Arc welding joins pieces of metal together using an electric arc that creates intense heat. The heat produced by the arc melts metals to form a weld pool that fuses the work pieces and hardens when it cools down. Types of arc welding include stick, TIG, MIG, and flux-cored welding.
Arc welding is a type of fusion welding that typically requires five components.
- welding machine
- welding gun
- ground cable
- Depending on the welding process, a shielding gas may be necessary to minimize contamination in the weld pool.
In this article, you will find all you need to know about arc welding. You will also learn about various welding processes used to create a strong, clean, robust weld join.
What is Arc Welding?
Arc welding is the process of using intense heat to melt two pieces of metal to form a metallurgical bond. For example, an AC or DC current and electrode create an electric arc, creating temperatures up to 6,500°F (3,593°C). This melts the electrode and the base metal to create a solid fusion.
What is the Arc Welding Process?
Various arc welding processes are involved in creating a robust, clean weld as strong as the base material.
The standard arc weld process uses a metal stick called an electrode, which can be consumable or non-consumable. An electrical current passes through the electrode, creating the arc. Then, the welder moves the electrode along the join to produce the weld.
The arc welding process also involves protecting the molten metal pool from contamination. The high temperatures created by welding cause metal to react with gasses in the air. Therefore, a shielding gas — usually a blend of 75% argon and 25% CO2 — is used to protect the weld pool from atmospheric contamination.
Another way to protect the weld joint in the welding process is to use the flux-cored arc welding technique. This is a type of electrode covered with flux. During the fusion welding process, this gives off vapors that act as a shielding gas and provides a layer of slag.
Why is Arc Welding Used?
Arc welding is the standard choice in welding for joining steel and other metals. Compared to gas welding, electrical arc welding is more cost-effective and can heat metal to a higher temperature. Additionally, arc welding equipment is highly portable and only requires an electrical power supply to work.
Arc welding is also better for working outdoors when it is wet and windy. For example, flux-cored MIG welding doesn’t require shielding gas, and there are no concerns about spatter. With modern arc welding technology, it is possible to weld thin metals and dirty metals.
What is Arc Welding Used for?
Arc welding is the standard process used in fabricating steel structures, making cars, and repairing metal objects. Arc welding became popular when used in shipbuilding in the early 20th century, and it’s now standard across the world. Additionally, arc welding is used instead of gas when the weld joint is thin, and great precision is required.
Arc welding is typically used for the following tasks:
- Welding thick metal plates
- Welding high-strength steel
- When it’s vital to ensure a high-strength weld free of serious defects
- Welding outdoors in all weather conditions
- Welding metal that is low-grade or dirty
Additionally, arc welding is used when high-quality welds are required. It is also the best choice for higher efficiency, portability, faster production, and fewer safety risks.
What is Shielded Metal Arc Welding (SMAW)?
Shielded metal arc welding is also called stick welding or manual metal arc welding. In the welding process, the arc is placed between the flux-coated electrode and the base metal. As the consumable electrode melts, a shielding gas forms to protect the metals from contamination. The electrode also becomes the filler metal in the weld joint.
With SMAW welding, there is no automatic feed for the electrode. Therefore, it must be replaced when it’s consumed. This is unlike flux-cored arc welding (FCAW), which continuously feeds a consumable flux-cored electrode
Best uses for shielded metal:
- Welding ferrous metals and alloys containing iron and carbon
What is Submerged Arc Welding (SAW)?
The submerged arc welding process uses a consumable wire or electrode that constantly feeds during the weld. The result is that the weld pool is immersed or submerged in a layer of powdered flux. This then absorbs any remaining spatter and prevents sparks. Generally, this welding process has a good electrical connection and fewer fumes.
Best uses for submerged arc welding:
- Welding low and medium-carbon steel, tempered steel, stainless steel, and low-alloy high-strength steel.
What is Electro-Slag Welding (ESW)
The electro-slag welding process is used to create vertical welds at least one inch thick. This type of weld works by the electric current passing between the work piece and the consumable electrode. The process produces a molten slag that covers the weld surface. The molten slag’s resistance to the electric current passing through generates the heat.
Best uses for electro-slag welding:
- Welding thick plates, such as ship, storage tank, and pressure vessel fabrication.
What is Gas Metal Arc Welding (GMAW)?
The gas metal arc welding process uses an electrical arc and a consumable metal inert gas (MIG) wire. GMAW welding works by the electrical arc forming between the MIG wire and the work piece. Shielding gas is pumped through the welding gun to protect the molten pool from contamination.
This is sometimes referred to as MIG welding or metal active gas welding (MAG). Because this type of welding uses an inert shielding gas, it is rarely used in outdoor settings. However, the advantages of GMAW welding is that it’s possible to use a faster welding speed, and there is no — or very little — slag left on the weld.
Best uses for gas metal arc welding:
- Welding most types of metals, but especially aluminum and non-ferrous metals.
What is Plasma Arc Welding (PAW)?
The plasma arc welding process uses a combination of a non-consumable electrode, plasma-forming gas, and shielding gas. This welding process works by the electric arc ionizing the gas, creating plasma. The plasma is then forced through a tiny hole. Because the plasma is electrically conductive, an arc forms between the metal work piece and the non-consumable tungsten electrode.
PAW welding uses a non-consumable electrode, meaning that no additional filler material is necessary to create a strong weld. This type of arc welding is used where precision and deep welds are required. Typically, plasma welding produces exceptional welds.
Best uses for plasma arc welding:
- Welding small metal components, steel tubes, and medical devices.
Arc welding is a popular form of welding because it’s the simplest. The advantages of arc welding are that it’s highly economical and quick and is suitable for most metals, including stainless steel and aluminum. Therefore, arc welding is used in all industries, including aerospace, automotive, construction, manufacturing, and oil and gas.
You will also find that arc welding is the choice of DIY enthusiasts in a home workshop or garage because it’s suitable for all kinds of projects.
However, arc welding requires a high level of skill to produce excellent results. But when the welder attains a good skill level, arc welding is one of the best ways to join metals together.