Name two factors that influence weld distortion.

• A. Electrode Coating Color.
• B. Gas Flow Rate And Shield Gas Type.
• C. Heat Input And Restraint During Welding.
• D. Welding Current Only.

Answer: (C)

Weld distortion happens because welding heats and cools the metal, causing expansion and contraction that, if parts are free to move or are restrained unevenly, leads to bending or misalignment. Two main factors controlling this are heat input and restraint during welding.

Heat input determines how much the weld and surrounding metal expand during heating and how much they contract as they cool. More heat input means larger heated zones and bigger temperature differences, driving greater plastic deformation and residual stresses that show up as distortion. Lowering heat input reduces these effects, helping keep tolerances, though it may impact weld quality if it becomes too low.

Restraint governs how freely the heated metal can move as it cools. When joints are tightly fixtured or restrained, shrinkage forces are distributed and blocked, reducing warping and bowing. Conversely, poor restraint allows more movement, increasing distortion.

In practice, controlling distortion is about managing heat input through welding parameters (current, voltage, travel speed) and improving restraint with proper fixturing, tack welding, and welding sequence. Other factors like electrode coating color or shield gas type don’t directly affect distortion in the same way.