The ASCO Industries (Hagondange, France) ultrasonic testing equipment gives us the possibility to control the steel in the tank with several high frequencies: 10, 20, 40, and 80 MHz. Depending on the objectives of the control, we are able to adapt the conditions to optimize the results. These controls provide quality indexes to sort our castings and to supply our customers according to their specifications. Because of the presence of debondings around the sulfides, these reflectors have the same C-scan representation as the oxide. However, these two kinds of inclusions have a different influence on the fatigue properties, especially in the case of bearing applications. A method based on signal processing was developed to discriminate the two different reflectors from results obtained with an ultrasound control in tank with an 80-MHz sensor.
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