Understanding Arc Welding Gas and How to Use It
Arc welding is a process that uses a welding power supply to create an electric arc between a metal workpiece and a consumable wire electrode. The arc melts the metal, allowing it to be joined together. This process is often done with the help of a shielding gas, which helps protect the weld from atmospheric contamination. In this article, we’ll look at the different types of arc welding gas, and how to use them for optimal results.
Arc Welding Gas and Its Uses
Arc welding gas is an inert gas that is used to create a shielding environment around the weld pool, protecting it from atmospheric contamination. Different types of gas are used in different welding processes, depending on the properties required. For example, Argon is commonly used for tungsten inert gas (TIG) welding, while carbon dioxide is often used for metal inert gas (MIG) welding.
The choice of gas is also determined by the type of metal being welded. For example, aluminum requires a special gas blend, as it is highly reactive to oxygen. Oxygen-free nitrogen can also be used to reduce oxidation in stainless steel and titanium.
When welding, it’s important to make sure that the gas flow is correct. If the gas flow is too low, the weld will be contaminated by the atmosphere, and if the flow is too high, the weld will be subject to excessive spatter. It’s also important to make sure that the gas is correctly aligned with the arc. If it’s not, it can cause turbulence, which can cause porosity in the weld.
Welding with GMAW Utilizes the Polarity
Gas metal arc welding (GMAW) is a common welding process that uses a consumable wire electrode and an inert gas to protect the weld pool from contamination. The process is often referred to as “MIG welding,” and it can be done with either a direct current (DC) or an alternating current (AC) power source. The polarity of the current determines the transfer of the metal from the electrode to the workpiece.
When welding with DC, the electrode is positively charged and the workpiece is negatively charged. This is known as reverse polarity, and it produces a spray transfer of the metal. When welding with AC, the electrode is negatively charged and the workpiece is positively charged. This is known as straight polarity, and it produces a globular transfer of the metal.
The choice of polarity is determined by the type of metal and the welding application. For example, thin metals tend to be welded using reverse polarity, while thick metals tend to be welded using straight polarity. It’s also important to make sure that the polarity is correct, as incorrect polarity can cause porosity, undercutting, and other welding defects.
Arc welding gas is an important part of the process, as it helps protect the weld from contamination. Different types of gas are used depending on the type of welding process and the type of metal being welded. It’s also important to make sure that the gas flow and polarity are correct, as these can affect the quality of the weld. By understanding the different types of gas and the parameters involved, you can ensure optimal results with your arc welding projects.