Titanium alloy continuous welding pipe and preparation method thereof

Abstract

The invention provides a titanium alloy continuous welded pipe and a preparation method thereof. The preparation method comprises the following steps: uncoiling a plurality of titanium alloy welded pipe strips to obtain a plurality of titanium alloy strips; the multiple titanium alloy strips are spliced end to end, and first welding is conducted on the splicing positions to form welding seams; a cover face is formed on the front face of the weld joint through swing welding, first induction heating and rolling treatment are sequentially conducted on a welding heat affected zone, and a continuous strip is obtained; the cover surface covers the welding heat affected zone, and the temperature of the first induction heating is 935-950 DEG C; the continuous strip is sequentially subjected to forming treatment, second welding, pre-sizing treatment, second induction heating and fine sizing treatment, and the titanium alloy continuous welded pipe is obtained; the second welding mode is laser welding, and the temperature of the second induction heating is 600-800 DEG C. The titanium alloy continuous welded pipe manufactured through the method is good in welding quality and suitable for manufacturing long pipes.

Description

Technical Field

[0001] The present application relates to the technical field of titanium alloy materials, and in particular to a titanium alloy continuous welded pipe and a preparation method thereof. Background Art

[0002] Titanium alloy continuous welded pipes have the advantages of small size, multiple recycling and low cost, and have been widely used in oil and gas field operations.

[0003] At present, the continuous pipes used in oil production are mainly high-strength low-alloy steel; however, as the depth of mining increases, the weight of high-strength low-alloy steel pipes also increases, resulting in limited downhole depth; and as the environmental conditions of oil and gas mining become increasingly harsh, especially in oil and gas fields containing sulfur components such as high hydrogen sulfide, the corrosion problem of conventional low-alloy steel continuous pipes has gradually become prominent, restricting the progress of oil production. Titanium alloy continuous welded pipes with excellent corrosion resistance and high toughness are increasingly widely used in the oil production industry.

[0004] At present, the length of common titanium alloy coils is about 1000m, and how to prepare titanium alloy continuous tubes with good performance and a length greater than 10000m is an urgent problem to be solved. Summary of the invention

[0005] Based on this, one or more embodiments of the present application provide a method for preparing a titanium alloy continuous welded tube with good tube welding quality and suitable for preparing long tubes, and a corresponding titanium alloy continuous welded tube.

[0006] According to a first aspect of an embodiment of the present application, a method for preparing a titanium alloy continuous welded tube is provided, comprising the following steps:

[0007] Uncoiling a plurality of titanium alloy welded pipe strips to obtain a plurality of titanium alloy strips;

[0008] Splicing the plurality of titanium alloy strips end to end, and performing a first welding process at the splicing position to form a weld;

[0009] A cap is formed on the front of the weld by swing welding, and the welding heat affected zone is subjected to first induction heating and rolling treatment in sequence to obtain a continuous strip; the cap covers the welding heat affected zone, and the temperature of the first induction heating is 935°C to 950°C;

[0010] The continuous strip is subjected to forming treatment, second welding, pre-sizing treatment, second induction heating and precision sizing treatment in sequence to obtain a titanium alloy continuous welded tube;

[0011] Among them, the second welding method is laser welding, and the second induction heating temperature is 600°C~800°C.

[0012] In one embodiment, the step of splicing a plurality of the titanium alloy strips comprises:

[0013] The strip heads and strip tails of the plurality of titanium alloy strips are cut and polished, and the strip head of one titanium alloy strip is spliced ​​with the strip tail of another titanium alloy strip.

[0014] In one embodiment, before the splicing step, the following steps are also included:

[0015] A partial position of one of the titanium alloy strips is subjected to forming treatment, second welding, pre-sizing treatment, second induction heating and precision sizing treatment in sequence to obtain a titanium alloy material, wherein the titanium alloy material comprises a pipe and a titanium alloy strip connected in sequence.

[0016] In one embodiment, after the splicing step and before the first welding step, the following steps are further included:

[0017] Arc-starting plates and arc-extinguishing plates are welded on both sides of the splicing position, and a U-shaped support is installed on the back of the splicing position.

