CN110760753B - Low-yield-ratio seamless steel pipe and manufacturing method thereof - Google Patents
Low-yield-ratio seamless steel pipe and manufacturing method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 104
- 239000010959 steel Substances 0.000 title claims abstract description 104
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 21
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 10
- 239000002131 composite material Substances 0.000 claims abstract description 7
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 6
- 239000000126 substance Substances 0.000 claims abstract description 6
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 5
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 5
- 229910001563 bainite Inorganic materials 0.000 claims abstract description 4
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 4
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 4
- 238000001816 cooling Methods 0.000 claims description 21
- 238000010438 heat treatment Methods 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 15
- 238000004321 preservation Methods 0.000 claims description 9
- 238000005266 casting Methods 0.000 claims description 4
- 230000035515 penetration Effects 0.000 claims description 4
- 238000007670 refining Methods 0.000 claims description 4
- 238000007493 shaping process Methods 0.000 claims description 4
- 238000009628 steelmaking Methods 0.000 claims description 4
- 239000011572 manganese Substances 0.000 description 9
- 229910001566 austenite Inorganic materials 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 239000003921 oil Substances 0.000 description 5
- 239000010936 titanium Substances 0.000 description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- 238000005204 segregation Methods 0.000 description 4
- 229910052719 titanium Inorganic materials 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 238000004513 sizing Methods 0.000 description 3
- 238000009785 tube rolling Methods 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 229910000885 Dual-phase steel Inorganic materials 0.000 description 1
- 229910000954 Medium-carbon steel Inorganic materials 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
The invention relates to a seamless steel tube with low yield ratio and a manufacturing method thereof, wherein the seamless steel tube comprises the following chemical components in percentage by mass: 0.30 to 0.40 percent of C, 0.25 to 0.5 percent of Si, 0.4 to 0.7 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.020 percent of S, 0.035 to 0.055 percent of Ti, RE: 0.05 to 0.18 percent, and the balance of Fe and inevitable impurities. The tissue characteristics are as follows: the tissue is B + F or B + F + M composite tissue; wherein B is lath bainite, F is massive, granular or lath ferrite, and M is martensite. The yield ratio of the seamless steel tube produced by the invention can reach below 0.85, the yield strength reaches the steel grade level above 650MPa, and the seamless steel tube can better meet the requirements of industries such as oil gas exploitation and the like on the tube.
Description
Technical Field
The invention relates to the technical field of seamless steel pipe production, in particular to a seamless steel pipe with a low yield ratio and a manufacturing method thereof.
Background
With the development of materials used in the fields of engineering machinery, construction, containers, oil and gas exploitation and the like towards high strength, the safety of the materials is more and more concerned. The yield ratio reflects the cold deformability and plastic deformability of the steel. Achieving a low yield ratio of the material has been a constant goal pursued in the industry in view of the safety of the components.
In terms of industrial design of steel for oil and gas exploitation, it has been successful to achieve a yield ratio of less than 0.85 for seamless pipes with a steel yield strength of 550MPa or less. For example, the yield ratio of a steel pipe manufactured by a K55 steel-grade petroleum casing pipe disclosed in Chinese patent with the application number of CN200710093884 can be less than 0.85, but the disadvantage is that the upper limit of the yield strength is only 552 MPa. However, the mainstream strength steel grade of the current oil and gas exploitation is upgraded from 55ksi steel grade to 80ksi steel grade or even higher, so the technical scheme of the invention can not meet the use requirement of the oil and gas exploitation project to the seamless steel pipe with low yield ratio in the present and future, and the application range of the product is severely limited.
Chinese patent application No. CN201010221546 discloses an X70QS steel grade seamless steel tube, which meets technical indexes by adding a large amount of alloy element types and amounts, but only achieves a yield ratio of not more than 0.9, the upper limit of yield strength cannot break 635MPa, the use safety is not high, and the application range is limited;
chinese patent No. CN201410175317 discloses a high-strength plastic vanadium microalloyed dual-phase steel seamless tube, but since the low yield ratio is obtained by mainly applying the TRIP effect principle, it is bound to take the premise of greatly sacrificing the yield strength of the material, so that the upper limit of the yield strength of the product cannot exceed 635 MPa. The yield strength of the produced seamless steel pipe with low yield ratio is less than 635 MPa.
