CN117244960A - Technological method for improving bending fatigue resistance of continuous pipe - Google Patents
Technological method for improving bending fatigue resistance of continuous pipe Download PDFInfo
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- CN117244960A CN117244960A CN202210648526.5A CN202210648526A CN117244960A CN 117244960 A CN117244960 A CN 117244960A CN 202210648526 A CN202210648526 A CN 202210648526A CN 117244960 A CN117244960 A CN 117244960A
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- 238000005452 bending Methods 0.000 title claims abstract description 51
- 238000000034 method Methods 0.000 title claims abstract description 50
- 238000003466 welding Methods 0.000 claims abstract description 160
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 110
- 239000010959 steel Substances 0.000 claims abstract description 110
- 238000010438 heat treatment Methods 0.000 claims abstract description 35
- 230000008569 process Effects 0.000 claims abstract description 29
- 238000001816 cooling Methods 0.000 claims abstract description 24
- 238000005096 rolling process Methods 0.000 claims abstract description 21
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- 230000035939 shock Effects 0.000 claims abstract description 16
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- 238000009659 non-destructive testing Methods 0.000 claims abstract description 10
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- 238000003723 Smelting Methods 0.000 claims abstract description 5
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- 238000009749 continuous casting Methods 0.000 claims abstract description 5
- 238000005520 cutting process Methods 0.000 claims abstract description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
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- 238000005728 strengthening Methods 0.000 claims description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 7
- 229910052802 copper Inorganic materials 0.000 claims description 7
- 239000010949 copper Substances 0.000 claims description 7
- 238000002360 preparation method Methods 0.000 claims description 7
- 229910052782 aluminium Inorganic materials 0.000 claims description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 6
- 239000011888 foil Substances 0.000 claims description 5
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- 239000010937 tungsten Substances 0.000 description 2
- IADRPEYPEFONML-UHFFFAOYSA-N [Ce].[W] Chemical compound [Ce].[W] IADRPEYPEFONML-UHFFFAOYSA-N 0.000 description 1
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- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
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Classifications
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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
- B21C37/08—Making tubes with welded or soldered seams
- B21C37/0807—Tube treating or manipulating combined with, or specially adapted for use in connection with tube making machines, e.g. drawing-off devices, cutting-off
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/352—Working by laser beam, e.g. welding, cutting or boring for surface treatment
- B23K26/356—Working by laser beam, e.g. welding, cutting or boring for surface treatment by shock processing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/36—Removing material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/70—Auxiliary operations or equipment
- B23K26/702—Auxiliary equipment
-
- 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
- C21D10/00—Modifying the physical properties by methods other than heat treatment or deformation
- C21D10/005—Modifying the physical properties by methods other than heat treatment or deformation by laser shock processing
-
- 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
- C21D9/50—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for welded joints
-
- 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
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Plasma & Fusion (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Butt Welding And Welding Of Specific Article (AREA)
Abstract
The invention discloses a process method for improving bending fatigue resistance of a continuous pipe, which comprises the following steps: and (3) designing a coiled plate structure: the coiled plate structure is a dumbbell-shaped coiled plate; the manufacturing of the dumbbell-shaped coiled plate comprises the following steps: smelting, continuous casting into a blank, heating a casting blank, rough rolling, finish rolling, controlled cooling and curling; plate bending longitudinal shearing and plate butt welding: cutting the dumbbell-shaped coiled plate into a plurality of steel strips with equal width through a slitting machine set, connecting the plurality of steel strips end to end, and splicing the plurality of steel strips into a length required by a continuous pipe in a plate-to-plate welding mode; carrying out heat deformation treatment on the butt welding seams of the steel belts; laser shock reinforcement treatment of the butt welding seam of the steel belt; grinding, finishing and nondestructive testing are carried out on the welding line area to obtain continuous strip steel; and (3) forming and welding the continuous strip steel to form a tube to obtain the continuous tube. According to the invention, by increasing the wall thickness of the butt welding seam and optimizing the structure and performance of the butt welding seam, the bending fatigue resistance of the butt joint position of the oblique welding seam after the pipe is manufactured is greatly improved, and the service life of the continuous pipe is prolonged.
Description
Technical Field
The invention relates to the technical field of petroleum and natural gas pipe processing and manufacturing, in particular to a process method for improving bending fatigue resistance of a continuous pipe.
Background
Coiled Tubing (CT) is a new type petroleum tubing with a single length of thousands of meters and no screw connection, which is also called Coiled tubing, coiled tubing or Coiled tubing, and can be wound on a large diameter reel.
