Argon arc welding is filled with argon during welding. What role does it play?

Argon arc welding is protected by filling argon gas during welding.

Based on the principle of ordinary arc welding, argon gas is used to protect the welding material, and the welding material is melted into a liquid state on the substrate to be welded by a large current to form a molten pool, so that the welding metal and the welding material are metallurgically combined. Because argon gas is continuously introduced during high-temperature melting welding, the welding material will not contact with oxygen in the air, which prevents the oxidation of the welding material, so stainless steel and iron metal can be welded.

Non-melting electrode argon arc welding is that the arc burns between the non-melting electrode (usually tungsten electrode) and the workpiece, and inert gas (usually argon gas) which does not react with the metal flows around the welding arc to form a protective gas cover.

Tungsten electrode, arc, molten pool and high temperature metal near the heat affected zone are not in contact with air, which can prevent oxidation and absorb harmful gases. So as to form a dense welded joint with excellent mechanical properties.

Extended data

Bottled argon gas for welding in China has a filling pressure of 15MPa at room temperature. The cylinder is painted with gray paint and marked with the words "argon". The chemical composition requirements of pure argon are: Ar ≥ 99.99%; he≤0.0 1%； O2≤0.00 15%； H2≤0.0005%； Total carbon content ≤ 0.001%; Moisture ≤30mg/m? .

Argon is an ideal protective gas, and its density is 25% higher than that of air. It is beneficial to protect welding arc and reduce the consumption of shielding gas during flat welding. Argon is a very inert gas, which will not react with metals even at high temperature, so there is no oxidation and burning loss of alloy elements and a series of problems caused by it.

Argon is also insoluble in liquid metal, so it will not cause pores. Argon is a monatomic gas, which exists in atomic state, and there is no molecular decomposition or atomic endothermic phenomenon at high temperature.

The specific heat capacity and thermal conductivity of argon are small, that is, the self-absorption is small, and the heat in the arc is not easy to be lost, which makes the welding arc burn stably and the heat is concentrated, which is beneficial to welding.

The disadvantage of argon is its high ionization potential. When the arc space is filled with argon, it is difficult to ignite the arc, but once it is ignited, it is very stable.

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