In conclusion, the technical difficulty of producing seamless steel tubes with yield strength of above 650MPa and low yield ratio is not broken through, belongs to the current technical blank of the seamless steel tube industry, and is a technical problem which needs to be solved urgently in the actual production of the current enterprises.
Disclosure of Invention
The invention provides a low-yield-ratio seamless steel tube and a manufacturing method thereof, wherein the yield ratio can reach below 0.85, the yield strength reaches the steel grade level above 650MPa, and the low-yield-ratio seamless steel tube can meet the current and future requirements on tubes in the industries such as oil and gas exploitation and the like.
In order to achieve the purpose, the invention adopts the following technical scheme:
a low yield ratio seamless steel pipe comprises the following chemical components in percentage by mass: 0.30 to 0.40 percent of C, 0.25 to 0.5 percent of Si, 0.4 to 0.7 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.020 percent of S, 0.035 to 0.055 percent of Ti, RE: 0.05 to 0.18 percent, and the balance of Fe and inevitable impurities.
The seamless steel pipe has the following performance characteristics:
1) the minimum yield strength Rt0.5 reaches above 650 Mpa;
2) the minimum tensile strength Rm reaches above 785 MPa;
3) the maximum yield ratio is not more than 0.85;
4) the minimum elongation A after fracture is not less than 18 percent;
5) the minimum value of the impact energy of the V-shaped notch at 0 ℃ is not lower than 58J.
The seamless steel pipe has the structural characteristics that: the tissue is B + F or B + F + M composite tissue; wherein B is strip-shaped bainite, F is massive, granular or strip-shaped ferrite, M is martensite, and the proportion of B in the structure is not lower than 90%; when the structure of the seamless steel tube is a B + F + M composite structure, the proportion of F is 5-10%; the proportion of M is not higher than 5%.
A manufacturing method of a seamless steel pipe with low yield ratio comprises the working procedures of steel making, external refining, billet casting, round billet manufacturing, pipe penetration, high-temperature deformation heat treatment of the steel pipe, steel pipe shaping and steel pipe heat treatment; the temperature of the shaped seamless steel pipe is more than 750 ℃, and the heat treatment of the steel pipe comprises the following processes:
1) rapidly cooling the seamless steel tube to below 550 ℃, wherein the cooling speed is 3-9 ℃/s;
2) the cooled seamless steel tube is heated to 780 +/-10 ℃ again, and the heat preservation time is controlled according to 1-2 min/mm of wall thickness;
3) rapidly cooling the seamless steel tube to 200-400 ℃ again, wherein the cooling speed is not lower than 35-65 ℃/s; the heat preservation time is controlled according to 1-5 min/mm wall thickness;
4) straightening and deforming the seamless steel pipe;
5) and air cooling the straightened steel pipe to room temperature.
Compared with the prior art, the invention has the beneficial effects that:
1) the seamless steel tube manufactured by the material and the process has the performance characteristics that the yield ratio is less than or equal to 0.85 and the yield strength is more than or equal to 650MPa, and the safety of the high-strength seamless steel tube with the steel grade above K55 in the use environments such as oil-gas wells and the like can be greatly improved; compared with the existing seamless steel tube product with low yield ratio, the product has the advantages of high yield strength;
2) the seamless steel tube product has the characteristics of low chemical component composition cost and simple and compact process flow, can save a large amount of expensive metals such as V, Mo and the like compared with the technical scheme of obtaining low yield ratio by adding alloy, has the advantage of low manufacturing cost, and ensures that the product has market competitiveness;
3) the seamless steel pipe manufactured by the technical scheme of the invention has excellent comprehensive mechanical property, is beneficial to expanding the application of products in the fields of bridges, machinery, buildings and the like, and has wide market prospect.
