WO2023272609A1 - 一种核电用高精度外六角内圆异形截面无缝管及其制造方法 - Google Patents

一种核电用高精度外六角内圆异形截面无缝管及其制造方法 Download PDF

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WO2023272609A1
WO2023272609A1 PCT/CN2021/103690 CN2021103690W WO2023272609A1 WO 2023272609 A1 WO2023272609 A1 WO 2023272609A1 CN 2021103690 W CN2021103690 W CN 2021103690W WO 2023272609 A1 WO2023272609 A1 WO 2023272609A1
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Prior art keywords
inner circle
nuclear power
shaped cross
pipe
seamless pipe
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PCT/CN2021/103690
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English (en)
French (fr)
Inventor
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
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浙江久立特材科技股份有限公司
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Priority to PCT/CN2021/103690 priority Critical patent/WO2023272609A1/zh
Publication of WO2023272609A1 publication Critical patent/WO2023272609A1/zh

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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
    • 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
    • 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
    • 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
    • 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
    • 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

Definitions

  • the invention relates to a high-precision outer hexagonal inner circle special-shaped cross-section seamless pipe for nuclear power and a manufacturing method thereof, belonging to the technical field of preparation of special alloy special-shaped cross-section seamless pipes in new materials.
  • the traditional outer hexagonal inner circle seamless pipe manufacturing process adopts multi-pass cold rolling plus multi-pass cold drawing forming, or adopts thermal processing technology to set the shape and multi-pass cold drawing to determine the size.
  • Many, low production efficiency, and low dimensional accuracy of the produced products cannot meet the production needs of high-precision outer hexagonal and inner circular tubes.
  • the patent application with the publication number CN112692065A discloses a high-strength thin-walled stainless steel hexagonal seamless pipe and its manufacturing method. After cold drawing deformation and heat treatment, it is divided into two steps of multi-roller precision cold rolling forming. After forming, the cross-sectional area of the hexagonal seamless pipe is a closed regular hexagon, and the wall thickness is 1.0mm-3.5mm. The inner edge distance is 40m-120mm, the surface roughness of the hexagonal seamless pipe after forming is ⁇ 0.8 ⁇ m, the wall thickness tolerance is ⁇ 0.05mm, the inner edge distance tolerance is ⁇ 0.10mm, and it has the characteristics of high surface finish and high dimensional accuracy. Invention and preparation of high-strength thin-walled stainless steel hexagonal seamless pipes with flexible specifications of intermediate product round pipes and finished special-shaped pipes with high surface finish, high dimensional accuracy, and high strength.
  • the manufacturing method disclosed in this prior art is limited to the manufacture of large-diameter hexagonal pipes, and the size and dimensional accuracy control of small-diameter hexagonal pipes cannot be implemented using this method; the seamless pipe disclosed in this prior art is deformed from a circular pipe to For hexagonal tubes, the wall thickness on the same section is equal, and the deformation amount is less than 15%, and it can be formed.
  • the manufacturing deformation amount of hexagonal tubes with unequal walls is large, and the deformation amount is too small. Insufficient deformation will affect the final The size and precision of the product; in addition, the final product of the seamless pipe is cold without heat treatment. For some hexagonal pipes used in high temperature environments, the pipe will be deformed, which will affect the dimensional accuracy.
  • the technical problem to be solved by the present invention is to provide a high-precision outer hexagonal inner circle special-shaped cross-section seamless pipe for nuclear power and its manufacturing method.
  • the present invention is achieved through the following technical solutions.
  • a high-precision outer hexagonal inner circle special-shaped cross-section seamless pipe for nuclear power which is characterized in that its material is stainless steel or corrosion-resistant alloy with an elongation rate > 35%; the outer edge distance is 10mm ⁇ 68mm, and the outer edge distance deviation is ⁇ 0.05mm ; The diameter of the inner circle is 9mm ⁇ 66mm, and the deviation of the inner circle diameter is ⁇ 0.05mm.
  • the outer hexagonal inner round pipe of this application is smaller in size, requires higher dimensional accuracy, and requires more dimensional parameters, which makes it easier to assemble and increases the scope of application of the pipe; at the same time, the finished product is used in the manufacturing method described later.
  • Solution heat treatment the elongation of the pipe is more than 35%, so that the pipe has excellent comprehensive mechanical properties and is suitable for use in high temperature environments.
