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Austenitic stainless steel pipe welding operation method

Austenitic stainless steel pipe welding operation method


The welding of the bottom layer of the austenitic stainless steel tube has been carried out by manual tungsten argon arc welding with solid wire welding method, and the tube is filled with Ar to avoid oxidation of the root of the weld to ensure the internal quality of the weld. However, it is difficult to construct Ar in the pipeline, and the amount of Ar in the welding of equipment, tank joints and long pipelines is large, especially the work at height is not conducive to construction, and it is uneconomical to assist many workers. In order to deal with these problems, the quality of the weld is ensured. During the construction, the cored wire is tungsten argon arc welding (TIG), and the filling and sealing surfaces are gas-maintained metal arc welding (MAG).


When welding bottoming, the angle of the welding torch and the angle of the welding wire are the same as those of the carbon steel.


In the welding process, the welding torch should be rotated in a circular arc, the purpose of which is to accelerate the separation of molten iron and molten slag, so that it is easy to see the molten pool. At the same time, the heat input on both sides of the base material groove can be increased to avoid unilateral unfusion. When filling the wire, the wire should be sent to the root of the bath and gently pressed down to ensure the root penetration and root formation.


The wire is fed and removed at a faster frequency than the solid wire. The wire should be removed at intervals such that the end of the wire is in the argon maintenance zone to avoid oxidation of the ends.


When the arc is closed, the arc pit should be filled. If defects such as cracks and shrinkage cavities are found, they should be cleaned and then soldered. To ensure the quality of the weld. When covering the surface welding, pay attention to whether the nozzle and the contact nozzle can be cleaned and cleaned before welding, whether the gas flow rate can be appropriate, clear the bottom layer and control the interlayer temperature.


Due to the gas maintenance welding of the filling and cover layer, the length of the wire extension has a great influence on the stability of the welding process. The longer the wire extension length, the greater the resistance value of the wire, and the wire is overheated to form a condensation. Unstable, severe metal splash, poor weld formation, poor maintenance of the molten pool; long extension of the wire, the welding current increases, the distance between the nozzle and the workpiece is shortened, the welding field of view is unclear, and the weld bead is poorly formed. At the same time, the nozzle will be overheated to form a splash or stick to the nozzle, thereby affecting the gas flow.


In the MAG welding process, the wire extension length is 8~9mm, the welding gun swing amplitude, frequency, speed and edge dwell time are suitable, the action harmonics are divergent, the welding gun angle is adjusted at any time, so that the outer edge of the weld seam is fused and formed beautifully. To ensure the quality of the filling and cover layer.


When welding, the angle of the welding torch should be perpendicular to the axis of the pipe. Since the pipe is round, the angle of the welding torch should be changed at any time, so as to ensure the quality of the welded joint and prevent the occurrence of pores and slag inclusions in the welded joint.


The welding uses a small crescent-shaped swing, and the two sides are slightly stabilized and the intermediate speed is slightly faster, which can prevent the welded weld from protruding and uneven; the upper and lower joints must cross the center line 5 to 10 mm, and the second half. When the ring is filled and the cover is welded to the head, the first half of the arc welding position can be ground to a gentle slope, so that the second half of the joint does not cause defects;


When filling, be careful not to be scratched by the arc at the edge of the groove to prepare the cover layer for welding.


When covering the surface, it should be paused at the edge of the groove to ensure better fusion of the molten pool and the groove. The amplitude and frequency of the welding gun should be compliant during the welding process to ensure the surface size and edge fusion of the surface weld. uniform.


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