Welding Discontinuities (7)

Question 1

Porosity

Answer 1

Entrapped gas in the weld.

• Dirt, rust, moisture
• Excessive arc length
• Improper weld technique
• Base metal or electrode composition

Question 2

Slag Inclusions

Answer 2

Slag that wasn’t quite removed.

• Embedded in weld
• Found in welds produced by Flux (SMAW, SAW, FCAW)

Question 3

Tungsten Inclusions

Answer 3

Pieces of tungsten electrode entrapped in the weld.

• Sharp edges
• Found in gas tungsten arc welds

Question 4

Incomplete Penetration (IP)

Answer 4

Inadequate penetration of the weld joint root by the weld metal

• Occurs at root of the weld
• Improper weld technique
• Improper joint geometry

Question 5

Lack of Fusion (LF)/Incomplete Fusion (IF)

Answer 5

Lack of union between weld metal and parent metal or inter-run or inter-pass lack of fusion.

• Parallel to direction of welding
• Can be associated to Slag Inclusions

Question 6

Undercut

Answer 6

Gouging out the base metal.

• Creates a stress riser
• Improper welding technique

Question 7

Cracks

Answer 7

• Hot Cracks
• Crater Cracks
• Cold or Under-Bead Cracks
• Lamellar Tearing

Question 8

Hot-Cracks

Answer 8

Cracks that occur at elevated temperatures.

• In the weld or Heat-Affected zone (HAZ)
• May occur in the end of a weld (Crater Crack)
• Shrinkage stresses during solidification

Question 9

Cold or Under-Bead Cracks

Answer 9

Cracks that occur immediately on cooling or after a period of hours or days.

• In weld or Heat-Affected Zone (HAZ)
• Presence of hydrogen
• Hard Martensitic microstructure in the HAZ

Question 10

Lamellar Tearing

Answer 10

Crack in the base metal of structural weld shapes.

• Internal
• Terrace-shaped
• May cause brittle fracture in structural steels
• High Non-Metallic Inclusions in parent metal
• Shrinkage during solidification