CN116728002A - Preparation method of low-carbon microalloy ultrahigh-strength continuous pipe - Google Patents
Preparation method of low-carbon microalloy ultrahigh-strength continuous pipe Download PDFInfo
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- CN116728002A CN116728002A CN202210198929.4A CN202210198929A CN116728002A CN 116728002 A CN116728002 A CN 116728002A CN 202210198929 A CN202210198929 A CN 202210198929A CN 116728002 A CN116728002 A CN 116728002A
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- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 25
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 238000010438 heat treatment Methods 0.000 claims abstract description 128
- 238000003466 welding Methods 0.000 claims abstract description 113
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 77
- 239000010959 steel Substances 0.000 claims abstract description 77
- 238000000034 method Methods 0.000 claims abstract description 49
- 238000004519 manufacturing process Methods 0.000 claims abstract description 14
- 238000010008 shearing Methods 0.000 claims abstract description 14
- 238000000465 moulding Methods 0.000 claims abstract description 3
- 238000001816 cooling Methods 0.000 claims description 54
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 28
- 230000006698 induction Effects 0.000 claims description 27
- 239000002994 raw material Substances 0.000 claims description 19
- 229910045601 alloy Inorganic materials 0.000 claims description 17
- 239000000956 alloy Substances 0.000 claims description 17
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 13
- 238000004321 preservation Methods 0.000 claims description 11
- 230000009466 transformation Effects 0.000 claims description 11
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 9
- 238000004513 sizing Methods 0.000 claims description 9
- 238000005096 rolling process Methods 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 8
- 238000000861 blow drying Methods 0.000 claims description 6
- 238000002788 crimping Methods 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 5
- 238000005496 tempering Methods 0.000 claims description 5
- 238000005098 hot rolling Methods 0.000 claims description 4
- 238000005554 pickling Methods 0.000 claims description 4
- 238000004804 winding Methods 0.000 claims description 4
- 239000000498 cooling water Substances 0.000 claims description 3
- 238000001514 detection method Methods 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 229910001562 pearlite Inorganic materials 0.000 claims description 3
- 238000005498 polishing Methods 0.000 claims description 3
- 239000007921 spray Substances 0.000 claims description 3
- 239000002352 surface water Substances 0.000 claims description 3
- 230000006032 tissue transformation Effects 0.000 claims description 3
- 230000007704 transition Effects 0.000 claims description 3
- 229910000859 α-Fe Inorganic materials 0.000 claims description 3
- 229910001873 dinitrogen Inorganic materials 0.000 claims 1
- 239000010953 base metal Substances 0.000 abstract description 2
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 230000008520 organization Effects 0.000 abstract 1
- 238000005516 engineering process Methods 0.000 description 8
- 238000005452 bending Methods 0.000 description 6
- 229910052757 nitrogen Inorganic materials 0.000 description 6
- 239000008186 active pharmaceutical agent Substances 0.000 description 5
- 238000001125 extrusion Methods 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 230000007547 defect Effects 0.000 description 4
- 229910000734 martensite Inorganic materials 0.000 description 4
- 238000003801 milling Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000005242 forging Methods 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 229910001339 C alloy Inorganic materials 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
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- 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
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- 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
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Abstract
The invention discloses a preparation method of a low-carbon microalloy ultrahigh-strength continuous pipe, which is implemented according to the following steps: step 1, preparing a coiled plate; step 2, longitudinal shearing of the coiled plate and lengthening of the steel belt; step 3, molding and welding; and 4, offline heat treatment. The invention realizes the uniformity and unification of the weld joint and the base metal in the aspects of organization and performance through off-line heat treatment, avoids the influence of the steel strip oblique weld joint and the continuous pipe straight weld joint on the performance of the continuous pipe, greatly prolongs the whole service life of the continuous pipe, has simple and convenient preparation process and operation, is beneficial to improving the preparation efficiency, and solves the problems of high production difficulty and low efficiency in the process of preparing the continuous pipe with high strength and high fatigue life in the prior art.
Description
Technical Field
The invention belongs to the technical field of continuous tube preparation, and particularly relates to a preparation method of a low-carbon micro-alloy ultrahigh-strength continuous tube.
