阅读说明：本技术 一种核电用高精度外六角内圆异形截面无缝管的制造方法 (Manufacturing method of high-precision outer hexagonal and inner circular seamless tube with special-shaped cross section for nuclear power ) 是由 王涛 蔡志刚 杨红 周宇宾 张耀耀 马蓉丽 罗霞 卢培民 李欢妮 徐利苹 于 2021-06-30 设计创作，主要内容包括：本发明公开了一种核电用高精度外六角内圆异形截面无缝管,其特征在于,其材质为延伸率＞35%不锈钢或者耐蚀合金；外对边距10mm～68mm,外对边距偏差±0.05mm；内圆直径9mm～66mm,内圆直径偏差±0.05mm。本发明还公开了该核电用高精度外六角内圆异形截面无缝管的制备方法。(The invention discloses a high-precision outer hexagonal inner circular special-shaped section seamless tube for nuclear power, which is characterized by being made of stainless steel or corrosion-resistant alloy with the elongation rate of more than 35%; the outer edge distance is 10 mm-68 mm, and the deviation of the outer edge distance is +/-0.05 mm; the diameter of the inner circle is 9 mm-66 mm, and the diameter deviation of the inner circle is +/-0.05 mm. The invention also discloses a preparation method of the high-precision seamless tube with the outer hexagon and the inner circle special-shaped cross section for nuclear power.)

1. A nuclear power high-precision outer hexagonal inner circular special-shaped section seamless tube is characterized by being made of stainless steel or corrosion-resistant alloy with the elongation rate of more than 35%; the outer edge distance is 10 mm-68 mm, and the deviation of the outer edge distance is +/-0.05 mm; the diameter of the inner circle is 9 mm-66 mm, and the diameter deviation of the inner circle is +/-0.05 mm.

2. The high-precision outer hexagonal inner circular irregular cross-section seamless tube for nuclear power according to claim 1, characterized in that the surface roughness Ra is less than or equal to 0.8 μm.

3. The manufacturing method of the nuclear power high-precision seamless tube with the outer hexagon and the inner circle special-shaped cross section as claimed in claim 1 or 2, characterized by comprising the following steps:

step 1: the tube blank is subjected to multi-pass two-roller high-speed cold rolling to be made into an intermediate round tube;

D0=1.1μ*D1；

d0 is the outer diameter of the intermediate circular tube, D1 is the opposite side distance of the formed tube with the outer hexagon and the inner circle special-shaped section, namely the formed tube, and mu is 1.0-1.5;

S0＞S1max =D1/√3-d1/2 -ΔS1，ΔS1=0.1r；

s0 is the wall thickness of the intermediate circular tube, S1max is the maximum wall thickness of the forming tube, D1 is the opposite edge 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 pipe in the cold state of each pass, and adjusting the mechanical property of the intermediate round pipe;

and step 3: finishing the deformation process from the intermediate round tube to the outer hexagonal and inner circular seamless tube with the special-shaped section by three-roller finish rolling;

and 4, step 4: the cold seamless tube with the outer hexagon and the inner circle special-shaped section is subjected to solution heat treatment and then cooling treatment.

4. The manufacturing method of the high-precision seamless tube with the outer hexagon and the inner circle special-shaped section for nuclear power as claimed in claim 3, wherein in the step 1, the deformation amount 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 speed is controlled to be 60-200/min.

5. The manufacturing method of the nuclear power seamless tube with the high-precision outer hexagon and inner circle special-shaped section, as claimed in claim 3, is characterized in that in the step 2, the temperature of the heat treatment of the cold-state intermediate product circular tube in each pass is 1050-1150 ℃, and the grain size grade is controlled to be 4.0-8.0.

6. The manufacturing method of the nuclear power high-precision outer hexagonal and inner circular irregular section seamless tube according to claim 3, wherein in the step 3, the deformation amount in the three-roll finish rolling deformation process is 30% -80%, the cold rolling speed is 15-60 n/min, and the feeding amount is 1.0-3.0 mm/n.

