CN105624584B - A kind of extremely frigid zones K65 controlled rollings steel plate, straight-line joint submerged arc welding tube and its manufacture method - Google Patents
A kind of extremely frigid zones K65 controlled rollings steel plate, straight-line joint submerged arc welding tube and its manufacture method Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 152
- 239000010959 steel Substances 0.000 title claims abstract description 152
- 238000003466 welding Methods 0.000 title claims abstract description 127
- 238000005096 rolling process Methods 0.000 title claims abstract description 66
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 22
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 21
- 229910001563 bainite Inorganic materials 0.000 claims abstract description 13
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 12
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 12
- 229910052802 copper Inorganic materials 0.000 claims abstract description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 9
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 9
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 8
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 7
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 6
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 4
- 238000007689 inspection Methods 0.000 claims description 31
- 230000008569 process Effects 0.000 claims description 18
- 238000012360 testing method Methods 0.000 claims description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 12
- 238000003801 milling Methods 0.000 claims description 12
- 238000001816 cooling Methods 0.000 claims description 10
- 239000000463 material Substances 0.000 claims description 9
- 238000005452 bending Methods 0.000 claims description 7
- 238000003825 pressing Methods 0.000 claims description 6
- 239000006247 magnetic powder Substances 0.000 claims description 5
- 230000009467 reduction Effects 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 5
- 230000002706 hydrostatic effect Effects 0.000 claims description 3
- 238000003754 machining Methods 0.000 claims description 3
- 238000005516 engineering process Methods 0.000 abstract description 2
- 238000005275 alloying Methods 0.000 abstract 1
- 238000009740 moulding (composite fabrication) Methods 0.000 description 14
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 239000010953 base metal Substances 0.000 description 4
- 238000011161 development Methods 0.000 description 4
- 238000009863 impact test Methods 0.000 description 4
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- 238000010276 construction Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
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- 238000004080 punching Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
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Abstract
The invention discloses a kind of extremely frigid zones K65 controlled rollings steel plate, straight-line joint submerged arc welding tube and its manufacture method, belong to submerged-arc welded (SAW) pipe manufacturing technology field.The present invention K65 controlled rolling steel plate each component mass percents be：C0.04 0.08%, Mn 1.50 1.75%, Si 0.20 0.35%, S≤0.006%, P≤0.010%, Ni≤0.23%, Mo≤0.009%, Ti≤0.020%, Al 0.025 0.050%, Nb 0.06 0.09%, N≤0.01%, Cu≤0.25%, Cr 0.10 0.30%, B≤0.0005%, V+Nb+Ti 0.085% 0.224%, surplus Fe；Wherein Ceq≤0.43, Pcm≤0.20；Bainite content 45 65% in the microscopic structure of the K65 controlled rollings steel plate, ferrite content 35 55%.The present invention makes gained K65 controlled rolling steel plates have good low-temperature impact toughness and DWTT performances, used suitable for manufacture extremely frigid zones, diameter by optimizing K65 controlled rolling steel plates alloying component, rolling technological parameter
Description
Technical Field
The invention relates to a K65 controlled rolling steel plate for alpine regions, a longitudinal submerged arc welded pipe and a manufacturing method thereof, belonging to the technical field of manufacturing of submerged arc welded pipes.
Background
With the development of oil and gas resource exploration and development to remote areas, the construction of conveying pipelines in alpine regions becomes a hot spot. In the past, oil and gas pipelines in alpine regions always adopt a technical route with large caliber and low pressure, the highest conveying pressure is lower than 9.8MPa, and K60-grade steel pipes are mainly adopted. In recent years, the international trend is being pursuedThe development of oil and gas pipeline technology makes great progress, the construction of oil and gas pipelines in such areas is also developing to higher pressure and larger delivery capacity, and the single-pipe gas transmission capacity reaches 450-500 hundred million m3The level of/a (cubic meter per year) represents the development direction of oil and gas transmission pipelines in alpine regions. Because the pipelines are all large-output long-distance pipelines and have the characteristics of high steel pipe strength, large wall thickness and high low-temperature toughness requirement, the high requirements are provided for the component design and the smelting and rolling process of the plate, and the forming, welding and inspection of the steel pipe are also serious challenges. The concrete points are as follows:
strict low temperature impact toughness performance requirements: in order to ensure the safe use of the steel pipe in polar regions or alpine regions, the DWTT test (drop weight tear test) temperature of the steel plate is required to be-35 ℃, the average minimum requirement of the shearing area is 85 percent, and the single minimum requirement is 70 percent; the CVN test (charpy impact test) temperature of the weld and hot zone was-40 ℃, the minimum requirement for the average of 3 samples absorbing energy was 60J, and the individual minimum requirement was 50J.
