[0035] Example one
[0036] The embodiment of the present invention provides a single-pole magnetron electroslag surfacing method for nuclear power plants, which is applied to a magnetron electroslag surfacing device for surfacing corrosion-resistant layers of large vessels in nuclear power plants. Please refer to figure 1 , The strip electrode electroslag surfacing welding device includes: fusion welding power source 1, strip electrode welding material 2, strip electrode feeding module 3, contact tip 4, single magnetron module 5 and magnetron power source 6; the surface of large container 7 is laid There are flux 8 and slag 9; figure 2 As shown, the electrode electroslag surfacing method includes the following steps:
[0037] S1. Connect the positive electrode of the welding power source 1 with the contact tip 4, so that the strip electrode 2 connected to the contact tip 4 is charged, and the strip electrode is fed into the module 3 to be charged The tape electrode 2 is delivered to the surface of the large container 7;
[0038] S2. Connect the negative electrode of the fusion welding power source 1 with the large container 7 to form a current loop when the charged strip welding material 2 contacts the surface of the large container 7, so that the slag 9 is conductive And generate resistance heat to melt the strip electrode 2, the flux 8 and part of the surface layer of the large container 7 to form a molten pool;
[0039] S3. Supply power to the single magnetron module 5 through the magnetron power supply 6 so that the single magnetron module 5 generates a magnetic field, thereby preventing undercutting during the process of cooling the molten pool to form the weld bead 10 Wherein, the installation position of the single magnetron module 5 can be adjusted to realize the electrode electroslag surfacing on the attachment area of the boss of the large container 7. Wherein, the magnetron module 5 forms a magnetron electrode when it is energized, and the magnetron electrode is an N pole.
[0040] In the specific implementation process, in terms of parameters, the difference between single magnetron and double magnetron is mainly the difference in magnetron current. Under reasonable single magnetron current and reasonable welding process parameters, no undercut defects can be obtained. And the performance meets the required surfacing weld, so the single magnetron can achieve the same effect as the double magnetron in preventing undercut. In this embodiment, the welding process parameters provided below can obtain a surfacing weld with good performance, and the weld has no undercut defects:
[0041] 1) The magnetron current delivered by the magnetron power supply 6 to the magnetron module 5 is 2.0-2.1A;
[0042] 2) The welding current provided by the welding power source 1 is 1000-1100A, and the welding voltage is 23-26V;
[0043] 3) The welding speed of the electrode electroslag surfacing welding device is 190-230 mm/min.
[0044] Austenitic stainless steel has good plasticity, toughness, weldability, corrosion resistance and non-magnetic or weak magnetic properties. It has good corrosion resistance in oxidizing and reducing media. Nickel-based corrosion resistant alloys have excellent stress corrosion resistance in high temperature environments containing water. In this scheme, in order to improve the corrosion resistance of the large nuclear power plant container surface, a certain thickness of stainless steel or nickel-based alloy is surfacing welded on the surface of the large nuclear power plant container. The strip welding material used in the unipolar magnetron strip electrode electroslag surfacing device 2Using 60mm×0.5mm stainless steel welding strip or 60mm×0.5mm nickel-based alloy welding strip. That is, the single-pole magnetron electroslag surfacing device of this scheme is suitable for 60mm×0.5mm stainless steel electroslag surfacing and 60mm×0.5mm nickel-based alloy electroslag surfacing.
[0045] In the surfacing test process of the first embodiment, use such as figure 1 The unipolar magnetron electroslag surfacing device shown image 3 The base material 31 shown is surfacing welding, the welding current ranges from 1000A to 1100A, the preheating temperature is controlled between 125°C and 150°C, and the interlayer temperature is controlled within 225°C. in image 3 Among them, the base material 31 used is SA508Gr3Cl2 low-alloy steel (which is the same material as the large-scale nuclear power plant container), and the test plate length (a) × width (b) × height (c) is 410mm × 280mm × 100mm; strip welding material 2 It is an Inconel52M nickel-based alloy, the size is 60×0.5mm, the flux 8 is INCOFLUXESS2, and the welding method is horizontal electrode electroslag surfacing. The schematic diagram of surfacing welding bead 32 is still as follows image 3 As shown, the overlap between each bead is 7-9mm. After the surfacing welding is completed, post heat treatment is carried out. The post heat treatment process: heat the base material 31 and the weld bead 32 to a temperature range of 250°C to 300°C for 4 hours. After post-heating is completed, post-welding stress-relieving heat treatment is performed. Post-welding stress-relieving heat treatment process: heat the base material 31 and the weld bead 32 to a temperature range of 595℃~610℃ for 16.5 hours. The non-destructive testing during the entire welding process includes: (1) Visual inspection and dimensional inspection of the surface to be surfacing; (2) MT inspection of the surface to be surfacing; (3) Visual inspection and dimensional inspection of the surfacing layer after welding; (4) PT inspection of surfacing layer after welding; (5) UT inspection of surfacing layer after welding; (6) PT inspection of surfacing layer after heat treatment; (7) UT inspection of surfacing layer after heat treatment; (8) Macro metallographic sample PT an examination. After the final heat treatment, the welded joints are sampled to analyze the deposited metal composition, hardness test (surfacing layer, heat-affected zone, base metal), and macroscopic metallographic inspection perpendicular to the surfacing direction (surfacing layer, heat-affected zone, mother metal). Material), microscopic metallographic inspection (surfacing layer, heat-affected zone) perpendicular to the surfacing direction, guided bending test. The analysis and testing results show that all the results meet the requirements, that is, it can meet the forming and performance requirements of the surfacing weld.
[0046] For the question of how to improve the accessibility of the welding gun, such as figure 1 As shown, the single magnetron module 5 of the single-pole magnetron electroslag surfacing welding device is installed on one side in the width direction of the electrode welding material 2, and the magnetron module 5 occupies a certain space position. Welding direction ( figure 1 The direction indicated by the middle arrow) is perpendicular to the width of the strip welding material 2. Therefore, during the surfacing process, the single magnetron module 5 can be adjusted to the left or right of the contact tip 4 according to the position of the boss, so as to realize the alignment of the boss The nearby area is implemented with electrode surfacing to improve the welding accessibility of the electrode electroslag surfacing device.