7. The manufacturing method of the nuclear power seamless tube with the high-precision outer hexagon and inner circle special-shaped section, as claimed in claim 6, is characterized in that the three-roll finishing mill of LD15 or LD30 or LD60 type is selected for the three-roll finishing rolling in the step 3.

8. The manufacturing method of the high-precision seamless tube with the hexagonal outside and the special-shaped inside cross section for nuclear power as claimed in claim 3, wherein the solution heat treatment of step 4 is a bright heat treatment; hydrogen with the purity of more than 99.95 percent is used as inert gas protection, the annealing temperature is 980-1100 ℃, and the heat preservation time is the maximum wall thickness (1.0-6.0) min/mm of the forming pipe; and rapid air cooling is adopted for cooling treatment.

9. The manufacturing method of the nuclear power seamless tube with the high-precision outer hexagon and inner circle special-shaped section as claimed in claim 3, wherein the solution heat treatment in the step 4 is vertical vacuum heat treatment; the vacuum annealing temperature is 980-1100 ℃, and the heat preservation time is the maximum wall thickness of the pipe (1.0-6.0) min/mm; the cooling treatment adopts argon filling and quick cooling.

10. The manufacturing method of the nuclear power high-precision seamless tube with the outer hexagon and the inner circle special-shaped section as claimed in claim 3, characterized by further comprising the step 5: and (3) adopting a straightening machine to shape the seamless tube with the outer hexagonal and inner circular special-shaped section.

11. The manufacturing method of the nuclear-power high-precision seamless tube with the outer hexagon and the inner special-shaped cross section as claimed in claim 3, wherein the step 1 is preceded by the step 01: the bar is made into a tube blank by adopting a hot extrusion process.

12. The manufacturing method of the nuclear power high-precision seamless tube with the outer hexagon and the inner circle special-shaped section as claimed in claim 11, wherein in the step 01, the extrusion temperature of the hot extrusion process is 1100-1250 ℃, and the extrusion speed is 100-200 mm/s.

Technical Field

The invention relates to a high-precision seamless tube with an outer hexagon and an inner circle special-shaped section for nuclear power and a manufacturing method thereof, belonging to the technical field of special alloy special-shaped section seamless tube preparation in new materials.

Background

The traditional manufacturing process of the outer hexagonal inner round seamless tube adopts multi-pass cold rolling and multi-pass cold drawing forming or adopts a hot working process shaping and multi-pass cold drawing size determining process, and the technical schemes have the advantages of more process passes, low production efficiency and low size precision of the produced product, and cannot meet the production requirements of high-precision outer hexagonal and inner round tubes.

In the prior art, the patent application with the publication number of CN112692065A discloses a high-strength thin-wall stainless steel hexagonal seamless tube and a manufacturing method thereof, the hexagonal seamless tube is formed by multiple cold rolling or cold drawing deformation and heat treatment of tube blank raw materials and two-step multiple-roller precision cold rolling, the cross section area of each part of the hexagonal seamless tube is a closed regular hexagon after forming, wherein the wall thickness is 1.0mm-3.5mm, the internal pair of edge distances is 40m-120mm, the surface roughness of the hexagonal seamless tube after forming is less than or equal to 0.8 mu m, the wall thickness tolerance is +/-0.05 mm, the internal pair of edge distances is +/-0.10 mm, and the high-strength thin-wall stainless steel hexagonal seamless tube has the characteristics of high surface finish and high dimensional precision.

The application patent technology relates to a manufacturing technology of a hexagonal equal-wall-thickness seamless tube limited to large-caliber inside and outside, and the application patent technology has the following problems for manufacturing high-precision stainless steel seamless tubes with an outer hexagonal shape and an inner circular shape, which are mentioned in the patent technology: the manufacturing method disclosed by the prior art is limited to manufacturing large-caliber hexagonal tubes, and the size and size precision control of the small-caliber hexagonal tubes 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 high, the deformation is too small, and the size and the precision of a final product can be influenced due to insufficient deformation; in addition, the seamless tube is not heat-treated in a cold state, and the tube material is deformed in some hexagonal tubes used in a high-temperature environment, thereby affecting the dimensional accuracy.