In the continuous tube manufacturing process, a plurality of sections of steel strips are welded together after being butted head and tail to form continuous steel strips, so that the target length of a continuous tube product is achieved, and therefore, a coil of continuous tube contains a plurality of circumferential butt welds formed by butt joint of a plurality of steel strips. In service, the butt welding seam position of the continuous pipe is always the weakest place of the whole continuous pipe, and the position is easy to generate problems of surface depression, wall thickness reduction, thorn leakage, fracture and the like under the action of composite loads such as pulling, pressing, bending fatigue and the like, so that the whole continuous pipe is scrapped. Analyzing the reasons of the weld, namely, when the butt welding seam of the steel belt is finished, the conditions of the weld seam excess height, oxidation edge burning and the like generated by welding are removed in a grinding mode and the like, so that the wall thickness of the butt welding seam is thinned, and the position of the welding seam is easy to bend and fatigue in the service process of the pipe, so that the pipe is invalid; on the other hand, the butt welding seam has larger difference between the structure and the performance of the butt welding seam and the base material, and meanwhile, a softening area with coarse structure and suddenly reduced hardness exists in the welding seam due to welding heat input, and the welding softening area is easy to fail firstly through bending fatigue, as shown in fig. 1. The prior art, such as the publication No. CN101898295A, discloses a method for manufacturing a high-strength high-ductility and toughness continuous tube, which is only considered in terms of tensile strength, hardness, yield strength and the like, and has no study on bending fatigue resistance.
Therefore, there is an urgent need to solve the above problems to improve the bending fatigue life of the coiled tubing, thereby further improving the quality of the domestic coiled tubing product.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a process method for improving the bending fatigue resistance of a continuous pipe. The invention greatly improves the bending fatigue resistance of the circumferential butt weld after pipe making by increasing the wall thickness of the butt weld and optimizing the structure and the performance of the butt weld, which reaches more than 100 percent of the service life of a parent pipe, is suitable for manufacturing low-carbon microalloy continuous pipes, and realizes the continuous pipes with high fatigue life and high quality.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a process method for improving bending fatigue resistance of a continuous pipe comprises the following steps:
and (3) designing a coiled plate structure:
the coiled plate structure is a dumbbell-shaped coiled plate;
manufacturing a dumbbell-shaped coiled plate:
the method comprises the following steps: smelting, continuous casting into a blank, heating a casting blank, rough rolling, finish rolling, controlled cooling and curling;
plate bending longitudinal shearing and plate butt welding;
cutting the dumbbell-shaped coiled plate into a plurality of steel strips with equal width through a slitting machine set, connecting the plurality of steel strips end to end, and splicing the plurality of steel strips into a length required by a continuous pipe in a plate-to-plate welding mode;
performing heat deformation treatment on the butt welding seam of the steel belt;
laser shock reinforcement treatment of the butt welding seam of the steel belt;
grinding, finishing and nondestructive testing are carried out on the welding line area to obtain continuous strip steel;
and (3) forming and welding the continuous strip steel to form a tube to obtain the continuous tube with bending fatigue resistance.
Further, the dumbbell-shaped coiled plate is divided into a front section, a middle section and a rear section along the length direction of the coiled plate, the thickness of the front section and the thickness of the rear section are equal, the thickness of the front section and the thickness of the rear section are larger than the thickness of the middle section, and the middle section is connected with the front section and the rear section through a smooth transition section;
the preparation method specifically comprises the following two forms:
firstly, the thicknesses of the front section and the rear section are symmetrical on two sides by taking the horizontal central line of the middle section as a reference; the coiled steel strip is cut into steel strips along the width direction, and after the steel strips are manufactured into tubes, a continuous tube with the outer diameter and the inner diameter changing is obtained;
second, the bottom surfaces of the front section, the middle section and the rear section are all on the same plane, and the upper surfaces of the front section and the rear section are higher than the middle section; the coiled steel strip is bent upwards to form a tube so as to obtain a continuous tube with unchanged outer diameter and changeable inner diameter; or bending the steel belt downwards to form a tube to obtain a continuous tube with the outer diameter being changed and the inner diameter being unchanged.
Further, the length of the middle section accounts for 75% -85% of the total length of the coiled plate, the front section and the rear section respectively account for 4% -6% of the total length of the coiled plate, the two smooth transition sections respectively account for 4% -6% of the total length of the coiled plate, and the thickness of the front section and the rear section is 104% -124% of the thickness of the middle section.
Further, the coil comprises the following chemical components in percentage by mass:
c:0.08%; si:0.20%; mn:0.80%; p:0.01%; s:0.003%; cu:0.28%; cr:0.50%; ni:0.20%; mo:0.3%; ti:0.015%; nb:0.03% of Fe and the balance of unavoidable impurities;
or is:
c:0.12%; si:0.23%; mn:1.4%; p:0.005%; s:0.004%; cu:0.23%; cr:0.60%; ni:0.14%; mo:0.13%; ti:0.02%; nb:0.03% of Fe and the balance of unavoidable impurities.
Further, the welding mode of the plate to plate is as follows: firstly, the ends of the front steel belt and the rear steel belt are processed into 45 degrees to 60 degrees, then the oblique butt joint is carried out, then the splice is held and fixed through a copper block with circulating water inside, and finally, the TIG welding, the filler wire or the plasma welding and the filler wire technology are adopted for welding.