In the process of implementing the invention, the inventor finds that at least the following problems exist in the prior art: in the prior art, the performance of a steel pipe base material, a steel pipe welding line and a hot area at low temperature cannot meet the requirement, so that the steel pipe cannot be used in a severe cold area.
Disclosure of Invention
The invention aims to solve the technical problem that the K65 controlled rolled steel plate, the longitudinal submerged arc welded pipe and the manufacturing method thereof for the alpine region are provided, and the obtained K65 controlled rolled steel plate and K65 steel longitudinal submerged arc welded pipe have the advantages that the low-temperature impact toughness and the DWTT performance meet the requirements of use in the alpine region.
Specifically, the method comprises the following technical scheme:
the invention provides a K65 controlled rolling steel plate for alpine regions, which comprises the following components in percentage by mass: 0.04 to 0.08 percent of C, 1.50 to 1.75 percent of Mn, 0.20 to 0.35 percent of Si, less than or equal to 0.006 percent of S, less than or equal to 0.010 percent of P, less than or equal to 0.23 percent of Ni, less than or equal to 0.009 percent of Mo, less than or equal to 0.020 percent of Ti, 0.025 to 0.050 percent of Al, 0.06 to 0.09 percent of Nb0.01 percent of N, less than or equal to 0.25 percent of Cu, 0.10 to 0.30 percent of Cr, less than or equal to 0.0005 percent of B, 0.085 to 0.224 percent of V + Nb +; wherein Ceq is less than or equal to 0.43, Pcm is less than or equal to 0.20; the bainite content of the microstructure of the K65 controlled rolling steel plate is 45-65%, and the ferrite content is 35-55%.
Further, the K65 controlled rolling steel plate comprises the following components in percentage by mass: 0.04 to 0.06 percent of C, 1.59 to 1.66 percent of Mn1, 0.20 to 0.24 percent of Si, less than or equal to 0.003 percent of S, less than or equal to 0.010 percent of P, less than or equal to 0.20 percent of Ni, less than or equal to 0.008 percent of Mo, less than or equal to 0.020 percent of Ti, 0.036 to 0.042 percent of Al, 0.06 to 0.09 percent of Nb, less than or equal to 0.01 percent of N, less than or equal to 0.25 percent of Cu, 0.218 to 0.229 percent of CrB, less than or equal to 0.0002 percent of B, 0.086 to 0.; wherein Ceq is less than or equal to 0.41, and Pcm is less than or equal to 0.17.
Further, the shear area ratio of the K65 controlled rolled steel plate in a drop weight tear test at-35 ℃ is 75-95%.
The second aspect of the present invention provides a rolling method of the K65 controlled rolling steel sheet of the first aspect of the present invention, wherein: the steel billet with the components in percentage by mass in the first aspect of the invention is adopted, the initial rolling temperature of the intermediate billet is 880-950 ℃, the final rolling temperature of the steel plate is 60-70 ℃ above the Ar3 temperature, the accelerated cooling strength of the steel plate is 12-20 ℃/s, and the final cooling temperature is 300-500 ℃.
The third aspect of the invention provides a K65 steel longitudinal submerged arc welded pipe for alpine regions, wherein the K65 steel longitudinal submerged arc welded pipe is formed by bending and welding K65 controlled rolled steel plates in the first aspect of the invention; the welding seam chemical components of the K65 steel longitudinal submerged arc welded pipe are as follows by mass percent: 0.04 to 0.08 percent of C, 1.65 to 2.0 percent of Mn, 0.25 to 0.35 percent of Si, less than or equal to 0.01 percent of S, less than or equal to 0.015 percent of P, 0.05 to 0.35 percent of Ni, 0.1 to 0.20 percent of Mo, less than or equal to 0.06 percent of V, less than or equal to 0.025 percent of Ti, less than or equal to 0.030 percent of Al, less than or equal to 0.06 percent of Nb, less than or equal to 0.010 percent of N, less than or equal to 0.20 percent of Cu, less than or equal to 0.20 percent of; wherein Ceq is 0.40-0.45, Pcm is less than or equal to 0.22; the ferrite content in the weld microstructure is more than 85%.
In a fourth aspect of the present invention, there is provided a method for producing a longitudinal submerged arc welded pipe of K65 steel according to the third aspect of the present invention, comprising using as a base material a K65 controlled rolling steel plate according to the first aspect of the present invention; the manufacturing method comprises the following steps: the method comprises the following steps of edge milling, edge pre-bending, JCO forming, pre-welding, inner welding, outer welding, first ultrasonic inspection, first X-ray inspection, mechanical diameter expanding, hydrostatic test, chamfering, groove machining, second ultrasonic inspection, second X-ray inspection, pipe end magnetic powder inspection and appearance quality inspection.
Specifically, in the edge milling step, the height of the upper groove is 8.0-8.5mm, and the thickness of the truncated edge is 9.0-9.5 mm.