Disclosure of Invention

The invention aims to solve the technical problem of providing a high-precision seamless tube with an outer hexagonal shape and an inner circular special-shaped section for nuclear power and a manufacturing method thereof,

the invention is realized by the following technical scheme.

A nuclear power high-precision outer hexagonal inner circular special-shaped section seamless tube is characterized by being made of stainless steel or corrosion-resistant alloy with the elongation rate of more than 35%; the outer edge distance is 10 mm-68 mm, and the deviation of the outer edge distance is +/-0.05 mm; the diameter of the inner circle is 9 mm-66 mm, and the diameter deviation of the inner circle is +/-0.05 mm.

As a further improvement of the invention, the surface roughness Ra is less than or equal to 0.8 mu m.

The outer hexagonal inner circular pipe has smaller size, higher requirement on size precision and more requirement on size parameters, is easier to assemble, and increases the application range of the pipe; meanwhile, the finished product adopts solution heat treatment in the manufacturing method which is described later, the elongation of the pipe is more than 35 percent, so that the pipe has excellent comprehensive mechanical property and is suitable for being used in a high-temperature environment.

A manufacturing method of a nuclear power high-precision seamless tube with an outer hexagon and an inner circle special-shaped section is characterized by comprising the following steps:

step 01: manufacturing the bar into a tube blank by adopting a hot extrusion process;

step 1: the tube blank is subjected to multi-pass two-roller high-speed cold rolling to be made into an intermediate round tube;

step 2: carrying out heat treatment on the intermediate round pipe in the cold state of each pass, and adjusting the mechanical property of the intermediate round pipe;

and step 3: finishing the deformation process from the intermediate round tube to the outer hexagonal and inner circular seamless tube with the special-shaped section by three-roller finish rolling;

and 4, step 4: carrying out solution heat treatment on the cold seamless tube with the outer hexagon and the inner circle special-shaped section, and then carrying out cooling treatment;

and 5: and (3) adopting a straightening machine to shape the seamless tube with the outer hexagonal and inner circular special-shaped section.

Step 6: cleaning and finished product inspection.

In the manufacturing method, the step 3 of deforming the intermediate product circular tube into the seamless tube with the outer hexagonal and inner circular special-shaped cross section is a core step, and the basis and key point for implementing the step are that the size indexes of the intermediate product 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 outer hexagon forming of the pipe, the perimeter L0 (mm) of the round pipe of the intermediate product is larger than the perimeter L1 (mm) of the formed seamless pipe with the outer hexagon and the inner circle special-shaped section, namely the formed pipe,

namely: l0= μ L1

π*D0=μ*2√3*D1 →

D0=1.1μ*D1

In the formula: mu is a deformation constant, and can be 1.0-1.5; specifically, the deformation and the outer diameter forming convenience of the intermediate round tube are selected, and the larger the required deformation is, the larger the value of mu is, under the condition of meeting the rolling mill capability.

D0 is the outer diameter of the round tube of the middle product, and the unit is mm;

d1 is the distance between opposite sides of the forming tube in mm.

The wall thickness S0 (mm) design requirement of the intermediate round tube is as follows: in order to ensure that the pipe is fully deformed, the inner circle is completely filled without a groove, and the wall thickness of the intermediate circular pipe is larger than the maximum wall thickness S1max (mm) of the forming pipe.

Namely: s0 > S1max = D1/√ 3-D1/2- Δ S1, Δ S1=0.1 r.

In the formula: s0 is the wall thickness of the middle round tube, and the unit is mm;

s1max is the maximum wall thickness of the forming tube, and the unit is mm;

d1 is the opposite side distance of the forming tube, and the unit is mm;

d1 is the inside diameter of the forming tube in mm;

Δ S1 is the minimum value of the maximum wall thickness and the actual size of the forming tube in mm due to the existence of the R angle; the R angle is an included angle formed by 6 arc transitions of the hexagon outside the forming tube;

r is the radius value of the included angle arc (R angle for short) of the forming tube, and the unit is mm;

since the hexagonal tube is difficult to be deformed by the one-time cold rolling, the specification of the intermediate round tube is selected to satisfy the basic rolling deformation capability, and S0 takes the lower limit as much as possible.

