Experimental investigation and thermographic imaging of geometry dependent overheating and its effects in PBF-LB/M

Abstract

This experimental study demonstrates a severe challenge in powder bed fusion of metals using a Laser beam (PBF
LB/M). Depending on the geometry of the manufactured part, heat can accumulate and cause significant overheating in
critical regions. The inhomogeneous temperature fields influence the thermal history and, thus, the resulting
microstructure and porosity. This influences thermal stress and the part properties. Additionally, shrinkage can occur in
the same regions for complex parts when multiple part areas merge during the PBF-LB/M process. Specimens with
suitable geometry were fabricated from AlSi10Mg and Alloy 718. The thermal behavior was observed using
thermographic measurements. The distortion of the specimens was measured and compared to their geometry and the
thermographic measurements. A potential approach was investigated where the thermal conditions were stabilized by
reducing the Laser power in critical regions. It was observed that the approach resulted in dense material with less
distortion, even if the corresponding Laser power led to compromised density in cold areas. Thus highlighting the
opportunity of parameter adaption during the build job.