Improvement in Ultrasonic Inspectability by Development of Microstructural Controlled Low Noise Billet and High Sensitivity Probe for Ti-6Al-4V Alloy

As for Ti-6Al-4V alloy billets, the influence of microstructure on ultrasonic noise generation is clarified and the microstructural control technology is developed. Low noise billets can be developed by acceleration of segmentalization and equiaxialization of primary alpha phase that forms colony. Moreover, the phased array probe that achieves better focus attention at the center of billets is developed. Ultrasonic inspection sensitivity by the application of the developed probe to the microstructural controlled 200 mm diameter billet significantly exceeds AMS 2631 Class AA in signal-to-noise ratio.