Microstructure, distortion and residual stress investigation in a bio-inspired welding pattern

In Nature, when two surfaces are bonded, the joining interface usually follows a structurally optimized non-linear pattern, like cranial sutures. This distinctive characteristic of Nature could be imitated when joining thin plates by laser welding using a 'zigzag' path. It is expected that both welding stress and strain will develop in a different way as compared to the conventional butt-welding straight path due to a different heat flow and stiffness the weld bead undergoes during the welding process. To assess the resulting residual stress and distortion, as a function of the laser welding path, experimental investigations were carried out by X-ray diffraction technique and Coordinate Measurement Machine (CMM Hybrid), respectively. Results showed that the studied bio-inspired welding pattern can effectively alter both residual stresses and distortions. The outcome of this study unveils the potential of such a welding strategy to reduce the magnitude of detrimental tensile residual stress, opening new avenues to the development of more structurally efficient weldments as compared to standard linear welding.