To reduce heat distortion during welding, which approach is commonly used?

• A. Adjust material
• B. Use fume extraction
• C. Preheating and heat management
• D. Increase robot speed

Answer: (C)

Heat distortion in welding happens when the weld area heats up and cools unevenly, creating uneven shrinkage and residual stresses that warp the workpiece. The most effective way to reduce this is to manage heat input and cooling by preheating the material and controlling how heat is applied and removed during the weld. Preheating raises the base metal temperature, which lowers the temperature difference between the weld zone and the rest of the part. That slows the cooling rate, reduces residual stresses, and minimizes distortion. Good heat management also includes keeping interpass temperatures within limits, selecting appropriate welding parameters, and using fixturing or heat sinks to spread or remove heat more evenly.

Fume extraction addresses fumes, not distortion, and increasing robot speed can alter heat input but is not a reliable or standard distortion-control method. Adjusting material changes properties rather than actively managing the thermal cycle to prevent distortion.