What Shielding Gas Do I Need?
The type of shielding gas that should be used depends on the metal being welded. A mixture of 75% argon and 25% CO2 is the recommended shielding gas for collision repair on mild and high-strength steels. Pure argon is used for welding aluminum and when welding steel with silicon bronze wire.
A mixture of 75% argon and 25% CO2 is the preferred gas for collision repair welding because it improves both the yield and tensile strength of the weld and helps produce a smooth, stable arc with little spatter. This mix also produces a small weld puddle that sets up quickly, making it a good choice when welding out of position.
Although pure CO2 shielding gas can reduce the amperage required to make a weld, it's not recommended for collision repair welding. This is because it penetrates too deeply on thin-gauge metal and makes an unstable arc that increases spatter. Because it makes a hotter weld, and a larger heat-affected zone, it is not recommended for welding high-strength steels.
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