Powder thermal conductivity measurements in laser powder-bed fusion: an uncertainty study with sensitivity analysis

Laser flash testing and finite element (FE) heat transfer simulations have been together applied to measure the thermal conductivity of metallic powder contained in a solid specimen made by laser powder bed fusion (L-PBF) additive manufacturing. However, input parameters to the FE model potentially influence the accuracy of thermal conductivity evaluations. This study intends to investigate the effect of major uncertainties in the measurement of metallic powder thermal conductivity in L-PBF, including specimen dimensions, solid material properties, as well as the irradiation area and pyrometer detected area in laser flash testing, and to determine the sensitivity of various factors. A dummy-treated Taguchi method with different levels of the studied factors was utilized using the FE simulations and an inverse method. The results show that the dimension of the specimen's internal powder-enclosed cavity and the solid material properties have dominant effects on the evaluation of powder thermal conductivity. In addition, predictions from the regression equations are verified and give a reasonable agreement with the simulated powder thermal conductivity values.