Question

Which of the following is true regarding undercutting defect?

(a) Undercutting is due to local increase of thickness of parent metal at weld toe

(b) It is due to insufficient current

(c) It can be corrected by depositing additional weld material

(d) It is not easy to detect

The question was posed to me in an interview for job.

This intriguing question originated from Weld Defects & Types of Joints in division Welded Connections of Design of Steel Structures

Answer 1

The correct option is (c) It can be corrected by depositing additional weld material

For explanation I would say: Undercutting is due to local decrease of thickness of parent metal at weld toe. This results in groove in base metal adjacent to toe of weld and left unfilled by weld metal during welding process. Undercutting may result in loss of gross section and will act as stress riser. This defect may be due to excessive current or longer arc length. It can be easily detected visually and can be corrected by depositing additional weld material.