Further, the thermal deformation treatment of the steel strip butt weld: adopting an intermediate frequency induction heating mode to rapidly heat the welding seam to 840-1000 ℃ for the first time, stopping heating, and applying 3-12 tons of rolling force or forging force perpendicular to the welding seam direction to further refine the welding seam structure; and then the welding seam is air-cooled to below 150 ℃, the welding seam is heated for the second time by adopting medium frequency induction, the heating temperature is 500-780 ℃, and the welding seam is naturally cooled, so that the residual stress caused by welding and thermal deformation is eliminated, and the hardness of the welding seam is improved.
Further, the laser shock peening of the steel strip butt weld: and removing the surplus height of the weld seam, and moving the butt weld seam to a laser reinforced numerical control workbench for laser impact treatment.
Further, the laser strengthening numerical control workbench adopts a Nd-YAG laser as a transmitting source, the pulse laser energy is 3-22J, the impact frequency is 1Hz, the wavelength is 1064nm, the pulse width is 10ns, the diameter of a light spot is 4mm, and the lap joint rate of the light spot is 33.3%; the aluminum foil is used as an absorption layer, and the thickness is 0.1mm; taking the uniform flowing water film as a constraint layer, wherein the thickness is 1.8-2.2mm; the laser beam and the surface of the welding line are always kept vertical in the laser impact process; spot path: the path length is the length of the oblique welding seam, and the width of the left side and the right side of the path is 10-30mm by taking the welding seam as the center.
Further, the tube forming includes: HFW welding, welding speed 24m/min, heat treatment temperature of welding seam 940 ℃, heat treatment temperature of pipe body 700 ℃, cooling to 350 ℃ for water cooling, winding on a roller and integrally testing pressure.
Further, the tube forming further includes: and (5) nondestructive testing of the pipe body and coating of a preservative on the surface of the pipe body.
The invention has the beneficial effects that:
the invention provides a dumbbell-shaped coiled pipe coiled plate structural design, the wall thickness of the front section and the rear section of the coiled plate is increased, enough allowance can be reserved for coping and finishing butt welds of the plates, the wall thickness of the butt joint position of the final plates is not smaller than that of a base material, and the bending fatigue resistance of the position of the oblique weld after the pipe is manufactured is improved through the increase of the wall thickness of the butt joint position.
The invention provides a dumbbell-shaped coiled pipe coiled plate structural design, the middle section of the coiled plate is designed with equal wall thickness, the length of the coiled plate is 75% -85% of the total length of the coiled plate, the coiled pipe produced by adopting the coiled plate can meet the requirements of relevant detection standards of the coiled pipe such as an API Spec 5ST standard, a GB/T34204-2017 standard and the like, meanwhile, the weight of the whole coiled pipe product is not obviously increased, and the transportation of the product under complex road conditions is not influenced.
The invention provides a dumbbell-shaped coiled continuous pipe coiled plate structural design, the wall thickness between the middle section and the front section and the rear section of the coiled continuous pipe adopts a slow and smooth transition design, which is beneficial to the design of rolling mill programs in the production process of a steel mill, accords with the capability of the coiled continuous pipe rolling technology of the steel mill, can prevent stress concentration caused by abrupt change of the wall thickness of the coiled continuous pipe, and ensures high quality and bending fatigue resistance of the whole coiled continuous pipe coiled plate.
The invention provides the ultra-fast cooling and thermal deformation treatment of the butt welding seam of the steel belt, which can effectively improve the as-cast structure of the butt welding seam, refine grains, reduce the residual stress of the welding seam, improve the plasticity and toughness of the welding seam, enable the structure to be similar to the parent metal, and improve the bending fatigue resistance of the butt welding seam after the pipe is manufactured.
The invention provides laser shock strengthening treatment for the butt welding seam of the steel belt, wherein the laser shock strengthening treatment can improve the hardness distribution of the welding seam area, so that the hardness distribution of the welding seam area is more uniform, a welding softening area is effectively eliminated, and meanwhile, the inner surface layer of the welding seam generates corresponding plastic deformation in the depth direction, and fatigue crack initiation is effectively inhibited, so that the bending fatigue resistance of the butt welding seam position after pipe making is improved.
According to the invention, through the increase of the wall thickness of the butt joint position and the optimization of the structure and performance of the butt joint weld, the bending fatigue resistance of the circumferential butt joint weld after pipe making is greatly improved to more than 100% of the service life of a main pipe, the method is suitable for manufacturing low-carbon microalloy continuous pipes, the safety of pipe field operation is ensured, and the quality improvement and synergy of an assisted oil field are realized.