  • a method for manufacturing a high-precision outer hexagonal inner circle special-shaped cross-section seamless pipe for nuclear power characterized in that the steps include:
  • Step 01 Use the hot extrusion process to make the rod into a tube blank
  • Step 1 The tube blank is subjected to multi-pass two-roll high-speed cold rolling to make an intermediate product round tube;
  • Step 2 Carry out heat treatment on the cold intermediate tube of each pass to adjust the mechanical properties of the intermediate tube;
  • Step 3 Using three-roll finish rolling to complete the deformation process from the intermediate product round pipe to the outer hexagonal inner circle special-shaped cross-section seamless pipe;
  • Step 4 Perform solution heat treatment on the cold outer hexagonal inner circle special-shaped cross-section seamless pipe, and then perform cooling treatment;
  • Step 5 Use a straightening machine to perform straightening treatment on the hexagonal and inner circle special-shaped cross-section seamless pipe.
  • Step 6 Cleaning treatment and finished product inspection.
  • step 3 is the deformation process of deforming the intermediate product round pipe into an outer hexagonal inner circle special-shaped cross-section seamless pipe is the core step, and the basis and key point for implementing this step is to define the intermediate product circle according to the finished product specification The dimensions of the tube.
  • the outer diameter D0 (mm) design requirements of the intermediate product round tube in order to ensure the outer hexagonal forming of the pipe, the perimeter L0 (mm) of the intermediate product round tube should be larger than the formed outer hexagonal inner circle special-shaped cross-section seamless tube, that is Circumference L1 (mm) of the forming tube,
  • ⁇ is the deformation constant, which can be 1.0 ⁇ 1.5; it is selected according to the deformation amount and the convenience of forming the outer diameter of the intermediate tube. Under the condition of meeting the capacity of the rolling mill, the larger the required deformation amount, the higher the selected value of ⁇ . big.
  • D0 is the outer diameter of the intermediate tube, in mm
  • D1 is the distance across sides of the formed tube, in mm.
  • Design requirements for the wall thickness S0 (mm) of the intermediate product round pipe In order to ensure that the pipe is fully deformed and the inner circle is completely filled without grooves, the wall thickness of the intermediate product round pipe must be greater than the maximum wall thickness S1max (mm) of the formed pipe.
  • S0 is the wall thickness of the intermediate tube, in mm
  • S1max is the maximum wall thickness of the formed pipe, in mm
  • D1 is the distance across the sides of the forming tube, in mm
  • d1 is the inner diameter of the forming tube, in mm;
  • ⁇ S1 is the smaller value between the maximum wall thickness and the actual size of the formed tube due to the existence of the R angle, the unit is mm; the R angle is the included angle of the 6 outer hexagons of the formed tube in a circular arc transition;
  • r is the radius value of the included angle arc (referred to as R angle) of the formed pipe, in mm;
  • the uneven wall thickness of the intermediate product round pipe must be guaranteed not to exceed 5% of the wall thickness.
  • the specification size of the bar, the specification of the extruded tube blank, and the cold rolling process of the intermediate product are determined.
  • the tube blank is formed by hot extrusion of the bar material, and the extrusion temperature It is 1100°C to 1250°C, and the extrusion speed is 100 ⁇ 200mm/s. After extrusion, the tube billet needs finishing treatment such as straightening, pipe cutting, pickling, etc.
  • the surface of the trimmed extruded tubes should be free from cracks, burrs, folds, shrinkage cavities, scabs and unacceptable scratches, folds, pits, Defects such as extrusion straight lines are not allowed, and scale, glass lubricant particles and other impurities are not allowed, and phenomena such as under-acid, over-acid and rust spots are not allowed.
  • 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 uneven wall thickness does not exceed 80% of the wall thickness deviation.
  • the straightness of the extruded tube shall not exceed 2mm/m to meet the feed requirements for billet opening and cold rolling.
  • the extruded tube billet is prepared by multi-pass two-roll high-speed cold rolling, the deformation of the intermediate product is set at 50% ⁇ 80%, the feeding amount is controlled at 1 ⁇ 4mm/time, and the rolling mill speed is controlled at 60 ⁇ 200 times/min.
  • the inner and outer surfaces of the intermediate round tube after rolling are clean, and there must be no defects such as cracks, folds, scratches, and pits that affect subsequent finishing rolling, and the roughness of the inner and outer surfaces Ra does not exceed 1.60um.
  • the unevenness of the wall thickness of the middle round pipe does not exceed 5% of the wall thickness, which lays a solid foundation for the subsequent finish rolling of the outer hexagonal inner circle seamless pipe to meet the qualified profile index.
