Superplastic forming/ diffusion bonding (SPF/DB) is a key technology for preparation of light-weight and integrated multi-layer structures as superplastic deformation and diffusion joints can be achieved in one heat cycle. However, groove defects and inhomogeneous sheets thickness distribution usually appear during SPF/DB, which decreases the mechanical properties of multi-layer structures. In this study, numerical models of four-layer honeycomb and hollow blade structure are established and the effects of forming parameters (thickness ratio, strain rate, DB distance and width) on groove defect and thickness distribution are analyzed. The results show that groove defect for honeycomb structure can be eliminated under proper thickness ratio between face sheet to core sheet. The groove defect decreases with increasing DB distance and decreasing DB width. Insufficient deformation of vertical stiffener is the main problem for hollow blade structure and it can be improved by adjustment of the sheets thickness and the strain rate. Experiments are conducted on the basis of optimized parameters from simulation and agree with results from FEM. This study provides guidance for parameters selection for manufacturing of Ti–6Al–4V multi-layer structure.

超塑性成形/扩散结合（SPF / DB）是制备轻质集成多层结构的关键技术，因为可以在一个热循环中实现超塑性变形和扩散接头。但是，在SPF / DB过程中通常会出现沟槽缺陷和不均匀的板材厚度分布，这会降低多层结构的机械性能。本研究建立了四层蜂窝结构和空心叶片结构的数值模型，并分析了成形参数（厚度比，应变率，DB距离和宽度）对沟槽缺陷和厚度分布的影响。结果表明，在面板与芯板之间的适当厚度比下，可以消除蜂窝结构的凹槽缺陷。凹槽缺陷随着DB距离的增加和DB宽度的减小而减小。垂直加强筋的变形不足是空心叶片结构的主要问题，可以通过调整板的厚度和应变率来改善。实验是基于模拟的优化参数进行的，并且与FEM的结果一致。这项研究为Ti-6Al-4V多层结构制造的参数选择提供了指导。