Drawings
FIG. 1 is a schematic illustration of a conventional coiled tubing butt joint process, after service, with a leak at the circumferential butt weld, resulting in a complete disc of coiled tubing failure;
FIG. 2 shows a design of the shape of a dumbbell-shaped rolled plate, wherein the wall thickness of the front section and the rear section of the rolled plate is thickened along the two sides of the horizontal center line of the middle section;
FIG. 3 is a view showing another design of the shape of a dumbbell-shaped coiled plate, wherein the wall thickness of the front section and the rear section of the coiled plate is thickened along one side of the horizontal center line of the middle section, and a steel belt is bent upwards when the coiled plate is manufactured;
FIG. 4 is a view showing another design of the shape of a dumbbell-shaped coiled plate, wherein the wall thickness of the front and rear sections of the coiled plate is thickened along one side of the horizontal center line of the middle section, and a steel belt is bent downwards during pipe making;
FIG. 5 shows the structure of the steel strip after oblique welding butt joint, wherein after the steel strip is manufactured, the butt joint position of the steel strip is used for obtaining a continuous pipe with the outer diameter and the inner diameter changed;
FIG. 6 shows a structure after butt welding of steel strips, wherein after pipe making, the butt welding position of the steel strips is changed to obtain a continuous pipe with unchanged outer diameter and changed inner diameter.
FIG. 7 shows a structure after butt welding of steel strips, wherein after pipe making, the butt welding position of the steel strips is provided with a continuous pipe with a constant outer diameter and an invariable inner diameter;
FIG. 8 is a schematic view of a laser shock peening process for butt welds of steel strips according to the present invention;
fig. 9 is a schematic view of a laser impact area, wherein the arrowed lines indicate a spot path during laser impact and the circles indicate spot diameters.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, but are not limited thereto. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Description of the technical terms involved: TIG (Tungsten Inert Gas) is an english abbreviation for non-consumable electrode gas-shielded arc welding. The arc welding method uses pure tungsten or activated tungsten (thorium tungsten, cerium tungsten, zirconium tungsten, lanthanum tungsten) as inert gas for protecting the electrode.
Medium frequency induction heating mode: the inductor is used for inputting medium-frequency alternating current of 500 Hz-20 kHz, and the induction current is used for heating the workpiece by using the skin effect that the surface of the workpiece is strong and the inside is weak.
HFW is high frequency welding: the skin effect is utilized to concentrate the energy of the high-frequency current of 50 KHz-400 KHz on the surface of the workpiece; and the proximity effect is utilized to control the position and the range of the high-frequency current flow path. The current flow is rapid, and it can heat and melt the adjacent edges of the steel plates in a short time, and achieve butt joint by extrusion.
YAG is a shorthand for Neodymium-dopedYttrimum aluminum gas.
Example 1
The invention provides a process method for improving bending fatigue resistance of a continuous pipe, which comprises the following steps:
step 1) design of a coiled plate structure: the coiled plate structure is a dumbbell-shaped coiled plate;
step 2) manufacturing a dumbbell-shaped coiled plate: the method comprises the following steps: smelting, continuous casting into a blank, heating a casting blank, rough rolling, finish rolling, controlled cooling and curling;
step 3) plate bending longitudinal shearing and plate butt welding: cutting the dumbbell-shaped coiled plate into a plurality of steel strips with equal width through a slitting machine set, connecting the plurality of steel strips end to end, and splicing the plurality of steel strips into a length required by a continuous pipe in a plate-to-plate welding mode;
step 4) carrying out heat deformation treatment on the butt welding seam of the steel belt;
step 5), carrying out laser shock reinforcement treatment on the butt welding seams of the steel strips;
step 6), grinding, finishing and nondestructive testing are carried out on the welding seam area to obtain continuous strip steel;
and 7) forming and welding the continuous strip steel to form a tube to obtain the continuous tube with bending fatigue resistance.
Example 2
The invention provides a process method for improving bending fatigue resistance of a continuous pipe, which comprises the following steps:
step 1) design of a coiled plate structure: the coiled plate structure is a dumbbell-shaped coiled plate;
further, as shown in fig. 2-4, the dumbbell-shaped rolled plate is divided into a front section, a middle section and a rear section along the length direction of the rolled plate, the thickness of the front section and the rear section is equal, the thickness of the front section and the thickness of the rear section are larger than the thickness of the middle section, and the middle section is connected with the front section and the rear section through a smooth transition section;
the preparation method specifically comprises the following two forms:
as shown in fig. 2, in the first embodiment, the thicknesses of the front section and the rear section are symmetrical on two sides with the horizontal center line of the middle section as a reference; as shown in fig. 5, the coiled steel strip is cut into steel strips in the width direction, and after the steel strips are manufactured into pipes, a continuous pipe with the outer diameter and the inner diameter changing is obtained;
as shown in fig. 3 and 4, the bottom surfaces of the front section, the middle section and the rear section are all on the same plane, and the upper surfaces of the front section and the rear section are higher than the middle section; as shown in fig. 6, the coiled steel strip is bent upwards to form a tube, and the outer diameter of the coiled steel strip is unchanged, and the inner diameter of the coiled steel strip is changed; as shown in fig. 7, or a steel strip is bent downward to form a continuous pipe with a constant inner diameter and a variable outer diameter.