  • the temperature range of the intermediate heat treatment process for each pass is 1050 ° C ⁇ 1150 ° C, so that the intermediate product round tube can be well shaped, and the elongation after breaking is controlled at more than 40%, which is convenient for the subsequent final forming, and the full solid solution makes the tube
  • the grains are fully broken, and the grain size is controlled at 4.0 ⁇ 8.0, which is convenient for the flexible customization of the subsequent heat treatment process, and obtains excellent microstructure and performance.
  • the deformation process is the key step of this application.
  • various dimensional indicators are strictly controlled, and the intermediate product round tube is finally formed into a high-precision outer hexagonal and inner circular unequal-shaped cross-section by using three-roll finish rolling. seam pipe.
  • the amount of deformation required is relatively large. If the amount of deformation is too small, the metal flow in the inner circle will not be sufficient, and rolling will easily occur. Defects: If the deformation is too large, the rolling force required will be greater. Since the rolling force of the finishing mill is generally less, it will cause the pipe to be stuck and the inner surface of the pipe to be scratched. The reasonable final forming deformation is 30% ⁇ 80%.
  • the recommended cold rolling speed is 15 ⁇ 60 n/min, and the feed rate is 1.0 ⁇ 3.0mm/n.
  • the cold rolling method and the type of rolling mill are determined.
  • the three roll finish rolling machines of LD15, LD30 or LD60 are selected for rolling.
  • Solution heat treatment is also an important step for this application.
  • the wall thickness of the entire cross-section of the cold outer hexagonal inner tube is inconsistent.
  • Bright heat treatment or vacuum heat treatment can be used for solidification. dissolve. Specifically, bright heat treatment can be used, and vertical vacuum heat treatment can also be used.
  • the inert protective gas is selected as hydrogen with a purity greater than 99.95% to ensure that the finished pipe has good mechanical properties, and the internal and external surfaces of the pipe do not oxidize and discolor, ensuring that the pipe has a good surface quality.
  • the annealing temperature is 980-1100°C
  • the holding time is determined according to the wall thickness of the pipe. Usually, the holding time should be ensured to be the maximum wall thickness of the pipe * (1.0-6.0) min/mm, and it should be selected according to the mechanical performance index required by the finished product (1.0-6.0) value, the higher the required strength of the finished product, the finer the grain structure, the lower the selected value, and the cooling method adopts rapid air cooling.
  • the vacuum annealing temperature is 980°C-1100°C
  • the holding time is the maximum wall thickness of the pipe * (1.0-6.0) min/mm
  • the cooling method is quick cooling with argon filling to ensure uniform grain structure of the pipe;
  • the vacuum degree is not lower than 10-2Pa to prevent the surface from being oxidized and discolored;
  • the vertical hanging loading method is adopted, and the ends of the pipe are fixed on the tooling with stainless steel wires. Due to the influence of gravity, the bending deformation of the pipe can be reduced. Facilitate subsequent finishing treatment.
  • the straightening machine is used to finish and clean the heat-treated pipes to ensure that the external dimensions, surface quality and cleanliness meet the technical requirements.
  • Figure 1 is a schematic diagram of a high-precision outer hexagonal inner circle special-shaped cross-section seamless pipe for nuclear power.
  • the specific preparation method is as follows. High-precision hexagonal tubes of other specifications can be implemented with reference to this method, and the specific cold rolling, solution treatment, and straightening processes can be adaptively adjusted within the scope of this patent.
  • Step 01 Select 316H stainless steel rods, whose chemical composition should meet the corresponding provisions in GB/T 20878-2007 "Stainless Steel and Heat-resistant Steel Grades and Chemical Composition".
  • the rod ⁇ 204mm is made into a tube blank ⁇ 78mm by hot extrusion process, the extrusion temperature is about 1150°C ⁇ 1200°C, and the extrusion speed is 150mm/s.
  • Extruded pipes need to be straightened, cut, pickled and other finishing treatments, and the finished waste pipes should be inspected and ground one by one; the surface should be free of cracks, burrs, folds, shrinkage cavities, and scars And unacceptable defects such as scratches, folds, pressure pits, extrusion straights, etc., and no scale, glass lubricant particles and other impurities are allowed, and phenomena such as under-acid, over-acid and rust spots are not allowed.
  • the inner and outer surfaces of the intermediate product round tube must be clean and bright, and there must be no cracks, folds, scratches, pits and other defects that affect subsequent cold drawing.
  • the inner and outer surface roughness Ra of the intermediate product round tube is not more than 0.80um.
  • Step 1 The intermediate product round tube is formed from the tube billet through two passes of high-speed cold rolling.
  • the high-speed cold rolling deformation is set at 50-70%
  • the intermediate heat treatment process is set at 1050 ° C ⁇ 1100 ° C
  • the yield strength of the tube is controlled.