[0018] In one embodiment, the welding speed of the swing welding is 0.3m / min~0.5m / min, the welding current is 180A~280A, the flow rate of the shielding gas is 10L / min~18L / min, the swing width is 1.5mm~2.5mm, and the swing frequency is 2Hz~4Hz.

[0019] In one embodiment, the first welding method includes one or more of metal inert gas shielded welding and argon arc welding with filler wire;

[0020] Optionally, the welding speed of the metal inert gas shielded welding is 0.4m / min~0.7m / min, the welding current is 200A~320A, the flow rate of the front shielding gas is 10L / min~18L / min, and the flow rate of the back shielding gas is 5L / min~12L / min.

[0021] In one embodiment, the laser welding includes one or more of circular scanning galvanometer laser welding and dual-beam laser welding;

[0022] Optionally, the welding speed of the circular scanning galvanometer laser welding is 0.8m / min~1.2m / min, the laser power is 3000W~4500W, the laser tilt angle is 5°~8°, the scanning width of the scanning galvanometer is 0.2mm~2.5mm, and the frequency of the scanning galvanometer is 150Hz~220Hz;

[0023] Optionally, the welding speed of the dual-beam laser welding is 0.6m / min~1.2m / min, the laser power is 2000W~4500W, the laser tilt angle is 5°~8°, and the light spacing of the dual beams is 1mm~3mm.

[0024] In one embodiment, the preparation method satisfies at least one of the following characteristics:

[0025] (1) The deformation of rolling treatment is 50%~80%;

[0026] (2) The forming process is multi-pass roller forming, and the deformation of each pass of roller forming is 10%~15%.

[0027] A titanium alloy continuous welded pipe is prepared by adopting the above preparation method.

[0028] In one embodiment, the length of the titanium alloy continuous welded pipe is greater than 10,000 m.

[0029] Compared with the traditional technology, this application has the following beneficial effects:

[0030] The present application adds a cover to the front of the splicing position, and through induction heating and rolling treatment, the structural properties of the weld position are consistent with the parent material properties, thereby improving the comprehensive performance of the titanium alloy continuous welded pipe; and combined with the laser welding method, the precision of the weld is improved, welding defects are reduced, and it also has the advantage of long-term continuous welding. In this way, the titanium alloy continuous welded pipe prepared by the method of the present application has excellent comprehensive performance and can be longer than 10,000 meters. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 This is a schematic diagram of the installation positions of the arc striking plate and the arc extinguishing plate in one embodiment of the present application;

[0033] Figure 2 This is a schematic diagram of the weld structure before and after rolling treatment in one embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present application. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the present application, etc. can be purchased from the market or can be prepared by existing methods.

[0036] Traditional technology proposes to use laser welding and TIG arc hybrid welding to weld the Ru-doped high-strength and high-plasticity titanium alloy continuous tube. However, the introduction of arc welding weakens the technical advantage of laser welding for long-term continuous welding. Long-term TIG arc welding will have unavoidable problems such as tungsten needle burning and tungsten doping in the weld, which has a negative impact and is not conducive to long-term continuous welding.

[0037] Some embodiments of the present application provide a method for preparing a titanium alloy continuous welded tube, including S10 to S40.

[0038] S10: uncoiling the plurality of titanium alloy welded pipe strips to obtain a plurality of titanium alloy strips;

[0039] S20: splicing the plurality of titanium alloy strips end to end, and performing a first welding at the splicing position to form a weld;

[0040] S30: forming a capping surface on the front side of the weld by swing welding, and sequentially performing first induction heating and rolling treatment on the welding heat affected zone to obtain a continuous strip; the capping surface covers the welding heat affected zone, and the temperature of the first induction heating is 935°C to 950°C;

[0041] S40: performing forming treatment, second welding, pre-sizing treatment, second induction heating and fine sizing treatment on the continuous strip in sequence to obtain a titanium alloy continuous welded tube;

[0042] The second welding method in S40 is laser welding, and the temperature of the second induction heating is 600° C. to 800° C.

