Numerical modelling of pulsed and continuous wave direct laser deposition of Ti-6Al-4V and Inconel 718

Abstract

Effect of varying laser pulse parameters in laser direct metal deposition (LDMD) of Inconel 718 and Ti-6Al-4V have been shown to be quite complex and results in generation of two brittle phases Ti2Ni and TiNi3. Previous experimental study carried out by the authors discussed by Shah et al. (Sci World J 2014:6, 2014) the LDMD of Inconel 718 and Ti-6Al-4V, where all the sample developed cracks except with ones at low powder feed rate. In order to understand the effect of thermal and structural history on development of stresses during LDMD process, an extensive numerical modelling study has been carried out in the work. Thermal and structural analysis results are verified using the available experimental data. Residual stresses are calculated using numerical modelling in the clad region and at the interface of clad and substrate. Experimental and modelling results show that powder mass flow rate plays an important role in crack development during deposition of Inconel 718 and Ti-6Al-4V and it should be kept at minimum level in order to deposit crack-free samples.