The superplastic forming/diffusion bonding and mechanical property of TA15 alloy for four‐layer hollow structure with squad grid

The superplastic forming/diffusion bonding (SPF/DB) process has been widely applied to manufacture the multi-layer components. In this paper, a four-layer hollow structure with squad grid was fabricated by SPF/DB process. The superplastic behavior of TA15 alloy was investigated by the uni-axial tensile tests at high temperature, and the maximum elongation of 911 % was obtained at 920 °C/0.001 s− 1. The finite element method (FEM) of the four-layer structure was conducted, and the results showed that TA15 alloy was appropriate for fabricating this complex-shaped structure. Then the four-layer hollow structure was successfully fabricated by SPF/DB process at 920 °C with the target strain rate of 0.001 s− 1. Finally, the microstructure, thickness distribution and mechanical property of the four-layer hollow structure were investigated. The grain size increased from 5 μm to 10 μm and the sound bonding interface was achieved. The thickness distribution was symmetrical in height direction. The compressive strength and the maximum bending load of the four-layer hollow structure was 50 MPa and 64.4 kN, respectively.