Computational Study of the Mechanical Behavior of Steel Produced by Selective Laser Melting

A two-dimensional numerical analysis of the evolution of grain structure observed during selective laser melting and of the mesomechanical behavior of additive manufactured specimens is performed. Cellular automata finite-difference model is developed to simulate the evolution of grain structure. A heat equation is solved with the use of the classical finite-difference scheme. The cellular automata model for the simulation of microstructural development is based on the approach put forward by Rappaz and Gandin. The Goldak double ellipsoid heat source model is adopted to describe the heat input during laser additive manufacturing process. An elastoplastic constitutive model including isotropic strain hardening is used to describe the mechanical response of additive manufactured specimens. A dynamic boundary-value problem in a plane strain formulation is solved numerically with the use of a Wilkins-type finite-difference scheme. The mesoscopic stress-strain state of additive manufactured specimens subjected to the uniaxial tension is analyzed. The focus is on the role of the inhomogeneous material microstructure in the evolution of the stress-strain state. A combined effect of grain structure and boundary conditions is investigated.