Detailed Description
The invention relates to a seamless steel tube with low yield ratio, which comprises the following chemical components in percentage by mass: 0.30 to 0.40 percent of C, 0.25 to 0.5 percent of Si, 0.4 to 0.7 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.020 percent of S, 0.035 to 0.055 percent of Ti, RE: 0.05 to 0.18 percent, and the balance of Fe and inevitable impurities.
The seamless steel pipe has the following performance characteristics:
1) the minimum yield strength Rt0.5 reaches above 650 Mpa;
2) the minimum tensile strength Rm reaches above 785 MPa;
3) the maximum yield ratio is not more than 0.85;
4) the minimum elongation A after fracture is not less than 18 percent;
5) the minimum value of the impact energy of the V-shaped notch at 0 ℃ is not lower than 58J.
The seamless steel pipe has the structural characteristics that: the tissue is B + F or B + F + M composite tissue; wherein B is strip-shaped bainite, F is massive, granular or strip-shaped ferrite, M is martensite, and the proportion of B in the structure is not lower than 90%; when the structure of the seamless steel tube is a B + F + M composite structure, the proportion of F is 5-10%; the proportion of M is not higher than 5%.
A manufacturing method of a seamless steel pipe with low yield ratio comprises the working procedures of steel making, external refining, billet casting, round billet manufacturing, pipe penetration, high-temperature deformation heat treatment of the steel pipe, steel pipe shaping and steel pipe heat treatment; the temperature of the shaped seamless steel pipe is more than 750 ℃, and the heat treatment of the steel pipe comprises the following processes:
1) rapidly cooling the seamless steel tube to below 550 ℃, wherein the cooling speed is 3-9 ℃/s;
2) the cooled seamless steel tube is heated to 780 +/-10 ℃ again, and the heat preservation time is controlled according to 1-2 min/mm of wall thickness;
3) rapidly cooling the seamless steel tube to 200-400 ℃ again, wherein the cooling speed is not lower than 35-65 ℃/s; the heat preservation time is controlled according to 1-5 min/mm wall thickness;
4) straightening and deforming the seamless steel pipe;
5) and air cooling the straightened steel pipe to room temperature.
The design principle of the alloy elements and the content range in the seamless steel pipe is as follows:
c: the carbon has the main functions of solid solution strengthening, improving hardenability and improving the stability of the undercooled austenite in the cooling process. When the carbon content is less than 0.30%, the stability and strength of the supercooled austenite of the steel are difficult to ensure, and the object of the present invention cannot be achieved. And too high carbon element can seriously limit the cooling speed of steel, difficult to obtain expected structure proportion, easy to generate product cracking and difficult to achieve the aim of the invention. In addition, since an excessively high C content increases hydrogen embrittlement sensitivity and increases production cost and lowers production efficiency in order to cope with this problem, the upper limit of the carbon content in the present invention is defined to be not higher than 0.40%.
Si: in the present invention, silicon mainly plays a role of solid solution strengthening and deoxidation, but is limited to 0.5% or less because it greatly impairs the toughness of steel.
Mn: manganese can improve hardenability and the stability of the undercooled austenite in the cooling process. The Mn can be combined with the S element in the steel to form MnS, so that the hot brittleness of the steel can be avoided, meanwhile, the Mn can expand the austenite area of the steel, the grain refinement is facilitated, the effect of improving the obdurability of the steel is achieved, the effect can not meet the requirement of the invention when the content is lower than 0.4 percent, and the effect of promoting the segregation of harmful elements in the grain boundary starts to be obvious when the content is higher than 0.7 percent, so that the performance uniformity of the seamless steel pipe is reduced. Therefore, the Mn content is limited to 0.4% to 0.7% in the present invention.
P: phosphorus segregation in grain boundaries increases the ductile-brittle transition temperature and reduces the toughness of the steel, and the content of phosphorus segregation in grain boundaries is limited to 0.025% or less.
S: sulfur is easy to form non-hard inclusions with manganese and the like, and the non-hard inclusions extend and deform along the rolling direction in the machining process, so that the continuity of a material matrix is damaged, and the toughness index of a V-shaped notch of the seamless steel pipe in summer ratio is reduced. The content of the organic solvent is limited to 0.020% or less.
