Optimization and Characterization of Metallic Multi-Materials by Laser Powder Bed Fusion

Abstract

Additive manufacturing, or 3D printing, has largely developed in the last 5-10 years and a lot of companies were created by coming up with ingenious and new processes, Aerosint is one of them. Aerosint has developed the first Laser Powder Bed Fusion printing head that allows to print two materials at the same time. In this work, some thermal properties of pure and bi-material parts are studied. The pure metallic parts are made out of CuCrZr and Maraging steel M300 and the bi-metallic parts are made out of a both. The evolution of the thermal diffusivity is studied for the as built printed parts and for two aging treatments, one at 520°C during 45 min and one at 520°C during 6h. Then the augmentation in diffusivity induced by the addition of copper on the steel is studied. After that a measurement of the evolution of the contact resistance between the two metals is led. Finally, a short study of the evolution of the grain size in the copper alloy is done thanks to the ASTM E112 standard. The results show that for the CuCrZr the diffusivity is 3 times higher after 45 min of aging and stays stable after (from 30 to around 90 mm^2/s). For the M300 the diffusivity is multiplied by 1.1 for a heat treatment of 45 min and by 1.3 for a heat treatment of 6 hours (from 4.5 to 5.5 mm^2/s to 6.5 mm^2/s), so for the steel alloy the aging does not do much, at least in terms of diffusivity. The bi-material part has around 1.8 times better diffusivity than the steel alone for the as-built part and for the heat treated parts it is around 2.3 times better. The contact resistance drops down to around 10% of its as built value after 45 min of heat treatment and then goes up again to around 15 of its as built value after 6h of heat treatment (from 1.5 x 10^(−5) to 1.7 x 10^(−6) m^2K/W). The use of ASTM E112 says that the grain size does not change during the heat treatments and stays at around 6.