Specifically, in the JCO forming step, the pressing pass is 27, and the reduction amount is 580-590 mm.
Specifically, in the internal welding step, four-wire submerged arc automatic welding is adopted to weld on the welding groove at the inner side of the steel pipe, the first wire is in direct current reverse connection, and the second wire, the third wire, the fourth wire and the fourth wire are in alternating current; the steel pipe welding process parameters are as follows: the first filament current I is 1000-1100A, and the voltage U is 32-36V; the second filament current I is 900-1000A, and the voltage U is 30-35V; the third filament current I is 700-800A, and the voltage U is 35-40V; the fourth filament current I is 600-700A, and the voltage U is 40-44V; the distance d between the welding wires is 30-35mm, the welding speed V is 110-150cm/min, and the linear energy is 45-56 KJ/cm.
Specifically, in the external welding step, four-wire submerged arc automatic welding is adopted to weld on a welding groove on the outer side of the steel pipe, the first wire is in direct current reverse connection, and the second wire, the third wire, the fourth wire and the fourth wire are in alternating current; the steel pipe welding process parameters are as follows: the first filament current I is 1100-1200A, and the voltage U is 32-36V; the second filament current I is 900-1000A, and the voltage U is 30-35V; the third filament current I is 700-800A, and the voltage U is 35-40V; the fourth filament current I is 600-700A, and the voltage U is 40-44V; the distance d between the welding wires is 30-35mm, the welding speed V is 110-150cm/min, and the linear energy is 55-60 KJ/cm.
The invention has the beneficial effects that:
(1) and the steel plate has better low-temperature impact toughness and low-temperature DWTT performance by controlling the alloy components of the K65 controlled steel rolling plate and controlling the microstructure by optimizing the rolling process parameters.
(2) The problem that welding secondary thermal cycle grains are thick and thick to cause toughness deterioration of a hot zone is effectively solved by reasonably designing the size of the groove, and low-temperature impact toughness of the hot zone is guaranteed.
(3) And the welding line obtains proper penetration depth and good performance by reasonably setting the current, voltage, angle, welding wire interval and welding speed of each wire in the welding process. The welding seam finally obtains a structure which is mainly made of acicular ferrite and has good obdurability, and the problem that the obdurability of the steel pipe is reduced due to local heating in the welding process is solved.
The technical scheme of the invention is suitable for manufacturing the diameterThe wall thickness of the K65 steel longitudinal submerged arc welded pipe is 23-27.7mm for alpine regions.
Drawings
FIG. 1 is a photograph of a coarse grain zone microstructure of a weld of a longitudinal submerged arc welded pipe obtained in example 4 of the present invention;
FIG. 2 is a photograph of the fine grain zone microstructure of the weld of the submerged arc longitudinal welded pipe obtained in example 4 of the present invention.
Detailed Description
In order to make the technical solutions and advantages of the present invention clearer, the following describes embodiments of the present invention in further detail.
The invention provides a K65 controlled rolling steel plate for alpine regions, which comprises the following components in percentage by mass: 0.04 to 0.08 percent of C, 1.50 to 1.75 percent of Mn, 0.20 to 0.35 percent of Si, less than or equal to 0.006 percent of S, less than or equal to 0.010 percent of P, less than or equal to 0.23 percent of Ni, less than or equal to 0.009 percent of Mo, less than or equal to 0.020 percent of Ti, 0.025 to 0.050 percent of Al, 0.06 to 0.09 percent of Nb0.01 percent of N, less than or equal to 0.25 percent of Cu, 0.10 to 0.30 percent of Cr, less than or equal to 0.0005 percent of B, 0.085 to 0.224 percent of V + Nb +; wherein Ceq is less than or equal to 0.43(Ceq is carbon equivalent, the calculation formula is Ceq ═ C + Mn/6+ (Cr + Mo + V)/5+ (Ni + Cu)/15, the element symbol in the formula represents the element content), Pcm is less than or equal to 0.20(Pcm is welding crack sensitivity index, the calculation formula is C + Si/30+ (Mn + Cu + Cr)/20+ Ni/60+ Mo/15+ V/10+5B, the element symbol in the formula represents the element content). The bainite content of the microstructure of the K65 controlled rolling steel plate is 45-65%, and the ferrite content is 35-55%.
In the above-mentioned K65 controlled rolling steel sheet, the mass percentages of the components are preferably: 0.04 to 0.06 percent of C, 1.59 to 1.66 percent of Mn1, 0.20 to 0.24 percent of Si, less than or equal to 0.003 percent of S, less than or equal to 0.010 percent of P, less than or equal to 0.20 percent of Ni, less than or equal to 0.008 percent of Mo, less than or equal to 0.020 percent of Ti, 0.036 to 0.042 percent of Al, 0.06 to 0.09 percent of Nb, less than or equal to 0.01 percent of N, less than or equal to 0.25 percent of Cu, 0.218 to 0.229 percent of CrB, less than or equal to 0.0002 percent of B, 0.086 to 0.; wherein Ceq is less than or equal to 0.41, and Pcm is less than or equal to 0.17.
