Welding rods are made from various metals including steel, cast iron, and aluminum and are coated with flux cellulose, titanium dioxide, and mineral silicates.
Welding rods are an important tool when you’re arc welding. They act as the electrode, which is the jumping-off point for your electric arc. Many types of welding rods differ by polarity, penetration, and many other properties. Many newcomers to welding struggle to understand not only the differences between types of welding rods but also what these tools actually are and what they are made of.
Welding rods are made of a metal filling and a flux coating. The actual materials determine the properties of the welding rod.
Here are the details you need to know about welding rods.
Table of Contents
What Are Welding Rods Made Of?
Welding rods consist of two important parts: the metal filling and the flux coating.
The metal filling is also called the true metal. For consumable electrodes, this is the part that melts into the welding joint. The melted metal becomes part of the joint, filling in the gap between the two pieces.
For non-consumable electrodes, the metal filling doesn’t melt into the filling. Usually, these electrodes are made of a tungsten core. Tungsten welding rods are most popular in TIG welding and other non-consumable techniques.
The other important component of the welding rod is the flux coating. Flux is a chemical material that prevents oxidation during welding.
Types of Materials in a Welding Rod
There are a few different materials that make up the metal in a welding rod. Here are some of the most common ones.
1. Steel
Steel is one of the most common components of a welding rod. There are actually a few different types of steel that can make up the core of a metal welding rod, including mild steel, high-tensile steel, and stainless steel.
Mild steel alloy welding rods usually come with a copper coating. Welders use them to weld steel as well as low-carbon and iron. These welding rods are some of the most common because they are affordable, work with different materials, and don’t rust even if you don’t use a flux coating.
High-tensile or high-carbon steel is another popular form of steel for metal welding rods. This type of welding rod is very common for repairs requiring more toughness, such as structural or construction. However, it oxidizes more easily than mild steel, so it has to have a flux coating.
Finally, stainless steel welding rods are used specifically for welding stainless steel.
2. Cast Iron
Besides steel, cast iron is a popular metal for making welding rods. You usually use iron welding rods to weld iron and other materials as these welding rods don’t work well with steel. Iron welding rods are tough and sturdy.
One type of welding rod combines the best of iron and steel. Nickel steel alloys are alloys of cast iron, steel, and other materials such as molybdenum or, of course, nickel. Although nickel steel alloys need flux as you weld, they are great because they are very strong and resistant to corrosion.
3. Aluminum and Other Materials
Although steel and iron are the most common metals for metal welding rods, they are not the only ones. Other metals, such as aluminum, bronze, and copper, are also used for welding rods.
However, these metals are much softer and have lower melting points than steel or carbon. You would only use these welding rods to weld base metals of the same material (for example, aluminum to weld aluminum and bronze to weld bronze). These base metals are too delicate for sturdy steel or iron welding rods, while the welding rods are too soft to weld tough steel or iron.
Unless you are working with these materials, you probably don’t need welding rods made of aluminum in your workshop and can stick with standard steel or iron.
Different Coating for Welding Rods
Besides the filler metal, the other important component of the welding rod is the flux coating. Most coatings use a cellulose base but can have many other materials in the composition. Here are some of the most common coatings for welding rods.
1. Cellulose
As mentioned above, cellulose is the most common ingredient for coatings. It works as a flux, which is a chemical that protects the weld. As you weld, the heat forces the cellulose to disintegrate and change from solid to gaseous. The gas then creates a shield, which protects the arc and the weld from oxidizing.
2. Titanium Dioxide
Many welding rods, including the popular 7014 welding rods, have a titania coating. Titania, or titanium dioxide, is a mineral oxide of the very tough element titanium. Titania has an important role to play in the welding rod. It helps ionize the arc and makes the slag freeze quickly while maintaining its fluidity. Titania-coated rods are perfect for welding quickly.
3. Mineral Silicates or Iron Powder
Sometimes, the coating of the electrode helps fill the weld pool. Mineral silicates or iron powder boost slag production because they melt off the electrode and join the weld. Then, you have more material to weld together, and it is easier to join two pieces. Which coatings is better for your job depends on the base material you are working with.
How Does Material Impact the Welding Results?
The material of the welding rod greatly impacts your welding results. A lot depends on your choice of base metal. You need to match the metal of the base metal to that of your electrode, especially if you are using a consumable electrode that will melt into your weld. Even if you are using a non-consumable electrode, different metal cores provide different weld strengths and amperages suited for different projects.
The flux coating is also important. As mentioned above, some elements of the flux coating, such as iron powder, melt into the slag, so you must also match your coating to the base metal. The coating also affects your weld’s speed, fluidity, and oxidation.
It takes experience to know which types of coating work best for which projects. Ask more experienced welders and carefully read manufacturer instructions when buying welding rods.
How to Read an Electrode Naming Code
It’s hard to keep track of the different properties of each welding rod. Luckily, the electrode naming code tells you all about the electrode.
You can learn about three important properties right in the naming code, including:
- Tensile strength
- Positioning
- Coating
The first two (or three) digits tell you about the tensile strength in tens of thousands of psi.
The second-to-last digit refers to the positioning. For example, “1” means the electrode works in all positions.
Finally, the last digit tells you about the coating. You don’t have to memorize which numbers stand for which coating because the producers of the welding rods will provide a table.
Final Thoughts
When choosing a welding electrode, make sure you choose one with the right base material and flux coating for your project. The electrode naming code can help you identify the important properties.
