Laser-EMAT ultrasonic resonance detection and high-resolution imaging of thinning damage in high-temperature thin-walled alloys

Abstract

Aero-engine hot-section components are prone to damage forms such as corrosion thinning, creep, and fatigue under complex stress fields and high-speed airflow erosion environments. There is an urgent need to develop a monitoring method suitable for high temperatures and vibrations in extreme operating conditions to enable online inspection of damage in high-temperature alloy components. Therefore, this study proposes a Laser-EMAT ultrasonic shear wave resonance method with large lift-off and high-temperature detection capabilities. It achieves rapid online detection of thinning defects in 800 °C high-temperature thin-walled alloy materials at a lift-off of 5 mm, with a maximum detection error not exceeding 6.07 %. Furthermore, through ultrasonic amplitude-frequency domain multi-feature fusion rapid imaging, high-resolution detection of thin-walled alloys with spherical corrosion thinning defects featuring varying cross-sections and curvature was achieved. The proposed method overcomes key challenges of traditional electromagnetic acoustic resonance (EMAR) detection, such as small lift-off, low energy conversion efficiency, limited high-temperature capability, and the low signal-to-noise ratio of laser ultrasonic detection, particularly its sensitivity to environmental stability. It is expected to be applied in high-temperature online monitoring under complex service conditions.