Covered electrode welding is a versatile and widely used process, but even the most skilled welder can encounter imperfections. Here are five common defects you might find on a weld, along with simple sketches to visualize them:
1. Slag Inclusion:
- Sketch: Imagine a dark, irregular line embedded within the weld bead.
- Description: Small pieces of molten slag (residue from the electrode coating) become trapped within the weld metal as it solidifies.
- Causes: Improper cleaning of the joint, incorrect welding angle, excessive current.
- Effects: Weakened weld strength, potential cracking, corrosion risk.
2. Undercut:
- Sketch: Picture a groove at the toe of the weld, where the base metal dips below the level of the weld bead.
- Description: Excessive melting of the base metal at the edge of the weld, creating a groove or undercut.
- Causes: High welding current, excessive travel speed, incorrect electrode angle.
- Effects: Reduced weld cross-sectional area, weakened joint, increased stress concentration.
3. Porosity:
- Sketch: Imagine small, round voids or gas pockets scattered throughout the weld bead.
- Description: Gas bubbles entrapped within the molten metal during solidification.
- Causes: Moisture on the base metal or electrode, improper shielding gas flow, contamination.
- Effects: Weakened weld strength, potential leakage paths, reduced fatigue life.
4. Incomplete Fusion:
- Sketch: Picture a gap or lack of bonding between the weld metal and the base metal.
- Description: The weld metal doesn’t fully penetrate and bond with the base metal, leaving unfilled areas.
- Causes: Low welding current, improper electrode manipulation, inadequate joint preparation.
- Effects: Weak joint, potential cracking, structural failure risk.
5. Spatter:
- Sketch: Imagine small, solidified droplets of metal scattered around the weld area.
- Description: Molten metal droplets ejected from the arc during welding, sticking to the surrounding surface.
- Causes: Incorrect electrode angle, excessive current, worn-out electrode.
- Effects: Aesthetically undesirable, potential surface damage, cleaning challenges.