Reliability of ultrasonic testing

摘要

Since the origins of formal nondestructive testing, radiography has been the preferred testing technique for most industries. This is despite the fact that for some defect types, ultrasonics has always had advantages, for example planar angled defects. The major reason behind this preference was that the radiograph gave a 'hard copy' image that everyone could see and evaluate. Ultrasonics was carried out by a lone individual, who was expected to concentrate for hours at a time, often in difficult, uncomfortable situations, peering at a small screen in case he detected a defect. In this unlucky event, he was expected to make a judgement of what he had seen and if he considered the item under test rejectable, he would probably come under pressure from his customers who would politely question his judgement.