  • the elongation after breaking is greater than 50%, which is convenient for subsequent finishing rolling.
  • D0 is taken as 29mm according to the actual situation, and the tolerance is controlled at ⁇ 0.1mm.
  • the tolerance is controlled at ⁇ 0.05mm.
  • the uneven wall thickness is controlled within 0.05mm; the relative cold rolling deformation is about 40%; the length of the intermediate round tube is about 800mm.
  • Step 2 Perform heat treatment on the cold intermediate tube of each pass to adjust the mechanical properties of the intermediate tube.
  • the temperature range of the intermediate heat treatment process for each pass is 1100 ° C, so that the intermediate product round tube can be well shaped, and the elongation rate after breaking is controlled at more than 40%, and the full solid solution can fully break the grains of the tubes, and the grain size
  • the grade is controlled at 7.0.
  • Step 3 The intermediate product round pipe ⁇ 29 ⁇ 2.8mm is finally cold-formed by a finish rolling process to form a seamless pipe with an outer hexagonal inner circle with a distance across sides of 24mm and an inner diameter of 21.6mm.
  • the tools and dies are assembled on the rolling mill, and then the rolling of the hexagonal tube is carried out.
  • the inner and outer surfaces should be fully lubricated with rolling oil. Due to the relatively large amount of deformation, the cold rolling speed should not be too fast, and the feeding amount should not be too large, which will easily cause scratches on the pipe, so as not to affect the surface quality of the final product.
  • Recommended Cold rolling speed is 30 n/min, feed rate 1.5 mm/n.
  • the rolled pipes should be degreased and cleaned in time to ensure that the inner and outer surfaces are clean.
  • Step 4 The heat treatment of the finished product is carried out in a protective atmosphere bright annealing furnace for solution treatment, the set temperature is 1050°C, the holding time is 3min, the protective atmosphere is hydrogen, the purity is greater than 99.95%, and the dew point of the gas source is ⁇ -50°C.