[0043] It can be understood that the titanium alloy welded pipe strip can be any welded pipe strip commonly used in the art. As an example, it can be but not limited to Gr.9 titanium alloy welded pipe strip and Gr.12 titanium alloy welded pipe strip, etc.

[0044] In some embodiments, the preparation method further comprises the following steps: repeating the above steps S20 to S40 until a titanium alloy continuous welded tube of a desired length is prepared.

[0045] In some embodiments, the step of splicing a plurality of titanium alloy strips in S20 includes:

[0046] The strip heads and strip tails of a plurality of titanium alloy strips are cut and polished, and the strip head of one of the titanium alloy strips is spliced ​​with the strip tail of another titanium alloy strip.

[0047] In some specific embodiments, the angle of the cutting position is 30° to 60°, and a groove of 40° to 60° is formed after grinding.

[0048] In some of the embodiments, before splicing multiple titanium alloy strips, the following steps are also included: one end of one of the titanium alloy strips is subjected to forming treatment, second welding, pre-sizing treatment, second induction heating and fine sizing treatment in sequence to obtain a titanium alloy material, and the titanium alloy material includes a tube and a titanium alloy strip.

[0049] Understandably, one end of the titanium alloy strip is subjected to forming, second welding, pre-sizing, second induction heating and precision sizing, so that one end of the strip becomes a tube, while the other end that has not been formed is still a strip, and the tail end of the strip is spliced ​​with the head of another uncoiled titanium alloy strip. Furthermore, the above steps can be completed with the aid of online equipment.

[0050] In some embodiments, the first welding method in S20 includes one or more of metal inert gas shielded welding and argon arc welding with filler wire.

[0051] It can be understood that the first welding is performed in the above manner so that the weld can be penetrated at one time, thereby improving the welding quality of the welding position.

[0052] In some embodiments, the welding speed of the metal inert gas shielded welding is 0.4 m / min~0.7 m / min, the welding current is 200 A~320 A, the flow rate of the front shielding gas is 10 L / min~18 L / min, and the flow rate of the back shielding gas is 5 L / min~12 L / min.

[0053] In some embodiments, after the splicing step and before the first welding step, the following steps are further included:

[0054] Arc-starting plates and arc-extinguishing plates are welded on both sides of the splicing position, and a U-shaped support is installed on the back of the splicing position.

[0055] As an example, the U-shaped support may be selected from a U-shaped groove.

[0056] In some examples, the installation positions of the arc starter plate and the arc extinguisher plate are as follows: Figure 1 shown.

[0057] It can be understood that the material of the arc starting plate and the arc extinguishing plate is the same as that of the titanium alloy strip.

[0058] In some of the embodiments, the welding speed of the swing welding in S30 is 0.3m / min~0.5m / min, the welding current is 180A~280A, the flow rate of the shielding gas is 10L / min~18L / min, the swing width is 5mm~2.5mm, and the swing frequency is 2Hz~4Hz.

[0059] A cover is added to the front of the weld by swing welding, and the cover covers the welding heat affected zone, so that the welding area has excess height as a whole.

[0060] In some specific embodiments, the temperature of the first induction heating in S30 is 935° C. to 950° C. As an example, the temperature of the first induction heating may be, but is not limited to, specific values ​​such as 935° C., 936° C., 937° C., 938° C., 939° C., 940° C., 941° C., 942° C., 943° C., 944° C., 945° C., 946° C., 947° C., 948° C., 949° C. or 950° C., and any value within the range formed by any two of the above values.

[0061] In some specific embodiments, the time of the first induction heating in S30 is 9s-11s; optionally, the time of the first induction heating is 10s.

[0062] In some specific embodiments, the deformation amount of the rolling process in S30 is 50% to 80%. As an example, the deformation amount of the rolling process can be, but is not limited to, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78% or 80%, and any value within the range formed by any two of the above values.

[0063] In some examples, the welds before and after rolling treatment are as follows: Figure 2 shown.

[0064] In some specific embodiments, after the rolling process and before the forming process, the following steps are included: the continuous strip is put into a vertical continuous storage system for storage.

