Application of multizone ultrasonic inspection for great thickness EBW

In the purpose of inspecting great thickness EBW, multizone focused inspection technique was applied. The results of sensitivity testing on the defect specimen were showed: the sensitivity was achieved φ0.4 mm flat bottom holes and signal to noise ratio (S/N) was achieved above 9 dB beyond 70 mm, it achieves the demands of ultrasonic inspection; The signal to noise ratio (S/N) is poor with immersion flat transducer inspection and contact method using longitudinal wave, not achieving the demands of ultrasonic inspection. φ0.4-15dB small defect was discovered with multizone ultrasonic inspection technique beyond 60 mm. and the sensitivity was better than X-ray. So multizone focused inspection was effective for quality evaluation of great thickness EBW.