CN107052517B - Automatic butt welding process for low-alloy steel and nickel-based alloy dissimilar steel heat exchange tubes - Google Patents
Automatic butt welding process for low-alloy steel and nickel-based alloy dissimilar steel heat exchange tubes Download PDFInfo
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- CN107052517B CN107052517B CN201710313262.7A CN201710313262A CN107052517B CN 107052517 B CN107052517 B CN 107052517B CN 201710313262 A CN201710313262 A CN 201710313262A CN 107052517 B CN107052517 B CN 107052517B
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- 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
- B23K9/00—Arc welding or cutting
- B23K9/02—Seam welding; Backing means; Inserts
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- 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
- B23K9/00—Arc welding or cutting
- B23K9/16—Arc welding or cutting making use of shielding gas
- B23K9/167—Arc welding or cutting making use of shielding gas and of a non-consumable electrode
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- 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
- B23K9/00—Arc welding or cutting
- B23K9/235—Preliminary treatment
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- 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
- B23K2101/00—Articles made by soldering, welding or cutting
- B23K2101/04—Tubular or hollow articles
- B23K2101/06—Tubes
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- 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
- B23K2103/00—Materials to be soldered, welded or cut
- B23K2103/18—Dissimilar materials
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Abstract
The invention discloses a low alloy steel and nickel base alloy dissimilar steel heat exchange tube butt joint automatic welding process, which comprises the following steps: cleaning the heat exchange tube I (1), the heat exchange tube II (3) and the melting ring (2); assembling a heat exchange tube I (1), a heat exchange tube II (3) and a melting ring (2); installing and debugging welding equipment; and setting welding process parameters and starting welding treatment. The automatic welding process for the butt joint of the dissimilar steel heat exchange tubes, provided by the invention, combines specific heat exchange tube specifications, specific welding process parameters and tungsten electrode selection, is suitable for butt welding between the small-diameter large-thick-wall heat exchange tubes, so that the welding process is stable and reliable, the weld joint is formed uniformly and attractively, the weld joint fusion is good, the welding efficiency is high, and the welding quality requirements of the dissimilar steel heat exchange tubes in the high-temperature gas cooled reactor steam generator are met through various nondestructive tests and physical and chemical performance tests.
Description
Technical Field
The invention relates to an automatic butt welding process for dissimilar steel heat exchange tubes of heat exchanger pressure vessel equipment, in particular to an automatic butt welding process for low alloy steel and nickel-based alloy dissimilar steel heat exchange tubes of a steam generator of a fourth generation nuclear power technology, which is represented by a high-temperature gas cooled reactor, a fast neutron reactor and the like.
Background
The structural form of a heat exchange tube of a high-temperature gas cooled reactor steam generator independently designed in China is different from that of a conventional pressurized water reactor and a conventional boiling water reactor. A heat exchange tube body of the high-temperature gas cooled reactor steam generator is in a spiral coil tube form and is divided into a spiral coil low-temperature section low-alloy steel heat exchange tube and a spiral coil high-temperature section nickel-based alloy heat exchange tube according to different working temperatures. The heat exchange tube specification is 19mm in external diameter, 3mm in wall thickness, and the diameter is little and the wall thickness is big.
According to the design requirement of a steam generator, the butt joint of the low-alloy steel heat exchange tube and the nickel-based alloy heat exchange tube needs to meet the radiographic requirement, and meanwhile, the weld forming requirement is severe. In the welding process, the fusion of butt welding seams of the heat exchange tubes needs to be ensured to be good, the two sides of the welding seams are controlled not to be sunken, meanwhile, the welding seams can not exceed the surface of the heat exchange tubes by 0.45mm, and the diameter of a through ball is not less than 12.1mm, so that the welding difficulty is very high for the heat exchange tubes with the specifications. The welding force can not be too strong or weak, so as to meet the requirements of the nuclear power field.
It is worth noting that the heat exchange tubes of the steam generator are dense, the distance between the tube walls of the heat exchange tubes is small, the welding operation space is small, and the difficulty of the welding operation is further increased.
Due to the problems in the prior art, the inventor researches the welding technology of the existing dissimilar steel heat exchange tube so as to research the butt welding process of the low alloy steel and nickel-based alloy dissimilar steel heat exchange tube, wherein the welding process is stable, the welding seam fusion is good, the welding seam is attractive in shape, and the product requirements are met.
