Deformation mechanisms and prediction of laser butt-welded thin-walled laminated cooling plates with equivalent section-modulus modeling and experimental verification

Welding-induced out-of-plane deformation is a critical issue for thin-walled laminated cooling plates used in aero-engine hot-section components, where internal channels and supporting pillars markedly reduce bending resistance. This work investigates laser butt welding of GH3230 laminated plates through deformation and residual-stress measurements combined with directly coupled thermo-mechanical finite element simulations in MSC Marc. To model the complex internal architecture efficiently, the pin-fin pillars are simplified using a section-modulus-matching strategy that preserves the bending section modulus of the original cylindrical pillars. Two implementations are assessed. The square-pillar equivalence reduces computation time by more than 50% relative to the hexagonal scheme while maintaining comparable accuracy. Under identical heat input, laminated and solid plates exhibit similar longitudinal and transverse residual-stress distributions, whereas laminated plates develop much larger longitudinal warping and angular deformation. This contrast indicates that deformation is governed primarily by the spatial distribution and through-thickness gradient of welding-induced plastic strain rather than by the peak residual-stress level. A longitudinal four-bar model relates the longitudinal plastic-zone width to a stiffness-related parameter and through-thickness thermal asymmetry, and a transverse-section model shows that non-uniform transverse heating shifts the neutral plane and strengthens the through-thickness gradient of longitudinal plastic strain. Based on these mechanisms, heat-input-dependent amplification relationships are formulated to predict laminated-plate deformation from solid-plate FE results and validated on an additional plate-size pair, achieving a maximum relative error within 10% for both longitudinal warping and angular deformation.