NL2032614B1 - Process for manufacturing low-temperature die-pressing tee joint by x80 steel plate - Google Patents
Process for manufacturing low-temperature die-pressing tee joint by x80 steel plate Download PDFInfo
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- NL2032614B1 NL2032614B1 NL2032614A NL2032614A NL2032614B1 NL 2032614 B1 NL2032614 B1 NL 2032614B1 NL 2032614 A NL2032614 A NL 2032614A NL 2032614 A NL2032614 A NL 2032614A NL 2032614 B1 NL2032614 B1 NL 2032614B1
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- temperature
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- tee joint
- welding
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- 238000000034 method Methods 0.000 title claims abstract description 35
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 23
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 19
- 239000010959 steel Substances 0.000 title claims abstract description 19
- 238000007723 die pressing method Methods 0.000 title abstract description 7
- 238000010438 heat treatment Methods 0.000 claims abstract description 29
- 238000005496 tempering Methods 0.000 claims abstract description 28
- 238000007731 hot pressing Methods 0.000 claims abstract description 10
- 238000000465 moulding Methods 0.000 claims abstract description 10
- 238000001816 cooling Methods 0.000 claims abstract description 8
- 238000007599 discharging Methods 0.000 claims abstract description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000005096 rolling process Methods 0.000 claims abstract description 5
- 238000005520 cutting process Methods 0.000 claims abstract description 3
- 238000007493 shaping process Methods 0.000 claims abstract description 3
- 238000003466 welding Methods 0.000 claims description 66
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 18
- 238000003825 pressing Methods 0.000 claims description 15
- 238000005498 polishing Methods 0.000 claims description 12
- 229910052786 argon Inorganic materials 0.000 claims description 9
- 238000001514 detection method Methods 0.000 claims description 9
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 8
- 238000010079 rubber tapping Methods 0.000 claims description 6
- 238000005507 spraying Methods 0.000 claims description 6
- 239000003822 epoxy resin Substances 0.000 claims description 5
- 229920000647 polyepoxide Polymers 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 4
- 239000003345 natural gas Substances 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 3
- 238000007689 inspection Methods 0.000 claims description 3
- 239000006247 magnetic powder Substances 0.000 claims description 3
- 238000009659 non-destructive testing Methods 0.000 claims description 3
- 238000013021 overheating Methods 0.000 claims description 3
- 238000004513 sizing Methods 0.000 claims description 3
- 238000012360 testing method Methods 0.000 claims description 3
- 230000037303 wrinkles Effects 0.000 claims description 3
- 239000007858 starting material Substances 0.000 claims 2
- 238000013016 damping Methods 0.000 claims 1
- 238000010891 electric arc Methods 0.000 claims 1
- 230000001105 regulatory effect Effects 0.000 claims 1
- 238000002604 ultrasonography Methods 0.000 claims 1
- 238000010791 quenching Methods 0.000 abstract description 10
- 230000000171 quenching effect Effects 0.000 abstract description 10
- 239000002994 raw material Substances 0.000 abstract description 6
- 239000010410 layer Substances 0.000 description 8
- 239000000463 material Substances 0.000 description 6
- 239000004429 Calibre Substances 0.000 description 4
- 230000001629 suppression Effects 0.000 description 3
- 238000011161 development Methods 0.000 description 2
- 238000007590 electrostatic spraying Methods 0.000 description 2
- 239000011229 interlayer Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000007517 polishing process Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000009747 press moulding Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 235000013619 trace mineral Nutrition 0.000 description 1
- 239000011573 trace mineral Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
-
- 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
- B21C37/15—Making tubes of special shape; Making tube fittings
- B21C37/28—Making tube fittings for connecting pipes, e.g. U-pieces
- B21C37/29—Making branched pieces, e.g. T-pieces
-
- 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
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
-
- 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
- C21D9/085—Cooling or quenching
-
- 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
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L41/00—Branching pipes; Joining pipes to walls
- F16L41/02—Branch units, e.g. made in one piece, welded, riveted
- F16L41/021—T- or cross-pieces
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L9/00—Rigid pipes
- F16L9/02—Rigid pipes of metal
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
Disclosed is a process for manufacturing a low-temperature die-pressing tee joint by an X80 steel plate. The process comprises: selecting the X80 steel plate as a raw material; cutting the raw material into a rectangular blank; rolling the rectangular blank into a cylindrical blank; pre- treating the surface of the welded cylindrical blank, and performing primary tempering treatment on the pre-treated cylindrical blank; performing hot-pressing moulding treatment on the blank subjected to the primary tempering treatment; immersing the whole teejoint pipe blank subjected to the hot-pressing moulding treatment into a water tank for cooling to room temperature; and shaping and flattening the cooled tee joint pipe blank, putting the tee joint pipe blank into a heat treatment furnace for quenching and secondary tempering treatment, then quickly cooling to room temperature, performing secondary tempering treatment, maintaining the temperature, and then discharging and naturally cooling in air after temperature maintaining.