Disclosure of Invention
In order to overcome the problems, the inventor of the invention carries out intensive research and designs an automatic welding process suitable for butt joint of low alloy steel with small diameter and large wall thickness and nickel-based alloy dissimilar steel heat exchange tubes.
The invention aims to provide a dissimilar steel heat exchange tube butt welding process, which comprises the following steps:
step 1), cleaning a heat exchange tube I1, a heat exchange tube II 3 and a melting ring 2;
step 2), assembling a heat exchange tube I1, a heat exchange tube II 3 and a melting ring 2;
step 3), installing and debugging welding equipment;
and 4), setting welding process parameters and starting welding treatment.
The invention has the advantages that:
(1) the process provided by the invention adopts the melting ring made of the specific material to butt joint the heat exchange tubes aiming at the material of the heterogeneous heat exchange tubes, so that the performance of the joint of the heat exchange tubes is ensured to meet the product requirement;
(2) the process provided by the invention adopts the melting ring made of a specific material as the butt-joint filling material of the heat exchange tube, and effectively ensures the quality and the formation of the welding seam under the applicable welding process parameters;
(3) the process provided by the invention adopts an automatic TIG welding process, the process can carry out programming control on welding process parameters and processes, the welding process is stable, and good welding seam forming and welding quality can be obtained;
(4) the process provided by the invention can effectively realize the effective welding between the low-alloy steel heat exchange tube at the low-temperature section of the spiral coil and the nickel-based alloy heat exchange tube at the high-temperature section of the spiral coil under the conditions that the heat exchange tubes of the steam generator are dense, the distance between the tube walls of the heat exchange tubes is small, and the welding operation space is small;
(5) the process provided by the invention sets specific welding process parameters and tungsten electrode selection according to specific heat exchange tubes, is suitable for butt welding between dissimilar steel heat exchange tubes with the specifications of 19mm outer diameter, 3mm wall thickness, small diameter and large wall thickness, ensures high welding quality, stable and reliable process, uniform and attractive weld formation, good fusion and high welding efficiency, and meets the requirements of the butt welding quality between the dissimilar steel heat exchange tubes of the nuclear island steam generator through various nondestructive tests and physical and chemical performance tests.
Drawings
FIG. 1 shows a schematic view of an assembly structure according to a preferred embodiment of the present invention;
FIG. 2 is a schematic structural diagram illustrating a butt-welded joint of dissimilar steel heat exchange tubes according to a preferred embodiment of the invention;
FIG. 3 shows a schematic view of welding according to a preferred embodiment of the present invention;
fig. 4 shows a schematic view of a tungsten electrode structure according to a preferred embodiment of the present invention.
The reference numbers illustrate:
1-heat exchange tube I;
2-a melting ring;
3-heat exchange tube II;
4-tungsten pole;
5-tungsten electrode tip taper;
6-tip platform;
7-tooling;
81-arm segment;
82-welding platform.
Detailed Description
The invention is explained in more detail below with reference to the figures and examples. The features and advantages of the present invention will become more apparent from the description.
The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
The invention provides a dissimilar steel heat exchange tube butt welding process, which comprises the following steps:
step 1), cleaning a heat exchange tube I1, a heat exchange tube II 3 and a melting ring 2;
step 2), assembling a heat exchange tube I1, a heat exchange tube II 3 and a melting ring 2;
step 3), installing and debugging welding equipment;
and 4), setting welding process parameters and starting welding treatment.
Step 1), cleaning the heat exchange tube I1, the heat exchange tube II 3 and the melting ring 2.
In a preferred embodiment, the heat exchange tube I1, the heat exchange tube II 3 and the melting ring 2 are cleaned, and the cleanliness is controlled to meet the product requirements.
In a preferred embodiment, the method of cleaning comprises: and (3) polishing the inner wall and the outer wall of the pipe end of the heat exchange pipe within the range of 20-25 mm by using an abrasive belt machine or abrasive paper to remove rust and oil on the inner wall and the outer wall of the pipe end of the heat exchange pipe, so that the pipe end has metallic luster, if the surface of a part to be welded has a defect, removing the defect by using a file, and finally dipping acetone by using non-woven fabric or white cloth to clean the range of at least 20mm of the inner wall and the outer wall of the heat exchange pipe and the whole surface of a melting ring until the non-woven fabric or the white cloth does not change color, wherein the surface of the part to be welded.