In order to ensure the uniformity of the pipe during forming and the requirements of straightness and torsion after forming, the uneven wall thickness of the intermediate product circular pipe needs to be ensured not to exceed 5 percent of the wall thickness.

For step 01:

the specification and the size of a bar, the specification of an extruded tube blank and the process of intermediate cold rolling are determined according to the specification of an intermediate round tube designed and determined according to the technological parameters of final forming, 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 pickling and the like.

The finished pierced billet is inspected and polished one by one, the finished extruded tube surface has no defects of cracks, burrs, folds, shrinkage cavities, scabs, unacceptable scratches, folds, indentation, extrusion straight lines and the like, oxide skins, glass lubricant particles and other impurities are not allowed, and the phenomena of acid deficiency, peracid, rusty spot and the like are not allowed. The deviation of the outer diameter of the finished extruded tube is +/-1% of the outer diameter, the deviation of the wall thickness is +/-10% of the wall thickness, and the deviation of the wall thickness is not more than 80% of the wall thickness. 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 in the two-roller cold rolling is set to be 50% -80%, the feeding amount is controlled to be 1-4 mm/time, and the speed of the rolling mill is controlled to be 60-200 times/min.

The inner surface and the outer surface of the rolled middle circular tube are clean, the defects of cracks, folding, scratches, pits and the like which influence the subsequent finish rolling cannot exist, and the roughness Ra of the inner surface and the outer surface is not more than 1.60 um. The uneven wall thickness of the middle round tube is not more than 5% of the wall thickness, and a solid foundation is laid for the qualified profile index of the outer hexagonal and inner round seamless tube obtained by subsequent finish rolling.

For step 2:

the temperature range of the intermediate heat treatment process in each pass is 1050-1150 ℃, so that the intermediate circular tube is well shaped, the elongation after fracture is controlled to be more than 40%, the subsequent final forming is facilitated, the grains of the tube are fully crushed by full solid solution, the grain size grade is controlled to be 4.0-8.0, the subsequent heat treatment process is convenient to flexibly customize, and 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 the intermediate round tube is finally formed into the special-shaped section seamless tube with high-precision outer hexagon and inner circular unequal wall by three-roll finish rolling.

Because the three-roller finish rolling is adopted to directly form the circular tube into the outer hexagonal and inner circular tubes at one time, the required deformation is relatively large, if the deformation is too small, the metal flow of the inner circle is insufficient, and the rolling defect is easy to generate; the deformation is too large, the required rolling force is larger, the rolling force of the finishing mill is generally small, the pipe can be clamped, 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 such as the outer edge distance, the inner circle diameter, the R angle, the minimum wall thickness of the plane central point, the maximum wall thickness of the R angle, the edge straightness, the torsion, the surface profile degree, the pipe end verticality and the like 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 requirements 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 roll finishing mill types including LD15, LD30 and 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 outer hexagonal inner circular tube is not consistent, the tissues at different wall thicknesses are ensured to be uniform and consistent under the same heat treatment condition, the customization requirement on heat treatment is high, and bright heat treatment or vacuum heat treatment can be adopted for solid solution. Specifically, bright heat treatment or vertical vacuum heat treatment may be employed.

If the bright heat treatment is adopted, the inert protective gas is hydrogen with the purity of more than 99.95 percent, so that the finished pipe has better mechanical property, the oxidation and discoloration phenomena on the inner surface and the outer surface of the pipe are avoided, and the pipe has better surface quality. The annealing temperature is 980-.

