Thermal conductivity of metal powders for powder bed additive manufacturing

•Thermal conductivities of metal powders for additive manufacturing were measured.•Infiltrating gas pressure and composition influence the powder thermal conductivity.•He infiltration yields 200% higher thermal conductivity than Ar or N2 at 1 atm.•Powder thermal conductivities depend weakly on temperature from 295 K to 470 K.•Gas-enhanced thermal conductivity is consistent with an effective medium model. The thermal conductivities of five metal powders for powder bed additive manufacturing (Inconel 718, 17-4 stainless steel, Inconel 625, Ti-6Al-4V, and 316L stainless steel) were measured using the transient hot wire method. These measurements were conducted with three infiltrating gases (argon, nitrogen, and helium) within a temperature range of 295–470 K and a gas pressure range of 1.4–101 kPa. The measurements of thermal conductivity indicate that the pressure and the composition of the gas have a significant influence on the effective thermal conductivity of the powder, but that the metal powder properties and temperature do not. Our measurements improve the accuracy upon which laser parameters can be optimized in order to improve thermal control of powder beds in selective laser melting processes, especially in overhanging and cellular geometries where heat dissipation by the powder is critical.