Additive manufacturing of multi-material parts – A porosity analysis of 316L/CuCrZr using an automated characterization approach

The use of multi-material additive manufacturing (MMAM) to integrate dissimilar metals within a single build volume has been enabled by advances in powder bed fusion of metals using a laser beam (PBF-LB/M). While this opens up new functional possibilities, the process remains challenging with respect to defect control, particularly in bonding zones, where mismatched thermal properties promote the formation of pores and cracks that require precise characterization. This study investigates the influence of processing conditions, specifically the variation of laser power and scan speed, on porosity in 316L-CuCrZr specimens with lateral ( x - y ) material transitions. Porosity was measured using high-resolution optical microscopy and evaluated with ImageJ as well as a custom MATLAB-based image processing pipeline ( MultiPoroX ). This tool enables automated defect identification and localization across different material zones and part regions, and showed high agreement with the reference evaluations, with deviations of only 1–2%. Using the material combination of stainless steel 316L (1.4404) and copper CuCrZr (CW106C), key parameters such as porosity, defect area, and defect count were determined. The results reveal a clear dependence of porosity on the applied process parameters. A maximum porosity of 3.1% was observed, while the lowest porosity of 0.8% was achieved at 78 J/mm³ (316L) and 139 J/mm³ (CuCrZr). This work provides new insights into the optimization of PBF-LB/M parameters to reduce porosity and offers guidance for porosity analysis in multi-material parts.