As known in the art, the content of each element in the controlled rolling steel plate and the bainite and ferrite ratio in the microstructure thereof have an important influence on the properties of the finally obtained controlled rolling steel plate. The K65 controlled rolling steel plate is used for manufacturing longitudinal submerged arc welded pipes which can be used in alpine regions, so that the low-temperature DWTT performance of the steel plate is high in requirement. Because the low-temperature DWTT performance of the steel plate obtained according to the content of each component of the commonly used controlled rolling steel plate in the prior art can not meet the requirement of using the steel plate in a high and cold area, the inventor adjusts the content of each element in the K65 controlled rolling steel plate, and particularly, the content of C, Ni, Mo and Nb is greatly different from the common knowledge in the prior art in the field. For example, the mass percent of C in the prior art is more than 0.12 percent, while the mass percent of C in the invention is only 0.04-0.08 percent; in the prior art, the mass percent of Ni is about 0.5 percent, but the mass percent of Ni is only below 0.2 percent; the mass percent of Mo in the prior art is about 0.3%, while the mass percent of Mo in the invention is below 0.009%.
Because the impact toughness of the bainite is good, the proportion of the bainite in the microstructure of the steel pipe base metal plate is improved, and the low-temperature DWTT performance of the steel pipe base metal is favorably improved. And ferrite has good corrosion resistance. Therefore, in order to improve the low-temperature DWTT performance while maintaining the strength, corrosion resistance, etc. of the steel sheet, it is necessary to control the ratio of bainite to ferrite in the microstructure of the steel sheet. The bainite content of the microstructure of the K65 controlled rolling steel plate is 45-65%, and the ferrite content is 35-55%, so that the obtained K65 controlled rolling steel plate has good low-temperature DWTT performance, and the performance of other aspects can also meet the requirements.
In conclusion, the inventor obtains the K65 controlled rolling steel plate with good low-temperature DWTT performance by adjusting the content of each component in the K65 controlled rolling steel plate and the proportion of bainite and ferrite in a microstructure. The shear area rate of the obtained K65 controlled rolling steel plate at-35 ℃ reaches 75-95%, and the average value reaches more than 85%.
Since the K65 controlled rolled steel sheet of the first aspect of the invention defines the bainite to ferrite ratio in the microstructure, the above-described K65 controlled rolled steel sheet can be obtained by optimizing the rolling process.
The second aspect of the present invention provides a rolling method of the K65 controlled rolling steel sheet of the first aspect of the present invention, wherein: the steel billet with the components in percentage by mass in the first aspect of the invention is adopted, the initial rolling temperature of the intermediate billet is 880-950 ℃, the final rolling temperature of the steel plate is 60-70 ℃ above the Ar3 temperature, the accelerated cooling strength of the steel plate is 12-20 ℃/s, and the final cooling temperature is 300-500 ℃. The microstructure composition of the K65 controlled rolled steel plate obtained by the rolling process can meet the requirements of the first aspect of the invention. The Ar3 temperature is the critical temperature for transformation from austenite to ferrite in the microstructure of the steel sheet base material, and those skilled in the art can determine the Ar3 temperature according to the knowledge in the art.
The third aspect of the invention provides a K65 steel longitudinal submerged arc welded pipe for alpine regions, wherein the K65 steel longitudinal submerged arc welded pipe is formed by bending and welding K65 controlled rolled steel plates in the first aspect of the invention; the welding seam chemical components of the K65 steel longitudinal submerged arc welded pipe are as follows by mass percent: 0.04 to 0.08 percent of C, 1.65 to 2.0 percent of Mn, 0.25 to 0.35 percent of Si, less than or equal to 0.01 percent of S, less than or equal to 0.015 percent of P, 0.05 to 0.35 percent of Ni, 0.1 to 0.20 percent of Mo, less than or equal to 0.06 percent of V, less than or equal to 0.025 percent of Ti, less than or equal to 0.030 percent of Al, less than or equal to 0.06 percent of Nb, less than or equal to 0.010 percent of N, less than or equal to 0.20 percent of Cu, less than or equal to 0.20 percent of; wherein Ceq is 0.40-0.45, Pcm is less than or equal to 0.22; the ferrite content in the weld microstructure is more than 85%. The ferrite has good toughness, so that the improvement of the content of the ferrite in a weld microstructure is beneficial to the improvement of the low-temperature impact toughness of the steel pipe.
