Basuc Weld Faults And Their Causes

Question 1

All weld defects

Answer 1

Undercut 
Incomplete penetration 
Underfill 
Incomplete fusion 
Porosity 
Slag inclusion 
Cracking

Question 2

Types of cracking

Answer 2

Hot cracks, cold cracks

External cracks- crater, longitudinal and transverse

Internal cracks- underbead cracking

Question 3

Types of distortion

Answer 3

Longitudinal- shrinks along the length and bows inwards

Transverse- tendency for the plates in a butt joint to pull together down the length of the joint.

Methods to prevent: tacks along the length or put a wedge 12in to 18in ahead of the welding to hold the plates apart or prespacing.

Angular- the face shrinks and pulls the two pieces together
Method to fix: on a tee joint weld the other side of the joint.

Question 4

Distortion controls

Answer 4

• Avoid over welding
• Deposit the greatest amount of weld in the shortest amount of time (high rate of travel and use largest electrode possible)
• back-step welding sequence
• internment welding sequence
• Pre-bending or pre-spacing
• preheating and post-heating