founder
Ultrasonic Examination
DATE
It is the latest NDT method to come to industrial use. The methods of ultrasound had already been discovered by James Precott Joule in 1847 and Pierre Curie in 1880. The first application was proposed after the Titanic sank in 1912. British Richardson detected the presence of icebergs in his patent application by means of ultrasound. During the first world war in France, Chilowski and Langevin worked to detect submarines with ultrasound underwater.
In 1929, Russian Sergei Sokolov proposed using ultrasound to test castings. In the same year, he created high-frequency vibrations in materials using a quartz crystal. During the 2nd world war, the detection of laminations in sheets and inclusions in hot rolled profiles became mandatory. Already existing NDT methods (X-Ray, MT, PT and ET) could not solve these problems.
Industrial use of ultrasonic inspection started simultaneously in 3 countries: USA, UK and Germany. The key guys were Floyd Firestone, Donald O. Sproule, and Adolf Trost, and they didn't know the slightest bit about each other as they were working completely undercover. The patent applications were not even published. Sproule and Trost used the crossover technique with separate transmitter-receiver probes. Trost invented the method called “Trost-Tonge”. The 2 probes meet at the lower and upper corners of the plate, are held in the same axis by a mechanical tool, and are fed by running water on both sides. Sproule placed the 2 probes on the same side of the part. So he invented the bi-crystalline probes. He also used these probes at different distances from each other. He was the first to notice the Firestone echo technique.
WHAT?
Ultrasonic inspection is based on the principle of sending high-frequency sound waves into the material and reflecting them back. Sound waves are sent and received into the material with a single probe with a transceiver feature or by using a transmitting probe and a receiving probe. Since the dimensional dimensions of the part to be tested are known, the sent and received sound attenuation is calculated beforehand for the faultless part, but if there is any error (discontinuity) in the part, the sound attenuation becomes greater and the location of the error appears as an error echo on the screen of the device.