What is Slag in Welding?
Slag is the brittle mass that forms over the weld bead on welds made with coated electrodes, flux cored electrodes, submerged arc welding, and other slag-producing welding processes. Welds made with the gas metal arc and the gas tungsten arc welding processes are slag free. Less oxidation generally makes slag more difficult to remove. Reducing speed usually helps.
Slag protects the weld bead from oxidation and contamination by atmospheric gases. It also provides a layer of insulation that prevents heat from being conducted to the base metal, which can help control warping and distortion.
Why slag is removed?
The type of slag used will depend on the welding process being used. For example, coated electrodes used in shielded metal arc welding produce a dense, fluid slag that is easily removed. Flux-cored electrodes used in flux-cored arc welding produce a more brittle slag that can be more difficult to remove.
How do you remove slag from welding? Why is it important to remove slag from the weld?
When welding with covered electrodes, the slag should be removed before it has a chance to cool and harden. This can be done by using a chipping hammer or wire brush. When welding with flux-cored electrodes, the slag should be removed when it is still hot and fluid.
What is slag inclusion in welding?
Slag inclusion is when slag particles become trapped inside the weld bead. This can happen if the welding process is not performed correctly, or if the slag is not removed properly. Slag inclusion can cause a variety of problems, including porosity, cracking, and reduced strength in the weld.
Submerged arc welding
Submerged arc welding (SAW) is a common welding process that uses an electrode that is submerged in a granular flux. The flux creates a barrier around the weld pool, which prevents oxidation and contamination. The flux also produces slag, which covers the weld bead and protects it from oxidation.