In a fourth aspect of the present invention, there is provided a method for producing a longitudinal submerged arc welded pipe of K65 steel according to the third aspect of the present invention, comprising using as a base material a K65 controlled rolling steel plate according to the first aspect of the present invention; the manufacturing method comprises the following steps: the method comprises the following steps of edge milling, edge pre-bending, JCO forming, pre-welding, inner welding, outer welding, first ultrasonic inspection, first X-ray inspection, mechanical diameter expanding, hydrostatic test, chamfering, groove machining, second ultrasonic inspection, second X-ray inspection, pipe end magnetic powder inspection and appearance quality inspection.
In the edge milling step, aiming at the characteristic of larger thickness of the steel plate, the upper groove height is properly increased, the upper groove height is 8.0-8.5mm, and the truncated edge thickness is 9.0-9.5 mm. The secondary heat circulation area moves downwards or disappears, complete penetration in the welding process is ensured, and the quality of a welding joint is ensured.
The JCO forming process comprises the following steps: punching one half of the steel plate subjected to edge pre-bending for multiple times by using a JCO forming machine to form a J shape, punching the other half of the steel plate for multiple times to form a C shape, and finally pressing the steel plate in the middle of the steel plate for one time to form an opened O shape; in the process, the total pressing pass is 27, and the reduction is 580-590 mm.
In the internal welding process and the external welding process, four-wire submerged arc automatic welding is adopted to weld on the inner side (or the outer side) welding groove of the steel pipe, and the used welding wire is Mn-Mo-Ti-B series welding wire; when the welding parameters are determined, the action of each wire in four-wire welding is fully considered, meanwhile, the influence of the difference of the internal and external welding heat input on the impact performance of the welding heat affected zone of the steel pipe and the influence of the wall thickness on the impact performance of the heat affected zone are considered, and the proper welding parameters and the internal and external welding heat input are determined for welding, so that the problem that the toughness is seriously reduced due to the secondary heat circulation of welding is solved, and the welding seam and the hot zone have excellent low-temperature impact toughness. Wherein,
in the internal welding step, the first wire is in direct current reverse connection, and the second wire, the fourth wire and the third wire are in alternating current; the steel pipe welding process parameters are as follows: the first filament current I is 1000-1100A, and the voltage U is 32-36V; the second filament current I is 900-1000A, and the voltage U is 30-35V; the third filament current I is 700-800A, and the voltage U is 35-40V; the fourth filament current I is 600-700A, and the voltage U is 40-44V; the distance d between the welding wires is 30-35mm, the welding speed V is 110-150cm/min, and the linear energy is 45-56 KJ/cm.
In the external welding step, the first wire is in direct current reverse connection, and the second wire, the fourth wire and the third wire are in alternating current; the steel pipe welding process parameters are as follows: the first filament current I is 1100-1200A, and the voltage U is 32-36V; the second filament current I is 900-1000A, and the voltage U is 30-35V; the third filament current I is 700-800A, and the voltage U is 35-40V; the fourth filament current I is 600-700A, and the voltage U is 40-44V; the distance d between the welding wires is 30-35mm, the welding speed V is 110-150cm/min, and the linear energy is 55-60 KJ/cm.
The technical scheme of the invention does not specially improve the steps except for edge milling, JCO forming and welding in the K65 steel longitudinal submerged arc welded pipe manufacturing method, and a person skilled in the art can complete the rest steps according to actual needs and technical knowledge in the field.
In conclusion, the K65 controlled rolling steel plate has good low-temperature impact toughness and DWTT performance by optimizing the alloy components and the rolling process parameters of the K65 controlled rolling steel plate; the process parameters of the steps of edge milling, JCO forming and welding in the steel pipe manufacturing process are optimized, so that the low-temperature impact toughness and DWTT performance of the obtained steel pipe welding line and the hot area can meet the requirements for use in alpine regions; therefore, the obtained K65 steel longitudinal submerged arc welded pipe can be normally used in alpine regions, and the safety is ensured.
In the embodiment of the invention, the Charpy impact test is carried out according to the ASTM A370-2012 standard; DWTT tests were performed according to SY/T6476-2007 standard.
Example 1
This example provides a K65 controlled rolled steel sheet having a width of 4355mm and a thickness of 23 mm.
