexagonal pipe after sizing, wherein the result is as follows:
1) Surface quality
The technical requirements are as follows:
the surface of the pipe material must not be provided with oxidation color, oil, or other lubricant, metal fragments or other foreign matters, cracks, pits, oxide films, sand holes or other defects which are unfavorable for the use of the pipe material;
the roughness Ra of the inner and outer surfaces of the finished product is less than or equal to 0.8 mu m.
Detection result: surface roughness ra=0.4 μm, and surface quality meets technical requirements.
2) Organization and Properties
The technical requirements are as follows:
the grain size is required to be 7 grade or finer, the uniform grain level difference of each part structure is not more than 1 grade, and the high-temperature tensile test at 650 ℃ requires that the tensile strength Rm is not less than 332MPa, the yield strength RP0.2 is not less than 108MPa and the section elongation A is not less than 30 percent.
Detection result:
the grain size is 8.0-8.5 grade; tensile strength rm=610 MPa, yield strength RP 0.2=300 MPa, section elongation a=58.0% in room temperature tensile test; tensile strength rm=372 MPa, yield strength RP 0.2=137 MPa, section elongation a=48.0% in a 650 ℃ high temperature tensile test. All meet the technical condition requirements.
3) Size of the device
The technical requirements are as follows:
edge distance: 24+ -0.05 mm; deviation of inner diameter: 21.6+ -0.05 mm; the minimum wall thickness is more than or equal to 1.15mm; the surface profile is less than or equal to 0.05mm, the port perpendicularity is less than or equal to 0.05mm, the angle radius value of the external angle is less than or equal to 3mm, and the length is 1000+/-0.5 mm.
Detection result:
opposite edge distance=24.05-23.97 mm; minimum wall thickness = 1.20-1.26 mm; inner diameter = 21.65-21.56 mm; length = 1000.5mm; face profile = 0.05mm; port perpendicularity = 0.03mm; the value r=3mm of the angular radius of the external corner of the hexagonal tube. All meet the technical condition requirements.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme recorded in each embodiment can be modified or part of technical features in the technical scheme can be replaced equivalently; such modifications and substitutions do not depart from the spirit of the invention.
Claims (9)
1. The manufacturing method of the high-precision seamless pipe with the outer hexagonal and inner circular special-shaped cross section for the nuclear power is characterized by comprising the following steps of:
step 1: cold rolling the tube blank at high speed by two rollers with multiple passes to prepare a middle product round tube;
D0=1.1μ*D1；
d0 is the outer diameter of the middle round tube, D1 is the butt pitch of the formed seamless tube with the outer hexagonal and inner circular special-shaped cross section, μ is the deformation constant, μ is 1.0-1.5;
s0 is the wall thickness of the middle round tube, S1max is the maximum wall thickness of the forming tube, D1 is the opposite side distance of the forming tube, D1 is the inner diameter of the forming tube, and r is the radius value of the included angle arc of the forming tube;
step 2: carrying out heat treatment on the intermediate round tube in each pass cold state, and adjusting the mechanical properties of the intermediate round tube;
step 3: finishing the deformation process from the round tube of the intermediate product to the seamless tube with the external hexagonal and the internal circular special-shaped section by adopting three-roller finish rolling, wherein the deformation amount of the three-roller finish rolling deformation process is 30% -80%, the cold rolling speed is 15-60 times/min, and the feeding amount is 1.0-3.0 mm/time;
step 4: the cold seamless pipe with the special-shaped cross section of the outer hexagon and the inner circle is firstly subjected to solution heat treatment and then is subjected to cooling treatment.
2. The method for manufacturing the seamless pipe with the high-precision outer hexagon and inner circle special-shaped section for the nuclear power, which is disclosed in claim 1, is characterized in that in the step 1, the deformation of the two-roller high-speed cold rolling is 50% -80%, the feeding amount is controlled to be 1-4 mm/time, and the rolling mill speed is controlled to be 60-200 times/min.
3. The method for manufacturing the seamless tube with the high-precision outer hexagon and inner circle special-shaped section for the nuclear power, which is disclosed in claim 1, is characterized in that in the step 2, the temperature of heat treatment of the intermediate round tube in each pass cold state is 1050-1150 ℃, and the grain size grade is controlled to be 4.0-8.0.
4. The method for manufacturing the seamless tube with the high-precision outer hexagon and inner circle special-shaped section for nuclear power according to claim 1, wherein the three-roller finish rolling in the step 3 is a three-roller finishing mill of model LD15, model LD30 or model LD 60.
5. The method for manufacturing a seamless tube with a high-precision outer hexagonal inner circular special-shaped section for nuclear power according to claim 1, wherein the solution heat treatment in the step 4 is a bright heat treatment; hydrogen with purity higher than 99.95% is used as inert gas for protection, the annealing temperature is 980-1100 ℃, and the heat preservation time is 1.0-6.0 min/mm of the maximum wall thickness of the forming tube; the cooling treatment adopts rapid air cooling.
6. The method for manufacturing the high-precision outer hexagonal inner circular irregular section seamless pipe for nuclear power according to claim 1, wherein the solution heat treatment in the step 4 is vertical vacuum heat treatment; vacuum annealing temperature is 980-1100 ℃, and heat preservation time is the maximum wall thickness of the pipe (1.0-6.0) min/mm; argon filling rapid cooling is adopted for cooling treatment.
7. The method for manufacturing a high-precision outer hexagonal inner circular irregularly-shaped cross-section seamless pipe for nuclear power according to claim 1, further comprising the step 5 of: and (3) adopting a straightener to carry out orthopedic treatment on the seamless pipe with the special-shaped section of the outer hexagonal inner circle.
8. The method for manufacturing the high-precision seamless tube with the outer hexagonal inner circular special-shaped section for nuclear power according to claim 1, wherein the step 1 is further preceded by the step 01 of: and (5) manufacturing the bar material into a tube blank by adopting a hot extrusion process.
9. The method for manufacturing the seamless pipe with the high-precision outer hexagonal inner circular special-shaped cross section for the nuclear power according to claim 8, wherein in the step 01, the extrusion temperature of the hot extrusion process is 1100 ℃ to 1250 ℃ and the extrusion speed is 100-200 mm/s.
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