Background
The coiled tubing is also called as coiled tubing, is a novel oil-gas tubing with high strength and good plasticity, and has the advantages of low operation cost, simplicity, time saving, safety, reliability and the like compared with the common tubing, so that the coiled tubing is widely applied to the fields of sand flushing, well logging, well completion, well drilling and the like, and the coiled tubing technology plays an increasingly important role in oil-gas field exploration, development, operation and yield increase.
With the increasing difficulty of oil gas exploration and development in China and the increasing quantity of unconventional oil gas resource development such as shale gas, the requirements of deep well and ultra-deep well operation on the performances such as strength, fatigue and the like of continuous pipes are increasingly increased. The continuous tube technology is developed to date, the conventional low-carbon alloy steel tube is mainly used, the conventional continuous tube performs on-line normalizing treatment on the tube body in the tube manufacturing process, and on-line heat treatment has limited effect on improving the performance of the continuous tube. In recent years, although the development of steel smelting technology is advanced, the performance of continuous pipes is improved to a certain extent, and the continuous pipes are still difficult to prepare by means of strengthening modes such as alloying, rolling, cooling and the like due to the limitation of factors such as the strength of forming rollers of pipe-restraining equipment, and the extrusion damage of rollers can occur in the pipe-making process, so that the production of the continuous pipes cannot be normally carried out, and the production efficiency of the high-strength continuous pipes is affected.
Disclosure of Invention
The invention aims to provide a preparation method of a low-carbon microalloy ultrahigh-strength continuous pipe, which solves the problems of high production difficulty and low efficiency in the process of preparing a high-strength and high-fatigue-life continuous pipe in the prior art.
The technical scheme adopted by the invention is that the preparation method of the low-carbon microalloy ultrahigh-strength continuous pipe is implemented according to the following steps:
step 1, preparing a coiled plate;
step 2, longitudinal shearing of the coiled plate and lengthening of the steel belt;
step 3, molding and welding;
and 4, offline heat treatment.
The present invention is also characterized in that,
shearing the coiled plate prepared in the step 1 into steel strips with corresponding widths through a slitting machine set according to the specification requirement of a continuous pipe, obliquely cutting the end parts of the front steel strip and the rear steel strip into 45 degrees, processing an I-shaped groove, and performing assembly welding by adopting an argon arc welding or plasma arc welding method; and (5) polishing after welding to remove the surplus height of the weld seam, and performing post-welding rolling deformation heat treatment on the oblique weld seam.
And 2, during heat treatment, the welding line is quickly heated to 960 ℃, is thermally rolled or forged, is naturally cooled to below 200 ℃, is quickly heated to 600 ℃, is naturally cooled to room temperature, and is polished and cleaned after being cooled.
And step 2, the steel strip is curled and formed by a forming unit, a welding squeeze roller is adjusted, the edges of the curled steel strip are tightly attached and have no offset phenomenon, straight seam welding is carried out by adopting a high-frequency induction welding method, welding seams are subjected to heat treatment by adopting an intermediate-frequency induction heating mode after welding, sizing treatment is carried out, the outer diameter of the required continuous pipe is obtained, and the continuous pipe is wound on a winding drum with corresponding specification.
And 3, heating the welding seam to 900-960 ℃ during heat treatment of the welding seam, and cooling to below 400 ℃ under the protection of nitrogen for water cooling.
And (3) re-opening the coiled continuous pipe in the step (3) through a heat treatment unit, and performing whole pipe heat treatment, wherein the whole pipe heat treatment process comprises three links, namely primary heat treatment, blow-drying and secondary heat treatment.
The specific process of the step 4 is as follows: when in primary heat treatment, a plurality of groups of medium-frequency heating furnaces are adopted to perform full-tube induction heating, the continuous tube body is heated to 1000-1050 ℃, after the heating is completed, the continuous tube body rapidly enters a cooling water system to be cooled, the flow and the pressure of the water are determined by the wall thickness of the continuous tube and the tube making speed, the tube wall is ensured to be rapidly cooled to be below the phase transition point temperature, and the tissue transformation is completed;
and (3) rapidly removing residual moisture in the surface water cooling process of the continuous tube by using compressed air, performing secondary heat treatment, combining and using a plurality of groups of medium-frequency induction heating furnaces, heating to 650-700 ℃, ensuring sufficient heating and heat preservation effective length, manufacturing a movable track by using the last group of medium-frequency induction heating furnaces, moving back and forth according to different temperatures in winter and summer, ensuring that the temperature before entering the heating furnaces is not lower than 600 ℃, finishing tempering structure transformation, cooling to below 450 ℃ by air cooling, cooling to room temperature by using a spray water tank, finishing the whole tube heat treatment process, and finally coiling the whole tube heat treated continuous tube by using a crimping machine to obtain the ultrahigh-strength continuous tube with the required length.
