CN115070171B - Welding method for improving strength of N50 armor weld joint - Google Patents
Welding method for improving strength of N50 armor weld joint Download PDFInfo
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- CN115070171B CN115070171B CN202210895417.3A CN202210895417A CN115070171B CN 115070171 B CN115070171 B CN 115070171B CN 202210895417 A CN202210895417 A CN 202210895417A CN 115070171 B CN115070171 B CN 115070171B
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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
- B23K9/00—Arc welding or cutting
- B23K9/32—Accessories
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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
- B23K9/32—Accessories
- B23K9/325—Devices for supplying or evacuating shielding gas
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- Plasma & Fusion (AREA)
- Mechanical Engineering (AREA)
- Arc Welding In General (AREA)
Abstract
The application discloses a welding method for improving the strength of an N50 armor welding seam, which is characterized in that 2 And (3) carrying out self-fusion welding on the N50 armor with the N element content of 0.3-0.5 wt% in the atmosphere of the Ar mixed gas so as to realize the mutual diffusion of metal atoms, thereby obtaining a high-strength welding joint, and being particularly suitable for welding among the N50 armor. The welding method provided by the application can effectively solve the problem of nitrogen loss in the welding process of the nitrogen-containing stainless steel, and when the welding is performed in a protective atmosphere of which the volume percentage is 10% -15% of nitrogen and the volume percentage is 90% -85% of argon, the tensile strength of the welding can reach more than 95% of that of a base metal. The welding method does not need to add other welding wires and does not need to consider the problem of fusion of dissimilar materials. The welding method is simple to realize, and provides a solution for the problem of insufficient weld strength performance caused by the practical application of the N50 armor in the future.
Description
Technical Field
The application relates to the field of armor welding for fusion reactor superconducting magnets, in particular to a welding method for improving the strength of an N50 armor welding line.
Background
The high-field superconducting magnet for the future fusion reactor has the characteristics of strong magnetic field, high current, high load and the like. The armoured cable conductor (cic) is the first conductor to build the fusion reactor magnet, and consists of an outer stainless steel armour and an inner superconducting cable. Armor is the main bearing component in the whole magnet operation process, and under the magnet operation condition of 4.2K ultralow temperature, the armor is required to have high strength and high toughness. Because the length of a single armor is limited, the armor must be butt welded, so the performance of the armor welded joint is crucial, and the tensile strength of the joint is generally required to reach more than 90% of the armor parent metal.
At present, the tensile strength of the optimized novel austenitic stainless steel N50 armor material containing high nitrogen element can reach 1800Mpa at 4.2K, and the application requirements of the future high-field magnet armor material for fusion are met. However, for such high nitrogen added stainless steel armor, conventional tungsten all argon shielded armor welding methods do not allow the weld to meet strength requirements. This is because the conventional welding method causes a problem of loss of nitrogen element in the weld region during the welding process, resulting in a great decrease in the weld strength.
In order to realize the application of the N50 armor in the fusion field, the strength of a welded joint of the N50 armor must be ensured to meet the requirements. How to regulate the solid solubility of nitrogen elements in a welding line area and ensure the welding solid solution strengthening effect of the nitrogen elements becomes a difficult problem which needs to be solved urgently. Therefore, the application of a welding method for improving the welding seam strength of the N50 armor is urgently needed to realize the practical application of the N50 armor and ensure the stable connection of armor joints.
Disclosure of Invention
The application aims to provide a welding method for improving the strength of an N50 armor welding seam. The welding method is used for improving the strength of the N50 armor welding joint and solves the defect of insufficient strength performance of the N50 armor welding joint caused by the traditional armor welding method.
The welding method is realized by adopting the principle that austenitic stainless steel N50 armor containing high nitrogen element is in butt joint connection in a mixed protective atmosphere of nitrogen and argon, the problem of nitrogen element loss of an N50 armor welding seam is solved by regulating and controlling nitrogen partial pressure, and the movement of metal atoms, namely the diffusion capacity among atoms, is enhanced at high temperature, so that a welding joint with high strength and high toughness at 4.2K and room temperature is obtained.
The application is realized by the following technical scheme:
a welding method for improving the weld strength of N50 armor comprises the steps of controlling the mass percentage of C to be less than 0.01%, the mass percentage of Si to be less than 0.4%, the mass percentage of Mn to be 4-6%, the mass percentage of P to be less than 0.005%, the mass percentage of S to be less than 0.0015%, the mass percentage of Cr to be 21-25%, the mass percentage of Ni to be 7.5-15.5%, the mass percentage of Mo to be 1-3%, the mass percentage of N to be 0.3-0.5%, the mass percentage of V to be less than 0.3%, the mass percentage of Nb to be 0.03-0.1%, the mass percentage of Al to be less than 0.01%, and the total mass percentage of Sb, pb, bi, sn, as to be less than 0.015.
