What is welding slag?

Welding slag is a byproduct of the welding process that occurs when the weld metal melts and solidifies. Slag is a type of oxide that forms on the surface of the weld as it cools. It can range in color from grey to black and comes in different shapes and sizes, depending on the type of welding and the welding process used.

The formation of slag can be both beneficial and harmful to the weld. A small amount of slag is helpful in providing protection to the weld from the surrounding environment. It also helps to prevent the formation of porosity or holes in the weld.

On the other hand, excessive slag can impair the quality of the weld. It can create voids or inclusions that weaken the weld and reduce its overall strength. To avoid excessive slag, proper technique, and cleanliness are essential.

Slag removal is an important step in the welding process. It is removed by chipping, grinding, or using a wire brush. If slag is not completely removed, it can cause problems during subsequent welding operations, leading to uneven seams and weak welds. It is also essential to remove the slag before welding different materials, as it can contaminate the weld pool and weaken the joint.