In the step 1, plate raw materials are selected according to a proportion, molten iron is used as a main raw material, alloy elements are added into the raw materials, a steel coil is hot rolled to obtain a ferrite and pearlite blending balance structure, and after pickling, finishing and detection, the steel coil is curled into a coiled plate by a tension curling machine for pipe making.
The chemical components in the plate raw materials of the continuous pipe in the step 1 are as follows in percentage by mass: 0.17-0.30% of C, 0.12-0.50% of Si, 0.60-1.8% of Mn, less than or equal to 0.02% of P, less than or equal to 0.003% of S, and the balance of Fe and unavoidable impurities.
Any one or more alloy elements in Cr, ni, cu, ti, nb, mo are also included in the raw materials in the step 1, and the total amount of the alloy elements is not more than 5.0%.
The beneficial effects of the invention are as follows: according to the preparation method of the low-carbon microalloy ultrahigh-strength continuous pipe, after the continuous pipe is manufactured, the offline heat treatment is performed through the process flows of uncoiling, straightening, traction, hot water cleaning, primary heat treatment, water cooling, blow drying, secondary heat treatment, air cooling, water cooling, sizing, inspection, winding and the like, and the probability of failure caused by production faults is reduced through the tempering heat treatment of the continuous pipe, so that the yield is improved, and the tissue performance is improved. The continuous pipe prepared by the invention has ultrahigh strength and high fatigue life, meets the requirements of deep wells and ultra-deep wells on the bearing capacity performance of the continuous pipe, has uniform and consistent weld joint, parent metal structure and performance, has simple production and preparation process and high efficiency, and is suitable for wide popularization in industrial production.
Drawings
FIG. 1 is a flow chart of a method of making a low carbon microalloyed ultrahigh strength continuous tube of the invention;
FIG. 2 is a flow chart of an off-line heat treatment of a method for preparing a low carbon microalloyed ultrahigh strength continuous tube in accordance with the invention.
Detailed Description
The invention will be described in detail below with reference to the drawings and the detailed description.
The preparation method of the low-carbon microalloy ultrahigh-strength continuous pipe, as shown in figure 1, is implemented specifically according to the following steps:
step 1, preparing a coiled plate
Selecting plate raw materials according to a proportion, taking molten iron as a main raw material, adding alloy elements into the raw materials, hot-rolling to enable a steel coil to obtain a ferrite and pearlite blending balance structure, pickling, finishing, detecting, and curling into a coiled plate by a tension curling machine for pipe making;
the chemical components in the plate raw materials of the continuous pipe are as follows by mass percent: 0.17-0.30% of C, 0.12-0.50% of Si, 0.60-1.8% of Mn, less than or equal to 0.02% of P, less than or equal to 0.003% of S, and the balance of Fe and unavoidable impurities. In order to improve the heat treatment manufacturability, the raw materials also comprise any one or more alloy elements in Cr, ni, cu, ti, nb, mo, and the total amount of the alloy elements is not more than 5.0 percent.
Step 2, plate bending longitudinal shearing and steel strip lengthening
Shearing the coiled plate prepared in the step 1 into steel strips with corresponding widths through a slitting machine set according to the specification requirement of a continuous pipe, obliquely cutting the end parts of the front steel strip and the rear steel strip into 45 degrees, processing an I-shaped groove, and performing assembly welding by adopting an argon arc welding or plasma arc welding method; polishing after welding to remove the surplus height of the weld seam, and performing post-welding rolling deformation heat treatment on the oblique weld seam to optimize the performance; and during heat treatment, the welding line is quickly heated to 960 ℃, is thermally rolled or forged, is naturally cooled to below 200 ℃, is quickly heated to 600 ℃, is naturally cooled to room temperature, and is polished and cleaned after being cooled.
