An Investigation into Metallic Powder Thermal Conductivity in Laser Powder Bed Fusion Additive Manufacturing
Shanshan Zhang, Brandon M. Lane, Justin G. Whiting, Kevin Chou
This study investigates the thermal conductivity of metallic powder in laser powder-bed fusion(LPBF) additive manufacturing. The intent is to utilize a methodology combining laser flash testing, finite element (FE) heat transfer modeling and an inverse method to indirectly measure the thermal conductivity of nickel-based super alloy 625 (In625) and Ti-6Al-4V powder in LPBF. The testing specimen geometry was designed with powder enclosed after LPBF fabrications to mimic the powder bed state. The specimens were then tested in a laser flash system to measure a transient temperature response of the samples. Next, a developed FE model and a multi-point optimization algorithm were applied to inversely analyze the thermal transient, and extract the thermal diffusivity and conductivity of LPBF powder. The results indicate that the thermal conductivity of In625 powder in LPBF ranges from 0.65 W/(m∙K) to 1.02 W/(m∙K) at 100 °C and 500 °C, respectively. On the other hand, Ti-6Al-4V powder has a lower thermal conductivity than In625 powder, about 35 % to 40 % smaller. However, the thermal conductivity ratio of the powder to the respective solid counterpart is not much different between the two materials, about 4 % to 7 %, which is largely temperature independent.
Proceedings of the Solid Freeform Fabrication Symposium