Ti: the affinity of titanium and nitrogen is very strong, free nitrogen in steel can be fixed, the hydrogen induced cracking tendency of medium-carbon steel is improved, meanwhile, carbon and nitride formed by titanium, carbon and nitrogen can play a role in delaying austenite grain growth and improving toughness, but the effect is not obvious when the content of titanium is higher than 0.055%, and smelting cost is greatly increased, so that the content range of titanium is limited to 0.035-0.055% in the invention.
RE: the invention can inhibit carbide which is continuously distributed along the prior austenite grain boundary from precipitating and improving the toughness of the steel by segregation at the austenite grain boundary, the addition amount is generally more than 0.05 percent, and the content range of RE is controlled to be 0.05 to 0.18 percent according to the content of Mn.
The following examples are carried out on the premise of the technical scheme of the invention, and detailed embodiments and specific operation processes are given, but the scope of the invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.
[ examples ] A method for producing a compound
In this embodiment, the production process of the seamless steel tube with low yield ratio includes the following steps: steel making, external refining, billet casting, round billet manufacturing, pipe penetration, high-temperature deformation heat treatment of steel pipes, steel pipe shaping and steel pipe heat treatment.
In this example, the chemical composition of the seamless steel pipe is shown in table 1;
TABLE 1
The molten steel is cast and forged to form a pipe blank with the diameter of 185 x 10050 mm. Cutting the tube blank into required fixed length, feeding the tube blank into a heating furnace for heating, then sequentially passing through a tube penetrating machine, a tube rolling machine and a sizing machine for sizing, performing heat treatment, straightening and flaw detection, and finally obtaining a seamless tube finished product. Wherein the heating temperature of the round billet in the heating furnace is 1250-1280 ℃, the perforating temperature of the perforating machine is 1200-1250 ℃, the tube rolling temperature of the tube rolling machine is 1100-1200 ℃, and the sizing temperature is more than 750 ℃.
In this embodiment, the heat treatment process of the steel pipe as the core technology of the present invention is performed as follows:
1) rapidly cooling the shaped seamless steel pipe to below 550 ℃;
2) the seamless steel pipe cooled in the step 1) enters a first heat treatment furnace in an online mode preferentially to be heated to 780 +/-10 ℃, and the heat preservation time is controlled according to 1-2 min/mm;
3) rapidly cooling the seamless steel pipe heated in the step 2) to 200-400 ℃ again, and entering a second heat treatment furnace for heat preservation, wherein the heat preservation time is controlled according to 1-5 min/mm;
4) straightening the seamless steel pipe processed in the step 3) with temperature;
5) and air cooling the straightened seamless steel pipe to room temperature.
The process parameters of the above production process are shown in table 2.
TABLE 2
And finally, after various inspections such as flaw detection and pipe end processing, packaging and warehousing the seamless steel pipe.
The mechanical properties of the seamless steel tube with a diameter of 139.70X 9.17mm manufactured by the above process are shown in Table 3.
TABLE 3
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (1)
1. The manufacturing method of the seamless steel pipe with the low yield ratio is characterized in that the chemical components of the seamless steel pipe with the low yield ratio in percentage by mass are as follows: 0.30 to 0.40 percent of C, 0.25 to 0.5 percent of Si, 0.4 to 0.47 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.020 percent of S, 0.035 to 0.055 percent of Ti, RE: 0.05 to 0.18 percent, and the balance of Fe and inevitable impurities;
the seamless steel pipe has the following performance characteristics: 1) the yield strength Rt0.5 reaches above 650 Mpa; 2) the tensile strength Rm reaches more than 785 MPa; 3) the yield ratio is not more than 0.85; 4) the elongation A after fracture is not less than 18 percent; 5) the impact energy of the V-shaped notch is not lower than 58J at 0 ℃;
the seamless steel pipe has the structural characteristics that: the tissue is B + F or B + F + M composite tissue; wherein B is strip-shaped bainite, F is massive, granular or strip-shaped ferrite, M is martensite, and the proportion of B in the structure is not lower than 90%; when the structure of the seamless steel tube is a B + F + M composite structure, the proportion of F is 5-10%; the proportion of M is not higher than 5%;
the manufacturing method of the seamless steel pipe with low yield ratio comprises the working procedures of steel making, external refining, billet casting, round billet manufacturing, pipe penetration, high-temperature deformation heat treatment of the steel pipe, steel pipe shaping and steel pipe heat treatment; the method is characterized in that the temperature of the shaped seamless steel pipe is more than 750 ℃, and the heat treatment of the steel pipe comprises the following steps:
1) rapidly cooling the seamless steel tube to below 550 ℃, wherein the cooling speed is 3-9 ℃/s;
2) the cooled seamless steel tube is heated to 780 +/-10 ℃ again, and the heat preservation time is controlled according to 1-2 min/mm of wall thickness;
3) rapidly cooling the seamless steel tube to 200-400 ℃ again, wherein the cooling speed is not lower than 35-65 ℃/s; the heat preservation time is controlled according to 1-5 min/mm wall thickness;
4) straightening and deforming the seamless steel pipe;
5) and air cooling the straightened steel pipe to room temperature.
