Argon is the most commonly used gas. Helium is used for aluminum in some situations as the heat transfer thru it is better. A combination of the two is used in some shops. GTAW was first developed to weld aluminum during WWII and the process was called Heliarc (HELIum/electric ARC). Argon is cheaper to manufacture plus it being heavier than Helium it stayed down on the material being welded. Helium is a very light gas and floats away.
A C, with high frequency superimposed, when welding Aluminum. D C straight polarity on almost everything else.
High frequency stabilized alternating current power supply is the most used GTAW process for aluminum with pure tungsten electrodes.
CO2 is an oxygen compound or a non-inert gas,the purpose of a shielding gas is to shield the weld and the electrode from oxygen. argon, nitrogen and helium are the most common gases used for GTAW
For TIG - GTAW "heliarc" welding Argon replaced Helium because it is #1 cheaper #2 heavier so coverage is better (stays around the weld area).
Manual Metal Arc Welding(MMAW) Also GTAW (TIG) and GMAW (MIG) The MIG wire carries electric current so it is considered the electrode. TIG the Tungsten is considered an electrode.
It depends on what welding process is being used and what type of metal is being welded. When Oxy-Fuel Welding, Acetylene is the most popular. MAPP gas and Propane are also used. With the GMAW (MIG) process Argon, CO2 and Oxygen gasses, in mixtures or alone, are used. GTAW (TIG) gasses are almost always Argon and/or Helium. This is not all inclusive as new processes are being developed every day. Check with your welding material supplier for relevant info.
Yes .... but most welds will not be as good as those using flux. SMAW with bare electrodes produces poor results. GTAW and GMAW are done without flux when an inert gas is used to protect the puddle. Some Oxy-fuel welding can be done with out it. In most applications flux is used not only to protect the molten puddle but also add ingredients to the weld.
The only way to tig is to have your ground clamp hooked to the positive side of the welding machine. The negative lead will go to the tig torch. If it is reversed you will find out very quickly when you strike an arc. Most metals will be welded using this Polarity (straight). Most Aluminum TIG welding is performed using A C current.
It is most commonly used, due to the fact the materials that can be welded this way are very common, and the equipment is is relatively inexpensive.
To my knowledge there is no process called Argon Welding. Argon is an inert gas used to protect the weld puddle when using the GTAW (TIG/Heliarc) and GMAW (MIG) process. Almost all welding processes utilize electricity. OAW (Oxy-Acetylene now called Oxy-Fuel) being the exception.
Argon is the most common gas used in gas metal arc welding.