Step 3, forming and welding
The steel strip is curled and formed by a forming unit, a welding squeeze roller is adjusted, the edges of the curled steel strip are tightly attached and have no offset phenomenon, straight seam welding is carried out by adopting a high frequency induction welding method (HFW), a welding seam is subjected to heat treatment by adopting an intermediate frequency induction heating mode after welding, when the welding seam is subjected to heat treatment, the welding seam is heated to 900-960 ℃, cooled to below 400 ℃ under the protection of nitrogen, water cooling is carried out, sizing treatment is carried out, the outer diameter size of a required continuous pipe is obtained, and the continuous pipe is wound on a winding drum with corresponding specification;
step 4, off-line heat treatment
And re-opening the coiled continuous pipe through a heat treatment unit, and performing whole pipe body tempering heat treatment, wherein the whole pipe body heat treatment process comprises three links, namely primary heat treatment, blow-drying and secondary heat treatment.
As shown in fig. 2, during primary heat treatment, a plurality of groups of medium-frequency heating furnaces are adopted to perform full-tube induction heating, the continuous tube body is heated to 1000-1050 ℃, after the heating is completed, the continuous tube body quickly enters a cooling water system to be cooled by water, the flow and the pressure of the water are determined by the wall thickness of the continuous tube and the tube making speed, the tube wall is ensured to be quickly cooled below the phase transition point temperature, and the tissue transformation is completed; after one-time heat treatment, a continuous pipe with a weld joint and a parent metal structure and uniform performance is obtained.
The welding seam in the primary heat treatment comprises a steel belt oblique welding seam and a continuous pipe straight welding seam, and the carbide in the subsequent secondary heat treatment structure is uniformly dispersed and separated out, so that the comprehensive mechanical property of the continuous pipe is improved.
And (3) rapidly removing residual moisture in the surface water cooling process of the continuous tube by using compressed air, performing secondary heat treatment, combining and using a plurality of groups of medium-frequency induction heating furnaces, heating to 650-700 ℃, ensuring sufficient heating and heat preservation effective length, manufacturing a movable track by using the last group of medium-frequency induction heating furnaces, moving back and forth according to different temperatures in winter and summer, ensuring that the temperature before entering the heating furnaces is not lower than 600 ℃, finishing tempering structure transformation, cooling to below 450 ℃ by air cooling, cooling to room temperature by using a spray water tank, finishing the whole tube heat treatment process, and finally coiling the whole tube heat treated continuous tube by using a crimping machine to obtain the ultrahigh-strength continuous tube with the required length.
Compared with the online heat treatment in the existing continuous pipe manufacturing process, the offline heat treatment method in the step 4 means that the pipe is unreeled, heat treated and wound again after the pipe manufacturing is completed. The heat treatment unit comprises the technological processes of uncoiling, straightening, traction, hot water cleaning, primary heat treatment, water cooling, blow drying, secondary heat treatment, air cooling, water cooling, sizing, inspection, coiling and the like.
Example 1
The preparation of the low-carbon microalloy ultrahigh-strength continuous pipe in the embodiment 1 is carried out according to the following steps;
step 1, preparing a coiled plate
The raw materials of the embodiment are prepared according to the mass percentages of the chemical components in the table 1, hot rolled coils are prepared through a rolling control and cooling control technology, and after pickling, finishing and detection, the hot rolled coils are curled into coils by a tension curling machine for pipe making. Table 2 shows the mechanical properties of the sheet material of this example.
