TIG welding (Tungsten Inert Gas welding) is a welding method that uses pure Ar as a shielding gas and tungsten electrode. TIG welding wire is supplied in straight bars of a certain length (usually 1m).
An inactive gas protects the arc between the tungsten electrode and the workpiece to melt the metal and form the weld. The tungsten electrode does not melt during the welding process; it only acts as an electrode. At the same time, the welding torch sprays in argon or helium gas for protection. Additional metal can also be added as needed. This is commonly known as TIG welding internationally.
The main advantage of TIG welding is that it can weld a wide range of materials, including workpieces with a thickness of 0.6mm or more, and materials including alloy steel, aluminum, magnesium, copper and its alloys, gray cast iron, ordinary dry, various bronzes, nickel, silver, titanium, and lead. The main application field is welding thin and medium-thick workpieces and used as a welding root pass on thicker sections.
MIG welding, or inert gas metal-arc welding, is a welding method that uses inert gases such as Ar as the main protection gas. This includes pure Ar or a small amount of active gas (such as less than 2% O2 or less than 5% CO2 gas) to perform metal-active gas arc welding. MIG welding wire is supplied in coils or spools in a layer-wound manner.
This welding method uses the arc burned between the continuously-fed welding wire and the workpiece as the heat source, with gas sprayed out of the welding torch protecting the arc for welding.
The protection gases commonly used in metal-active gas arc welding include argon, helium, carbon dioxide gas, or a mixture of these gases. When using argon or helium as the shielding gas, it is called inert gas metal-arc welding (commonly known as MIG welding) internationally. When using a mixture of inactive gas and oxidizing gas (oxygen, carbon dioxide) as a protective gas, or when using carbon dioxide gas or a mixture of carbon dioxide and oxygen gas as a protective gas, it is collectively known as metal-active gas welding (commonly known as MAG welding) internationally.
The main advantage of metal-active gas arc welding is that it can easily perform welding in various positions while also having the advantage of faster welding speed and higher deposition rate. Metal-active gas arc welding is suitable for welding most major metals, including carbon steel, alloy steel. Inert gas metal-arc welding is suitable for stainless steel, aluminum, magnesium, copper, titanium, zirconium, and nickel alloys. Electric arc spot welding can also be performed using this welding method.
The flow rate of the protective gas should be around 20-25L/min;
The arc length should generally be controlled at about 4-6mm;
The impact of wind on welding is particularly detrimental. When the wind speed exceeds 0.5m/s, wind protection measures should be taken; be aware of ventilation and preventing harm to the operator;
Using a pulsed arc current can obtain a stable jet arc, which is especially suitable for welding stainless steel, thin plates, and vertical welding and overlay welding;
For ultra-low carbon stainless steel, please use the Ar+2% O2 gas combination for welding, and avoid the use of Ar and CO2 gas mixtures for welding steel;
Impurities such as oil, rust, and water at the weld joint should be strictly removed during welding.
The flow rate of the protective gas should be around 7-12L/min when the welding current is between 100-200A and 12-15L/min when the welding current is between 200-300A. The performance of the welding joint could be affected because the protective gas could become mixed with humid air due to damage to the delivery pipe;
The tungsten electrode should be extended as short as possible relative to the nozzle, and the arc length should generally be controlled at 1-4mm (2-4mm when welding carbon steel, and 1-3mm when welding low-alloy steel and stainless steel);
When the wind speed exceeds 1.0m/s, wind protection measures should be taken; be aware of ventilation and preventing harm to the operator;
For welding, impurities such as oil, rust, and water should be strictly removed from the weld joint;
It is recommended to use a direct current power source with a steep descent outer characteristic, with the tungsten electrode as the positive pole;
When welding low-alloy steel with a chromium content of more than 1.25%, the back side should also be protected.