What Are Welding Gases?

What Is Welding Gas?

Welding is defined as the process of joining metals to similar materials using heat and pressure. The general term for the gases used in this process is “welding gas.”

What Are Welding Gases?

Gases used to join metals can be used either alone or in mixtures. The following are the welding gases commonly used in industry and their properties:

1. Argon: A noble gas, argon has a higher density than air and is therefore preferred for horizontal welding. Welds made with argon have reduced penetration, and due to low arc voltage, it is ideal for thin workpieces.
2. Helium: It is the lightest of the welding gases and has high thermal conductivity. It is more commonly used for welding thick pieces. Because it is lighter than air, gas consumption is high, and it is typically used for overhead welding.
3. Carbon Dioxide: Supplied in pressurized cylinders, this gas is in liquid form and requires heat for vaporization. It is used as an auxiliary gas and as an inert shielding gas in welding processes.
4. Argon-Helium Mixture: A mixture of 75% helium and 25% argon provides better cutting capability in welding processes. Pure argon has the capacity for deep penetration.
5. Argon-Carbon Dioxide Mixture: When used alone, carbon dioxide can cause metal carryover. When mixed with argon, it ensures smoother welds and reduces spatter.
6. Helium-Argon-Carbon Dioxide/Oxygen Mixture: A mixture containing 90% helium, 7.5% argon, and 2.5% carbon dioxide shortens the arc length and creates an active atmosphere. A mixture containing 69% argon, 30% helium, and 1% oxygen, on the other hand, reduces spatter and improves the metal’s wetting properties.
7. Nitrogen: It is rarely used on its own, but it ensures safety during the welding of stainless steels.

Submerged Arc Welding and Submerged Arc Welding Gases

Gas-shielded welding is a type of welding performed with electrode wires under a shielding gas. In this process, the necessary heat is provided by the arc formed between the electrode and the metal. The gases used in gas-shielded welding are divided into two categories:

• Shielding Gases: These include gases such as argon, helium, and carbon dioxide.
• Active Gases: These are gases obtained from argon, helium, and mixtures of these gases.

Components Used in the Gas Shielded Arc Welding Process

• Power Source: A machine that generates the electrical power required for welding.
• Torch: A component that delivers the shielding gas and the welding metal to the weld pool.
• Wire Feeder: A mechanism that feeds the wire required for welding to the weld.
• Water Cooling Unit: Prevents overheating of the torch.
• Gas Cylinder and Pressure Regulator: Cylinders containing shielding gases.
• Chassis Cable and Welding Clamp: These complete the circuit to ensure the electrode functions properly.

Advantages of Submerged Arc Welding

The advantages of gas shielded welding over other welding methods are as follows:

• Prevents slag formation.
• Smaller-diameter electrodes can be used, which provides high metal deposition and current density.
• The low hydrogen content offers an advantage when welding steels that are prone to hardening.
• Better results are achieved when welding thin materials.
• It can be used efficiently in automatic and semi-automatic systems.