TABLE 1 chemical composition of plate (wt.%)
| C | Si | Mn | P | S | Cr | Ni | Cu | Ti | Nb | Mo | Fe |
| 0.19 | 0.12 | 0.91 | 0.009 | 0.002 | 0.59 | 0.15 | 0.24 | 0.011 | 0.016 | 0.14 | The rest are |
Table 2 mechanical properties of the sheet material
| Steel sample | Yield strength (MPa) | Tensile strength (MPa) | Elongation (%) | Hardness (HRC) |
| Examples | 540 | 708 | 17 | 17 |
Step 2, plate bending longitudinal shearing and steel strip lengthening
Shearing the prepared coiled plate into a 159mm steel belt through a slitting machine set; in order to meet the length requirement of a continuous pipe, the ends of the front steel strip and the rear steel strip are processed into 45-degree bevel edges, I-shaped grooves are formed on the 45-degree bevel edges, butt welding is carried out on the front steel strip bevel edges and the rear steel strip bevel edges by adopting an argon arc welding method, a welding line is quickly heated to 960 ℃, hot rolling or hot forging is carried out, natural cooling is carried out to below 200 ℃, then the temperature is quickly heated to 600 ℃, natural cooling is carried out to room temperature, and the surface of the welding line is polished and cleaned after the welding line is cooled.
Step 3, forming and welding
The side surface of the steel belt is planed into an I-shaped groove by adopting a side milling method, the width of the steel belt and the perpendicularity of the plate edges are accurately controlled, and the steel belt is molded by adopting an extrusion molding method; the formed steel strip is longitudinally welded by adopting a high-frequency induction welding technology, and welding power and welding speed parameters are accurately controlled: the welding power is 130kw, the welding speed is 21m/min, the welding seam is heated to 900 when the welding seam is heat treated, the welding seam is cooled to below 400 ℃ under the protection of nitrogen, then sizing treatment is carried out, the welding seam is ensured to have no defects of air holes and microcracks after welding, and finally the straight seam continuous pipe with the pipe diameter of phi 50.8mm and the wall thickness of 4.44mm is formed by welding.
Step 4, off-line heat treatment
After the forming and welding are finished, the continuous pipe is sequentially subjected to primary heat treatment, blow drying and secondary heat treatment. And carrying out induction heating by using an intermediate frequency heating furnace for one-time heat treatment, heating the continuous pipe body to 1000 ℃, and rapidly cooling the continuous pipe body by water after the heating is finished, so that the whole pipe wall is rapidly cooled to below the temperature of a phase transformation point, and the martensitic transformation is completed. After one heat treatment, the residual moisture in the water cooling process of the continuous pipe body is dried. And heating the pipe body to 650 ℃ by using an intermediate frequency induction heating furnace for heat preservation effective time, carrying out heat preservation heating when the temperature is reduced to 600 ℃, cooling to below 450 ℃ by air cooling, and finally cooling to room temperature by water.
The continuous pipe prepared by the method has the main properties: steel pipe specificationSteel with yield strength of 901MPa, tensile strength of 942MPa, elongation of 16.5%, hardness of 290HV and meeting API standard requirementsThe performance of the stage CT130 coiled tubing.
Example 2
The preparation of the low-carbon microalloy ultrahigh-strength continuous pipe in the embodiment 2 is carried out according to the following steps;
step 1, preparing a coiled plate
The raw materials of this example were proportioned according to the mass percentages of the chemical compositions in table 1, hot rolled coils were prepared by a controlled rolling and cooling technique, pickled, finished, inspected, and coiled into coils by a tension crimping machine for pipe making.
Step 2, plate bending longitudinal shearing and steel strip lengthening
Shearing the prepared coiled plate into a 159mm steel belt through a slitting machine set; in order to meet the length requirement of the continuous pipe, the ends of the front steel strip and the rear steel strip are processed into 45-degree bevel edges, I-shaped grooves are formed on the 45-degree bevel edges, butt welding is carried out on the front steel strip and the rear steel strip bevel edges by adopting an argon arc welding method, and after the welding line is cooled, the surface of the welding line is polished and cleaned. And then the welding seam is quickly heated to 960 ℃, is thermally rolled or hot forged, is naturally cooled to below 200 ℃, is quickly heated to 600 ℃ and is naturally cooled to room temperature.
Step 3, forming and welding
The side surface of the steel belt is planed into an I-shaped groove by adopting a side milling method, the width of the steel belt and the perpendicularity of the plate edges are accurately controlled, and the steel belt is molded by adopting an extrusion molding method; and (3) carrying out longitudinal welding on the formed steel strip by adopting a high-frequency induction welding technology, accurately controlling welding power and welding speed, wherein the welding power is 130kw, the welding speed is 21m/min, heating the welding seam to 900 when the welding seam is subjected to heat treatment, cooling to below 400 ℃ under the protection of nitrogen, carrying out water cooling, then sizing treatment, and ensuring that the welding seam has no defects of air holes and microcracks after welding. Finally, the pipe is welded into a straight-slit continuous pipe with the pipe diameter phi of 50.8mm and the wall thickness of 4.44 mm.
