What is the stress effect of a weld?

• A. Cooling welds create tensile forces around them, they may be localized tensile forces in compressive regions
• B. Welds relieve all residual stress
• C. Welds produce uniform compressive stress
• D. Welds only affect adjacent members

Answer: (A)

Welding introduces residual stresses because of the big temperature differences created as the weld cools and contracts. The weld metal heats up and expands, but as it cools it wants to shrink. The surrounding base metal and joints restrain that shrinkage, so tensile residual stresses develop in the weld region and in the heat-affected zone. These tensile stresses can be concentrated at the weld toes and along the weld, and you may also see localized tensile pockets in areas that are otherwise constrained. It’s not correct to say welding relieves all residual stress or that it creates uniform compressive stress, and welds don’t only affect adjacent members—the welded joint itself carries these residual tensions, which can influence fatigue performance and crack initiation.