AWS Distortion Control & Residual Stress Flashcards

What is the primary cause of welding distortion?

Answer: Non-uniform heating and cooling creating unequal thermal expansion and contraction

Weld distortion occurs because the heated weld metal and HAZ expand and contract unevenly compared to the surrounding base metal.

Which technique involves bending a workpiece in the opposite direction before welding to compensate for expected angular distortion?

Answer: Presetting (preset)

Presetting means intentionally bending the parts in the opposite direction before welding so that distortion brings them back to the desired shape.

Which welding sequence technique reduces longitudinal shrinkage and distortion by dividing the weld into segments welded in the opposite direction to travel?

Answer: Back-step welding

Back-step welding divides the weld into short segments deposited in the direction opposite to overall progression, balancing shrinkage stresses.

What is 'angular distortion' in a butt-welded joint?

Answer: Rotation of the welded plates out of the original plane due to transverse shrinkage

Angular distortion is the rotation or tilting of the base metal plates out of their original plane, caused by unequal transverse shrinkage through the weld thickness.

Which distortion control method involves applying heat to the opposite side of a distorted weld to straighten the part?

Answer: Flame (heat) straightening

Flame straightening uses controlled application of heat to the convex side of a distorted part, which contracts on cooling and straightens the piece.

Which approach most effectively minimizes distortion in a symmetrical butt joint with a double-V groove?

Answer: Alternating weld passes on both sides of the joint (balanced welding)

Balanced welding — alternating passes on both sides of a double-V — keeps shrinkage forces symmetric, canceling angular distortion.