To indicate the TIG welding can be used the following names
RAD - manual argon-arc welding of non-consumable electrode, AMA - Automatic argon-arc welding of non-consumable electrode, AADP - automatic argon-arc welding with consumable electrode.
To indicate the argon-arc welding TIG: TIG - Tungsten Inert Gas (Welding) - welding with tungsten inert gas GTAW - Gas Tungsten Arc Welding - gas tungsten arc welding
General characteristics of argon-arc welding
Argon almost did not enter into chemical interaction with the molten metal and other gases in the combustion zone of the arc. Being a 38% heavier than air, argon displaces it from the weld zone and reliably isolate the weld pool from the contact with the atmosphere.
In argon-arc welding is possible krupnokapelny or inkjet transfer of electrode metal. When krupnokapelnom transfer welding process is poor, with a great splash. Its technological characteristics worse than semi-automatic welding in carbon dioxide, as due to lower pressure in the arc drops grow to large sizes. The range of currents for krupnokapelnogo transfer is large enough, such as wire diameter d = 1,6 mm I St = 120-240A. With a current of I St. 260A is more abrupt transition to the jet transport, the stability of the welding process is improved, reduced spatter. However, these currents do not always correspond to the technological requirements. Therefore, a more efficient process for stability using pulsed arc power sources that provide a transition to spray transfer at currents near I St. ≈ 100A.
Technology of argon-arc welding with non-consumable electrode
Arc between a workpiece and the consumable electrode (usually of tungsten). The electrode is located in the burner, which is blown through a nozzle shielding gas. Filler material is fed into the zone of the arc from the side and in the electrical circuit is not included.
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| Non-consumable electrode argon-arc welding, the process |
In this method of welding arc ignition, unlike welding consumable electrode can not be accomplished by touching the electrode products for two reasons. First, argon has a sufficiently high ionization potential, and therefore ionize the arc gap by sparks between the product and the electrode is quite difficult (for argon welding consumable electrode after the wire touches the product, in the arc zone appear a pair of iron that have ionization potentials in 2.5 times lower than that of argon, which allows you to ignite the arc). Second, the tungsten electrode touching the product leads to its pollution and intense melting. Therefore, for argon welding consumable electrode for ignition of the arc power supply is connected parallel to the device, which is called the "oscillator".
The oscillator for the ignition of the arc to the electrode delivers high-high-voltage pulses that ionize the arc gap and provide the ignition of the arc after the welding current. If the argon welding done with alternating current, the oscillator after the ignition of the arc enters the regulator and sends impulses to the arc at the time of polarity reversal to prevent a deionizing the arc gap and sustain the arc.
When welding with direct current at the anode and the cathode is allocated different amounts of heat. At currents up to 300A 70% of the heat released at the anode and the cathode 30%, so almost always used direct polarity to maximize the minimum product proplavlyat warm electrode. All steel, titanium and other materials, except aluminum, welded to the straight polarity. Aluminum is typically welded using alternating current to improve the fracture of the oxide film.
To improve the fight against porosity is sometimes added to argon oxygen in an amount of 3-5%. At the same time protecting the metal becomes more active. Pure argon does not protect the metal from dirt, moisture and other impurities caught in the welding zone of the welded edges or filler metal. Oxygen is by entering into chemical reactions with harmful impurities, burn, or provides them with the transformation of the compounds, pop to the surface of the weld pool. This prevents porosity.
Scope and benefits of TIG welding
The main area of non-consumable electrode argon-arc welding - compounds of the alloy steels and nonferrous metals. For small thicknesses, argon welding can be performed without additives. The method provides a good quality of welding and the formation of welds accurately maintain the depth of penetration of metal that is very important when welding thin metal at the one-way access to the product surface. It is widespread in the welding equipment, which has developed various designs of welding machines. This form is sometimes called orbital welding. Non-consumable electrode welding - one of the main ways of joining titanium and aluminum alloys.
Argon welding consumable electrode used for welding stainless steels and aluminum. However, the extent of its application is relatively small.
Disadvantages of TIG welding
The disadvantages of TIG welding is a low performance when using the manual option. The use of automatic welding is not always possible for the short and variously seams.
See also:
Argon and its application for welding
Argon welding of aluminum and other welding methods
Argon welding of titanium and other welding methods
Welding technology:
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