In a preferred embodiment, the heat exchange tube I1 is a low alloy steel SA-213T22 heat exchange tube, and the heat exchange tube II 3 is a nickel-based alloy Incoloy800H heat exchange tube.
In a further preferred embodiment, the heat exchange tube I1 has an outer diameter of 19 +/-0.10 mm and a wall thickness of 3 +/-0.10 mm; the outer diameter of the heat exchange tube II 3 is 19 +/-0.05 mm, and the wall thickness is 3 +/-0.10 mm; preferably, the heat exchange tube I1 and the heat exchange tube II 3 have the same specification.
IN a preferred embodiment, the melting ring 2 is made of annular IN82 (AWS class number) material, and the melting ring 2 is used as a filling material for butt joint of the dissimilar heat exchange tubes I1 and II 3, so that the two heat exchange tubes can be effectively combined during welding, and good weld fusion is realized. The melting ring 2 is matched with the heat exchange tube, so that the operation of conveying welding wires during welding is omitted, the influence of manual operation is reduced, the difficulty of welding operation is reduced, and the control on the welding quality is facilitated.
And step 2), assembling the heat exchange tube I1, the heat exchange tube II 3 and the melting ring 2.
In the invention, as shown in figure 1, a tool 7 is adopted to assemble and position a heat exchange tube I1, a heat exchange tube II 3 and a melting ring 2. The tool 7 is an axial centering and fixing device for butt welding of small-diameter pipes, and comprises two pressure plates for clamping the small-diameter pipes to be welded and other related components.
In the invention, the pipe ends at one side of the heat exchange pipe I1 and the heat exchange pipe II 3 can be subjected to cleaning, subsequent fixing and welding in the step 1 after grooves are processed in advance; or the groove is not processed, and the fixing and welding are directly carried out after the cleaning treatment. By adopting any mode and matching with the welding process disclosed by the invention, high-quality welding can be realized.
In a preferred embodiment, the pipe ends at one side of the heat exchange pipe I1 and the heat exchange pipe II 3 can be assembled and welded after being beveled in advance.
At the moment, for the structure of the matched melting ring 2, the outer walls of one ends of the heat exchange tube I1 and the heat exchange tube II 3 are processed into stepped single-side grooves, and the specifications of the two single-side grooves are the same. The stepped single-side groove comprises an inclined groove surface, the angle formed by the groove surface and the axis of the pipe hole is 30-90 degrees, and the depth of the groove is not less than the wall thickness of the melting ring 2.
At this time, the assembling method is as follows: firstly, one pressing plate of the tool 7 is used for clamping any heat exchange tube, the pressing plate is adjusted to a set position at the bevel end, then the other pressing plate is used for clamping another heat exchange tube, the melting ring 2 is arranged at the bevel of the heat exchange tube, the bevel of the heat exchange tube I1 is opposite to that of the heat exchange tube II 3, and the melting ring 2 falls into the two butted bevels. The assembled structure is shown in fig. 2.
In the invention, the welding equipment can be matched with the tool 7 for clamping, so that a welding head of the welding equipment faces the melting ring 2, the welding equipment is fixed on the tool 7 during welding, and the rotation center of the welding head drives the tungsten electrode to rotate and weld around the melting ring 2, therefore, the distance from two pressure plates of the tool 7 to the beveled ends of two heat exchange tubes respectively is closely related to the position of the welding head relative to the melting ring 2. And according to the specifications of the melting ring 2 and the welding head, the distance from the pressure plate to the beveled end of the heat exchange tube is correspondingly adjustable.
In another preferred embodiment, the heat exchange tube I1 and the heat exchange tube II 3 are not provided with grooves and are directly assembled and welded.
At this time, the assembling method includes: a pressing plate of the tool 7 is arranged at the end part of one side of the heat exchange tube I1, the pressing plate is adjusted to a set position of the end of the heat exchange tube, the heat exchange tube II 3 is assembled by the other pressing plate, the melting ring 2 is arranged between the two heat exchange tubes, and the heat exchange tubes on two sides are tightly matched with the melting ring 2. The assembled structure is shown in fig. 2.
The positions of the heat exchange tubes at two sides and the melting ring 2 are adjusted through the tool 7, so that the heat exchange tubes are coaxial with the melting ring 2.
And 3), installing and debugging the welding equipment.
