Mathematical modeling of the process of selective laser melting of Ti-6Al-4V titanium alloy powder

Abstract

A digital (finite element) model has been developed for heating and melting of a layer of metal powder under conditions of its heating by a laser heat flux using a modern standard software product for assessing the geometric parameters of a molten bath brought about by the action of laser radiation on a layer of Ti-6Al-4V titanium alloy metal powder. The model takes into account latent heat released during the phase transition of the material; melting of the material in the temperature range of solidus and liquidus; radiation and convection from the surface of a layer of metal powder. It has been established that the formation of interlayer defects arising from inadequate penetration between layers or insufficient overlap between tracks is the main reason for the formation of porosity in materials synthesized by selective laser melting technology. So the depth of the molten bath should be at least 1.5 of the layer thickness for the synthesis of dense material. The results of numerical simulations made it possible to determine the range of technological scanning parameters upon application of which a melt pool with a depth of more than 75 m is formed.

Keywords

• additive technologies
• selective laser melting
• melt pool
• mathematical model
• double ellipsoid model of a heat source
• numerical simulation