[0065] After completing the rolling process of the previous weld, it is put into the vertical continuous storage system. By releasing the stored coils, time is provided for the coil splicing, so that the forming process of the previous titanium alloy coil and the splicing process of the front and rear titanium alloy coils can be carried out simultaneously.

[0066] In some specific embodiments, the forming process in S40 is multi-pass roll forming, and the deformation amount of each roll forming pass is 10% to 15%. As an example, the deformation amount of each roll forming pass can be but not limited to 10%, 11%, 12%, 13%, 14% or 15%; and any value within the range formed by any two of the above values.

[0067] In some specific embodiments, the forming process in S40 is performed by multi-pass W roller forming.

[0068] In some specific embodiments, the forming process in S40 includes a rough forming process and a fine forming process; the rough forming adopts the uphill deformation bottom line method, and the fine forming adopts a multi-combination seam closing roller. The uphill deformation bottom line method is adopted to reduce the longitudinal deformation stress of the belt edge as much as possible to prevent the belt edge from being torn due to excessive stress; the fine forming adopts a multi-combination seam closing roller to ensure the stable closing of the belt edge.

[0069] In some embodiments, the laser welding in S40 includes one or more of circular scanning galvanometer laser welding and dual-beam laser welding.

[0070] Understandably, in order to avoid the fluctuation of the weld groove gap of the pipe and improve the stability of continuous welding, the spot shape of the circular scanning galvanometer laser is adjusted to improve the adaptability of the laser to the groove.

[0071] In some specific embodiments, a weld tracking system and a welding gun automatic adjustment slide rail are provided on the circular scanning galvanometer laser welding equipment. It is understandable that when the roll forming causes the strip edge groove to change, the weld tracking system can provide real-time feedback to the Y-axis automatic slide rail to adjust the position of the laser head, thereby ensuring welding stability.

[0072] At the same time, a multi-channel argon filling path is arranged at the bottom of the welding chamber, so that argon gas is filled in from the bottom of the welding chamber, and a tail drag hood is arranged for argon gas protection in the high-temperature area of ​​the weld. The double protection measures prevent the high-temperature area of ​​the weld from reacting with elements such as H, O, and N, and at the same time keep a slightly positive pressure state in the welder at all times; the high-temperature area of ​​the weld is matched with a slow-flow drag hood argon gas to cover it, keeping the weld in a silver-white color at all times; the welder is equipped with a dust detection controller and a dust removal channel, which provide real-time feedback on the dust concentration in the welding chamber, and work together with the welder smoke control system to ensure that the dust generation in the welder and the argon gas filling amount always maintain a dynamic balance to avoid oxidation of the weld.

[0073] In some specific embodiments, the welding speed of the circular scanning galvanometer laser welding is 0.8m / min~2m / min, the laser power is 3000W~4500W, the laser tilt angle is 5°~8°, the scanning width of the scanning galvanometer is 0.2mm~2.5mm, and the frequency of the scanning galvanometer is 150Hz~220Hz.

[0074] In some specific embodiments, the welding speed of dual-beam laser welding is 0.6m / min~2m / min, the laser power is 2000W~4500W, the laser tilt angle is 5°~8°, and the light spacing of the dual beams is 1mm~3mm.

[0075] In some specific embodiments, the temperature of the second induction heating in S40 is 600° C. to 800° C. As an example, the temperature of the second induction heating may be, but is not limited to, 600° C., 610° C., 620° C., 630° C., 640° C., 650° C., 660° C., 670° C., 680° C., 690° C., 700° C., 710° C., 720° C., 730° C., 740° C., 750° C., 760° C., 770° C., 780° C., 790° C. or 800° C., and any value within the range formed by any two of the above values.

[0076] In some specific embodiments, the second induction heating time in S40 is 14s-16s; optionally, the second induction heating time is 15s.

[0077] In some specific embodiments, the second induction heating in S40 is performed in a pure argon protective atmosphere.

[0078] It can be understood that the second induction heating is used to eliminate the residual stress in the forming and welding process.

[0079] In some embodiments, the method for preparing the titanium alloy continuous welded tube further includes S50.