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 and quick cooling to ensure that the grain structure of the pipe is uniform; the vacuum degree is not lower than 10-2Pa in the heating process so as to prevent the surface from oxidative discoloration; the vertical suspension feeding mode is adopted, the head end and the tail end of the pipe are fixed on a tool through stainless steel wires, and due to the influence of gravity, bending deformation of the pipe can be reduced, and subsequent finishing treatment is facilitated.

For step 5:

and (3) finishing and cleaning the heat-treated pipe by adopting a straightening machine to ensure that the overall 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 specification range and size control are convenient to determine;

(2) the reasonable process is optimized, and the cold working forming requirements of the stainless steel seamless pipe with the hexagonal outer shape and the circular inner shape are met;

(3) in the cold rolling process, dimensional parameters such as external edge distance, internal circle diameter, R angle, minimum wall thickness of plane central point, maximum wall thickness of R angle, edge straightness, torsion, surface profile degree, pipe end verticality and the like are controlled simultaneously, so that technical requirements are met;

(4) reasonable solution heat treatment process parameters are designed to ensure that the product performance meets the technical requirements.

Drawings

The preferred embodiments of the present invention will hereinafter be described in detail to facilitate understanding of the objects and advantages of the invention, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a high-precision seamless tube with an outer hexagon and an inner circle special-shaped cross section for nuclear power.

Detailed Description

The invention is explained in more detail below with reference to the drawings and exemplary embodiments.

The terms of orientation of up, down, left, right, front, back, top, bottom, and the like as referred to or as may be referred to in this specification are defined with respect to the configuration shown in the drawings, and the terms "inner" and "outer" refer to directions toward and away from the geometric center of a particular component and are relative terms, and thus may be changed accordingly depending on the position and the state of use of the particular component. Therefore, these and other directional terms should not be construed as limiting terms.

As shown in fig. 1, the high-precision outer hexagonal inner circular special-shaped section seamless tube for nuclear power has an outer edge distance D1=24.0mm and a deviation of ± 0.05 mm; inner circle diameter d1=21.6mm, deviation ± 0.05 mm; the minimum wall thickness S1min =1.15mm, the length L3=1000mm, the surface profile degree is 0.05mm, and the angle radius value R of the external angle of the hexagonal tube is less than or equal to 3 mm. The specific preparation method for the typical target product is as follows. The high-precision hexagonal pipes with other specifications can be implemented by referring to the method, and the specific processes of cold rolling, solution treatment and straightening can be adaptively adjusted within the scope of the patent.

Step 01: the rod material made of 316H stainless steel is selected, and the chemical components of the rod material accord with the corresponding regulations in the Standard GB/T20878-. The hot extrusion process is adopted to manufacture a tube blank phi 78mm from a bar phi 204mm, wherein the extrusion temperature is about 1150-1200 ℃, and the extrusion speed is 150 mm/s.

The extruded pipe needs to be subjected to finishing treatment such as straightening, pipe cutting, acid pickling and the like, and the finished pierced billets are inspected and polished one by one; the surface should be free of cracks, burrs, folds, shrinkage cavities, scabs, unacceptable scratches, folds, indentation, extrusion straight lines and other defects, and must not be free of scale, glass lubricant particles and other impurities, and free of the phenomena of acid deficiency, peracid, rust stains and the like. The inner and outer surfaces of the intermediate round tube need to be clean and bright, and the defects of cracks, folding, scratches, pits and the like which influence the subsequent cold drawing are avoided. The roughness Ra of the inner surface and the outer surface of the intermediate round tube is not more than 0.80 um.

Step 1: the tube blank is subjected to high-speed cold rolling for two passes to form an intermediate product circular 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 fracture is greater than 50%, and the subsequent finish rolling forming is facilitated.

Outer diameter of the intermediate round tube: d0=1.1 μ × D1, with a deformation constant μ of 1.1, i.e. D0=29.04 mm. For the convenience of size control, 29mm is taken according to the practical condition D0, and the tolerance is controlled to be +/-0.1 mm. Thickness of intermediate round tube: s0 > S1max = D1/√ 3-D1/2- Δ S1, Δ S1=0.1R, i.e. S0 > 2.75 mm. For the convenience of size control, according to the practical situation of S0=2.8mm, the tolerance is controlled to be +/-0.05 mm. The uneven wall thickness is controlled within 0.05 mm; the relative cold rolling deformation is about 40 percent; the length of the middle circular tube is about 800 mm.

