Achieving excellent fatigue crack growth resistance and tensile strength combination in multilayered TC4/TB8 structures

Here we report a multilayered TC4/TB8 titanium alloy structure fabricated by diffusion bonding that can produce an excellent property combination. Its fatigue crack growth (FCG) life increases by 6.2 times and 2.6 times compared to TB8 plate and TC4 plate, respectively. Meanwhile, the tensile ultimate strength reaches 1128 MPa, which is near high strength of TB8 alloy. The delamination at bonded interfaces and crack deflection within layers induced by different mechanical responses of both TC4 and TB8 alloys promote the FCG life improvement of multilayered TC4/TB8 structures. Besides, multilayered structures can obtain sufficient strength due to well-bonded joints and high-strength TB8 layers. The influence of dissimilar layers and interlayer cracking on the distribution of stress and strain fields at the crack tip was simulated using the Abaqus software.