Which combination is effective in reducing distortion during welding?

• A. Increase heat input; increase cooling rate; no clamps
• B. Limit heat input; limit cooling rate; clamp and prebend
• C. Add more filler metal; reduce speed; use larger electrode
• D. Use higher shielding gas flow; longer arc length; no preheat

Answer: (B)

Distortion in welding comes from uneven heating and cooling that creates residual stresses as the metal expands and then contracts. The most effective way to reduce it is to control both the heat introduced and how quickly the weld area cools, while also physically restraining and compensating the joint. Limiting heat input means the weld and heat-affected zone don’t experience excessive expansion. Controlling the cooling rate keeps temperature changes gradual, reducing differential contraction across pieces. Clamps hold the parts steady during welding so they don’t move out of alignment, and prebending compensates for the expected shrinkage so the final shape sits correctly after welding. Together, these actions address both the thermal and mechanical causes of distortion. Increasing heat input, speeding cooling, or neglecting restraint typically worsens distortion, and while preheating can help in some cases, this approach focuses on limiting heat, moderating cooling, and using restraint and prebending for best distortion control.