[0080] S50: The titanium alloy continuous welded tube is coiled using an automatic coiling machine.

[0081] It can be understood that the above method of the present application can be used to achieve continuous welding of titanium alloy pipes, and the continuous pipe obtained by welding has good mechanical properties.

[0082] Some embodiments of the present application also provide a titanium alloy continuous welded pipe, which is produced using the above-mentioned preparation method.

[0083] In some embodiments, the length of the titanium alloy continuously welded pipe is greater than 10,000 m.

[0084] The present application will be further described below in conjunction with specific examples and comparative examples, but they should not be construed as limiting the scope of protection of the present application. The raw materials involved in the following specific examples, unless otherwise specified, can all be sourced from commercial sources, the instruments used, unless otherwise specified, can all be sourced from commercial sources, and the processes involved, unless otherwise specified, are all conventionally selected by those skilled in the art.

[0085] Example 1

[0086] (1) Uncoiling: A Gr.9 titanium alloy welded tube strip with a width of 115.4±0.1 mm is installed in an uncoiling machine with a driven automatic feed to obtain a titanium alloy strip.

[0087] (2) Material storage: The titanium alloy strip is passed through the shear end welder and the vertical S-type material storage machine, and the material storage length is set to the maximum to provide sufficient time for the subsequent shearing, splicing and welding of other titanium alloy strips.

[0088] (3) Forming treatment: The titanium alloy strip enters the multi-pass W-forming rollers, and overcomes the risk of strip edge rebound or cracking through gradual forming; then it enters the tube billet narrow gap roll bending forming unit to ensure the forming stability of the strip and obtain the tube.

[0089] Among them, the deformation amount of each pass is 12%.

[0090] (4) Second welding: The strip enters the laser welding chamber, and the pipe is welded in an argon-filled environment. A multi-channel argon filling gas path is set at the bottom of the welding chamber, so that argon gas is filled from the bottom of the welding chamber. A tail drag hood is set at the high-temperature area of ​​the weld to provide argon gas protection. Water cooling channels are set around the welding chamber and the cover plate to reduce the heating of the panel by laser reflection.

[0091] The welding laser adopts the circular scanning galvanometer laser welding mode. The laser head is positioned on the servo-driven lead screw, and a weld tracking system is installed in front of the welding point, which can adjust the exact position between the laser spot and the weld in real time. The welding parameters are: welding speed 1.0m / min, laser power 3500W, laser tilt angle 8°, scanning width of the scanning galvanometer is 0.5mm, and the frequency of the scanning galvanometer is 180Hz.

[0092] (5) After welding, the continuous strip is leveled, polished and pre-diametered.

[0093] (6) Second induction heating: Heating to 750 °C in the induction heating coil for 15 s to eliminate residual stress from the forming and welding process. The entire process is carried out in a pure argon protective atmosphere.

[0094] (7) The pipe is precisely sized and straightened, and the resulting continuous pipe is coiled layer by layer using a coiling machine to obtain a titanium alloy material.

[0095] (8) First welding: Use a plate cutter to cut the head of another titanium alloy strip and the tail of the end of the titanium alloy material that has not been formed in step (7). The angle of the shearing position is 30°. The sheared head and tail are spliced ​​and fixed. The arc starter plate and the arc extinguisher plate are fixed on both sides of the splicing position, and a shallow U-shaped support plate with back shielding gas is installed on the back of the splicing position. The weld is filled by melt inert gas shielding welding (MIG welding).

[0096] The MIG welding parameters are as follows: welding speed is 0.4 m / min, welding current is 250 A, shielding gas flow rate is 15 L / min, back shielding gas flow rate is 10 L / min, and the type of shielding gas is argon.

[0097] (9) Oscillating welding: A cover is added to the front of the weld through oscillating welding. The cover covers the heat affected zone of the weld, so that the weld area as a whole has excess height. The excess height of the weld on the back is 1 mm, and the excess height of the weld on the front is 1.5 mm.

[0098] The parameters of the swing welding are as follows: the swing width is 1.5 mm and the swing frequency is 4 Hz.