Further, the wall thickness t of the middle section 1 Length L 1 Length of the segment L 1 Accounting for 75-85% of the whole length of the coiled plate, and the front and rear sections have equal wall thickness and equal length, and the wall thickness t 2 Length L 2 Length of the segment L 2 4-6% of the total length of the coiled plate and the wall thickness t 2 Is the wall thickness t 1 104-124% of (2); the wall thickness and the length of the two smooth transition sections are equal, and the wall thickness t x The thickness is increased linearly from thin to thick, and the length Lx accounts for 4% -6% of the whole length of the coiled plate.
Step 2) manufacturing a dumbbell-shaped coiled plate: the method comprises the following steps: smelting, continuous casting into a blank, heating a casting blank, rough rolling, finish rolling, controlled cooling and curling; the cooling control technology is the prior art and will not be described in detail here.
Step 3) plate bending longitudinal shearing and plate butt welding: cutting the dumbbell-shaped coiled plate into a plurality of steel strips with equal width through a slitting machine set, connecting the plurality of steel strips end to end, and splicing the plurality of steel strips into a length required by a continuous pipe in a plate-to-plate welding mode;
further, the welding mode of the plate to plate is as follows: firstly, the ends of the front steel strip and the rear steel strip are processed into 45 degrees to 60 degrees, then the oblique butt joint is carried out, then the joint is held and fixed by a copper block with circulating water inside, and finally, the welding is carried out by adopting a TIG welding, filling welding wire or plasma welding and filling welding wire process (such as oblique welding lines in fig. 5 to 7).
Step 4) heat deformation treatment of the steel strip butt weld: adopting an intermediate frequency induction heating mode to rapidly heat the welding seam to 840-1000 ℃ for the first time, stopping heating, and applying 3-12 tons of rolling force or forging force perpendicular to the welding seam direction to further refine the welding seam structure; and then the welding seam is air-cooled to below 150 ℃, the welding seam is heated for the second time by adopting medium frequency induction, the heating temperature is 500-780 ℃, and the welding seam is naturally cooled, so that the residual stress caused by welding and thermal deformation is eliminated, and the hardness of the welding seam is improved.
Step 5) laser shock reinforcement treatment of the steel strip butt weld: removing the surplus height of the weld seam, and moving the butt weld seam to a laser reinforced numerical control workbench for laser impact treatment;
YAG laser is used as a transmitting source, pulse laser energy is 3-22J, impact frequency is 1Hz, wavelength is 1064nm, pulse width is 10ns, spot diameter is 4mm, and lap joint rate of light spots is 33.3%; as shown in fig. 8, aluminum foil was used as the absorbing layer, with a thickness of 0.1mm; taking the uniform flowing water film as a constraint layer, wherein the thickness is 1.8-2.2mm; the laser beam and the surface of the welding seam are always kept vertical in the laser impact process, and stress waves are generated on the target (steel belt); as shown in fig. 9, the spot path: the path length is the length of the oblique welding seam, and the width of the left side and the right side of the path is 10-30mm by taking the welding seam as the center.
And 6) after the butt welding seam is subjected to laser shock reinforcement treatment, grinding, finishing and nondestructive testing are carried out on the welding seam area, and the continuous strip steel is obtained.
And 7) forming and welding the continuous strip steel to form a tube to obtain the continuous tube with bending fatigue resistance.
Further, the pipe forming specifically includes: HFW welding, welding speed 24m/min, heat treatment temperature of welding seam 940 ℃, heat treatment temperature of pipe body 700 ℃, cooling to 350 ℃ for water cooling, winding on a roller, and integrally testing pressure, and obtaining the continuous pipe with required length and improved bending fatigue resistance. The tube forming step further includes: after the heat treatment and cooling of the pipe body, the pipe body is subjected to nondestructive testing and the surface is coated with a preservative.
Example 3
The embodiment is an application example, and the method is adopted to prepare a continuous pipe with bending fatigue resistance, CT80 steel grade specification and phi 38.1 multiplied by 3.4mm, and the specific steps are as follows:
the coiled plate adopts a coiled plate shape design with a dumbbell-shaped structure.
Further, the shape of the dumbbell-shaped coiled plate is that the front wall thickness and the rear wall thickness of the coiled plate are thickened along the two sides of the horizontal central line of the middle section (shown in fig. 2), and after the steel strip is manufactured into a tube, a continuous tube with the outer diameter and the inner diameter changing is obtained (shown in fig. 5).
The invention also provides a processing method of the dumbbell-structured rolled plate, which comprises the following steps of:
(1) Design of dumbbell-structured coiled plate
The middle section of the coiled plate in the length direction is designed with equal wall thickness, the wall thickness of the section is 3.4mm, and the length is 530 meters; the front section and the rear section are designed in a thickening way, the wall thickness of the section is 3.74mm, and the length is 30 meters; the thickened section and the equal wall thickness section are in slow and smooth transition, the wall thickness is increased linearly, and the length is 30 meters.
(2) Preparation of dumbbell-structured coiled plate
The coil comprises the following chemical components in percentage by mass:
c:0.08%; si:0.20%; mn:0.80%; p:0.01%; s:0.003%; cu:0.28%; cr:0.50%; ni:0.20%; mo:0.3%; ti:0.015%; nb:0.03% of Fe and the balance of unavoidable impurities.
