Types of Welding Rods
The Ultimate Guide
Being able to differentiate between the types of welding rods – and being aware of their strengths, weaknesses, and best uses – is just one of those features which have a huge impact on the strength and quality of your welds. In order to help you get to grips with this complex subject, we’ve put together the ultimate guide covering all welding rod types.
What is the welding rod?
The welding rod is the piece of wire connected to the welding machine. A current is fed through this wire, which helps to join two pieces of metal together firmly.
In certain cases – namely SMAW and stick welders – the wires actually melt, becoming part of the weld itself. These welding rods are referred to as consumable electrodes. For TIG welding, the welding rods do not melt, so are called non-consumable electrodes. Within both of these groups, there are many different variations and types, which will be covered in more detail later.
Welding rods are usually coated, although the materials that make up this coating can vary widely. Bare electrodes (those made without any additional coatings) are also available, although they’re much less common. These are used for certain specific jobs, such as welding manganese steel.
It is important to choose the right type of welding rod for your job in order to create clean, strong welds with excellent bead quality.
As mentioned previously, stick welders usually use consumable welding rods, which will be referred to as stick electrodes here. These include light coated electrodes, as well as shielded arc or heavy coated electrodes.
As the name suggests, light coated electrodes have been finished with a thin coating which has been applied by techniques such as brushing and spraying. This is usually made up of a combination of several different materials, which are likely to be similar to the metals which you are welding together.
The arc streams created when using bare rods can be difficult to control, so if your job allows it then using a light coated electrode increases the arc stability. This will make your life quicker and easier.
However, that is not the only purpose behind having a light coating on the welding rods. Other benefits of using light coated electrodes are that impurities such as oxides and sulfur are reduced (or eliminated altogether), the drops of metal at the end of the welding rods are more regular in both size and frequency – meaning that your welds are smoother and neater – and they only produce a thin slag.
Shielded arc electrodes are similar to light coated electrodes, except for the fact that they have a heavy coating. Due to their tougher, heavy duty nature, they are better suited to applications such as welding cast iron.
There are three different types of coating applied to shielded arc electrodes, which each have different results during the welding process. Firstly, there are those with coatings containing cellulose, which uses a layer of gas to protect the weld zone; the coatings on the second type include mineral substances, which leave a layer of slag. The third type of coating on shielded arc electrodes is made up of a combination of cellulose and minerals.
Shielded arc electrodes which form a layer of gas are ideal because they act as a highly effective protective barrier, resulting in strong welds. The weld pool needs to be protected from certain atmospheric gasses (namely oxygen and nitrogen), which affect the welds and make them weak, porous and brittle. This protection can either be given through the use of a coated welding rod, or through a blast of gas which can separate the weld pool from the air (as described in the cellulose-coated shielded arc electrodes).
Just like light coated electrodes, shielded arc electrodes reduce oxides, sulfur and other impurities in the metal, leaving clean, smooth, regular welds. In addition, the weld arcs created by these welding rods are much easier to control than bare electrodes, which are prone to causing lots of spatter.
It might seem like a hassle if you opt for a mineral-coated shielded arc electrode which forms a slag, but, in fact, this slag can have a beneficial effect. It cools slowly – much slower than cellulose-coated shielded arc electrodes – which draws impurities up to the surface. As a result, you’ll end up with high-quality welds which are strong, durable and clean.