  • the solid solution is sufficient, the structure is uniform, and the grain size is controlled at 7.0 ⁇ 8.0. To ensure that the finished pipe has high mechanical properties, and the internal and external surfaces of the pipe do not undergo oxidation and discoloration, and ensure that the pipe has a good surface quality. After the heat treatment, the pipe is finished.
  • Step 5 Check the surface quality, structure, and size of the finished hexagonal tubes one by one. The results are as follows:
  • the inner and outer surface roughness of the finished product is Ra ⁇ 0.8 ⁇ m.
  • the grain size is required to be 7 grades or finer, and the uniform grain grade difference of each part is not more than 1 grade.
  • the tensile test at 650°C high temperature requires tensile strength Rm ⁇ 332MPa, yield strength RP0.2 ⁇ 108MPa, and elongation of section A ⁇ 30%.

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Abstract

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。

Description

一种核电用高精度外六角内圆异形截面无缝管及其制造方法 技术领域
本发明涉及一种核电用高精度外六角内圆异形截面无缝管及其制造方法，属于新材料中的特种合金异形截面无缝管制备技术领域。
 背景技术
传统的外六角内圆无缝管制造工艺采用多道次冷轧加多道次的冷拔成形，或者采用热加工工艺定形加多道次的冷拔确定尺寸的工艺，这些工艺方案工艺道次多、生产效率低、生产的产品尺寸精度低，满足不了高精度外六边形、内圆形管的生产需求。
现有技术中，公开号为CN112692065A的专利申请公开了一种高强度薄壁不锈钢六边形无缝管及其制造方法，该六边形无缝管由管坯原料经多道次冷轧或冷拔变形及热处理后，再分两步多辊精密冷轧成型，成型后该六边形无缝管各处的横截面积呈封闭的正六边形，其中壁厚为1.0mm-3.5mm，内对边距40m-120mm，成型后六边形无缝管表面粗糙度≤0.8μm，壁厚公差±0.05mm，内对边距公差±0.10mm，具有高表面光洁度和高尺寸精度特征，本发明制备出中间品圆管规格灵活可变、成品异型管高表面光洁度、高尺寸精度、高强度兼顾的高强度薄壁不锈钢六边形无缝管。
限于大口径的内外都是六边形的等壁厚无缝管制造技术，该申请专利技术对于本专利技术提到的高精度外六角、内圆形不锈钢无缝管的制造，存在以下问题：该现有技术公开的制造方法限于制造大口径六边形管，小口径六边形管材的尺寸及尺寸精度控制则无法使用该方法实施；该现有技术公开的无缝管从圆管变形到六边形管，同一截面上壁厚都是相等的，变形量≤15%就能成型，而对于不等壁六边管的制造变形量需求大，变形量太少，变形不充分会影响最后产品的尺寸和精度；另外，该无缝管最终成品是冷态未进行热处理，对于一些用于高温环境下的六边形管，管材会发生变形，从而影响尺寸精度。
 技术解决方案
本发明要解决的技术问题是提供一种核电用高精度外六角内圆异形截面无缝管及其制造方法，
本发明是通过以下技术方案来实现的。
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。
作为本发明的进一步改进，其表面粗糙度Ra≤0.8μm。
本申请的外六角内圆管尺寸更小、尺寸精度要求更高、尺寸参数要求更多，在装配的时候更加轻松，并增大了管材的适用范围；同时成品在后述的制造方法中采用固溶热处理，管材的延伸率＞35%，使管材具有优异的综合力学性能，适用于高温环境下使用。
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，其特征在于，步骤包括：
步骤01：采用热挤压工艺将棒材制成管坯；
步骤1：将管坯经过多道次的二辊高速冷轧，制成中间品圆管；
步骤2：对每个道次冷态的中间品圆管进行热处理，调整中间品圆管的力学性能；
步骤3：采用三辊精轧完成中间品圆管到外六角内圆异形截面无缝管的变形过程；
步骤4：对冷态的外六角内圆异形截面无缝管先进行固溶热处理，后进行冷却处理；
