Diffusion bonding process for titanium alloy based on position limitation control

To meet the requirements of precision and high-performance diffusion bonding for titanium alloy structures, pure graphite was used as the position limitation block. Diffusion bonding tests of TA15 titanium alloy samples with different heights were conducted under the process parameters of a temperature of 920 °C, a pressure of 9.8 kN, and a holding time of 2 h. The effect of the position limitation gap (the height difference between the sample and the position limitation block) on the welding deformation, microstructure, and mechanical properties of the joints was analyzed. Results indicate that the position limitation gap has a significant effect on the deformation of diffusion-bonded joints of TA15 titanium alloy. As the position limitation gap increases from −0.05 mm to 0.2 mm, the welding deformation of the joints increases approximately linearly from 0.16 mm to 0.42 mm; the size and number of holes at the welding interface gradually decrease, and the tensile strength of the joints gradually increases to the level of the base metal. When the position limitation gap is 0.2 mm, the joint microstructure is basically completely bonded; discontinuously distributed β phases exist on the fusion line; the tensile strength reaches 962 MPa, and the tensile samples fracture at the base metal. Therefore, the diffusion bonding based on position limitation controlscheme can effectively control the deformation during the welding process of TA15 titanium alloys and exhibits strong regularity. Based on this deformation law, combined with the product structure compensation design, precision and high-performance welding of titanium alloy components can be achieved.