[0099] (10) The first induction heating and rolling treatment: the weld area is heated to 940 °C using a vertical induction heating coil and the holding time is 15 seconds. The weld excess height is flattened after repeated reciprocating rolling using a weld rolling roller to achieve the same thickness as the coil. The weld deformation is controlled within 75%;

[0100] (11) Cutting: Use a plate cutting machine to cut off the arc-starting plates and arc-extinguishing plates on both sides of the strip coil, clean and polish the strip edges to ensure that the grain size of the weld is equivalent to that of the parent material, and obtain a continuous strip.

[0101] Repeat the above steps (2) to (11) until a Gr.9 titanium alloy continuous welded tube with a specification of Φ38.1*2.2mm is obtained.

[0102] The properties of the titanium alloy continuous welded tube prepared above were tested, and the results showed that the tensile strength was 670 MPa, the yield strength was 545 MPa, the elongation was 15%, the outer diameter tolerance was 38.05~38.15, and the continuous tube length could be 10000 m.

[0103] Example 2

[0104] (1) Uncoiling: A plurality of Gr.12 titanium alloy welded pipe strips with a width of 148.6±0.01 mm are installed in an uncoiling machine with a driven automatic feed to uncoil and obtain a plurality of titanium alloy strips.

[0105] (2) Material storage: The titanium alloy strip is passed through the shear end welder and the vertical S-type material storage machine, and the material storage length is set to the maximum to provide sufficient time for the subsequent shearing, splicing and welding of other titanium alloy strips.

[0106] (3) Forming treatment: The titanium alloy strip enters the multi-pass W-forming rollers, and overcomes the risk of strip edge rebound or cracking through gradual forming; then it enters the tube billet narrow gap roll bending forming unit to ensure the forming stability of the strip and obtain the tube.

[0107] Among them, the deformation amount of each pass is 12%.

[0108] (4) Second welding: The strip enters the laser welding chamber, and the pipe is welded in an argon-filled environment. A multi-channel argon filling gas path is set at the bottom of the welding chamber, so that argon gas is filled from the bottom of the welding chamber. A tail drag hood is set at the high-temperature area of ​​the weld to provide argon gas protection. Water cooling channels are set around the welding chamber and the cover plate to reduce the heating of the panel by laser reflection.

[0109] The welding laser adopts a dual-beam laser welding mode. The laser head is positioned on a servo-driven lead screw, and a weld tracking system is installed in front of the welding point, which can adjust the exact position between the laser spot and the weld in real time.

[0110] The welding parameters are as follows: welding speed 1.2 m / min, laser powers of the dual beams 3200 W and 2500 W respectively, laser tilt angle 8°, and dual beam light spacing 2 mm.

[0111] (5) After welding, the continuous strip is leveled, polished and pre-diametered.

[0112] (6) Second induction heating: Heating to 680 °C in the induction heating coil for 15 s to eliminate residual stress from the forming and welding process. The entire process is carried out in a pure argon protective atmosphere.

[0113] (7) The pipe is precisely sized and straightened, and the resulting continuous pipe is coiled layer by layer using a coiling machine.

[0114] (8) First welding: Use a plate cutter to shear the head of another titanium alloy strip and the tail of the titanium alloy tube that has not been formed in step (7). The shearing angle is 30°. The sheared head and the tail of another titanium alloy strip are spliced ​​and fixed. The arc starter plate and the arc extinguisher plate are fixed on both sides of the splicing position, and a shallow U-shaped support plate with back shielding gas is installed on the back of the splicing position. The weld is filled by melt inert gas shielding welding (MIG welding).

[0115] The MIG welding parameters are as follows: welding speed is 0.5 m / min, welding current is 250 A, shielding gas flow rate is 15 L / min, back shielding gas flow rate is 10 L / min, and the type of shielding gas is argon.

[0116] (9) Oscillating welding: A cover is added to the front of the weld through oscillating welding. The cover covers the heat affected zone of the weld, so that the weld area as a whole has excess height. The excess height of the weld on the back is 1 mm, and the excess height of the weld on the front is 1.5 mm.

[0117] The parameters of the swing welding are as follows: the swing width is 1.5 mm and the swing frequency is 4 Hz.