The preparation process of the coiled plate comprises the following steps:
molten iron is pre-desulfurized, smelted, alloy-regulated, treated by LF+RH and Ca, continuously cast into a slab with the thickness of 100mm, heated to 1200 ℃ for rough rolling, finish rolled into a hot rolled plate with the front and rear wall thickness of 3.74mm and the middle wall thickness of 3.4mm according to the design requirement of a dumbbell-shaped structure, coiled at the temperature of about 500-600 ℃ and subjected to pickling, finishing and curling for pipe production.
Further, the coiled plate is longitudinally sheared and the plate is butt welded. And shearing the prepared coiled plate into a 130mm steel strip through a slitting machine set. The ends of the front steel strip and the rear steel strip are processed into 45 degrees and then are spliced, a copper block with circulating water inside is used for holding and fixing the spliced position, the circulating water inside the copper block is opened for ultra-fast cooling treatment, and a plasma welding and ER80S welding wire process is adopted for welding.
Further, the butt welding seam of the steel belt is subjected to heat deformation treatment. And (3) rapidly heating the welding seam to 900 ℃ by adopting medium-frequency induction heating, carrying out hot rolling on the welding seam after the heating temperature is reached, wherein the rolling force is 4 tons, cooling the welding seam to below 150 ℃ after rolling, heating the welding seam to 660 ℃ again, and naturally cooling.
Further, the laser shock strengthening treatment of the butt welding line of the steel belt. And removing the surplus height of the welding seam, and moving the butt welding seam to a laser reinforced numerical control workbench. YAG laser is selected as a transmitting source, the pulse laser energy is 7.5J, the impact frequency is 1Hz, the wavelength is 1064nm, the pulse width is 10ns, the diameter of a light spot is 4mm, and the lap joint rate of the light spot is 33.3%. The aluminum foil is used as an absorption layer, and the thickness is 0.1mm; the uniform flow water film was used as a constraining layer and had a thickness of about 2mm. In the laser impact process, the laser beam and the surface of the welding line are always vertical, and the light spot path is: the path length is the length of the oblique welding seam, and the width of the left side and the right side of the path is 15mm by taking the welding seam as the center. And after the butt welding seam is subjected to laser shock strengthening treatment, repairing and grinding, finishing and nondestructive testing are carried out on the welding seam area.
Further, the head and tail of the multi-section steel belt are welded to form continuous steel belt, the continuous shaping of the steel belt is carried out, the HFW welding is carried out, the welding speed is 28m/min, the heat treatment temperature of the welding seam is 900 ℃, the heat treatment temperature of the pipe body is 750 ℃, the cooling temperature is 300 ℃ and the water cooling is carried out, the pipe body is wound on a roller, and the whole pressure test is qualified, thus obtaining the steel grade CT80 steel with bending fatigue resistance performance and specification,Is a continuous tube of (a).
The invention has bending fatigue resistance and specification of CT80 steel grade,Is the main of the continuous pipe of (2)The main mechanical properties and bending fatigue resistance of the product are as follows:
TABLE 1 detection results of major mechanical Properties
TABLE 2 comparison of flexural fatigue resistance
Example 4
The embodiment is another application example, and the embodiment adopts the process method of the invention to prepare the steel grade CT110 steel with bending fatigue resistance,The specific steps are as follows:
the plate adopts a dumbbell-shaped structure coiled plate shape design.
Further, the shape of the dumbbell-shaped structure coiled plate is that the wall thickness of the front wall and the rear wall of the coiled plate is thickened along one side of the inner wall of the horizontal center line of the middle section (shown in figure 3), and a continuous pipe with the unchanged outer diameter and the changed inner diameter is obtained at the butt joint position of the steel strip after the pipe is manufactured (shown in figure 6).
The invention also provides a processing method of the dumbbell-structured rolled plate, which comprises the following steps of:
(1) Design of dumbbell-structured coiled plate
The middle section of the coiled plate in the length direction is designed with equal wall thickness, the wall thickness of the section is 4.44mm, and the length is 410 meters; the front section and the rear section are designed in a thickening way, the wall thickness of the section is 4.84mm, and the length is 25 meters; the thickened section and the equal wall thickness section are in slow and smooth transition, the wall thickness is increased linearly, and the length is 25 meters.
(2) Preparation of dumbbell-structured coiled plate
The coil comprises the following chemical components in percentage by mass:
c:0.12%; si:0.23%; mn:1.4%; p:0.005%; s:0.004%; cu:0.23%; cr:0.60%; ni:0.14%; mo:0.13%; ti:0.02%; nb:0.03% of Fe and the balance of unavoidable impurities.
The preparation process of the coiled plate comprises the following steps:
molten iron is pre-desulfurized, smelted, alloy-regulated, treated by LF+RH and Ca, continuously cast into a slab with the thickness of 100mm, heated to 1200 ℃ for rough rolling, finish rolled into a hot rolled plate with the front and rear wall thickness of 4.84mm and the middle wall thickness of 4.44mm according to the design requirement of a dumbbell-shaped structure, coiled at the temperature of about 500-600 ℃ and subjected to pickling, finishing and curling for pipe production.
