2. Defects affect the quality of
weld
Porous welds
Poor penetration
Warping
Undercut & Underfill
Distortion
Cracked welds
Poor appearance
Poor fusion
Brittle welds
Spatter
Magnetic blow
Weld stress
3. Causes and cures of common welding
troubles
why?
1. Short arc, with the exception of low hydrogen and stainless.
2. Insufficient puddling time.
3. Impaired base metal.
4. Poor electrodes
What to do?
1. Check impurities in base metal.
2. Allow sufficient puddling time for gases to escape.
3. Use proper current.
4. Weave your weld to eliminate.
5. Use proper electrodes for job.
6. Hold longer arc.
Porous welds
4. Causes and cures of common welding
troubles
why?
1. Shrinkage of weld metal.
2. Faulty clamping of parts.
3. Faulty preparation.
4. Over heating at joint.
What to do?
1. Peen joint edges before welding.
2. Weld rapidly.
3. Avoid excessive space between parts.
4. Clamp parts properly; back up to cool.
5. Adopt a welding procedure.
6. Use high – speed, moderate penetration electrodes.
Warping
5. Causes and cures of common
welding troubles
Examples of various discontinuities in fusion welds
Fig. a) Underfill
Fig. a) Undercut
6. Causes and cures of common welding
troubles
why?
1. Uneven heat
2. Improper sequence.
3. Deposited metal shrinks.
What to do?
1. Tack or clamp parts properly.
2. Form parts before welding.
3. Dispose of rolling or forming strains before welding.
4. Distribute welding to prevent uneven heating.
5. Examine structure and develop a sequence.
Distortion
7. Causes and cures of common
welding troubles
Distortion of parts after welding
Fig. a) in butt joints
Fig. a) in fillet joints
8. Cracks caused by thermal
stresses
Types of cracks in welded joints caused by thermal stresses that develop
during solidification and contraction of the weld bead and the welded
structure .
Fig. a) Crater cracks
Fig. b) various types of
cracks in butt & T-joints
9. Causes and cures of common welding
troubles
why?
1. Faulty appearance
2. Over hang.
3. Improper use of electrodes.
4. Wrong arc and current voltage.
What to do?
1. Use a proper welding technique.
2. Avoid over heating.
3. Use a uniform weave.
4. Avoid over high current.
Poor appearance
10. Causes and cures of common welding
troubles
why?
1. Wrong speed.
2. Current improperly adjusted.
3. Faulty preparation.
4. Improper electrode size.
What to do?
1. Adjust electrode and ‘V’ size.
2. Weave must be sufficient to melt sides of joints.
3. Proper current will allow deposition and penetration.
4. Keep weld metal from curling away from plates.
Poor fusion
11. Causes and cures of common welding
troubles
Examples of various discontinuities
in fusion welds
Poor fusion