Step 4, off-line heat treatment
And carrying out induction heating by using an intermediate frequency heating furnace for one-time heat treatment, heating the continuous pipe body to 1050 ℃, and rapidly cooling the continuous pipe body by water after the heating is finished, so that the whole pipe wall is rapidly cooled to below the temperature of a phase transformation point, and the martensitic transformation is completed. And heating the pipe body to 700 ℃ by using an intermediate frequency induction heating furnace for heat preservation effective time, carrying out heat preservation heating when the temperature is reduced to 600 ℃, cooling to below 450 ℃ by air cooling, and finally cooling to room temperature by water.
The continuous pipe prepared by the method has the main properties: steel pipe specificationThe yield strength 841MPa, the tensile strength 874MPa, the elongation rate 18.9 percent and the hardness 272HV reach all properties of the steel grade CT120 continuous pipe required by the API standard.
Example 3
The preparation of the low-carbon microalloy ultrahigh-strength continuous pipe in the embodiment 3 is carried out according to the following steps;
step 1, preparing a coiled plate
The raw materials of this example were proportioned according to the mass percentages of the chemical compositions in table 1, hot rolled coils were prepared by a controlled rolling and cooling technique, pickled, finished, inspected, and coiled into coils by a tension crimping machine for pipe making.
Step 2, plate bending longitudinal shearing and steel strip lengthening
Shearing the prepared coiled plate into a 159mm steel belt through a slitting machine set; in order to meet the length requirement of a continuous pipe, the ends of the front steel strip and the rear steel strip are processed into 45-degree bevel edges, I-shaped grooves are formed on the 45-degree bevel edges, butt welding is carried out on the front steel strip bevel edges and the rear steel strip bevel edges by adopting a plasma arc welding method, then welding seams are quickly heated to 960 ℃, hot rolling or hot forging is carried out, natural cooling is carried out to below 200 ℃, then the temperature is quickly heated to 600 ℃, natural cooling is carried out to room temperature, and when the welding seams are cooled, the surfaces of the welding seams are polished and cleaned.
Step 3, forming and welding
The side surface of the steel belt is planed into an I-shaped groove by adopting a side milling method, the width of the steel belt and the perpendicularity of the plate edges are accurately controlled, and the steel belt is molded by adopting an extrusion molding method; and (3) carrying out longitudinal welding on the formed steel strip by adopting a high-frequency induction welding technology, accurately controlling welding power and welding speed, wherein the welding power is 130kw, the welding speed is 21m/min, heating the welding seam to 920 ℃ when the welding seam is subjected to heat treatment, cooling to below 400 ℃ under the protection of nitrogen, carrying out water cooling, then sizing treatment, and ensuring that the welding seam has no defects of air holes and microcracks after welding. Finally, the pipe is welded into a straight-slit continuous pipe with the pipe diameter phi of 50.8mm and the wall thickness of 4.44 mm.
Step 4, off-line heat treatment
And carrying out induction heating by using an intermediate frequency heating furnace for one-time heat treatment, heating the continuous pipe body to 1020 ℃, and rapidly cooling the continuous pipe body by water after the heating is finished, so that the whole pipe wall is rapidly cooled to below the temperature of a phase transformation point, and the martensitic transformation is completed. And heating the pipe body to 660 ℃ by using an intermediate frequency induction heating furnace for heat preservation effective time, carrying out heat preservation heating when the temperature is reduced to 600 ℃, cooling to below 450 ℃ by air cooling, and finally cooling to room temperature by water.
The continuous pipe prepared by the method has the main properties: steel pipe specificationThe yield strength is 1034MPa, the tensile strength is 1068MPa, the elongation is 18.7%, the hardness is 282HV, and the properties of the steel grade CT120 continuous pipe meet the requirements of API standards.
