Enhancement of glass welding strength by regulating the spatial distribution of residual stress

The welding performance of ultrafast laser glass welding is significantly influenced by welding strategies. Unlike continuous scanning welding strategy, discrete scanning welding strategy (DSW) can offer greater flexibility in modulating molten zones’ spatial arrangement. By DSW, the influence of molten zones’ spatial arrangement on welding performance and reliability was investigated, and its underlying mechanism was elucidated. Compared to the residual stress distribution characteristics in the upper and lower regions of a molten zone, an ordered residual stresses distribution was exhibited in the middle region of a molten zone. This can be attributed to a mild thermal treatment process in the middle region, and the region is suitable for placement at the welded glass interface. Furthermore, the effects of two representative patterns—orthogonal molten zone arrangement (OMA) and staggered molten zone arrangement (SMA) — on welding performance were investigated. Compared to OMA, SMA can mitigate the continuous residual stress concentration effect and enhance tensile strength. Comparative experiments demonstrate that the SMA can achieve reduced the average, maximum, and standard deviation of normalized residual stress by 33%, 53%, and 67%, respectively, and enhanced tensile strength by approximately 19%. The results prove that the optimizing molten zones’ spatial arrangement can effectively mitigate residual stress concentration and enhance the welding performance. This work provides valuable insights into residual stress regulation and offers guidance for the reliable fabrication of precision optical glass components.