Effect of the top layer scanning on residual stresses and distortions in AlSi10Mg cantilevers fabricated by laser powder bed fusion

Laser Powder Bed Fusion (PBF-LB/M) enables lightweight and complex metal parts, but is prone to residual stresses and build-induced distortions that can compromise part quality. Cantilever specimens are widely used to study process control, support design, and post-processing, and they increasingly serve as calibration and validation references for simulations. However, an influential aspect has received little attention: the orientation of the top layer hatches relative to the cantilever beam axis. Here we show that, even when the established 67° rotational stripe strategy is maintained, the top layer scanning alone can change cantilever distortions by almost 50%, depending on the hatch orientation with respect to the beam. Using X-ray diffraction (XRD), we demonstrate that the near-surface principal stress system rotates with the top layer hatch orientation and that a higher support volume fraction increases the residual stresses in the surface layer. Distortion measurements after support removal reveal that long, slender beams are markedly more sensitive to changes in the top layer hatch orientation than compact beams, while the influence of support volume fraction on the final deflection is comparatively minor. A comparison with a chessboard strategy places it effectively near a 45° stripe orientation, i.e., between the extremes of hatches parallel (0°) and perpendicular (90°) to the beam axis. These findings clarify a key source of variability in cantilever-based studies. We recommend explicitly specifying and controlling the top layer scanning in experiments and simulations to ensure reproducibility, avoid misinterpretation, and to guide robust parameter selection for PBF-LB/M.