Local Thermal Conductivity Mapping of Selective Laser Melted 316L Stainless Steel

The variation in thermal conductivity of 316L stainless steel samples produced with selective laser melting with a varying process parameters is investigated in the bulk and in the microscale. A critical scan rate was observed, while holding all other process parameters constant, above which the porosity started to rapidly increase. For the lowest-porosity sample, a local thermal conductivity map was produced using frequency-domain thermoreflectance. The local stainless steel thermal conductivity varied between 10.4 and 19.8 W/m-K. The average thermal conductivity of the thermal conductivity map agrees within measurement uncertainty with flash diffusivity measurements. The reduction in thermal conductivity with increasing scan rate is not fully explained by the porosity. The average measured values are less than conventionally produced bulk 316L due to the unique processing conditions of laser powder bed fusion, which modifies the crystallographic texture and microstructure.