Example 4
The preparation of the low-carbon microalloy ultrahigh-strength continuous pipe in the embodiment 4 is carried out according to the following steps;
step 1, preparing a coiled plate
The raw materials of this example were proportioned according to the mass percentages of the chemical compositions in table 1, hot rolled coils were prepared by a controlled rolling and cooling technique, pickled, finished, inspected, and coiled into coils by a tension crimping machine for pipe making.
Step 2, plate bending longitudinal shearing and steel strip lengthening
Shearing the prepared coiled plate into a 159mm steel belt through a slitting machine set; in order to meet the length requirement of a continuous pipe, the ends of the front steel strip and the rear steel strip are processed into 45-degree bevel edges, I-shaped grooves are formed on the 45-degree bevel edges, butt welding is carried out on the front steel strip and the rear steel strip bevel edges by adopting a plasma arc welding method, and after the welding line is cooled, the surface of the welding line is polished and cleaned. And then the welding seam is quickly heated to 960 ℃, is thermally rolled or hot forged, is naturally cooled to below 200 ℃, is quickly heated to 600 ℃ and is naturally cooled to room temperature.
Step 3, forming and welding
The side surface of the steel belt is planed into an I-shaped groove by adopting a side milling method, the width of the steel belt and the perpendicularity of the plate edges are accurately controlled, and the steel belt is molded by adopting an extrusion molding method; and (3) carrying out longitudinal welding on the formed steel strip by adopting a high-frequency induction welding technology, accurately controlling welding power and welding speed, wherein the welding power is 130kw, the welding speed is 21m/min, heating the welding seam to 960 ℃ when carrying out heat treatment on the welding seam, cooling to below 400 ℃ under the protection of nitrogen, carrying out water cooling, then carrying out sizing treatment, and ensuring that the welding seam has no defects of air holes and microcracks after welding. Finally, the pipe is welded into a straight-slit continuous pipe with the pipe diameter phi of 50.8mm and the wall thickness of 4.44 mm.
Step 4, off-line heat treatment
And carrying out induction heating by using an intermediate frequency heating furnace for one-time heat treatment, heating the continuous pipe body to 1040 ℃, and rapidly cooling the continuous pipe body by water after the heating is finished, so that the whole pipe wall is rapidly cooled to below the temperature of a phase transformation point, and the martensitic transformation is completed. And heating the pipe body to 680 ℃ by using an intermediate frequency induction heating furnace for heat preservation effective time, carrying out heat preservation heating when the temperature is reduced to 600 ℃, cooling to below 450 ℃ by air cooling, and finally cooling to room temperature by water.
The continuous pipe prepared by the method has the main properties: steel pipe specificationThe yield strength is 758MPa, the tensile strength is 793MPa, the elongation is 17.9%, the hardness is 284HV, and the performances of the steel grade CT120 continuous pipe meet the requirements of API standards.
The four embodiments of the invention prepare the low-carbon micro-alloy ultrahigh-strength continuous pipe, the yield strength is 758-1034MPa, the tensile strength is 793-1068MPa, and the outer diameter range isThe wall thickness is 2.77-5.2mm, and the length is 500-10000m. Meets the requirements of API standardThe ultra-high strength continuous pipe has the advantages that all performances of the ultra-high strength continuous pipe are achieved, the weld joint structure of the pipe body and the base metal structure tend to be consistent, the bending fatigue life of the continuous pipe is prolonged, and the operation safety of the continuous pipe is improved.
Claims (10)
1. The preparation method of the low-carbon microalloy ultrahigh-strength continuous pipe is characterized by comprising the following steps of:
step 1, preparing a coiled plate;
step 2, longitudinal shearing of the coiled plate and lengthening of the steel belt;
step 3, molding and welding;
and 4, offline heat treatment.
2. The method for preparing the low-carbon microalloy ultrahigh-strength continuous pipe according to claim 1, wherein the coiled plate prepared in the step 1 is sheared into steel strips with corresponding widths through a slitting machine set according to the specification requirement of the continuous pipe, the end parts of the front steel strip and the rear steel strip are obliquely cut into 45 degrees and are processed into I-shaped grooves, and the I-shaped grooves are assembled and welded by adopting an argon arc welding or plasma arc welding method; and (5) polishing after welding to remove the surplus height of the weld seam, and performing post-welding rolling deformation heat treatment on the oblique weld seam.