Description
PROCESS FOR MANUFACTURING LOW-TEMPERATURE DIE-PRESSING TEE JOINT BY
X80 STEEL PLATE
The present invention belongs to the technical field of processing of tee joint pipe fittings, and particularly relates to a process for manufacturing a low-temperature die-pressing tee joint by an X80 steel plate.
In recent years, along with the large-scale demands and strategic development and storage of clean energy such as natural gas at home and abroad, long-distance pipeline engineering is designed and constructed with large transportation volume and low energy consumption. The adoption of high-steel-grade, large-calibre and high-pressure pipelines for transportation has become the development trend of long-distance pipeline engineering. Meanwhile, the low- temperature resistance of a pipeline material is improved, and heat preservation and heat tracing facilities of pipelines in alpine regions are removed.
A high-steel-grade material is easily subjected to low-temperature brittle failure when a bare pipe manufactured through the high-steel-grade-material runs for a long time in an extreme low- temperature environment (-45°C), and due to the limitation of an alloy system of a high-steel- grade pipeline steel material and a controlled rolling process, it is difficult to achieve high toughness of the high-steel-grade pipeline steel material in a low-temperature environment. A large-calibre seamed tee joint has a plurality of quality risk points (due to the technical bottlenecks that the all parts of the whole large-calibre tee joint have different thickness, weld metal of a high-steel-grade product is sensitive to a hot processing temperature, the strength and the toughness are in an inverse proportion trend along with the temperature change, etc.), and moreover, the stress of the tee joint is relatively complex due to the influence of factors such as installation stress, running stress and geological change caused by the use characteristics of the tee joint, so the final overall quality state of the tee joint must to accurately meet the requirements of engineering standards, and the researched and developed process and key nodes must ensure the quality stability after batch production so to ensure the safe operation of application engineering.
A patient CN108239720A discloses a method for pressing a tee joint pipe fitting by an X80 steel plate. According to the method, the temperature of pressing and moulding is 900-1,000°C, quenching is carried out at the temperature of 930-1,000°C, and then tempering is carried out at the temperature of 580-650°C. According to the present invention, the tee joint pipe fitting is moulded by pressing, which causes the problems of large stress in the pipe fitting, non-uniform structure of the pipe fitting and the like, consequently, the service life of the tee joint pipe fitting is shortened, and the product stability is low.
How to improve the uniformity, strength, toughness, and low-temperature resistance of the die-pressed tee joint is the problem urgently to be solved currently.
An objective of the present invention is to provide a process for manufacturing a low- temperature die-pressing tee joint by an X80 steel plate. The process is used for manufacturing a homogeneous, high-strength and high-toughness tee joint pipe fitting by a technical means of combining welding and pressing.
In order to achieve the above objective, the present invention discloses the process for manufacturing the low-temperature die-pressing tee joint by the X80 steel plate. The process comprises the following steps: selecting the X80 steel plate as a raw material; cutting the raw material into a rectangular blank; rolling the rectangular blank into a cylindrical blank, and welding longitudinal welding seams of the cylindrical blank, wherein in the welding process, when argon arc welding is carried out for bottoming, the attenuation time of electric arcs is set to be 6 s or above, a first layer of welding seams are filled by argon arc welding, a second layer of welding seams and a third layer of welding seams are sequentially filled with ¢ 2.4 welding rods and ¢ 3.2 welding rods, and the rest welding seams are filled with ¢ 37 welding rods; pre-treating the surface of the welded cylindrical blank: polishing the welding seams, including polishing the surplus height of the welding seams, removing surface scratch areas and removing welding spatter, polishing welding seam joints and grinding the welding seams; performing primary tempering treatment on the pre-treated cylindrical blank; performing hot- pressing moulding treatment on the blank subjected to the primary tempering treatment; immersing the whole tee joint pipe blank subjected to the hot-pressing moulding into a water tank for cooling to room temperature; and shaping and flattening the cooled tee joint pipe blank, putting the tee joint pipe blank into a heat treatment furnace for quenching and secondary tempering process treatment, then quickly cooling to room temperature, performing secondary tempering treatment, maintaining the temperature, and then discharging and naturally cooling in air after temperature maintaining.