A welding method for improving strength of an N50 armor weld joint comprises the following steps:
(1) Firstly, beveling the end part of an N50 armor, wherein the beveling is I-shaped;
(2) Cleaning the end face of the bevel of the N50 armor to obtain a clean and burr-free connecting surface;
(3) Butt-jointing the end faces of grooves of two sections of N50 armor, and fixing and welding by using a clamp;
(4) Pre-conveying protective gas in the N50 armor before welding, and keeping the protective gas conveying after welding, wherein the protective atmosphere comprises N 2 -Ar gas mixture;
(5) The welding starting current is set to be 75A-90A, the arc quenching current is set to be 10A-20A, the tungsten electrode walking delay is 2.5s, and the current slow-down delay is 10s.
In the step (1), the groove is I-shaped, and the end face position of the groove is perpendicular to the axial direction of the armor.
In the step (2), after the surface of the N50 armor is cleaned by using acetone/alcohol, the burr part is polished by using a semicircular file, and then the surface is cleaned by using acetone/alcohol.
In the step (3), the N50 armor is not clamped, the N50 armor can be guaranteed to rotate freely, a gap between the end parts of the butted N50 armor is smaller than 0.1mm, and the distance between the tip ends of the tungsten electrodes and the N50 armor is 1.1-1.3mm.
In the step (4), the mixed gas is 10-15% (volume percent) of nitrogen and 90-85% (volume percent) of argon, and the pre-conveying and delayed conveying time of the protective gas is 20-30s.
Compared with the prior art, the application has the advantages that: the nitrogen is added in the full argon protective atmosphere for welding, so that the problem of nitrogen loss of the N50 armor welding seam can be effectively prevented. The welding method does not need to add other welding wires and does not need to consider the problem of fusion of dissimilar materials; the welding joint obtained by the welding method has high strength, and the joint strength can reach more than 95% of the base material strength at room temperature and 4.2K ultralow temperature. The welding method is easy to realize, and can provide a solution for the problem of insufficient strength at the N50 armor welding joint.
Drawings
In order to more clearly illustrate the embodiments of the application or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the application, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.
Fig. 1 is a schematic diagram of N50 armor welding.
In the figure, a 1-mixed gas channel pipe; 2-N50 armor; 3-tungsten electrode; 4-gap; 5-clamping; 6-a workbench base surface.
Detailed Description
The objects, technical solutions and advantages of the present application will become more apparent by the following detailed description of the present application with reference to the accompanying drawings. It should be understood that the description is only illustrative and is not intended to limit the scope of the application. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the present application.
Fig. 1 is a schematic diagram of N50 armor welding. As shown in figure 1, the end face of one section of N50 armor is in butt joint with the end face of the other section of N50 armor, the butt joint gap 4 is less than or equal to 0.1mm, and the butt joint gaps are respectively fixed on a workbench base surface 6 by clamps 5. And a mixed gas channel pipe 1 with the diameter of 20mm extends into a central hole of the N50 armor 2, and a gas outlet of the pipe is aligned to the joint of the two armor. The tip part of the tungsten electrode 3 used for welding is positioned right above the joint of the armor, and the distance between the tungsten electrode and the armor is kept within the range of 1.1-1.3mm.