步骤5：采用矫直机，对外六角内圆异形截面无缝管进行矫形处理。
步骤6：清洁处理和成品检验。
本申请的制造方法中，步骤3将中间品圆管变形为外六角内圆异形截面无缝管的变形工艺是核心步骤，而实施该步骤的基础和关键点是根据成品规格来定义中间品圆管的的个尺寸指标。
其中，中间品圆管的外径D0（mm）设计要求：为保证管材的外六角成形，中间品圆管的周长L0（mm）要大于成型后的外六角内圆异形截面无缝管即成型管的周长L1（mm），
即：L0=μL1
π*D0=μ*2√3*D1 →
D0=1.1μ*D1
式中：μ为变形常数，可取1.0~1.5；具体根据变形量以及中间品圆管外径成型方便性进行选取，在满足轧机能力的条件下，要求的变形量越大，μ选取的数值越大。
D0为来中间品圆管的外径，单位为mm；
D1为成型管的对边距，单位为mm。
中间品圆管的壁厚S0（mm）设计要求：为保证管材充分变形，内圆填充完整无凹槽，中间品圆管的壁厚要大于成型管的最大壁厚S1max（mm）。
即：S0＞S1max =D1/√3-d1/2 -ΔS1，ΔS1=0.1r。
式中：S0为中间品圆管的壁厚，单位为mm；
S1max为成型管的最大壁厚，单位为mm；
D1为成型管的对边距，单位为mm；
d1为成型管的内径，单位为mm；
ΔS1是由于R角的存在，成型管的最大壁厚与实际尺寸的偏小值，单位为mm；R角为成型管外六角形的6个呈圆弧过渡的夹角；
r为成型管的夹角圆弧（简称R角）的半径值，单位为mm；
由于满足六角管一次冷轧成形的变形量很大、比较困难，所以中间品圆管的规格选择在满足基本的轧制变形能力之下，S0尽量取下限值。
为保证管材成形时的均匀性，成形后的直线度、扭转度的要求，中间品圆管的壁厚不均需保证不超过壁厚的5%。
对于步骤01：
根据最终成型的工艺参数设计确定的中间品圆管规格确定棒材的规格尺寸、挤压管坯的规格、以及中间品冷轧的工艺，管坯采用棒材热挤压而成，挤压温度为1100℃到1250℃、挤压速度为100~200mm/s。挤压过后，管坯需进行矫直、切管、酸洗等精整处理。
对精整后的荒管逐支进行检验与修磨处理，精整后的挤压管表面应无裂纹、毛刺、折迭、缩孔、结疤以及不可接受的划伤、折叠、压坑、挤压直道等缺陷，且不允许有氧化皮、玻璃润滑剂颗粒及其他杂质，不允许存在欠酸、过酸和锈斑等现象。精整后的挤压管外径偏差为外径的±1%，壁厚偏差为壁厚的±10%，壁厚不均不超过壁厚偏差的80%。挤压管直线度不超过2mm/m，以满足开坯冷轧进料要求。
对于步骤1：
挤压后的管坯经过多道次的两辊高速冷轧制备，中间品两辊冷轧的变形量设置50%~80%，送进量控制在1~4mm/次，轧机速度控制在60~200次/min。
轧制后的中间圆管的内外表面洁净，不得有裂纹、折叠、划伤、凹坑等影响后续精轧的缺陷存在，内外表面粗糙度Ra不超过1.60um。中间圆管的壁厚不均不超过壁厚的5%，为后续精轧出外六角内圆无缝管的轮廓度指标能合格打下了坚实的基础。
对于步骤2：
每个道次中间热处理工艺温度范围为1050℃～1150℃，使中间品圆管获得了良好的塑形，断后伸长率控制在40%以上，便于后续的最终成型，充分固溶使管材的晶粒充分地破碎，晶粒度等级控制在4.0~8.0级，便于后续的热处理工艺灵活定制，获得优良的组织和性能。
对于步骤3：
变形工艺是本申请的关键步骤，通过最终成型工艺参数设计严控各个尺寸指标，采用三辊精轧将中间品圆管最终成型为高精度外六角形、内圆形不等壁的异形截面无缝管。
由于采用三辊精轧一次直接由圆管成型到外六角形、内圆形管，所需要的变形量相对较大，如果变形量过小，会导致内圆金属流动不充分，容易产生轧制缺陷；变形量过大，所需要轧制力就越大，由于精轧机的轧制力一般较少，会导致管材卡顿，造成内表管材擦伤，合理的最终成型变形量为30%~80%。推荐的冷轧速度为15~60 n/min，送进量为1.0~3.0mm/n。根据参数设计出合适的工模具，同时控制外对边距、内圆直径、R角、平面中心点最小壁厚、R角处最大壁厚、棱边直线度、扭转度、面轮廓度、管端垂直度等尺寸，确保满足技术要求；轧制后的管材应及时脱脂清洗，确保内外表面洁净。
根据中间品圆管的要求以及变形量的选取，确定冷轧的方式和轧机的类型，一般选取LD15或LD30或LD60该三种辊精轧机型进行轧制。
对于步骤4：
固溶热处理也是本申请的重要步骤。冷态外六角内圆管的整个横截面壁厚不一致，在要确保在相同的热处理条件下，不同壁厚处的组织均匀一致，对热处理的定制要求高，可采用光亮热处理或真空热处理进行固溶。具体的，可采用光亮热处理，也可采用立式真空热处理。
如采用光亮热处理，则惰性保护气体选用为纯度大于99.95%的氢气，确保成品管材具有较好的力学性能，且管材内外表面不发生氧化变色现象，保证管材具有较好的表面质量。退火温度980-1100℃，保温时间根据管材壁厚确定，通常应确保保温时间为管材最大壁厚*(1.0—6.0)min/mm，根据成品需要的力学性能指标确定（1.0—6.0）选取值，成品所需强度越高，晶粒组织越细，选取值越低，冷却方式采用快速风冷。