In a preferred embodiment, welding equipment is automatic argon arc welding (TIG) welding equipment, welding equipment can program and save welding process parameter, realizes automatic control to electric current, voltage etc. in welding process, can also realize functions such as data real time monitoring among the welding process, has effectively improved welding efficiency, reduces the influence of artificial factor to the welding seam quality among the welding process. Preferably, the welding equipment is automatic pulse argon arc welding equipment, pulse heating is performed in the welding process, the heat input amount is concentrated in the welding process, the arc stiffness is good, the welding energy is favorably adjusted, the annular welding seam is formed uniformly, the welding process is stable, and the automatic pulse argon arc welding equipment is particularly suitable for butt joint among heat exchange tubes with large welding difficulty, small diameter and large wall thickness and sensitive to welding process parameters.
In a preferred embodiment, because the butt joint between the heat exchange tubes needs to be welded annularly, the welding head of the welding equipment can be clamped with the tool 7 in a matched manner, and the welding head can be conveniently controlled during rotary welding.
As shown in fig. 3, the welding head is an L-shaped welding head, and includes an arm segment 81 and a welding platform 82. After assembly, the arm section 81 is parallel to the heat exchange tube, and the welding platform 82 is sleeved outside the heat exchange tube. The welding head with the structure occupies small space and can weld in the dense space of the heat exchange tube of the steam generator.
The welding head includes a tungsten electrode that is secured within the welding platform 82. The tungsten electrode acts as an electrode to conduct current, ignite the current, and maintain proper combustion of the arc. The specifications of the tungsten electrode are closely related to the weldment thickness and the welding current magnitude, while the shape of its end has a large influence on the arc stability and weld formation. According to the materials and specifications of the heat exchange tube and the melting piece, the tungsten electrode with a specific model is selected based on the welding requirements of the heat exchange tube with a small diameter and a large wall thickness and in combination with set technological parameters.
As shown in fig. 4, the tungsten electrode includes a tungsten electrode rod 4, a tungsten electrode end cone 5, and a tip platform 6 disposed on the tungsten electrode end cone 5. The shape of the end of the tungsten electrode directly influences the emission capability of electrons of the tungsten electrode, thereby influencing the penetration effect of the welding seam. The taper angle of the end part cone of the tungsten electrode is increased, and the arc column is diffused, so that the fusion depth is reduced, and the fusion width is increased; with the reduction of the cone angle, the arc column diffusion tendency is reduced, the fusion depth is increased, and the fusion width is reduced. The size of a platform at the tip of the tungsten electrode is increased, and the arc column is diffused, so that the melting depth is reduced; the platform at the tip of the tungsten electrode is too small in size, and the burning loss of the tungsten electrode is serious.
According to the invention, the diameter of the tungsten pole rod 4 is 1.6 mm or 2.4mm, the cone angle of the tungsten pole end part cone 5 is 25-30 degrees, the diameter of the tip platform 6 is 0.35-0.40 mm, the circle center of the tip platform 6 is collinear with the axis of the tungsten pole end part cone 5, and the axis of the tungsten pole end part cone 5 is collinear with the axis of the tungsten pole rod 4.
Different types of tungsten electrodes have different electron emission capabilities, different formed arc voltages and different weld penetration depths, different pollution resistance capabilities and different service lives. Preferably, the tungsten electrode is a thorium tungsten electrode. The thorium tungsten electrode has high electron emissivity, increases the allowable current range, reduces the no-load voltage, improves the arc striking and stabilizing performance, and is more suitable for welding operation in the invention compared with other tungsten electrodes.
In a preferred embodiment, the welding head is installed, so that after the welding head is installed in cooperation with the tool 7, a tungsten electrode on the welding head points to the middle position of the melting ring 2 in the length direction of the heat exchange tube, namely, during welding, the tungsten electrode is aligned to the middle position of the melting ring 2 for welding.
Adjusting the distance between a tungsten electrode on a welding head and the melting ring 2, wherein when the distance between the tungsten electrode and the melting ring 2 is too small, the outer side of a welding seam is easy to form a depression, and the tungsten electrode is easy to burn to cause tungsten inclusion in the welding seam; when the distance is too large, the stability of welding electric arc cannot be ensured, and the welding quality is influenced; therefore, the distance between the tungsten electrode tip platform 6 and the outer wall of the melting ring 2 is controlled to be 1.5-2 mm in the radial direction of the melting ring 2.
