Determination of critical strain for rapid crack growth during tensile deformation in aluminide coated near-α titanium alloy using infrared thermography

Determination of strain for initiation of rapid crack growth is vital for designing coated components for aerospace applications. Knowledge of such strain is useful for prevention of catastrophic failure of coated components. In the present study this critical strain has been determined during tensile deformation of aluminide coated near-α titanium alloy using infrared thermography. A single step on-line method of determination of stored energy change as a function of true plastic strain, that incorporates conduction heat loss correction in a simple way, has been used to determine such strain level. It is shown that beyond a strain level the crack ensemble that form becomes unstable and further straining leads to rapid crack growth in the coating that penetrates into the substrate material. This manifests in an unprecedented trend in the stored energy change that has been identified with the strain for inception of rapid crack growth.