Characterisation of the fatigue process of U71Mn steel based on non-linear ultrasonic technology

作者：Wan, Chuhao; Gang, Tie^*; Liu, Bin; Wang, Changxi

来源：Insight: Non-Destructive Testing and Condition Monitoring , 2015, 57(7): 389-394.

DOI：10.1784/insi.2015.57.7.389

• non-linear ultrasonic technology
• beta-N curve
• characterisation of fatigue
• U71Mn steel

Non-linear ultrasonic technology is used for the characterisation of microstructures in U71Mn steel under fatigue loading, where the fatigue number, N, ranges from 0 to 150 x 10(3) cycles. In this experiment, weak second-harmonic signals are extracted to determine the non-linear ultrasonic coefficient, beta. The beta-N curve, which describes the relationship between the non-linearity coefficient and the fatigue number, is proposed here as an effective indicator of fatigue damage. Transmission electron microscopy, scanning electron microscopy and metalloscopy are used to understand the microstructural changes that occur during the fatigue process and to study the correlation between the microstructure and the non-linear ultrasonic coefficient. The dislocation density, closed cracks and macroscopic cracks are found to be the major reasons for the change in the non-linear coefficient. Conventional C-scan ultrasonic technology is used as a control experiment in this paper. The study demonstrates that non-linear ultrasonic technology can be used for the non-destructive characterisation of the fatigue process of U71Mn steel.

• 单位
  哈尔滨工业大学; 先进焊接与连接国家重点实验室