Superplastic Tension Behavior of Dissimilar TC4/SP700 Laminate through Diffusion Bonding

Superplastic forming is a practical method to manufacture complex-shaped parts of titanium alloys with large deformation. Laminated parts of dissimilar titanium alloys fabricated by superplastic forming can achieve excellent performance by combining the advantages of components. This work displays the superplastic tension behavior and microstructural evolution of dissimilar TC4/SP700 laminate prepared by the diffusion bonding process. Two titanium alloys can achieve metallurgical bonding at parameters of 800 ℃/1 h/5 MPa. Except for dynamic recrystallization and grain growth behaviors upon superplastic tension, stress-induced phase transformation plays an important role in α to β phase transformation apart from the elevated temperature. The superplastic deformation can be attributed to the grain boundary sliding accommodated multiplex motion of dislocations. In addition, the retained strengths of all dissimilar TC4/SP700 laminates after superplastic deformation with different strain rates and temperatures range from 807 to 890 MPa.