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| CN201911023043.0A CN110760753B (en) | 2019-10-25 | 2019-10-25 | Low-yield-ratio seamless steel pipe and manufacturing method thereof |
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| CN110760753B true CN110760753B (en) | 2021-04-27 |
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| JP4609138B2 (en) * | 2005-03-24 | 2011-01-12 | 住友金属工業株式会社 | Manufacturing method of oil well pipe steel excellent in sulfide stress cracking resistance and oil well seamless steel pipe |
| CN101658879A (en) * | 2008-08-27 | 2010-03-03 | 宝山钢铁股份有限公司 | Method for manufacturing seamless steel pipe |
| JP5324311B2 (en) * | 2009-05-15 | 2013-10-23 | 株式会社神戸製鋼所 | Hollow seamless pipe for high strength springs |
| JP5476597B2 (en) * | 2010-03-04 | 2014-04-23 | 株式会社神戸製鋼所 | Seamless steel pipe for high-strength hollow springs |
| CN102407245A (en) * | 2011-10-28 | 2012-04-11 | 东北大学 | Method for producing transformation induced plasticity (TRIP) seamless tube |
| CN102363833B (en) * | 2011-10-28 | 2013-06-05 | 东北大学 | Method for manufacturing transformation induced plasticity steel seamless tube on line |
| CN102699628B (en) * | 2012-03-26 | 2015-07-29 | 天津钢管集团股份有限公司 | Diameter is the production method of the pipeline with hydrogen sulfide corrosion resistance seamless steel pipe of 508mm |
| CN103276308A (en) * | 2013-05-09 | 2013-09-04 | 内蒙古包钢钢联股份有限公司 | Rare earth-containing high-strength atmospheric corrosion-resistant seamless steel pipe and production method thereof |
| CN103290334A (en) * | 2013-05-09 | 2013-09-11 | 内蒙古包钢钢联股份有限公司 | Atmosphere corrosion resistance seamless steel tube containing rare earth and production method thereof |
| CN103320699B (en) * | 2013-05-09 | 2015-09-16 | 内蒙古包钢钢联股份有限公司 | A kind of containing rare earth moisture-proof H 2the seamless steel pipe for gas cylinder of S corrosion and production method thereof |
| CN103741028B (en) * | 2013-12-31 | 2016-04-13 | 攀钢集团成都钢钒有限公司 | Low yield strength ratio low temperature weldless steel tube and production method thereof |
| CN104372239B (en) * | 2014-10-14 | 2017-01-18 | 山东钢铁股份有限公司 | Vanadium-nitrogen microalloyed high-strength phase-transformation induced plastic steel seamless pipe and preparation method thereof |
| DE112016000288T5 (en) * | 2015-01-07 | 2017-10-19 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | HOLLOW SEAMLESS STEEL TUBE FOR ONE SPRING |
| CN105603313B (en) * | 2016-01-25 | 2017-09-22 | 宝山钢铁股份有限公司 | A kind of low yield strength ratio oil casing pipe steel and manufacture method and the production method of sleeve pipe |
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2019
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