The mass percentages of the components of the K65 controlled rolling steel plate are shown in the table 1:
TABLE 1 weight percentages of components of K65 controlled rolled steel plate in this example
| C | Mn | Si | P | S | Mo | Ni | Cr |
| 0.04-0.05 | 1.60-1.66 | 0.20-0.24 | 0.007-0.01 | 0.001-0.003 | 0.007-0.008 | 0.218-0.224 | 0.223-0.229 |
| Cu | Al | N | B | (V+Nb+Ti)％ | Ceq％ | Pcm％ | Fe |
| 0.132-0.144 | 0.036-0.041 | 0.004-0.006 | 0.0001-0.0002 | 0.091-0.099 | 0.39 | 0.16 | Balance of |
The rolling process parameters are as follows: the steel billets with the components in percentage by mass shown in the table 1 are adopted, the initial rolling temperature of the intermediate billet is 880-950 ℃, the final rolling temperature of the steel plate is 60-70 ℃ above the Ar3 temperature, the accelerated cooling strength of the steel plate is 12-20 ℃/s, and the final cooling temperature is 300-500 ℃.
The bainite content of the microstructure of the obtained K65 controlled rolled steel plate is 46-64%, and the ferrite content is 37-54%.
The DWTT performance of the obtained K65 controlled rolled steel sheet was tested. The results are shown in Table 2. As can be seen from Table 2, by optimizing the alloy components and the rolling process parameters, the average value of the shear area rate of the K65 controlled rolling steel plate of the K65 controlled rolling steel plate of the invention reaches more than 85%, and the shear area rate of each sample reaches more than 70%, so that the requirements of alpine regions on the steel pipe base metal are met.
TABLE 2 DWTT test results for the K65 controlled rolled steel sheet of this example
Example 2
This example provides a K65 controlled rolled steel sheet having a width of 4340mm and a thickness of 27.7 mm.
The mass percentages of the components of the K65 controlled rolling steel plate are shown in Table 3:
TABLE 3 weight percentages of components of K65 controlled rolled steel plate in this example
| C | Mn | Si | P | S | Mo | Ni | Cr |
| 0.04-0.06 | 1.59-1.65 | 0.20-0.23 | 0.006-0.01 | 0.001-0.003 | 0.007-0.008 | 0.211-0.229 | 0.218-0.227 |
| Cu | Al | N | B | (V+Nb+Ti)％ | Ceq％ | Pcm％ | Fe |
| 0.133-0.147 | 0.036-0.042 | 0.004-0.005 | 0.0001-0.0002 | 0.086-0.222 | 0.37-0.41 | 0.15-0.17 | Balance of |
The rolling process parameters are as follows: the steel billet with the components in percentage by mass is adopted, the initial rolling temperature of the intermediate billet is 880-950 ℃, the final rolling temperature of the steel plate is 60-70 ℃ above the Ar3 temperature, the accelerated cooling strength of the steel plate is 12-20 ℃/s, and the final cooling temperature is 300-500 ℃.
The bainite content of the microstructure of the obtained K65 controlled rolled steel plate is 45-63%, and the ferrite content is 35-52%.
The DWTT performance of the obtained K65 controlled rolled steel sheet was tested. The results are shown in Table 4. As can be seen from Table 4, by optimizing the alloy components and the rolling process parameters, the average value of the shear area rate of the K65 controlled rolling steel plate reaches more than 85%, the shear area rate of each sample reaches more than 70%, and the requirements of alpine regions on the steel pipe base metal are met.
TABLE 4 DWTT test results for the K65 controlled rolled steel sheet of this example
Example 3
This embodiment provides a diameterK65 steel longitudinal submerged arc welded pipe with thickness of 23mm and a manufacturing method thereof.
The steel pipe of this example was formed by using the K65 controlled rolling steel sheet obtained in example 1 as a base material, and subjecting the base material to edge milling, pre-flanging, JCO forming, pre-welding, inner welding, outer welding, first ultrasonic inspection, first X-ray inspection, mechanical diameter expansion, water pressure test, chamfering, groove forming, second ultrasonic inspection, second X-ray inspection, pipe end magnetic powder inspection, and appearance quality inspection. Wherein,
in the edge milling step, the angles of the upper and lower grooves are both 35 degrees, the height of the upper groove is 8.0mm, and the thickness of the truncated edge is 6.5 mm.
In the JCO forming step: the whole pressing pass is 27 passes, and the reduction amount is 585 mm.
In the inner welding step: adopting four-wire submerged arc automatic welding to weld the inner side welding groove of the steel pipe, wherein the used welding wire is Mn-Mo-Ti-B series welding wire (model: Tunion SA Ni3/T-UV621), and the welding technological parameters are as follows: the welding wire comprises a first wire current 1150A, a voltage 34V, a second wire current 950A, a voltage 38V, a third wire current 800A, a voltage 40V, a fourth wire current 700A, a voltage 42V, a welding wire interval of 33mm, a welding speed of 135mm/min and welding wire energy of 45.6 kJ/cm.
