Argon arc welding
In any industry in the modern steel era, the existence of welding technology is a must. MMAW (hand metal arc welding), SM AW (rod metal arc welding) and GTAW (gas tungsten arc welding) have been firmly established. This is because they are flexible, suitable for all positions and locations, and are easy to obtain the consumables required for various types of welding.
In most of our industries, welding is done using various types of rods or coated electrodes.
But today's industrialists are increasing their productivity to fight competition from domestic and international markets – especially as global industries become more competitive, and industrial management is constantly looking for new ways and means to reduce costs and improve QC.
In this case, users want to modernize their machines to run faster, longer, and more efficiently. They are looking for various advantages of automatic and semi-automatic welding processes - MIG / MAG, TIG, GTAW or gas shielded arc welding - this is the most modern welding technology machine tool. Argon arc or gas shielded arc welding is the most popular.
Now let us consider inert gases and their applications in welding science. As the name suggests, inert gases are inert gases. It is used to protect the weld pool from the atmosphere during welding. Important inert gases are helium and argon. They are used with other shielding gases.
Shielding gases can be divided into two groups:
(1) A gas soluble in or reacting with a metal. These are hydrogen, carbon dioxide, nitrogen, and the like.
(2) Inert gases such as helium and argon.
Argon and carbon dioxide are the most widely used. Argon is a by-product of the production of oxygen in air separation. Argon is supplied from a steel cylinder at a pressure of 150 atmospheres. The purified argon contains 97-98% argon, while the commercial argon contains 13-14% nitrogen.
It is convenient to consider the use of a gas involving the shielding of an electric arc with a mixture of argon, helium and carbon dioxide (CO 2 ) and argon with oxygen and CO 2, helium.
Argon is used as a shielding gas because it is chemically inert and does not form a compound. Commercial grade purity argon is about 99.996%, obtained by fractionating liquid air from the atmosphere. It is cheaper and therefore used for commercial purposes.
Argon gas in a commercial purity state is used for metal welding. Argon gas containing 5% hydrogen improves the welding speed and penetration of stainless steel and nickel alloy welds.
Tantalum can be used in aluminum and its alloys and copper. However, helium is more expensive than argon and, due to its lower density, requires a larger volume than argon to ensure shielding. Small changes in arc length result in greater variations in welding conditions.
A mixture of 30% helium and 70% argon provides a fast welding speed. Aluminum mechanized DC welding with helium has deep penetration and high speed.
Automatic argon arc welding has been successfully used to weld thin stainless steel, aluminum, and its alloys. Non-consumable or consumable electrodes can be used for the argon arc process. Using a non-consumable electrode, the arc is maintained between the tungsten electrode and the "working". An argon shield is projected around the electrodes.
The arc burns between the tungsten electrode in the shield of the inert gas argon and the workpiece, which eliminates the atmosphere and prevents contamination of the electrodes and molten metal. The hot tungsten arc ionizes the argon atoms within the shield to form a gas plasma consisting of an almost equal number of free electrons.
Unlike electrodes in a manual metal arc process, tungsten does not transfer to "work".
Figure 14.1 shows that the heat source during the inert gas protection welding process is the arc between the tungsten electrode and the parent metal. The electrode is shielded by an inert gas - argon or helium flow - which eliminates the need to add-flux.
AC is typically used with tungsten electrodes, which are used with consumable metal arc electrodes. This process is used to weld light alloys, some non-ferrous metals - especially aluminum, copper and its alloys, and stainless steel.
Using a consumable electrode, the arc is held between the metal electrode and the "workpiece." The steel is extensively welded by a semi-automatic C0 2 shielded arc process. In the aerospace industry, argon arc welding can be used on a large scale even with expensive welding. Argon should be dried by caustic or silica gel prior to use.
It has been successfully used to weld thin stainless steel, aluminum, and its alloys, copper and its alloys, nickel and its alloys, titanium, zirconium, silver, etc. The gas-shielded tungsten arc process allows these metals and various ferrous metals to be alloyed without the use of flux. This is a big advantage of all this welding.