Continuous parametric scanning with thermal modeling to minimize stitch zone defects in laser beam powder bed fusion validated by multi-scale X-ray CT

Official URL: https://dx.doi.org/10.1016/j.addma.2026.105120

Stitch regions pose a fundamental challenge in both single and multi-laser systems due to overlapping scan areas where defects can form. This study introduces a continuous parametric scanning strategy designed to reduce porosity formation in stitch regions, which are frequently observed in these processes. The strategy was developed using a parametric modeling framework, which enables flexible and spatially adaptive scan-path generation while also producing the thermal-analysis inputs and build-machine files required for fabrication. By bridging the gap between design, simulation, and manufacturing, the framework supports a streamlined, end-to-end workflow tailored for metal additive manufacturing. The investigation was carried out in two phases, utilizing both transient thermal analysis and X-ray computed tomography (CT) to capture porosity across multiple scales. First, to assess the effectiveness of the proposed strategy, thermal simulations were conducted and the resulting cooling-rate distributions were analyzed. Second, these findings were validated through X-ray CT. Higher cooling-rate uniformity effectively reduced porosity formation in stitch regions. Each scanning strategy resulted in distinct mechanisms of pore formation that varied in pore size, shape, spatial distribution, and location. Compared with traditional strategies, the proposed continuous approach increased the thermal uniformity, reduced the average pore size by 25%, increased pore sphericity, and decreased the standard deviation of pore sizes.