A 3D model of heat transfer in inhomogeneous materials taking into account phase transitions for analysis of laser welding of dissimilar metals using intermediate insert is developed. Based on the proposed model, an algorithm is constructed and numerical studies are carried out of the distribution of temperature fields in the weld joint of titanium and stainless steel with an intermediate copper insert. The processes of melting, evaporation, and solidification of the materials depending on the beam power, its speed, and position of the focal spot in the system are studied. The welding modes reducing interaction of elements of the materials welded and, thus, preventing formation of brittle intermetallic phases in the weld joint are found. (C) 2016 Elsevier Ltd. All rights reserved.