2008 年 79 巻 4 号 p. 281-287
Various nondestructive testing have been applied for steel products in manufacturing processes. Ultrasonic inspection is an important method to evaluate inclusions in rolled billets. Conventional ultrasonic transducer with a flat piezoelectric element is used for the inspection. However, ability of inspection for a part of chromium stainless steel billets with coarse grain is insufficient with comparison to the ability for carbon steel billet. This paper describes a result of development of new ultrasonic transducers for the billets with coarse grain. Numerical analysis with finite element method was carried out to make sure a best frequency and wave shape. Two transducers are designed and confirmed advantages over the conventional transducers.