Before the dissimilar steel butt welding is implemented, the welding equipment is installed and debugged, the equipment is checked, the correct connection of all lines and the normal functions are ensured, the welding gas and the like meet the requirements, and welding process parameters are programmed and stored in an operation box of a welding device.
And 4), setting welding process parameters and starting welding treatment.
Welding is carried out according to the welding process parameters and the operation requirements of the invention. According to the material quality, specification and welding shape of two different steels, the optimized welding process parameters are obtained through repeated setting and experiments, and the welding process parameters are as follows: the base value current is 20-45A, the peak current is 40-90A, the pulse frequency is 2-2.5 Hz, the pulse width ratio is 40% -50%, the welding voltage is 15-33V, the welding speed is 80-105 mm/min, the front protective gas is helium (the purity is more than or equal to 99.995%), the gas flow is 8-20L/min, the back protective gas is argon (the purity is more than or equal to 99.997%), and the gas flow is 10-40L/min.
The welding current is the most main parameter for determining the weld penetration, and is large, so that the penetration is increased; when the welding current is too large, the defects of humping, burning-through and the like are easily formed, and the phenomena of undercut, poor weld joint forming and the like can also be caused; the current is small, the welding seam forming is difficult to control, the defects of incomplete fusion, incomplete penetration and the like are easily formed, and meanwhile, the small current causes the reduction of the production rate and the waste of shielding gas. According to the invention, the base current is selected to be 20-45A, and the peak current is selected to be 40-90A, so that good weld forming and weld fusion are achieved.
The front shielding gas is gas sprayed by the welding head to protect a welding part, and influences the conditions of welding arc space shape, arc energy density, melting characteristics of the melting ring 2, welding process splashing and the like. Through research and verification, helium is selected as the front protective gas, so that the arc space shape and the arc energy density can be stabilized, the weld forming is improved, the splashing is reduced, the defects are eliminated and prevented, and the weld quality is improved.
The back protective gas is the protective gas introduced into the butted heat exchange tubes, and argon is selected. The argon gas has high density, is not easy to float and dissipate in use, and can form a stable airflow layer after flowing out.
When the flow of the shielding gas is suitable, the molten pool is stable, the surface is bright without slag and oxidation traces, and the weld joint is attractive in shape; when the flow is not suitable, slag exists on the surface of the molten pool, and the welding strength is unqualified. The flow rate of the front shielding gas is 8-20L/min, and the flow rate of the back shielding gas is 10-40L/min.
In a preferred embodiment, the welding angle of the tungsten electrode directed to the melting ring 2 is set to ensure the quality of the weld fusion. The preferred tungsten electrode extension length of the invention is 4-5 mm, the distance between the tip platform 6 of the tungsten electrode and the outer wall of the melting ring 2 in the radial direction of the melting ring 2 is 1.5-2 mm, and the welding angle of the tungsten electrode vertical or nearly vertical to the central axis of the melting ring 2, namely the tungsten electrode pointing to the melting ring 2, is 90 +/-5 degrees.
In a preferred embodiment, as shown in fig. 3, the axis of the assembled heat exchange tube i 1, heat exchange tube ii 3 and melting ring 2 is vertically fixed, the tungsten electrode is vertical to the central axis of the heat exchange tube, and the rotation center in the welding platform 82 of the welding head drives the tungsten electrode to rotate at the transverse welding position to automatically weld the heat exchange tube. The welding of the heat exchange tubes at the two sides of the melting ring 2 is completed by heating the melting ring 2.
The welding process parameters and the operation requirements of the invention are adopted to carry out the butt welding of the dissimilar steel heat exchange tubes, so that good weld forming and weld fusion can be achieved, and the result meets the welding quality requirements of the heat exchange tubes of the high-temperature gas cooled reactor steam generator through various nondestructive tests and physical and chemical performance tests.
After the welding is carried out by adopting the automatic welding process for the butt joint of the dissimilar steel heat exchange tubes, provided by the invention, the detection result is as follows:
visual detection: the welded seam is uniform and full, no visible defect exists, and the outer wall is not sunken;
detecting the inner diameter of a pipe hole at a welding seam: the bulge of the outer wall is not more than 0.45mm, and the diameter of the through ball is not less than 12.1 mm;
liquid permeation: the test result is not displayed, which indicates that no liquid leaks;
rod anode ray detection (RT): the inner wall is not sunken; no crack, undercut, no fusion and no penetration welding; the circular display size is less than 0.6mm, and the number of the circular display sizes is not more than 4;
stretching at room temperature: the tensile strength is more than or equal to 415 MPa;
high temperature (550 ℃) stretching: the tensile strength is more than or equal to 322 MPa;
surface bending and back bending tests: the bending angle is 180 degrees, and no crack or defect with the length of more than 3mm exists on the stretching surface in any direction;
metallographic test: the parent metal, the welding seam and the heat affected zone have no defects such as air holes, cracks and the like.