3. The method for preparing the low-carbon micro-alloy ultrahigh-strength continuous pipe according to claim 1, wherein in the step 2, the welding line is rapidly heated to 960 ℃, is thermally rolled or forged, is naturally cooled to below 200 ℃, is rapidly heated to 600 ℃, is naturally cooled to room temperature, and is polished and cleaned after the welding line is cooled.
4. The method for preparing the low-carbon microalloy ultrahigh-strength continuous pipe according to claim 1, wherein in the step 2, the steel strip is curled and formed by a forming unit, a welding squeeze roller is adjusted to ensure that the edges of the curled steel strip are tightly attached and have no offset phenomenon, a high-frequency induction welding method is adopted to carry out straight seam welding, a medium-frequency induction heating mode is adopted to carry out welding seam heat treatment on a welding seam after the welding is completed, sizing treatment is carried out, the required outside diameter size of the continuous pipe is obtained, and the continuous pipe is wound on a winding drum with corresponding specification.
5. The method for preparing a low-carbon micro-alloy ultrahigh-strength continuous pipe according to claim 4, wherein the welding seam is heated to 900-960 ℃ during the welding seam heat treatment in the step 3, and is cooled to below 400 ℃ under the protection of nitrogen gas for water cooling.
6. The method for preparing the low-carbon microalloy ultrahigh-strength continuous pipe according to claim 4, wherein the continuous pipe wound in the step 3 is re-opened through a heat treatment unit to perform full-pipe heat treatment, and the full-pipe heat treatment process comprises three links, namely primary heat treatment, blow-drying and secondary heat treatment.
7. The method for preparing the low-carbon micro-alloy ultrahigh-strength continuous pipe according to claim 6, wherein the specific process of the step 4 is as follows:
when in primary heat treatment, a plurality of groups of medium-frequency heating furnaces are adopted to perform full-tube induction heating, the continuous tube body is heated to 1000-1050 ℃, after the heating is completed, the continuous tube body rapidly enters a cooling water system to be cooled, the flow and the pressure of the water are determined by the wall thickness of the continuous tube and the tube making speed, the tube wall is ensured to be rapidly cooled to be below the phase transition point temperature, and the tissue transformation is completed;
and (3) rapidly removing residual moisture in the surface water cooling process of the continuous tube by using compressed air, performing secondary heat treatment, combining and using a plurality of groups of medium-frequency induction heating furnaces, heating to 650-700 ℃, ensuring sufficient heating and heat preservation effective length, manufacturing a movable track by using the last group of medium-frequency induction heating furnaces, moving back and forth according to different temperatures in winter and summer, ensuring that the temperature before entering the heating furnaces is not lower than 600 ℃, finishing tempering structure transformation, cooling to below 450 ℃ by air cooling, cooling to room temperature by using a spray water tank, finishing the whole tube heat treatment process, and finally coiling the whole tube heat treated continuous tube by using a crimping machine to obtain the ultrahigh-strength continuous tube with the required length.
8. The method for preparing the low-carbon micro-alloy ultrahigh-strength continuous pipe according to claim 7, wherein in the step 1, raw materials of plates are selected according to a proportion, molten iron is used as a main raw material, alloy elements are added into the raw materials, a steel coil is subjected to hot rolling to obtain a ferrite and pearlite blending balance structure, and after pickling, finishing and detection, the steel coil is curled into a coiled plate by a tension curler for pipe production.
9. The method for preparing the low-carbon micro-alloy ultrahigh-strength continuous pipe according to claim 1, wherein the chemical components in the raw materials of the plates of the continuous pipe in the step 1 are as follows by mass percent: 0.17-0.30% of C, 0.12-0.50% of Si, 0.60-1.8% of Mn, less than or equal to 0.02% of P, less than or equal to 0.003% of S, and the balance of Fe and unavoidable impurities.
10. The method for preparing a low-carbon micro-alloy ultrahigh-strength continuous pipe according to claim 9, wherein the raw materials in the step 1 further comprise any one or more alloy elements in Cr, ni, cu, ti, nb, mo, and the total amount of the alloy elements is not more than 5.0%.
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