Creep degradation characterization of titanium alloy using nonlinear ultrasonic technique

• Creep degradation in titanium alloy Ti60 is characterized using nonlinear ultrasonic technique.
• Acoustic nonlinearity varied clearly with the change of creep loading time.
• Variation in acoustic nonlinearity is interpreted based on microstructure evolution.
• Precipitate–dislocation interaction is the dominant mechanism for acoustic nonlinearity change.

A through transmission nonlinear ultrasonic measurement has been proposed to characterize the creep degradation of titanium alloy that was conducted by creep tests at temperature of 600 °C. The experimental results show a change of “N”-like shape of the acoustic nonlinearity versus the creep loading time, which reveal based on metallographic studies that the variation of acoustic nonlinearity is closely related to the microstructure evolutions. An analytical model calculation has revealed a good agreement with the measured result, which indicates that the precipitate–dislocation interaction is likely the dominant mechanism responsible for the change of acoustic nonlinearity in the crept materials.