Examples
According to the welding process provided by the invention, a low-alloy steel SA-213T22 heat exchange tube and a nickel-based alloy Incoloy800H heat exchange tube IN a high-temperature gas cooled reactor steam generator are welded, the specifications of the two heat exchange tubes are phi 19 multiplied by 3mm, the minimum tube wall spacing of the heat exchange tubes is 41mm, and the filling material is an IN82 melting ring, which is as follows:
step 1), before welding, polishing the end of a low-alloy steel SA-213T22 heat exchange tube and a nickel-based alloy Incoloy800H heat exchange tube and the to-be-welded part of an IN82 fusion ring until the metal luster appears, and dipping white non-woven fabric into acetone to wipe the non-woven fabric until the non-woven fabric is not discolored;
step 2), installing a pressing plate of the heat exchange tube welding tool 7 at the tube end of any heat exchange tube, and adjusting the relative position of the tool 7 and the tube end; assembling another heat exchange tube and a melting ring, adjusting the positions of the heat exchange tubes on the two sides and the melting ring through a tool 7, ensuring the coaxiality of the heat exchange tubes on the two sides and the melting ring, and ensuring the close fit of the heat exchange tubes on the two sides and the melting ring;
step 3), a welding head of the welding equipment is matched and clamped with the tool 7; in the length direction of the heat exchange tube, a tungsten electrode on a welding head points to the middle position of the melting ring; in the radial direction of the melting ring, the distance between the tungsten electrode and the outer wall of the melting ring is controlled to be 1.5 mm. Selecting a thorium tungsten electrode, wherein the diameter of the tungsten electrode is 1.6 mm, the conical angle of a cone at the end part of the tungsten electrode is 30 degrees, and the diameter of a tip platform is 0.35 mm;
and 4), welding according to the welding parameters and the operation requirements of the process, wherein the parameters of the welding process adopted by the process are selected as follows: the base current is 20-45A, the peak current is 40-90A, the pulse frequency is 2 Hz, the pulse width ratio is 40%, the welding voltage is 23V, the welding speed is 80mm/min, the front-side protective gas is helium (with the purity of 99.997%), the gas flow is 10L/min, the back-side protective gas is argon (with the purity of 99.999%), and the gas flow is 20L/min. When in welding, the tungsten electrode is vertical to the length direction of the heat exchange tube. And a welding program is edited in advance and stored in the welding equipment control box, and the welding process is controlled by the welding program.
The welded product was tested as follows:
visual detection: the welded seam is uniform and full, no visible defect exists, and the outer wall is not sunken;
detecting the inner diameter of a pipe hole at a welding seam: the bulge of the outer wall is 0.15mm, and the diameter of the through ball is 12.7 mm;
liquid permeation: the test result is not displayed, which indicates that no liquid leaks;
rod anode ray detection (RT): the inner wall is not sunken; no crack, undercut, no fusion and no penetration welding;
stretching at room temperature: tensile strength 530 MPa;
high temperature (550 ℃) stretching: the tensile strength is 358 MPa;
surface bending and back bending tests: the bending angle is 180 degrees, and no crack or defect with the length of more than 3mm exists on the stretching surface in any direction;
metallographic test: no defects such as pores and cracks were observed.
The result shows that the welded product prepared by the embodiment meets the above inspection standard, and meets the welding quality requirement of the low-alloy steel SA-213T22 heat exchange tube and the nickel-based alloy Incoloy800H heat exchange tube in the high-temperature gas cooled reactor steam generator.
In the description of the present invention, it should be noted that the terms "upper", "inner", "outer", etc. indicate the orientation or positional relationship based on the operation state of the present invention, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation and operation, and thus, should not be construed as limiting the present invention.