Further, the coiled plate is longitudinally sheared and the plate is butt welded. And shearing the prepared coiled plate into a 159.6mm steel belt through a slitting machine set. The ends of the front steel strip and the rear steel strip are processed into 45 degrees and then are spliced, a copper block with circulating water inside is used for holding and fixing the spliced position, the circulating water inside the copper block is opened for ultra-fast cooling treatment, and a plasma welding and ER110S welding wire process is adopted for welding.
Further, the steel strip butt weld is subjected to thermal deformation. And rapidly heating the welding seam to 980 ℃ by adopting medium-frequency induction heating, carrying out hot rolling on the welding seam after the heating temperature is reached, wherein the rolling force is 9 tons, cooling the welding seam to below 150 ℃ after rolling, heating the welding seam to 600 ℃ again, and naturally cooling.
Further, the laser shock strengthening treatment of the butt welding line of the steel belt. And removing the surplus height of the welding seam, and moving the butt welding seam to a laser reinforced numerical control workbench. YAG laser is selected as a transmitting source, the pulse laser energy is 9J, the impact frequency is 1Hz, the wavelength is 1064nm, the pulse width is 10ns, the diameter of a light spot is 4mm, and the lap joint rate of the light spot is 33.3%. The aluminum foil is used as an absorption layer, and the thickness is 0.1mm; the uniform flow water film was used as a constraining layer and had a thickness of about 2mm. In the laser impact process, the laser beam and the surface of the welding line are always vertical, and the light spot path is: the path length is the length of the oblique welding seam, and the width of the path is 25mm from left to right with the welding seam as the center. And after the butt welding seam is subjected to laser shock strengthening treatment, repairing and grinding, finishing and nondestructive testing are carried out on the welding seam area.
Further, the head and tail of the multi-section steel belt are welded to form continuous steel belt, the continuous molding of the steel belt and HFW welding are carried out, the welding speed is 24m/min,the heat treatment temperature of the welding seam is 940 ℃, the heat treatment temperature of the pipe body is 700 ℃, the pipe body is cooled to 350 ℃ for water cooling, and the pipe body is wound on a roller, and the whole pressure test is qualified, so that the pipe body has bending fatigue resistance and has the specification of CT110 steel grade,Is a continuous tube of (a).
The main performance test is carried out on the continuous pipe with bending fatigue resistance and specification of CT 110-phi 50.8x4.44 mm, and the main mechanical properties and bending fatigue resistance are as follows:
TABLE 3 detection results of major mechanical Properties
TABLE 4 comparison of flexural fatigue resistance
Therefore, the continuous pipe with bending fatigue resistance produced by the process method not only produces a conventional continuous pipe product meeting the API standard requirement, but also has bending fatigue resistance superior to that of the conventional continuous pipe, and is suitable for manufacturing the low-carbon microalloy continuous pipe.
The coiled plate manufactured by the coiled pipe adopts a dumbbell-shaped structural design, namely, the middle section of the coiled plate along the length direction is designed with equal wall thickness, and the wall thickness of the front section and the rear section of the coiled plate is designed with thickening, so that the wall thickness of the butt joint position of the steel belt and the steel belt is increased compared with the wall thickness of the pipe body. And the welding joint adopts the composite treatment of ultra-fast cooling, thermal deformation and laser shock reinforcement, improves the microstructure of the welding seam, optimizes the hardness of the welding seam, prevents the softened region of the welding seam from being present, and realizes the integral quality improvement of the butt welding seam of the steel belt.
The foregoing is a further detailed description of the present invention in connection with the preferred embodiments, and it is not intended to limit the embodiments of the invention to the precise forms set forth herein, but rather to enable one skilled in the art to make various simple inferences, substitutions or alternations without departing from the spirit of the invention, which is intended to be interpreted as falling within the scope of the appended claims. The components and structures not specifically described in this embodiment are well known in the art and are not described in detail herein.
Claims (10)
1. A process method for improving bending fatigue resistance of a continuous pipe is characterized by comprising the following steps:
and (3) designing a coiled plate structure:
the coiled plate structure is a dumbbell-shaped coiled plate;
manufacturing a dumbbell-shaped coiled plate:
the method comprises the following steps: smelting, continuous casting into a blank, heating a casting blank, rough rolling, finish rolling, controlled cooling and curling;
plate bending longitudinal shearing and plate butt welding;
cutting the dumbbell-shaped coiled plate into a plurality of steel strips with equal width through a slitting machine set, connecting the plurality of steel strips end to end, and splicing the plurality of steel strips into a length required by a continuous pipe in a plate-to-plate welding mode;
performing heat deformation treatment on the butt welding seam of the steel belt;
laser shock reinforcement treatment of the butt welding seam of the steel belt;
grinding, finishing and nondestructive testing are carried out on the welding line area to obtain continuous strip steel;
and (3) forming and welding the continuous strip steel to form a tube to obtain the continuous tube with bending fatigue resistance.