如采用立式真空热处理，真空退火温度为980℃-1100℃，保温时间为管材最大壁厚*(1.0—6.0)min/mm，冷却方式采用充氩气快冷，保证管材晶粒组织均匀；加热过程中真空度不低于10-2Pa，以防止表面氧化变色；采用垂直悬挂的装料方式，管材头尾两端使用不锈钢丝固定在工装上，由于重力的影响，可以减少管材弯曲变形，便于后续的精整处理。
对于步骤5：
采用矫直机对热处理后管材进行精整处理和清洁处理，确保外形尺寸、表面质量和清洁度符合技术要求。
 有益效果
（1）提出一种先进的尺寸计算公式，便于确定规格范围和尺寸控制；
（2）优化设计合理工艺，满足外六角形、内圆形不锈钢无缝管冷加工成型要求；
（3）冷轧过程中同时控制外对边距、内圆直径、R角、平面中心点最小壁厚、R角处最大壁厚、棱边直线度、扭转度、面轮廓度、管端垂直度等尺寸参数，确保满足技术要求；
（4）设计合理固溶热处理工艺参数，确保产品性能满足技术要求。
 附图说明
下面将通过附图详细描述本发明中优选实施案例，以助于理解本发明的目的和优点，其中：
图1为核电用高精度外六角内圆异形截面无缝管的示意图。
 本发明的实施方式
下面根据附图和实施案例对本发明作进一步详细说明。
在本说明书中提到或者可能提到的上、下、左、右、前、后、正面、背面、顶部、底部等方位用语是相对于各附图中所示的构造进行定义的，词语“内”和“外”分别指的是朝向或远离特定部件几何中心的方向它们是相对的概念，因此有可能会根据其所处不同位置、不同使用状态而进行相应地变化。所以，也不应当将这些或者其他的方位用语解释为限制性用语。
如图1所示，核电用高精度外六角内圆异形截面无缝管，外对边距D1=24.0mm、偏差±0.05mm；内圆直径d1=21.6mm、偏差±0.05mm；最小壁厚S1min=1.15mm、长度L3=1000mm、面轮廓度0.05mm，六角管外角的角半径值R≤3mm。针对该典型目标产品，具体实施的制备方法如下文所述。其他规格高精度六角管可参考本方式实施，具体冷轧、固溶处理、矫直工艺可在本专利范围内作适应性调整。
步骤01：选取316H不锈钢材质的棒材，其化学成分应符合GB/T 20878-2007 《不锈钢和耐热钢 牌号和化学成分》标准中相应规定。采用热挤压工艺将棒材φ204mm制成管坯φ78mm，其中挤压温度为1150℃~1200℃左右，挤压速度在150mm/s。
挤压后的管材需进行矫直、切管、酸洗等精整处理，对精整后的荒管逐支进行检验与修磨；表面应无裂纹、毛刺、折迭、缩孔、结疤以及不可接受的划伤、折叠、压坑、挤压直道等缺陷，且不允许有氧化皮、玻璃润滑剂颗粒及其他杂质，不允许存在欠酸、过酸和锈斑等现象。中间品圆管的内外表面需洁净、光亮，不得有裂纹、折叠、划伤、凹坑等影响后续冷拔的缺陷存在。中间品圆管内外表面粗糙度Ra不超过0.80um。
步骤1：由管坯经过两个道次的高速冷轧而成中间品圆管，高速冷轧变形量设置为50~70%，中间热处理工艺设置在1050℃~1100℃,管材的屈服强度控制在250MPa~300MPa，断后伸长率大于50%，便于后续的精轧成型。
中间品圆管的外径：D0=1.1μ*D1，变形常数μ取1.1，即D0=29.04mm。为了便于尺寸控制，根据实际情况D0取29mm，公差控制在±0.1mm。中间品圆管的壁厚：S0＞S1max =D1/√3-d1/2 -ΔS1，ΔS1=0.1R，即S0＞2.75mm。为了便于尺寸控制，根据实际情况S0=2.8mm，公差控制在±0.05mm。壁厚不均控制在0.05mm以内；相对冷轧变形量在40%左右；中间品圆管长度为800mm左右。
步骤2：对每个道次冷态的中间品圆管进行热处理，调整中间品圆管的力学性能。每个道次中间热处理工艺温度范围为1100℃，使中间品圆管获得了良好的塑形，断后伸长率控制在40%以上，充分固溶使管材的晶粒充分地破碎，晶粒度等级控制在7.0级。
步骤3：中间品圆管φ29×2.8mm采用精轧工艺进行最终冷加工成形为对边距为24mm、内径为21.6mm的外六边形内圆形的无缝管。通过冷变形工艺设计，确定轧制所需要工模具：轧辊、顶头、滑道等。将工模具装配在轧机上，然后进行六角管的轧制。冷轧过程，内外表要采用轧制油充分润滑，由于变形量比较大，冷轧速度不宜过快，送进量不宜过大，容易造成管材擦伤，以免影响最终成品的表面质量，推荐的冷轧速度为30 n/min，送进量1.5 mm/n。轧制后的管材应及时脱脂清洗，确保内外表面洁净。
步骤4：成品热处理采用保护气氛光亮退火炉进行固溶处理，设定温度1050℃，保温时间3min，保护气氛为氢气，纯度大于99.95%，气源露点≤－50℃。成品管材热处理过程中固溶充分，组织均匀，晶粒度控制在7.0~8.0级。确保成品管材具有较高的力学性能，且管材内外表面不发生氧化变色现象，保证管材具有较好的表面质量。对热处理后管材进行精整处理。
步骤5：对定尺后的成品六角管逐支进行表面质量、组织、尺寸检测，结果如下：
1)    表面质量
技术要求：
管材表面不得有氧化色、油、或其它润滑剂、金属碎片或其它异物、裂纹、凹坑、氧化膜、砂眼或不利于管材使用的其他缺陷；
成品的内外表面粗糙度Ra≤0.8μm。