[0118] (10) The first induction heating and rolling treatment: the weld area is heated to 940 °C using a vertical induction heating coil and the holding time is 12 seconds; the weld excess height is flattened after multiple reciprocating rolling using a weld rolling roller to achieve the same thickness as the coil, and the weld deformation is controlled at 60%;

[0119] (11) Cutting: Use a plate cutting machine to cut off the arc-starting plates and arc-extinguishing plates on both sides of the strip coil, clean and polish the strip edges to ensure that the grain size of the weld is equivalent to that of the parent material, and obtain a continuous strip.

[0120] Repeat the above steps (2) to (11) until a Gr.12 titanium alloy continuous welded tube with a specification of Φ50.8*2.76mm is obtained.

[0121] The properties of the titanium alloy continuous welded tube prepared above were tested, and the results showed that the tensile strength was 512 MPa, the yield strength was 345 MPa, the elongation was 23%, the outer diameter tolerance was 50.70~50.95, and the continuous tube length was 5000 m.

[0122] Example 3

[0123] The method is basically the same as Example 1, except that the parameters of laser welding in step (4) are different. Specifically, the welding speed of the circular scanning galvanometer laser welding is 0.5 m / min, the laser power is 2200 W, the laser tilt angle is 6°, the scanning width of the scanning galvanometer is 0.5 mm, and the frequency of the scanning galvanometer is 200 Hz.

[0124] The properties of the titanium alloy continuous welded tube prepared above were tested. The final titanium alloy continuous welded tube had a specification of ∅38.1*2.2mm, a tensile strength of 660Mpa, a yield strength of 520Mpa, an elongation of 15%, an outer diameter tolerance of 38.06~38.16, and a continuous tube length of 500m.

[0125] Scale 1

[0126] The method is basically the same as Example 1, except that the second welding method in step (4) is tungsten inert gas arc welding; specifically, the parameters of tungsten inert gas arc welding are as follows: welding current is 250A, welding voltage is 12V, and welding speed is 0.7m / min.

[0127] The properties of the prepared titanium alloy continuous welded tube were tested, and the results showed that the tensile strength was 516 MPa, the yield strength was 355 MPa, the elongation was 21%, the outer diameter tolerance was 50.70~50.95, and the continuous tube length was 500 m.

[0128] In Comparative Example 1, since the tungsten electrode burns during the welding process, the welding current needs to be adjusted during the welding process, which easily leads to the situation that the weld is not fully penetrated. And when the welding tungsten needle burns to a certain extent, tungsten impurities will fall into the welding pool, causing the weld to fluctuate. When the continuous welded pipe is produced to about 500 meters, the weld has fluctuated many times, and the tungsten needle is severely burned, making it difficult to continue to operate.

[0129] Comparative Example 2

[0130] It is basically the same as Example 1, except that the first induction heating and rolling treatment are not performed.

[0131] The properties of the prepared titanium alloy continuous welded tube were tested, and the results showed that the tensile strength was 518 MPa, the yield strength was 346 MPa, the elongation was 23%, the outer diameter tolerance was 50.70~50.95, and the continuous tube length was 500 m.

[0132] In comparative example 2, since the weld was not subjected to induction heating and rolling treatment, only the excess height and strip edge were ground, the weld structure and performance were completely different from those of the parent material. However, during the forming process, the strip has to undergo multiple bending deformations, which makes the weld structure present coarse Widmanstatten structure characteristics, and the performance is significantly lower than that of the parent material, which easily leads to tearing of the weld and eventually leads to production interruption. In addition, during the service of the coiled tube, it is subjected to alternating fatigue loads, and the untreated strip head and tail weld positions are also prone to fatigue instability.

[0133] Comparative Example 3

[0134] It is basically the same as Example 1, except that: no cover surface is added to the front side of the weld and no welding process is performed.

[0135] In Comparative Example 3, no weld was added on the front side of the weld to form a positive excess height, resulting in uneven welds on the longitudinal seams of the welded pipe at the contact point, welding defects at the edge of the weld, and failure to prepare a continuous welded pipe of continuous length.