2. The process for improving bending fatigue resistance of a coiled pipe according to claim 1, wherein the dumbbell-shaped coiled plate is divided into a front section, a middle section and a rear section along the length direction of the coiled plate, the thickness of the front section coiled plate and the thickness of the rear section coiled plate are equal, the thickness of the front section coiled plate is larger than the thickness of the middle section, and the middle section is connected with the front section and the rear section through a smooth transition section;
the preparation method specifically comprises the following two forms:
firstly, the thicknesses of the front section and the rear section are symmetrical on two sides by taking the horizontal central line of the middle section as a reference; the coiled steel strip is cut into steel strips along the width direction, and after the steel strips are manufactured into tubes, a continuous tube with the outer diameter and the inner diameter changing is obtained;
second, the bottom surfaces of the front section, the middle section and the rear section are all on the same plane, and the upper surfaces of the front section and the rear section are higher than the middle section; the coiled steel strip is bent upwards to form a tube so as to obtain a continuous tube with unchanged outer diameter and changeable inner diameter; or bending the steel belt downwards to form a tube to obtain a continuous tube with the outer diameter being changed and the inner diameter being unchanged.
3. The process for improving bending fatigue resistance of a coiled tubing according to claim 2, wherein the length of the middle section is 75% -85% of the total length of the coiled tubing, the front and rear sections are 4% -6% of the total length of the coiled tubing, the two smooth transition sections are 4% -6% of the total length of the coiled tubing, and the thickness of the front and rear sections is 104% -124% of the thickness of the middle section.
4. The process for improving bending fatigue resistance of a coiled pipe according to claim 1, wherein the coiled pipe comprises the following chemical components in percentage by mass:
c:0.08%; si:0.20%; mn:0.80%; p:0.01%; s:0.003%; cu:0.28%; cr:0.50%; ni:0.20%; mo:0.3%; ti:0.015%; nb:0.03% of Fe and the balance of unavoidable impurities;
or is:
c:0.12%; si:0.23%; mn:1.4%; p:0.005%; s:0.004%; cu:0.23%; cr:0.60%; ni:0.14%; mo:0.13%; ti:0.02%; nb:0.03% of Fe and the balance of unavoidable impurities.
5. The process for improving bending fatigue resistance of a continuous tube according to claim 1, wherein the plate-to-plate welding method is as follows: firstly, the ends of the front steel belt and the rear steel belt are processed into 45 degrees to 60 degrees, then the oblique butt joint is carried out, then the splice is held and fixed through a copper block with circulating water inside, and finally, the TIG welding, the filler wire or the plasma welding and the filler wire technology are adopted for welding.
6. The process for improving bending fatigue resistance of a continuous tube according to claim 1, wherein the heat deformation treatment of the steel strip butt weld: adopting an intermediate frequency induction heating mode to rapidly heat the welding seam to 840-1000 ℃ for the first time, stopping heating, and applying 3-12 tons of rolling force or forging force perpendicular to the welding seam direction to further refine the welding seam structure; and then the welding seam is air-cooled to below 150 ℃, the welding seam is heated for the second time by adopting medium frequency induction, the heating temperature is 500-780 ℃, and the welding seam is naturally cooled, so that the residual stress caused by welding and thermal deformation is eliminated, and the hardness of the welding seam is improved.
7. The process for improving bending fatigue resistance of a continuous tube according to claim 1, wherein the steel strip butt weld laser shock peening is characterized by: and removing the surplus height of the weld seam, and moving the butt weld seam to a laser reinforced numerical control workbench for laser impact treatment.
8. The process method for improving bending fatigue resistance of the continuous tube according to claim 1, wherein the laser strengthening numerical control workbench is characterized in that an Nd-YAG laser is used as a transmitting source, the pulse laser energy is 3-22J, the impact frequency is 1Hz, the wavelength is 1064nm, the pulse width is 10ns, the diameter of a light spot is 4mm, and the lap joint rate of the light spot is 33.3%; the aluminum foil is used as an absorption layer, and the thickness is 0.1mm; taking the uniform flowing water film as a constraint layer, wherein the thickness is 1.8-2.2mm; the laser beam and the surface of the welding line are always kept vertical in the laser impact process; spot path: the path length is the length of the oblique welding seam, and the width of the left side and the right side of the path is 10-30mm by taking the welding seam as the center.
9. The process for improving bending fatigue resistance of a continuous tube as set forth in claim 1, wherein said tube forming comprises: HFW welding, welding speed 24m/min, heat treatment temperature of welding seam 940 ℃, heat treatment temperature of pipe body 700 ℃, cooling to 350 ℃ for water cooling, winding on a roller and integrally testing pressure.
10. The process for improving bending fatigue resistance of a coiled tubing according to claim 9, further comprising: and (5) nondestructive testing of the pipe body and coating of a preservative on the surface of the pipe body.
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