Simulaciones Multiescala en Soldaduras

Abstract

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 multiscale approach.Keywords. Residual Stresses, Voronoi Cell Finite Element Modeling (VCFEM), Welding, Solidification; Dislocations. ResumenLos procesos de soldadura involucran acoplamientos complejos entre dinámica de fluídos, transferencia de calor y los cambios metalúrgicos que experimenta el metal base. Distorsión, tensiones residuales, estructura granular, tasas de enfriamiento, altas temperaturas y consecuentemente la resistencia reducida de una estructura en y alrededor de una junta soldada, son producidos por el ciclo térmico localizado causado por la intensa entrada de calor en soldadura de fusión. Con la predicción virtual de perfiles de suelda (forma y tamaño), estructuras de solidificación, distribución de impurezas, formación de dislocaciones, distorsiones y tensiones residuales de una parte soldada, los procesos pueden ser optimizados en la etapa temprana del diseño (prototipo). Las propiedades tecnológicas de las sueldas de fusión son formadas debido a los efectos simultáneos de diferentes fenómenos físi-cos los cuales ocurren a diferentes escalas. Correspondientemente, la simulación de las propiedades tecnológicas requiere la aproximación multiescala.Palabras Clave. Tensiones residuales, Modelación Voronoi-Elementos Finitos, Soldadura, Solidificación, Dislocaciones.Fusion welding processes are widely used for general repair applications. Successful repair requires the transient heat and fluid flow phenomena of the weld pool be addressed adequately to prevent the formation of new grains, equiaxed or columnar, ahead of the epitaxial columnar dendrites. It is well known that the dynamic behaviour of weld pools, due to heat and fluid flow in the weld pool, has significant influence on the temperature distribution, shape and size of the weld pool, final solidification microstructures, and consequently the resultant mechanical properties of the welded joints [1]. It is of great significance to understand the process quantitatively, focused on modelling the transient dynamics of the weld pool, especially the transient heating period after the arc ignites and the transient cooling period after the arc e...