[0136] In summary, the continuous welded pipe prepared by the method of the present application has mechanical properties substantially consistent with those of the parent material, and a continuous welded pipe with a length of 500 m to 10,000 m can be prepared.

[0137] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0138] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a titanium alloy continuous welded tube, characterized in that: The steps include: Uncoiling a plurality of titanium alloy welded pipe strips to obtain a plurality of titanium alloy strips; Splicing the plurality of titanium alloy strips end to end, and performing a first welding process at the splicing positions to form a weld; A cap is formed on the front of the weld by swing welding, and the welding heat affected zone is subjected to first induction heating and rolling treatment in sequence to obtain a continuous strip; the cap covers the welding heat affected zone, and the temperature of the first induction heating is 935°C to 950°C; The continuous strip is subjected to forming treatment, second welding, pre-sizing treatment, second induction heating and precision sizing treatment in sequence to obtain a titanium alloy continuous welded tube; Among them, the second welding method is laser welding, and the second induction heating temperature is 600°C~800°C.

2. The method for preparing a titanium alloy continuous welded tube according to claim 1, characterized in that: The step of splicing a plurality of the titanium alloy strips comprises: The strip heads and strip tails of the plurality of titanium alloy strips are cut and polished, and the strip head of one titanium alloy strip is spliced ​​with the strip tail of another titanium alloy strip.

3. The method for preparing a titanium alloy continuous welded tube according to claim 1, characterized in that: Before splicing the plurality of titanium alloy strips, the method further comprises the following steps: One end of one of the titanium alloy strips is subjected to forming treatment, second welding, pre-sizing treatment, second induction heating and precision sizing treatment in sequence to obtain a titanium alloy material, wherein the titanium alloy material includes a tube and a titanium alloy strip.

4. The method for preparing a titanium alloy continuous welded tube according to claim 1, characterized in that: After the splicing step and before the first welding step, the following steps are also included: Arc-starting plates and arc-extinguishing plates are welded on both sides of the splicing position, and a U-shaped support is installed on the back of the splicing position.

5. The method for preparing a titanium alloy continuous welded tube according to claim 1, characterized in that: The welding speed of swing welding is 0.3m / min~0.5m / min, the welding current is 180A~280A, the flow rate of shielding gas is 10L / min~18L / min, the swing width is 1.5mm~2.5mm, and the swing frequency is 2Hz~4Hz.

6. The method for preparing a titanium alloy continuous welded tube according to any one of claims 1 to 5, characterized in that: The first welding method includes one or more of metal inert gas shielded welding and argon arc wire welding; Optionally, the welding speed of the metal inert gas shielded welding is 0.4m / min~0.7m / min, the welding current is 200A~320A, the flow rate of the front shielding gas is 10L / min~18L / min, and the flow rate of the back shielding gas is 5L / min~12L / min.

7. The method for preparing a titanium alloy continuous welded tube according to any one of claims 1 to 5, characterized in that: Laser welding includes one or more of circular scanning galvanometer laser welding and double beam laser welding; Optionally, the welding speed of the circular scanning galvanometer laser welding is 0.8m / min~1.2m / min, the laser power is 3000W~4500W, the laser tilt angle is 5°~8°, the scanning width of the scanning galvanometer is 0.2mm~2.5mm, and the frequency of the scanning galvanometer is 150Hz~220Hz; Optionally, the welding speed of the dual-beam laser welding is 0.6m / min~1.2m / min, the laser power is 2000W~4500W, the laser tilt angle is 5°~8°, and the light spacing of the dual beams is 1mm~3mm.

8. The method for preparing a titanium alloy continuous welded tube according to any one of claims 1 to 5, characterized in that: The preparation method meets at least one of the following characteristics: (1) The deformation of rolling treatment is 50%~80%; (2) The forming process is multi-pass roller forming, and the deformation of each pass of roller forming is 10%~15%.

9. A titanium alloy continuous welded pipe, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 8.

10. The titanium alloy continuous welded tube according to claim 9, characterized in that: The length of the titanium alloy continuous welded pipe is greater than 10000m.

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