Analysis of modern methods for reducing welding residual stresses

Abstract

This paper presents a systematic comparative analysis of the physical mechanisms governing internal stress generation in structural weldments, evaluates the efficiency of existing stress relaxation techniques, and provides scientific substantiation for promising dynamic approaches aimed at extending the operational life of welded structures.  It was established that conventional post-weld tempering of creep-resistant alloy steels under prolonged holding leads to the dissolution of strengthening nano-carbides and their boundary coagulation, resulting in a 4 – 5-fold reduction in long-term creep resistance. Surface plastic deformation methods, such as weld rolling and ultrasonic impact treatment, induce beneficial compressive stresses but remain restricted to a shallow depth of 1.5–2.0 mm or require extreme contact loads, whereas standard electromechanical vibration treatment with monochromatic excitation proves ineffective for thick-walled, high-rigidity structures with natural frequencies exceeding 200 Hz. Consequently, the transition toward dynamic pulse excitation is substantiated, as it generates shock deformation waves with steep-fronted rise times, excites higher-order spatial poly-harmonics, refines primary solidification dendrites by 25–32%, and relieves peak macro-stresses by 60 – 80%. The scientific novelty lies in determining the physical regularities of multi-mode dynamic stress relaxation within welded concentration zones through non-linear wave processes and intensified dislocation mobility without prolonged resonant structural overloading. The practical significance of the obtained results enables the justified selection of resource-saving stress relief technologies for heavy-duty and thick-walled fabrications, eliminating expensive furnace annealing while minimizing dimensional distortion