Estimation of Effective Thermal Conductivity of Ti-6Al-4V Powders for a Powder Bed Fusion Process Using Finite Element Analysis

Abstract

A powder bed fusion (PBF) process, involving heating, sintering, melting, and solidification of powders, is one of representative metal additive manufacturing processes. In numerical analyses of the PBF process, appropriate temperature dependent material properties of powders considering the change of contact area between powder particles induced by local melting in the vicinity of the contact region are needed to obtain accurate analysis results. The goal of the paper is to investigate a novel method to estimate an effective thermal conductivity of Ti-6Al-4V powders considering the change of the contact area between powder particles during sintering of powders in a PBF process using a unit cell model with the sintered neck and the finite element analysis. The effects of the neck ratio and the temperature on heat transfer characteristics in the unit cell and the thermal conductivity of the powder are examined. The effective temperature dependent thermal conductivity of Ti-6Al-4V powders is estimated by a linear interpolation method and a thermal conductivity-temperature curve. Through the comparison of the estimated effective thermal conductivity of powders and the results of previous studies, it has been shown that the proposed method appropriately estimates the effective thermal conductivity of the powder during heating and sintering of the powders.