Commonly used arc welding process: TIG Welding & MIG Welding

TIG welding (Tungsten Inert Gas Welding), also known as non-melting extremely inert gas shielded arc welding. The inert gas is generally argon. Whether it is manual welding or automatic welding of stainless steel with a thickness of 0.5 to 4.0 mm, TIG welding is the most commonly used welding method. TIG welding with filler wire is often used for bottoming welding of pressure vessels, because the better air tightness of TIG welding can reduce the porosity of the weld seam during welding of pressure vessels. The heat source of TIG welding is DC arc, the working voltage is 10-95 volts, but the current can reach 600 amps.

TIG welding features:

1. Argon gas has an excellent protective effect, and neither chemically interacts with metals nor dissolves in metals. This makes the metallurgical reaction of the molten pool in the welding process simple and easy to control, and also provides good conditions for obtaining high-quality welds. For general active metals that are easily oxidized and nitrided, high melting point ferrous metals and dissimilar metals can be welded, and they are widely used.

2. Argon gas is only for protection and isolation during the welding process, so it has higher requirements on the surface condition of the weldment. The surface of the workpiece should be cleaned before welding. Remove the sludge, rust, dust and other impurities on the surface of the workpiece.

3. The arc burns very stably in argon gas, and still burns stably in the case of small current welding (<10A), and the filler wire is indirectly heated by the arc, so the heat input is easy to adjust. Therefore, this welding method is suitable for thin plate and all-position welding, and it is also an ideal method to realize single-sided welding and double-sided forming.

4. Since the filler wire does not pass current, there is no droplet transfer problem. There is no splash phenomenon during the welding process, and the welding seam is very beautiful.

MIG welding, an arc welding method that uses a melting electrode, adds gas as an arc medium and protects metal droplets, welding pools, and high-temperature metals in the welding zone, is called gas-shielded arc welding. The inert gas (Ar or He) shielded arc welding method with solid wire is called molten electrode inert gas shielded welding or MIG welding for short.

Different from TIG welding, MIG welding uses meltable welding wire as an electrode and uses the arc burning between the continuously fed welding wire and the workpiece to be welded as a heat source to melt the welding wire and wood metal. During the welding process, the welding wire is continuously melted and transferred into the welding pool in the form of droplets, fused with the molten base metal, and condensed to form the weld metal.

MIG welding features:

1. The inert gas hardly reacts with any metal, nor does it melt into the metal, so almost all metals can be welded. Especially suitable for welding aluminum and aluminum alloys, copper and copper alloys, stainless steel, and other materials. There is almost no oxidation burning loss during the welding process, only a small amount of evaporation loss, and the metallurgical process is relatively simple.

2. There is no coating layer on the surface of the welding wire, and the welding power source can be increased, so the penetration depth of the base metal is large, the welding wire melting speed is fast, and the deposition rate is high. Compared with TIG welding, its production efficiency is high.

3. Droplet transfer mainly adopts the form of jet transfer. The short-circuit transition is limited to thin plate welding, and the drop transition is rarely used in production. When welding aluminum, magnesium, and their alloys, the sub-jet transition is usually used because the cathode atomization area is large, the molten pool protection effect is good, and the welding seam is well formed and has few defects.

(picture from google)