External welding: adopting four-wire submerged arc automatic welding to weld the welding groove at the outer side of the steel pipe, wherein the used welding wire is Mn-Mo-Ti-B series welding wire (model: Tunion SA Ni3/T-UV621), and the welding process parameters are as follows: the welding wire comprises a first wire current 950A, a voltage 32V, a second wire current 800A, a voltage 38V, a third wire current 700A, a voltage 40V, a fourth wire current 600A, a voltage 42V, a welding wire interval of 33mm, a welding speed of 150mm/min and a welding wire energy of 48.3 kJ/cm.
The chemical components of the obtained welding seam are 0.045% by mass, 1.663% by mass, 0.30% by mass, 0.0035% by mass, 0.009% by mass, 0.147% by mass, 0.119% by mass, 0.003% by mass, 0.018% by mass, 0.017% by mass, 0.047% by mass, 0.009% by mass, 0.095% by mass, 0.165% by mass and 0.0005% by mass, the balance being Fe, wherein Ceq is 0.40, Pcm is 0.16, and the microstructure of the welding seam is that the content of acicular ferrite is more than 85%.
The charpy impact properties of the resulting steel pipe welds and hot zones were tested separately and the experimental results are shown in table 5. As can be seen from Table 5, the average value of the Charpy impact energy of the welding seam and the hot area of the K65 steel longitudinal submerged arc welded pipe manufactured by the technical scheme of the invention reaches more than 60J, the numerical value of each sample also reaches more than 50J, the low temperature resistance is good, and the requirements of high and cold regions on steel pipes are met.
TABLE 5 Charpy impact test results of the weld and hot zone of the steel pipes of this example
Example 4:
this embodiment provides a diameter ofA K65 steel longitudinal submerged arc welded pipe with the thickness of 27.7mm and a manufacturing method thereof.
The steel pipe of this example was formed by using the K65 controlled rolling steel sheet obtained in example 2 as a base material, and subjecting the base material to edge milling, pre-flanging, JCO forming, pre-welding, inner welding, outer welding, first ultrasonic inspection, first X-ray inspection, mechanical diameter expansion, water pressure test, chamfering, groove forming, second ultrasonic inspection, second X-ray inspection, pipe end magnetic powder inspection, and appearance quality inspection. Wherein,
edge milling: the angles of the upper and lower grooves are both 35 degrees, the height of the upper groove is fixed to be 8.0mm, the thickness of the truncated edge is 9.2mm,
JCO forming: the whole pressing pass is 27 passes, and the reduction amount is 585 mm.
And (3) internal welding: adopting four-wire submerged arc automatic welding to weld on the inner side welding groove of the steel pipe, wherein the used welding wire is Mn-Mo-Ti-B series welding wire (model: Tunion SA Ni3/T-UV621), and the welding process comprises the following steps: first wire current 1150A, voltage 34V; second filament current 950A, voltage 38V; third filament current 800A, voltage 40V; fourth filament current 700A, voltage 42V; the spacing between the welding wires is 33 mm; the welding speed was 125mm/min and the energy of the welding line was 57 kJ/cm.
An outer welding step: the welding wire is Mn-Mo-Ti-B series welding wire (model: T unit SA Ni3/T-UV621), and the welding process comprises the following steps: a first filament current 1200A, voltage 34V; second filament current 950A, voltage 38V; third filament current 800A, voltage 40V; fourth filament current 700A, voltage 42V; the spacing between the welding wires is 32 mm; the welding speed was 135mm/min, and the welding line energy was 57.2 kJ/cm.
The chemical components of the obtained welding seam are 0.045% by mass, 1.663% by mass, 0.30% by mass, 0.0035% by mass, 0.009% by mass, 0.147% by mass, 0.119% by mass, 0.003% by mass, 0.018% by mass, 0.017% by mass, 0.047% by mass, 0.009% by mass, 0.095% by mass, 0.165% by mass and 0.0005% by mass, the balance being Fe, wherein Ceq is 0.40, Pcm is 0.16, and the microstructure of the welding seam is that the content of acicular ferrite is more than 85%.
The photographs of the coarse grain region and the fine grain region of the weld of the longitudinal submerged arc welded pipe obtained in this example are shown in fig. 1 and fig. 2, respectively.
The charpy impact properties of the resulting steel pipe welds and hot zones were tested separately and the experimental results are shown in table 6. As can be seen from Table 6, the average value of the Charpy impact energy of the welding line and the hot area of the K65 steel longitudinal submerged arc welded pipe manufactured by the technical scheme of the invention reaches more than 60J, the numerical value of each sample also reaches more than 50J, the low temperature resistance is good, and the requirements of high and cold regions on steel pipes are met.
