Welding Defects: Causes and Remedies Quiz

Welding Defects

• Welding defects are defined as weld surface irregularities, discontinuities, imperfections, or inconsistencies that occur in welded parts.
• Defects can result in rejection of parts and assemblies, costly repairs, reduction of performance, and catastrophic failures.

Distortion

• Distortion is the contraction of weld metal during welding that forces base metal to move.
• Possible causes: excessive heat input.
• Corrective actions:
  • Use restraint clamp to hold base metal in position.
  • Make tack weld along joint before starting weld operations.
  • Predict anticipated weld distortion and pre-camber base metal.
  • Select lower amperage for electrode.
  • Increase travel speed.
  • Weld in small segments and allow cooling between welds.

Incomplete Fusion

• Incomplete fusion is the failure of weld metal to fuse completely with base metal or a preceding weld bead.
• Possible causes: insufficient heat input, improper welding technique, and work piece dirty.
• Corrective actions:
  • Increase amperage and select larger electrode.
  • Place stringer bead in proper locations at joint during welding.
  • Adjust work angle or widen groove to access bottom during welding.
  • Momentarily hold arc on groove side walls when using weaving technique.
  • Keep arc on leading edge of weld puddle.
  • Remove all grease, oil, rust, paint, coating, slag, and dirt from work surface before welding.

Porosity

• Porosity is small cavities or holes resulting from gas pockets in weld metal.
• Possible causes: arc length too long, work piece dirty, and damp electrode.
• Corrective actions:
  • Reduce arc length.
  • Remove all grease, oil, rust, paint, coating, slag, and dirt from work surface before welding.
  • Use dry electrode.

Excessive Spatter

• Excessive spatter is the scattering of molten metal particles that cool to solid form near weld bead.
• Possible causes: amperage too high for electrode, arc length too long, and voltage too high.
• Corrective actions:
  • Decrease amperage or select larger electrode.
  • Reduce arc length or voltage.

Lack of Penetration

• Lack of penetration is shallow fusion between weld metal and base metal.
• Possible causes: improper joint penetration, material too thick, and improper weld technique.
• Corrective actions:
  • Improve joint penetration and design to provide access to bottom of groove.
  • Keep arc on leading edge of weld puddle.
  • Reduce travel speed.
  • Increase amperage and select larger electrode.

Burn-Through

• Burn-through is weld metal melting completely through base metal, resulting in holes where no metal remains.
• Possible causes: excessive heat input.
• Corrective actions: select lower amperage.

Mark/Locate Weld Defects

• Identify/determine location of weld defects in accordance with industry standard.
• Mark weld defects for repair in accordance with industry standard.
• Perform procedures in locating weld defects as per approved procedures.