A model of crystallization process taking into account phase changes in formation of a metallic material by laser fusion method

Theoretical principles of models of crystallizing bodies being developed are now applied to model the technological process of selective laser welding regarding the description of interaction between “melt - solid body” and determining a body’s buckling owing to emergence of residual stresses in a cooling down work piece. At the same time one of the relevant problems of the research is creating the defining relations which make it possible to describe the interaction between “melt - solid body”. This work considers the application of the known defining relations of the viscoelastic growing body for the hardening metal alloy. The crystallization process takes place in a wide temperature range and is followed by structural changes. A crystallization process is a transition of metal material from a liquid state into the hard one. Within the research, the general statement of the boundary problem of mechanics of the crystallizing body is considered. Realization of the defining relations describing the crystallization process is executed using two problems, i.e. the problem related to the nonuniform controllable cooling of the rod and plate’s cooling from the temperature that is higher than the melting point of the studied material. Thus, numerical models of crystallization of isotropic bodies taking into account phase transfers for linear and two-dimensional statements based on the finite element method have been obtained. The results of applying the finite element method based on the new defining relations do not contradict the physics of the crystallization process and can be applied, when modeling the selective laser welding of metal materials taking into account phase transfer. Images of stress-strain states of the structure have been obtained for each model problem: fields of distribution, stresses and strains. Also, the analysis of the numerical solution convergence is performed, the fulfillment of the natural boundary conditions is analyzed, the temperature fields and the degree of crystallization are obtained within the framework of the study.