检测结果：表面粗糙度Ra=0.4μm，表面质量符合技术条件要求。
2)    组织和性能
技术要求：
晶粒度要求7级或更细，各部位组织均匀晶粒级别差不超过1级，650℃高温拉伸试验要求抗拉强度Rm≥332MPa、屈服强度RP0.2≥108MPa、断面伸长率A≥30%。
检测结果：
晶粒度为8.0级~8.5级；室温拉伸试验的抗拉强度Rm=610MPa、屈服强度RP0.2=300 MPa、断面伸长率A=58.0%；650℃高温拉伸试验的抗拉强度Rm=372MPa、屈服强度RP0.2=137MPa、断面伸长率A=48.0%。均满足技术条件要求。
3)    尺寸
技术要求：
对边距：24±0.05mm；内径偏差：21.6±0.05mm；最小壁厚≥1.15mm；面轮廓度≤0.05mm，端口垂直度为≤0.05mm，外角的角半径值≤3mm，长度为1000±0.5mm。
检测结果:
对边距=24.05~23.97mm；最小壁厚=1.20~1.26mm；内径=21.65～21.56mm；长度=1000.5mm；面轮廓度=0.05mm；端口垂直度=0.03mm；六角管外角的角半径值R=3mm。均满足技术条件要求。
最后应说明的是：以上实施案例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述实施案例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施案例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本发明各实施案例技术方案的范围。

Claims (12)

  1. 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。
  2. 根据权利要求1所述的核电用高精度外六角内圆异形截面无缝管，其特征在于，其表面粗糙度Ra≤0.8μm。
  3. 一种如权利要求1或2所述的核电用高精度外六角内圆异形截面无缝管的制造方法，其特征在于，步骤包括：
    步骤1：将管坯经过多道次的二辊高速冷轧，制成中间品圆管；
    D0=1.1μ*D1；
    D0为中间品圆管的外径，D1为成型后的外六角内圆异形截面无缝管即成型管的对边距，μ为1.0~1.5；
    S0＞S1max =D1/√3-d1/2 -ΔS1，ΔS1=0.1r；
    S0为中间品圆管的壁厚，S1max为成型管的最大壁厚，D1为成型管的对边距，d1为成型管的内径，r为成型管的夹角圆弧的半径值；
    步骤2：对每个道次冷态的中间品圆管进行热处理，调整中间品圆管的力学性能；
    步骤3：采用三辊精轧完成中间品圆管到外六角内圆异形截面无缝管的变形过程；
    步骤4：对冷态的外六角内圆异形截面无缝管先进行固溶热处理，后进行冷却处理。
  4. 根据权利要求3所述的核电用高精度外六角内圆异形截面无缝管的制造方法，其特征在于，所述步骤1中，二辊高速冷轧的变形量为50%~80%，送进量控制在1~4mm/次，轧机速度控制在60~200次/min。
  5. 根据权利要求3所述的核电用高精度外六角内圆异形截面无缝管的制造方法，其特征在于，所述步骤2中，每个道次冷态的中间品圆管热处理的温度为1050℃～1150℃，晶粒度等级控制在4.0~8.0级。
  6. 根据权利要求3所述的核电用高精度外六角内圆异形截面无缝管的制造方法，其特征在于，所述步骤3中，三辊精轧变形过程的变形量为30%~80%，冷轧速度为15~60 n/min，送进量为1.0~3.0mm/n。
  7. 根据权利要求6所述的核电用高精度外六角内圆异形截面无缝管的制造方法，其特征在于，所述步骤3的三辊精轧选用LD15或LD30或LD60型号的三辊精轧机。
  8. 根据权利要求3所述的核电用高精度外六角内圆异形截面无缝管的制造方法，其特征在于，所述步骤4的固溶热处理为用光亮热处理；使用纯度大于99.95%的氢气作为惰性气体保护，退火温度在980-1100℃，保温时间为成型管的最大壁厚*(1.0—6.0)min/mm；冷却处理采用快速风冷。
  9. 根据权利要求3所述的核电用高精度外六角内圆异形截面无缝管的制造方法，其特征在于，所述步骤4的固溶热处理为立式真空热处理；真空退火温度为980℃-1100℃，保温时间为管材最大壁厚*(1.0—6.0)min/mm；冷却处理采用充氩气快冷。
  10. 根据权利要求3所述的核电用高精度外六角内圆异形截面无缝管的制造方法，其特征在于，还包括步骤5：采用矫直机，对外六角内圆异形截面无缝管进行矫形处理。
  11. 根据权利要求3所述的核电用高精度外六角内圆异形截面无缝管的制造方法，其特征在于，所述步骤1之前还包括步骤01：采用热挤压工艺将棒材制成管坯。
  12. 根据权利要求11所述的核电用高精度外六角内圆异形截面无缝管的制造方法，其特征在于，所述步骤01中，热挤压工艺的挤压温度为1100℃到1250℃、挤压速度为100~200mm/s。
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