One objective of mechanical design of welded fabrications is to compensate loads by stresses which the materials used in structural components can accommodate.Beside these load-induced stresses, residual stresses also have to be considered.These residual stresses are built up during weld pool cooling.All welded structures therefore have residual stresses, which can be relieved by heat treatment to below the yield-stress level at the annealing temperature.If not fully relieved, their presence can accelerate corrosion and corrosive cracking of welds.