Multiscale Simulations in Welds

Welding processes involve complex couplings between fluid dynamics, heat transfer and the metallurgical changes experienced by the base metal. Distortion, residual stresses, grain structure, cooling rates, high temperatures and consequently the reduced strength of a structure in and around a weld joint are produced by the localized thermal cycling caused by the intense heat input of fusion welding. With the virtual prediction of weld profiles (shape and size), solidification structures, distribution of impurities, formation of dislocations, distortions and residual stresses of a welded part, processes can be optimized in the early stages of prototyping.The technological properties of fusion welds are formed due to the simultaneous effects of different physical phenomena which occur on different length scales. Correspondingly the simulation of technological properties of fusion welds requires the multi scale approach.