What are some common welding defects and preventative measures for 3D welding tables?

1. Undercut
Phenomenon: The base metal at the edge of the weld melts but is not filled, forming a depression.
Cause: Excessive current, excessive arc length, improper welding angle.
Prevention: Adjust current and voltage, maintain the correct welding angle.
2. Cracks
Phenomenon: Fractures appear in the weld or heat-affected zone.
Cause: Excessive carbon, sulfur, and phosphorus in the weld pool, or excessive welding stress.
Prevention: Control material composition, use a reasonable welding sequence, and reduce stress.
3. Porosity
Phenomenon: Bubbles exist inside or on the surface of the weld.
Cause: Uncleaned oil and grease on the workpiece, damp welding rods, insufficient gas shielding.
Prevention: Clean the workpiece, dry the welding rods, and ensure stable gas flow.
4. Slag Inclusion
Phenomenon: Non-metallic impurities remain in the weld.
Cause: Excessive arc height, insufficient current, or incomplete inter-layer cleaning.
Prevention: Reduce arc height, increase current, and thoroughly clean the slag.
5. Lack of Penetration/Lack of Fusion
Phenomenon: The weld is not completely fused or the base metal is not sufficiently melted.
Cause: Insufficient current, excessive speed, or improper groove design.
Prevention: Adjust welding parameters, ensure reasonable groove angle and gap.