The invention has been described in detail with reference to the preferred embodiments and illustrative examples. It should be noted, however, that these specific embodiments are only illustrative of the present invention and do not limit the scope of the present invention in any way. Various modifications, equivalent substitutions and alterations can be made to the technical content and embodiments of the present invention without departing from the spirit and scope of the present invention, and these are within the scope of the present invention. The scope of the invention is defined by the appended claims.
Claims (4)
1. An automatic butt welding process for dissimilar steel heat exchange tubes is characterized by comprising the following steps:
step 1), cleaning a heat exchange tube I (1), a heat exchange tube II (3) and a melting ring (2),
polishing the inner wall and the outer wall of the pipe end of the heat exchange pipe within the range of 20-25 mm by using an abrasive belt machine or abrasive paper to remove rust and oil on the inner wall and the outer wall of the pipe end of the heat exchange pipe so that the pipe end of the heat exchange pipe has metallic luster, if the surface of a part to be welded has a defect, cleaning the defect by using a file, and finally cleaning the range of at least 20mm of the inner wall and the outer wall of the heat exchange pipe and the whole surface of a melting ring by dipping acetone by using non-woven fabrics or white cloth until the non-woven fabrics or;
the heat exchange tube I (1) is a low alloy steel SA-213T22 heat exchange tube, and the heat exchange tube II (3) is a nickel-based alloy Incoloy800H heat exchange tube;
the melting ring (2) is annular IN82 material;
the outer diameter of the heat exchange tube I (1) is 19 +/-0.10 mm, the wall thickness is 3 +/-0.10 mm, and the wall thicknesses of the heat exchange tube I (1) and the heat exchange tube II (3) with the outer diameter of 19 +/-0.05 mm are equal;
step 2), assembling a heat exchange tube I (1), a heat exchange tube II (3) and a melting ring (2);
assembling a heat exchange tube I (1), a heat exchange tube II (3) and a melting ring (2) by adopting a tool (7), wherein the tool (7) comprises two pressing plates for clamping the heat exchange tube to be welded;
step 3), installing and debugging welding equipment;
a welding head of the welding equipment is matched and clamped with a tool (7), wherein the welding head is an L-shaped welding head and comprises an arm section (81) and a welding platform (82); after the assembly is finished, the arm section (81) is parallel to the heat exchange tube, and the welding platform (82) is sleeved outside the heat exchange tube;
the welding head comprises a tungsten electrode which is fixed in the welding platform (82); the rotation center in the welding platform (82) of the welding head drives the tungsten electrode to rotate at the transverse welding position to automatically weld the heat exchange tube;
the tungsten electrode is a thorium tungsten electrode;
the tungsten electrode comprises a tungsten electrode rod (4), a tungsten electrode end cone (5) and a tip platform (6) arranged on the tungsten electrode end cone (5),
the diameter of the tungsten pole rod (4) is 1.6 mm or 2.4mm, the cone angle of the tungsten pole end part cone (5) is 25-30 degrees, the diameter of the tip platform (6) is 0.35-0.40 mm, the circle center of the tip platform (6) is collinear with the axis of the tungsten pole end part cone (5), and the axis of the tungsten pole end part cone (5) is collinear with the axis of the tungsten pole rod (4);
step 4), setting welding process parameters and starting welding treatment;
the welding process parameters are as follows: the method comprises the following steps of (1) setting a base value current of 20-45A, a peak current of 40-90A, a pulse frequency of 2-2.5 HZ, a pulse width ratio of 40% -50%, a welding voltage of 15-33V, a welding speed of 80-105 mm/min, a front-side protective gas of helium, a purity of more than or equal to 99.995%, a gas flow rate of 8-20L/min, a back-side protective gas of argon, a purity of more than or equal to 99.997%, and a gas flow rate of 10-40L/min;
in the length direction of the heat exchange tube, a tungsten electrode on a welding head points to the middle position of the melting ring (2);
in the radial direction of the melting ring (2), controlling the distance between the tungsten electrode tip platform (6) and the outer wall of the melting ring (2) to be 1.5-2 mm;
setting the welding angle of the tungsten electrode pointing to the melting ring (2), so that the welding angle of the tungsten electrode pointing to the melting ring (2) is 90 +/-5 degrees;
stretching at room temperature: the tensile strength is more than or equal to 415 MPa;
stretching at the high temperature of 550 ℃: the tensile strength is more than or equal to 322 MPa.
