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High-tech argon welding

Many products used in everyday life and in industry are made of metals and their alloys. To obtain a durable and high-quality all-in-one connection of metal products, the best method is welding by melting. Among the methods that are comparatively cheap and which make it possible to obtain a decent quality of the welded seam, argon welding can be called. This is one of the types of electric arc welding. It is carried out by an arc burning between non-consumable (more often - tungsten) electrode and metal workpiece. The electrode is fixed in the burner, and the filler material supplied to the melting zone from the outside is not part of the electrical circuit. The edges of the base metal and the filler material are melted by the arc plasma and form a seam. An inert argon gas is fed to the welding bath through the burner nozzle automatically. It practically does not enter into chemical interaction with the molten metal and gases formed in the arc zone. Due to the fact that Ar is 38% heavier than air, it descends downward, displacing atmospheric gases from the weld zone, thereby protecting it and preventing the occurrence of defects in the welded joint. To reduce the porosity of the seam, 3-5% of oxygen can be added to the argon, then the metal protection is more active.

Argon arc welding provides the formation of a seam by means of large- drop or jet transfer of metal. Large-drop transfer results in a large spray and does not allow achieving a stable welding process. The technological characteristics of the weld obtained are worse than in semiautomatic welding in CO 2 . The jet transfer of metal provides argon welding at welding currents above I s = 260 A. The welding process becomes stable, the quality of the seam increases. But the application of such a high current strength often does not meet the technological requirements for the process (for example, it unnecessarily heats the workpiece and alters the properties of alloyed metals). Therefore, it is advisable to use switching power supplies. This allows us to proceed to the jet transfer of the metal already at currents close to I s = 100 A.

Ignition of the arc using a non-consumable electrode is carried out by a special device - an oscillator that is connected in parallel with the power source. When argon welding is performed on alternating current, after ignition of the arc, the oscillator switches to the stabilizer mode, giving pulses to the arc when the polarity changes. This ensures stability of arc burning.

If a direct current is used , uneven heat is generated at the cathode and anode (about 70% at the anode). Therefore, for steels, titanium alloys and other metals, except aluminum, the polarity is used straight to maximize the melting of the workpiece. Welding Al is performed on alternating current, which allows to destroy the oxide film without overheating the product.

Argon arc welding with a consumable electrode can also be used for welding parts made of stainless steels, aluminum and its alloys. But the field of its application is much narrower than with tungsten electrodes.

It finds application both manual and automatic argon welding. Its advantages include the ability to connect small products without filler materials, work with one-way access to the surfaces to be treated. The method is excellent for welding non-rotating joints of pipes from metal. The weld being formed has good technological parameters. Arc argon welding is the technology most suitable for joining alloy steels, titanium alloys, aluminum.

Due to the relative simplicity of the method, argon welding by one's own hands is available not only to professional welders. In this case, due to the small amount of work performed, the low productivity of the process is not so important, which limits its use in large-scale production.

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