Study of various parameters on residual stress relaxation for different welded components

Welded structures often experience different loading conditions before entering service or during service, which can result in redistribution/relaxation of the initial welding residual stress (WRS). This work seeks to study the effects of various parameters on residual stress (RS) relaxation for different welded components. A series of numerical calculations are performed by the finite element method to comprehend the mechanics of RS relaxation. Welding calculations are first carried out to predict WRS starting with a welded component with simple geometry to a more geometry-complicated welded component. Elastic-plastic shakedown calculations are thereafter performed considering various parameters including welded component geometry, number of load cycles, state of the initial WRS, and nominal stress range. The effects of the weld length and specimen size on the state of the initial WRS and the degree of RS relaxation after shakedown are also investigated. The shakedown calculations reveal that the geometry of the welded component is a key parameter that significantly contributes to the degree of RS relaxation whether WRS is ignored or considered, particularly at high-loading conditions. The magnitude and depth of the local equivalent plastic strain are also discussed where they increase by increasing the complexity of the welded component. This results in generating a local compressive stress field at the weld toe in the absence of WRS at high-loading conditions. It is also noticed that the longer the weld bead or the larger the plate width the larger the generated mechanical restraint, which will result in increasing the degree of RS relaxation.