Preferably, after the welding seams are polished, epoxy resin powder is sprayed on the outer surface of the pre-treated cylindrical blank through a high-pressure electrostatic spraying tool, the spraying distance is 10-20 cm, and the spraying criterion is that epoxy resin is visually and uniformly distributed, and the original metal colour is not exposed.
Preferably, the heating temperature in hot pressing on the blank subjected to primary tempering treatment is 920°C, the blank is slowly cooled to 100-120°C, and the constant temperature is kept for 1 h.
Preferably, the step of performing primary tempering treatment on the pre-treated cylindrical blank, and performing hot-pressing moulding treatment on the blank subjected to the primary tempering treatment comprises the following steps: 1) charging and heating: charging the blank into a natural gas heat treatment furnace, wherein the blank is isolated from a furnace car by a sizing block at the bottom, the distance between the tee joints is larger than or equal to 200 mm, and the temperature of 400°C or above is increased at a speed of < 200°C/h; 2) heating the tee joint blank to 880 + 10°C, performing temperature maintaining at 1.5 min/mm, discharging and flattening, wherein the length of a short shaft after pressing is not greater than the inner diameter of a die; 3) continuously charging and heating to 880 + 10°C, maintaining the temperature at 1.5 min/mm, then discharging, quenching 2/3 part of the tee joint blank, and quickly putting the blank into the die for bulging, wherein the uncooled part flows along an inner cavity of the die under the pressure to form a branch pipe; 4) repeating the process 3) until the branch pipe meets the manufacturing requirements; 5) tapping: measuring a certain distance from the bottom of the tee joint serving as a reference to the branch pipe, measuring a certain distance from the shoulder of a main pipe serving as a reference to the branch pipe, drawing points and connecting lines, and tapping by a burning torch; and 6) continuously heating the tee joint blank to 880 + 10°C, maintaining the temperature at 1.5 min/mm, then quickly putting the tee joint into the die after the main pipe is partially quenched, putting a drawing die into the branch pipe, and pressing the drawing die by a press machine, wherein the drawing die in vertically pressed to ensure that the branch pipe cannot be pressed to be straight during pressing and the branch pipe meets the manufacturing requirement.
Preferably, the X80 steel comprises the following elements in percentage by weight: 0.06% of C, 1.5% of Mn, 0.23% of Si, 0.15% of Cr, 0.39% of Mo, 0.037% of V, 0.77% of Ni, 0.045% of
Nb, 0.14% of Cu and the balance Fe and inevitable impurities, wherein the non-metallic inclusions are < 1.5 grade, the grain size is 2 10 grade, and the CEpem is 0.2%.
Preferably, during welding, the preheating temperature is 190-210°C, the interlayer temperature is 150-200°C, the welding current is controlled to be < 180 A, the welding speed is = 20 cm/min, and the heat input is < 20 KJ/cm.
Preferably, when the blank subjected to primary tempering treatment is subjected to hot pressing, the heating temperature is 920°C, the blank is slowly cooled to 100-120°C, and the constant temperature is kept for 1 h.
Preferably, the process further comprises the step of performing 100% radiographic inspection on the welding seams of the processed tee joint pipe fitting, wherein the welding seams reaching the second grade are qualified,
performing a mechanical property test on the tee joint, and ensuring that the mechanical property of the tee joint reaches the standard; performing appearance detection, wherein the tee joint is free from cracks, over-burning and over-heating, the surface is free from hard spots, and the root of the branch pipe of the tee joint is free from wrinkles; and performing non-destructive testing, performing magnetic powder and ultrasonic detection on the tee joint according to standard requirements, wherein the tee joint reaching | grade in detecting is qualified, and the finished product of the pressure pipe tee joint is prepared after the detection result shows the tee joint is qualified.
Compared with the prior art, the present invention has the advantages that: the tee joint pipe fitting is manufactured by combining a welding process and a pressing forming process by the X80 steel plate, the loss allowance of grain size and strength caused by repeated heating and long heating time in the machining process is improved, and the tee joint pipe fitting can be normally used for a long time in extremely cold weather at the temperature of -45°C; and the tee joint pipe fitting manufactured by the process has fine grain size, high strength and low welding crack sensitivity coefficient, and the homogeneous degree of each part of the product is greatly improved, so the tee joint pipe fitting can be applied to an operating environment at the temperature of -45°C.