Step 2: and carrying out heat treatment on the intermediate round pipe in the cold state of each pass, and adjusting the mechanical property of the intermediate round pipe. The temperature range of the intermediate heat treatment process in each pass is 1100 ℃, so that the intermediate circular tube is well shaped, the elongation after fracture is controlled to be more than 40%, the grains of the tube are fully crushed by full solid solution, and the grain size grade is controlled to be 7.0 grade.

And step 3: the intermediate round tube with the diameter of 29 multiplied by 2.8mm is finally cold-processed and formed into an external hexagonal and internal circular seamless tube with the edge distance of 24mm and the internal diameter of 21.6mm by adopting a finish rolling process. Determining a tool and a die required by rolling through cold deformation process design: rollers, rams, slides, etc. And (4) assembling the tool and the die on a rolling mill, and then rolling the hexagonal tube. In the cold rolling process, the inner surface and the outer surface are fully lubricated by using rolling oil, the deformation is large, the cold rolling speed is not too high, the feeding amount is not too large, the pipe is easy to scratch, the surface quality of a final finished product is not affected, 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.

And 4, step 4: the heat treatment of the finished product adopts a protective atmosphere bright annealing furnace for 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 percent, and the dew point of an air source is less than or equal to minus 50 ℃. The finished pipe is fully dissolved in the heat treatment process, the structure is uniform, and the grain size is controlled to be 7.0-8.0 grade. The high mechanical property of the finished pipe is ensured, the oxidation and color change phenomena of the inner surface and the outer surface of the pipe are avoided, and the good surface quality of the pipe is ensured. And finishing the heat-treated pipe.

And 5: and (3) detecting the surface quality, the structure and the size of the finished hexagonal pipe after sizing one by one, wherein the results are as follows:

1) surface quality

The technical requirements are as follows:

the surface of the pipe is free from oxidation color, oil or other lubricants, metal fragments or other foreign matters, cracks, pits, oxidation films, sand holes or other defects which are not beneficial to the use of the pipe;

the roughness Ra of the inner surface and the outer surface of the finished product is less than or equal to 0.8 mu m.

And (3) detection results: the surface roughness Ra =0.4 μm, and the surface quality meets the requirements of technical conditions.

2) Organization and Performance

The technical requirements are as follows:

the grain size is required to be 7 grade or finer, the uniform grain grade difference of each part tissue does not exceed 1 grade, and the 650 ℃ high-temperature tensile test requires that the tensile strength Rm is more than or equal to 332MPa, the yield strength RP0.2 is more than or equal to 108MPa, and the section elongation A is more than or equal to 30%.

And (3) detection results:

the grain size is 8.0-8.5 grade; tensile strength Rm =610MPa, yield strength RP0.2=300 MPa, elongation at break a =58.0% in a room-temperature tensile test; tensile strength Rm =372MPa, yield strength RP0.2=137MPa, and elongation at break A =48.0% in a high-temperature tensile test at 650 ℃. All meet the requirements of technical conditions.

3) Size of

The technical requirements are as follows:

edge distance alignment: 24 plus or minus 0.05 mm; inner diameter deviation: 21.6 plus or minus 0.05 mm; the minimum wall thickness is more than or equal to 1.15 mm; the surface profile degree is less than or equal to 0.05mm, the port verticality 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.

And (3) detection results:

the opposite edge distance is = 24.05-23.97 mm; the minimum wall thickness is = 1.20-1.26 mm; the inner diameter = 21.65-21.56 mm; length =1000.5 mm; face profile =0.05 mm; port verticality =0.03 mm; the value of the angular radius of the external angle of the hexagonal tube R =3 mm. All meet the requirements of technical conditions.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that: the technical solutions described in the foregoing embodiments can be modified, or some technical features can be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.