Heat Input and Distortion Control Flashcards

Which welding technique deposits short weld segments in the opposite direction of the overall welding progression?

Answer: Backstep welding

Backstep welding deposits each short segment in a direction opposite to the overall joint progression, distributing heat more evenly and reducing shrinkage distortion.

Pre-setting (presetting) as a distortion control technique involves:

Answer: Positioning parts at an offset angle to compensate for expected distortion

Pre-setting positions the workpieces at an angle opposite to the expected distortion so that after welding and cooling, the parts return to the desired final position.

How does peening a weld bead between passes help control distortion?

Answer: It stretches the weld metal to counteract contraction stresses

Peening mechanically stretches the weld metal, opposing the contraction that drives distortion, though it should never be applied to the root or final cap pass.

Which distortion control method physically prevents movement by holding parts rigidly during welding?

Answer: Restraint and fixturing

Restraint and fixturing use clamps and jigs to hold parts in place during welding, physically resisting the shrinkage forces that would otherwise cause distortion.

Alternating weld passes on both sides of a joint to equalize shrinkage forces is known as:

Answer: Balanced welding

Balanced welding alternates passes symmetrically on both sides of the joint so that shrinkage forces cancel each other out, minimizing angular and longitudinal distortion.

Which type of distortion is caused by unequal transverse shrinkage through the thickness of a weld joint?

Answer: Angular distortion

Angular distortion occurs when transverse shrinkage is greater at the face of the weld than at the root (or vice versa), rotating the plates about the weld axis.

Compared to a few large passes, using more smaller passes in a multi-pass weld generally:

Answer: Reduces distortion by limiting peak temperature and heat input per pass

More, smaller passes keep heat input per pass low, reducing peak temperatures and thermal gradients, which results in less cumulative distortion than fewer high-heat passes.