It should be noted that the embodiments in the present invention and the features of the embodiments may be combined with each other in the case of no conflict. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.
The embodiment provides a process for manufacturing a low-temperature die-pressing tee joint by an X80 steel plate, and the process comprises the following steps:
The X80 steel plate with the thickness of 58 mm is selected as a raw material, wherein the
X80 steel plate comprises the following elements in percentage by weight: 0.06% of C, 1.5% of
Mn, 0.23% of Si, 0.15% of Cr, 0.39% of Mo, 0.037% of V, 0.77% of Ni, 0.045% of Nb, 0.14% of
Cu and the balance Fe and inevitable impurities at 1.5 grade, the grain size is 10 grade, and
CEpem is 0.2%.
The raw material is cut into a rectangular blank.
The rectangular blank is rolled into a cylindrical blank, and longitudinal welding seams of the cylindrical blank are welded; and during the welding treatment, parameters are set as follows: the preheating temperature is 200°C, the interlayer temperature is 180°C, the welding current is controlled to be 150 A, the welding speed is 20 cm/min, and the heat input is 18
KJ/em.
During carrying out argon arc welding for bottoming, the attenuation time of electric arcs is set to be 6 s or above to prevent arc suppression cracks; the internal argon filling flow is 10-20 5 L/min, and the argon filling flow is 8-10 L/min in the welding process to prevent oxidation of the inner wall; a first layer of weld seams are filled by argon arc welding, a second layer of weld seams and a third layer of weld seams are sequentially filled with ¢ 2.5 and ¢ 3.2 welding rods, and the rest weld seams are filled with ¢ 40 welding rods. The internal argon filling is stopped after the first layer of weld seams are filled. An overlapping method is adopted during arc suppression in welding rod arc welding, namely arc quenching is performed at intervals of 2-4 times, the time for replacing the welding rods is shortened as much as possible, and a hot joint is connected to prevent the arc suppression cracks. Multi-layer and multi-pass welding is adopted, the width of a weld bead does not exceed 3 times of the diameter of the welding rods, and the thickness does not exceed the diameter of the welding rods.
The surface of the welded cylindrical blank is preheated, including welding seam polishing.
The welding seam polishing process comprises the following steps: polishing the surplus height of the welding seams, removing a surface scratch area, removing welding spatter, polishing welding seam joints and grinding the welding seams. The polishing quality can be set according to actual requirements, for example, the whole welding seam joints are free from burrs, pits and poor welding parts, and the surface has no obvious non-uniform polishing phenomenon after polishing.
Epoxy resin powder is sprayed on the inner surface and the outer surface of the pre-treated blank by a high-voltage electrostatic spraying tool, wherein the spraying distance is 10-20 cm, and the spraying criterion is that epoxy resin is visually and uniformly distributed, and the original metal colour is not exposed. Primary tempering treatment is performed on the pre- treated cylindrical blank, fixed spot welding is performed on the longitudinal welding seams of the cylindrical blank, then the cylindrical blank is put into a heat treatment furnace for tempering treatment to eliminate the rolling stress of high-strength steel; and the tempering treatment temperature is 750°C, and the temperature is maintained for 145 min.
Hot-press moulding treatment is performed on the blank subjected to the primary tempering treatment, namely performing the tee joint moulding process in a heating state according to the sequence of flattening-rounding-bulging-tapping- drawing and roundness correcting, so as to obtain a large-calibre tee joint pipe blank with the diameter of 1, 422-1, 422 mm, wherein the heating temperature is 810-930°C, preferably 920°C; and the blank is slowly cooled to the temperature of 100-120°C, and constant temperature is kept for 1 h.