TABLE 6 Charpy impact test results of the weld and hot zone of the steel pipes of this embodiment
The above description is only for facilitating the understanding of the technical solutions of the present invention by those skilled in the art, and is not intended to limit the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A steel sheet controlled by K65 for alpine regions is characterized in that: the K65 controlled rolled steel plate is used for manufacturing longitudinal submerged arc welded pipes for alpine regions, and the K65 controlled rolled steel plate comprises the following components in percentage by mass: 0.04 to 0.06 percent of C, 1.59 to 1.66 percent of Mn, 0.20 to 0.24 percent of Si, less than or equal to 0.003 percent of S, less than or equal to 0.010 percent of P, less than or equal to 0.20 percent of Ni, less than or equal to 0.008 percent of Mo, less than or equal to 0.020 percent of Ti, 0.036 to 0.042 percent of Al, 0.06 to 0.09 percent of Nb, less than or equal to 0.01 percent of N, less than or equal to 0.25 percent of Cu, 0.218 to 0.229 percent of Cr, less than or equal to 0.0002 percent of B, 0.086 to 0.222 percent; wherein Ceq is less than or equal to 0.41, and Pcm is less than or equal to 0.17; the bainite content of the microstructure of the K65 controlled rolling steel plate is 45-65%, and the ferrite content is 35-55%; the shear area rate of the K65 controlled rolling steel plate in a drop weight tear test at-35 ℃ is 75-95%.
2. A rolling method of a K65 controlled rolled steel sheet according to claim 1, wherein the rolling method comprises: the steel blank with the components in percentage by mass as claimed in claim 1 is adopted, the initial rolling temperature of the intermediate blank is 880-950 ℃, the final rolling temperature of the steel plate is 60-70 ℃ above the Ar3 temperature, the accelerated cooling strength of the steel plate is 12-20 ℃/s, and the final cooling temperature is 300-500 ℃.
3. A K65 steel longitudinal submerged arc welded pipe for alpine regions is characterized in that the K65 steel longitudinal submerged arc welded pipe is formed by bending and welding K65 controlled rolled steel plates according to claim 1; the welding seam chemical components of the K65 steel longitudinal submerged arc welded pipe are as follows by mass percent: 0.04 to 0.08 percent of C, 1.65 to 2.0 percent of Mn, 0.25 to 0.35 percent of Si, less than or equal to 0.01 percent of S, less than or equal to 0.015 percent of P, 0.05 to 0.35 percent of Ni, 0.1 to 0.20 percent of Mo, less than or equal to 0.06 percent of V, less than or equal to 0.025 percent of Ti, less than or equal to 0.030 percent of Al, less than or equal to 0.06 percent of Nb, less than or equal to 0.010 percent of N, less than or equal to 0.20 percent of Cu, less than or equal to 0.20 percent of; wherein Ceq is 0.40-0.45, Pcm is less than or equal to 0.22; the ferrite content in the weld microstructure is more than 85%.
4. A method for manufacturing a K65 steel submerged arc welded longitudinal welded pipe according to claim 3, wherein the K65 controlled rolling steel plate according to claim 1 is used as a base material; the manufacturing method comprises the following steps: the method comprises the following steps of edge milling, edge pre-bending, JCO forming, pre-welding, inner welding, outer welding, first ultrasonic inspection, first X-ray inspection, mechanical diameter expanding, hydrostatic test, chamfering, groove machining, second ultrasonic inspection, second X-ray inspection, pipe end magnetic powder inspection and appearance quality inspection;
in the edge milling step, the height of an upper groove is 8.0-8.5mm, and the thickness of a truncated edge is 9.0-9.5 mm;
in the internal welding step, four-wire submerged arc automatic welding is adopted to weld the welding groove at the inner side of the steel pipe, the first wire adopts direct current reverse connection, and the second wire, the fourth wire and the fourth wire are alternating current; the steel pipe welding process parameters are as follows: the first filament current I is 1000-1100A, and the voltage U is 32-36V; the second filament current I is 900-1000A, and the voltage U is 30-35V; the third filament current I is 700-800A, and the voltage U is 35-40V; the fourth filament current I is 600-700A, and the voltage U is 40-44V; the distance d between the welding wires is 30-35mm, the welding speed V is 110-150cm/min, and the linear energy is 45-56 KJ/cm;
in the external welding step, four-wire submerged arc automatic welding is adopted to weld the welding groove on the outer side of the steel pipe, the first wire adopts direct current reverse connection, and the second wire, the fourth wire and the fourth wire are alternating current; the steel pipe welding process parameters are as follows: the first filament current I is 1100-1200A, and the voltage U is 32-36V; the second filament current I is 900-1000A, and the voltage U is 30-35V; the third filament current I is 700-800A, and the voltage U is 35-40V; the fourth filament current I is 600-700A, and the voltage U is 40-44V; the distance d between the welding wires is 30-35mm, the welding speed V is 110-150cm/min, and the linear energy is 55-60 KJ/cm.
5. The manufacturing method according to claim 4, characterized in that: in the JCO forming step, the pressing pass is 27, and the rolling reduction is 580-590mm each time.
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