2. The welding process according to claim 1, wherein in the step 2), the pipe ends at one side of the heat exchange pipe I (1) and the heat exchange pipe II (3) are directly assembled without processing grooves;
the assembling method comprises the following steps: a pressing plate of the tool (7) is arranged at the end part of one side of the heat exchange tube I (1), the pressing plate is adjusted to a set position of the tube end, the heat exchange tube II (3) is assembled by the other pressing plate, the melting ring (2) is arranged between the two heat exchange tubes, and the heat exchange tubes on the two sides are tightly matched with the melting ring (2).
3. The welding process according to claim 1, wherein in the step 2), the positions of the heat exchange tubes on two sides of the melting ring (2) and the melting ring (2) are adjusted through the tool (7), so that the heat exchange tubes I (1) and II (3) are coaxial with the melting ring (2).
4. The welding process according to one of claims 1 to 3, wherein the detection result after welding of the dissimilar steel heat exchange tube is as follows:
a. visual detection: the welded seam is uniform and full, no visible defect exists, and the outer wall is not sunken;
b. detecting the inner diameter of a pipe hole at a welding seam: the bulge of the outer wall is not more than 0.45mm, and the diameter of the through ball is not less than 12.1 mm;
c. liquid permeation: the test result is not displayed, which indicates that no liquid leaks;
d. detecting the rod anode rays: the inner wall is not sunken; no crack, undercut, no fusion and no penetration welding; the circular display size is less than 0.6mm, and the number of the circular display sizes is not more than 4;
e. surface bending and back bending tests: the bending angle is 180 degrees, and no crack with the length of more than 3mm exists on the stretching surface in any direction;
f. metallographic test: the parent metal, the welding seam and the heat affected zone have no air holes or crack defects.
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| CN107350601B (en) * | 2017-08-29 | 2020-02-21 | 南京中船绿洲机器有限公司 | Welding process for dissimilar metal materials in offshore operation equipment |
| CN108057943A (en) * | 2017-12-20 | 2018-05-22 | 鲁西工业装备有限公司 | A kind of automatic submerged-arc welding method of Langaloy and low-alloy steel |
| CN108555525B (en) * | 2018-04-17 | 2020-07-28 | 南京金创有色金属科技发展有限公司 | Welding repair process for adsorption desulfurization regenerator |
| CN108581141A (en) * | 2018-05-09 | 2018-09-28 | 江苏大学 | A kind of welding method of high temperature gas cooled reactor heat-transfer pipe dissimilar materials |
| CN108459086B (en) * | 2018-05-21 | 2023-10-24 | 哈电集团（秦皇岛）重型装备有限公司 | Manual ultrasonic inspection method for large thick-wall dissimilar metal weld joint |
| CN108994430B (en) * | 2018-09-05 | 2020-12-11 | 中国核工业二三建设有限公司 | Welding method of nickel-based alloy steel and carbon steel dissimilar material pipeline |
| CN110508909B (en) * | 2019-08-07 | 2021-07-09 | 哈电集团（秦皇岛）重型装备有限公司 | Welding system and method for stainless steel pipe butt joint automatic superposition pulse single-pass welding |
| CN112191999A (en) * | 2020-09-21 | 2021-01-08 | 东方电气集团东方锅炉股份有限公司 | Fillet weld structure of nickel-based small pipe and alloy steel header and welding process |
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| US3800116A (en) * | 1970-12-29 | 1974-03-26 | Sumitomo Metal Ind | Apparatus for automatically welding pipe joints for cylindrical members such as steel pipe piles |
| JPS5542148A (en) * | 1978-09-21 | 1980-03-25 | Mitsubishi Heavy Ind Ltd | Inconel welding method of dissimilar material joint |
| CN201950378U (en) * | 2011-01-12 | 2011-08-31 | 哈电集团（秦皇岛）重型装备有限公司 | Melting ring for butt welding of dissimilar steel heat exchange tube |
| CN103170768B (en) * | 2011-12-21 | 2015-12-02 | 哈电集团（秦皇岛）重型装备有限公司 | Straight pipe with small diameter Butt welding device |
| CN105081538B (en) * | 2015-08-25 | 2017-04-19 | 哈电集团（秦皇岛）重型装备有限公司 | Process for automatically welding small-specification thin-walled tube and small-holed axle tube plate |
| CN205342335U (en) * | 2016-01-05 | 2016-06-29 | 哈电集团（秦皇岛）重型装备有限公司 | A axial alignment and fixing device for narrow tube butt welding usefulness |
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