Root notch
Root notch is a sharp-edged indentation at the weld root, caused by insufficient gap filling or uncontrolled penetration. It leads to premature cracking under fatigue loading and requires careful rework.
Physical-Chemical Effect Mechanism
The root notch forms due to insufficient gap filling or uncontrolled penetration, resulting in a sharp-edged depression. This edge can cause cracks under dynamic loading because it concentrates mechanical stresses and reduces the strength of the weld.
Metallurgical Relevance & Risks in Welding
The root notch increases susceptibility to cracking under dynamic loading. It can also lead to pitting or corrosion as it collects moisture and chemical compounds. The notch increases stress concentration points and can affect the weld microstructure.
Workshop Practice & Instructions
To avoid root notches, ensure proper gap filling and controlled penetration. For existing notches, careful rework is required. Use a fine grinder or polishing agent to smooth the edge. Make sure the weld is fully and evenly filled. Inspect the notch after rework with a microscope to ensure it's removed.