In an embodiment of the application, an improved N50 armor weld strength is providedA welding method of the degree. Two N50 stainless steel armors (called N50 armors for short) with diameters of 42mm and wall thicknesses of 2.5mm provided by Zhejiang Jiuy materials technology Co Ltd are utilized 2 An automatic argon tungsten-arc welding connection method of a tungsten electrode 3 with Ar mixed gas as welding protective gas to obtain a high-strength N50 armor 2 weld joint, wherein the N50 stainless steel armor is provided with an N50 armor pipe, the armor pipe is a mixed gas channel pipe 1, and the method comprises the following specific steps of:
(1) Two N50 type stainless steel armor with the diameter of 42mm and the wall thickness of 2.5mm are fixed in a beveling machine, and the ends of the armor are completely cut along the radial direction, namely I-type beveling is carried out;
(2) After the end face of the groove of the N50 armor is cut smoothly, cleaning the end face, polishing by using a semicircular file/sand paper, and checking whether the groove of the section is vertical or not by using a square, thereby obtaining a clean and burr-free connecting surface;
(3) Cleaning the inner and outer walls of the N50 armor by using clean gauze dipped with acetone/alcohol until no greasy dirt and particulate matters are found on the gauze, and drying the end face by using a hot air gun to prevent liquid residue;
(4) Wiping the welding machine head clean by silk cloth, butting the end faces of the two N50 armors 2 with grooves, fixing the two N50 armors on a workbench base surface 6 by using a clamp 5, and ensuring that the armors can rotate freely, wherein a butting gap 4 between the end parts of the two N50 armors 2 is smaller than 0.1mm;
(5) Aligning the tungsten electrode 3 to the butt joint position of the end faces of the armatures, and ensuring that the distance between the tip end position of the tungsten electrode 3 and the outer surface of the N50 armatures 2 is 1.1-1.3mm;
(6) Welding the N50 armor 2, conveying 10-15% of nitrogen and 90-85% of argon shielding gas for 20-30s in an N50 armor pipe (the armor pipe is a mixed gas channel pipe 1) in advance before welding, keeping 20-30s of shielding gas conveying after welding, setting welding starting current to 75A-90A, setting arc extinguishing current to 10A-20A, delaying tungsten electrode walking for 2.5s, delaying current slow drop for 10s, and prohibiting touching a welding piece and a workbench in the welding process;
(7) After welding, visual inspection, go-gauge inspection, X-ray inspection, vacuum helium leakage detection and penetration inspection are carried out on the welded joint, and the welded joint is qualified, and the room temperature and 4.2K tensile test results show that the joint strength reaches more than 95% of the base material strength.
The present application is not described in detail in part as being well known to those skilled in the art. The above examples are merely illustrative of preferred embodiments of the application, which are not exhaustive of all details, nor are they intended to limit the application to the particular embodiments disclosed. Various modifications and improvements of the technical scheme of the present application will fall within the protection scope of the present application as defined in the claims without departing from the design spirit of the present application.
Claims (10)
1. The welding method for improving the strength of the N50 armor weld joint is characterized by comprising the following steps of:
(1) Firstly, beveling the end part of an N50 armor, wherein the beveling is I-shaped;
(2) Cleaning the end face of the bevel of the N50 armor to obtain a clean and burr-free connecting surface;
(3) Butt-jointing the end faces of grooves of two sections of N50 armor, and fixing and welding by using a clamp;
(4) Pre-conveying protective gas in the N50 armor before welding, and keeping the protective gas conveying after welding, wherein the protective atmosphere comprises N 2 -Ar gas mixture;
(5) The welding starting current is set to be 75A-90A, the arc quenching current is set to be 10A-20A, the tungsten electrode walking delay is 2.5s, and the current slow-down delay is 10s.
2. The method of claim 1, wherein the N50 armor material has a nitrogen element content of 0.3wt% to 0.5wt%.
3. The method of claim 1, wherein in step (1), the groove position is perpendicular to the axial direction of the N50 armor.
4. The method according to claim 1, wherein in the step (2), after the surface cleaning by using acetone or alcohol, the burr part is polished by using a half round file, and then cleaned by using acetone or alcohol.
5. The method of claim 1, wherein in step (3), the N50 armor is secured against rotation by a clamp.
6. The method of claim 1 wherein in step (3) the N50 armor face gap is less than 0.1mm.
7. The method of claim 1 wherein in step (3) the tungsten tip is 1.1-1.3mm from the N50 armor.
8. The method of claim 1 wherein in step (4) the N50 armor inner and outer surface welds are simultaneously shielded by a mixed gas.
9. The method according to claim 1, wherein in the step (4), the mixed gas is 10-15% by volume of nitrogen and 90-85% by volume of argon, and the pre-conveying and delayed conveying of the shielding gas are performed for 20-30s.
10. The method of claim 1, wherein the N50 armor material comprises <0.01% by mass of C, < 0.4% by mass of Si, 4% to 6% by mass of Mn, < 0.005% by mass of P, < 0.0015% by mass of S, 21% to 25% by mass of Cr, 7.5% to 15.5% by mass of Ni, 1% to 3% by mass of Mo, 0.3% to 0.5% by mass of N, <0.3% by mass of V, 0.03% to 0.1% by mass of Nb, and the sum of the mass of Al <0.01%, sb, pb, bi, sn and As is <0.015.
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| CN202210895417.3A CN115070171B (en) | 2022-07-26 | 2022-07-26 | Welding method for improving strength of N50 armor weld joint |
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| CN202210895417.3A CN115070171B (en) | 2022-07-26 | 2022-07-26 | Welding method for improving strength of N50 armor weld joint |
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| CN115070171B true CN115070171B (en) | 2023-09-29 |
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2022
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