In TIG welds, which defect is expected in non-deoxidized steel?

• A. Undercut
• B. Porosity
• C. Tungsten inclusion
• D. Linear misalignment

Answer: (C)

In TIG (Tungsten Inert Gas) welding, non-deoxidized steel can be prone to tungsten inclusion. This defect arises when impurities or oxides present in the base metal are not effectively removed prior to welding. Non-deoxidized steel has a higher presence of these impurities, which can lead to tungsten from the electrode being inadvertently trapped in the weld.

Tungsten inclusion occurs because during the welding process, if the material is not clean, tungsten particles can become embedded within the molten weld pool. When the weld cools and solidifies, these tungsten particles remain, resulting in a defect that can compromise the structural integrity of the weld. It is important for welders to be diligent about cleaning the base material before welding to minimize the risk of tungsten inclusion and ensure a high-quality weld.

Other defects listed, such as undercut, porosity, and linear misalignment, are associated with different factors unrelated to the presence of non-deoxidized steel and mainly arise from issues like improper technique, contamination from moisture or other materials, or alignment problems. Focusing on preventing tungsten inclusion involves ensuring proper preparation and contamination control during the welding process.