What is the purpose of peening while welding progresses?

Peening is a mechanical process that involves striking the weld with a tool or similar object as the welding progresses. The primary purpose of this application is to relieve internal stresses that can develop in the welded area due to the rapid heating and cooling cycles that occur during the welding process.

When metal is heated, it expands, and upon cooling, it contracts. This cycle can create residual stresses that may lead to warping, cracking, or failure of the weld over time. By peening, the surface of the weld is imparted with compressive stresses, which counteracts the tensile residual stresses that can lead to these complications. This technique is especially beneficial in preventing issues in critical applications where structural integrity is vital.

While enhancing aesthetics and increasing hardness could be secondary benefits in some specific situations, and cleaning the weld area is important for achieving good weld quality, the primary role of peening focused on stress relief is crucial in ensuring long-lasting and structurally sound welds.