Use of SWIR Imaging to Monitor Layer-to-Layer Part Quality During SLM of 304L Stainless Steel
Abstract
This paper evaluates using in-situ SWIR imaging to monitor part quality and identify
potential defect locations introduced during Selective Laser Melting (SLM) of 304L stainless steel.
The microstructure (porosity, grain size, and phase field) and engineering properties (density,
modulus, and yield strength) depend on the thermal history during SLM manufacturing. Tensile
test specimens have been built with a Renishaw AM250 using varied processing conditions to
generate different thermal histories. SWIR imaging data is processed layer-to-layer to extract
features in the thermal history for each process condition. The features in the thermal history are
correlated with resulting part engineering properties, microstructure, and defects. The use of SWIR
imaging is then discussed as a potential for processes monitoring to ensure part quality and develop
layer-to-layer control in SLM.