The step for performing hot-pressing moulding treatment on the blank subjected to primary tempering treatment specifically comprises the following steps:
1) charging and heating: charging the blank into a natural gas heat treatment furnace, wherein the blank is isolated from a furnace car by a sizing block at the bottom, the distance between the tee joints is = 200 mm, and the temperature of 400°C or above is increased at a speed of < 200°C/h; 2) heating the tee joint blank to 880 + 10°C, performing temperature maintaining (ensuring that the tee joint is burnt through) at 1.5 min/mm, discharging and flattening (ensuring that the welding seams is in the centre of the tee joint), wherein the length of a short shaft after pressing is not greater than the outer diameter of the tee joint (the inner diameter of a die); 3) continuously charging and heating to 880 + 10 °C, maintaining temperature at 1.5 min/mm, then discharging, and quenching 2/3 part of the tee joint pipe blank {the welding seams are at the bottom), and quickly putting the blank into the die for bulging, wherein the uncooled part flows along an inner cavity of the die under the pressure to form a branch pipe; 4) repeating the process 3) until the branch pipe meets the manufacturing requirement; 5) tapping: measuring a certain distance from the bottom of the tee joint serving as a reference to the branch pipe, measuring a certain distance from the shoulder of a main pipe serving as a reference to the branch pipe, drawing points and connecting lines, and tapping by a burning torch, wherein the distance is set according to the manufacturing standard of the tee joint pipe; 6) continuously heating the tee joint blank to 880 + 10°C, maintaining the temperature for 1.5 min/mm, quickly putting the tee joint into the die after the main pipe is partially quenched, putting a drawing die into the branch pipe, pressing the drawing die by a press machine, wherein the drawing die in vertically pressed to ensure that the branch pipe cannot be pressed to be straight during pressing and the branch pipe meets the manufacturing requirement; and 7) removing the end: measuring a certain distance from the centre of the branch pipe serving as a reference to the end of the main pipe, measuring a certain distance from the bottom of the tee joint serving as a reference to the branch pipe, and removing the redundant part by the burning torch.
The whole tee joint pipe blank subjected to hot-pressing moulding is immersed into the water tank for cooling to room temperature.
The cooled tee joint pipe blank is shaped and flattened.
Then the tee joint pipe fitting is put into the heat treatment furnace for quenching and secondary tempering process treatment, and after the tee joint pipe fitting is subjected to final quenching and secondary tempering heat treatment, all trace elements are completely dissolved in crystals to form an extremely fine bainite structure so that the surfaces and core performances of a finished product base material and the welding seams are uniform and consistent. Therefore, a high-quality tee joint finished product which meets the standard and is suitable for being butted with a main pipeline is obtained. When putting tee joint pipe fitting into the heat treatment furnace for quenching and secondary tempering process treatment, the tee joint pipe fitting is stacked in the heat treatment furnace in a single layer, the welding seams are positioned at a horizontal position, the interval between the tee joints and the interval between tee joints and the furnace wall and the furnace bottom are = 300 mm, preferably 350 mm; the guenching temperature is 865-885°C, preferably 875°C; and the temperature is maintained for 50 min; after quenching and temperature maintaining are finished, the tee joint pipe fitting is quickly put into water within 1 min and is continuously moved in the water tank at a constant speed until the whole pipe fitting is cooled to room temperature within 5 min so as to achieve high hardenability; then secondary tempering is carried out, wherein the secondary tempering temperature is 640-660°C, preferably 650°C, and the temperature is maintained for 150 min; and after temperature maintaining is finished, the tee joint pipe fitting is discharged out of the furnace and naturally cooled in the air. 100% radiographic inspection is performed on the welding seams of the tee joint pipe fitting processed by the above method, wherein the welding seams reaching the second grade are qualified.
A mechanical property test is performed on the tee joint to ensure that the mechanical property of the tee joint reaches the standard.
Appearance detection is performed, wherein the tee joint is free from cracks, over-burning, over-heating and the like, and the surface is free from hard spots; the root of the branch pipe of the tee joint is free from wrinkles; and any defects on the tee joint pipe body cannot be treated with welding repair.
Non-destructive testing is performed, magnetic powder and ultrasonic detection are carried out on the tee joint according to standard requirements, wherein the tee joint reaching | grade in detecting is qualified, and the finished product of the pressure pipe tee joint is prepared after the detection result shows the tee joint is qualified.
The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited to this. Any changes or substitutions that can be easily conceived by any person skilled in the art within the technical scope disclosed in the present invention should be covered by the protection scope of the present application.
Therefore, the protection scope of the present invention should be subject to the protection scope ofthe claims.
Claims (8)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL2032614A NL2032614B1 (en) | 2022-07-27 | 2022-07-27 | Process for manufacturing low-temperature die-pressing tee joint by x80 steel plate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL2032614A NL2032614B1 (en) | 2022-07-27 | 2022-07-27 | Process for manufacturing low-temperature die-pressing tee joint by x80 steel plate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| NL2032614B1 true NL2032614B1 (en) | 2024-02-05 |
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| NL2032614A NL2032614B1 (en) | 2022-07-27 | 2022-07-27 | Process for manufacturing low-temperature die-pressing tee joint by x80 steel plate |
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